Exfoliated graphite/titanium dioxide nanocomposites for photodegradation of eosin yellow

NASA Astrophysics Data System (ADS)

Ndlovu, Thabile; Kuvarega, Alex T.; Arotiba, Omotayo A.; Sampath, Srinivasan; Krause, Rui W.; Mamba, Bhekie B.

2014-05-01

An improved photocatalyst consisting of a nanocomposite of exfoliated graphite and titanium dioxide (EG-TiO2) was prepared. SEM and TEM micrographs showed that the spherical TiO2 nanoparticles were evenly distributed on the surface of the EG sheets. A four times photocatalytic enhancement was observed for this floating nanocomposite compared to TiO2 and EG alone for the degradation of eosin yellow. For all the materials, the reactions followed first order kinetics where for EG-TiO2, the rate constant was much higher than for EG and TiO2 under visible light irradiation. The enhanced photocatalytic activity of EG-TiO2 was ascribed to the capability of graphitic layers to accept and transport electrons from the excited TiO2, promoting charge separation. This indicates that carbon, a cheap and abundant material, can be a good candidate as an electron attracting reservoir for photocatalytic organic pollutant degradation.

Structural analysis and corrosion studies on an ISO 5832-9 biomedical alloy with TiO2 sol-gel layers.

PubMed

Burnat, B; Dercz, G; Blaszczyk, T

2014-03-01

The aim of this study was to demonstrate the relationship between the structural and corrosion properties of an ISO 5832-9 biomedical alloy modified with titanium dioxide (TiO2) layers. These layers were obtained via the sol-gel method by acid-catalyzed hydrolysis of titanium isopropoxide in isopropanol solution. To obtain TiO2 layers with different structural properties, the coated samples were annealed at temperatures of 200, 300, 400, 450, 500, 600 and 800 °C for 2 h. For all the prepared samples, accelerated corrosion measurements were performed in Tyrode's physiological solution using electrochemical methods. The most important corrosion parameters were determined: corrosion potential, polarization resistance, corrosion rate, breakdown and repassivation potentials. Corrosion damage was analyzed using scanning electron microscopy. Structural analysis was carried out for selected TiO2 coatings annealed at 200, 400, 600 and 800 °C. In addition, the morphology, chemical composition, crystallinity, thickness and density of the deposited TiO2 layers were determined using suitable electron and X-ray measurement methods. It was shown that the structure and character of interactions between substrate and deposited TiO2 layers depended on annealing temperature. All the obtained TiO2 coatings exhibit anticorrosion properties, but these properties are related to the crystalline structure and character of substrate-layer interaction. From the point of view of corrosion, the best TiO2 sol-gel coatings for stainless steel intended for biomedical applications seem to be those obtained at 400 °C.

Gas sensing properties of very thin TiO2 films prepared by atomic layer deposition (ALD)

NASA Astrophysics Data System (ADS)

Boyadjiev, S.; Georgieva, V.; Vergov, L.; Baji, Zs; Gáber, F.; Szilágyi, I. M.

2014-11-01

Very thin titanium dioxide (TiO2) films of less than 10 nm were deposited by atomic layer deposition (ALD) in order to study their gas sensing properties. Applying the quartz crystal microbalance (QCM) method, prototype structures with the TiO2 ALD deposited thin films were tested for sensitivity to NO2. Although being very thin, the films were sensitive at room temperature and could register low concentrations as 50-100 ppm. The sorption is fully reversible and the films seem to be capable to detect for long term. These initial results for very thin ALD deposited TiO2 films give a promising approach for producing gas sensors working at room temperature on a fast, simple and cost-effective technology.

Effect of TiO2 modification with amino-based self-assembled monolayer on inverted organic solar cell

NASA Astrophysics Data System (ADS)

Tozlu, Cem; Mutlu, Adem; Can, Mustafa; Havare, Ali Kemal; Demic, Serafettin; Icli, Sıddık

2017-11-01

The effects of surface modification of titanium dioxide (TiO2) on the performance of inverted type organic solar cells (i-OSCs) was investigated in this study. A series of benzoic acid derivatized self-assembled monolayer (SAM) molecules of 4‧-[(hexyloxy)phenyl]amino-3,5-biphenyl dicarboxylic acid (CT17) and 4‧-[1-naphthyl (phenyl)amino]biphenyl-4-carboxylic acid (CT19) were utilized to modify the interface between TiO2 buffer layer and poly-3 hexylthiophene (P3HT):[6,6]-phenyl C61 butyric acid methyl ester (PC61BM) active layer having the device structure of ITO/TiO2/SAM/P3HT:PC61BM/MoO3/Ag. The work function and surface wetting properties of TiO2 buffer layer served as electron transporting layer between ITO and PC61BM active layer were tuned by SAM method. The solar cell of the SAM modified devices exhibited better performance. The power conversion efficiency (PCE) of i-OSCs devices with bare TiO2 electrodes enhanced from 2.00% to 2.21% and 2.43% with CT17 and CT19 treated TiO2 electrodes, respectively. The open circuit voltage (Voc) of the SAM treated TiO2 devices reached to 0.60 V and 0.61 V, respectively, while the Voc of untreated TiO2 was 0.57 V. The water contact angle of i-OSCs with CT17 and CT19 SAMs was also higher than the value of the unmodified TiO2 electrode. These results show that inserting a monolayer at the interface between organic and inorganic layers is an useful alternative method to improve the performance of i-OSCs.

Photocatalytic thin films containing TiO2:N nanopowders obtained by the layer-by-layer self-assembling method

NASA Astrophysics Data System (ADS)

Rojas-Blanco, L.; Urzúa, M. D.; Ramírez-Bon, R.; Espinoza Beltrán, F. J.

2012-01-01

In this work, TiO2-N powders were synthesized by high-energy ball milling, using commercial titanium dioxide (TiO2) in the anatase phase and urea to introduce nitrogen into TiO2 in order to enhance their photocatalytic properties in the visible spectral region. Several samples were prepared by milling a mixture of TiO2-urea during 2, 4, 8, 12 and 24 h and characterized by spectroscopic and analytical techniques. X-ray diffraction (XRD) results showed the coexistence of anatase and high-pressure srilankite TiO2 crystalline phases in the samples. Scanning electron microscopy (SEM) revealed that the grain size of the powder samples decreases to 200 nm at 24 h milling time. UV-Vis diffuse reflectance spectroscopic data showed a clear red-shift in the onset of light absorption from 387 to 469 nm as consequence of nitrogen doping in the samples. The photocatalytic activity of the TiO2-N samples was evaluated by methylene blue degradation under visible light irradiation. It was found that TiO2-N samples had higher photocatalytic activity than undoped TiO2 samples, which could be assigned to the effect of introducing N atoms and XPS results confirm it. Using polyethylenimine (PEI), transparent thin films of TiO2-N nanoparticles were prepared by layer-by-layer self assembly method. UV-visible spectrophotometry was employed in a quantitative manner to monitor the adsorbed mass of TiO2 and PEI after each dip cycle. The adsorption of both TiO2 and PEI showed a saturation dip time of 15 min.

Bactericidal effects of silver plus titanium dioxide-coated endotracheal tubes on Pseudomonas aeruginosa and Staphylococcus aureus

PubMed Central

Tarquinio, Keiko M; Kothurkar, Nikhil K; Goswami, Dharendra Y; Sanders, Ronald C; Zaritsky, Arno L; LeVine, Ann Marie

2010-01-01

Purpose: Ventilator-associated pneumonia (VAP) is a nosocomial infection resulting in significant morbidity and mortality. Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) are pathogens associated with VAP. Silver (Ag) coating of endotracheal tubes (ETTs) reduces bacterial colonization, however titanium dioxide (TiO2) coating has not been studied. Methods: Five types of ETT coatings were applied over silica layer: Ag, solgel TiO2, solgel TiO2 with Ag, Degussa P25 TiO2 (Degussa TiO2), and Degussa TiO2 with Ag. After ETTs were incubated with P. aeruginosa or S. aureus; colonization was determined quantitatively. Results: Pseudomonas aeruginosa and S. aureus grew for 5 days on standard ETTs. Compared to standard ETTs, P. aeruginosa growth was significantly inhibited by solgel TiO2 with Ag at 24 hours, and by Degussa TiO2 with Ag at 24 and 48 hours after inoculation. No significant difference in S. aureus growth was observed between the control and any of the five coatings for 5 days. Conclusion: In vitro, solgel TiO2 with Ag and Degussa TiO2 with Ag both attenuated P. aeruginosa growth, but demonstrated no effect on S. aureus colonization. Further studies using alternative coating and incorporating UV light exposure are needed to identify their potential utility in reducing VAP. PMID:20463933

Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

NASA Astrophysics Data System (ADS)

Xiang, Lian; Park, Sang-Shik

2016-12-01

Al2O3-TiO2 (Al-Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol-gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al-Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

Electrical and structural characterization of plasma polymerized polyaniline/TiO2 heterostructure diode: a comparative study of single and bilayer TiO2 thin film electrode.

PubMed

Ameen, Sadia; Akhtar, M Shaheer; Kimi, Young Soon; Yang, O-Bong; Shin, Hyung-Shik

2011-04-01

A heterostructure was fabricated using p-type plasma polymerized polyaniline (PANI) and n-type (single and bilayer) titanium dioxide (TiO2) thin film on FTO glass. The deposition of single and bilayer TiO2 thin film on FTO substrate was achieved through doctor blade followed by dip coating technique before subjected to plasma enhanced polymerization. To fabricate p-n heterostructure, a plasma polymerization of aniline was conducted using RF plasma at 13.5 MHz and at the power of 120 W on the single and bilayer TiO2 thin film electrodes. The morphological, optical and the structural characterizations revealed the formation of p-n heterostructures between PANI and TiO2 thin film. The PANI/bilayer TiO2 heterostructure showed the improved current-voltage (I-V) characteristics due to the substantial deposition of PANI molecules into the bilayer TiO2 thin film which provided good conducting pathway and reduced the degree of excitons recombination. The change of linear I-V behavior of PANI/TiO2 heterostructure to non linear behavior with top Pt contact layer confirmed the formation of Schottky contact at the interfaces of Pt layer and PANI/TiO2 thin film layers.

Suppressing the Photocatalytic Activity of TiO2 Nanoparticles by Extremely Thin Al2O3 Films Grown by Gas-Phase Deposition at Ambient Conditions

PubMed Central

Guo, Jing; Valdesueiro, David; Yuan, Shaojun; Liang, Bin; van Ommen, J. Ruud

2018-01-01

This work investigated the suppression of photocatalytic activity of titanium dioxide (TiO2) pigment powders by extremely thin aluminum oxide (Al2O3) films deposited via an atomic-layer-deposition-type process using trimethylaluminum (TMA) and H2O as precursors. The deposition was performed on multiple grams of TiO2 powder at room temperature and atmospheric pressure in a fluidized bed reactor, resulting in the growth of uniform and conformal Al2O3 films with thickness control at sub-nanometer level. The as-deposited Al2O3 films exhibited excellent photocatalytic suppression ability. Accordingly, an Al2O3 layer with a thickness of 1 nm could efficiently suppress the photocatalytic activities of rutile, anatase, and P25 TiO2 nanoparticles without affecting their bulk optical properties. In addition, the influence of high-temperature annealing on the properties of the Al2O3 layers was investigated, revealing the possibility of achieving porous Al2O3 layers. Our approach demonstrated a fast, efficient, and simple route to coating Al2O3 films on TiO2 pigment powders at the multigram scale, and showed great potential for large-scale production development. PMID:29364840

Improvement of water resistance and dimensional stability of wood through titanium dioxide coating

Treesearch

Qingfeng Sun; Haipeng Yu; Yixing Liu; Jian Li; Yun Lu; John F. Hunt

2010-01-01

Moisture absorption and dimensional distortion are the major drawbacks of wood utilization as building material. In this study, poplar wood coated with a thin layer of titanium dioxide (TiO2) was prepared by the cosolvent-controlled hydrothermal method. Subsequently, its moisture absorption and dimensional stability were examined. Scanning...

Antibacterial effect of hydrogen peroxide-titanium dioxide suspensions in the decontamination of rough titanium surfaces.

PubMed

Wiedmer, David; Petersen, Fernanda Cristina; Lönn-Stensrud, Jessica; Tiainen, Hanna

2017-07-01

The chemical decontamination of infected dental implants is essential for the successful treatment of peri-implantitis. The aim of this study was to assess the antibacterial effect of a hydrogen peroxide-titanium dioxide (H 2 O 2 -TiO 2 ) suspension against Staphylococcus epidermidis biofilms. Titanium (Ti) coins were inoculated with a bioluminescent S. epidermidis strain for 8 h and subsequently exposed to H 2 O 2 with and without TiO 2 nanoparticles or chlorhexidine (CHX). Bacterial regrowth, bacterial load and viability after decontamination were analyzed by continuous luminescence monitoring, live/dead staining and scanning electron microscopy. Bacterial regrowth was delayed on surfaces treated with H 2 O 2 -TiO 2 compared to H 2 O 2 . H 2 O 2 -based treatments resulted in a lower bacterial load compared to CHX. Few viable bacteria were found on surfaces treated with H 2 O 2 and H 2 O 2 -TiO 2 , which contrasted with a uniform layer of dead bacteria for surfaces treated with CHX. H 2 O 2 -TiO 2 suspensions could therefore be considered an alternative approach in the decontamination of dental implants.

Influence of interface layer on optical properties of sub-20 nm-thick TiO2 films

NASA Astrophysics Data System (ADS)

Shi, Yue-Jie; Zhang, Rong-Jun; Li, Da-Hai; Zhan, Yi-Qiang; Lu, Hong-Liang; Jiang, An-Quan; Chen, Xin; Liu, Juan; Zheng, Yu-Xiang; Wang, Song-You; Chen, Liang-Yao

2018-02-01

The sub-20 nm ultrathin titanium dioxide (TiO2) films with tunable thickness were deposited on Si substrates by atomic layer deposition (ALD). The structural and optical properties were acquired by transmission electron microscopy, atomic force microscopy and spectroscopic ellipsometry. Afterwards, a constructive and effective method of analyzing interfaces by applying two different optical models consisting of air/TiO2/Ti x Si y O2/Si and air/effective TiO2 layer/Si, respectively, was proposed to investigate the influence of interface layer (IL) on the analysis of optical constants and the determination of band gap of TiO2 ultrathin films. It was found that two factors including optical constants and changing components of the nonstoichiometric IL could contribute to the extent of the influence. Furthermore, the investigated TiO2 ultrathin films of 600 ALD cycles were selected and then annealed at the temperature range of 400-900 °C by rapid thermal annealing. Thicker IL and phase transition cause the variation of optical properties of TiO2 films after annealing and a shorter electron relaxation time reveals the strengthened electron-electron and electron-phonon interactions in the TiO2 ultrathin films at high temperature. The as-obtained results in this paper will play a role in other studies of high dielectric constants materials grown on Si substrates and in the applications of next generation metal-oxide-semiconductor devices.

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption.

PubMed

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol-gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV-visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm(-2) at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm(-2) from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal.

Synthesis, characterization, and performance evaluation of multilayered photoanodes by introducing mesoporous carbon and TiO2 for humic acid adsorption

PubMed Central

Hosseini, Soraya; Jahangirian, Hossein; Webster, Thomas J; Soltani, Salman Masoudi; Aroua, Mohamed Kheireddine

2016-01-01

Nanostructured photoanodes were prepared via a novel combination of titanium dioxide (TiO2) nanoparticles and mesoporous carbon (C). Four different photoanodes were synthesized by sol–gel spin coating onto a glassy substrate of fluorine-doped tin oxide. The photocatalytic activities of TiO2, TiO2/C/TiO2, TiO2/C/C/TiO2, and TiO2/C/TiO2/C/TiO2 photoanodes were evaluated by exposing the synthesized photoanodes to UV–visible light. The photocurrent density observed in these photoanodes confirmed that an additional layer of mesoporous carbon could successfully increase the photocurrent density. The highest photocurrent density of ~1.022 mA cm−2 at 1 V/saturated calomel electrode was achieved with TiO2/C/C/TiO2 under an illumination intensity of 100 mW cm−2 from a solar simulator. The highest value of surface roughness was measured for a TiO2/C/C/TiO2 combination owing to the presence of two continuous layers of mesoporous carbon. The resulting films had a thickness ranging from 1.605 µm to 5.165 µm after the calcination process. The presence of double-layer mesoporous carbon resulted in a 20% increase in the photocurrent density compared with the TiO2/C/TiO2 combination when only a single mesoporous carbon layer was employed. The improved performance of these photoanodes can be attributed to the enhanced porosity and increased void space due to the presence of mesoporous carbon. For the first time, it has been demonstrated here that the photoelectrochemical performance of TiO2 can be improved by integrating several layers of mesoporous carbon. Comparison of the rate of removal of humic acid by the prepared photoanodes showed that the highest performance from TiO2/C/C/TiO2 was due to the highest photocurrent density generated. Therefore, this study showed that optimizing the sequence of mesoporous carbon layers can be a viable and inexpensive method for enhanced humic acid removal. PMID:27574426

Mo/Si multilayers with enhanced TiO II- and RuO II-capping layers

NASA Astrophysics Data System (ADS)

Yulin, Sergiy; Benoit, Nicolas; Feigl, Torsten; Kaiser, Norbert; Fang, Ming; Chandhok, Manish

2008-03-01

The lifetime of Mo/Si multilayer-coated projection optics is one of the outstanding issues on the road of commercialization of extreme-ultraviolet lithography (EUVL). The application of Mo/Si multilayer optics in EUVL requires both sufficient radiation stability and also the highest possible normal-incidence reflectivity. A serious problem of conventional high-reflective Mo/Si multilayers capped by silicon is the considerable degradation of reflective properties due to carbonization and oxidation of the silicon surface layer under exposure by EUV radiation. In this study, we focus on titanium dioxide (TiO II) and ruthenium dioxide (RuO II) as promising capping layer materials for EUVL multilayer coatings. The multilayer designs as well as the deposition parameters of the Mo/Si systems with different capping layers were optimized in terms of maximum peak reflectivity at the wavelength of 13.5 nm and longterm stability under high-intensive irradiation. Optimized TiO II-capped Mo/Si multilayer mirrors with an initial reflectivity of 67.0% presented a reflectivity drop of 0.6% after an irradiation dose of 760 J/mm2. The reflectivity drop was explained by the partial oxidation of the silicon sub-layer. No reflectivity loss after similar irradiation dose was found for RuO II-capped Mo/Si multilayer mirrors having initial peak reflectivity of 66%. In this paper we present data on improved reflectivity of interface-engineered TiO II- and RuO II-capped Mo/Si multilayer mirrors due to the minimization of both interdiffusion processes inside the multilayer stack and absorption loss in the oxide layer. Reflectivities of 68.5% at the wavelength of 13.4 nm were achieved for both TiO II- and RuO II-capped Mo/Si multilayer mirrors.

Development and characterization of multilayer films of polyaniline, titanium dioxide and CTAB for potential antimicrobial applications.

PubMed

Farias, Emanuel Airton O; Dionisio, Natália A; Quelemes, Patrick V; Leal, Sergio Henrique; Matos, José Milton E; Silva Filho, Edson C; Bechtold, Ivan H; Leite, José Roberto S A; Eiras, Carla

2014-02-01

Composites prepared from polyaniline (PANI) and the ceramic technology of titanium dioxide (TiO2) have been proposed, however, the interaction of these materials with greater control of molecular arrangement becomes attractive in order to achieve properties not previously described or yet the optimization of those already reported. Therefore, in this study, thin hybrid films made of polyaniline (PANI), a conductive polymer, and the technological ceramic, titanium dioxide (TiO2), were prepared by the layer-by-layer (LbL) self-assembly technique. The films were characterized by cyclic voltammetry (CV), UV-VIS spectroscopy and atomic force microscopy (AFM). Aiming to improve the dispersion of the ceramic in the polymer matrix, the commercial surfactant, cetyl trimethylammonium bromide (CTAB), was used in the formation of the films. The best condition of deposition was found showing synergic interactions between the conjugated materials. The antibacterial activity of the PANI(TiO2)/CTAB films was studied and the obtained results suggest their use as antimicrobial coatings. Copyright © 2013 Elsevier B.V. All rights reserved.

Structure and optical properties of TiO2 thin films deposited by ALD method

NASA Astrophysics Data System (ADS)

Szindler, Marek; Szindler, Magdalena M.; Boryło, Paulina; Jung, Tymoteusz

2017-12-01

This paper presents the results of study on titanium dioxide thin films prepared by atomic layer deposition method on a silicon substrate. The changes of surface morphology have been observed in topographic images performed with the atomic force microscope (AFM) and scanning electron microscope (SEM). Obtained roughness parameters have been calculated with XEI Park Systems software. Qualitative studies of chemical composition were also performed using the energy dispersive spectrometer (EDS). The structure of titanium dioxide was investigated by X-ray crystallography. A variety of crystalline TiO2 was also confirmed by using the Raman spectrometer. The optical reflection spectra have been measured with UV-Vis spectrophotometry.

Properties of TiO2 thin films and a study of the TiO2-GaAs interface

NASA Technical Reports Server (NTRS)

Chen, C. Y.; Littlejohn, M. A.

1977-01-01

Titanium dioxide (TiO2) films prepared by chemical vapor deposition were investigated in this study for the purpose of the application in the GaAs metal-insulator-semiconductor field-effect transistor. The degree of crystallization increases with the deposition temperature. The current-voltage study, utilizing an Al-TiO2-Al MIM structure, reveals that the d-c conduction through the TiO2 film is dominated by the bulk-limited Poole-Frenkel emission mechanism. The dependence of the resistivity of the TiO2 films on the deposition environment is also shown. The results of the capacitance-voltage study indicate that an inversion layer in an n-type substrate can be achieved in the MIS capacitor if the TiO2 films are deposited at a temperature higher than 275 C. A process of low temperature deposition followed by the pattern definition and a higher temperature annealing is suggested for device fabrications. A model, based on the assumption that the surface state densities are continuously distributed in energy within the forbidden band gap, is proposed to interpret the lack of an inversion layer in the Al-TiO2-GaAs MIS structure with the TiO2 films deposited at 200 C.

Construction of surface HA/TiO2 coating on porous titanium scaffolds and its preliminary biological evaluation.

PubMed

Chen, Hongjie; Wang, Chunli; Yang, Xiao; Xiao, Zhanwen; Zhu, Xiangdong; Zhang, Kai; Fan, Yujiang; Zhang, Xingdong

2017-01-01

A simple approach to fabricating hydroxyxapatite/titanium dioxide (HA/TiO 2 ) coating on porous titanium (Ti) scaffolds was developed in the present study. Surface TiO 2 layer was firstly formed on porous Ti scaffolds with multi-scale pores by acid-alkali (AA) treatment. The outer HA layer was then formed on the TiO 2 layer by subsequent pulse electrochemical deposition (ED) technique. All the three main process parameters, i.e. deposition times, current density and mass transfer mode affected the properties of the HA coating notably. Under the conditions of 90 deposition cycles, -10mA/cm 2 of pulse current density and stirring, a thin layer of homogeneous and nanorod-like HA sediments was formed on the substrate surface of porous Ti scaffolds. The results of protein adsorption and cellular experiments showed that compared to the single TiO 2 surface, the HA/TiO 2 surface allowed more adsorption of serum proteins and further enhanced the alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts. Copyright © 2016 Elsevier B.V. All rights reserved.

Observation the Distribution of Titanium Dioxide Nano-particles in an Experimental Tumor Tissue by a Raman Microscope

NASA Astrophysics Data System (ADS)

Bibin, Andriana B.; Kume, Kyo; Tsutumi, Kotaro; Fukunaga, Yukihiro; Ito, Shinnji; Imamura, Yoshiaki; Miyoshi, Norio

2011-12-01

One of the most important technologies of the 21st century is nanotechnology. Many researchers will have been focusing to employ nanotechnology for medical purpose. Our team was interested in focusing to the application of titanium dioxide (TiO2), as nano-particles, for medical purpose especially drug delivery for the cancer and tumor. The administrations of TiO2 nano-particle via the oral administration of the interface layer particles into the mouse transplanted squamous-cell-carcinoma (SCC) have already conducted. Histology study and Raman spectroscope data were applied to the serial section of frozen tumor tissue in order to observe the distribution of TiO2 nano-particle within the SCC tissue. We used near infrared laser Raman microscopy system, the wavelength is 785 nm. Hematoxyline & eosin stained image and the Raman microscopy system were also used for analyzing the photodynamic therapy (PDT) with 5-ALA and TiO2-particle-sol [TiO2]-ALA-treated tumor samples. As the result, we demonstrated the distribution of TiO2, where TiO2 particles were detected to be distributed in the blood vessel at the bleeding in the SCC tumor tissue. PDT with TiO2 nano-particles that is presented in the SCC-transplanted mouse tumor model can cause the enhancement of photodynamic reaction by nano-particles. Therefore, the combinations of PDT with TiO2 nano-particles may have a possibility to be introduced to the human body in near future for diagnose and PDT treatment of the tumor.

Fabrication of TiO2 nanostructures on porous silicon for thermoelectric application

NASA Astrophysics Data System (ADS)

Fahrizal, F. N.; Ahmad, M. K.; Ramli, N. M.; Ahmad, N.; Fakhriah, R.; Mohamad, F.; Nafarizal, N.; Soon, C. F.; Ameruddin, A. S.; Faridah, A. B.; Shimomura, M.; Murakami, K.

2017-09-01

Nowadays, technology is moving by leaps and bounds over the last several decades. This has created new opportunities and challenge in the research fields. In this study, the experiment is about to investigate the potential of Titanium Dioxide (TiO2) nanostructures that have been growth onto a layer of porous silicon (pSi) for their thermoelectric application. Basically, it is divided into two parts, which is the preparation of the porous silicon (pSi) substrate by electrochemical-etching process and the growth of the Titanium Dioxide (TiO2) nanostructures by hydrothermal method. This sample have been characterize by Field Emission Scanning Electron Microscopy (FESEM) to visualize the morphology of the TiO2 nanostructures area that formed onto the porous silicon (pSi) substrate. Besides, the sample is also used to visualize their cross-section images under the FESEM microscopy. Next, the sample is characterized by the X-Ray Diffraction (XRD) machine. The XRD machine is used to get the information about the chemical composition, crystallographic structure and physical properties of materials.

Biomedical bandpass filter for fluorescence microscopy imaging based on TiO2/SiO2 and TiO2/MgF2 dielectric multilayers

NASA Astrophysics Data System (ADS)

Butt, M. A.; Fomchenkov, S. A.; Ullah, A.; Verma, P.; Khonina, S. N.

2016-08-01

We report a design for creating a multilayer dielectric optical filters based on TiO2 and SiO2/MgF2 alternating layers. We have selected Titanium dioxide (TiO2) for high refractive index (2.5), Silicon dioxide (SiO2) and Magnesium fluoride (MgF2) as a low refractive index layer (1.45 & 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Reflectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer range. Therefore a bandpass filters are required to restrict wavelength outside the stopband of the FP DBRs. The proposed filter shows a high quality with average transmission of 97.4% within the passbands and the transmission outside the passband is around 4%. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptional choice for florescence imaging and Endoscope narrow band imaging.

Effect of titanium oxide compact layer in dye-sensitized solar cell prepared by liquid-phase deposition

NASA Astrophysics Data System (ADS)

Huang, Jung-Jie; Chiu, Shih-Ping; Wu, Menq-Jion; Hsu, Chun-Fa

2016-11-01

In this study, titanium dioxide films were deposited on indium tin oxide glass substrates by liquid-phase deposition (LPD) for application as the compact layer in dye-sensitized solar cells (DSSCs). A deposition solution of ammonium hexafluorotitanate and boric acid was used for TiO2 deposition. Compact layer passivation can improve DSSC performance by decreasing carrier losses from recombination at the ITO/electrolyte interface and improving the electrical contact between the ITO and the TiO2 photo-electrode. The optimum thickness of the compact layer was found to be 48 nm, which resulted in a 50 % increase in the conversion efficiency compared with cells without compact layers. The conversion efficiency can be increased from 3.55 to 5.26 %. Therefore, the LPD-TiO2 compact layer inhibits the dark current and increases the short-circuit current density effectively.

A study of the physical, chemical and biological properties of TiO2 coatings produced by micro-arc oxidation in a Ca-P-based electrolyte.

PubMed

dos Santos, Amanda; Araujo, Joyce R; Landi, Sandra M; Kuznetsov, Alexei; Granjeiro, José M; de Sena, Lidia Ágata; Achete, Carlos Alberto

2014-07-01

In this work, a porous and homogeneous titanium dioxide layer was grown on commercially pure titanium substrate using a micro-arc oxidation (MAO) process and Ca-P-based electrolyte. The structure and morphology of the TiO2 coatings were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, and profilometry. The chemical properties were studied using electron dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy. The wettability of the coating was evaluated using contact angle measurements. During the MAO process, Ca and P ions were incorporated into the oxide layer. The TiO2 coating was composed of a mixture of crystalline and amorphous structures. The crystalline part of the sample consisted of a major anatase phase and a minor rutile phase. A cross-sectional image of the coating-substrate interface reveals the presence of voids elongated along the interface. An osteoblast culture was performed to verify the cytocompatibility of the anodized surface. The results of the cytotoxicity tests show satisfactory cell viability of the titanium dioxide films produced in this study.

Integration of micro nano and bio technologies with layer-by-layer self-assembly

NASA Astrophysics Data System (ADS)

Kommireddy, Dinesh Shankar

In the past decade, layer-by-layer (LbL) nanoassembly has been used as a tool for immobilization and surface modification of materials with applications in biology and physical sciences. Often, in such applications, LbL assembly is integrated with various techniques to form functional surface coatings and immobilized matrices. In this work, integration of LbL with microfabrication and microfluidics, and tissue engineering are explored. In an effort to integrate microfabrication with LbL nanoassembly, microchannels were fabricated using soft-lithography and the surface of these channels was used for the immobilization of materials using LbL and laminar flow patterning. Synthesis of poly(dimethyldiallyl ammonium chloride)/poly(styrene sulfonate) and poly(dimethyldiallyl ammonium chloride)/bovine serum albumin microstrips is demonstrated with the laminar flow microfluidic reactor. Resulting micropatterns are 8-10 mum wide, separated with few micron gaps. The width of these microstrips as well as their position in the microchannel is controlled by varying the flow rate, time of interaction and concentration of the individual components, which is verified by numerical simulation. Spatially resolved pH sensitivity was observed by modifying the surface of the channel with a pH sensitive dye. In order to investigate the integration of LbL assembly with tissue engineering, glass substrates were coated with nanoparticle/polyelectrolyte layers, and two different cell types were used to test the applicability of these coatings for the surface modification of medical implants. Titanium dioxide (TiO 2), silicon dioxide, halloysite and montmorillonite nanoparticles were assembled with oppositely charged polyelectrolytes. In-vitro cytotoxicity tests of the nanoparticle substrates on human dermal firbroblasts (HDFs) showed that the nanoparticle surfaces do not have toxic effects on the cells. HDFs retained their phenotype on the nanoparticle coatings, by synthesizing type-I collagen. These cells also showed active proliferation on the nanoparticle substrates. Cells attached on TiO2 substrates showed faster rate of spreading compared with the other types of nanoparticle coatings. Mesenchymal stem cells (MSCs) were used as a second cell type to support and elaborate on the results obtained with the HDFs. Increasing surface roughness was observed with increasing number of layers of TiO2. Tests with a higher number of layers of TiO2, showed an increased attachment, proliferation and faster spreading of the MSCs on a larger number of layers of TiO2.

Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium

NASA Astrophysics Data System (ADS)

Jain, N.; Zhu, Y.; Maurya, D.; Varghese, R.; Priya, S.; Hudait, M. K.

2014-01-01

We have investigated the structural and band alignment properties of nanoscale titanium dioxide (TiO2) thin films deposited on epitaxial crystallographic oriented Ge layers grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy. The TiO2 thin films deposited at low temperature by physical vapor deposition were found to be amorphous in nature, and high-resolution transmission electron microscopy confirmed a sharp heterointerface between the TiO2 thin film and the epitaxially grown Ge with no traceable interfacial layer. A comprehensive assessment on the effect of substrate orientation on the band alignment at the TiO2/Ge heterointerface is presented by utilizing x-ray photoelectron spectroscopy and spectroscopic ellipsometry. A band-gap of 3.33 ± 0.02 eV was determined for the amorphous TiO2 thin film from the Tauc plot. Irrespective of the crystallographic orientation of the epitaxial Ge layer, a sufficient valence band-offset of greater than 2 eV was obtained at the TiO2/Ge heterointerface while the corresponding conduction band-offsets for the aforementioned TiO2/Ge system were found to be smaller than 1 eV. A comparative assessment on the effect of Ge substrate orientation revealed a valence band-offset relation of ΔEV(100) > ΔEV(111) > ΔEV(110) and a conduction band-offset relation of ΔEC(110) > ΔEC(111) > ΔEC(100). These band-offset parameters are of critical importance and will provide key insight for the design and performance analysis of TiO2 for potential high-κ dielectric integration and for future metal-insulator-semiconductor contact applications with next generation of Ge based metal-oxide field-effect transistors.

The structure of biocoats based on TiO2 doped with nitrogen study

NASA Astrophysics Data System (ADS)

Boytsova, E. L.; Leonova, L. A.; Pichugin, V. F.

2018-04-01

Nitrogen-doped titanium dioxide (N-TiO2) nanofilms were deposited by reactive magnetron sputtering under different bias voltage. The mode of sputtering influences to formation and properties of titanium films. X-ray diffraction (XRD) was used to study the phase transition and crystallinity of the nanofilms. A technique of layer-by-layer measurement of Raman scattering from nanostructured titanium dioxide films based on a preliminary sputtering of the films by argon beam under an angle of 45° and less has been developed. Experimentally confirmed low dissolution rate of the coating in NaCl saline (0.9%).

Characteristics of dye Rhoeo spathacea in dye sensitizer solar cell (DSSC)

NASA Astrophysics Data System (ADS)

Sumardiasih, Sri; Obina, Wilfrida M.; Cari; Supriyanto, Agus; Septiawan, Trio Y.; Khairuddin

2017-01-01

Dye-sensitized solar cell (DSSC) is a device that converts solar energy into electrical energy. The magnitude of the efficiency of DSSC is mainly based on the amount of dye absorbed by the surface of TiO2. In this work, used natural dye extracted from leaves Rhoeo spathacea. The dye partially used to immerse of TiO2 as working electrodes, and the rest are directly mixed TiO2 paste to obtain dye titanium dioxide.The paste TiO2 and dye titanium dioxide coated onto the fluorine-doped tin oxide (FTO) glass plate by spin coating method. The absorbance spectra of the dye, dye titanium dioxide and TiO2 were obtained by UV-Vis spectroscopy. The conductivity of the dye, dye titanium dioxide, and TiO2 was measured by two point probe El-Kahfi 100. The DSSC based on dye titanium dioxide that stirring for 5 hours the highest efficiency of 0,0520 % whereas those based on TiO2 immersed for 36 hours showed achieved 0,0501 % obtained from I-V characterization.

Low temperature growth of ZnO nanorods array via solution-immersion on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

In this work, TiO2:ZNR thin films were successfully fabricated on glass substrates at low temperatures of 75 to 90°C. The substrates were coated with titanium dioxide (TiO2) using sol-gel spin coating, which act as seed layer to grow zinc oxide nanorods (ZNR) by solution-immersion method. At 90 and 95° C, ZNR with hexagonal tip are well dispersed without any aggregation and exhibit more uniform nanorods array as observed using FESEM. The diffraction peak intensity of the (0 0 2)-plane increased as the temperature increased, indicating improved orientation in the c-axis direction of the ZNR as detected in XRD patterns. From UV-Vis absorbance spectra, it was found that the samples has higher absorption properties at middle range of immersion temperatures; 80, 85 and 90°C.

Distributed feedback laser biosensor incorporating a titanium dioxide nanorod surface

NASA Astrophysics Data System (ADS)

Ge, Chun; Lu, Meng; Zhang, Wei; Cunningham, Brian T.

2010-04-01

A dielectric nanorod structure is used to enhance the label-free detection sensitivity of a vertically-emitting distributed feedback laser biosensor (DFBLB). The device is comprised of a replica molded plastic grating that is subsequently coated with a dye-doped polymer layer and a TiO2 nanorod layer produced by the glancing angle deposition technique. The DFBLB emission wavelength is modulated by the adsorption of biomolecules, whose greater dielectric permittivity with respect to the surrounding liquid media will increase the laser wavelength in proportion to the density of surface-adsorbed biomaterial. The nanorod layer provides greater surface area than a solid dielectric thin film, resulting in the ability to incorporate a greater number of molecules. The detection of a monolayer of protein polymer poly (Lys, Phe) is used to demonstrate that a 90 nm TiO2 nanorod structure improves the detection sensitivity by a factor of 6.6 compared to an identical sensor with a nonporous TiO2 surface.

TiO2 as diffusion barrier at Co/Alq3 interface studied by x-ray standing wave technique

NASA Astrophysics Data System (ADS)

Phatak Londhe, Vaishali; Gupta, A.; Ponpandian, N.; Kumar, D.; Reddy, V. R.

2018-06-01

Nano-scale diffusion at the interfaces in organic spin valve thin films plays a vital role in controlling the performance of magneto-electronic devices. In the present work, it is shown that a thin layer of titanium dioxide at the interface of Co/Alq3 can act as a good diffusion barrier. The buried interfaces of Co/Alq3/Co organic spin valve thin film has been studied using x-ray standing waves technique. A planar waveguide is formed with Alq3 layer forming the cavity and Co layers as the walls of the waveguide. Precise information about diffusion of Co into Alq3 is obtained through excitation of the waveguide modes. It is found that the top Co layer diffuses deep into the Alq3 resulting in incorporation of 3.1% Co in the Alq3 layer. Insertion of a 1.7 nm thick barrier layer of TiO2 at Co/Alq3 interface results in a drastic reduction in the diffusion of Co into Alq3 to a value of only 0.4%. This suggests a better performance of organic spin valve with diffusion barrier of TiO2.

Synthesis and characterization of UV-treated Fe-doped bismuth lanthanum titanate-doped TiO2 layers in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Song, Myoung Geun; Bark, Chung Wung

2016-06-01

Dye-sensitized solar cells (DSSCs) based on titanium dioxide (TiO2) have been extensively studied because they constitute promising low-cost alternatives to their conventional semiconductor-based counterparts. However, much of the effort aimed at achieving high conversion efficiencies has focused on dye and liquid electrolytes. In this work, we report the photovoltaic characteristics of DSSCs fabricated by mixing TiO2 with Fe-doped bismuth lanthanum titanate (Fe-BLT). These nanosized Fe-BLT powders were prepared by using a high-energy ball-milling process. In addition, we used a UV radiation-ozone (UV-O3) treatment to change the surface wettability of TiO2 from hydrophobic to hydrophilic and thereby prevented the easy separation of the Fe-BLT-mixed TiO2 from the fluorine-doped tin-oxide (FTO) coating glass.

Influence of TiCl4 post-treatment condition on TiO2 electrode for enhancement photovoltaic efficiency of dye-sensitized solar cells.

PubMed

Eom, Tae Sung; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

2014-10-01

Titanium tetrachloride (TiCl4) treatment processed by chemical bath deposition is usually adopted as pre- and post-treatment for nanocrystalline titanium dioxide (TiO2) film deposition in the dye-sensitized solar cells (DSSCs) technology. TiCl4 post-treatment is a widely known method capable of improving the performance of dye-sensitized solar cells. In this work, the effect of TiCl4 post-treatment on the TiO2 electrode is proposed and compared to the untreated film. A TiO2 passivating layer was deposited on FTO glass by RF magnetron sputtering. The TiO2 sol prepared sol-gel method, nanoporous TiO2 upper layer was deposited by screen printing method on the passivating layer. TiCl4 post-treatment was deposited on the substrate by hydrolysis of TiCl4 aqueous solution. Crystalline structure was adjusted by various TiCl4 concentration and dipping time: 20 mM-150 mM and 30 min-120 min. The conversion efficiency was measured by solar simulator (100 mW/cm2). The dye-sensitized solar cell using TiCl4 post-treatment was measured the maximum conversion efficiency of 5.04% due to electron transport effectively. As a result, the DSSCs based on TiCl4 post-treatment showed better photovoltaic performance than cells made purely of TiO2 nanoparticles. The relative DSSCs devices are characterized in terms of short circuit current density, open circuit voltage, fill factor, conversion efficiency.

Inhibition of Crystal Growth during Plasma Enhanced Atomic Layer Deposition by Applying BIAS

PubMed Central

Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

2015-01-01

In this study, the influence of direct current (DC) biasing on the growth of titanium dioxide (TiO2) layers and their nucleation behavior has been investigated. Titania films were prepared by plasma enhanced atomic layer deposition (PEALD) using Ti(OiPr)4 as metal organic precursor. Oxygen plasma, provided by remote inductively coupled plasma, was used as an oxygen source. The TiO2 films were deposited with and without DC biasing. A strong dependence of the applied voltage on the formation of crystallites in the TiO2 layer is shown. These crystallites form spherical hillocks on the surface which causes high surface roughness. By applying a higher voltage than the plasma potential no hillock appears on the surface. Based on these results, it seems likely, that ions are responsible for the nucleation and hillock growth. Hence, the hillock formation can be controlled by controlling the ion energy and ion flux. The growth per cycle remains unchanged, whereas the refractive index slightly decreases in the absence of energetic oxygen ions. PMID:28793679

Influence of coating steps of perovskite on low-temperature amorphous compact TiO x upon the morphology, crystallinity, and photovoltaic property correlation in planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Shahiduzzaman, Md.; Furumoto, Yoshikazu; Yamamoto, Kohei; Yonezawa, Kyosuke; Azuma, Yosuke; Kitamura, Michinori; Matsuzaki, Hiroyuki; Karakawa, Makoto; Kuwabara, Takayuki; Takahashi, Kohshin; Taima, Tetsuya

2018-03-01

The fabrication of high-efficiency solution-processable perovskite solar cells has been achieved using mesostructured films and compact titanium dioxide (TiO2) layers in a process that involves high temperatures and cost. Here, we present an efficient approach for fabricating chemical-bath-deposited, low-temperature, and low-cost amorphous compact TiO x -based planar heterojunction perovskite solar cells by one-step and two-step coatings of the perovskite layer. We also investigate the effect of the number of perovskite coating steps on the compact TiO x layer. The grazing incidence wide-angle X-ray scattering technique is used to clarify the relationship between morphology, crystallinity, and photovoltaic properties of the resulting devices. Analysis of the films revealed that one-step spin-coating of perovskite exhibited an enhancement of film quality and crystallization that correlates to photovoltaic performance 1.5 times higher than that of a two-step-coated device. Our findings show that the resulting morphology, crystallinity, and device performances are strongly dependent on the number of coating steps of the perovskite thin layer on the compact TiO x layer. This result is useful knowledge for the low-cost production of planar perovskite solar cells.

Effect of Atomic Layer Depositions (ALD)-Deposited Titanium Oxide (TiO2) Thickness on the Performance of Zr40Cu35Al15Ni10 (ZCAN)/TiO2/Indium (In)-Based Resistive Random Access Memory (RRAM) Structures

DTIC Science & Technology

2015-08-01

metal structures, memristors, resistive random access memory, RRAM, titanium dioxide, Zr40Cu35Al15Ni10, ZCAN, resistive memory, tunnel junction 16...TiO2 thickness ........................6 1 1. Introduction Resistive-switching memory elements based on metal-insulator-metal (MIM) diodes ...have attracted great interest due to their potential as components for simple, inexpensive, and high-density non-volatile storage devices. MIM diodes

Anatase/rutile bi-phasic titanium dioxide nanoparticles for photocatalytic applications enhanced by nitrogen doping and platinum nano-islands.

PubMed

Bear, Joseph C; Gomez, Virginia; Kefallinos, Nikolaos S; McGettrick, James D; Barron, Andrew R; Dunnill, Charles W

2015-12-15

Titanium dioxide (TiO2) bi-phasic powders with individual particles containing an anatase and rutile hetero-junction have been prepared using a sequential layer sol-gel deposition technique to soluble substrates. Sequential thin films of rutile and subsequently anatase TiO2 were deposited onto sodium chloride substrates yielding extremely fragile composite layered discs that fractured into "Janus-like" like powders on substrate dissolution. Nitrogen doped and platinum sputtered analogues were also prepared, and analysed for photocatalytic potential using the photodegradation of Rhodamine B, a model organic pollutant under UV and visible light irradiation. The materials were characterised using X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and scanning electron microscopy. This paper sheds light on the relationship between anatase and rutile materials when in direct contact and demonstrates a robust method for the synthesis of bi-phasic nanoparticles, ostensibly of any two materials, for photocatalytic reactions or otherwise. Copyright © 2015 Elsevier Inc. All rights reserved.

Synthesis of polycarbonate-r-polyethylene glycol copolymer for templated synthesis of mesoporous TiO2 films.

PubMed

Patel, Rajkumar; Kim, Jinkyu; Lee, Chang Soo; Kim, Jong Hak

2014-12-01

We synthesized a novel polycarbonate Z-r-polyethylene glycol (PCZ-r-PEG) copolymer by solution polycondensation. Successful synthesis of PCZ-r-PEG copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), and transmission electron microscopy (TEM). PCZ-r-PEG copolymer was used as a structure-directing agent for fabrication of mesoporous thin film containing a titanium dioxide (TiO2) layer. To control the porosity of the resultant inorganic layer, the ratio of titanium(IV) isopropoxide (TTIP) to PCZ-r-PEG copolymer was varied. The structure and porosity of the resulting mesoporous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. Mesoporous TiO2 films fabricated on an F-doped tin oxide (FTO) surface were used as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs). The highest efficiency achieved was 3.3% at 100 mW/cm2 for a film thickness of 750 nm, which is high considering the thickness of TiO2 film, indicating the importance of the structure-directing agent.

Investigations into the structure of PEO-layers for understanding of layer formation

NASA Astrophysics Data System (ADS)

Friedemann, A. E. R.; Thiel, K.; Haßlinger, U.; Ritter, M.; Gesing, Th. M.; Plagemann, P.

2018-06-01

Plasma electrolytic oxidation (PEO) is a type of high-voltage anodic oxidation process capable of producing a thick oxide layer with a wide variety of structural and chemical properties influenced by the electrolytic system. This process enables the combined adjustment of various characteristics, i.e. the morphology and chemical composition. The procedure facilitates the possibility of generating an individual structure as well as forming a crystalline surface in a single step. A highly porous surface with a high crystalline content consisting of titanium dioxide phases is ensured through the process of plasma electrolytic oxidizing pure titanium. In the present study plasma electrolytic oxidized TiO2-layers were investigated regarding their crystallinity through the layer thickness. The layers were prepared with a high applied voltage of 280 V to obtain a PEO-layer with highly crystalline anatase and rutile amounts. Raman spectroscopy and electron backscatter diffraction (EBSD) were selected to clarify the structure of the oxide layer with regard to its crystallinity and phase composition. The composition of the TiO2-phases is more or less irregularly distributed as a result of the higher energy input on the uppermost side of the layer. Scanning transmission electron microscopy (STEM) provided a deeper understanding of the structure and the effects of plasma discharges on the layer. It was observed that the plasma discharges have a strong influence on crystallite formation on top of the oxide layer and also at the boundary layer to the titanium substrate. Therefore, small crystallites of TiO2 could be detected in these regions. In addition, it was shown that amorphous TiO2 phases are formed around the characteristic pore structures, which allows the conclusion to be drawn that a rapid cooling from the gas phase had to take place in these areas.

Pulsed Laser Deposited Ferromagnetic Chromium Dioxide thin Films for Applications in Spintronics

NASA Astrophysics Data System (ADS)

Dwivedi, S.; Jadhav, J.; Sharma, H.; Biswas, S.

Stable rutile type tetragonal chromium dioxide (CrO2) thin films have been deposited on lattice-matched layers of TiO2 by KrF excimer laser based pulsed laser deposition (PLD) technique using Cr2O3 target. The TiO2 seed layer was deposited on oxidized Si substrates by the same PLD process followed by annealing at 1100 °C for 4 h. The lattice-matched interfacial layer is required for the stabilization of Cr (IV) phase in CrO2, since CrO2 behaves as a metastable compound under ambient conditions and readily converts into its stable phase of Cr (III) oxide, Cr2O3. Analyses with X-ray diffraction (XRD), Glancing-angle XRD (GIXRD), Raman spectroscopy and grazing-angle Fourier transform infra-red (FTIR) spectroscopy confirm the presence of tetragonal CrO2 phase in the as-deposited films. Microstructure and surface morphology in the films were studied with field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Electrical and magnetic characterizations of the films were performed at room temperature. Such type of stable half-metallic CrO2 thin films with low field magnetoresistive switching behaviour are in demand for applications as diverse as spin-FETs, magnetic sensors, and magneto-optical devices.

Nanoparticle-induced oxidation of corona proteins initiates an oxidative stress response in cells†

PubMed Central

Jayaram, Dhanya T.; Runa, Sabiha; Kemp, Melissa L.

2017-01-01

Titanium dioxide nanoparticles (TiO2 NPs), used as pigments and photocatalysts, are ubiquitous in our daily lives. Previous work has observed cellular oxidative stress in response to the UV-excitation of photocatalytic TiO2 NPs. In comparison, most human exposure to TiO2 NPs takes place in the dark, in the lung following inhalation or in the gut following consumption of TiO2 NP food pigment. Our spectroscopic characterization shows that both photocatalytic and food grade TiO2 NPs, in the dark, generate low levels of reactive oxygen species (ROS), specifically hydroxyl radicals and superoxides. These ROS oxidize serum proteins that form a corona of proteins on the NP surface. This protein layer is the interface between the NP and the cell. An oxidized protein corona triggers an oxidative stress response, detected with PCR and western blotting. Surface modification of TiO2 NPs to increase or decrease surface defects correlates with ROS generation and oxidative stress, suggesting that NP surface defects, likely oxygen vacancies, are the underlying cause of TiO2 NP-induced oxidative stress. PMID:28537609

Titanium dioxide-based carbon monoxide gas sensors: Effects of crystallinity and chemistry on sensitivity

NASA Astrophysics Data System (ADS)

Seeley, Zachary Mark

Among metal-oxide gas sensors which change electrical resistive properties upon exposure to target gasses, titanium dioxide (TiO2) has received attention for its sensitivity and stability during high temperature (>500°C) operation. However, due to the sensing mechanism sensitivity, selectivity, and stability remain as critical deficiencies to be resolved before these sensors reach commercial use. In this study, TiO2 thick films of approximately 30mum and thin films of approximately 1mum thick were fabricated to assess the influence of their material properties on gas sensing mechanism. Increased calcination temperature of TiO2 thick films led to grain growth, reduction in specific surface area, and particle-particle necking. These properties are known to degrade sensitivity; however the measured carbon monoxide (CO) gas response improved with increasing calcination temperature up to 800°C. It was concluded that the sensing improvement was due to increased crystallinity within the films. Sensing properties of TiO2 thin films of were also dependent on crystallization, however; due to the smaller volume of material, they reached optimized crystallization at lower temperatures of 650°C, compared to 800°C for thick films. Incorporation of tungsten (W) and nickel (Ni) ions into the films created donor and acceptor defect sites, respectively, within the electronic band gap of TiO2. The additional n-type defects in W-doped TiO 2 improved n-type CO response, while p-type defects in Ni-doped TiO 2 converted the gas response to p-type. Chemistry of thin films had a more significant impact on the electrical properties and gas response than did microstructure or crystallinity. Doped films could be calcined at higher temperatures and yet remain highly sensitive to CO. Thin films with p-n bi-layer structure were fabricated to determine the influence of a p-n junction on gas sensing properties. No effect of the junction was observed and the sensing response neared the average of the layers; however, electrical and gas response studies revealed that the majority of the conductivity and gas-surface reactions took place on the outer layer of the film. Further research is necessary to understand the influence of p-n junctions on the gas sensing behavior.

Depletion Of The Protective Aluminum Hydroxide Coating In TiO2-Based Sunscreens By Swimming Pool Water Ingredients

EPA Science Inventory

In sunscreen lotion (SSL) formulations, titanium dioxide (nTiO₂) nanoparticles are coated with an Al(OH)₃ layer to shield against the harmful effects of hydroxyl radicals (•OH), superoxide anion radicals (O₂^-•), and other reactive oxyge...

Titanium Dioxide Volatility in High Temperature Water Vapor

NASA Technical Reports Server (NTRS)

Nguyen, QynhGiao N.

2008-01-01

Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study will evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400 C - 1200 C in water containing environments to determine the volatile hydroxyl species using the transpiration method. The water content ranged from 0-76 mole% and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation for all three temperatures: TiO2 (s) + H2O (g) = TiO(OH)2 (g).

Orientation-Controllable ZnO Nanorod Array Using Imprinting Method for Maximum Light Utilization in Dye-Sensitized Solar Cells.

PubMed

Jeong, Huisu; Song, Hui; Lee, Ryeri; Pak, Yusin; Kumaresan, Yogeenth; Lee, Heon; Jung, Gun Young

2015-12-01

We present a holey titanium dioxide (TiO2) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO2 film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO2 film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold. The photoanode composed of the holey TiO2 film with the ZNL synergistically utilized the sunlight due to enhanced light scattering and absorption. The best power conversion efficiency of 8.5 % was achieved from the DSC with the standing ZNL, which represented a 33 % improvement compared to the reference cell with a planar TiO2.

Surface micro-dissolve method of imparting self-cleaning property to cotton fabrics in NaOH/urea aqueous solution

NASA Astrophysics Data System (ADS)

Fan, Tao; Hu, Ruimin; Zhao, Zhenyun; Liu, Yiping; Lu, Ming

2017-04-01

A simple and economical micro-dissolved process of embedding titanium dioxide (TiO2) nanoparticles into surface zone of cotton fabrics was developed. TiO2 was coated on cotton fabrics in 7% wt NaOH/12% wt urea aqueous solution at low temperature. Photocatalytic efficiency of cotton fabrics treated with TiO2 nanoparticles was studied upon measuring the photocatalytic decoloration of Rhodamine B (RhB) under ultraviolet irradiation. Self-cleaning property of cotton fabric coated with TiO2 was evaluated with color depth of samples (K/S value). The treated fabrics were characterized using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectroscopy (FITR), tensile strength, stiffness and whiteness. The results indicated, TiO2 nanoparticles could be embedded on the surface layer of cotton fabrics throuth surface micro-dissolve method. Treated cotton fabrics possessed distinct photocatalytic efficiency and self-cleaning properties. Tensile strength and whiteness of modified cotton fabrics appeared moderately increasement.

The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

[Preparation and Photocatalytic Properties of Supported TiO2 Photocatalytic Material].

PubMed

Guo, Yu; Jin, Yu-jia; Wu, Hong-mei; Li, Dong-xin

2015-06-01

Titanium dioxide (TiO2) supported on spherical alumina substrate was prepared by using sol-gel method combined with dip-coating process. The surface morphology and structure of the synthesized samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) pattern. The results show that the morphology of the supported TiO2 composite material was obviously different from that of the original support. It reveals a layer formed by anatase TiO2 nanoparticles of 10-20 nm was deposited on the alumina substrate. Energy dispersive X-ray spectroscopy (EDX) analyses on the spherical alumina substrate and the resulting TiO2 composite catalyst were performed to determine the TiO2 loading content in the samples. It indicates that the TiO2 loading content on alumina substrate could be effectively increased by increasing the times of dip-coating alumina support in TiO2 sol. When dip-coating times increased to 5, the TiO2 loading content increased from 3.8 Wt. % to 15.7 Wt. %. In addition, the photocatalytic performances of the supported TiO2 materials prepared by different dip-coating times have been investigated by degrading methylene blue. It was found that the surface morphology of the supported TiO2 material was not only improved, but also the photocatalytic activity could be promoted significantly by increasing the dip-coating times. When the alumina substrate was dip-coated in TiO2 sol from 1 to 4 times, the degradation rate of methylene blue increased from 40% to 83.1%. However, after dip-coating the alumina support in TiO2 sol for 5 times, the degradation of methylene blue was only up to 85.6%. This indicates that the photocatalytic activity increased slowly when the TiO2 content in the supported catalyst was up to some extent. It is attributed to the continuous dip-coating resulted in less opportunities and weak intensity of illumination for the TiO2 nano-particles that under lower layer. The photocatalytic activity was relatively stable after repeated use of the supported TiO2 material for 5 times.

Fluorine-doping in titanium dioxide by ion implantation technique

NASA Astrophysics Data System (ADS)

Yamaki, T.; Umebayashi, T.; Sumita, T.; Yamamoto, S.; Maekawa, M.; Kawasuso, A.; Itoh, H.

2003-05-01

We implanted 200 keV F + in single crystalline titanium dioxide (TiO 2) rutile at a nominal fluence of 1 × 10 16 to 1 × 10 17 ions cm -2 and then thermally annealed the implanted sample in air. The radiation damage and its recovery process during the annealing were analyzed by Rutherford backscattering spectrometry in channeling geometry and variable-energy positron annihilation spectroscopy. The lattice disorder was completely recovered at 1200 °C by the migration of point defects to the surface. According to secondary ion mass spectrometry analysis, the F depth profile was shifted to a shallower region along with the damage recovery and this resulted in the formation of an F-doped layer where the impurity concentration steadily increased toward the surface. The F doping proved to provide a modification to the conduction-band edge of TiO 2, as assessed by theoretical band calculations.

TiO2 coatings via atomic layer deposition on polyurethane and polydimethylsiloxane substrates: Properties and effects on C. albicans growth and inactivation process

NASA Astrophysics Data System (ADS)

Pessoa, R. S.; dos Santos, V. P.; Cardoso, S. B.; Doria, A. C. O. C.; Figueira, F. R.; Rodrigues, B. V. M.; Testoni, G. E.; Fraga, M. A.; Marciano, F. R.; Lobo, A. O.; Maciel, H. S.

2017-11-01

Atomic layer deposition (ALD) surges as an attractive technology to deposit thin films on different substrates for many advanced biomedical applications. Herein titanium dioxide (TiO2) thin films were successful obtained on polyurethane (PU) and polydimethylsiloxane (PDMS) substrates using ALD. The effect of TiO2 films on Candida albicans growth and inactivation process were also systematic discussed. TiCl4 and H2O were used as precursors at 80 °C, while the reaction cycle number ranged from 500 to 2000. Several chemical, physical and physicochemical techniques were used to evaluate the growth kinetics, elemental composition, material structure, chemical bonds, contact angle, work of adhesion and surface morphology of the ALD TiO2 thin films grown on both substrates. For microbiological analyses, yeasts of standard strains of C. albicans were grown on non- and TiO2-coated substrates. Next, the antifungal and photocatalytic activities of the TiO2 were also investigated by counting the colony-forming units (CFU) before and after UV-light treatment. Chlorine-doped amorphous TiO2 films with varied thicknesses and Cl concentration ranging from 2 to 12% were obtained. In sum, the ALD TiO2 films suppressed the yeast-hyphal transition of C. albicans onto PU, however, a high adhesion of yeasts was observed. Conversely, for PDMS substrate, the yeast adhesion did not change, as observed in control. Comparatively to control, the TiO2-covered PDMS had a reduction in CFU up to 59.5% after UV treatment, while no modification was observed to TiO2-covered PU. These results pointed out that ALD chlorine-doped amorphous TiO2 films grown on biomedical polymeric surfaces may act as fungistatic materials. Furthermore, in case of contamination, these materials may also behave as antifungal materials under UV light exposure.

TiO2 and its composites as effective photocatalyst for glucose degradation processes

NASA Astrophysics Data System (ADS)

Kukh, A. A.; Ivanenko, I. M.; Astrelin, I. M.

2018-03-01

Titanium-dioxide photocatalyst was impregnated onto the activated carbon using originally developed low-temperature sol-gel method to form a TiO2:AC composite material. 15% (mass.) solution Ti2(SO4)3 in sulphuric acid was used as a precursor for photocatalyst synthesis. The highly effective composite material was obtained through a combination of properties of titanium dioxide and activated carbon. Synthesized composites TiO2 with activated carbon demonstrate highly developed surface characteristics and exhibit significantly higher activity in comparison with samples of pure TiO2 synthesized the same way, existing analogues of pure TiO2 synthesized from TiCl3 and even industrial photocatalyst. This was testified by the degradation of 1% aqueous glucose solution using TiO2:AC, samples of pure TiO2 and commercial TiO2 AEROXIDE® TiO2 P25 produced by EVONIK Industries.

Mini Review of TiO2 -Based Multifunctional Nanocomposites for Near-Infrared Light-Responsive Phototherapy.

PubMed

Wang, Meifang; Hou, Zhiyao; Al Kheraif, Abdulaziz A; Xing, Bengang; Lin, Jun

2018-06-25

Phototherapy with the properties of specific spatial/temporal selectivity and minimal invasiveness has been acknowledged as one of the most promising cancer therapy types. Among all the photoactive substance for phototherapy, titanium dioxide (TiO 2 ) nanomaterials are paid more and more attention due to their outstanding photocatalytic properties, prominent biocompatibility, and excellent chemical stability. However, the wide bandgap (3.0-3.2 eV) of TiO 2 limits its absorption only to the ultraviolet (UV) light region. For a long time, UV light-stimulated TiO 2 was applied in the phototherapy researches of tumors located in the skin layer, while it is unsatisfactory for most deep-tissue tumors. Due to the maximum penetration into tissue existing in the near-infrared (NIR) region, how to use NIR light to trigger photochemical reaction of TiO 2 remains a big challenge. In this review, two strategies to develop and construct NIR-triggered TiO 2 -based nanocomposites (NCs) for phototherapy are summarized, and the relevant mechanism and background knowledge of TiO 2 -based phototherapy are also given in order to better understand the application value and current situation of TiO 2 in phototherapy. Finally, the challenges and research directions of TiO 2 in the future clinic phototherapy application are also discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Combination of Efficient Perovskite Solar Cells with Low Temperature Processed Compact TiO2 Layer via Anodic Oxidation.

PubMed

Du, Yangyang; Cai, Hongkun; Wen, Hongbin; Wu, Yuxiang; Huang, Like; Ni, Jian; Li, Juan; Zhang, Jianjun

2016-05-25

In this work, a facile and low temperature processed anodic oxidation approach is proposed for fabricating compact and homogeneous titanium dioxide film (AO-TiO2). In order to realize morphology and thickness control of AO-TiO2, the theory concerning anodic oxidation (AO) is unveiled and the influence of relevant parameters during the process of AO such as electrolyte ingredient and oxidation voltage on AO-TiO2 formation is observed as well. Meanwhile, we demonstrate that the planar perovskite solar cells (p-PSCs) fabricated in ambient air and utilizing optimized AO-TiO2 as electron transport layer (ETL) can deliver repeatable power conversion efficiency (PCE) over 13%, which possess superior open-circuit voltage (Voc) and higher fill factor (FF) compared to its counterpart utilizing conventional high temperature processed compact TiO2 (c-TiO2) as ETL. Through a further comparative study, it is indicated that the improvement of device performance should be attributed to more effective electron collection from perovskite layer to AO-TiO2 and the decrease of device series resistance. Furthermore, hysteresis effect about current density-voltage (J-V) curves in TiO2-based p-PSCs is also unveiled.

High Sensitivity Refractometer Based on TiO2-Coated Adiabatic Tapered Optical Fiber via ALD Technology

PubMed Central

Zhu, Shan; Pang, Fufei; Huang, Sujuan; Zou, Fang; Guo, Qiang; Wen, Jianxiang; Wang, Tingyun

2016-01-01

Atomic layer deposition (ALD) technology is introduced to fabricate a high sensitivity refractometer based on an adiabatic tapered optical fiber. Different thicknesses of titanium dioxide (TiO2) nanofilm were coated around the tapered fiber precisely and uniformly under different deposition cycles. Attributed to the higher refractive index of the TiO2 nanofilm compared to that of silica, an asymmetric Fabry–Perot (F-P) resonator could be constructed along the fiber taper. The central wavelength of the F-P resonator could be controlled by adjusting the thickness of the TiO2 nanofilm. Such a F-P resonator is sensitive to changes in the surrounding refractive index (SRI), which is utilized to realize a high sensitivity refractometer. The refractometer developed by depositing 50.9-nm-thickness TiO2 on the tapered fiber shows SRI sensitivity as high as 7096 nm/RIU in the SRI range of 1.3373–1.3500. Due to TiO2’s advantages of high refractive index, lack of toxicity, and good biocompatibility, this refractometer is expected to have wide applications in the biochemical sensing field. PMID:27537885

Vacuum arc plasma deposition of thin titanium dioxide films on silicone elastomer as a functional coating for medical applications.

PubMed

Boudot, Cécile; Kühn, Marvin; Kühn-Kauffeldt, Marina; Schein, Jochen

2017-05-01

Silicone elastomer is a promising material for medical applications and is widely used for implants with blood and tissue contact. However, its strong hydrophobicity limits adhesion of tissue cells to silicone surfaces, which can impair the healing process. To improve the biological properties of silicone, a triggerless pulsed vacuum cathodic arc plasma deposition technique was applied to deposit titanium dioxide (TiO 2 ) films onto the surface. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and contact angle measurements were used for coating characterization. Deposited films were about 150nm thick and exhibited good adhesion to the underlying silicone substrate. Surface wettability and roughness both increased after deposition of the TiO 2 layer. In addition, cell-biological investigations demonstrated that the in-vitro cytocompatibility of TiO 2 -coated samples was greatly improved without impacting silicone's nontoxicity. For validation of use in medical devices, further investigations were conducted and demonstrated stability of surface properties in an aqueous environment for a period of 68days and the coating's resistance to several sterilization methods. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanical Grinding Preparation and Characterization of TiO2-Coated Wollastonite Composite Pigments

PubMed Central

Chen, Wanting; Liang, Yu; Hou, Xifeng; Zhang, Jing; Ding, Hao; Sun, Sijia; Cao, Hu

2018-01-01

TiO2-coated wollastonite composite pigments were prepared by the mechano-chemical grinding of wollastonite and TiO2 powder together in a wet ultrafine stirred mill. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and infrared spectra were used to investigate the microstructures and morphologies of the composite and the reaction mechanism. The results indicate that the TiO2-coated wollastonite composite pigments have similar properties to titanium dioxide pigment, showing much better properties than dry and wet mixing of wollastonite and TiO2. The hiding power of TiO2-coated wollastonite composite pigments (45% TiO2) is 17.97 g/m2, reaching 81.08% of titanium dioxide. A firm combination between wollastonite and TiO2 is obtained through a surface dehydroxylation reaction during the mechano-chemical method. PMID:29649116

Development of SPR temperature sensor using Au/TiO2 on hetero-core optical fiber

NASA Astrophysics Data System (ADS)

Kitagawa, Sho; Yamazaki, Hiroshi; Hosoki, Ai; Nishiyama, Michiko; Watanabe, Kazuhiro

2016-03-01

This paper describes a novel temperature sensor based on a hetero-core structured fiber optic surface plasmon resonance (SPR) sensor with multi-layer thin film of gold (Au) and titanium dioxide (TiO2). Temperature condition is an essential parameter in chemical plants for avoiding fire accident and controlling qualities of chemical substances. Several fiber optic temperature sensors have been developed for some advantages such as immunity to electromagnetic interference, corrosion resistance and no electrical leakage. The proposed hetero-core fiber optic SPR sensor detects temperature condition by measuring slight refractive index changes of TiO2 which has a large thermo-optic coefficient. We experimentally confirmed that the SPR resonant wavelength in the hetero-core SPR sensor with coating an Au film which slightly depended on temperature changes in the range from 20 °C to 80 °C. In addition, it was experimentally shown that the proposed SPR temperature sensor with multi-layer film of Au and TiO2 had the SPR resonant wavelength shift of 1.6 nm due to temperature change from -10 °C to 50 °C. As a result, a series of experiments successfully demonstrated that the proposed sensor was able to detect temperature directly depending on the thermo-optic effect of TiO2.

Polarization-Dependent Raman Spectroscopy of Epitaxial TiO 2 (B) Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jokisaari, Jacob R.; Bayerl, Dylan; Zhang, Kui

2015-12-08

The bronze polymorph of titanium dioxide, known as TiO 2(B), has promising photochemical and electronic properties for potential applications in Li-ion batteries, photocatalysis, chemical sensing, and solar cells. In contrast to previous studies performed with powder samples, which often suffer from impurities and lattice water, here we report Raman spectra from highly crystalline TiO 2(B) films epitaxially grown on Si substrates with a thin SrTiO 3 buffer layer. The reduced background from the Si substrate significantly benefits acquisition of polarization-dependent Raman spectra collected from the high-quality thin films, which are compared to nanopowder results reported in the literature. The experimentalmore » spectra were compared with density functional theory calculations to analyze the atomic displacements associated with each Raman-active vibrational mode. These results provide a standard reference for further investigation of the crystallinity, structure, composition, and properties of TiO 2(B) materials with Raman spectroscopy.« less

Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

PubMed

Nemati, Sima Hashemi; Hadjizadeh, Afra

2017-08-01

Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO 2 ) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO 2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO 2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO 2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO 2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

Fabrication of Gold-coated 3-D Woodpile Structures for Mid-IR Thermal Emitters

NASA Astrophysics Data System (ADS)

Li, Shengkai; Moridani, Amir; Kothari, Rohit; Lee, Jae-Hwang; Watkins, James

3-D metallic woodpile nanostructures possess enhancements in thermal radiation that are both wavelength and polarization specific and are promising for thermal-optical devices for various applications including thermal photovoltaics, self-cooling devices, and chemical and bio-sensors. However, current fabrication techniques for such structures are limited by slow speed, small area capability, the need for expensive facilities and, in general, are not suitable for high-throughput mass production. Here we demonstrate a new strategy for the fabrication of 3D metallic woodpile structures. Well-defined TiO2 woodpile structures were fabricated using a layer-by-layer nanoimprint method using TiO2 nanoparticle ink dispersions. The TiO2 woodpile was then coated with a high purity, conformal gold film via reactive deposition in supercritical carbon dioxide. The final gold-coated woodpile structures exhibit strong spectral and polarization specific thermal emission enhancements. The fabrication method demonstrated here is promising for high-throughput, low-cost preparation of 3D metallic woodpile structures and other 3D nanostructures. Center for Hierarchical Manufacturing, NSF.

Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness

PubMed Central

Smijs, Threes G; Pavel, Stanislav

2011-01-01

Sunscreens are used to provide protection against adverse effects of ultraviolet (UV)B (290–320 nm) and UVA (320–400 nm) radiation. According to the United States Food and Drug Administration, the protection factor against UVA should be at least one-third of the overall sun protection factor. Titanium dioxide (TiO2) and zinc oxide (ZnO) minerals are frequently employed in sunscreens as inorganic physical sun blockers. As TiO2 is more effective in UVB and ZnO in the UVA range, the combination of these particles assures a broad-band UV protection. However, to solve the cosmetic drawback of these opaque sunscreens, microsized TiO2 and ZnO have been increasingly replaced by TiO2 and ZnO nanoparticles (NPs) (<100 nm). This review focuses on significant effects on the UV attenuation of sunscreens when microsized TiO2 and ZnO particles are replaced by NPs and evaluates physicochemical aspects that affect effectiveness and safety of NP sunscreens. With the use of TiO2 and ZnO NPs, the undesired opaqueness disappears but the required balance between UVA and UVB protection can be altered. Utilization of mixtures of micro- and nanosized ZnO dispersions and nanosized TiO2 particles may improve this situation. Skin exposure to NP-containing sunscreens leads to incorporation of TiO2 and ZnO NPs in the stratum corneum, which can alter specific NP attenuation properties due to particle–particle, particle–skin, and skin–particle–light physicochemical interactions. Both sunscreen NPs induce (photo)cyto- and genotoxicity and have been sporadically observed in viable skin layers especially in case of long-term exposures and ZnO. Photocatalytic effects, the highest for anatase TiO2, cannot be completely prevented by coating of the particles, but silica-based coatings are most effective. Caution should still be exercised when new sunscreens are developed and research that includes sunscreen NP stabilization, chronic exposures, and reduction of NPs’ free-radical production should receive full attention. PMID:24198489

Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

PubMed

Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

2016-02-01

This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

Effects of porous films on the light reflectivity of pigmentary titanium dioxide particles

NASA Astrophysics Data System (ADS)

Liang, Yong; Qiao, Bing; Wang, Tig-Jie; Gao, Han; Yu, Keyi

2016-11-01

The light reflectivity of the film-coated titanium dioxide particles (TiO2) as a function of the film refractive index was derived and calculated using a plane film model. For the refractive index in the range of 1.00-2.15, the lower the film refractive index is, the higher is the light reflectivity of the film. It is inferred that the lower apparent refractive index of the porous film resulted in the higher reflectivity of light, i.e., the higher hiding power of the titanium dioxide particles. A dense film coating on TiO2 particles with different types of oxides, i.e., SiO2, Al2O3, MgO, ZnO, ZrO2, TiO2, corresponding to different refractive indices of the film from 1.46 to 2.50, was achieved, and the effects of refractive index on the hiding power from the model prediction were confirmed. Porous film coating of TiO2 particles was achieved by adding the organic template agent triethanolamine (TEA). The hiding power of the coated TiO2 particles was increased from 88.3 to 90.8 by adding the TEA template to the film coating (5-20 wt%). In other words, the amount of titanium dioxide needed was reduced by approximately 10% without a change in the hiding power. It is concluded that the film structure coated on TiO2 particle surface affects the light reflectivity significantly, namely, the porous film exhibits excellent performance for pigmentary titanium dioxide particles with high hiding power.

The formation of titanium dioxide crystallite nanoparticles during activation of PAN nanofibers containing titanium isopropoxide

NASA Astrophysics Data System (ADS)

Mehrpouya, Fahimeh; Tavanai, Hossein; Morshed, Mohammad; Ghiaci, Mehran

2012-08-01

Activated carbon (AC) can act as an important carrier for TiO2 nanoparticles. TiO2 nanoparticle can be fabricated by the hydrolysis and condensation of titanium alkoxides like titanium isopropoxide. This study showed that the formation of titanium dioxide crystallite nanoparticle during activation of PAN nanofibers containing titanium isopropoxide leads to the formation of mainly anatase crystal TiO2 nanoparticle in AC nanofibers, with a good dispersion in both the longitude and cross section of nanofibers. The TiO2 crystallite size lies in the range of 7.3-11.3 nm. The dispersion of TiO2 nanoparticles in the matrix of AC nanofibers is far superior to the direct mixing of TiO2 nanoparticles in the original electrospinning solution.

Combined Study of Titanium Dioxide Nanoparticle Transport and Toxicity on Microbial Nitrifying Communities under Single and Repeated Exposures in Soil Columns.

PubMed

Simonin, Marie; Martins, Jean M F; Uzu, Gaëlle; Vince, Erwann; Richaume, Agnès

2016-10-04

Soils are exposed to nanoparticles (NPs) as a result of their increasing use in many commercial products. Adverse effects of NPs on soil microorganisms have been reported in several ecotoxicological studies using microcosms. Although repeated exposures are more likely to occur in soils, most of these previous studies were performed as a single exposure to NPs. Contrary to single contamination, the study of multiple NP contaminations in soils requires the use of specialized setups. Using a soil column experiment, we compared the influence of single and repeated exposures (one, two, or three exposures that resulted in the same final concentration applied) on the transport of titanium dioxide (TiO 2 ) NPs through soil and the effect of these different exposure scenarios on the abundance and activity of soil nitrifying microbial communities after a 2 month incubation. The transport of TiO 2 NPs was very limited under both single and repeated exposures and was highest for the lowest concentration injected during the first application. Significant decreases in nitrification activity and ammonia-oxidizing archaea and bacteria populations were observed only for the repeated exposure scenario (three TiO 2 NP contaminations). These results suggest that, under repeated exposures, the transport of TiO 2 NPs to deep soil layers and groundwater is limited and that a chronic contamination is more harmful for the soil microbiological functioning than a single exposure.

The Effects of Biopolymers Composite Based Waste Cooking Oil and Titanium Dioxide Fillers as Superhydrophobic Coatings.

NASA Astrophysics Data System (ADS)

Marsi, N.; Rus, A. Z. M.

2017-08-01

This project presents the effect of biopolymer composite surface coating on TiO2 fillers by analysing the static water contact angle, SEM micrographs, porosity, density and refractive index of biopolymer doped with different loading of TiO2. The different ratio loading of 0.5, 1.0, 1.5, 2.0 and 2.5 (wt/wt%) TiO2 can be used to improve the material properties in practical use for outdoor application especially to enhance the stability of surface coating. It is found that the smooth surfaces with a low ratio loading of TiO2 fillers on biopolymer composite surface coating increases the static water contact angle up to 162.29°. It is interpreted with respect to nano- features existing on the surface of the water repellent creates a thin superhydrphobic layer. The relationship between porosity and density is indirectly proportional where the higher the loading of TiO2 filler produce the lower porosity up to 0.86% of the surface coating. The movement from shorter to longer of wavelength was observed before and after exposure indicates that there are optimization of absorption of UV-B radiation as the amount of delocalisation.

Core-shell titanium dioxide-titanium nitride nanotube arrays with near-infrared plasmon resonances

NASA Astrophysics Data System (ADS)

Farsinezhad, Samira; Shanavas, Thariq; Mahdi, Najia; Askar, Abdelrahman M.; Kar, Piyush; Sharma, Himani; Shankar, Karthik

2018-04-01

Titanium nitride (TiN) is a ceramic with high electrical conductivity which in nanoparticle form, exhibits localized surface plasmon resonances (LSPRs) in the visible region of the solar spectrum. The ceramic nature of TiN coupled with its dielectric loss factor being comparable to that of gold, render it attractive for CMOS polarizers, refractory plasmonics, surface-enhanced Raman scattering and a whole host of sensing applications. We report core-shell TiO2-TiN nanotube arrays exhibiting LSPR peaks in the range 775-830 nm achieved by a simple, solution-based, low cost, large area-compatible fabrication route that does not involve laser-writing or lithography. Self-organized, highly ordered TiO2 nanotube arrays were grown by electrochemical anodization of Ti thin films on fluorine-doped tin oxide-coated glass substrates and then conformally coated with a thin layer of TiN using atomic layer deposition. The effects of varying the TiN layer thickness and thermal annealing on the LSPR profiles were also investigated. Modeling the TiO2-TiN core-shell nanotube structure using two different approaches, one employing effective medium approximations coupled with Fresnel coefficients, resulted in calculated optical spectra that closely matched the experimentally measured spectra. Modeling provided the insight that the observed near-infrared resonance was not collective in nature, and was mainly attributable to the longitudinal resonance of annular nanotube-like TiN particles redshifted due to the presence of the higher permittivity TiO2 matrix. The resulting TiO2-TiN core-shell nanotube structures also function as visible light responsive photocatalysts, as evidenced by their photoelectrochemical water-splitting performance under light emitting diode illumination using 400, 430 and 500 nm photons.

A strategy of combining SILAR with solvothermal process for In2S3 sensitized quantum dot-sensitized solar cells

NASA Astrophysics Data System (ADS)

Yang, Peizhi; Tang, Qunwei; Ji, Chenming; Wang, Haobo

2015-12-01

Pursuit of an efficient strategy for quantum dot-sensitized photoanode has been a persistent objective for enhancing photovoltaic performances of quantum dot-sensitized solar cell (QDSC). We present here the fabrication of the indium sulfide (In2S3) quantum dot-sensitized titanium dioxide (TiO2) photoanode by combining successive ionic layer adsorption and reaction (SILAR) with solvothermal processes. The resultant QDSC consists of an In2S3 sensitized TiO2 photoanode, a liquid polysulfide electrolyte, and a Co0.85Se counter electrode. The optimized QDSC with photoanode prepared with the help of a SILAR method at 20 deposition cycles and solvothermal method yields a maximum power conversion efficiency of 1.39%.

Two-Functional Direct Current Sputtered Silver-Containing Titanium Dioxide Thin Films

NASA Astrophysics Data System (ADS)

Musil, J.; Louda, M.; Cerstvy, R.; Baroch, P.; Ditta, I. B.; Steele, A.; Foster, H. A.

2009-04-01

The article reports on structure, mechanical, optical, photocatalytic and biocidal properties of Ti-Ag-O films. The Ti-Ag-O films were reactively sputter-deposited from a composed Ti/Ag target at different partial pressures of oxygen p_{O2} on unheated glass substrate held on floating potential U fl. It was found that addition of 2 at.% of Ag into TiO2 film has no negative influence on UV-induced hydrophilicity of TiO2 film. Thick ( 1,500 nm) TiO2/Ag films containing (200) anatase phase exhibit the best hydrophilicity with water droplet contact angle (WDCA) lower than 10° after UV irradiation for 20 min. Thick ( 1,500 nm) TiO2/Ag films exhibited a better UV-induced hydrophilicity compared to that of thinner ( 700 nm) TiO2/Ag films. Further it was found that hydrophilic TiO2/Ag films exhibit a strong biocidal effect under both the visible light and the UV irradiation with 100% killing efficiency of Escherichia coli ATCC 10536 after UV irradiation for 20 min. Reported results show that single layer of TiO2 with Ag distributed in its whole volume exhibits, after UV irradiation, simultaneously two functions: (1) excellent hydrophilicity with WDCA < 10° and (2) strong power to kill E. coli even under visible light due to direct toxicity of Ag.

One-Pot Synthesis of Reduced Graphene Oxide/Anatase Titanium Dioxide Composites for Photocatalytic Degradation of Methylene Blue.

PubMed

Lee, Hyo In; Park, Soo-Jin

2018-09-01

In this work, highly ordered TiO2-reduced graphene oxide sheets (TGS) were successfully fabricated via a one-pot solvothermal method with different amounts of graphene oxide (0.01, 0.03, 0.05, and 0.07 g). This was achieved by reacting graphene oxide (GO) layers with titanium isopropoxide as the TiO2 precursor. The TGS exhibited superior efficiency compared to pristine TiO2 and the best results were recorded for the TGS-0.05 sample. The presence of the reduced graphene oxide (rGO) component was determined to be an important factor governing the separation of the photogenerated electron-hole pair via interfacial charge transfer. The significantly increased activity of the TGS under simulated solar light in the degradation of methylene blue (MB) indicates that these materials are promising photocatalysts for efficient water purification.

ZnO and TiO2 particles: a study on nanosafety and photoprotection

NASA Astrophysics Data System (ADS)

Popov, Alexey; Zhao, Xin; Zvyagin, Andrei; Lademann, Jürgen; Roberts, Michael; Sanchez, Washington; Priezzhev, Alexander; Myllylä, Risto

2010-04-01

Nanoparticles of titanium dioxide (TiO2) and zinc oxide (ZnO) are used in sunscreens as protective compounds against UV radiation. We investigate these particles from the viewpoint of nanosafety (penetration into skin in vivo, production of free radicals when UV-irradiated) as well as UV protection. We show that: a) even after multiple applications, the particles remain within stratum corneum (uppermost skin layer); b) the optimal sizes are 62 nm and 45 nm, respectively for TiO2 and ZnO particles for 310-nm light and, correspondingly, 122 and 140 nm - for 400-nm radiation; c) in general, small particles (25 nm in diameter) are more photoactive than the larger ones (400 nm in diameter); however, on the background if porcine skin in vitro this difference is not seen and is substantially surpassed by skin contribution into production of free radicals.

Mechanism of room temperature oxygen sensor based on nanocrystalline TiO2 film

NASA Astrophysics Data System (ADS)

Bakri, A. S.; Sahdan, M. Z.; Nafarizal, N.; Abdullah, S. A.; Said, N. D. M.; Raship, N. A.; Sari, Y.

2018-04-01

A titanium dioxide (TiO2) thin film is proposed as the active layer for the detection of oxygen gas. The sensor is fabricated on silicon wafer using sol-gel dip coating technique with a constant withdrawal speed. The field emission scanning electron microscope image reveals that the film has a uniform structure while the x-ray diffraction analysis indicates that the film is anatase phase with tetragonal lattice structure. The film exhibit the highest intensity peak at (101) plane. The surface roughness measurement shows that the film has low surface roughness with small grain size. The electrical studies revealed that the resistivity is about 4.02 x 10-3 Ω.cm and the thickness of TiO2 film is 127.44 nm. The gas sensor measurement showed that the sensor response of the film is about 4.21% at room temperature.

Morphology and thermal stability of nano titanium dioxide filled natural rubber prepared by latex mixing method

NASA Astrophysics Data System (ADS)

Hayeemasae, N.; Surya, I.; Ismail, H.

2018-02-01

This paper deals with the morphology and thermal stability of nano Titanium Dioxide (TiO2) filled natural rubber composites. This study also suggests a new method of incorporating TiO2. Aqueous dispersions of nano TiO2at the loadings of 0, 2, 4, 6 and 8 phr were dispersed in natural rubber latex, the resulting compounds were then dried prior to mixing it with other ingredients on a two-roll mill. By applying this technique, the homogeneity of the compound is significantly improved. This can be clearly seen from the morphology observed. Adding TiO2 results in shifting the decomposition temperature and char residue irrespective of the loadings of nano TiO2.

A thin porous substrate using bonded particles for reverse-emulsion electrophoretic displays

NASA Astrophysics Data System (ADS)

Ahumada, M.; Bryning, M.; Cromer, R.; Hartono, M.; Lee, S. J.

2012-03-01

A thin porous layer of bonded ceramic microparticles has been developed to provide structural integrity and a stationary matrix for use in reflective-mode reverse-emulsion electrophoretic displays (REED), based on self-assembled nanodroplets dispersed in a non-polar liquid. REED ink uses low-cost materials and manufacturing processes, yet is capable of video speed and low voltage operation below 10 V. Porous layers of titanium dioxide (TiO2) are prepared as thin as 10 microns by fluidizing the particles in a water-based slurry with polymeric adhesive. The slurry is distributed between glass shear plates, one of which serves as the substrate for the working device. Particle morphology is examined using scanning electron microscopy and layer uniformity is characterized by opacity measurements using a throughbeam fiber optic sensor. Performance of the bonded matrix with REED ink is compared to baseline performance of a paste mixture, comprised of the same ink and unbonded TiO2 particles. Results show that at 25% volume fraction, the bonded substrate improves image bistability and is better able to maintain both light and dark intensity after extensive switching. The same bonded substrate also improves image bistability when power is disconnected, even compared to a paste with 40% volume fraction of TiO2.

Interaction of titanium dioxide nanoparticles with glucose on young rats after oral administration.

PubMed

Chen, Zhangjian; Wang, Yun; Zhuo, Lin; Chen, Shi; Zhao, Lin; Chen, Tian; Li, Yang; Zhang, Wenxiao; Gao, Xin; Li, Ping; Wang, Haifang; Jia, Guang

2015-10-01

Titanium dioxide nanoparticles (TiO2 NPs) have a broad application prospect in replace with TiO2 used as a food additive, especially used in sweets. Understanding the interaction of TiO2 NPs with sugar is meaningful for health promotion. We used a young animal model to study the toxicological effect of orally administrated TiO2 NPs at doses of 0, 2, 10 and 50 mg/kg per day with or without daily consumption of 1.8 g/kg glucose for 30 days and 90 days. The results showed that oral exposure to TiO2 NPs and TiO2 NPs+glucose both induced liver, kidney, and heart injuries as well as changes in the count of white and red blood cells in a dose, time and gender-dependent manner. The toxicological interactions between orally-administrated TiO2 NPs and glucose were evident, but differed among target organs. These results suggest that it is necessary to limit dietary co-exposure to TiO2 NPs and sugar. Nanotechnology has gained entrance in the food industry, with the presence of nanoparticles now in many food items. Despite this increasing trend, the potential toxic effects of these nanoparticles to human remain unknown. In this article, the authors studied titanium dioxide nanoparticles (TiO2 NPs), which are commonly used as food additive, together with glucose. The findings of possible adverse effects on liver, kidney, and heart might point to a rethink of using glucose and TiO2 NPs combination. Copyright © 2015 Elsevier Inc. All rights reserved.

The influence of corneocyte structure on the interpretation of permeation profiles of nanoparticles across skin

NASA Astrophysics Data System (ADS)

Pinheiro, T.; Pallon, J.; Alves, L. C.; Veríssimo, A.; Filipe, P.; Silva, J. N.; Silva, R.

2007-07-01

The permeability of skin to nanoparticles of titanium dioxide (TiO 2) used in sunscreens as a reflector of the UV wavelengths of sunlight, was examined using nuclear microscopy techniques. Special attention was given to the permeation characteristics of these nanoparticles across the outer layers of skin, the stratum corneum, in healthy and psoriatic skin condition. Aspects that may influence the interpretation of results such as sample preparation difficulties and skin condition were focused. Sample preparation can damage the integrity of the corneocyte layers inducing unwanted artefacts that may bias the evaluation of results. Irradiation conditions may also introduce distortions in the labile structures of human skin. Skin condition, such as loss of corneocyte cohesion occurring in psoriasis also influence the permeation profile of the nanoparticles. Weighing and accounting for these features in the examination of skin by nuclear microscopy is crucial to accurately assess the TiO 2 nanoparticles permeation depth.

Stoichiometric titanium dioxide ion implantation in AISI 304 stainless steel for corrosion protection

NASA Astrophysics Data System (ADS)

Hartwig, A.; Decker, M.; Klein, O.; Karl, H.

2015-12-01

The aim of this study is to evaluate the applicability of highly chemically inert titanium dioxide synthesized by ion beam implantation for corrosion protection of AISI 304 stainless steel in sodium chloride solution. More specifically, the prevention of galvanic corrosion between carbon-fiber reinforced plastic (CFRP) and AISI 304 was investigated. Corrosion performance of TiO2 implanted AISI 304 - examined for different implantation and annealing parameters - is strongly influenced by implantation fluence. Experimental results show that a fluence of 5 × 1016 cm-2 (Ti+) and 1 × 1017 cm-2 (O+) is sufficient to prevent pitting corrosion significantly, while galvanic corrosion with CFRP can already be noticeably reduced by an implantation fluence of 5 × 1015 cm-2 (Ti+) and 1 × 1016 cm-2 (O+). Surface roughness, implantation energy and annealing at 200 °C and 400 °C show only little influence on the corrosion behavior. TEM analysis indicates the existence of stoichiometric TiO2 inside the steel matrix for medium fluences and the formation of a separated metal oxide layer for high fluences.

Photocatalytic Degradation Effect of μ-Dielectric Barrier Discharge Plasma Treated Titanium Dioxide Nanoparticles on Environmental Contaminant.

PubMed

Seo, Hyeon Jin; Hwang, Ki-Hwan; Na, Young Hoon; Boo, Jin-Hyo

2018-09-01

This study focused on the photocatalytic degradation effect of the μ-dielectric barrier discharge (μ-DBD) plasma treated titanium dioxide (TiO2) nanoparticles on environmental contaminant such as formaldehyde. TiO2 nanoparticles were treated by a μ-DBD plasma source with nitrogen gas. We analyzed the degradation of formaldehyde with the plasma treated TiO2 nanoparticles by UV-visible spectrophotometer (UV-VIS), and demonstrated that the photocatalytic activity of the μ-DBD plasma-treated TiO2 nanoparticles showed significantly high catalytic efficiency rather than without plasma treated TiO2 nanoparticles. Field emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle analyzer were used to measure the effects of photocatalytic degradation for the plasma treated TiO2 nanoparticles.

Synthesis and Characterization of Titanium Dioxide Thin Film for Sensor Applications

NASA Astrophysics Data System (ADS)

Latha, H. K. E.; Lalithamba, H. S.

2018-03-01

Titanium oxide (TiO2) nanoparticles (metal oxide semiconductor) are successfully synthesized using hydrothermal method for sensor application. Titanium dioxide and Sodium hydroxide are used as precursors. These reactants are mixed and calcinated at 400 °C to produce TiO2 nanoparticles. The crystalline structure, morphology of synthesized TiO2 nanoparticles are studied using x-ray diffraction (XRD), Fourier Transform Infrared (FTIR) analysis and scanning electron microscopy (SEM). XRD results revealed that the prepared TiO2 sample is highly crystalline, having Anatase crystal structure. FT-IR spectra peak at 475 cm‑1 indicated characteristic absorption bands of TiO2 nanoparticles. The XRD and FTIR result confirmed the formation of high purity of TiO2 nanoparticles. The SEM image shows that TiO2 nanoparticles prepared in this study are spherical in shape. Synthesized TiO2 nanoparticles are deposited on glass substrate at room temperature using E beam evaporation method to determine gauge factor and found to be 4.7. The deposited TiO2 thin films offer tremendous potential in the applications of electronic and magneto–electric devices.

Reusable photocatalytic titanium dioxide-cellulose nanofiber films

Treesearch

Alexandra Snyder; Zhenyu Bo; Robert Moon; Jean-Christophe Rochet; Lia Stanciu

2013-01-01

Titanium dioxide (TiO2) is a well-studied photocatalyst that is known to break down organic molecules upon ultraviolet (UV) irradiation. Cellulose nanofibers (CNFs) act as an attractive matrix material for the suspension of photocatalytic particles due to their desirable mechanical and optical properties. In this work, TiO2...

TiO2 Processed by pressurized hot solvents as a novel photocatalyst for photocatalytic reduction of carbon dioxide

NASA Astrophysics Data System (ADS)

Reli, Martin; Kobielusz, Marcin; Matějová, Lenka; Daniš, Stanislav; Macyk, Wojciech; Obalová, Lucie; Kuśtrowski, Piotr; Rokicińska, Anna; Kočí, Kamila

2017-01-01

Anatase-brookite TiO2 photocatalysts were prepared by the sol-gel process controlled within reverse micelles and processing by pressurized hot solvents-water/methanol/water (TiO2(M)) and water/ethanol/water (TiO2(E)), as an unconventional alternative to common calcination. The main goal of this work was to prepare anatase-brookite mixtures by processing by two different alcohols (methanol and ethanol) and evaluate the influence of the alcohol on the photocatalytic activity. Prepared photocatalysts were characterized by organic elemental analysis, nitrogen physisorption, XRD, UV-vis, photoelectrochemical and spectroelectrochemical measurements and XPS. The prepared photocatalysts efficiency was tested on the photocatalytic reduction of carbon dioxide and compared with commercial TiO2 Evonik P25. Both prepared nanocomposites were more efficient towards methane production but Evonik P25 was the most efficient towards hydrogen generated through water splitting. The higher performance of anatase-brookite mixture towards methane production can be explained by (i) a higher photocatalytic activity of brookite than rutile; (ii) a large surface area of anatase-brookite composites enabling better carbon dioxide adsorption; (iii) the photoinduced electron transfer from the brookite conduction band to the anatase conduction band. On the other hand, a higher production of hydrogen in the presence of Evonik P25 is caused by a better charge separation in anatase-rutile than anatase-brookite phase compositions. TiO2(M) appeared more active than TiO2(E) in the photocatalytic reduction of carbon dioxide due to a lower density of defects created in the crystal lattice.

Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light

NASA Astrophysics Data System (ADS)

Tanabe, Ichiro; Kurawaki, Yuji

2018-05-01

Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤ 200 nm) region of titanium dioxide (TiO2) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO2 under visible light, respectively.

Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells.

PubMed

Ananth, S; Vivek, P; Arumanayagam, T; Murugakoothan, P

2014-07-15

Natural dye extract of lawsonia inermis seed were used as photo sensitizer to fabricate titanium dioxide nanoparticles based dye sensitized solar cells. Pure titanium dioxide (TiO2) nanoparticles in anatase phase were synthesized by sol-gel technique and pre dye treated TiO2 nanoparticles were synthesized using modified sol-gel technique by mixing lawsone pigment rich natural dye during the synthesis itself. This pre dye treatment with natural dye has yielded colored TiO2 nanoparticles with uniform adsorption of natural dye, reduced agglomeration, less dye aggregation and improved morphology. The pure and pre dye treated TiO2 nanoparticles were subjected to structural, optical, spectral and morphological studies. Dye sensitized solar cells (DSSC) fabricated using the pre dye treated and pure TiO2 nanoparticles sensitized by natural dye extract of lawsonia inermis seed showed a promising solar light to electron conversion efficiency of 1.47% and 1% respectively. The pre dye treated TiO2 based DSSC showed an improved efficiency of 47% when compared to that of conventional DSSC. Copyright © 2014 Elsevier B.V. All rights reserved.

Surface Acidity and Properties of TiO2/SiO2 Catalysts Prepared by Atomic Layer Deposition: UV-visible Diffuse Reflectance, DRIFTS, and Visible Raman Spectroscopy Studies

DTIC Science & Technology

2009-06-15

titanium isopropoxide (TTIP) as metal precursors. The deposition rate of titania films from TiCl4 was found to be stable in the 150-300 °C...tetrachloride (TiCl4) and titanium isopropoxide (TTIP) are widely used as metal precursors and water or hydrogen peroxide are used as oxygen precursors.29-36... titanium dioxide supported on high surface area silica gel have been synthesized by atomic layer deposition (ALD) using titanium tetrachloride (TiCl4) and

Titanium Dioxide Nanoparticle Penetration into the Skin and Effects on HaCaT Cells

PubMed Central

Crosera, Matteo; Prodi, Andrea; Mauro, Marcella; Pelin, Marco; Florio, Chiara; Bellomo, Francesca; Adami, Gianpiero; Apostoli, Pietro; De Palma, Giuseppe; Bovenzi, Massimo; Campanini, Marco; Larese Filon, Francesca

2015-01-01

Titanium dioxide nanoparticles (TiO2NPs) suspensions (concentration 1.0 g/L) in synthetic sweat solution were applied on Franz cells for 24 h using intact and needle-abraded human skin. Titanium content into skin and receiving phases was determined. Cytotoxicity (MTT, AlamarBlue® and propidium iodide, PI, uptake assays) was evaluated on HaCat keratinocytes after 24 h, 48 h, and seven days of exposure. After 24 h of exposure, no titanium was detectable in receiving solutions for both intact and damaged skin. Titanium was found in the epidermal layer after 24 h of exposure (0.47 ± 0.33 μg/cm2) while in the dermal layer, the concentration was below the limit of detection. Damaged skin, in its whole, has shown a similar concentration (0.53 ± 0.26 μg/cm2). Cytotoxicity studies on HaCaT cells demonstrated that TiO2NPs induced cytotoxic effects only at very high concentrations, reducing cell viability after seven days of exposure with EC50s of 8.8 × 10−4 M (MTT assay), 3.8 × 10−5 M (AlamarBlue® assay), and 7.6 × 10−4 M (PI uptake, index of a necrotic cell death). Our study demonstrated that TiO2NPs cannot permeate intact and damaged skin and can be found only in the stratum corneum and epidermis. Moreover, the low cytotoxic effect observed on human HaCaT keratinocytes suggests that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure. PMID:26262634

Biomolecule-controlled hydrothermal synthesis of C-N-S-tridoped TiO2 nanocrystalline photocatalysts for NO removal under simulated solar light irradiation.

PubMed

Wang, Yawen; Huang, Yu; Ho, Wingkei; Zhang, Lizhi; Zou, Zhigang; Lee, Shuncheng

2009-09-30

In this study, C-N-S-tridoped titanium dioxide (TiO(2)) nanocrystals were synthesized by using a facile hydrothermal method in the presence of a biomolecule l-cysteine. This biomolecule could not only serve as the common source for the carbon, sulfur and nitrogen tridoping, but also could control the final crystal phases and morphology. The resulting materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption and UV-vis diffuse reflectance spectroscopy. XPS analysis revealed that S was incorporated into the lattice of TiO(2) through substituting oxygen atoms, N might coexist in the forms of N-Ti-O and Ti-O-N in tridoped TiO(2) and most C could form a mixed layer of carbonate species deposited on the surface of TiO(2) nanoparticles. The photocatalytic activities of the samples were tested on the removal of NO at typical indoor air level in a flow system under simulated solar light irradiation. The tridoped TiO(2) samples showed much higher removal efficiency than commercial P25 and the undoped counterpart photocatalyst. The enhanced visible light photocatalytic activity of C-N-S-tridoped TiO(2) nanocrystals was explained on the basis of characterizations. The possible formation process of the monodispersed C-N-S-tridoped anatase TiO(2) nanocrystals was also proposed. This study provides a new method to prepare visible light active TiO(2) photocatalyst.

Growth behaviors and biocidal properties of titanium dioxide films depending on nucleation duration in liquid phase deposition

NASA Astrophysics Data System (ADS)

Park, Sohyeon; Park, Joohee; Heo, Jiwoong; Hong, Bo Young; Hong, Jinkee

2017-12-01

Liquid phase deposition (LPD), which is a method to directly form a titanium dioxide (TiO2) film on a substrate, is the most practical method for applying TiO2 films to medical devices because it is performed at lower temperatures than other methods. The TiO2 films to be applied to medical devices should offer excellent antibacterial effect, but should be stable to normal cells and have appropriate strength. In this research, we observed that the size, shape, and density of TiO2 particles varied with the nucleation duration in LPD and confirmed that these results caused changes in several properties including the mechanical properties, cytotoxicity and antibacterial effect of TiO2 films. From the analysis of these results, we established the conditions for the preparation of TiO2 films that are suitable for medical devices and suggest a new approach to the study of TiO2 films prepared by LPD.

Effects of Titanium Dioxide Nanoparticles on Red Clover and Its Rhizobial Symbiont.

PubMed

Moll, Janine; Okupnik, Annette; Gogos, Alexander; Knauer, Katja; Bucheli, Thomas D; van der Heijden, Marcel G A; Widmer, Franco

2016-01-01

Titanium dioxide nanoparticles (TiO2 NPs) are in consideration to be used in plant protection products. Before these products can be placed on the market, ecotoxicological tests have to be performed. In this study, the nitrogen fixing bacterium Rhizobium trifolii and red clover were exposed to two TiO2 NPs, i.e., P25, E171 and a non-nanomaterial TiO2. Growth of both organisms individually and their symbiotic root nodulation were investigated in liquid and hydroponic systems. While 23 and 18 mg l-1 of E171 and non-nanomaterial TiO2 decreased the growth rate of R. trifolii by 43 and 23% respectively, P25 did not cause effects. Shoot length of red clover decreased between 41 and 62% for all tested TiO2 NPs. In 21% of the TiO2 NP treated plants, no nodules were found. At high concentrations certain TiO2 NPs impaired R. trifolii as well as red clover growth and their symbiosis in the hydroponic systems.

Physical and rheological properties of Titanium Dioxide modified asphalt

NASA Astrophysics Data System (ADS)

Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Chong, Ai Ling; Haini, Rosli; Khatijah Abu Bakar, Siti

2018-03-01

Titanium Dioxide (TiO2) has been known as a useful photocatalytic material that is attributed to the several characteristics includes high photocatalytic activity compared with other metal oxide photocatalysts, compatible with traditional construction materials without changing any original performance. This study investigates the physical and rheological properties of modified asphalt with TiO2. Five samples of asphalt with different concentration of TiO2 were studied, namely asphalt 2%, 4%, 6% 8% and 10% TiO2. The tests includes are penetration, softening point, ductility, rotational viscosity and dynamic shear rheometer (DSR) test. From the results of this study, it is noted that addition of TiO2 has significant effect on the physical properties of asphalt. The viscosity tests revealed that asphalt 10% TiO2 has good workability among with reducing approximately 15°C compared to base asphalt. Based on the results from DSR measurements, asphalt 10% TiO2 has reduced temperature susceptibility and increase stiffness and elastic behaviour in comparison to base asphalt. As a result, TiO2 can be considered to be an additive to modify the properties of asphalt.

Abrasion properties of self-suspended hairy titanium dioxide nanomaterials

NASA Astrophysics Data System (ADS)

Zhang, Jiao-xia; Liu, Si; Yan, Chao; Wang, Xiao-jing; Wang, Lei; Yu, Ya-ming; Li, Shi-yun

2017-11-01

Considering the excellent solubility of pyrrolidone ring organic compounds, the synthesized N-(trimethoxysilyl) propyl- N-methyl-2-pyrrolidone chlorides was tethered onto titanium dioxide (TiO2) nanoparticles to improve dispersion of TiO2, and then polyethylene oxide (PEO) oligomer through ion exchange embraced the tethered TiO2 to obtain a novel self-suspended hairy TiO2 nanomaterials without any solvent. A variety of techniques were carried out to illustrate the structure and properties of the self-suspended hairy TiO2 nanomaterials. It was found that TiO2 nanoparticles embody monodispersity in the hybrid system though the "false reunion" phenomenon occurring due to nonpermanent weak physical cross-linking. Remarkably, self-suspended hairy TiO2 nanomaterials exhibit lower viscosity, facilitating maneuverable and outstanding antifriction and wear resistance properties, due to the synergistic lubricating effect between spontaneously forming lubricating film and nano-lubrication of TiO2 cores, overcoming the deficiency of both solid and liquid lubricants. This make them promising candidates for the micro-electromechanic/nano-electromechanic systems (MEMS/NEMS).

X-ray photoelectron spectroscopy characterization of composite TiO 2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

NASA Astrophysics Data System (ADS)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P. G.

2005-02-01

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO 2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO 2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO 2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO 2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO 2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO 2/PVDF ratios led to film instability. PVDF-TiO 2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO 2 and the role played by the PVDF film during the degradation process.

Efficiencies of Dye-Sensitized Solar Cells using Ferritin-Encapsulated Quantum Dots with Various Staining Methods

NASA Astrophysics Data System (ADS)

Perez, Luis

Dye-sensitized solar cells (DSSC) have the potential to replace traditional and cost-inefficient crystalline silicon or ruthenium solar cells. This can only be accomplished by optimizing DSSC's energy efficiency. One of the major components in a dye-sensitized solar cell is the porous layer of titanium dioxide. This layer is coated with a molecular dye that absorbs sunlight. The research conducted for this paper focuses on the different methods used to dye the porous TiO2 layer with ferritin-encapsulated quantum dots. Multiple anodes were dyed using a method known as SILAR which involves deposition through alternate immersion in two different solutions. The efficiencies of DSSCs with ferritin-encapsulated lead sulfide dye deposited using SILAR were subsequently compared against the efficiencies produced by cells using the traditional immersion method. It was concluded that both methods resulted in similar efficiencies (? .074%) however, the SILAR method dyed the TiO2 coating significantly faster than the immersion method. On a related note, our experiments concluded that conducting 2 SILAR cycles yields the highest possible efficiency for this particular binding method. National Science Foundation.

Effect of Liquid Feed-Stock Composition on the Morphology of Titanium Dioxide Films Deposited by Thermal Plasma Spray.

PubMed

Adán, C; Marugán, J; van Grieken, R; Chien, K; Pershin, L; Coyle, T; Mostaghimi, J

2015-09-01

Titanium dioxide coatings were deposited on the surface of titanium foils by Thermal Plasma Spray (TPS) process. Three different TiO2 coatings were prepared using the commercial TiO2-P25 nanopowder and titanium isopropoxide precursor solution as feed-stocks. Structure and morphology of the TiO2-P25 powder and the plasma sprayed coatings were analyzed by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption-desorption isotherms, UV-visible spectroscopy and Scanning Electron Microscopy (SEM). XRD and Raman results indicate that the TiO2 coatings were composed of an anatase/rutile mixture that is conditioned by the suspension composition used to be sprayed. Coatings prepared from TiO2-P25 nanoparticles in water suspension (NW-P25) and titanium isopropoxide solution suspension (NSP-P25) are incorporated into the coatings without phase transformation and their anatase/rutile ratio percentage remains very similar to the starting TiO2-P25 powder. On the contrary, when titanium isopropoxide solution is used for spraying (SP), the amount of rutile increases in the final TiO2 coating. SEM analysis also reveals different microstructure morphology, coating thickness, density and porosity of the three TiO2 films that depend significantly on the type of feed-stock employed. Interestingly, we have observed the role of titanium isopropoxide in the formation of more porous and cohesive layers of TiO2. The NSP-P25 coating, prepared with a mix of titanium isopropoxide solution based on TiO2 nanoparticles, presents higher deposition efficiencies and higher coating thickness than the film prepared with nanoparticles suspended in water (NW-P25) or with titanium isopropoxide solutions (SP). This is due to the precursor solution is acting as the cement between TiO2 nanoparticles, improving the cohesive strength of the coating. In sum, NSP-P25 and NW-P25 coatings display a good photocatalytic potential, based on their light absorption properties and mechanical stability. Band gap of the nanoparticulated coatings displays a light absorption at wavelengths below 379 and 399 nm for NW-P25 and NSP-P25 respectively. On the contrary, the SP coating, despite to present lower band-gap value, has bad cohesive properties with surface crackings that makes it mechanically unstable. Therefore, mixtures of P25 nanoparticles with titanium isopropoxide as feed-stock materials can produce promising photocatalytic coatings.

The layer boundary effect on multi-layer mesoporous TiO 2 film based dye sensitized solar cells

DOE PAGES

Xu, Feng; Zhu, Kai; Zhao, Yixin

2016-10-10

Multi-layer mesoporous TiO 2 prepared by screen printing is widely used for fabrication of high-efficiency dye-sensitized solar cells (DSSCs). Here, we compare the three types of ~10 um thick mesoporous TiO 2 films, which were screen printed as 1-, 2- and 4-layers using the same TiO 2 nanocrystal paste. The layer boundary of the multi-layer mesoporous TiO 2 films was observed in the cross-section SEM. The existence of a layer boundary could reduce the photoelectron diffusion length with the increase of layer number. However, the photoelectron diffusion lengths of the Z907 dye sensitized solar cells based on these different layeredmore » mesoporous TiO 2 films are all longer than the film thickness. Consequently, the photovoltaic performance seems to have little dependence on the layer number of the multi-layer TiO 2 based DSSCs.« less

The layer boundary effect on multi-layer mesoporous TiO 2 film based dye sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Feng; Zhu, Kai; Zhao, Yixin

Multi-layer mesoporous TiO 2 prepared by screen printing is widely used for fabrication of high-efficiency dye-sensitized solar cells (DSSCs). Here, we compare the three types of ~10 um thick mesoporous TiO 2 films, which were screen printed as 1-, 2- and 4-layers using the same TiO 2 nanocrystal paste. The layer boundary of the multi-layer mesoporous TiO 2 films was observed in the cross-section SEM. The existence of a layer boundary could reduce the photoelectron diffusion length with the increase of layer number. However, the photoelectron diffusion lengths of the Z907 dye sensitized solar cells based on these different layeredmore » mesoporous TiO 2 films are all longer than the film thickness. Consequently, the photovoltaic performance seems to have little dependence on the layer number of the multi-layer TiO 2 based DSSCs.« less

Effects of Material Properties on Sedimentation and Aggregation of Titanium Dioxide Nanoparticles of Anatase and Rutile in the Aqueous Phase

EPA Science Inventory

This study investigated the sedimentation and aggregation kinetics of titanium dioxide (TiO2) nanoparticles with varying material properties (i.e., crystallinity, morphology, and chemical compositions). Used in the study were various types of commercially available TiO2 nanoparti...

Effect of Treatment Media on the Agglomeration of Titanium Dioxide Nanoparticles: Impact on Genotoxicity, Cellular Interaction, and Cell Cycle

EPA Science Inventory

ABSTRACT The widespread use of titanium dioxide (TiO2) nanoparticles in consumer products increases the probability of exposure to humans and the environment. Although TiO2 nanoparticles have been shown to induce DNA damage (comet assay) and chromosome damage (micronucleus ass...

Gd, I-doped TiO2 thin films coated on solid waste material: synthesis, characterization, and photocatalytic activity under UV or visible light irradiation

NASA Astrophysics Data System (ADS)

Deng, Siwei; Yu, Jiang; Yang, Chun; Chang, Jiahua; Wang, Yizheng; Wang, Ping; Xie, Shiqian

2017-10-01

In this work, titanium dioxide thin films doped with different concentrations of gadolinium (Gd) and iodine (I) were synthesized using the sol-gel method and successfully coated on solid waste material (made in our lab) by dipping, resulting in the titanium dioxide thin-film-coated material (TiO2M). Then, the doped titanium dioxide thin films were characterized by X-ray diffraction (XRD), SEM, and UV-Vis spectroscopy; the optimum coating cycle was evaluated by removal rates of COD and ammonia nitrogen in raw wastewater and secondary effluent. Moreover, the photocatalytic activity was determined by degradation efficiency of methyl orange. The results showed that TiO2M had desirable reusability and the photocatalytic activity was attractive under ultraviolet light irradiation. Furthermore, it is found that the amount of dopant in TiO2 was a key parameter in increasing the photoactivity. 1% Gd-doped TiO2M exhibited the best photocatalytic activity for the degradation of methyl orange with the removal rate reaching 85.55%. The result was in good agreement with the observed smaller crystallite size and profitable crystal structure (anatase phase). Besides, the TiO2M (0.8% Gd-doped TiO2M, 1% Gd-doped TiO2M, 10% I-doped TiO2M, and 5% I-1% Gd-doped TiO2M) with desirable photocatalytic activity at ultraviolet light irradiation was selected for the visible light photocatalytic experiments with taking methyl orange as the target pollutants. The results showed that all of them exhibited the similar photocatalytic activity after 7 h of sunlight irradiation (around 90% removal effect). In general, this research developed a very effective and environmentally friendly photocatalyst for pollutant degradation.

Toxicity of nanotitanium dioxide (TiO2-NP) on human monocytes and their mitochondria.

PubMed

Ghanbary, Fatemeh; Seydi, Enaytollah; Naserzadeh, Parvaneh; Salimi, Ahmad

2018-03-01

The effect of nanotitanium dioxide (TiO 2 -NP) in human monocytes is still unknown. Therefore, an understanding of probable cytotoxicity of TiO 2 -NP on human monocytes and underlining the mechanisms involved is of significant interest. The aim of this study was to assess the cytotoxicity of TiO 2 -NP on human monocytes. Using biochemical and flow cytometry assessments, we demonstrated that addition of TiO 2 -NP at 10 μg/ml concentration to monocytes induced cytotoxicity following 12 h. The TiO 2 -NP-induced cytotoxicity on monocytes was associated with intracellular reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP) collapse, lysosomal membrane injury, lipid peroxidation, and depletion of glutathione. According to our results, TiO 2 -NP triggers oxidative stress and organelles damages in monocytes which are important cells in defense against foreign agents. Finally, our findings suggest that use of antioxidants and mitochondrial/lysosomal protective agents could be of benefit for the people in the exposure with TiO 2 -NP.

QCM gas sensor characterization of ALD-grown very thin TiO2 films

NASA Astrophysics Data System (ADS)

Boyadjiev, S.; Georgieva, V.; Vergov, L.; Szilágyi, I. M.

2018-03-01

The paper presents a technology for preparation and characterization of titanium dioxide (TiO2) thin films suitable for gas sensor applications. Applying atomic layer deposition (ALD), very thin TiO2 films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The TiO2 thin films were grown using Ti(iOPr)4 and water as precursors. The surface of the films was observed by scanning electron microscopy (SEM), coupled with energy dispersive X-ray analysis (EDX) used for a composition study. The research was focused on the gas-sensing properties of the films. Films of 10-nm thickness were deposited on quartz resonators with Au electrodes and the QCMs were used to build highly sensitive gas sensors, which were tested for detecting NO2. Although very thin, these ALD-grown TiO2 films were sensitive to NO2 already at room temperature and could register as low concentrations as 50 ppm, while the sorption was fully reversible, and the sensors could be fully recovered. With the technology presented, the manufacturing of gas sensors is simple, fast and cost-effective, and suitable for energy-effective portable equipment for real-time environmental monitoring of NO2.

Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings

PubMed Central

Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Kanehira, Minoru

2013-01-01

Vanadium dioxide (VO2) is a Mott phase transition compound that can be applied as a thermochromic smart material for energy saving and comfort, and titanium dioxide (TiO2) is a well-known photocatalyst for self-cleaning coatings. In this paper, we report a VO2@TiO2 core-shell structure, in which the VO2 nanorod core exhibits a remarkable modulation ability for solar infrared light, and the TiO2 anatase shell exhibits significant photocatalytic degradation of organic dye. In addition, the TiO2 overcoating not only increased the luminous transmittance of VO2 based on an antireflection effect, but also modified the intrinsic colour of VO2 films from yellow to light blue. The TiO2 also enhanced the chemical stability of VO2 against oxidation. This is the first report of such a single nanoparticle structure with both thermochromic and photocatalytic properties that offer significant potential for creating a multifunctional smart coating. PMID:23546301

Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings.

PubMed

Li, Yamei; Ji, Shidong; Gao, Yanfeng; Luo, Hongjie; Kanehira, Minoru

2013-01-01

Vanadium dioxide (VO2) is a Mott phase transition compound that can be applied as a thermochromic smart material for energy saving and comfort, and titanium dioxide (TiO2) is a well-known photocatalyst for self-cleaning coatings. In this paper, we report a VO2@TiO2 core-shell structure, in which the VO2 nanorod core exhibits a remarkable modulation ability for solar infrared light, and the TiO2 anatase shell exhibits significant photocatalytic degradation of organic dye. In addition, the TiO2 overcoating not only increased the luminous transmittance of VO2 based on an antireflection effect, but also modified the intrinsic colour of VO2 films from yellow to light blue. The TiO2 also enhanced the chemical stability of VO2 against oxidation. This is the first report of such a single nanoparticle structure with both thermochromic and photocatalytic properties that offer significant potential for creating a multifunctional smart coating.

Modified surface of titanium dioxide nanoparticles-based biosensor for DNA detection

NASA Astrophysics Data System (ADS)

Nadzirah, Sh.; Hashim, U.; Rusop, M.

2018-05-01

A new technique was used to develop a simple and selective picoammeter DNA biosensor for identification of E. coli O157:H7. This biosensor was fabricated from titanium dioxide nanoparticles that was synthesized by sol-gel method and spin-coated on silicon dioxide substrate via spinner. 3-Aminopropyl triethoxy silane (APTES) was used to modify the surface of TiO2. Simple surface modification approach has been applied; which is single dropping of APTES onto the TiO2 nanoparticles surface. Carboxyl modified probe DNA has been bind onto the surface of APTES/TiO2 without any amplifier element. Electrical signal has been used as the indicator to differentiate each step (surface modification of TiO2 and probe DNA immobilization). The I-V measurements indicate extremely low current (pico-ampere) flow through the device which is 2.8138E-10 A for pure TiO2 nanoparticles, 2.8124E-10 A after APTES modification and 3.5949E-10 A after probe DNA immobilization.

Design of flexible PANI-coated CuO-TiO2-SiO2 heterostructure nanofibers with high ammonia sensing response values

NASA Astrophysics Data System (ADS)

Pang, Zengyuan; Nie, Qingxin; Lv, Pengfei; Yu, Jian; Huang, Fenglin; Wei, Qufu

2017-06-01

We report a room-temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI)-coated titanium dioxide-silicon dioxide (TiO2-SiO2) or copper oxide-titanium dioxide-silicon dioxide (CuO-TiO2-SiO2) composite nanofibers. Such flexible inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers were prepared by electrospinning, followed by calcination. Then, in situ polymerization of aniline monomers was carried out with inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers as templates. Gas sensing tests at room temperature indicated that the obtained CuO-TiO2-SiO2/PANI composite nanofibers had much higher response values to ammonia gas (ca. 45.67-100 ppm) than most of those reported before as well as the prepared TiO2-SiO2/PANI composite nanofibers here. These excellent sensing properties may be due to the P-N, P-P heterojunctions and a structure similar to field-effect transistors formed on the interfaces between PANI, TiO2, and CuO, which is p-type, n-type, and p-type semiconductor, respectively. In addition, the prepared free-standing CuO-TiO2-SiO2/PANI composite nanofiber membrane was easy to handle and possessed ideal flexibility, which is promising for potential applications in wearable sensors in the future.

Design of flexible PANI-coated CuO-TiO2-SiO2 heterostructure nanofibers with high ammonia sensing response values.

PubMed

Pang, Zengyuan; Nie, Qingxin; Lv, Pengfei; Yu, Jian; Huang, Fenglin; Wei, Qufu

2017-06-02

We report a room-temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI)-coated titanium dioxide-silicon dioxide (TiO 2 -SiO 2 ) or copper oxide-titanium dioxide-silicon dioxide (CuO-TiO 2 -SiO 2 ) composite nanofibers. Such flexible inorganic TiO 2 -SiO 2 and CuO-TiO 2 -SiO 2 composite nanofibers were prepared by electrospinning, followed by calcination. Then, in situ polymerization of aniline monomers was carried out with inorganic TiO 2 -SiO 2 and CuO-TiO 2 -SiO 2 composite nanofibers as templates. Gas sensing tests at room temperature indicated that the obtained CuO-TiO 2 -SiO 2 /PANI composite nanofibers had much higher response values to ammonia gas (ca. 45.67-100 ppm) than most of those reported before as well as the prepared TiO 2 -SiO 2 /PANI composite nanofibers here. These excellent sensing properties may be due to the P-N, P-P heterojunctions and a structure similar to field-effect transistors formed on the interfaces between PANI, TiO 2 , and CuO, which is p-type, n-type, and p-type semiconductor, respectively. In addition, the prepared free-standing CuO-TiO 2 -SiO 2 /PANI composite nanofiber membrane was easy to handle and possessed ideal flexibility, which is promising for potential applications in wearable sensors in the future.

Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light.

PubMed

Tanabe, Ichiro; Kurawaki, Yuji

2018-05-15

Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤200nm) region of titanium dioxide (TiO 2 ) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO 2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO 2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO 2 under visible light, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

TiO2 surface functionalization of COC based planar waveguide Bragg gratings for refractive index sensing

NASA Astrophysics Data System (ADS)

Rosenberger, M.; Girschikofsky, M.; Förthner, M.; Belle, S.; Rommel, M.; Frey, L.; Schmauss, B.; Hellmann, R.

2018-01-01

We demonstrate the applicability of a planar waveguide Bragg grating in cyclo-olefin copolymer (COC) for refractive index sensing. The polymer planar waveguide Bragg grating fabricated using a single writing step technique is coated with a high-index layer of titanium dioxide (TiO2) leading to a distinct birefringence. This in turn results in the splitting of the Bragg reflection into two distinct Bragg wavelengths, which strongly differ regarding their refractive index sensitivities. Where one wavelength is only slightly affected by the ambient refractive index, the second Bragg peak shows a strong sensitivity. Furthermore, we investigate the temperature behaviour of the functionalized sensor and discuss it with respect to applications in refractive index sensing.

Biophysical mechanisms of modification of skin optical properties in the UV wavelength range with nanoparticles

NASA Astrophysics Data System (ADS)

Popov, A. P.; Priezzhev, A. V.; Lademann, J.; Myllylä, R.

2009-05-01

In this paper, by means of the Mie theory and Monte Carlo simulations we investigate modification of optical properties of the superficial layer of human skin (stratum corneum) for 310- and 400-nm ultraviolet (UV) radiation by embedding of 35-200-nm-sized particles of titanium dioxide (TiO2) and silicon (Si). Problem of skin protection against UV light is of major importance due to increased frequency of skin cancer provoked by excessive doses of accepted UV radiation. For 310-nm light, the optimal sizes of the TiO2 and Si particles are found to be 62 and 55 nm, respectively, and for 400-nm radiation, 122 and 70 nm, respectively.

Dye sensitized solar cell based on environmental friendly eosin Y dye and Al doped titanium dioxide nano particles

NASA Astrophysics Data System (ADS)

Kulkarni, Swati S.; Bodkhe, Gajanan A.; Shirsat, Sumedh M.; Hussaini, S. S.; Shejwal, N. N.; Shirsat, Mahendra D.

2018-03-01

Present communication deals with the development of cost effective dye sensitized solar cell (DSSC) with eco-friendly materials. Eco-friendly Eosin Y dye was used to sensitize photo anode which was fabricated using undoped and Aluminium doped titanium dioxide (TiO2) nanoparticles. Undoped and Aluminium doped TiO2 nanoparticles were synthesized by simple and cost effective sol-gel method. Aluminium doped and undoped TiO2 nanoparticles were characterized using UV-visible, FT-IR spectroscopy, x-ray Diffraction, and Scanning Electron Micrograph with EDX. The photo-voltaic activity of the cell was studied under light irradiation of 100 milliwatt cm-2. Aluminium doped TiO2 nanoparticle photo electrode exhibits more than 60% increase in cell efficiency as compared to the undoped TiO2 nanoparticle photo electrode.

Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

NASA Astrophysics Data System (ADS)

Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

2018-02-01

Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

Optical, electrical and dielectric properties of TiO2-SiO2 films prepared by a cost effective sol-gel process.

PubMed

Vishwas, M; Rao, K Narasimha; Gowda, K V Arjuna; Chakradhar, R P S

2011-12-01

Titanium dioxide (TiO(2)) and silicon dioxide (SiO(2)) thin films and their mixed films were synthesized by the sol-gel spin coating method using titanium tetra isopropoxide (TTIP) and tetra ethyl ortho silicate (TEOS) as the precursor materials for TiO(2) and SiO(2) respectively. The pure and composite films of TiO(2) and SiO(2) were deposited on glass and silicon substrates. The optical properties were studied for different compositions of TiO(2) and SiO(2) sols and the refractive index and optical band gap energies were estimated. MOS capacitors were fabricated using TiO(2) films on p-silicon (100) substrates. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics were studied and the electrical resistivity and dielectric constant were estimated for the films annealed at 200°C for their possible use in optoelectronic applications. Copyright © 2011 Elsevier B.V. All rights reserved.

Studies on optical and electrical properties of green synthesized TiO2@Ag core-shell nanocomposite material

NASA Astrophysics Data System (ADS)

Ganapathy, M.; Senthilkumar, N.; Vimalan, M.; Jeysekaran, R.; Vetha Potheher, I.

2018-04-01

Newly adopted green approach has been used to synthesize pure titanium dioxide (TiO2) nanoparticles (NPs) and silver deposited titanium dioxide (TiO2@Ag) core–shell nanocomposite (CSNC) from Nigella Sativa (black cumin) seed extract for the first time. The phytochemicals available in Nigella Sativa (NS) seed extract acts as reducing agent in the formation of nanoparticles as well as nanocomposite. The morphology, crystal structure, particle size and phase composition of green synthesized TiO2 NPs and TiO2@Ag CSNC are investigated by High Resolution Transmission Electron Microscopy (HRTEM), Field Emission Scanning Electron Microscopy (FESEM), Powder x-ray diffraction (PXRD), FT–Raman and Fourier Transform Infrared spectroscopy (FT-IR). The red shift in (from 333 nm to 342 nm) UV–Vis spectrum confirmed the deposition of Ag on TiO2. The reduced intensity peaks of Photoluminescence spectra (PL) also indicate the deposition of Ag on TiO2. Further the electrical properties of pure TiO2 and TiO2@Ag CSNC have studied by dielectric studies and ac conductivity measurements. The dielectric constant and the dielectric loss of TiO2@Ag CSNC are better than pure TiO2. From these improved results, the green synthesized TiO2@Ag CSNC from NS seed extract is may be a suitable material for device fabrication in the visible region.

Nano-Scaled Particles of Titanium Dioxide Convert Benign Mouse Fibrosarcoma Cells into Aggressive Tumor Cells

PubMed Central

Onuma, Kunishige; Sato, Yu; Ogawara, Satomi; Shirasawa, Nobuyuki; Kobayashi, Masanobu; Yoshitake, Jun; Yoshimura, Tetsuhiko; Iigo, Masaaki; Fujii, Junichi; Okada, Futoshi

2009-01-01

Nanoparticles are prevalent in both commercial and medicinal products; however, the contribution of nanomaterials to carcinogenesis remains unclear. We therefore examined the effects of nano-sized titanium dioxide (TiO2) on poorly tumorigenic and nonmetastatic QR-32 fibrosarcoma cells. We found that mice that were cotransplanted subcutaneously with QR-32 cells and nano-sized TiO2, either uncoated (TiO2−1, hydrophilic) or coated with stearic acid (TiO2−2, hydrophobic), did not form tumors. However, QR-32 cells became tumorigenic after injection into sites previously implanted with TiO2−1, but not TiO2−2, and these developing tumors acquired metastatic phenotypes. No differences were observed either histologically or in inflammatory cytokine mRNA expression between TiO2−1 and TiO2−2 treatments. However, TiO2−2, but not TiO2−1, generated high levels of reactive oxygen species (ROS) in cell-free conditions. Although both TiO2−1 and TiO2−2 resulted in intracellular ROS formation, TiO2−2 elicited a stronger response, resulting in cytotoxicity to the QR-32 cells. Moreover, TiO2−2, but not TiO2−1, led to the development of nuclear interstices and multinucleate cells. Cells that survived the TiO2 toxicity acquired a tumorigenic phenotype. TiO2-induced ROS formation and its related cell injury were inhibited by the addition of antioxidant N-acetyl-l-cysteine. These results indicate that nano-sized TiO2 has the potential to convert benign tumor cells into malignant ones through the generation of ROS in the target cells. PMID:19815711

Microstructure and antibacterial property of in situ TiO(2) nanotube layers/titanium biocomposites.

PubMed

Cui, C X; Gao, X; Qi, Y M; Liu, S J; Sun, J B

2012-04-01

The TiO(2) nanotube layer was in situ synthesized on the surface of pure titanium by the electrochemical anodic oxidation. The diameter of nano- TiO(2) nanotubes was about 70~100 nm. The surface morphology and phase compositions of TiO(2) nanotube layers were observed and analyzed using the scanning electron microscope (SEM). The important processing parameters, including anodizing voltage, reaction time, concentration of electrolyte, were optimized in more detail. The photocatalytic activity of the nano- TiO(2) nanotube layers prepared with optimal conditions was evaluated via the photodegradation of methylthionine in aqueous solution. The antibacterial property of TiO(2) nanotube layers prepared with optimal conditions was evaluated by inoculating Streptococcus mutans on the TiO(2) nanotube layers in vitro. The results showed that TiO(2) nanotube layers/Ti biocomposites had very good antibacterial activity to resist Streptococcus mutans. As a dental implant biomaterial, in situ TiO(2) nanotube layer/Ti biocomposite has better and wider application prospects. Copyright © 2012 Elsevier Ltd. All rights reserved.

Improvement in electrical characteristics of eco-friendly indium zinc oxide thin-film transistors by photocatalytic reaction.

PubMed

Kang, Jun Ki; Park, Sung Pyo; Na, Jae Won; Lee, Jin Hyeok; Kim, Dongwoo; Kim, Hyun Jae

2018-05-11

Eco-friendly solution-processed oxide thin-film transistors (TFTs) were fabricated through photocatalytic reaction of titanium dioxide (PRT). The titanium dioxide (TiO 2 ) surface reacts with H 2 O under ultraviolet (UV) light irradiation and generates hydroxyl radicals (OH∙). These hydroxyl radicals accelerate the decomposition of large organic compounds such as 2-methoxyethanol (2ME; one of the representative solvents for solution-processed metal oxides), creating smaller organic molecular structures compared with 2ME. The decomposed small organic materials have low molar masses and low boiling points, which help improving electrical properties via diminishing defect sites in oxide channel layers and fabricating low temperature solution-processed oxide TFTs. As a result, the field-effect mobility improved from 4.29 to 10.24 cm 2 /V·s for IGZO TFTs and from 2.78 to 7.82 cm 2 /V·s for IZO TFTs, and the V th shift caused by positive bias stress (PBS) and negative bias illumination stress (NBIS) over 1,000 s under 5,700 lux decreased from 6.2 to 2.9 V and from 15.3 to 2.8 V, respectively. In theory, TiO 2 has a permanent photocatalytic reaction; as such, hydroxyl radicals are generated continuously under UV irradiation, improving the electrical characteristics of solution-processed IZO TFTs even after four iterations of TiO 2 recycling in this study. Thus, the PRT method provides an eco-friendly approach for high-performance solution-processed oxide TFTs.

Dual functional reduced graphene oxide as photoanode and counter electrode in dye-sensitized solar cells and its exceptional efficiency enhancement

NASA Astrophysics Data System (ADS)

Jumeri, F. A.; Lim, H. N.; Zainal, Z.; Huang, N. M.; Pandikumar, A.; Lim, S. P.

2015-10-01

The dual functionalities of reduced graphene oxide (rGO) as photoanode and counter electrode in dye-sensitized solar cells (DSSCs) is explored. A titanium dioxide (TiO2) film is deposited on an indium tin oxide (ITO) glass using an in-house aerosol-assisted chemical vapor deposition method. Graphene oxide (GO) is then introduced onto the TiO2-ITO substrate, and the GO layer is successively thermally treated to rGO. The TiO2-rGO film is used as a compact layer for the photoanode of the DSSC. A layer of zinc oxide-silver (ZnO-Ag) is introduced on top of the compact layer as an active material. Its highly porous flower-shaped morphology is advantageous for the adsorption of dye. The in-situ electrochemical polymerization method used for the fabrication of polypyrrole incorporated with rGO and p-toluenesulfonate (pTS) (Ppy-rGO-pTS) on an ITO glass is used as a counter electrode for the DSSC. The DSSC assembled with the Ppy-rGO-1.0pTS counter electrode exhibites an enhanced conversion efficiency of 1.99% under solar illumination, which is better than that using conventional Pt as a counter electrode (0.08%). This is attributed to the increased contact area between the Ppy-rGO-pTS counter electrode and electrolyte, which subsequently improves the conductivity and high electrocatalytic activities of the Ppy-rGO-pTS counter electrode.

Cobalt and Yttrium Modified TiO2 Nanotubes Based Dye-Sensitized Solar Cells for Solar-Energy Conversion

NASA Astrophysics Data System (ADS)

Shabanov, N. S.; Isaev, A. B.; Orudzhev, F. F.; Murliev, E. K.

2018-01-01

The solar-energy conversion in eosin-sensitized solar cells based on cobalt and yttrium modified TiO2 nanotubes has been studied.It is established that the doping with metal ions shifts the absorption edge for Co and Y doped titanium dioxide samples to longer and shorter wavelengths, respectively. The efficiency of solar energy conversion depends on the wide bandgap of the semiconductor anode and reaches a maximum (4.4%) for yttrium-doped TiO2 in comparison to that (4.1%) for pure titanium dioxide.

Product selectivity of visible-light photocatalytic reduction of carbon dioxide using titanium dioxide doped by different nitrogen-sources

NASA Astrophysics Data System (ADS)

Zhang, Zhaoguo; Huang, Zhengfeng; Cheng, Xudong; Wang, Qingli; Chen, Yi; Dong, Peimei; Zhang, Xiwen

2015-11-01

The influence of nitrogen-source on the photocatalytic properties of nitrogen-doped titanium dioxide is herein first investigated from the perspective of the chemical bond form of the nitrogen element in the nitrogen-source. The definitive role of groups such as Nsbnd N from the nitrogen-source on the surface of as-prepared samples in the selectivity of the dominant product of photocatalytic reduction is demonstrated. Well-crystallized one-dimensional Nsbnd TiO2 nanorod arrays with a preferred orientation of the rutile (3 1 0) facet are manufactured via a hydrothermal treatment using hydrazine and ammonia variously as the source of nitrogen. Significant selectivity of the dominant reduced products has been exhibited for Nsbnd TiO2 prepared from different nitrogen-sources in carbon dioxide photocatalytic reduction under visible light illumination. CH4 is the main product with N2H4-doped Nsbnd TiO2, while CO is the main product with NH3-doped Nsbnd TiO2, which can be attributed to the existence of the reducing Nsbnd N groups in the N2H4-doped Nsbnd TiO2 surfaces after the hydrothermal treatment. Compared with the approaches previously reported, the facile one-step route utilized here accomplishes the fabrication of Nsbnd TiO2 possessing visible-light activity and attainment of selectivity of dominant photocatalytic reduction product simultaneously by choosing a nitrogen-source with appropriate chemical bond form, which provides a completely new approach to understanding the effects of doping treatment on photocatalytic properties.

Surface force analysis of glycine adsorption on different crystal surfaces of titanium dioxide (TiO2).

PubMed

Ganbaatar, Narangerel; Imai, Kanae; Yano, Taka-Aki; Hara, Masahiko

2017-01-01

Surface force analysis with atomic force microscope (AFM) in which a single amino acid residue was mounted on the tip apex of AFM probe was carried out for the first time at the molecular level on titanium dioxide (TiO 2 ) as a representative mineral surface for prebiotic chemical evolution reactions. The force analyses on surfaces with three different crystal orientations revealed that the TiO 2 (110) surface has unique characteristics for adsorbing glycine molecules showing different features compared to those on TiO 2 (001) and (100). To examine this difference, we investigated thermal desorption spectroscopy (TDS) and the interaction between the PEG cross-linker and the three TiO 2 surfaces. Our data suggest that the different single crystal surfaces would provide different chemical evolution field for amino acid molecules.

Effect of Coating and Packaging Materials on Photocatalytic and Antimicrobial Activities of Titanium Dioxide Nanoparticles

USDA-ARS?s Scientific Manuscript database

Food safety or foodborne pathogen contamination is a major concern in food industry. Titanium dioxide (TiO2) is a photocatalyst and can inactivate a wide spectrum of microorganisms under UV illumination. There is significant interest in the development of TiO2-coated or –incorporated food packaging ...

Titanium dioxide nanoparticles: some aspects of toxicity/focus on the development.

PubMed

Rollerova, E; Tulinska, J; Liskova, A; Kuricova, M; Kovriznych, J; Mlynarcikova, A; Kiss, A; Scsukova, S

2015-04-01

Nanosized titanium dioxide (TiO2) particles belong to the most widely manufactured nanoparticles (NPs) on a global scale because of their photocatalytic properties and the related surface effects. TiO2 NPs are in the top five NPs used in consumer products. Ultrafine TiO2 is widely used in the number of applications, including white pigment in paint, ceramics, food additive, food packaging material, sunscreens, cosmetic creams, and, component of surgical implants. Data evidencing rapid distribution, slow or ineffective elimination, and potential long-time tissue accumulation are especially important for the human risk assessment of ultrafine TiO2 and represent new challenges to more responsibly investigate potential adverse effects by the action of TiO2 NPs considering their ubiquitous exposure in various doses. Transport of ultrafine TiO2 particles in systemic circulation and further transition through barriers, especially the placental and blood-brain ones, are well documented. Therefore, from the developmental point of view, there is a raising concern in the exposure to TiO2 NPs during critical windows, in the pregnancy or the lactation period, and the fact that human mothers, women and men in fertile age and last but not least children may be exposed to high cumulative doses. In this review, toxicokinetics and particularly toxicity of TiO2 NPs in relation to the developing processes, oriented mainly on the development of the central nervous system, are discussed Keywords: nanoparticles, nanotoxicity, nanomaterials, titanium dioxide, reproductive toxicity, developmental toxicity, blood brain barrier, placental barrier.

Synthesis of nanostructured titanium dioxide layer onto kaolin hollow fibre membrane via hydrothermal method for decolourisation of reactive black 5.

PubMed

Mohtor, Nur Hamizah; Othman, Mohd Hafiz Dzarfan; Bakar, Suriani Abu; Kurniawan, Tonni Agustiono; Dzinun, Hazlini; Norddin, Muhammad Noorul Anam Mohd; Rajis, Zanariah

2018-05-28

Hydrothermal method has been proven to be an effective method to synthesise the nanostructured titanium dioxide (TiO 2 ) with good morphology and uniform distribution at low temperature. Despite of employing a well-known and commonly used glass substrate as the support to hydrothermally synthesise the nanostructured TiO 2 , this study emphasised on the application of kaolin hollow fibre membrane as the support for the fabrication of kaolin/TiO 2 nanorods (TNR) membrane. By varying the hydrothermal reaction times (2 h, 6 h, and 10 h), the different morphology, distribution, and properties of TiO 2 nanorods on kaolin support were observed by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). It was found that the well-dispersed of TiO 2 nanorods have improved the surface affinity of kaolin/TNR membrane towards water, allowing kaolin/TNR membrane prepared from 10 h of hydrothermal reaction to exhibit the highest water permeation of 165 L/h.m 2 .bar. In addition, this prepared membrane also showed the highest photocatalytic activity of 80.3% in the decolourisation of reactive black 5 (RB5) under UV irradiation. On top of that, the kaolin/TNR membrane prepared from 10 h of hydrothermal reaction also exhibited a good resistance towards photocorrosion, enabling the reuse of this membrane for three consecutive cycles of photocatalytic degradation of RB5 without showing significant reduction in photocatalytic efficiency towards the decolourisation of RB5. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of Titanium Dioxide Nanoparticles on Red Clover and Its Rhizobial Symbiont

PubMed Central

Moll, Janine; Okupnik, Annette; Gogos, Alexander; Knauer, Katja; Bucheli, Thomas D.; van der Heijden, Marcel G. A.; Widmer, Franco

2016-01-01

Titanium dioxide nanoparticles (TiO2 NPs) are in consideration to be used in plant protection products. Before these products can be placed on the market, ecotoxicological tests have to be performed. In this study, the nitrogen fixing bacterium Rhizobium trifolii and red clover were exposed to two TiO2 NPs, i.e., P25, E171 and a non-nanomaterial TiO2. Growth of both organisms individually and their symbiotic root nodulation were investigated in liquid and hydroponic systems. While 23 and 18 mg l-1 of E171 and non-nanomaterial TiO2 decreased the growth rate of R. trifolii by 43 and 23% respectively, P25 did not cause effects. Shoot length of red clover decreased between 41 and 62% for all tested TiO2 NPs. In 21% of the TiO2 NP treated plants, no nodules were found. At high concentrations certain TiO2 NPs impaired R. trifolii as well as red clover growth and their symbiosis in the hydroponic systems. PMID:27171465

Two steps hydrothermal growth and characterisations of BaTiO3 films composed of nanowires

NASA Astrophysics Data System (ADS)

Zawawi, Che Zaheerah Najeehah Che Mohd; Salleh, Shahril; Oon Jew, Lee; Tufail Chaudhary, Kashif; Helmi, Mohamad; Safwan Aziz, Muhammad; Haider, Zuhaib; Ali, Jalil

2018-05-01

Barium titanate (BaTiO3) films composed of nanowires have gained considerable research interest due to their lead-free composition and strong energy conversion efficiency. BaTiO3 films can be developed with a simple two steps hydrothermal reactions, which are low cost effective. In this research, BaTiO3 films were fabricated on titanium foil through two steps hydrothermal method namely, the growth of TiO2 and followed by BaTiO3 films. The structural evolutions and the dielectric properties of the films were investigated as well. The structural evolutions of titanium dioxide (TiO2) and BaTiO3 nanowires were characterized using X-ray diffraction and scanning electron microscopy. First step of hydrothermal reaction, TiO2 nanowires were prepared in varied temperatures of 160 °C, 200 °C and 250 °C respectively. Second step of hydrothermal reaction was performed to produce a layer of BaTiO3 films.

Engineering the Surface/Interface Structures of Titanium Dioxide Micro and Nano Architectures towards Environmental and Electrochemical Applications

PubMed Central

Wang, Xiaoliang; Zhao, Yanyan; Mølhave, Kristian

2017-01-01

Titanium dioxide (TiO2) materials have been intensively studied in the past years because of many varied applications. This mini review article focuses on TiO2 micro and nano architectures with the prevalent crystal structures (anatase, rutile, brookite, and TiO2(B)), and summarizes the major advances in the surface and interface engineering and applications in environmental and electrochemical applications. We analyze the advantages of surface/interface engineered TiO2 micro and nano structures, and present the principles and growth mechanisms of TiO2 nanostructures via different strategies, with an emphasis on rational control of the surface and interface structures. We further discuss the applications of TiO2 micro and nano architectures in photocatalysis, lithium/sodium ion batteries, and Li–S batteries. Throughout the discussion, the relationship between the device performance and the surface/interface structures of TiO2 micro and nano structures will be highlighted. Then, we discuss the phase transitions of TiO2 nanostructures and possible strategies of improving the phase stability. The review concludes with a perspective on the current challenges and future research directions. PMID:29120393

Oxygen-implanted induced formation of oxide layer enhances blood compatibility on titanium for biomedical applications.

PubMed

Hung, Wei-Chiang; Chang, Fang-Mo; Yang, Tzu-Sen; Ou, Keng-Liang; Lin, Che-Tong; Peng, Pei-Wen

2016-11-01

Titanium dioxide (TiO2) layers were prepared on a Ti substrate by using oxygen plasma immersion ion implantation (oxygen PIII). The surface chemical states, structure, and morphology of the layers were studied using X-ray photoelectron spectroscopy, X-ray diffraction, Raman microscopy, atomic force microscopy and scanning electron microscope. The mechanical properties, such as the Young's modulus and hardness, of the layers were investigated using nanoindentation testing. The Ti(4+) chemical state was determined to be present on oxygen-PIII-treated surfaces, which consisted of nanocrystalline TiO2 with a rutile structure. Compared with Ti substrates, the oxygen-PIII-treated surfaces exhibited decreased Young's moduli and hardness. Parameters indicating the blood compatibility of the oxygen-PIII-treated surfaces, including the clotting time and platelet adhesion and activation, were studied in vitro. Clotting time assays indicated that the clotting time of oxygen-PIII-treated surfaces was longer than that of the Ti substrate, which was associated with decreased fibrinogen adsorption. In conclusion, the surface characteristics and the blood compatibility of Ti implants can be modified and improved using oxygen PIII. Copyright © 2016 Elsevier B.V. All rights reserved.

Dynamic quenching study of 2-amino-3-bromo-1,4-naphthoquinone by titanium dioxide nano particles in solution (methanol).

PubMed

Pushpam, S; Kottaisamy, M; Ramakrishnan, V

2013-10-01

The dependence of fluorescence emission of 2-amino-3-bromo-1,4-naphthoquinone on titanium dioxide (TiO2) in methanol has been investigated. The increase in TiO2 concentration causes a decrease in the fluorescence intensity of 2-amino-3-bromo-1,4-naphthoquinone. A linear Stern-Volmer plot in this study indicates the presence of dynamic quenching. The quenching and association constants have been calculated. The quenching process is due to the electron transfer from 2-amino-3-bromo-1,4-naphthoquinone to TiO2. Copyright © 2013 Elsevier B.V. All rights reserved.

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application

PubMed Central

Dalapati, Goutam Kumar; Masudy-Panah, Saeid; Chua, Sing Teng; Sharma, Mohit; Wong, Ten It; Tan, Hui Ru; Chi, Dongzhi

2016-01-01

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry. PMID:26846687

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application.

PubMed

Dalapati, Goutam Kumar; Masudy-Panah, Saeid; Chua, Sing Teng; Sharma, Mohit; Wong, Ten It; Tan, Hui Ru; Chi, Dongzhi

2016-02-05

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry.

New insight into the disinfection mechanism of Fusarium monoliforme and Aspergillus niger by TiO2 photocatalyst under low intensity UVA light.

PubMed

Pokhum, Chonlada; Viboonratanasri, Duangamon; Chawengkijwanich, Chamorn

2017-11-01

Titanium dioxide (TiO 2) photocatalytic reaction has great potential for the disinfection of harmful pathogens. However, the disinfection mechanisms of TiO 2 photocatalysis are not yet well-known for fungi and protozoa. In this work, the photocatalytic disinfection mechanism of Fusarium monoliforme and Aspergillus niger under low intensity UVA light (365nm, <10W/m 2 ) was studied at the ultrastructural level. Photocatalytic treatments showed that the photocatalytic oxidation of 10% TiO 2 based paint was efficacious in the complete disinfection of F. monoliforme under low intensity UVA light. No growth of F. monoliforme was observed on agar plate in the subsequent dark. Transmission electron microscopy (TEM) of F. monoliforme exposed to TiO 2 photocatalysis treatment showed a distinct damage to electron-dense outer cell wall, but not to an underlying electron-transparent layer cell wall. The TEM image revealed that the UVA-light only did not damage cell wall, cell membrane and cellular organelles. Unlike, A. niger was more sensitive to UVA-light. Serious destructions of cell membrane and cellular organelles were shown in A. niger exposed to UVA-light only and photocatalytic treatments. However, morphological change in A. niger cell wall was only observed in photocatalytic treatment. Changes to the outermost melanin like layer and cell wall of A. niger spore due to photocatalytic treatment were greatly apparent while the intracellular organelles of A. niger spore were not affected. Therefore, regrowth of A. niger on agar plate was expected from the germination of A. niger spore in the subsequent dark. These observations give a better understanding of the photocatalytic disinfection mechanism toward fungi. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of oral administration of titanium dioxide fine-sized particles on plasma glucose in mice.

PubMed

Gu, Ning; Hu, Hailong; Guo, Qian; Jin, Sanli; Wang, Changlin; Oh, Yuri; Feng, Yujie; Wu, Qiong

2015-12-01

Titanium dioxide (TiO2) is an authorized additive used as a food colorant, is composed of nano-sized particles (NP) and fine-sized particles (FP). Previous study reported that oral administration of TiO2 NPs triggers an increase in plasma glucose of mice. However, no previous studies have focused on toxic effects of TiO2 FPs on plasma glucose homeostasis following oral administration. In the current study, mice were orally administered TiO2 FPs greater than 100 nm in size (64 mg/kg body weight per day), and effects on plasma glucose levels examined. Our results showed that titanium levels was not changed in mouse blood, livers and pancreases after mice were orally administered TiO2 FPs. Biochemical analyzes showed that plasma glucose and ROS levels were not affected by TiO2 FPs. Histopathological results showed that TiO2 FPs did not induce pathology changes in organs, especially plasma glucose homeostasis regulation organs, such as pancreas and liver. Western blotting showed that oral administration of TiO2 FPs did not induce insulin resistance (IR) in mouse liver. These results showed that, TiO2 FPs cannot be absorbed via oral administration and affect plasma glucose levels in mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

Deposition of gold nanoparticles from colloid on TiO2 surface

NASA Astrophysics Data System (ADS)

Rehacek, Vlastimil; Hotovy, Ivan

2017-11-01

In this paper, experimental results are presented on the deposition of colloidal gold nanoparticles on the surfaces of TiO2 prepared on silicon/silicon dioxide. Important procedures, such as titanium dioxide surface hydrophilization as well as functionalization by an organosilane coupling agent (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane were investigated in order to obtain a metal oxide surface with the most convenient properties for immobilization of gold nanoparticles having a dense and uniform distribution. TiO2 nanotips prepared by reactive ion etching of oxide surface covered with self-mask gold nanoparticles are demonstrated.

Pulsed photoinitiated fabrication of inkjet printed titanium dioxide/reduced graphene oxide nanocomposite thin films.

PubMed

Bourgeois, Briley; Luo, Sijun; Riggs, Brian; Ji, Yaping; Adireddy, Shiva; Schroder, Kurt; Farnsworth, Stan; Chrisey, Douglas; Escarra, Matthew

2018-08-03

This work reports a new technique for scalable and low-temperature processing of nanostructured TiO 2 thin films, allowing for practical manufacturing of TiO 2 -based devices such as perovskite solar cells at low-temperature or on flexible substrates. Dual layers of dense and mesoporous TiO 2 /graphitic oxide nanocomposite films are synthesized simultaneously using inkjet printing and pulsed photonic irradiation. Investigation of process parameters including precursor concentration (10-20 wt%) and exposure fluence (4.5-8.5 J cm -2 ) reveals control over crystalline quality, graphitic oxide phase, film thickness, dendrite density, and optical properties. Raman spectroscopy shows the E g peak, characteristic of anatase phase titania, increases in intensity with higher photonic irradiation fluence, suggesting increased crystallinity through higher fluence processing. Film thickness and dendrite density is shown to increase with precursor concentration in the printed ink. The dense base layer thickness was controlled between 20 and 80 nm. The refractive index of the films is determined by ellipsometry to be 1.92 ± 0.08 at 650 nm. Films exhibit an energy weighted optical transparency of 91.1%, in comparison to 91.3% of a thermally processed film, when in situ carbon materials were removed. Transmission and diffuse reflectance are used to determine optical band gaps of the films ranging from 2.98 to 3.38 eV in accordance with the photonic irradiation fluence and suggests tunability of TiO 2 phase composition. The sheet resistance of the synthesized films is measured to be 14.54 ± 1.11 Ω/□ and 28.90 ± 2.24 Ω/□ for films as-processed and after carbon removal, respectively, which is comparable to high temperature processed TiO 2 thin films. The studied electrical and optical properties of the light processed films show comparable results to traditionally processed TiO 2 while offering the distinct advantages of scalable manufacturing, low-temperature processing, simultaneous bilayer fabrication, and in situ formation of removable carbon nanocomposites.

Biosynthesis of titanium dioxide nanoparticles using Bacillus amyloliquefaciens culture and enhancement of its photocatalytic activity for the degradation of a sulfonated textile dye Reactive Red 31.

PubMed

Khan, Razia; Fulekar, M H

2016-08-01

The present study aims at exploiting Bacillus amyloliquefaciens for the biosynthesis of titanium dioxide nanoparticles and also investigates role of bacterial enzymes in the biosynthesis of titanium dioxide nanoparticles. Bacterial synthesized as well as metal doped titanium dioxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDAX). Amylase activity (43.37IU) in culture supernatant evinced a potential involvement of extracellular enzyme in TiO2 nanoparticle biosynthesis. Crystallite size of bio-synthesized nanoparticles was found to be in the range of 15.23-87.6nm. FTIR spectroscopy and native-PAGE (Polyacrylamide Gel Electrophoresis) clearly indicated involvement of alpha amylase in biosynthesis of TiO2 nanoparticles and in their stabilization. TEM micrographs of the synthesized titanium dioxide nanoparticles revealed the formation of spherical nanoparticles with a size range of 22.11-97.28nm. Photocatalytic degradation of Reactive Red 31 (RR31) dye was carried out using bio-synthesized TiO2 nanoparticles under UV radiation. Photocatalytic activity of synthesized nanoparticles was enhanced by Ag, La, Zn and Pt doping. Platinum doped TiO2 showed highest potential (90.98%) in RR31 degradation as compared to undoped (75.83%). Copyright © 2016 Elsevier Inc. All rights reserved.

Fibrochondrocyte Growth and Functionality on TiO2 Nanothin Films

PubMed Central

Ronald, Sharon; Mills, David K.

2016-01-01

Disorders affecting the temporomandibular joint (TMJ) are a long-standing health concern. TMJ disorders (TMJD) are often associated with an internal disc derangement accompanied by a suite of symptoms including joint noises, jaw dysfunction, and severe pain. The severity of patient symptoms and their reoccurrence can be alleviated to some extent with conservative therapy; however, refractory cases often require surgery that has shown only limited success. Bioengineered scaffolds with cell supportive surfaces an d nanoarchitectures that mimic TMJ tissue structure may offer an alternative treatment modality. In this study, titanium dioxide (TiO2) nanothin films, fabricated by layer-by-layer assembly, were examined as means for creating such a scaffold. The viability and growth of TMJ discal fibrochondrocytes (FCs) were assessed through MTT and DNA assays and total protein content over a 14-day experimental period. ELISA was also used to measure expression of types I and II collagen, decorin and aggrecan. Quantitative analyses demonstrated that FCs synthesized characteristic discal matrix proteins, with an increased production of type I collagen and decorin as opposed to collagen type II and aggrecan. A stimulatory effect on discal FC proliferation and extracellular matrix (ECM) expression with thicker nanofilms was also observed. The cumulative results suggest that TiO2 nanofilms may have potential as a TMJ scaffolding material. PMID:27314395

The photovoltaic efficiency of the fabrication of copolymer P3HT:PCBM on different thickness nano-anatase titania as solar cell

NASA Astrophysics Data System (ADS)

Lazim, Haidar Gazy; Ajeel, Khalid I.; Badran, Hussain A.

2015-06-01

Organic solar cells based on (3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM) bulk heterojunction (BHJ) with an inverted structure have been fabricated using nano-anatase crystalline titanium dioxide (TiO2) as their electron transport layer, which was prepared on the indium tin oxide coated glass (ITO-glass), silicon wafer and glass substrates by sol-gel method at different spin speed by using spin-coating (1000, 2000 and 3000 rpm) for nano-thin film 58, 75 and 90 nm respectively. The effect of thickness on the surface morphology and optical properties of TiO2 layer were investigated by atomic force microscopy (AFM), X-ray diffraction and UV-visible spectrophotometer. The optical band gap of the films has been found to be in the range 3.63-3.96 eV for allowed direct transition and to be in the range 3.23-3.69 eV for forbidden direct transition to the different TiO2 thickness. The samples were examined to feature current and voltages darkness and light extraction efficiency of the solar cell where they were getting the highest open-circuit voltage, Voc, and power conversion efficiency were 0.66% and 0.39% fabricated with 90 nm respectively.

Biological effect of food additive titanium dioxide nanoparticles on intestine: an in vitro study.

PubMed

Song, Zheng-Mei; Chen, Ni; Liu, Jia-Hui; Tang, Huan; Deng, Xiaoyong; Xi, Wen-Song; Han, Kai; Cao, Aoneng; Liu, Yuanfang; Wang, Haifang

2015-10-01

Titanium dioxide nanoparticles (TiO2 NPs) are widely found in food-related consumer products. Understanding the effect of TiO2 NPs on the intestinal barrier and absorption is essential and vital for the safety assessment of orally administrated TiO2 NPs. In this study, the cytotoxicity and translocation of two native TiO2 NPs, and these two TiO2 NPs pretreated with the digestion simulation fluid or bovine serum albumin were investigated in undifferentiated Caco-2 cells, differentiated Caco-2 cells and Caco-2 monolayer. TiO2 NPs with a concentration less than 200 µg ml(-1) did not induce any toxicity in differentiated cells and Caco-2 monolayer after 24 h exposure. However, TiO2 NPs pretreated with digestion simulation fluids at 200 µg ml(-1) inhibited the growth of undifferentiated Caco-2 cells. Undifferentiated Caco-2 cells swallowed native TiO2 NPs easily, but not pretreated NPs, implying the protein coating on NPs impeded the cellular uptake. Compared with undifferentiated cells, differentiated ones possessed much lower uptake ability of these TiO2 NPs. Similarly, the traverse of TiO2 NPs through the Caco-2 monolayer was also negligible. Therefore, we infer the possibility of TiO2 NPs traversing through the intestine of animal or human after oral intake is quite low. This study provides valuable information for the risk assessment of TiO2 NPs in food. Copyright © 2015 John Wiley & Sons, Ltd.

Photocatalytic removal of phenol over titanium dioxide- reduced graphene oxide photocatalyst

NASA Astrophysics Data System (ADS)

Shuhada Alim, Nor; Lintang, Hendrik O.; Yuliati, Leny

2016-02-01

Titanium dioxide (TiO2) has been one of the most investigated semiconductors due to its high activity for the removal of organic pollutants. In order to improve the efficiency of the TiO2, series of TiO2-reduced graphene oxide (rGO) composites with various loading amounts of graphene oxide (GO), which were 0.5, 1, 3 and 5 wt% were prepared by UV- assisted photocatalytic reduction method. The X-ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) spectra confirmed that all the TiO2-rGO composites samples were successfully synthesized without disrupting the structure of the TiO2. Fluorescence spectroscopy revealed the role of the rGO to reduce the electron-hole recombination on the TiO2, while the transmission electron microscopy-energy dispersive X- ray spectroscopy (TEM-EDS) confirmed the morphology and the presence of both TiO2 and rGO. In the photocatalytic removal of phenol, all the TiO2-rGO composites showed better photocatalytic activities than the TiO2 under UV light irradiation. The activity of the TiO2 was enhanced by more than two times with the addition of the GO with the optimum amount (3 wt%). It was proposed that the good photocatalytic performance obtained on the composites were caused by the successful suppression of electron-hole recombination by the rGO on the TiO2.

Targeted sonocatalytic cancer cell injury using avidin-conjugated titanium dioxide nanoparticles.

PubMed

Ninomiya, Kazuaki; Fukuda, Aya; Ogino, Chiaki; Shimizu, Nobuaki

2014-09-01

In this study, we applied sonodynamic therapy to cancer cells based on the delivery of titanium dioxide (TiO2) nanoparticles (NPs) modified with avidin protein, which preferentially discriminated cancerous cells from healthy cells. Subsequently, hydroxyl radicals were generated from the TiO2 NPs after activation by external ultrasound irradiation (TiO2/US treatment). Although 30% of the normal breast cells (human mammary epithelial cells) exhibited the uptake of avidin-modified TiO2 NPs, over 80% of the breast cancer cells (MCF-7) exhibited the uptake of avidin-TiO2 NPs. Next the effect of the TiO2/US treatment on MCF-7 cell growth was examined for up to 96 h after 1-MHz ultrasound was applied (0.1 W/cm(2), 30 s) to cells that incorporated the TiO2 NPs. No apparent cell injury was observed until 24h after the treatment, but the viable cell concentration declined to 68% compared with the control at 96 h. Copyright © 2014 Elsevier B.V. All rights reserved.

Immunomodulatory properties of titanium dioxide nanostructural materials.

PubMed

Latha, T Sree; Reddy, Madhava C; R Durbaka, Prasad V; Muthukonda, Shankar V; Lomada, Dakshayani

2017-01-01

Although titanium dioxide (TiO 2 ) nanostructural materials have been widely used in Biology and Medicine, very little is known about immunomodulation mechanism of these materials. Objectives of this study are to investigate in vitro immunomodulatory effects of TiO 2 . Immunosuppressant may lower immune responses and are helpful for the treatment of graft versus host diseases and autoimmune disorders. In this study, we used H 2 Ti 3 O 7 titanium dioxide nanotubes (TNT) nanotubes along with commercial TiO 2 nanoparticles (TNP) and TiO 2 fine particles (TFP). We investigated the in vitro immunomodulatory effects of TNP, TNT, and TFP using mixed lymphocyte reaction (MLR). Suppression was studied by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Cytokine profile was measured by enzyme-linked immunosorbent assay (ELISA). The results from this study illustrated that the TiO 2 nanostructural materials strongly suppressed splenocytes proliferation in MLR. For TNP and TNT, at 50 μg/ml suppression of 20%-25% and 30%-35%, respectively, and for TFP at 100 μg/ml suppression was 25%-30% was observed. Suppression of splenocytes proliferation in the presence of TNP, TNT, and TFP demonstrated that these nanostructural materials probably block T-cell-mediated responses in vitro . Our ELISA results confirmed that significantly lower levels of Th1 type cytokines (interleukin-2, interferon-γ) in the 48 h MLR culture supernatants. Our data suggest that TiO 2 nanostructural materials suppress splenocytes proliferation by suppressing Th1 cytokines.

Structural and fractal characterization of tungstophosphoric acid modified titanium dioxide photocatalyst

NASA Astrophysics Data System (ADS)

Petrović, S.; Rožić, Lj; Vuković, Z.; Grbić, B.; Radić, N.; Stojadinović, S.; Vasilić, R.

2017-04-01

This article presents the comparison of structural and fractal properties of nanocrystalline titanium dioxide (TiO2) and TiO2 modified with tungstophosphoric acid (TiO2/HPW) and their impact on the photocatalytic degradation of hazardous water pollutants. TiO2 and TiO2/HPW samples were synthesized by a combined sol-gel and hydrothermal processing. The XRD analysis of pure TiO2 samples revealed that phase composition was mainly dependent on the calcination temperature, changing from amorphous TiO2 to crystalline anatase and rutile by increasing the temperature. On the other hand, the XRD of TiO2/HPW samples calcined at temperatures above 600 °C showed crystalline peaks associated to formation of WO3 and WO2.92 crystalline domains. The N2 adsorption-desorption isotherm and pore size distribution of TiO2/HPW samples detected the existence of mesoporous characteristic with very narrow bimodal pores in the mesoporous region. The structural heterogeneity of samples was analyzed by means of pore size distribution functions, while the variation in fractal dimension were determined from the nitrogen adsorption isotherms, using the modified Frenkel-Halsey-Hill method. The results demonstrate that the approach is capable of characterizing complex textures such as those present in the TiO2 and TiO2/HPW photocatalysts. Besides, the effect of calcinations condition on photocatalytic properties of the samples was also investigated. The highest efficiency with respect to methyl orange photodecomposition was observed for TiO2/HPW photocatalysts calcined at 700 °C.

Laboratory Study on the Fatigue Resistance of Asphaltic Concrete Containing Titanium Dioxide

NASA Astrophysics Data System (ADS)

Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Azhar Tajudin, Saiful; Khatijah Abu Bakar, Siti

2018-03-01

This study aims to evaluate the fatigue performance of modified asphalt mixture using Indirect Tensile Fatigue Test. Titanium Dioxide (TiO2) powder in a form of rutile was used for producing asphalt concrete with lower mixing and compaction temperature compared to conventional hot mix asphalt without reducing its physical and mechanical also resistance to fatigue. The characteristic of the asphalt and modified asphalt was evaluated using penetration test, softening test and rotational viscosity test. Titanium dioxide of 2%, 4%, 6%, 8% and 10% by weight of asphalt has been incorporated into unaged 80/100 asphalt mix in order to improvise its performance and to fulfill the objectives of this experimental study. As a result, TiO2 as an additive is potential to decrease the penetration and increasing the softening point of the asphalt. In terms of fatigue performance testing, addition TiO2 additive does help in improving the fatigue properties as it shows greater result than the control asphalt. In conclusion, TiO2 is great in improving fatigue properties.

Electron microscopic investigation and elemental analysis of titanium dioxide in sun lotion.

PubMed

Sysoltseva, M; Winterhalter, R; Wochnik, A S; Scheu, C; Fromme, H

2017-06-01

The objective of this research was to determine the size, shape and aggregation of titanium dioxide (TiO 2 ) particles which are used in sun lotion as UV-blocker. Overall, six sunscreens from various suppliers and two reference substances were analysed by electron microscopy (EM) techniques in combination with energy dispersive X-ray spectroscopy (EDS). Because of a high fat content in sun lotion, it was impossible to visualize the TiO 2 particles without previous EM sample preparation. Different defatting methods for TiO 2 from sun screens were tested. A novel sample preparation method was developed which allowed the characterization of TiO 2 particles with the help of EM and EDS. Aggregates of titanium dioxide with the size of primary particles varying between 15 and 40 nm were observed only in five products. In the sun lotion with the highest SPF, only few small aggregates were found. In the sun screen with the lowest SPF, the largest aggregates of TiO 2 particles were detected with sizes up to 1.6 μm. In one of the sun lotions, neither TiO 2 nor ZnO was found in spite of the labelling. Instead, approx. 500 nm large diamond-shaped particles were observed. These particles are composed of an organic material as only carbon was detected by EDS. A novel defatting method for sample preparation of titanium dioxide nanoparticles used in sun cosmetics was developed. This method was applied to six different sun lotions with SPF between 30 and 50+. TiO 2 particles were found in only five sunscreens. The sizes of the primary particles were below 100 nm and, according to the EU Cosmetic Regulation, have to be listed on the package with the term 'nano'. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Effects of titanium dioxide nanoparticles isolated from confectionery products on the metabolic stress pathway in human lung fibroblast cells.

PubMed

Periasamy, Vaiyapuri Subbarayan; Athinarayanan, Jegan; Al-Hadi, Ahmed M; Juhaimi, Fahad Al; Alshatwi, Ali A

2015-04-01

Titanium dioxide (TiO2) is a common additive in many foods, pigments, personal care products, and other consumer products used in daily life. Despite the widespread use of nanoscale TiO2 and composites of nanoscale TiO2 in the food industry, there is a serious lack of awareness of the toxicity of TiO2 nanoparticles (NPs) among consumers and manufacturers. There is an urgent need for toxicological studies of TiO2 NPs. TiO2 food additives separated from marketed foods were characterized by transmission electron microscopy. In addition, the effects of TiO2 NPs on metabolic stress in WI-38 cells were analyzed. Cell viability, total ROS, mitochondrial transmembrane potential (ΔψM), cell cycle, and metabolism-related gene expression were analyzed. The results indicate that TiO2 NPs have a significant concentration-dependent toxic effect in lung cells. The ΔψM, the intracellular ROS level, and the stages of the WI-38 cell cycle were altered by increasing TiO2 concentrations after exposure for 24 and 48 h relative to the control. Cytochrome P450 1A, GSTM3, and glutathione S-transferase A4 upregulation in response to the TiO2 NPs was observed. These findings suggest that the toxicity of TiO2 from confectionery products in WI-38 cells may be mediated through an increase in oxidative stress. The results of this study clearly demonstrate the nanotoxicological effects of TiO2 on WI-38 cells and will be useful for nanotoxicological indexing.

A review on methods of synthesizing nanostructures TiO2

NASA Astrophysics Data System (ADS)

Munirah, S.; Nadzirah, Sh.; Khusaimi, Z.; Fazlena, H.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) is a well-known materials and being extensively investigated due to the stability of the chemical structure, optical, physical, and electrical properties, also its biocompatibility. There are a lot of efforts have been done to synthesis TiO2 since the previous years by using different kind of methods. In this review paper, we summarize the methods of synthesizing nanostructured TiO2.

Characterization and morphology of prepared titanium dioxide nanofibers by electrospinning.

PubMed

Park, Ju-Young; Lee, In-Hwa

2010-05-01

Dispersed titanium dioxide in polymer nanofibers were prepared by sol-gel processing and electrospinning techniques using titanium isopropoxide (TiP)/polyvinylpyrrolidone (PVP) solution. The prepared titanium dioxide nanofibers were characterized by FE-SEM, TEM, XRD, and FT-IR. Pure titanium dioxide nanofibers were obtained from calcination of inorganic-organic composite fiber. The diameter of titanium oxide nanofibers were in the range of 70 nm to 150 nm. Prepared titanium dioxide nanofibers show rough surface and rather small diameter compare with TiP/PVP composite nanofibers. After calcined at 500 degrees C, TiO2 nanofibers convert into anatase and rutile mixed phased from amorphous structure. Calcination of these composite fibers above 600 degrees C resulted in pure rutile TiO2 nanofibers.

In situ effects of titanium dioxide nanoparticles on community structure of freshwater benthic macroinvertebrates.

PubMed

Jovanović, Boris; Milošević, Djuradj; Piperac, Milica Stojković; Savić, Ana

2016-06-01

For the first time in the current literature, the effect of titanium dioxide (TiO2) nanoparticles on the community structure of macroinvertebrates has been investigated in situ. Macroinvertebrates were exposed for 100 days to an environmentally relevant concentration of TiO2 nanoparticles, 25 mg kg(-1) in sediment. Czekanowski's index was 0.61, meaning 39% of the macroinvertebrate community structure was affected by the TiO2 treatment. Non-metric multidimensional scaling (NMDS) visualized the qualitative and quantitative variability of macroinvertebrates at the community level among all samples. A distance-based permutational multivariate analysis of variance (PERMANOVA) revealed the significant effect of TiO2 on the macroinvertebrate community structure. The indicator value analysis showed that the relative frequency and abundance of Planorbarius corneus and Radix labiata were significantly lower in the TiO2 treatment than in the control. Meanwhile, Ceratopogonidae, showed a significantly higher relative frequency and abundance in the TiO2 treatment than in the control. Copyright © 2016 Elsevier Ltd. All rights reserved.

Realistic Evaluation of Titanium Dioxide Nanoparticle Exposure in Chewing Gum.

PubMed

Fiordaliso, Fabio; Foray, Claudia; Salio, Monica; Salmona, Mario; Diomede, Luisa

2018-06-20

There is growing concern about the presence of nanoparticles (NPs) in titanium dioxide (TiO 2 ) as food additive (E171). To realistically estimate the number and the amount of TiO 2 NPs ingested with food, we applied a transmission electron microscopy method combined with inductively coupled plasma optical emission spectrometry. Different percentages of TiO 2 NPs (6-18%) were detected in E171 from various suppliers. In the eight chewing gums analyzed as food prototypes, TiO 2 NPs were absent in one sample and ranged 0.01-0.66 mg/gum, corresponding to 7-568 billion NPs/gum, in the other seven. We estimated that the mass-based TiO 2 NPs ingested with chewing gums by the European population ranged from 0.28 to 112.40 μg/kg b.w./day, and children ingested more nanosized titanium than adolescents and adults. Although this level may appear negligible it corresponds to 0.1-84 billion TiO 2 NPs/kg b.w/day, raising important questions regarding their potential accumulation in the body, possibly causing long-term effects on consumers' health.

Antibacterial Properties of Visible-Light-Responsive Carbon-Containing Titanium Dioxide Photocatalytic Nanoparticles against Anthrax

PubMed Central

Sun, Der-Shan; Kau, Jyh-Hwa; Huang, Hsin-Hsien; Tseng, Yao-Hsuan; Wu, Wen-Shiang; Chang, Hsin-Hou

2016-01-01

The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to be a visible-light-responsive photocatalyst (VLRP), which displayed significantly enhanced antibacterial properties under visible light illumination. However, whether TiO2(C) NPs exert antibacterial properties against Bacillus anthracis remains elusive. Here, we evaluated these VLRP NPs in the reduction of anthrax-induced pathogenesis. Bacteria-killing experiments indicated that a significantly higher proportion (40%–60%) of all tested Bacillus species, including B. subtilis, B. cereus, B. thuringiensis, and B. anthracis, were considerably eliminated by TiO2(C) NPs. Toxin inactivation analysis further suggested that the TiO2(C) NPs efficiently detoxify approximately 90% of tested anthrax lethal toxin, a major virulence factor of anthrax. Notably, macrophage clearance experiments further suggested that, even under suboptimal conditions without considerable bacterial killing, the TiO2(C) NP-mediated photocatalysis still exhibited antibacterial properties through the reduction of bacterial resistance against macrophage killing. Our results collectively suggested that TiO2(C) NP is a conceptually feasible anti-anthrax material, and the relevant technologies described herein may be useful in the development of new strategies against anthrax. PMID:28335365

Characterization of the Interactions between Titanium Dioxide Nanoparticles and Polymethoxyflavones Using Surface-Enhanced Raman Spectroscopy.

PubMed

Cao, Xiaoqiong; Ma, Changchu; Gao, Zili; Zheng, Jinkai; He, Lili; McClements, David Julian; Xiao, Hang

2016-12-14

Nanosized titanium dioxide (TiO 2 ) particles are commonly present in TiO 2 food additives (E171) and have been associated with potential adverse effects on health. However, little knowledge is available regarding the interactions between TiO 2 nanoparticles (NPs) and other food components, such as flavonoids. In this study, we aim to study the molecular interactions between TiO 2 anatase NPs and three structurally closely related polymethoxyflavones (PMFs, flavonoids found in citrus fruits), namely, 3',4'-didemethylnobiletin (DDN), 5-demethylnobiletin (5DN), and 5,3',4'-tridemethylnobiletin (TDN), using ultraviolet-visible (UV-vis) spectrometry and surface-enhanced Raman spectroscopy (SERS). In the UV-vis absorption spectra, bathochromic effects were observed after DDN and TDN conjugated with TiO 2 NPs. The results from SERS analysis clearly demonstrated that DDN and TDN could bind TiO 2 NPs with the functional groups 3'-OH and 4'-OH on ring B and formed charge-transfer complexes. However, 5DN with functional groups C═O on ring C and 5-OH on ring A could not bind TiO 2 NPs. Knowledge on the molecular interactions between TiO 2 NPs and food components, such as flavonoids, will facilitate the understanding of the fate of TiO 2 NPs during food processing and in the gastrointestinal tract after oral consumption.

Cytotoxicity of titanium dioxide nanoparticles in mouse fibroblast cells.

PubMed

Jin, Cheng-Yu; Zhu, Bang-Shang; Wang, Xue-Feng; Lu, Qing-Hua

2008-09-01

Nanotitanium dioxide (TiO2) is an important industrial material that is widely used as an additive in cosmetics, pharmaceuticals, and food colorants. Although the small size of the TiO2 nanoparticle is useful in various applications, the biosafety of this material needs to be evaluated. In this study, mouse fibroblast (L929) cells were used to evaluate the cytotoxicity of different concentrations (3-600 microg/mL) of homogeneous and weakly aggregated TiO2 nanoparticles in aqueous solution. The L929 cells became round and even shrank as the concentration of TiO2 nanoparticles increased. Moreover, TiO2 nanoparticle-treated cells had condensed fragmented chromatin or were directly necrosed, as observed by acridine orange (AO) staining. The transmission electron microscopy (TEM) analysis showed that in cells cultured in a medium containing 300 microg/mL TiO2, the number of lysosomes increased, and some cytoplasmic organelles were damaged. In addition, there was a significant increase in oxidative stress at higher TiO2 nanoparticle concentrations (>60 microg/mL). As the concentration of TiO2 nanoparticles increased in the culture medium, the levels of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) increased, while those of methyl tetrazolium cytotoxicity (MTT), glutathione (GSH), and superoxide dismutase (SOD) decreased. A possible mechanism for the cytotoxicity of TiO2 nanoparticles is also discussed.

Transverse mode control in proton-implanted and oxide-confined VCSELs via patterned dielectric anti-phase filters

NASA Astrophysics Data System (ADS)

Kesler, Benjamin; O'Brien, Thomas; Dallesasse, John M.

2017-02-01

A novel method for controlling the transverse lasing modes in both proton implanted and oxide-confined vertical- cavity surface-emitting lasers (VCSELs) with a multi-layer, patterned, dielectric anti-phase (DAP) filter is pre- sented. Using a simple photolithographic liftoff process, dielectric layers are deposited and patterned on individual VCSELs to modify (increase or decrease) the mirror reflectivity across the emission aperture via anti-phase reflections, creating spatially-dependent threshold material gain. The shape of the dielectric pattern can be tailored to overlap with specific transverse VCSEL modes or subsets of transverse modes to either facilitate or inhibit lasing by decreasing or increasing, respectively, the threshold modal gain. A silicon dioxide (SiO2) and titanium dioxide (TiO2) anti-phase filter is used to achieve a single-fundamental-mode, continuous-wave output power greater than 4.0 mW in an oxide-confined VCSEL at a lasing wavelength of 850 nm. A filter consisting of SiO2 and TiO2 is used to facilitate injection-current-insensitive fundamental mode and lower order mode lasing in proton implanted VCSELs at a lasing wavelength of 850 nm. Higher refractive index dielectric materials such as amorphous silicon (a-Si) can be used to increase the effectiveness of the anti-phase filter on proton implanted devices by reducing the threshold modal gain of any spatially overlapping modes. This additive, non-destructive method allows for mode selection at any lasing wavelength and for any VCSEL layer structure without the need for semiconductor etching or epitaxial regrowth. It also offers the capability of designing a filter based upon available optical coating materials.

Films of brookite TiO2 nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO2 gas-sensing layers

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Buonsanti, R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Taurino, A.; Rella, R.

2011-09-01

Titanium dioxide (TiO2) nanorods in the brookite phase, with average dimensions of 3-4 nm × 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO2) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm2 and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of ˜150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 nanorods and crystalline spherical nanoparticles with an average diameter of ˜13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO2 mixed in dry air were obtained.

Pulmonary toxicity of well-dispersed titanium dioxide nanoparticles following intratracheal instillation

NASA Astrophysics Data System (ADS)

Yoshiura, Yukiko; Izumi, Hiroto; Oyabu, Takako; Hashiba, Masayoshi; Kambara, Tatsunori; Mizuguchi, Yohei; Lee, Byeong Woo; Okada, Takami; Tomonaga, Taisuke; Myojo, Toshihiko; Yamamoto, Kazuhiro; Kitajima, Shinichi; Horie, Masanori; Kuroda, Etsushi; Morimoto, Yasuo

2015-06-01

In order to investigate the pulmonary toxicity of titanium dioxide (TiO2) nanoparticles, we performed an intratracheal instillation study with rats of well-dispersed TiO2 nanoparticles and examined the pulmonary inflammation and histopathological changes in the lung. Wistar Hannover rats were intratracheally administered 0.2 mg (0.66 mg/kg) and 1.0 mg (3.3 mg/kg) of well-dispersed TiO2 nanoparticles (P90; diameter of agglomerates: 25 nm), then the pulmonary inflammation responses were examined from 3 days to 6 months after the instillation, and the pathological features were examined up to 24 months. Transient inflammation and the upregulation of chemokines in the broncho-alveolar lavage fluid were observed for 1 month. No respiratory tumors or severe fibrosis were observed during the recovery time. These data suggest that transient inflammation induced by TiO2 may not lead to chronic, irreversible legions in the lung, and that TiO2 nanoparticles may not have a high potential for lung disorder.

Interfacial band-edge engineered TiO2 protection layer on Cu2O photocathodes for efficient water reduction reaction

NASA Astrophysics Data System (ADS)

Choi, Jaesuk; Song, Jun Tae; Jang, Ho Seong; Choi, Min-Jae; Sim, Dong Min; Yim, Soonmin; Lim, Hunhee; Jung, Yeon Sik; Oh, Jihun

2017-01-01

Photoelectrochemical (PEC) water splitting has emerged as a potential pathway to produce sustainable and renewable chemical fuels. Here, we present a highly active Cu2O/TiO2 photocathode for H2 production by enhancing the interfacial band-edge energetics of the TiO2 layer, which is realized by controlling the fixed charge density of the TiO2 protection layer. The band-edge engineered Cu2O/TiO2 (where TiO2 was grown at 80 °C via atomic layer deposition) enhances the photocurrent density up to -2.04 mA/cm2 at 0 V vs. RHE under 1 sun illumination, corresponding to about a 1,200% enhancement compared to the photocurrent density of the photocathode protected with TiO2 grown at 150 °C. Moreover, band-edge engineering of the TiO2 protection layer prevents electron accumulation at the TiO2 layer and enhances both the Faraday efficiency and the stability for hydrogen production during the PEC water reduction reaction. This facile control over the TiO2/electrolyte interface will also provide new insight for designing highly efficient and stable protection layers for various other photoelectrodes such as Si, InP, and GaAs. [Figure not available: see fulltext.

The role of poly(methacrylic acid) conformation on dispersion behavior of nano TiO2 powder

NASA Astrophysics Data System (ADS)

Singh, Bimal P.; Nayak, Sasmita; Samal, Samata; Bhattacharjee, Sarama; Besra, Laxmidhar

2012-02-01

To exploit the advantages of nanoparticles for various applications, controlling the dispersion and agglomeration is of paramount importance. Agglomeration and dispersion behavior of titanium dioxide (TiO2) nanoparticles was investigated using electrokinetic and surface chemical properties. Nanoparticles are generally stabilized by the adsorption of a dispersant (polyelectrolyte) layer around the particle surface and in this connection ammonium salt of polymethacrylic acid (Darvan C) was used as dispersant to stabilize the suspension. The dosages of polyelectrolyte were optimized to get best dispersion stability by techniques namely particle charge detector (13.75 mg/g) and adsorption (14.57 mg/g). The surface charge of TiO2 particles changed significantly in presence of dispersant Darvan C and isoelectric point (iep) shifted significantly towards lower pH from 5.99 to 3.37. The shift in iep has been quantified in terms of free energy of interaction between the surface sites of TiO2 and the adsorbing dispersant Darvan C. Free energies of adsorption were calculated by electrokinetic data (-9.8 RT unit) and adsorption isotherms (-10.56 RT unit), which corroborated well. The adsorption isotherms are of typical Langmuir type and employed for calculation of free energy. The results indicated that adsorption occurs mainly through electrostatic interactions between the dispersant molecule and the TiO2 surface apart from hydrophobic interactions.

An electrochemical aptasensor based on a TiO2/three-dimensional reduced graphene oxide/PPy nanocomposite for the sensitive detection of lysozyme.

PubMed

Wang, Minghua; Zhai, Shuyong; Ye, Zihan; He, Linghao; Peng, Donglai; Feng, Xiaozhong; Yang, Yanqin; Fang, Shaoming; Zhang, Hongzhong; Zhang, Zhihong

2015-04-14

A sensitive aptasensor based on a nanocomposite of hollow titanium dioxide nanoball, three-dimensional reduced graphene oxide, and polypyrrole (TiO2/3D-rGO/PPy) was developed for lysozyme detection. A lysozyme aptamer was easily immobilized onto the TiO2/3D-rGO/PPy nanocomposite matrix by assembling the aptamer onto graphene through simple π-stacking interactions and electrostatic interactions between PPy molecular chains and aptamer strands. In the presence of lysozyme, the aptamer on the adsorbent layer catches the target on the electrode interface, which generates a barrier for electrons and inhibits electron transfer, subsequently resulting in decreased electrochemically differential pulse voltammetric signals of a gold electrode modified with TiO2/3D-rGO/PPy. Using this strategy, a low limit of detection of 0.085 ng mL(-1) (5.5 pM) for detecting lysozyme was observed within the detection range of 0.1-50 ng mL(-1) (0.007-3.5 nM). The aptasensor also presents high specificity for lysozyme, which is unaffected by the coexistence of other proteins. Such an aptasensor opens a rapid, selective, and sensitive route to lysozyme detection. This finding indicates that the TiO2/3D-rGO/PPy nanocomposite could be used as an electrochemical biosensor for detecting proteins in the biomedical field.

Effects of titanium dioxide nanoparticles on human keratinocytes

PubMed Central

Wright, Clayton; Iyer, Anand Krishnan V.; Wang, Liying; Wu, Nianqiang; Yakisich, Juan S.; Rojanasakul, Yon; Azad, Neelam

2016-01-01

Titanium dioxide (TiO2) is a ubiquitous whitening compound widely used in topical products such as sunscreens, lotions and facial creams. The damaging health effects of TiO2 inhalation has been widely studied in rats, mice and humans showing oxidative stress increase, DNA damage, cell death and inflammatory gene upregulation in lung and throat cells; however, the effects on skin cells from long-term topical use of various products remain largely unknown. In this study, we assessed the effect of specific TiO2 nanoparticles (H2TiO7) on a human keratinocyte cell line (HaCaT). We performed a comparative analysis using three TiO2 particles varying in size (Fine, Ultrafine and H2TiO7) and analyzed their effects on HaCaTs. There is a clear dose-dependent increase in superoxide production, caspase 8 and 9 activity, and apoptosis in HaCaTs after treatment with all three forms of TiO2; however, there is no consistent effect on cell viability and proliferation with either of these TiO2 particles. While there is data suggesting UV exposure can enhance the carcinogenic effects of TiO2, we did not observe any significant effect of UV-C exposure combined with TiO2 treatment on HaCaTs. Furthermore, TiO2-treated cells showed minimal effects on VEGF upregulation and Wnt signaling pathway thereby showing no potential effect on angiogenesis and malignant transformation. Overall, we report here an increase in apoptosis, which may be caspase 8/Fas-dependent, and that the H2TiO7 nanoparticles, despite their smaller particle size, had no significant enhanced effect on HaCaT cells as compared to Fine and Ultrafine forms of TiO2. PMID:27310834

The effect of titanium dioxide (TiO2) nano-objects, and their aggregates and agglomerates greater than 100nm (NOAA) on microbes under UV irradiation.

PubMed

Yamada, Ikuho; Nomura, Kazuki; Iwahashi, Hitoshi; Horie, Masanori

2016-01-01

Today, nanoparticles are used in many products. One of the most common nanoparticles is titanium dioxide (TiO2). These particles generate reactive oxygen species (ROS) upon UV irradiation. Although nanoparticles are very useful in many products, there are concerns about their biological and ecological effects when released into the environment. Thus, it was assessed that the effect of TiO2 nano-objects, and their aggregates and agglomerates greater than 100nm (NOAA) on microbes under UV irradiation by using Escherichia coli and Saccharomyces cerevisiae. ROS generation was evaluated by adding TiO2 nanoparticles and methylene blue to distilled water. We also assessed growth inhibition by adding TiO2 nanoparticles and microbes in minimal agar medium. Moreover, microbial inactivation was assessed by adding TiO2 nanoparticles and microbes to PBS. Upon UV irradiation, TiO2-NOAAs decomposed methylene blue and generated ROS. TiO2-NOAAs also decomposed methylene blue in minimal agar medium under UV irradiation; however, they did not inhibit microbial growth. Surprisingly, TiO2-NOAAs in the medium protect microbes from UV irradiation as colony formation was observed only near TiO2-NOAAs. In PBS, TiO2-NOAAs did not inactivate microbes but instead protected microbes from lethal UV irradiation. These results suggest that the amount of ROS generated by TiO2-NOAAs is not enough to inactivate microbes. In fact, our results suggest that TiO2-NOAAs may protect microbes from UV irradiations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Efficient planar Sb2S3 solar cells using a low-temperature solution-processed tin oxide electron conductor.

PubMed

Lei, Hongwei; Yang, Guang; Guo, Yaxiong; Xiong, Liangbin; Qin, Pingli; Dai, Xin; Zheng, Xiaolu; Ke, Weijun; Tao, Hong; Chen, Zhao; Li, Borui; Fang, Guojia

2016-06-28

Efficient planar antimony sulfide (Sb2S3) heterojunction solar cells have been made using chemical bath deposited (CBD) Sb2S3 as the absorber, low-temperature solution-processed tin oxide (SnO2) as the electron conductor and poly (3-hexylthiophene) (P3HT) as the hole conductor. A solar conversion efficiency of 2.8% was obtained at 1 sun illumination using a planar device consisting of F-doped SnO2 substrate/SnO2/CBD-Sb2S3/P3HT/Au, whereas the solar cells based on a titanium dioxide (TiO2) electron conductor exhibited a power conversion efficiency of 1.9%. Compared with conventional Sb2S3 sensitized solar cells, the high-temperature processed mesoscopic TiO2 scaffold is no longer needed. More importantly, a low-temperature solution-processed SnO2 layer was introduced for electron transportation to substitute the high-temperature sintered dense blocking TiO2 layer. Our planar solar cells not only have simple geometry with fewer steps to fabricate but also show enhanced performance. The higher efficiency of planar Sb2S3 solar cell devices based on a SnO2 electron conductor is attributed to their high transparency, uniform surface, efficient electron transport properties of SnO2, suitable energy band alignment, and reduced recombination at the interface of SnO2/Sb2S3.

Photoinduced electron transfer in perylene-TiO2 nanoassemblies.

PubMed

Llansola-Portoles, Manuel J; Bergkamp, Jesse J; Tomlin, John; Moore, Thomas A; Kodis, Gerdenis; Moore, Ana L; Cosa, Gonzalo; Palacios, Rodrigo E

2013-01-01

The photosensitization effect of three perylene dye derivatives on titanium dioxide nanoparticles (TiO2 NPs) has been investigated. The dyes used, 1,7-dibromoperylene-3,4,9,10-tetracarboxy dianhydride (1), 1,7-dipyrrolidinylperylene-3,4,9,10-tetracarboxy dianhydride (2) and 1,7-bis(4-tert-butylphenyloxy)perylene-3,4,9,10-tetracarboxy dianhydride (3) have in common bisanhydride groups that convert into TiO2 binding groups upon hydrolysis. The different substituents on the bay position of the dyes enable tuning of their redox properties to yield significantly different driving forces for photoinduced electron transfer (PeT). Recently developed TiO2 NPs having a small average size and a narrow distribution (4 ± 1 nm) are used in this work to prepare the dye-TiO2 systems under study. Whereas successful sensitization was obtained with 1 and 2 as evidenced by steady-state spectral shifts and transient absorption results, no evidence for the attachment of 3 to TiO2 was observed. The comparison of the rates of PeT (kPeT ) for 1- and 2-TiO2 systems studied in this work with those obtained for previously reported analogous systems, having TiO2 NPs covered by a surfactant layer (Hernandez et al. [2012] J. Phys. Chem. B., 117, 4568-4581), indicates that kPeT for the former systems is slower than that for the later. These results are interpreted in terms of the different energy values of the conduction band edge in each system. © 2013 The American Society of Photobiology.

Titanium Dioxide Particle Type and Concentration Influence the Inflammatory Response in Caco-2 Cells

PubMed Central

Tada-Oikawa, Saeko; Ichihara, Gaku; Fukatsu, Hitomi; Shimanuki, Yuka; Tanaka, Natsuki; Watanabe, Eri; Suzuki, Yuka; Murakami, Masahiko; Izuoka, Kiyora; Chang, Jie; Wu, Wenting; Yamada, Yoshiji; Ichihara, Sahoko

2016-01-01

Titanium dioxide (TiO2) nanoparticles are widely used in cosmetics, sunscreens, biomedicine, and food products. When used as a food additive, TiO2 nanoparticles are used in significant amounts as white food-coloring agents. However, the effects of TiO2 nanoparticles on the gastrointestinal tract remain unclear. The present study was designed to determine the effects of five TiO2 particles of different crystal structures and sizes in human epithelial colorectal adenocarcinoma (Caco-2) cells and THP-1 monocyte-derived macrophages. Twenty-four-hour exposure to anatase (primary particle size: 50 and 100 nm) and rutile (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner in THP-1 macrophages, but in not Caco-2 cells. However, 72-h exposure of Caco-2 cells to anatase (50 nm) TiO2 particles reduced cellular viability in a dose-dependent manner. The highest dose (50 µg/mL) of anatase (100 nm), rutile (50 nm), and P25 TiO2 particles also reduced cellular viability in Caco-2 cells. The production of reactive oxygen species tended to increase in both types of cells, irrespective of the type of TiO2 particle. Exposure of THP-1 macrophages to 50 µg/mL of anatase (50 nm) TiO2 particles increased interleukin (IL)-1β expression level, and exposure of Caco-2 cells to 50 µg/mL of anatase (50 nm) TiO2 particles also increased IL-8 expression. The results indicated that anatase TiO2 nanoparticles induced inflammatory responses compared with other TiO2 particles. Further studies are required to determine the in vivo relevance of these findings to avoid the hazards of ingested particles. PMID:27092499

SiO2 and TiO2 nanoparticles synergistically trigger macrophage inflammatory responses.

PubMed

Tsugita, Misato; Morimoto, Nobuyuki; Nakayama, Masafumi

2017-04-11

Silicon dioxide (SiO 2 ) nanoparticles (NPs) and titanium dioxide (TiO 2 ) NPs are the most widely used inorganic nanomaterials. Although the individual toxicities of SiO 2 and TiO 2 NPs have been extensively studied, the combined toxicity of these NPs is much less understood. In this study, we observed unexpected and drastic activation of the caspase-1 inflammasome and production of IL-1β in mouse bone marrow-derived macrophages stimulated simultaneously with SiO 2 and TiO 2 NPs at concentrations at which these NPs individually do not cause macrophage activation. Consistent with this, marked lung inflammation was observed in mice treated intratracheally with both SiO 2 and TiO 2 NPs. In macrophages, SiO 2 NPs localized in lysosomes and TiO 2 NPs did not; while only TiO 2 NPs produced ROS, suggesting that these NPs induce distinct cellular damage leading to caspase-1 inflammasome activation. Intriguingly, dynamic light scattering measurements revealed that, although individual SiO 2 and TiO 2 NPs immediately aggregated to be micrometer size, the mixture of these NPs formed a stable and relatively monodisperse complex with a size of ~250 nm in the presence of divalent cations. Taken together, these results suggest that SiO 2 and TiO 2 NPs synergistically induce macrophage inflammatory responses and subsequent lung inflammation. Thus, we propose that it is important to assess the synergistic toxicity of various combinations of nanomaterials.

Ultra-fine structural characterization and bioactivity evaluation of TiO2 nanotube layers.

PubMed

Jang, JaeMyung; Kwon, TaeYub; Kim, KyoHan

2008-10-01

For an application as biomedical materials of high performance with a good biocompatibility, the TiO2 nanotube-type oxide film on Ti substrate has been fabricated by electrochemical method, and the effects of surface characteristics of TiO2 naotube layer have been investigated. The surface morphology of TiO2 nanotube layer depends on factors such as anodizing time, current density, and electrolyte temperature. Moreover, the cell and pore size gradually were increased with the passage of anodizing time. X-ray diffraction (XRD) results indicated that the TiO2 nanotube layer formed in acidic electrolytes was mainly composed of anatase structure containing rutile. From the analysis of chemical states of TiO2 nanotube layer using X-ray photoelectron spectroscopy (XPS), Ti2p, P2p and O1s were observed in the nanotubes layer, which were penetrated from the electrolyte into the oxide layer during anodic process. The incorporated phosphate species were found mostly in the forms of HPO4-, PO4-, and PO3-. From the result of biological evaluation in simulated body fluid (SBF) the TiO2 nanotube layer was effective for bioactive property.

Toxic effects of the interaction of titanium dioxide nanoparticles with chemicals or physical factors

PubMed Central

Liu, Kui; Lin, Xialu; Zhao, Jinshun

2013-01-01

Due to their chemical stability and nonallergic, nonirritant, and ultraviolet protective properties, titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in industries such as electronics, optics, and material sciences, as well as architecture, medicine, and pharmacology. However, increasing concerns have been raised in regards to its ecotoxicity and toxicity on the aquatic environment as well as to humans. Although insights have been gained into the effects of TiO2 NPs on susceptible biological systems, there is still much ground to be covered, particularly in respect of our knowledge of the effects of the interaction of TiO2 NPs with other chemicals or physical factors. Studies suggest that interactions of TiO2 NPs with other chemicals or physical factors may result in an increase in toxicity or adverse effects. This review highlights recent progress in the study of the interactive effects of TiO2 NPs with other chemicals or physical factors. PMID:23901269

Versatility of Evaporation-Induced Self-Assembly (EISA) Method for Preparation of Mesoporous TiO2 for Energy and Environmental Applications

PubMed Central

Mahoney, Luther; Koodali, Ranjit T.

2014-01-01

Evaporation-Induced Self-Assembly (EISA) method for the preparation of mesoporous titanium dioxide materials is reviewed. The versatility of EISA method for the rapid and facile synthesis of TiO2 thin films and powders is highlighted. Non-ionic surfactants such as Pluronic P123, F127 and cationic surfactants such as cetyltrimethylammonium bromide have been extensively employed for the preparation of mesoporous TiO2. In particular, EISA method allows for fabrication of highly uniform, robust, crack-free films with controllable thickness. Eleven characterization techniques for elucidating the structure of the EISA prepared mesoporous TiO2 are discussed in this paper. These many characterization methods provide a holistic picture of the structure of mesoporous TiO2. Mesoporous titanium dioxide materials have been employed in several applications that include Dye Sensitized Solar Cells (DSSCs), photocatalytic degradation of organics and splitting of water, and batteries. PMID:28788590

Sonochemical fabrication of fluorinated mesoporous titanium dioxide microspheres

NASA Astrophysics Data System (ADS)

Yu, Changlin; Yu, Jimmy C.; Chan, Mui

2009-05-01

A sonochemical-hydrothermal method for preparing fluorinated mesoporous TiO 2 microspheres was developed. Formation of mesoporous TiO 2 and doping of fluorine was achieved by sonication and then hydrothermal treatment of a solution containing titanium isopropoxide, template, and sodium fluoride. The as-synthesized TiO 2 microspheres were characterized by X-ray diffraction (XRD), Fourier translation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, photoluminescence spectroscopy (PL), and BET surface areas. The P123 template was removed completely during the hydrothermal and washing steps, which was different from the conventional calcination treatment. The as- synthesized TiO 2 microspheres had good crystallinity and high stability. Results from the photocatalytic degradation of methylene blue (MB) showed that fluorination could remarkably improve the photocatalytic activity of titanium dioxide.

Titanium dioxide nanoparticles: a review of current toxicological data.

PubMed

Shi, Hongbo; Magaye, Ruth; Castranova, Vincent; Zhao, Jinshun

2013-04-15

Titanium dioxide (TiO2) nanoparticles (NPs) are manufactured worldwide in large quantities for use in a wide range of applications. TiO2 NPs possess different physicochemical properties compared to their fine particle (FP) analogs, which might alter their bioactivity. Most of the literature cited here has focused on the respiratory system, showing the importance of inhalation as the primary route for TiO2 NP exposure in the workplace. TiO2 NPs may translocate to systemic organs from the lung and gastrointestinal tract (GIT) although the rate of translocation appears low. There have also been studies focusing on other potential routes of human exposure. Oral exposure mainly occurs through food products containing TiO2 NP-additives. Most dermal exposure studies, whether in vivo or in vitro, report that TiO2 NPs do not penetrate the stratum corneum (SC). In the field of nanomedicine, intravenous injection can deliver TiO2 nanoparticulate carriers directly into the human body. Upon intravenous exposure, TiO2 NPs can induce pathological lesions of the liver, spleen, kidneys, and brain. We have also shown here that most of these effects may be due to the use of very high doses of TiO2 NPs. There is also an enormous lack of epidemiological data regarding TiO2 NPs in spite of its increased production and use. However, long-term inhalation studies in rats have reported lung tumors. This review summarizes the current knowledge on the toxicology of TiO2 NPs and points out areas where further information is needed.

Titanium dioxide nanoparticles: a review of current toxicological data

PubMed Central

2013-01-01

Titanium dioxide (TiO2) nanoparticles (NPs) are manufactured worldwide in large quantities for use in a wide range of applications. TiO2 NPs possess different physicochemical properties compared to their fine particle (FP) analogs, which might alter their bioactivity. Most of the literature cited here has focused on the respiratory system, showing the importance of inhalation as the primary route for TiO2 NP exposure in the workplace. TiO2 NPs may translocate to systemic organs from the lung and gastrointestinal tract (GIT) although the rate of translocation appears low. There have also been studies focusing on other potential routes of human exposure. Oral exposure mainly occurs through food products containing TiO2 NP-additives. Most dermal exposure studies, whether in vivo or in vitro, report that TiO2 NPs do not penetrate the stratum corneum (SC). In the field of nanomedicine, intravenous injection can deliver TiO2 nanoparticulate carriers directly into the human body. Upon intravenous exposure, TiO2 NPs can induce pathological lesions of the liver, spleen, kidneys, and brain. We have also shown here that most of these effects may be due to the use of very high doses of TiO2 NPs. There is also an enormous lack of epidemiological data regarding TiO2 NPs in spite of its increased production and use. However, long-term inhalation studies in rats have reported lung tumors. This review summarizes the current knowledge on the toxicology of TiO2 NPs and points out areas where further information is needed. PMID:23587290

Application of thin dielectric films in low coherence fiber-optic Fabry-Pérot sensing interferometers: comparative study

NASA Astrophysics Data System (ADS)

Hirsch, Marzena; Wierzba, Paweł; Jedrzejewska-Szczerska, Małgorzata

2016-11-01

We examine the application of selected thin dielectric films, deposited by atomic layer deposition (ALD), in a low coherence fiber-optic Fabry-Pérot interferometer designed for sensing applications. Such films can be deposited on the end-face of a single mode optical fiber (SMF-28) in order to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments or to create a multi-cavity interferometric sensor. Spectral reflectance of films made from zinc oxide (ZnO), titanium dioxide (TiO2), aluminum oxide (Al2O3) and boron nitride (BN) was calculated for various thickness of the films and compared. The results show that the most promising materials for use in fiber-optic Fabry-Pérot interferometer are TiO2 and ZnO, although Al2O3 is also suitable for this application.

Electron-Selective TiO 2 Contact for Cu(In,Ga)Se 2 Solar Cells

DOE PAGES

Hsu, Weitse; Sutter-Fella, Carolin M.; Hettick, Mark; ...

2015-11-03

The non-toxic and wide bandgap material TiO 2 is explored as an n-type buffer layer on p-type Cu(In,Ga)Se 2 (CIGS) absorber layer for thin film solar cells. The amorphous TiO 2 thin film deposited by atomic layer deposition process at low temperatures shows conformal coverage on the CIGS absorber layer. Solar cells from non-vacuum deposited CIGS absorbers with TiO 2 buffer layer result in a high short-circuit current density of 38.9 mA/cm 2 as compared to 36.9 mA/cm 2 measured in the reference cell with CdS buffer layer, without compromising open-circuit voltage. The significant photocurrent gain, mainly in the UVmore » part of the spectrum, can be attributed to the low parasitic absorption loss in the ultrathin TiO 2 layer (~10 nm) with a larger bandgap of 3.4 eV compared to 2.4 eV of the traditionally used CdS. Overall the solar cell conversion efficiency was improved from 9.5% to 9.9% by substituting the CdS by TiO 2 on an active cell area of 10.5 mm2. In conclusion, optimized TiO 2/CIGS solar cells show excellent long-term stability. The results imply that TiO 2 is a promising buffer layer material for CIGS solar cells, avoiding the toxic CdS buffer layer with added performance advantage.« less

Influence of substrates and rutile seed layers on the assembly of hydrothermally grown rutile TiO2 nanorod arrays

NASA Astrophysics Data System (ADS)

Kalb, Julian; Dorman, James A.; Folger, Alena; Gerigk, Melanie; Knittel, Vanessa; Plüisch, Claudia S.; Trepka, Bastian; Lehr, Daniela; Chua, Emily; Goodge, Berit H.; Wittemann, Alexander; Scheu, Christina; Polarz, Sebastian; Schmidt-Mende, Lukas

2018-07-01

Rutile TiO2 nanorod arrays (NRAs) are applicable in various prospective technologies. Hydrothermal methods present a simple technique to fabricate such NRAs. In this report, we present the fabrication of seed layers for the hydrothermal growth of rutile TiO2 nanorods via sputter deposition, electron-beam evaporation, and sol-gel method and study the influence of each on the growth behavior. To satisfy the requirements of numerous applications, p-type silicon, platinum, levitating carbon membranes, a template made of polystyrene spheres, and commercial fluorine tin oxide (FTO) were employed as substrates. We document the structural properties of the TiO2 seed layers and describe the relationship between the characteristics of the seed crystals, the growth evolution, and the appearance of as-grown nanorods. Various growth stages of rutile TiO2 nanorods are compared depending on whether they are grown on polycrystalline TiO2 or FTO seed layers. In both cases, a homogenous TiO2 bottom layer is formed at the seed layer/substrate interface, which is essential for electronic applications such as hybrid solar cells. Detached NRAs illustrate the effect of rutile FTO and TiO2 on the porosity of this bottom layer. Further details about the formation process of this layer are obtained from the growth on confined seed layers fabricated by electron-beam lithography.

Study on preparation of SnO2-TiO2/Nano-graphite composite anode and electro-catalytic degradation of ceftriaxone sodium.

PubMed

Guo, Xiaolei; Wan, Jiafeng; Yu, Xiujuan; Lin, Yuhui

2016-12-01

In order to improve the electro-catalytic activity and catalytic reaction rate of graphite-like material, Tin dioxide-Titanium dioxide/Nano-graphite (SnO 2 -TiO 2 /Nano-G) composite was synthesized by a sol-gel method and SnO 2 -TiO 2 /Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy, fourier transform infrared, Raman, N 2 adsorption-desorption, scanning electrons microscopy, transmission electron microscopy and X-ray diffraction. The electrochemical performance of the SnO 2 -TiO 2 /Nano-G anode electrode was investigated via cyclic voltammetry and electrochemical impedance spectroscopy. The electro-catalytic performance was evaluated by the degradation of ceftriaxone sodium and the yield of ·OH radicals in the reaction system. The results demonstrated that TiO 2 , SnO 2 and Nano-G were composited successfully, and TiO 2 and SnO 2 particles dispersed on the surface and interlamination of the Nano-G uniformly. The specific surface area of SnO 2 modified anode was higher than that of TiO 2 /Nano-G anode and the degradation rate of ceftriaxone sodium within 120 min on SnO 2 -TiO 2 /Nano-G electrode was 98.7% at applied bias of 2.0 V. The highly efficient electro-chemical property of SnO 2 -TiO 2 /Nano-G electrode was attributed to the admirable conductive property of the Nano-G and SnO 2 -TiO 2 /Nano-G electrode. Moreover, the contribution of reactive species ·OH was detected, indicating the considerable electro-catalytic activity of SnO 2 -TiO 2 /Nano-G electrode. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Morphology of Titanium Dioxide Aerogels

NASA Astrophysics Data System (ADS)

Zhu, Zhu

The morphology of titanium dioxide TiO _2 aerogels has been characterized by four major techniques. This work will discuss these complementary techniques such as nitrogen adsorption, X-ray powder diffraction (XRD), electron microscopies (EM- TEM, SEM), and small angle neutron scattering (SANS). The results of these characterizations have shown that the morphology of titanium dioxide TiO_2 aerogels can be characterized in terms of two length scales: 5 nm diameter, crystalline nanoparticles of anatase closely packed into mesoaggregates about 50 nm in size. The mesoaggregates are, in turn, packed into a loosely linked structure with an overall porosity of 80%.

Synthesis and characterization of titanium dioxide (TiO2) nanopowder

NASA Astrophysics Data System (ADS)

Munirah, S.; Nadzirah, Sh.; Khusaimi, Z.; Fazlena, H.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) powder was synthesized via sol-gel technique using Titanium tetraisopropoxide (TTIP) and ethanol as precursors. Acetylacetone, distilled water, polyethylene glycol (PEG) and stabilizers (glacial acetic acid and nitric acid) were then added to the solution. The solution was left for ageing for 24 hours and then dried into powder. The synthesized powders were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA).

Nonactivated titanium-dioxide nanoparticles promote the growth of Chlamydia trachomatis and decrease the antimicrobial activity of silver nanoparticles.

PubMed

Bogdanov, A; Janovák, L; Lantos, I; Endrész, V; Sebők, D; Szabó, T; Dékány, I; Deák, J; Rázga, Z; Burián, K; Virok, D P

2017-11-01

Chlamydia trachomatis and herpes simplex virus (HSV) are the most prevalent bacterial and viral sexually transmitted infections. Due to the chronic nature of their infections, they are able to interact with titanium-dioxide (TiO 2 ) nanoparticles (NPs) applied as food additives or drug delivery vehicles. The aim of this study was to describe the interactions of these two prevalent pathogens with the TiO 2 NPs. Chlamydia trachomatis and HSV-2 were treated with nonactivated TiO 2 NPs, silver NPs and silver decorated TiO 2 NPs before infection of HeLa and Vero cells. Their intracellular growth was monitored by quantitative PCR. Unexpectedly, the TiO 2 NPs (100 μg ml -1 ) increased the growth of C. trachomatis by approximately fourfold, while the HSV-2 replication was not affected. Addition of TiO 2 to silver NPs decreased their antimicrobial activity against C. trachomatis up to 27·92-fold. In summary, nonactivated TiO 2 NPs could increase the replication of C. trachomatis and decrease the antimicrobial activity of silver NPs. The food industry or drug delivery use of TiO 2 NPs could enhance the growth of certain intracellular pathogens and potentially worsen disease symptoms, a feature that should be further investigated. © 2017 The Society for Applied Microbiology.

Effects of titanium dioxide nanoparticles derived from consumer products on the marine diatom Thalassiosira pseudonana

EPA Science Inventory

Increased manufacture of TiO2 nano-products has caused concern about the potential toxicity of these products to the environment and in public health. Identification and confirmation of the presence of TiO2 nanoparticles derived from consumer products as opposed to industrial TiO...

Photocytotoxicity in human dermal fibroblasts elicited by permanent makeup inks containing titanium dioxide.

PubMed

Wamer, Wayne G; Yin, Jun-Jie

2011-01-01

Titanium dioxide (TiO2) is a pigment widely used in decorative tattoo and permanent makeup inks. However, little is known about the risks associated with its presence in these products. We have developed an in vitro assay to identify inks containing TiO2 that are cytotoxic and/or photocytotoxic. The presence of TiO2 in ten permanent makeup inks was established by X-ray fluorescence. Using X-ray diffraction, we found that seven inks contained predominately TiO2 (anatase), the more photocatalytically active crystalline form of TiO2. The remaining inks contained predominately TiO2 (rutile). To identify cytotoxic and/or photocytotoxic inks, human dermal fibroblasts were incubated for 18 h in media containing inks or pigments isolated from inks. Fibroblasts were then irradiated with 10 J/cm2 UVA radiation combined with 45 J/cm2 visible light for determining photocytotoxicity, or kept in the dark for determining cytotoxicity. Toxicity was assessed as inhibition of colony formation. No inks were cytotoxic. However eight inks, and the pigments isolated from these inks, were photocytotoxic. Using ESR, we found that most pigments from photocytotoxic inks generated hydroxyl radicals when photoexcited with UV radiation. Therefore, the possibility of photocytotoxicity should be considered when evaluating the safety of permanent makeup inks containing TiO2.

Optimization of amino group density on surfaces of titanium dioxide nanoparticles covalently bonded to a silicone substrate for antibacterial and cell adhesion activities.

PubMed

Okada, Masahiro; Yasuda, Shoji; Kimura, Tsuyoshi; Iwasaki, Mitsunobu; Ito, Seishiro; Kishida, Akio; Furuzono, Tsutomu

2006-01-01

A composite consisting of titanium dioxide (TiO2) particle, the surface of which was modified with amino groups, and a silicone substrate through covalent bonding at their interface was developed, and antibacterial and cell adhesion activities of the composite were evaluated. The density of the amino groups on the TiO2 particle surface was controlled by the reaction time of the modification reaction. The degradation rate of CH3CHO in the presence of the TiO2 particles under UV irradiation decreased with an increase in the amino group density on the TiO2 surface. On the other hand, the number of L929 cells adhering on the TiO2/silicone composite increased with an increase in the amino group density. From the above two results, the optimum density of amino groups for both photoreactivity and cell adhesiveness was estimated to be 2.0-4.0 molecules/nm2. The optimum amino group-modified TiO2/silicone composite sheet (amino group density, 3.0 molecules/nm2) showed an effective antibacterial activity for Escherichia coli bacteria under UV irradiation. (c) 2005 Wiley Periodicals, Inc

Efficiency Enhancement of Nanotextured Black Silicon Solar Cells Using Al2O3/TiO2 Dual-Layer Passivation Stack Prepared by Atomic Layer Deposition.

PubMed

Wang, Wei-Cheng; Tsai, Meng-Chen; Yang, Jason; Hsu, Chuck; Chen, Miin-Jang

2015-05-20

In this study, efficient nanotextured black silicon (NBSi) solar cells composed of silicon nanowire arrays and an Al2O3/TiO2 dual-layer passivation stack on the n(+) emitter were fabricated. The highly conformal Al2O3 and TiO2 surface passivation layers were deposited on the high-aspect-ratio surface of the NBSi wafers using atomic layer deposition. Instead of the single Al2O3 passivation layer with a negative oxide charge density, the Al2O3/TiO2 dual-layer passivation stack treated with forming gas annealing provides a high positive oxide charge density and a low interfacial state density, which are essential for the effective field-effect and chemical passivation of the n(+) emitter. In addition, the Al2O3/TiO2 dual-layer passivation stack suppresses the total reflectance over a broad range of wavelengths (400-1000 nm). Therefore, with the Al2O3/TiO2 dual-layer passivation stack, the short-circuit current density and efficiency of the NBSi solar cell were increased by 11% and 20%, respectively. In conclusion, a high efficiency of 18.5% was achieved with the NBSi solar cells by using the n(+)-emitter/p-base structure passivated with the Al2O3/TiO2 stack.

Bactericidal effects and mechanisms of visible light-responsive titanium dioxide photocatalysts on pathogenic bacteria.

PubMed

Liou, Je-Wen; Chang, Hsin-Hou

2012-08-01

This review focuses on the antibacterial activities of visible light-responsive titanium dioxide (TiO(2)) photocatalysts. These photocatalysts have a range of applications including disinfection, air and water cleaning, deodorization, and pollution and environmental control. Titanium dioxide is a chemically stable and inert material, and can continuously exert antimicrobial effects when illuminated. The energy source could be solar light; therefore, TiO(2) photocatalysts are also useful in remote areas where electricity is insufficient. However, because of its large band gap for excitation, only biohazardous ultraviolet (UV) light irradiation can excite TiO(2), which limits its application in the living environment. To extend its application, impurity doping, through metal coating and controlled calcination, has successfully modified the substrates of TiO(2) to expand its absorption wavelengths to the visible light region. Previous studies have investigated the antibacterial abilities of visible light-responsive photocatalysts using the model bacteria Escherichia coli and human pathogens. The modified TiO(2) photocatalysts significantly reduced the numbers of surviving bacterial cells in response to visible light illumination. They also significantly reduced the activity of bacterial endospores; reducing their toxicity while retaining their germinating abilities. It is suggested that the photocatalytic killing mechanism initially damages the surfaces weak points of the bacterial cells, before totally breakage of the cell membranes. The internal bacterial components then leak from the cells through the damaged sites. Finally, the photocatalytic reaction oxidizes the cell debris. In summary, visible light-responsive TiO(2) photocatalysts are more convenient than the traditional UV light-responsive TiO(2) photocatalysts because they do not require harmful UV light irradiation to function. These photocatalysts, thus, provide a promising and feasible approach for disinfection of pathogenic bacteria; facilitating the prevention of infectious diseases.

Photocatalytic Activity of Nanotubular TiO2 Films Obtained by Anodic Oxidation: A Comparison in Gas and Liquid Phase

PubMed Central

Sanabria Arenas, Beatriz Eugenia; Schiavi, Luca; Russo, Valeria; Pedeferri, MariaPia

2018-01-01

The availability of immobilized nanostructured photocatalysts is of great importance in the purification of both polluted air and liquids (e.g., industrial wastewaters). Metal-supported titanium dioxide films with nanotubular morphology and good photocatalytic efficiency in both environments can be produced by anodic oxidation, which avoids release of nanoscale materials in the environment. Here we evaluate the effect of different anodizing procedures on the photocatalytic activity of TiO2 nanostructures in gas and liquid phases, in order to identify the most efficient and robust technique for the production of TiO2 layers with different morphologies and high photocatalytic activity in both phases. Rhodamine B and toluene were used as model pollutants in the two media, respectively. It was found that the role of the anodizing electrolyte is particularly crucial, as it provides substantial differences in the oxide specific surface area: nanotubular structures show remarkably different activities, especially in gas phase degradation reactions, and within nanotubular structures, those produced by organic electrolytes lead to better photocatalytic activity in both conditions tested. PMID:29587360

Effect of sintering temperatures and screen printing types on TiO2 layers in DSSC applications

NASA Astrophysics Data System (ADS)

Supriyanto, Agus; Furqoni, Lutfi; Nurosyid, Fahru; Hidayat, Jojo; Suryana, Risa

2016-03-01

Dye-Sensitized Solar Cell (DSSC) is a candidate solar cell, which has a big potential in the future due to its eco-friendly material. This research is conducted to study the effect of sintering temperature and the type of screen-printing toward the characteristics of TiO2 layer as a working electrode in DSSC. TiO2 layers were fabricated using a screen-printing method with a mesh size of T-49, T-55, and T-61. TiO2 layers were sintered at temperatures of 600°C and 650°C for 60 min. DSSC structure was composed of TiO2 as semiconductors, ruthenium complex as dyes, and carbon as counter electrodes. The morphology of TiO2 layer was observed by using Nikon E2 Digital Camera Microscopy. The efficiencies of DSSC were calculated from the I-V curves. The highest efficiency is 0.015% at TiO2 layer fabricated with screen type T-61 and at a sintering temperature of 650°C.

A mechanistic study to increase understanding of titanium dioxide nanoparticles-increased plasma glucose in mice.

PubMed

Hu, Hailong; Li, Li; Guo, Qian; Jin, Sanli; Zhou, Ying; Oh, Yuri; Feng, Yujie; Wu, Qiong; Gu, Ning

2016-09-01

Titanium dioxide nanoparticle (TiO2 NP) is an authorized food additive. Previous studies determined oral administration of TiO2 NPs increases plasma glucose in mice via inducing insulin resistance. An increase in reactive oxygen species (ROS) has been considered the possible mechanism of increasing plasma glucose. However, persistently high plasma glucose is also a mechanism of increasing ROS. This study aims to explore whether TiO2 NPs increase plasma glucose via ROS. We found after oral administration of TiO2 NPs, an increase in ROS preceded an increase in plasma glucose. Subsequently, mice were treated with two antioxidants (resveratrol and vitamin E) at the same time as oral administration of TiO2 NPs. Results showed resveratrol and vitamin E reduced TiO2 NPs-increased ROS. An increase in plasma glucose was also inhibited. Further research showed resveratrol and vitamin E inhibited the secretion of TNF-α and IL-6, and the phosphorylation of JNK and p38 MAPK, resulting in improved insulin resistance. These results suggest TiO2 NPs increased ROS levels, and then ROS activated inflammatory cytokines and phosphokinases, and thus induced insulin resistance, resulting in an increase in plasma glucose. Resveratrol and vitamin E can reduce TiO2 NPs-increased ROS and thereby inhibit an increase in plasma glucose in mice. Copyright © 2016 Elsevier Ltd. All rights reserved.

Charge-transfer complex formation between TiO2 nanoparticles and thiosalicylic acid: A comprehensive experimental and DFT study

NASA Astrophysics Data System (ADS)

Milićević, Bojana; Đorđević, Vesna; Lončarević, Davor; Dostanić, Jasmina M.; Ahrenkiel, S. Phillip; Dramićanin, Miroslav D.; Sredojević, Dušan; Švrakić, Nenad M.; Nedeljković, Jovan M.

2017-11-01

Under normal conditions, titanium dioxide does not absorb visible light photons due to large band gap. Nevertheless, when titanium dioxide nanoparticles (TiO2 NPs) are surface-modified with thiosalicylic acid (TSA), their optical properties are altered owing to the formation of charge transfer complex that initiates absorption in the visible spectral range. Colloidal and sol-gel techniques were used to synthesize uniform TiO2 NPs of different sizes (average diameters in the range 4-15 nm), and effects of their subsequent modification by TSA molecules were compared with effect of modification of commercial Degussa TiO2 powder. Thorough microstructural characterization of TiO2 nanoparticulates was performed including transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis, as well as nitrogen adsorption-desorption isotherms. Optical measurements revealed that all surface-modified TiO2 samples with TSA have similar spectral features independent of their morphological differences, and, more importantly, absorption onset of modified TiO2 samples was found to be red-shifted by 1.0 eV compared to the unmodified ones. The mode of binding between TSA and surface Ti atoms was analyzed by infrared spectroscopy. Finally, the quantum chemical calculations, based on density functional theory, were performed to support optical characterization of surface-modified TiO2 with TSA.

Effect of TiO 2 particle size and layer thickness on mesoscopic perovskite solar cells

DOE PAGES

Lee, Dong Geon; Kim, Min-cheol; Kim, Byeong Jo; ...

2017-11-16

Mesoporous TiO 2 (mp-TiO 2) layers are commonly used as electron transport layers in perovskite solar cells, which help to extract electrons from the perovskite light-absorbing layer and transport them to the electrodes. We investigated the effects of the layer thickness of mp-TiO 2 and particle size of TiO 2 on photovoltaic properties, in terms of the surface area of the mp-layer and the interfacial areas of the TiO 2 nanoparticles in the mp-layer. Various mp-TiO 2 layers with thicknesses of 150, 250, and 400 nm and particle sizes of 25 nm and 41 nm were prepared to compare themore » photovoltaic properties of such layer-containing perovskite solar cells. Time-resolved photoluminescence decay and impedance studies showed that interfacial resistance as well as perovskite-to-TiO 2 charge injection are important factors affecting photovoltaic performance. The deterioration of the photovoltaic parameters with increasing TiO 2/TiO 2 interfacial area also confirms that the interfacial series resistance that arises from these connections should be reduced to enhance the performance of mesoscopic perovskite solar cells.« less

Effect of TiO 2 particle size and layer thickness on mesoscopic perovskite solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dong Geon; Kim, Min-cheol; Kim, Byeong Jo

Mesoporous TiO 2 (mp-TiO 2) layers are commonly used as electron transport layers in perovskite solar cells, which help to extract electrons from the perovskite light-absorbing layer and transport them to the electrodes. We investigated the effects of the layer thickness of mp-TiO 2 and particle size of TiO 2 on photovoltaic properties, in terms of the surface area of the mp-layer and the interfacial areas of the TiO 2 nanoparticles in the mp-layer. Various mp-TiO 2 layers with thicknesses of 150, 250, and 400 nm and particle sizes of 25 nm and 41 nm were prepared to compare themore » photovoltaic properties of such layer-containing perovskite solar cells. Time-resolved photoluminescence decay and impedance studies showed that interfacial resistance as well as perovskite-to-TiO 2 charge injection are important factors affecting photovoltaic performance. The deterioration of the photovoltaic parameters with increasing TiO 2/TiO 2 interfacial area also confirms that the interfacial series resistance that arises from these connections should be reduced to enhance the performance of mesoscopic perovskite solar cells.« less

Atomic layer deposition of nano-TiO2 thin films with enhanced biocompatibility and antimicrobial activity for orthopedic implants

PubMed Central

Liu, Luting; Bhatia, Ritwik; Webster, Thomas J

2017-01-01

Titanium (Ti) and its alloys have been extensively used as implant materials in orthopedic applications. Nevertheless, implants may fail due to a lack of osseointegration and/or infection. The aim of this in vitro study was to endow an implant surface with favorable biological properties by the dual modification of surface chemistry and nanostructured topography. The application of a nanostructured titanium dioxide (TiO2) coating on Ti-based implants has been proposed as a potential way to enhance tissue-implant interactions while inhibiting bacterial colonization simultaneously due to its chemical stability, biocompatibility, and antimicrobial properties. In this paper, temperature-controlled atomic layer deposition (ALD) was introduced for the first time to provide unique nanostructured TiO2 coatings on Ti substrates. The effect of nano-TiO2 coatings with different morphology and structure on human osteoblast and fibroblast functions and bacterial activities was investigated. In vitro results indicated that the TiO2 coating stimulated osteoblast adhesion and proliferation while suppressing fibroblast adhesion and proliferation compared to uncoated materials. In addition, the introduction of nano-TiO2 coatings was shown to inhibit gram-positive bacteria (Staphylococcus aureus), gram-negative bacteria (Escherichia coli), and antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus), all without resorting to the use of antibiotics. Our results suggest that the increase in nanoscale roughness and greater surface hydrophilicity (surface energy) together could contribute to increased protein adsorption selectively, which may affect the cellular and bacterial activities. It was found that ALD-grown TiO2-coated samples with a moderate surface energy at 38.79 mJ/m2 showed relatively promising antibacterial properties and desirable cellular functions. The ALD technique provides a novel and effective strategy to produce TiO2 coatings with delicate control of surface nanotopography and surface energy to enhance the interfacial biocompatibility and mitigate bacterial infection, and could potentially be used for improving numerous orthopedic implants. PMID:29263665

Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation.

PubMed

Kato, Yoshiteru; Nakashima, Yasuhiko; Shino, Naoki; Sasaki, Koichi; Hosokawa, Akihiro; Ishihara, Hiroshi

2010-04-01

The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm. Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy. In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2). It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.

Synthesis, characterization, and photocatalytic properties of core/shell mesoporous silica nanospheres supporting nanocrystalline titania

NASA Astrophysics Data System (ADS)

Cendrowski, K.; Chen, X.; Zielinska, B.; Kalenczuk, R. J.; Rümmeli, M. H.; Büchner, B.; Klingeler, R.; Borowiak-Palen, E.

2011-11-01

The facile bulk synthesis of silica nanospheres makes them an attractive support for the transport of chemical compounds such as nanocrystalline titanium dioxide. In this contribution we present a promising route for the synthesis of mesoporous silica nanospheres (m-SiO2) with diameter in range 200 nm, which are ideal supports for nanocrystalline titanium dioxide (TiO2). The detailed microscopic and spectroscopic characterizations of core/shell structure (m-SiO2/TiO2) were conducted. Moreover, the photocatalytic potential of the nanostructures was investigated via phenol decomposition and hydrogen generation. A clear enhancement of photoactivity in both reactions as compared to commercial TiO2-Degussa P25 catalyst is detected.

Preparation and characterization of nanostructured Pt/TiO2 thin films treated using electron beam.

PubMed

Shin, Joong-Hyeok; Woo, Hee-Gweon; Kim, Bo-Hye; Lee, Byung Cheol; Jun, Jin

2010-05-01

Pt nanoparticle-doped titanium dioxide (Pt/TiO2) thin films were prepared on a silicon wafer substrate by sol-gel spin coating process. The prepared thin films were treated with electron beam (EB at 1.1 MeV, 100, 200, 300 kGy) at air atmosphere. The effect of EB-irradiation on the composition of the treated thin films, optical properties and morphology of thin films were investigated by various analytical techniques such as X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The crystal structure of the TiO2 layer was found to be an anatase phase and the size of TiO2 particles was determined to be about 13 nm. Pt nanoparticles with diameter of 5 nm were observed on surface of the films. A new layer (presumed to be Pt-Ti complex and/or PtO2 compound) was created in the Pt/TiO2 thin film treated with EB (300 kGy). The transmittance of thin film decreased with EB treatment whereas the refractive index increased.

Titanium Dioxide Coating Prepared by Use of a Suspension-Solution Plasma-Spray Process

NASA Astrophysics Data System (ADS)

Du, Lingzhong; Coyle, Thomas W.; Chien, Ken; Pershin, Larry; Li, Tiegang; Golozar, Mehdi

2015-08-01

Titanium dioxide coatings were prepared from titanium isopropoxide solution containing nano TiO2 particles by use of a plasma-spray process. The effects of stand-off distance on coating composition and microstructure were investigated and compared with those for pure solution precursor and a water-based suspension of TiO2. The results showed that the anatase content of the coating increased with increasing stand-off distance and the rate of deposition decreased with increasing spray distance. Anatase nanoparticles in solution were incorporated into the coatings without phase transformation whereas most of the TiO2 in the precursor solution was transformed into rutile. The microstructure of preserved anatase particles bound by rutile improved the efficiency of deposition of the coating. The amount of anatase phase can be adjusted by variation of the ratio of solution to added anatase TiO2 nanoparticles.

Dermal Titanium Dioxide Deposition Associated With Intralesional Triamcinolone Injection.

PubMed

Cohen, Brandon E; Bashey, Sameer; Cole, Christine; Abraham, Jerrold L; Ragsdale, Bruce; Ngo, Binh

2016-12-01

Cutaneous discoloration secondary to dermal deposition of titanium dioxide (TiO2) particles is recognized but seldom reported in the literature. In this report, the authors describe the case of a 61-year-old gentleman, with a long history of alopecia areata, who presented with numerous, discrete dark blue macules on the scalp. Scanning electron microscopy with energy dispersive x-ray spectroscopy analysis ultimately identified the macules as deposits of TiO2. The patient had a history of intralesional triamcinolone injections for management of alopecia areata. A sample of generic 0.1% triamcinolone acetonide paste was analyzed and found to contain many TiO2 particles analogous to those seen in the patient's biopsy sample. To the authors' knowledge, this is the first reported case of TiO2 deposition in the dermis likely resulting from topical combined with intralesional triamcinolone injection.

Sunscreens with Titanium Dioxide (TiO2) Nano-Particles: A Societal Experiment

PubMed Central

van de Poel, Ibo; Osseweijer, Patricia

2010-01-01

The risks of novel technologies, such as nano(bio)technology cannot be fully assessed due to the existing uncertainties surrounding their introduction into society. Consequently, the introduction of innovative technologies can be conceptualised as a societal experiment, which is a helpful approach to evaluate moral acceptability. This approach is illustrated with the marketing of sunscreens containing nano-sized titanium dioxide (TiO2) particles. We argue that the marketing of this TiO2 nanomaterial in UV protective cosmetics is ethically undesirable, since it violates four reasonable moral conditions for societal experimentation (absence of alternatives, controllability, limited informed consent, and continuing evaluation). To remedy the current way nano-sized TiO2 containing sunscreens are utilised, we suggest five complementing actions (closing the gap, setup monitoring tools, continuing review, designing for safety, and regulative improvements) so that its marketing can become more acceptable. PMID:20835397

The photovoltaic efficiency of the fabrication of copolymer P3HT:PCBM on different thickness nano-anatase titania as solar cell.

PubMed

Lazim, Haidar Gazy; Ajeel, Khalid I; Badran, Hussain A

2015-06-15

Organic solar cells based on (3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM) bulk heterojunction (BHJ) with an inverted structure have been fabricated using nano-anatase crystalline titanium dioxide (TiO2) as their electron transport layer, which was prepared on the indium tin oxide coated glass (ITO-glass), silicon wafer and glass substrates by sol-gel method at different spin speed by using spin-coating (1000, 2000 and 3,000 rpm) for nano-thin film 58, 75 and 90 nm respectively. The effect of thickness on the surface morphology and optical properties of TiO2 layer were investigated by atomic force microscopy (AFM), X-ray diffraction and UV-visible spectrophotometer. The optical band gap of the films has been found to be in the range 3.63-3.96 eV for allowed direct transition and to be in the range 3.23-3.69 eV for forbidden direct transition to the different TiO2 thickness. The samples were examined to feature current and voltages darkness and light extraction efficiency of the solar cell where they were getting the highest open-circuit voltage, Voc, and power conversion efficiency were 0.66% and 0.39% fabricated with 90 nm respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of preparation methods on the activity of titanium dioxide-carbon nitride composites for photocatalytic degradation of salicylic acid

NASA Astrophysics Data System (ADS)

Yuliati, L.; Salleh, A. M.; Hatta, M. H. M.; Lintang, H. O.

2018-04-01

In this study, titanium dioxide-carbon nitride (TiO2-CN) composites were prepared by three methods, which were one pot oxidation, impregnation, and physical mixing. Each series of the photocatalysts was prepared with different ratios of titanium to carbon (Ti/C), i.e., 1, 5, 10, 20, and 50 mol%. All samples were characterized by X-ray diffraction (XRD) and diffuse reflectance ultraviolet-visible (DR UV-Vis) spectroscopies. The characterization results confirmed the successful preparation of TiO2, CN, and the TiO2-CN composites. Photocatalytic activity tests were carried out for degradation of salicylic acid at room temperature for 6 h under UV and visible light irradiations. It was confirmed that all the prepared TiO2-CN composites showed better photocatalytic activities than the bare TiO2 and the bare CN. Under UV light irradiation, 90.6% of salicylic acid degradation was achieved on the best composite prepared by one pot oxidation with 5 mol% of titanium to carbon (Ti/C) ratio. On the other hand, the highest degradation under visible light irradiation was 94.3%, observed on the composite that was prepared also by one pot oxidation method with the Ti/C ratio of 10 mol%. Therefore, among the investigated methods, the best method to prepare the titanium dioxide-carbon nitride composites with high photocatalytic activity was one pot oxidation method.

Rutile titanium dioxide films deposited with a vacuum arc at different temperatures

NASA Astrophysics Data System (ADS)

Arias, L. Franco; Kleiman, A.; Heredia, E.; Márquez, A.

2012-06-01

Rutile crystalline phase of TiO2 has been one of the most investigated materials for medical applications. Its implementation as a surface layer on biomedical implants has shown to improve hemocompatibility and biocompatibility. In this work, titanium dioxide coatings were deposited on glass and steel 316L substrates using cathodic arc deposition. The coatings were obtained at different substrate temperatures; varying from room temperature to 600°C. The crystalline structure of the films was identified by glancing angle X-ray diffraction. Depending on the substrate material and on its temperature during the deposition process, anatase, anatse+rutile and rutile structures were observed. It was determined that rutile films can be obtained below 600 °C with this deposition method.

Titanium dioxide nanoparticles alter cellular morphology via disturbing the microtubule dynamics

NASA Astrophysics Data System (ADS)

Mao, Zhilei; Xu, Bo; Ji, Xiaoli; Zhou, Kun; Zhang, Xuemei; Chen, Minjian; Han, Xiumei; Tang, Qiusha; Wang, Xinru; Xia, Yankai

2015-04-01

Titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in our daily lives, for example, in the areas of sunscreens, cosmetics, toothpastes, food products, and nanomedical reagents. Recently, increasing concern has been raised about their neurotoxicity, but the mechanisms underlying such toxic effects are still unknown. In this work, we employed a human neuroblastoma cell line (SH-SY5Y) to study the effects of TiO2 NPs on neurological systems. Our results showed that TiO2 NPs did not affect cell viability but induced noticeable morphological changes until 100 μg ml-1. Immunofluorescence detection showed disorder, disruption, retraction, and decreased intensity of the microtubules after TiO2 NPs treatment. Both α and β tubule expressions did not change in the TiO2 NP-treated group, but the percentage of soluble tubules was increased. A microtubule dynamic study in living cells indicated that TiO2 NPs caused a lower growth rate and a higher shortening rate of microtubules as well as shortened lifetimes of de novo microtubules. TiO2 NPs did not cause changes in the expression and phosphorylation state of tau proteins, but a tau-TiO2 NP interaction was observed. TiO2 NPs could interact with tubule heterodimers, microtubules and tau proteins, which led to the instability of microtubules, thus contributing to the neurotoxicity of TiO2 NPs.Titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in our daily lives, for example, in the areas of sunscreens, cosmetics, toothpastes, food products, and nanomedical reagents. Recently, increasing concern has been raised about their neurotoxicity, but the mechanisms underlying such toxic effects are still unknown. In this work, we employed a human neuroblastoma cell line (SH-SY5Y) to study the effects of TiO2 NPs on neurological systems. Our results showed that TiO2 NPs did not affect cell viability but induced noticeable morphological changes until 100 μg ml-1. Immunofluorescence detection showed disorder, disruption, retraction, and decreased intensity of the microtubules after TiO2 NPs treatment. Both α and β tubule expressions did not change in the TiO2 NP-treated group, but the percentage of soluble tubules was increased. A microtubule dynamic study in living cells indicated that TiO2 NPs caused a lower growth rate and a higher shortening rate of microtubules as well as shortened lifetimes of de novo microtubules. TiO2 NPs did not cause changes in the expression and phosphorylation state of tau proteins, but a tau-TiO2 NP interaction was observed. TiO2 NPs could interact with tubule heterodimers, microtubules and tau proteins, which led to the instability of microtubules, thus contributing to the neurotoxicity of TiO2 NPs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01448d

Effect of TiO2 addition on surface microstructure and bioactivity of fluorapatite coatings deposited using Nd:YAG laser.

PubMed

Chien, Chi-Sheng; Ko, Yu-Sheng; Kuo, Tsung-Yuan; Liao, Tze-Yuan; Lee, Tzer-Min; Hong, Ting-Fu

2014-04-01

To study the effect of titania (TiO2) addition on the surface microstructure and bioactivity of fluorapatite coatings, fluorapatite was mixed with TiO2 in 1:0.5 (FA + 0.5TiO2), 1:0.8 (FA + 0.8TiO2), and 1:1 (FA + TiO2) ratios (wt%) and clad on Ti-6Al-4V substrates using an Nd:YAG laser system. The experimental results show that the penetration depth of the weld decreases with increasing TiO2 content. Moreover, the subgrain structure of the coating layer changes from a fine cellular-like structure to a cellular-dendrite-like structure as the amount of TiO2 increases. Consequently, as the proportion of TiO2 decreases (increase in fluorapatite content), the Ca/P ratio of the coating layer also decreases. The immersion of specimens into simulated body fluid resulted in the formation of individual apatite. With a lower Ca/P ratio before immersion, the growth of the apatite was faster and then the coating layer provided a better bioactivity. X-ray diffraction analysis results show that prior to simulated body fluid immersion, the coating layer in all three specimens was composed mainly of fluorapatite, CaTiO3, and Al2O3 phases. Following simulated body fluid immersion, a peak corresponding to hydroxycarbonated apatite appeared after 2 days in the FA + 0.5TiO2 and FA + 0.8TiO2 specimens and after 7 days in the FA + TiO2 specimen. Overall, the results show that although the bioactivity of the coating layer tended to decrease with increasing TiO2 content, in accordance with the above-mentioned ratios, the bioactivity of all three specimens remained generally good.

Printable Integrated Photonic Devices

DTIC Science & Technology

2016-06-16

titanium dioxide ( TiO2 ), having n>2 and an excellent optical transmission (>90%) down to 400 nm wavelength. We developed a hybrid organic-inorganic...1) Figure 1: aBeam’s proprietary TiO2 (ceramic) based high-refractive index imprint material (a) refractive index vs. wavelength, and (b...nanocrystals were synthesized and incorporated into the sol-gel precursor. TiO2 based imprint materials typically require high annealing temperature at

Synthesis of TiO2 Nanoparticle and its phase Transition

NASA Astrophysics Data System (ADS)

Mangrola, M. H.; Joshi, V. G.; Parmar, B. H.

2011-12-01

Here we report the synthesis of titanium dioxide (TiO2) nanoparticles and study of its phase transition from anataze to rutile. Titanium dioxide (TiO2) nanoparticles have been prepared by hydrolysis of Titanium isopropoxide an aqueous solution with constant value of pH 2 and peptizing the resultant suspension gel(white-Blue) and calcinate gel at different temperature. Structures of synthetic samples of TiO2 have been examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). The anatase-rutile transition has been a popular topic due to its interest to scientific and engineering fields. . Here we have seen that the 100 °C calcinate powder consist of anatase fine crystalline phase with a particle size 14 to 15 nm. The prepared TiO2 nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks. The phase transform occurred from anatase to rutile at calcinate temperature up to 600 °C. A very fine network texture made from uniform nanoparticles was revealed by scanning electron microscopy (SEM) analyses.

Photocatalytic dye degradation with copper-titanium dioxide nanocomposites under sunlight and visible light irradiation

NASA Astrophysics Data System (ADS)

Qayyum Khan, Abdul; Yuan, Shuai; Niu, Sheng; Liu, Fengjiang; Feng, Guang; Jiang, Mengci; Zeng, Heping

2018-01-01

Photocatalytic methalyne blue dye degradation was carried out with copper (Cu)-titanium dioxide (TiO2) nanocomposites under sunlight and visible light irradiation. The Cu-TiO2 nanocomposites were fabricated via femtosecond laser ablation of pressed targets in water. The current method provides a facile route for Cu-TiO2 nanocomposites preparation, which is free from impurities on the catalysts surface. The Cu-TiO2 nanocomposites (with Cu content of 5 wt%) have shown 3 folds faster dye degradation kinetics compared with TiO2 nanoparticles under sunlight irradiation. While under visible light irradiation, the same nanocomposites exhibited 2.6 folds faster kinetics compared with TiO2 nanoparticles. The faster light harvesting efficiency of the catalysts is attributed to more hydroxyl radical generation.

SYNTHESIZING ORGANIC COMPOUNDS USING LIGHT-ACTIVATED TIO2

EPA Science Inventory

High-value organic compounds have been synthesized successfully from linear and cyclic hydrocarbons, by photocatalytic oxidation using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxgenated in both liquid and gaseous phase reactors usi...

Effects of human food grade titanium dioxide nanoparticle dietary exposure on Drosophila melanogaster survival, fecundity, pupation and expression of antioxidant genes.

PubMed

Jovanović, Boris; Cvetković, Vladimir J; Mitrović, Tatjana Lj

2016-02-01

The fruitfly, Drosophila melanogaster was exposed to the human food grade of E171 titanium dioxide (TiO2). This is a special grade of TiO2 which is frequently omitted in nanotoxicology studies dealing with TiO2, yet it is the most relevant grade regarding oral exposure of humans. D. melanogaster larvae were exposed to 0.002 mg mL(-1), 0.02 mg mL(-1), 0.2 mg mL(-1), and 2 mg mL(-1) of TiO2 in feeding medium, and the survival, fecundity, pupation time, and expression of genes involved in oxidative stress response were monitored. TiO2 did not affect survival but significantly increased time to pupation (p < 0.001). Fecundity of D. melanogaster was unaffected by the treatment. Expression of the gene for catalase was markedly downregulated by the treatment, while the effect on the downregulation of superoxide dismutase 2 was less pronounced. After four days of dietary exposure TiO2 was present in a significant amount in larvae, but was not transferred to adults during metamorphosis. Two individuals with aberrant phenotype similar to previously described gold nanoparticles induced mutant phenotypes were detected in the group exposed to TiO2. In general, TiO2 showed little toxicity toward D. melanogaster at concentrations relevant to oral exposure of humans. Copyright © 2015 Elsevier Ltd. All rights reserved.

Whiter, brighter, and more stable cellulose paper coated with TiO2 /SiO2 core/shell nanoparticles using a layer-by-layer approach.

PubMed

Cheng, Fei; Lorch, Mark; Sajedin, Seyed Mani; Kelly, Stephen M; Kornherr, Andreas

2013-08-01

To inhibit the photocatalytic degradation of organic material supports induced by small titania (TiO2 ) nanoparticles, four kinds of TiO2 nanoparticles, that is, commercial P25-TiO2 , commercial rutile phase TiO2 , rutile TiO2 nanorods and rutile TiO2 spheres, prepared from TiCl4 , were coated with a thin, but dense, coating of silica (SiO2 ) using a conventional sol-gel technique to form TiO2 /SiO2 core/shell nanoparticles. These core/shell particles were deposited and fixed as a very thin coating onto the surface of cellulose paper samples by a wet-chemistry polyelectrolyte layer-by-layer approach. The TiO2 /SiO2 nanocoated paper samples exhibit higher whiteness and brightness and greater stability to UV-bleaching than comparable samples of blank paper. There are many potential applications for this green chemistry approach to protect cellulosic fibres from UV-bleaching in sunlight and to improve their whiteness and brightness. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of Film Thickness of Ultrathin Dip-Coated Compact TiO2 Layers on the Performance of Mesoscopic Perovskite Solar Cells.

PubMed

Masood, Muhammad Talha; Weinberger, Christian; Sarfraz, Jawad; Rosqvist, Emil; Sandén, Simon; Sandberg, Oskar J; Vivo, Paola; Hashmi, Ghufran; Lund, Peter D; Österbacka, Ronald; Smått, Jan-Henrik

2017-05-31

Uniform and pinhole-free electron-selective TiO 2 layers are of utmost importance for efficient perovskite solar cells. Here we used a scalable and low-cost dip-coating method to prepare uniform and ultrathin (5-50 nm) compact TiO 2 films on fluorine-doped tin oxide (FTO) glass substrates. The thickness of the film was tuned by changing the TiCl 4 precursor concentration. The formed TiO 2 follows the texture of the underlying FTO substrates, but at higher TiCl 4 concentrations, the surface roughness is substantially decreased. This change occurs at a film thickness close to 20-30 nm. A similar TiCl 4 concentration is needed to produce crystalline TiO 2 films. Furthermore, below this film thickness, the underlying FTO might be exposed resulting in pinholes in the compact TiO 2 layer. When integrated into mesoscopic perovskite solar cells there appears to be a similar critical compact TiO 2 layer thickness above which the devices perform more optimally. The power conversion efficiency was improved by more than 50% (from 5.5% to ∼8.6%) when inserting a compact TiO 2 layer. Devices without or with very thin compact TiO 2 layers display J-V curves with an "s-shaped" feature in the negative voltage range, which could be attributed to immobilized negative ions at the electron-extracting interface. A strong correlation between the magnitude of the s-shaped feature and the exposed FTO seen in the X-ray photoelectron spectroscopy measurements indicates that the s-shape is related to pinholes in the compact TiO 2 layer when it is too thin.

Tunable top-down fabrication and functional surface coating of single-crystal titanium dioxide nanostructures and nanoparticles

NASA Astrophysics Data System (ADS)

Ha, Seungkyu; Janissen, Richard; Ussembayev, Yera Ye.; van Oene, Maarten M.; Solano, Belen; Dekker, Nynke H.

2016-05-01

Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and yet-to-be-developed applications. However, the implementation of single-crystal TiO2 has been hampered by challenges in its fabrication and subsequent surface functionalization. Here, we introduce a novel top-down approach that allows for batch fabrication of uniform high-aspect-ratio single-crystal TiO2 nanostructures with targeted sidewall profiles. We complement our fabrication approach with a functionalization strategy that achieves dense, uniform, and area-selective coating with a variety of biomolecules. This allows us to fabricate single-crystal rutile TiO2 nanocylinders tethered with individual DNA molecules for use as force- and torque-transducers in an optical torque wrench. These developments provide the means for increased exploitation of the superior material properties of single-crystal TiO2 at the nanoscale.Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and yet-to-be-developed applications. However, the implementation of single-crystal TiO2 has been hampered by challenges in its fabrication and subsequent surface functionalization. Here, we introduce a novel top-down approach that allows for batch fabrication of uniform high-aspect-ratio single-crystal TiO2 nanostructures with targeted sidewall profiles. We complement our fabrication approach with a functionalization strategy that achieves dense, uniform, and area-selective coating with a variety of biomolecules. This allows us to fabricate single-crystal rutile TiO2 nanocylinders tethered with individual DNA molecules for use as force- and torque-transducers in an optical torque wrench. These developments provide the means for increased exploitation of the superior material properties of single-crystal TiO2 at the nanoscale. Electronic supplementary information (ESI) available: Experimental details (ESI Methods) of the optic axis orientation of TiO2 nanocylinders, Cr etch mask fabrication, surface functionalization and its evaluation using fluorescence microscopy, preparation of DNA constructs, assembly of flow cells, bioconjugation of TiO2 nanocylinders, OTW instrumentation and measurements; TiO2 dry etching optimization and the etching parameters employed (Tables S1 and S2); dimensional analysis of TiO2 nanocylinders (Table S3); diverse applications of TiO2 at the nanoscale (Fig. S1); selection of etch mask material (Fig. S2); control of sidewall profiles in TiO2 etching (Fig. S3); size distributions of TiO2 nanocylinders (Fig. S4); quantitative comparisons of different surface linker molecules (Fig. S5); DLS measurements on TiO2 nanocylinders (Fig. S6); optical trap calibration (Fig. S7); and supplementary references. See DOI: 10.1039/c6nr00898d

Nanostructured Gd3+-TiO2 surfaces for self-cleaning application

NASA Astrophysics Data System (ADS)

Saif, M.; El-Molla, S. A.; Aboul-Fotouh, S. M. K.; Ibrahim, M. M.; Ismail, L. F. M.; Dahn, Douglas C.

2014-06-01

Preparation of self-cleaning surfaces based on lanthanide modified titanium dioxide nanoparticles has rarely been reported. In the present work, gadolinium doped titanium dioxide thin films (x mol Gd3+-TiO2 where x = 0.000, 0.005, 0.008, 0.010, 0.020 and 0.030 mol) were synthesized by sol-gel method and deposited using doctor-blade method. These films were characterized by studying their structural, optical and electrical properties. Doping with gadolinium decreases the band gap energy and increase conductivity of thin films. The photo self-cleaning activity in term of quantitative determination of the active oxidative species (rad OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results show that, the highly active thin film is the 0.020 Gd3+-TiO2. The structural, morphology, optical, electrical and photoactivity properties of Gd3+-TiO2 thin films make it promising surfaces for self-cleaning application. Mineralization of commercial textile dye (Remazol Red RB-133, RR) and durability using 0.020Gd3+-TiO2 film surface was studied.

Shape-Related Toxicity of Titanium Dioxide Nanofibres

PubMed Central

Allegri, Manfredi; Bianchi, Massimiliano G.; Chiu, Martina; Varet, Julia; Costa, Anna L.; Ortelli, Simona; Blosi, Magda; Bussolati, Ovidio; Poland, Craig A.; Bergamaschi, Enrico

2016-01-01

Titanium dioxide (TiO2) nanofibres are a novel fibrous nanomaterial with increasing applications in a variety of fields. While the biological effects of TiO2 nanoparticles have been extensively studied, the toxicological characterization of TiO2 nanofibres is far from being complete. In this study, we evaluated the toxicity of commercially available anatase TiO2 nanofibres using TiO2 nanoparticles (NP) and crocidolite asbestos as non-fibrous or fibrous benchmark materials. The evaluated endpoints were cell viability, haemolysis, macrophage activation, trans-epithelial electrical resistance (an indicator of the epithelial barrier competence), ROS production and oxidative stress as well as the morphology of exposed cells. The results showed that TiO2 nanofibres caused a cell-specific, dose-dependent decrease of cell viability, with larger effects on alveolar epithelial cells than on macrophages. The observed effects were comparable to those of crocidolite, while TiO2 NP did not decrease cell viability. TiO2 nanofibres were also found endowed with a marked haemolytic activity, at levels significantly higher than those observed with TiO2 nanoparticles or crocidolite. Moreover, TiO2 nanofibres and crocidolite, but not TiO2 nanoparticles, caused a significant decrease of the trans-epithelial electrical resistance of airway cell monolayers. SEM images demonstrated that the interaction with nanofibres and crocidolite caused cell shape perturbation with the longest fibres incompletely or not phagocytosed. The expression of several pro-inflammatory markers, such as NO production and the induction of Nos2 and Ptgs2, was significantly increased by TiO2 nanofibres, as well as by TiO2 nanoparticles and crocidolite. This study indicates that TiO2 nanofibres had significant toxic effects and, for most endpoints with the exception of pro-inflammatory changes, are more bio-active than TiO2 nanoparticles, showing the relevance of shape in determining the toxicity of nanomaterials. Given that several toxic effects of TiO2 nanofibres appear comparable to those observed with crocidolite, the possibility that they exert length dependent toxicity in vivo seems worthy of further investigation. PMID:26999274

Toxicity and Fate Comparison between Several Brass and Titanium Dioxide Powders

DTIC Science & Technology

1993-07-01

the entire gut without showing any apparent effects . 14. UBJET TEMS1I. NUMBER OF PAGES 27 Daphnia Algae EC50 Aquatic toxicity 11T.PRICE CODE 9...levels of soluble copper and zinc in solution. 3. RESULTS The titanium dioxide ( TiO2 ) materials did not show any apparent toxic effects to daphnia up to...The extended exposure did not show any apparent toxic effects . Long term effects on aquatic org.rnisms exposed to TiO2 are not known. It is apparent

Three Dimensional Reconstruction Algorithm for Imaging Pathophysiological Signals Within Breast Tissue Using Near Infrared Light

DTIC Science & Technology

2006-07-01

months.31 A heated mixture of water, gelatin (G2625, Sigma Inc.), India ink (for absorption), and titanium dioxide powder (for scatter) (TiO2, Sigma Inc...for absorption, and titanium dioxide powder for scat- ter TiO2, Sigma Inc. that are solidified by cooling to room temperature. Optically...2713-2727. 8. Bolin, F.P., Preuss, L. E., Taylor, R. C., Ference, R. J, Refractive index of some mammalian tissue using a fiber optic cladding method

Food grade titanium dioxide disrupts intestinal brush border microvilli in vitro independent of sedimentation.

PubMed

Faust, James J; Doudrick, Kyle; Yang, Yu; Westerhoff, Paul; Capco, David G

2014-06-01

Bulk- and nano-scale titanium dioxide (TiO2) has found use in human food products for controlling color, texture, and moisture. Once ingested, and because of their small size, nano-scale TiO2 can interact with a number of epithelia that line the human gastrointestinal tract. One such epithelium responsible for nutrient absorption is the small intestine, whose constituent cells contain microvilli to increase the total surface area of the gut. Using a combination of scanning and transmission electron microscopy it was found that food grade TiO2 (E171 food additive coded) included ∼25% of the TiO2 as nanoparticles (NPs; <100 nm), and disrupted the normal organization of the microvilli as a consequence of TiO2 sedimentation. It was found that TiO2 isolated from the candy coating of chewing gum and a commercially available TiO2 food grade additive samples were of the anatase crystal structure. Exposure to food grade TiO2 additives, containing nanoparticles, at the lowest concentration tested within this experimental paradigm to date at 350 ng/mL (i.e., 100 ng/cm(2) cell surface area) resulted in disruption of the brush border. Through the use of two independent techniques to remove the effects of gravity, and subsequent TiO2 sedimentation, it was found that disruption of the microvilli was independent of sedimentation. These data indicate that food grade TiO2 exposure resulted in the loss of microvilli from the Caco-2BBe1 cell system due to a biological response, and not simply a physical artifact of in vitro exposure.

Influence of titanium dioxide nanoparticles on cadmium and lead bioaccumulations and toxicities to Daphnia magna

NASA Astrophysics Data System (ADS)

Li, Ling; Sillanpää, Markus; Schultz, Eija

2017-06-01

Titanium dioxide nanoparticles (TiO2 NPs) have attracted considerable concerns due to the increasing production and widespread applications, while their influences on other co-existing pollutants in real environment are not well studied. In this paper, the colloidal stability of TiO2 NPs in the exposure medium was first evaluated, and then, the medium was modified so that TiO2 NP suspension remained stable over the exposure period. Finally, using the optimized exposure medium, the effects of cadmium (Cd) and lead (Pb) on Daphnia magna both in the absence and presence of TiO2 NPs were investigated. Results showed that 2 mg L-1 of TiO2 NPs was well dispersed in 1:20 diluted Elendt M7 medium without EDTA, and no immobility was observed. The presence of the nanoparticles increased the bioaccumulation and toxicity of Cd to the daphnias. On the contrary, while Pb bioaccumulation was enhanced by three to four times, toxicity of Pb was reduced in the presence of TiO2 NPs. The decreased toxicity of Pb was more likely attributed to the decreased bioavailability of free Pb ion due to adsorption and speciation change of Pb in the presence of TiO2 NPs. Additionally, surface-attached TiO2 NPs combined with adsorbed heavy metals caused adverse effects on daphnia swimming and molting behavior, which is supposed to lead to chronic toxicity.

Loose nanofiltration membrane for dye/salt separation through interfacial polymerization with in-situ generated TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Qi; Fan, Lin; Yang, Zhen; Zhang, Runnan; Liu, Ya-nan; He, Mingrui; Su, Yanlei; Jiang, Zhongyi

2017-07-01

In this study, a high flux nanofiltration (NF) membrane with hybrid polymer-nanoparticle active layer was fabricated by chemical crosslinking of piperazine (PIP) and 1, 3, 5-benzene tricarbonyl trichloride (TMC). An in-situ generated method was applied to deposit titanium dioxide (TiO2) nanoparticles uniformly on the membrane surface, leading to the enhancement of the surface hydrophilicity, roughness and relative surface area of the polyamide (PA) layer. The morphology of the modified membrane was investigated by scanning electron microscopy (SEM) and Atomic force microscopy (AFM), also energy dispersive X-ray microanalysis (EDX) was used to analyze the distribution of Ti element. Chemical structure was observed by Fourier transmission infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Remarkably, the optimal water flux of the loose NF membrane was 65.0 Lm-2 h-1 bar-1 nearly 5 times as much as the pure PA membrane flux. The rejections of the loose NF membranes for dyes were almost all greater than 95.0%, while the rejection for sodium sulfate (Na2SO4) was only about 17.0%, which indicated that the modified membrane had an impressive potential application for dye desalination and purification.

Tribological Properties of TiO2/SiO2 Double Layer Coatings Deposited on CP-Ti

NASA Astrophysics Data System (ADS)

Çomakli, O.; Yazici, M.; Yetim, T.; Yetim, A. F.; Çelik, A.

In the present paper, the influences of different double layer on wear and scratch performances of commercially pure Titanium (CP-Ti) were investigated. TiO2/SiO2 and SiO2/TiO2 double layer coatings were deposited on CP-Ti by sol-gel dip coating process and calcined at 750∘C. The phase structure, cross-sectional morphology, composition, wear track morphologies, adhesion properties, hardness and roughness of uncoated and coated samples were characterized with X-ray diffraction, scanning electron microscopy (SEM), nano-indentation technique, scratch tester and 3D profilometer. Also, the tribological performances of all samples were investigated by a pin-on-disc tribo-tester against Al2O3 ball. Results showed that hardness, elastic modulus and adhesion resistance of double layer coated samples were higher than untreated CP-Ti. It was found that these properties of TiO2/SiO2 double layer coatings have higher than SiO2/TiO2 double layer coating. Additionally, the lowest friction coefficient and wear rates were obtained from TiO2/SiO2 double layer coatings. Therefore, it was seen that phase structure, hardness and film adhesion are important factors on the tribological properties of double layer coatings.

He+ ion irradiation response of Fe–TiO2 multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderoglu, O.; Zhou, M. J.; Zhang, J.

2013-04-01

The accumulation of radiation-induced defect clusters and He bubble formation in He+ ion irradiated nanocrystalline TiO2 and Fe–TiO2 multilayer thin films were investigated using transmission electron microscopy (TEM). Prior to ion irradiation it was found that the crystallinity of TiO2 layers depends on the individual layer thickness: While all TiO2 layers are amorphous at 5 nm individual layer thickness, at 100 nm they are crystalline with a rutile polymorph. After He+ irradiation up to ~6 dpa at room temperature, amorphization of TiO2 layers was not observed in both nanocrystalline TiO2 single layers and Fe–TiO2 multilayers. The suppression of radiation-induced amorphizationmore » in TiO2 is interpreted in terms of a high density of defect sinks in these nano-composites in the form of Fe–TiO2 interphase boundaries and columnar grains within each layer with nano-scale intercolumnar porosity. In addition, a high concentration of He is believed to be trapped at these interfaces in the form of sub-nanometer-scale clusters retarding the formation of relatively larger He bubbles that can be resolved in TEM.« less

Influence of septic system wastewater treatment on titanium dioxide nanoparticle subsurface transport mechanisms.

PubMed

Waller, Travis; Marcus, Ian M; Walker, Sharon L

2018-06-04

Engineered nanomaterials (ENMs) are commonly incorporated into food and consumer applications to enhance a specific product aspect (i.e., optical properties). Life cycle analyses revealed ENMs can be released from products during usage and reach wastewater treatment plants (WWTPs), with titanium dioxide (TiO 2 ) accounting for a large fraction. As such, food grade (FG) TiO 2 , a more common form of TiO 2 in wastewater, was used in this study. Nanomaterials in WWTPs have been well characterized, although the problematic septic system has been neglected. Elution and bioaccumulation of TiO 2 ENMs from WTTPs in downriver sediments and microorganisms has been observed; however, little is known about mechanisms governing the elution of FG TiO 2 from the septic drainage system. This study characterized the transport behavior and mechanisms of FG TiO 2 particles in porous media conditions after septic waste treatment. FG and industrial grade (IG) TiO 2 (more commonly studied) were introduced to septic tank effluent and low-ionic strength electrolyte solutions prior to column transport experiments. Results indicate that FG TiO 2 aggregate size (200-400 nm) remained consistent across solutions. Additionally, elution of FG and IG TiO 2 was greatest in septic effluent at the higher nanoparticle concentration (100 ppm). FG TiO 2 was well retained at the low (2 ppm) concentration in septic effluent, suggesting that particles that escape the septic system may still be retained in drainage field before reaching the groundwater system, although eluted particles are highly stabilized. Findings provide valuable insight into the significance of the solution environment at mediating differences observed between uniquely engineered nanomaterials. Graphical abstract.

Effects of titanium dioxide (TiO2) nanoparticles on the photodissolution of particulate organic matter: Insights from fluorescence spectroscopy and environmental implications.

PubMed

Hu, Bin; Wang, Peifang; Hou, Jun; Wang, Chao; Qian, Jin; Zhang, Nannan; Yuan, Qiusheng

2017-10-01

Widely used titanium dioxide (TiO 2 ) nanoparticles are likely to accumulate ultimately in sediments and potentially pose a risk to water ecosystems. This study evaluated the effect of TiO 2 nanoparticles on the photodissolution of particulate organic matter (POM) through fluorescence spectroscopy. Excitation-emission matrices and parallel factor analyses revealed that the fluorescent characteristics of produced dissolved organic matter (DOM) during photodissolution of suspended sediment and synthetic particulate organic matter (SPOM) were primarily humic-like. SPOM particles appeared to simulate well the photodissolution of suspended sediment. Quasi-complete increases in fluorescence intensity and chromophoric DOM (CDOM) abundance were reached after 90, 60, and 50 min irradiation for TiO 2 concentrations of 0, 2, and 5 mg L -1 , respectively. The faster increment of fluorescence intensity and CDOM abundance indicated the photocatalytic dissolution of SPOM, as opposite charges between TiO 2 and SPOM at pH = 4 favored the adsorption of TiO 2 onto SPOM. For sediments, the CDOM abundance and fluorescence intensity decreased with increasing TiO 2 concentration, resulting from the photocatalytic degradation of photoproduced DOM from sediments. These results demonstrated that pH plays an important role in the photocatalytic dissolution of POM by TiO 2 . Therefore, appropriate pH controls should be implemented when TiO 2 are used to treat sediments contaminated with organic pollutants. Finally, with increasing use of TiO 2 , its accumulation in sediments may affect the fate of carbon, nutrients, and heavy metals in shallow-water ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interface architecture between TiO2/perovskite, perovskite/hole transport layer, and perovskite grain boundary(Conference Presentation)

NASA Astrophysics Data System (ADS)

Hayase, Shuzi; Hirotani, Daisuke; Moriya, Masahiro; Ogomi, Yuhei; Shen, Qing; Yoshino, Kenji; Toyoda, Taro

2016-09-01

In order to examine the interface structure of TiO2/perovskite layer, quartz crystal microbalance sensor (QCM) was used. On the QCM sensor, TiO2 layer was fabricated and the PbI2 solution in Dimethylformamide (DMF) was passed on the QCM sensor to estimate the adsorption density of the PbI2 on the titania2. The amount of PbI2 adsorption on TiO2 surface increased as the adsorption time and leveled off at a certain time. PbI2 still remained even after the solvent only (DMF) was passed on the TiO2 layer on QCM (namely rinsing with DMF), suggesting that the PbI2 was tightly bonded on the TiO2 surface. The bonding structure was found to be Ti-O-Pb linkage by XPS analysis. We concluded that the Ti-OH on the surface of TiO2 reacts with I-Pb-I to form Ti-O-Pb-I and HI (Fig.1 B). The surface trap density was measured by thermally stimulated current (TSC) method. Before the PbI2 passivation, the trap density of TiO2 was 1019 cm3. The trap density decreased to 1016/cm3 after the PbI2 passivation, suggesting that the TiO2 surface trap was passivated with I-Pb-I. The passivation density was tuned by the concentration of PbI2 in DMF, by which TiO2 layer was passivated. Perovskite solar cells were fabricated on the passivated TiO2 layer with various PbI2 passivation densities by one step process (mixture of PbI2 + MAI in DMF). It was found that Jsc increased with an increase in the Ti-O-Pb density. We concluded that the interface between TiO2 and perovskite layer has passivation structure consisting of Ti-O-Pb-I which decreases the trap density of the interfaces and supresses charge recombination. The effect of Cl anion on high efficiency is still controversial when perovskite layer is prepared by one step method from the mixture of MAI and PbCl2. It was found that adsorption density of PbCl2 on TiO2 surface was much higher than that of PbI2 from the experiment using QCM sensor. After the surface was washed with DMF, Cl and Pb were detected. These results suggest that the TiO2 surface was much more passivated by PbCl2 than by PbI2. This may explain partially the high efficiency when the perovskite layer was fabricated by one step process consisting of MAI and PbCl2 solution. We also observed that the crystal size increased with an increase in the amount of Cl anion which of course one of the explanation of the high efficiency. The interface of hole transport layer/perovskite layer, and between perovskite layer /perovskite layer (grain boundary) was passivated with organic amines. The passivation was also effective for increasing Voc and Jsc. This was explained by the results of transient absorption spectroscopy that the charge recombination time between hole transport payer/perovskite layer increased from 0.3 μsec to 60 μsec.

Retention of titanium dioxide nanoparticles in biological activated carbon filters for drinking water and the impact on ammonia reduction.

PubMed

Liu, Zhiyuan; Yu, Shuili; Park, Heedeung; Liu, Guicai; Yuan, Qingbin

2016-06-01

Given the increasing discoveries related to the eco-toxicity of titanium dioxide (TiO2) nanoparticles (NPs) in different ecosystems and with respect to public health, it is important to understand their potential effects in drinking water treatment (DWT). The effects of TiO2 NPs on ammonia reduction, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in biological activated carbon (BAC) filters for drinking water were investigated in static and dynamic states. In the static state, both the nitrification potential and AOB were significantly inhibited by 100 μg L(-1) TiO2 NPs after 12 h (p < 0.05), and the threshold decreased to 10 μg L(-1) with prolonged exposure (36 h, p < 0.05). However, AOA were not considerably affected in any of the tested conditions (p > 0.05). In the dynamic state, different amounts of TiO2 NP pulses were injected into three pilot-scale BAC filters. The decay of TiO2 NPs in the BAC filters was very slow. Both titanium quantification and scanning electron microscope analysis confirmed the retention of TiO2 NPs in the BAC filters after 134 days of operation. Furthermore, the TiO2 NP pulses considerably reduced the performance of ammonia reduction. This study identified the retention of TiO2 NPs in BAC filters and the negative effect on the ammonia reduction, suggesting a potential threat to DWT by TiO2 NPs.

Well-crystallized mesoporous TiO2 shells for enhanced photocatalytic activity: prepared by carbon coating and silica-protected calcination.

PubMed

Zhang, Zewu; Zhou, Yuming; Zhang, Yiwei; Zhou, Shijian; Shi, Junjun; Kong, Jie; Zhang, Sicheng

2013-04-14

Mesoporous anatase-phase TiO2 hollow shells were successfully fabricated by the solvothermal and calcination process. This method involves preparation of SiO2@TiO2 core-shell colloidal templates, sequential deposition of carbon and then silica layers through solvothermal and sol-gel processes, crystallization of TiO2 by calcination and finally removal of the inner and outer silica to produce hollow anatase TiO2 shells. The prepared samples were characterized by transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption isotherms and UV-vis absorption spectroscopy. The results show that a uniform carbon layer is coated on the core-shell particles through the solvothermal process. The combustion of carbon offers the space for the TiO2 to further grow into large crystal grains, and the outer silica layer serves as a barrier against the excessive growth of anatase TiO2 nanocrystals. Furthermore, the initial crystallization of TiO2 generated in the carbon coating step and the heat generated by the combustion of the carbon layer allow the crystallization of TiO2 at a relatively low temperature without changing the uniform structure. When used as photocatalysts for the oxidation decomposition of Rhodamine B in aqueous solution under UV irradiation, the hollow TiO2 shells showed enhanced catalytic activity. Moreover, the TiO2 hollow shells prepared with optimal crystallinity by this method showed a higher performance than commercial P25 TiO2.

Sol-gel preparation of self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective coating for solar glass

NASA Astrophysics Data System (ADS)

Lin, Wensheng; Zheng, Jiaxian; Yan, Lianghong; Zhang, Xinxiang

2018-03-01

Self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective (AR) coating is prepared by sol-gel process. SiO2 sol is prepared by using tetraethyl orthosilicate (TEOS) as precursor and ammonia as catalyst, while TiO2 sol was prepared by using tetrabutyl orthotitanate (TBOT) as precursor and hydrochloric acid as catalyst. The effect of TiO2 content on refractive index, abrasion-resistance and photo-catalytic activity of SiO2-TiO2 hybrid thin films or powders is systematically investigated. It is found that the refractive index of SiO2-TiO2 hybrid thin films increases gradually from 1.18 to 1.53 as the weight ratio of TiO2 to SiO2 increased from 0 to 1.0. The SiO2-TiO2 hybrid thin film and powder possesses good abrasion-resistance and photo-catalytic activity, respectively, as the weight ratio of TiO2 to SiO2 is 0.4. The degradation degree of Rhodamine B by SiO2-TiO2 hybrid powder is 88.3%. Finally, SiO2-TiO2/SiO2-TiO2 double-layer AR coating with high transmittance, abrasion-resistance and self-cleaning property is realized.

Analysis of Ti and TiO2 nanolayers by total reflection X-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Kubala-Kukuś, A.; Banaś, D.; Stabrawa, I.; Szary, K.; Sobota, D.; Majewska, U.; Wudarczyk-Moćko, J.; Braziewicz, J.; Pajek, M.

2018-07-01

Total reflection X-ray photoelectron spectroscopy (TRXPS) is applied in the analysis of Ti and TiO2 nanolayers deposited on silicon and silicon dioxide substrates. The idea of application of total-reflection phenomenon for exciting X-ray used in the XPS technique is briefly discussed. The experimental setup and measurement conditions for the studied Ti and TiO2 layers are presented. The XPS spectra were registered both for the non-total and total reflection regimes. The survey spectra and C1s, N1s, Ti2p and O1s photoelectron peaks are shown. For energy calibration, the position of C1s photoelectron peak was applied (C-C component, binding energy 284.8 eV). The peak to background ratios are discussed as regards the dependence of the excitation angle. An increase of this ratio for the glancing angle 1°, being below critical angle of the X-ray beam and sample material, results in an improvement of XPS detection limit by factor up to 2. In the case of the Ti nanolayer, additionally, the thickness of the overlayer TiO2 is determined. As an example of applying the TRXPS technique, the analysis of Ti nanolayers implanted by highly charged Xe35+ ions of 280 keV energy is discussed. The Xe3d and O1s photoelectron peaks are presented and discussed.

Titanium dioxide nanoparticles exacerbate DSS-induced colitis: role of the NLRP3 inflammasome

PubMed Central

Ruiz, Pedro A; Morón, Belen; Becker, Helen M; Lang, Silvia; Atrott, Kirstin; Spalinger, Marianne R; Scharl, Michael; Wojtal, Kacper A; Fischbeck-Terhalle, Anne; Frey-Wagner, Isabelle; Hausmann, Martin; Kraemer, Thomas; Rogler, Gerhard

2017-01-01

Objective Western lifestyle and diet are major environmental factors playing a role in the development of IBD. Titanium dioxide (TiO2) nanoparticles are widely used as food additives or in pharmaceutical formulations and are consumed by millions of people on a daily basis. We investigated the effects of TiO2 in the development of colitis and the role of the nucleotide-binding oligomerisation domain receptor, pyrin domain containing (NLRP)3 inflammasome. Design Wild-type and NLRP3-deficient mice with dextran sodium sulfate-induced colitis were orally administered with TiO2 nanoparticles. The proinflammatory effects of TiO2 particles in cultured human intestinal epithelial cells (IECs) and macrophages were also studied, as well as the ability of TiO2 crystals to traverse IEC monolayers and accumulate in the blood of patients with IBD using inductively coupled plasma mass spectrometry. Results Oral administration of TiO2 nanoparticles worsened acute colitis through a mechanism involving the NLRP3 inflammasome. Importantly, crystals were found to accumulate in spleen of TiO2-administered mice. In vitro, TiO2 particles were taken up by IECs and macrophages and triggered NLRP3-ASC-caspase-1 assembly, caspase-1 cleavage and the release of NLRP3-associated interleukin (IL)-1β and IL-18. TiO2 also induced reactive oxygen species generation and increased epithelial permeability in IEC monolayers. Increased levels of titanium were found in blood of patients with UC having active disease. Conclusion These findings indicate that individuals with a defective intestinal barrier function and pre-existing inflammatory condition, such as IBD, might be negatively impacted by the use of TiO2 nanoparticles. PMID:26848183

Titanium dioxide in our everyday life; is it safe?

PubMed Central

Skocaj, Matej; Filipic, Metka; Petkovic, Jana; Novak, Sasa

2011-01-01

Background Titanium dioxide (TiO2) is considered as an inert and safe material and has been used in many applications for decades. However, with the development of nanotechnologies TiO2 nanoparticles, with numerous novel and useful properties, are increasingly manufactured and used. Therefore increased human and environmental exposure can be expected, which has put TiO2 nanoparticles under toxicological scrutiny. Mechanistic toxicological studies show that TiO2 nanoparticles predominantly cause adverse effects via induction of oxidative stress resulting in cell damage, genotoxicity, inflammation, immune response etc. The extent and type of damage strongly depends on physical and chemical characteristics of TiO2 nanoparticles, which govern their bioavailability and reactivity. Based on the experimental evidence from animal inhalation studies TiO2 nanoparticles are classified as “possible carcinogenic to humans” by the International Agency for Research on Cancer and as occupational carcinogen by the National Institute for Occupational Safety and Health. The studies on dermal exposure to TiO2 nanoparticles, which is in humans substantial through the use of sunscreens, generally indicate negligible transdermal penetration; however data are needed on long-term exposure and potential adverse effects of photo-oxidation products. Although TiO2 is permitted as an additive (E171) in food and pharmaceutical products we do not have reliable data on its absorption, distribution, excretion and toxicity on oral exposure. TiO2 may also enter environment, and while it exerts low acute toxicity to aquatic organisms, upon long-term exposure it induces a range of sub-lethal effects. Conclusions Until relevant toxicological and human exposure data that would enable reliable risk assessment are obtained, TiO2 nanoparticles should be used with great care. PMID:22933961

Derivation of the stress-strain behavior of the constituents of bio-inspired layered TiO2/PE-nanocomposites by inverse modeling based on FE-simulations of nanoindentation test.

PubMed

Lasko, G; Schäfer, I; Burghard, Z; Bill, J; Schmauder, S; Weber, U; Galler, D

2013-03-01

Owing to the apparent simple morphology and peculiar properties, nacre, an iridescent layer, coating of the inner part of mollusk shells, has attracted considerable attention of biologists, material scientists and engineers. The basic structural motif in nacre is the assembly of oriented plate-like aragonite crystals with a 'brick' (CaCO3 crystals) and 'mortar' (macromolecular components like proteins) organization. Many scientific researchers recognize that such structures are associated with the excellent mechanical properties of nacre and biomimetic strategies have been proposed to produce new layered nanocomposites. During the past years, increasing efforts have been devoted towards exploiting nacre's structural design principle in the synthesis of novel nanocomposites. However, the direct transfer of nacre's architecture to an artificial inorganic material has not been achieved yet. In the present contribution we report on laminated architecture, composed of the inorganic oxide (TiO2) and organic polyelectrolyte (PE) layers which fulfill this task. To get a better insight and understanding concerning the mechanical behaviour of bio-inspired layered materials consisting of oxide ceramics and organic layers, the elastic-plastic properties of titanium dioxide and organic polyelectrolyte phase are determined via FE-modelling of the nanoindentation process. With the use of inverse modeling and based on numerical models which are applied on the microscopic scale, the material properties of the constituents are derived.

Biotemplated Synthesis of Anatase Titanium Dioxide Nanoparticles via Lignocellulosic Waste Material

PubMed Central

Bagheri, Samira; Abd Hamid, Sharifah Bee

2014-01-01

Anatase titanium dioxide nanoparticles (TiO2-NPs) were synthesized by sol-gel method using rice straw as a soft biotemplate. Rice straw, as a lignocellulosic waste material, is a biomass feedstock which is globally produced in high rate and could be utilized in an innovative approach to manufacture a value-added product. Rice straw as a reliable biotemplate has been used in the sol-gel method to synthesize ultrasmall sizes of TiO2-NPs with high potential application in photocatalysis. The physicochemical properties of titanium dioxide nanoparticles were investigated by a number of techniques such as X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), ultraviolet visible spectra (UV-Vis), and surface area and pore size analysis. All results consensually confirmed that particle sizes of synthesized titanium dioxide were template-dependent, representing decrease in the nanoparticles sizes with increase of biotemplate concentration. Titanium dioxide nanoparticles as small as 13.0 ± 3.3 nm were obtained under our experimental conditions. Additionally, surface area and porosity of synthesized TiO2-NPs have been enhanced by increasing rice straw amount which results in surface modification of nanoparticles and potential application in photocatalysis. PMID:25126547

A study of the uptake and biodistribution of nano-titanium dioxide using in vitro and in vivo models of oral intake

NASA Astrophysics Data System (ADS)

MacNicoll, Alan; Kelly, Mick; Aksoy, Hatice; Kramer, Evelien; Bouwmeester, Hans; Chaudhry, Qasim

2015-02-01

Certain food additives may contain a sizeable fraction of particles in the nanoscale. However, little is known about the fate, behaviour and toxicological effects of orally-ingested nanoparticles. This study investigated the uptake and biodistribution of nano- and larger-sized titanium dioxide (TiO2) using an in vitro model of gut epithelium and in vivo in rat. The results of the in vivo study showed that oral administration of 5 mg/kg body weight of TiO2 nano- or larger particles did not lead to any significant translocation of TiO2 (measured as titanium) either to blood, urine or to various organs in rat at any of the time intervals studied over a 96 h post-administration period. Different methods used for dispersing particles did not affect the uptake, and orally administered TiO2 was found excreted in the faeces over a period of time. The in vitro study provided further evidence for the lack of translocation of TiO2 across the gut epithelium model. The overall evidence from both in vivo and in vitro studies did not support that oral ingestion of nano- or larger particles of TiO2 via food would result in any significant internal exposure of the consumer to the nanoparticles. The dietary TiO2 nanoparticles are likely to be excreted in the faeces.

Band Alignment-Driven Oxidative Injury to the Skin by Anatase/Rutile Mixed-Phase Titanium Dioxide Nanoparticles under Sunlight Exposure.

PubMed

Sun, Xiujuan; Chang, Yun; Cheng, Yan; Feng, Yanlin; Zhang, Haiyuan

2018-04-12

Anatase/rutile mixed-phase titanium dioxide (TiO2) nanoparticles (NPs) have been found in cosmetics and cotton textiles. Once exposed to sunlight, mixed-phase TiO2 NPs are even more toxic to cells than pure phase NPs, however, the underlying mechanism remains unclear. Considering the unique anatase/rutile heterojunction structure existing in mixed-phase NPs, the potent toxicity of mixed-phase TiO2 NPs probably originates from the high reactive oxygen species (ROS) production because the anatase/rutile heterojunction is constituted by the staggered energy bands that facilitate the electron-hole separation at the interface due to the band alignment. In the present study, a library of mixed-phase TiO2 NPs with different anatase/rutile ratios was established to investigate the potential property-activity relationship and further clarify the underlying molecular mechanism. Under sunlight exposure, these mixed-phase TiO2 NPs could produce significant abiotic ROS and induce hierarchical oxidative stress to HaCaT skin cells and mice skin. The ROS magnitude and toxicity potential of these NPs were found to be proportional to their energy band bending (BB) levels. This means that the toxicity of mixed-phase TiO2 NPs can be correlated to their heterojunction density, and the toxicity potential of mixed-phase TiO2 NPs can be weighed by their BB levels.

Formation and accumulation of radiation-induced defects and radiolysis products in modified lithium orthosilicate pebbles with additions of titanium dioxide

NASA Astrophysics Data System (ADS)

Zarins, Arturs; Valtenbergs, Oskars; Kizane, Gunta; Supe, Arnis; Knitter, Regina; Kolb, Matthias H. H.; Leys, Oliver; Baumane, Larisa; Conka, Davis

2016-03-01

Lithium orthosilicate (Li4SiO4) pebbles with 2.5 wt.% excess of silicon dioxide (SiO2) are the European Union's designated reference tritium breeding ceramics for the Helium Cooled Pebble Bed (HCPB) Test Blanket Module (TBM). However, the latest irradiation experiments showed that the reference Li4SiO4 pebbles may crack and form fragments under operation conditions as expected in the HCPB TBM. Therefore, it has been suggested to change the chemical composition of the reference Li4SiO4 pebbles and to add titanium dioxide (TiO2), to obtain lithium metatitanate (Li2TiO3) as a second phase. The aim of this research was to investigate the formation and accumulation of radiation-induced defects (RD) and radiolysis products (RP) in the modified Li4SiO4 pebbles with different contents of TiO2 for the first time, in order to estimate and compare radiation stability. The reference and the modified Li4SiO4 pebbles were irradiated with accelerated electrons (E = 5 MeV) up to 5000 MGy absorbed dose at 300-990 K in a dry argon atmosphere. By using electron spin resonance (ESR) spectroscopy it was determined that in the modified Li4SiO4 pebbles, several paramagnetic RD and RP are formed and accumulated, like, E' centres (SiO33-/TiO33-), HC2 centres (SiO43-/TiO3-) etc. On the basis of the obtained results, it is concluded that the modified Li4SiO4 pebbles with TiO2 additions have comparable radiation stability with the reference pebbles.

An innovative approach to synthesize highly-ordered TiO2 nanotubes.

PubMed

Isimjan, Tayirjan T; Yang, D Q; Rohani, Sohrab; Ray, Ajay K

2011-02-01

An innovative route to prepare highly-ordered and dimensionally controlled TiO2 nanotubes has been proposed using a mild sonication method. The nanotube arrays were prepared by the anodization of titanium in an electrolyte containing 3% NH4F and 5% H2O in glycerol. It is demonstrated that the TiO2 nanostructures has two layers: the top layer is TiO2 nanowire and underneath is well-ordered TiO2 nanotubes. The top layer can easily fall off and form nanowires bundles by implementing a mild sonication after a short annealing time. We found that the dimensions of the TiO2 nanotubes were only dependent on the anodizing condition. The proposed technique may be extended to fabricate reproducible well-ordered TiO2 nanotubes with large area on other metals.

Interactions of ciprofloxacin (CIP), titanium dioxide (TiO2) nanoparticles and natural organic matter (NOM) in aqueous suspensions.

PubMed

Fries, Elke; Crouzet, Catherine; Michel, Caroline; Togola, Anne

2016-09-01

The aim of the present study was to investigate interactions of the antibiotic ciprofloxacin (CIP), titanium dioxide nanoparticles (TiO2 NP) and natural organic matter (NOM) in aqueous suspensions. The mean hydrodynamic diameter of particles of TiO2 NP and NOM in the suspensions ranged from 113 to 255nm. During batch experiments the radioactivity resulting from (14)CIP was determined in the filtrate (filter pore size 100nm) by scintillation measurements. Up to 72h, no significant sorption of NOM to TiO2 NP was observed at a TiO2 NP concentration of 5mg/L. When the concentration of TiO2 NP was increased to 500mg/L, a small amount of NOM of 9.5%±0.6% was sorbed at 72h. The low sorption affinity of NOM on TiO2 NP surfaces could be explained by the negative charge of both components in alkaline media or by the low hydrophobicity of the NOM contents. At a TiO2 NP concentration of 5mgL(-1), the sorption of CIP on TiO2 NP was insignificant (TiO2 NP/CIP ratio: 10). When the TiO2 NP/CIP ratio was increased to 1000, a significant amount of 53.6%±7.2% of CIP was sorbed on TiO2 NP under equilibrium conditions at 64h. In alkaline media, CIP is present mainly as zwitterions which have an affinity to sorb on negatively charged TiO2 NP surfaces. The sorption of CIP on TiO2 NP in the range of TiO2 NP concentrations currently estimated for municipal wastewater treatment plants is estimated to be rather low. The Freundlich sorption coefficients (KF) in the presence of NOM of 2167L(n)mgmg(-n)kg(-1) was about 10 times lower than in the absence of NOM. This is an indication that the particle fraction of NOM<100nm could play a role as a carrier for ionic organic micro-pollutants as CIP. Copyright © 2015 Elsevier B.V. All rights reserved.

Structure and Properties of VO2 and Titanium Dioxide Based Epitaxial Heterostructures Integrated with Silicon and Sapphire Substrates

NASA Astrophysics Data System (ADS)

Bayati, Mohammad Reza

The main focus of this study was placed on structure-property correlation in TiO2 and VO2 based epitaxial heterostructures where the photochemical and electrical properties were tuned through microstructural engineering. In the framework of domain matching epitaxy, epitaxial growth of TiO2 and VO2 heterostructures on different substrates were explained. The theta-2theta and ϕ scan X-ray diffraction measurements and detailed high resolution electron microscopy studies corroborated our understanding of the epitaxial growth and the crystallographic arrangement across the interfaces. The influence of the laser and substrate variables on structural characteristics of the films was investigated using X-ray photoelectron spectroscopy, room temperature photoluminescence spectroscopy, and UV-Vis spectrophotometry. In addition, morphological studies were performed by atomic force microscopy. Photochemical properties of the heterostructures were assessed through measuring surface wettability characteristics and photocatalytic reaction rate constant of degradation of 4-chlorophenol under ultraviolet and visible irradiations. We also studied electrical properties employing 4-probe measurement technique. The effect of post treatment processes, such as vacuum annealing and laser treatment, on structure and properties was investigated as well. The role of point defects and deviation from the stoichiometry on photochemical and electrical properties was addressed. In this research, TiO2 epilayers with controlled phase structure, defect content, and crystallographic alignments were grown on sapphire and silicon substrates. Integration with silicon was achieved using cubic and tetragonal yttria-stabilized zirconia buffer layers. I was able to tune the phase structure of the TiO2 based heterostructures from pure rutile to pure anatase and establish an epitaxial relationship across the interfaces in each case. These heterostructures were used for two different purposes. First, their application in environmental remediation was taken into account. The photochemical efficiency of the samples was evaluated under ultraviolet and visible illuminations. I was able to establish a correlation between the growth conditions and the photocatalytic activity of single crystalline TiO 2 thin films. Visible-light-responsive TiO2 films were fabricated via vacuum annealing of the samples where point defects, namely oxygen vacancies and titanium interstitial, are surmised to play a critical role. An ultrafast switching was observed in wetting characteristics of the single crystalline rutile TiO2 films from a hydrophobic state to a superhydrophilic state by single pulsed excimer laser annealing. It was observed that the laser annealing almost doubles the photocatalytic efficiency of the anatase epitaxial thin films. I was able to measure the photochemical properties of the rutile and the anatase TiO2 heterostructures in a controlled way due to the single crystalline nature of the films. Second, the rutile TiO2 epilayers with different out-of-plane orientations were deposited and used as a platform for VO2 based epitaxial heterostructures with the aim of manipulating of microstructure and electrical properties of the VO 2 films. Vanadium dioxide (VO2) is an interesting material due to the abrupt change in electrical resistivity and infrared transmittance at about 68 °C. The transition temperature can be tuned through microstructural engineering. It was the idea behind using rutile TiO2 with different crystallographic orientations as a template to tune the semiconductor to metal transition characteristics of the VO2 top layer. I successfully grew VO2(001), VO2(100), and VO2(2¯01) epitaxial thin films on TiO2(100)/c-sapphire, TiO2(101)/r-sapphire, and TiO2(001)/ m-sapphire platforms, respectively. It was observed that tetragonal phase of VO2 was stabilized at lower temperatures leading to a significant decrease in the semiconductor to metal transition temperature. In other words, we were able to tune the transition temperature of the VO 2 epitaxial heterostructures. This achievement introduces the VO 2 based single crystalline heterostructures as a promising candidate for a wide range of applications where different transition temperatures are required. The epitaxial relationships were established and atomic arrangement across the interfaces was studied in detail.

Effect of screen printing type on transparent TiO2 layer as the working electrode of dye sensitized solar cell (DSSC) for solar windows applications

NASA Astrophysics Data System (ADS)

Nurosyid, F.; Furqoni, L.; Supriyanto, A.; Suryana, R.

2016-11-01

The working electrode based on semiconductor TiO2 DSSC has been fabricated by screen printing method. This study aim is to determine the effect of the screen type on TiO2 layer as the working electrode of DSSC. Screen used for deposition of TiO2 has the types of; T- 49, T-55 and T-61. TiO2 layer was sintered at temperature of 500°C. DSSC structure was composed of semiconductor TiO2 adsorbed dye, an electrolyte solution and a platinum counter electrode. TiO2 layer thickness was characterized by Scanning Electron Microscopy (SEM), while the absorbance was characterized using UV-Vis spectrophotometer and the electrical properties of DSSC were characterized by Keithley I-V measurement. TiO2 layer fabricated by screen T-49 had the biggest thickness that was 3.2 ± 0.3 μm and the highest UV-Vis absorbance wave at the peak wavelength of 315 nm with the absorbance value was 1.7. The I-V characterization showed that the sample fabricated by screen T-49 obtained the greatest efficiency that was 1.0 × 10-1%

Apatite-forming PEEK with TiO2 surface layer coating.

PubMed

Kizuki, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi

2015-01-01

Polyetheretherketone (PEEK) is widely used in orthopedic implants, such as spinal fusion devices, because of its moderate elastic modulus, as well as relatively high mechanical strength. However, it does not bond to living bone, and hence it needs autograft to be fixed to the bone. In this study, we attempted to add bone-bonding properties to PEEK by coating with TiO2 synthesized by the sol-gel process. When a TiO2 sol solution consisting of titanium isopropoxide, water, ethanol, and nitric acid was deposited on a PEEK substrate without any pretreatment, the formed TiO2 gel layer was easily peeled off after subsequent treatments. However, when the same solution was deposited on PEEK that was preliminarily subjected to UV or O2 plasma treatment, the deposited TiO2 gel layer strongly adhered to the substrate even after subsequent treatments. The strong adhesion was attributed to the interaction among the C-O, C=O, and O-C=O groups on the PEEK owing to the UV or O2 plasma treatment and the Ti-O bond of the TiO2 gel. Apatite did not form on the as-formed TiO2 gel layer in a simulated body fluid (SBF) even within 3 days; however, apatite formed after soaking in 0.1 M HCl solution at 80 °C for 24 h. This apatite formation was attributed to positive surface charge of the TiO2 gel layer induced by the acid treatment. The PEEK with the TiO2 gel layer coating formed by the proposed process is expected to bond to living bone, because a positively charged titanium oxide which facilitates the formation of apatite in SBF within a short period is known to bond to living bone.

Tuning band alignment by CdS layers using a SILAR method to enhance TiO2/CdS/CdSe quantum-dot solar-cell performance.

PubMed

Zhang, Bingkai; Zheng, Jiaxin; Li, Xiaoning; Fang, Yanyan; Wang, Lin-Wang; Lin, Yuan; Pan, Feng

2016-04-28

We report tuning band alignment by optimized CdS layers using a SILAR method to achieve the recorded best performance with about 6% PCE in TiO2/CdS/CdSe QDSSCs. Combining experimental and theoretical studies, we find that a better lattices match between CdS and TiO2 assists the growth of CdSe, and the combined effect of charge transfer and surface dipole moment at the TiO2/CdS/CdSe interface shifts the energy levels of TiO2 upward and increases Voc of the solar cells. More importantly, the band gap of CdS buffer layers is sensitive to the distortion induced by lattice mismatch and numbers of CdS layers. For example, the barrier for charge transfer disappears when there are more than 4 layers of CdS, facilitating the charge injection from CdSe to TiO2.

Defective TiO 2 with high photoconductive gain for efficient and stable planar heterojunction perovskite solar cells

DOE PAGES

Li, Yanbo; Cooper, Jason K.; Liu, Wenjun; ...

2016-08-18

Formation of planar heterojunction perovskite solar cells exhibiting both high efficiency and stability under continuous operation remains a challenge. Here, we show this can be achieved by using a defective TiO 2 thin film as the electron transport layer. TiO 2 layers with native defects are deposited by electron beam evaporation in an oxygen-deficient environment. Deep-level hole traps are introduced in the TiO 2 layers and contribute to a high photoconductive gain and reduced photocatalytic activity. The high photoconductivity of the TiO 2 electron transport layer leads to improved efficiency for the fabricated planar devices. A maximum power conversion efficiencymore » of 19.0% and an average PCE of 17.5% are achieved. In addition, the reduced photocatalytic activity of the TiO 2 layer leads to enhanced long-Term stability for the planar devices. Under continuous operation near the maximum power point, an efficiency of over 15.4% is demonstrated for 100 h.« less

OXYGENATION OF HYDROCARBONS USING NANOSTRUCTURED TIO2 AS A PHOTOCATALYST: A GREEN ALTERNATIVE

EPA Science Inventory

High-value organic compounds have been synthesized successfully from linear and cyclic saturated hydrocarbons by a photocatalytic oxidation process using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxygenated in both aqueous and gaseous...

Engineering of highly ordered TiO2 nanopore arrays by anodization

NASA Astrophysics Data System (ADS)

Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

2016-07-01

Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

Titanium dioxide nanotube membranes for solar energy conversion: effect of deep and shallow dopants.

PubMed

Ding, Yuchen; Nagpal, Prashant

2017-04-12

Nanostructured titanium dioxide (TiO 2 ) has been intensively investigated as a material of choice for solar energy conversion in photocatalytic, photoelectrochemical, photovoltaic, and other photosensitized devices for converting light into chemical feedstocks or electricity. Towards management of light absorption in TiO 2 , while the nanotubular structure improves light absorption and simultaneous charge transfer to mitigate problems due to the indirect bandgap of the semiconductor, typically dopants are used to improve light absorption of incident solar irradiation in the wide bandgap of TiO 2 . While these dopants can be critical to the success of these solar energy conversion devices, their effect on photophysical and photoelectrochemical properties and detailed photokinetics are relatively under-studied. Here, we show the effect of deep and shallow metal dopants on the kinetics of photogenerated charged carriers in TiO 2 and the resulting effect on photocatalytic and photoelectrochemical processes using these nanotube membranes. We performed a detailed optical, electronic, voltammetry and electrochemical impedance study to understand the effect of shallow and deep metal dopants (using undoped and niobium- and copper-doped TiO 2 nanotubes) on light absorption, charge transport and charge transfer processes. Using wireless photocatalytic methylene blue degradation and carbon dioxide reduction, and wired photoelectrochemical device measurements, we elucidate the effect of different dopants on solar-to-fuel conversion efficiency and simultaneously describe the photokinetics using a model, to help design better energy conversion devices.

Biologically Self-Assembled Memristive Circuit Elements

DTIC Science & Technology

2010-01-01

hydrothermal approach, TiO2 nanoparticles were synthesized by slowly stirring a 1:3 volumetric ratio mixture of titanium isopropoxide (TTIP) and isopropyl...Synthesis of TiO2 nanoparticles by hydrolysis and peptization of titanium isopropoxide solution. Journal of Materials Processing Technology 2007, 189...important role interfacing with group IV metal oxides such as hafnium, providing a stable linkage to the surface [3]. Titanium dioxide (TiO2), which is

Listeria monocytogenes Behaviour in Presence of Non-UV-Irradiated Titanium Dioxide Nanoparticles

PubMed Central

Ammendolia, Maria Grazia; Iosi, Francesca; De Berardis, Barbara; Guccione, Giuliana; Superti, Fabiana; Conte, Maria Pia; Longhi, Catia

2014-01-01

Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO2 NPs) are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO2 NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS) with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO2 NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO2 NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO2 NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO2 NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts. PMID:24416327

Listeria monocytogenes behaviour in presence of non-UV-irradiated titanium dioxide nanoparticles.

PubMed

Ammendolia, Maria Grazia; Iosi, Francesca; De Berardis, Barbara; Guccione, Giuliana; Superti, Fabiana; Conte, Maria Pia; Longhi, Catia

2014-01-01

Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO2 NPs) are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO2 NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS) with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO2 NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO2 NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO2 NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO2 NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts.

The involvement of coordinative interactions in the binding of dihydrolipoamide dehydrogenase to titanium dioxide-Localization of a putative binding site.

PubMed

Dayan, Avraham; Babin, Gilad; Ganoth, Assaf; Kayouf, Nivin Samir; Nitoker Eliaz, Neta; Mukkala, Srijana; Tsfadia, Yossi; Fleminger, Gideon

2017-08-01

Titanium (Ti) and its alloys are widely used in orthodontic and orthopedic implants by virtue to their high biocompatibility, mechanical strength, and high resistance to corrosion. Biointegration of the implants with the tissue requires strong interactions, which involve biological molecules, proteins in particular, with metal oxide surfaces. An exocellular high-affinity titanium dioxide (TiO 2 )-binding protein (TiBP), purified from Rhodococcus ruber, has been previously studied in our lab. This protein was shown to be homologous with the orthologous cytoplasmic rhodococcal dihydrolipoamide dehydrogenase (rhDLDH). We have found that rhDLDH and its human homolog (hDLDH) share the TiO 2 -binding capabilities with TiBP. Intrigued by the unique TiO 2 -binding properties of hDLDH, we anticipated that it may serve as a molecular bridge between Ti-based medical structures and human tissues. The objective of the current study was to locate the region and the amino acids of the protein that mediate the protein-TiO 2 surface interaction. We demonstrated the role of acidic amino acids in the nonelectrostatic enzyme/dioxide interactions at neutral pH. The observation that the interaction of DLDH with various metal oxides is independent of their isoelectric values strengthens this notion. DLDH does not lose its enzymatic activity upon binding to TiO 2 , indicating that neither the enzyme undergoes major conformational changes nor the TiO 2 binding site is blocked. Docking predictions suggest that both rhDLDH and hDLDH bind TiO 2 through similar regions located far from the active site and the dimerization sites. The putative TiO 2 -binding regions of both the bacterial and human enzymes were found to contain a CHED (Cys, His, Glu, Asp) motif, which has been shown to participate in metal-binding sites in proteins. Copyright © 2017 John Wiley & Sons, Ltd.

Enhanced larvicidal, antibacterial, and photocatalytic efficacy of TiO2 nanohybrids green synthesized using the aqueous leaf extract of Parthenium hysterophorus.

PubMed

Thandapani, Keerthika; Kathiravan, Manikandan; Namasivayam, Elangovan; Padiksan, Indira Arulselvi; Natesan, Geetha; Tiwari, Manish; Giovanni, Benelli; Perumal, Venkatachalam

2018-04-01

Titanium dioxide nanoparticles are emerging as a biocompatible nanomaterial with multipurpose bioactivities. In this study, titanium dioxide (TiO 2 ) nanoparticles were effectively synthesized using the aqueous leaf extracts of Parthenium hysterophorus prepared by microwave irradiation. TiO 2 nanoparticles were fabricated by treating the P. hysterophorus leaf extracts with the TiO 4 solution. Biologically active compounds such as alcohols, phenols, alkanes, and fluoroalkanes were involved in bioreduction of TiO 4 into TiO 2 . The formation of green-engineered TiO 2 nanoparticles was confirmed by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy and further characterized by X-ray diffraction (XRD) studies. UV-vis spectroscopy analysis showed maximum absorbance at 420 nm due to surface plasmon resonance of synthesized TiO 2 NPs. FTIR spectrum of the engineered TiO 2 NPs showed the presence of bioactive compounds in the leaf extract, which acted as capping and reducing agents. FESEM exhibited an average size of 20-50 nm and a spherical shape of TiO 2 NPs. EDX analysis indicated the presence of TiO 2 NPs by observing the peaks of titanium ions. XRD results pointed out the crystalline nature of engineered TiO 2 NPs. The larvicidal activity of TiO 2 NPs was studied on fourth instar larvae of dengue, Zika virus, and filariasis mosquito vectors Aedes aegypti and Culex quinquefasciatus. Antimicrobial efficacy of TiO 2 NPs was assessed on clinically isolated pathogens Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, and Staphylococcus epidermidis. Besides, we found that TiO 2 NPs are able to quickly degrade the industrially harmful pigments methylene blue, methyl orange, crystal violet, and alizarin red dyes under sunlight illumination. Overall, this novel, simple, and eco-friendly approach can be of interest for the control of vector-borne diseases, as well as to formulate new bactericidal agents and to efficiently degrade dye solutions in the polluted areas.

Study of the Ag-Doped Effect on the LPD-TiO2 Gas Sensing Properties

NASA Astrophysics Data System (ADS)

Georgieva, V. B.; Stefchev, P. L.; Stefanov, P. K.; Raicheva, Z. G.; Atanassov, M. J.; Lazarov, Y. V.

2010-01-01

In this investigation, the gas-sensing properties of TiO2 thin layers are enhanced by Ag-doping. The TiO2 layers are prepared by the method of Liquid Phase Deposition (LPD) through a reaction between the metal fluorocomplex and boric acid in aqueous solution. The LPD-TiO2 layers are grown on AT-cut quartz resonators with gold electrodes (4 mm diameter). The prepared samples are divided in two (Ag-Doped TiO2 and un-doped TiO2) groups. The Ag-doped TiO2 thin films are created by vertically dipping in AgNO3 diluted water solution and UV irradiation with nine lamps of 6 W power each and light intensity of 0.35 mW/cm2 at room temperature. The sensing properties of two kinds of layers (Ag-doped TiO2 and un-doped TiO2) to NH3 are being studied by the method of Quartz Crystal Microbalance (QCM). The experiments are implemented at different NH3 concentrations—from 10 to 1000 ppm on a special laboratory set-up in dynamic regime. Comparing the results of measured sorbed mass of both kinds of layers show that the sensitivity of TiO2 is significantly affected by Ag presence. The role of Ag is to generate more active surface for TiO2 sorption. The obtained results show that the system QCM—LPD Ag TiO2 can be successfully applied as sensor element for NH3 registration in environment.

Titanium dioxide nanoparticle exposure alters metabolic homeostasis in a cell culture model of the intestinal epithelium and Drosophila melanogaster.

PubMed

Richter, Jonathan W; Shull, Gabriella M; Fountain, John H; Guo, Zhongyuan; Musselman, Laura P; Fiumera, Anthony C; Mahler, Gretchen J

2018-06-01

Nanosized titanium dioxide (TiO 2 ) is a common additive in food and cosmetic products. The goal of this study was to investigate if TiO 2 nanoparticles affect intestinal epithelial tissues, normal intestinal function, or metabolic homeostasis using in vitro and in vivo methods. An in vitro model of intestinal epithelial tissue was created by seeding co-cultures of Caco-2 and HT29-MTX cells on a Transwell permeable support. These experiments were repeated with monolayers that had been cultured with the beneficial commensal bacteria Lactobacillus rhamnosus GG (L. rhamnosus). Glucose uptake and transport in the presence of TiO 2 nanoparticles was assessed using fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG). When the cell monolayers were exposed to physiologically relevant doses of TiO 2 , a statistically significant reduction in glucose transport was observed. These differences in glucose absorption were eliminated in the presence of beneficial bacteria. The decrease in glucose absorption was caused by damage to intestinal microvilli, which decreased the surface area available for absorption. Damage to microvilli was ameliorated in the presence of L. rhamnosus. Complimentary studies in Drosophila melanogaster showed that TiO 2 ingestion resulted in decreased body size and glucose content. The results suggest that TiO 2 nanoparticles alter glucose transport across the intestinal epithelium, and that TiO 2 nanoparticle ingestion may have physiological consequences.

Synthesis of silver-titanium dioxide nanocomposites for antimicrobial applications

NASA Astrophysics Data System (ADS)

Yang, X. H.; Fu, H. T.; Wang, X. C.; Yang, J. L.; Jiang, X. C.; Yu, A. B.

2014-08-01

Silver-titanium dioxide (Ag-TiO2) nanostructures have attracted increasing attention because of unique functional properties and potential applications in many areas such as photocatalysis, antibacterial, and self-cleaning coatings. In this study, Ag@TiO2 core-shell nanostructures and Ag-decorated TiO2 particles (TiO2@Ag) (the size of these two nanoparticles is ranging from 200-300 nm) have been synthesized by a developed facile but efficient method. These two types of hybrid nanostructures, characterized by various advanced techniques (TEM, XRD, BET and others), exhibit unique functional properties particularly in antibacterial toward Gram negative Escherichia coli, as a case study. Specifically: (i) the TiO2@Ag nanoparticles are superior in bacterial growth inhibition in standard culture conditions (37 °C incubator) to the Ag@TiO2 core-shell ones, in which silver may dominate the antibacterial performance; (ii) while after UV irradiation treatment, the Ag@TiO2 core-shell nanoparticles exhibit better performance in killing grown bacteria than the TiO2@Ag ones, probably because of the Ag cores facilitating charge separation for TiO2, and thus produce more hydroxyl radicals on the surface of the TiO2 particles; and (iii) without UV irradiation, both TiO2@Ag and Ag@TiO2 nanostructures show poor capabilities in killing mature bacteria. These findings would be useful for designing hybrid metal oxide nanocomposites with desirable functionalities in bioapplications in terms of sterilization, deodorization, and water purification.

Titanium Dioxide Modulation of the Contractibility of Visceral Smooth Muscles In Vivo

NASA Astrophysics Data System (ADS)

Tsymbalyuk, Olga V.; Naumenko, Anna M.; Rohovtsov, Oleksandr O.; Skoryk, Mykola A.; Voiteshenko, Ivan S.; Skryshevsky, Valeriy A.; Davydovska, Tamara L.

2017-02-01

Electronic scanning microscopy was used in the work to obtain the image and to identify the sizes of titanium dioxide (TiO2) nanoparticles 21 ± 5 nm. The qualitative and quantitative elemental analysis of the preparations of the caecum, antrum, myometrium, kidneys, and lungs of the rats, burdened with titanium dioxide, was also performed. It was established using the tenzometric method in the isometric mode that the accumulation of titanium dioxide in smooth muscles of the caecum resulted in the considerable, compared to the control, increase in the frequency of their spontaneous contractions, the decrease in the duration of the contraction-relaxation cycle, and the decrease in the indices of muscle functioning efficiency (the index of contractions in Montevideo units (MU) and the index of contractions in Alexandria units (AU)). In the same experimental conditions, there was not the increase, but the decrease in the frequency of spontaneous contractions, the duration of the contraction-relaxation cycle, and the increase in MU and AU indices in the smooth muscles of myometrium (in the group of rats, burdened with TiO2 for 30 days). It was also determined that TiO2 modulates both the mechanisms of the input of extracellular Ca2+ ions and the mechanisms of decreasing the concentration of these cations in smooth muscle cells of the caecum during the generation of the high potassium contraction. In these conditions, there is a considerable increase in the normalized maximal velocity of the contraction phase and the relaxation phase. It was demonstrated in the work that titanium dioxide also changes the cholinergic excitation in these muscles. The impact of titanium dioxide in the group of rats, burdened with TiO2, was accompanied with a considerable impairment of the kinetics of forming the tonic component of the oxytocin-induced contraction of the smooth muscles of myometrium.

Acute effects of sono-activated photocatalytic titanium dioxide nanoparticles on oral squamous cell carcinoma.

PubMed

Moosavi Nejad, S; Takahashi, Hiromasa; Hosseini, Hamid; Watanabe, Akiko; Endo, Hitomi; Narihira, Kyoichi; Kikuta, Toshihiro; Tachibana, Katsuro

2016-09-01

Sonodynamic therapy (SDT) is a new treatment modality using ultrasound to activate certain chemical sensitizers for cancer therapy. In this study, effects of high intensity focused ultrasound (HIFU) combined with photocatalytic titanium dioxide (TiO2) nanoparticles on human oral squamous cell line HSC-2 were investigated. Viability of HSC-2 cells after 0, 0.1, 1, or 3s of HIFU irradiation with 20, 32, 55 and 73Wcm(-2) intensities in the presence or absence of TiO2 was measured immediately after the exposures in vitro. Immediate effects of HIFU (3s, 73Wcm(-2)) combined with TiO2 on solid tumors were also examined by histological study. Cytotoxic effect of HIFU+TiO2in vitro was significantly higher than that of TiO2 or HIFU alone with the tendency to increase for higher HIFU intensity, duration, and TiO2 concentration in the suspension. In vivo results showed significant necrosis and tissue damage in HIFU and HIFU+TiO2 treated samples. However, penetration of TiO2 nanoparticles into the cell cytoplasm was only observed in HIFU+TiO2 treated tissues. In this study, our findings provide a rational basis for the development of an effective HIFU based sonodynamic activation method. This approach offers an attractive non-invasive therapy technique for oral cancer in future. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental Study of Acid Treatment Toward Characterization of Structural, Optical, and Morphological Properties of TiO2-SnO2 Composite Thin Film

NASA Astrophysics Data System (ADS)

Fajar, M. N.; Hidayat, R.; Triwikantoro; Endarko

2018-04-01

The TiO2-SnO2 thin film with single and double-layer structure has successfully synthesized on FTO (Fluorine-doped Tin Oxide) substrate using the screen printing technique. The structural, optical, and morphological properties of the film were investigated by XRD, UV-Vis, and SEM, respectively. The results showed that the single and double-layer structure of TiO2-SnO2 thin film has mixed phase with a strong formation of casseritte phase. The acid treatment effect on TiO2-SnO2 thin film decreases the peak intensity of anatase phase formation and thin film’s absorbance values. The morphological study is also revealed that the single layer TiO2-SnO2 thin film had a more porous nature and decreased particle size distribution after acid treatment, while the double-layer TiO2-SnO2 thin film Eroded due to acid treatment.

Broadening the photoresponsive activity of anatase titanium dioxide particles via decoration with partial gold shells.

PubMed

Khantamat, Orawan; Li, Chien-Hung; Liu, Si-Ping; Liu, Tingting; Lee, Han Ju; Zenasni, Oussama; Lee, Tai-Chou; Cai, Chengzhi; Lee, T Randall

2018-03-01

Titanium dioxide (TiO 2 ) has gained increasing interest in materials research due to its outstanding properties and promising applications in a wide range of fields. From this perspective, we report the synthesis of custom-designed anatase TiO 2 submicrometer particles coated with partial Au shells (ATiO 2 -AuShl). The synthetic strategy used herein yields uniformly shaped monodisperse particles. Amorphous TiO 2 core particles were synthesized using template-free oxidation and hydrolysis of titanium nitride (TiN); subsequent hydrothermal treatment generated anatase TiO 2 (ATiO 2 ) particles. Coating ATiO 2 particles with partial Au shells was accomplished using a simple seeded-growth method. Evaluation of the optical properties of these ATiO 2 -AuShl particles showed that these submicrometer composites exhibited an intense absorption peak for TiO 2 in the UV region (∼326 nm) and a broad extinction band in the visible range (∼650 nm) arising from the incomplete Au shell. These ATiO 2 -AuShl composite particles provide a unique and effective means for broadening the optical response of TiO 2 -based nano- and micron-scale materials. The simplicity of our synthetic method should broaden the application of ATiO 2 -AuShl particles in various visible light-driven technologies. Copyright © 2017 Elsevier Inc. All rights reserved.

Improving the activity of rutile titanium dioxide with reduced graphene oxide

NASA Astrophysics Data System (ADS)

Yuliati, Leny; Alim, Nor Shuhada; Lintang, Hendrik O.

2017-11-01

Among titanium dioxide (TiO2), rutile is the most stable polymorph of TiO2 at all temperatures. However, its application as photocatalyst is less explored since generally anatase and anatase-rutile mixture show better photocatalytic activity than the rutile structure. In this study, we successfully improved the photocatalytic activity of rutile up to four times higher when it was modified with reduced graphene oxide (rGO). The rGO-TiO2 composites were prepared by photocatalytic reduction of graphene oxide (GO) at room temperature under ultraviolet (UV) light irradiation in the presence of rutile TiO2. The amount of GO which was prepared by oxidation of graphite flakes via the Hummers' method was varied from 0.5 to 5 wt%. The properties of the obtained composites were investigated by several characterization methods. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopies revealed that the rGO-TiO2 composites could be prepared without disrupting the structure of rutile TiO2. The fluorescence spectroscopy confirmed that the presence of rGO decreased the emission intensity of rutile TiO2, suggesting that the interactions between the rGO and the rutile TiO2 might cause the decrease in electron-hole recombination on the TiO2. The activity of the composites was evaluated for degradation of phenol under UV light irradiation for 3 h. It was observed that the addition of small amount of rGO (1 wt% GO) significantly improved the photocatalytic activity of rutile TiO2.

Toxicity mechanism of titanium dioxide and zinc oxide nanoparticles against food pathogens.

PubMed

Venkatasubbu, G Devanand; Baskar, R; Anusuya, T; Seshan, C Arun; Chelliah, Ramachandran

2016-12-01

Food preservation is an important field of research. It extends the shelf life of major food products. Our current study is based on food preservation through TiO 2 and ZnO nanoparticles. TiO 2 and ZnO are biocompatible nanomaterial. The biocompatibility of the materials were established through toxicity studies on cell lines. Titanium dioxide and Zinc Oxide nanoparticle were synthesized by wet chemical process. They are characterized by X-Ray diffraction and TEM. The antibacterial activities of both the materials were analysed to ensure their effectiveness as food preservative against Salmonella typhi, Klebsiella pneumoniae and Shigella flexneri. The results indicates that TiO 2 and ZnO nanoparticle inhibits Salmonella, Klebsiella and Shigella. The mode of action is by the generation of ROS in cases of Salmonella, Klebsiella. Mode of action in Shigella is still unclear. It was also proved that TiO 2 and ZnO nanoparticle are biocompatible materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Amino acid adsorption on anatase (101) surface at vacuum and aqueous solution: a density functional study.

PubMed

Liu, Liuxie; Li, Kai; Chen, Xiao; Liang, Xiaoqin; Zheng, Yan; Li, Laicai

2018-03-29

The adsorption of 20 amino acids (AAs) on the (101) surface of anatase titanium dioxide (TiO 2 ) has been investigated under the scheme of density functional theory. Through the analysis of adsorption geometries, amino group and side chains of AAs have been identified as the major side to adsorb on TiO 2 , while the carboxyl group prefers to stay outside to avoid the repulsion between negatively charged oxygen from TiO 2 and AAs. On the surface, two-coordinated oxygen is the major site to stabilize AAs through O-H interactions. The above conclusion does not change when it is in the aqueous solution based on the calculations with AAs surrounded by explicit water molecules. The above knowledge is helpful in predicting how AAs and even peptides adsorb on inorganic materials. Graphical abstract The adsorption of 20 amino acids (AAs) on the (101) surface of anatase titanium dioxide (TiO 2 ) has been investigated under the scheme of density functional theory.

Spontaneous Synthesis of Highly Crystalline TiO2 Compact/Mesoporous Stacked Films by a Low-Temperature Steam-Annealing Method for Efficient Perovskite Solar Cells.

PubMed

Sanehira, Yoshitaka; Numata, Youhei; Ikegami, Masashi; Miyasaka, Tsutomu

2018-05-23

Highly crystalline TiO 2 nanostructured films were synthesized by a simple steam treatment of a TiCl 4 precursor film under a saturated water vapor atmosphere at 125 °C, here referred to as the steam-annealing method. In a single TiO 2 film preparation step, a bilayer structure comprising a compact bottom layer and a mesoporous surface layer was formed. The mesoporous layer was occupied by bipyramidal nanoparticles, with a composite phase of anatase and brookite crystals. Despite the low-temperature treatment process, the crystallinity of the TiO 2 film was high, comparable with that of the TiO 2 film sintered at 500 °C. The compact double-layered TiO 2 film was applied to perovskite solar cells (PSCs) as an electron-collecting layer. The PSC exhibited a maximum power conversion efficiency (PCE) of 18.9% with an open-circuit voltage ( V OC ) of 1.15 V. The PCE and V OC were higher than those of PSCs using a TiO 2 film formed by 500 °C sintering.

Influence of different TiO2 blocking films on the photovoltaic performance of perovskite solar cells

NASA Astrophysics Data System (ADS)

Zhang, Chenxi; Luo, Yudan; Chen, Xiaohong; Ou-Yang, Wei; Chen, Yiwei; Sun, Zhuo; Huang, Sumei

2016-12-01

Organolead trihalide perovskite materials have been successfully used as light absorbers in efficient photovoltaic (PV) cells. Cell structures based on mesoscopic metal oxides and planar heterojunctions have already demonstrated very impressive and brisk advances, holding great potential to grow into a mature PV technology. High power conversion efficiency (PCE) values have been obtained from the mesoscopic configuration in which a few hundred nano-meter thick mesoporous scaffold (e.g. TiO2 or Al2O3) infiltrated by perovskite absorber was sandwiched between the electron and hole transport layers. A uniform and compact hole-blocking layer is necessary for high efficient perovskite-based thin film solar cells. In this study, we investigated the characteristics of TiO2 compact layer using various methods and its effects on the PV performance of perovskite solar cells. TiO2 compact layer was prepared by a sol-gel method based on titanium isopropoxide and HCl, spin-coating of titanium diisopropoxide bis (acetylacetonate), screen-printing of Dyesol's bocking layer titania paste, and a chemical bath deposition (CBD) technique via hydrolysis of TiCl4, respectively. The morphological and micro-structural properties of the formed compact TiO2 layers were characterized by scanning electronic microscopy and X-ray diffraction. The analyses of devices performance characteristics showed that surface morphologies of TiO2 compact films played a critical role in affecting the efficiencies. The nanocrystalline TiO2 film deposited via the CBD route acts as the most efficient hole-blocking layer and achieves the best performance in perovskite solar cells. The CBD-based TiO2 compact and dense layer offers a small series resistance and a large recombination resistance inside the device, and makes it possible to achieve a high power conversion efficiency of 12.80%.

Photo-induced toxicity of titanium dioxide nanoparticles to Daphnia magna under natural sunlight.

PubMed

Mansfield, C M; Alloy, M M; Hamilton, J; Verbeck, G F; Newton, K; Klaine, S J; Roberts, A P

2015-02-01

Titanium dioxide nanoparticles (TiO2 NP) are one of the most abundantly utilized nanoparticles in the world. Studies have demonstrated the ability of the anatase crystal of TiO2 NP to produce reactive oxygen species (ROS) in the presence of ultraviolet radiation (UVR), a co-exposure likely to occur in aquatic ecosystems. The goal of this study was to examine the photo-induced toxicity of anatase TiO2 NP under natural sunlight to Daphnia magna. D. magna were exposed to a range of UVR intensities and anatase TiO2 concentrations in an outdoor exposure system using the sun as the source of UVR. Different UVR intensities were achieved using UVR opaque and transparent plastics. AnataseTiO2-NP demonstrated the reciprocal relationship seen in other phototoxic compounds such as polycyclic aromatic hydrocarbons (PAHs) at higher UVR treatments. The calculated 8h LC50 of anatase TiO2 NP was 139 ppb under full intensity ambient natural sunlight, 778 ppb under 50% natural sunlight, and >500 ppm under 10% natural sunlight. Mortality was also compared between animals allowed to accumulate a body burden of anatase TiO2 for 1h and organisms whose first exposure to anatase TiO2 aqueous suspensions occurred under UVR. A significantly greater toxic effect was observed in aqueous, low body burden suspensions than that of TiO2 1h body burdens, which is dissimilar from the model presented in PAHs. Anatase TiO2 presents a unique photo-induced toxic model that is different than that of established phototoxic compounds. Copyright © 2014 Elsevier Ltd. All rights reserved.

Facile synthesis of 3D few-layered MoS2 coated TiO2 nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

2015-07-01

Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications.Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications. Electronic supplementary information (ESI) available: Supplementary SEM, TEM, XPS and EIS analyses. See DOI: 10.1039/c5nr03334a

Potential impact of inorganic nanoparticles on macronutrient digestion: titanium dioxide nanoparticles slightly reduce lipid digestion under simulated gastrointestinal conditions.

PubMed

Li, Qian; Li, Ti; Liu, Chengmei; DeLoid, Glen; Pyrgiotakis, Georgios; Demokritou, Philip; Zhang, Ruojie; Xiao, Hang; McClements, David Julian

Titanium dioxide (TiO 2 ) particles are used in some food products to alter their optical properties, such as whiteness or brightness. These additives typically contain a population of TiO 2 nanoparticles (d < 100 nm), which has led to concern about their potential toxicity. The objective of this study was to examine the impact of TiO 2 particles on the gastrointestinal fate of oil-in-water emulsions using a simulated gastrointestinal tract (GIT) that includes mouth, stomach, and small intestine phases. Theoretical predictions suggested that TiO 2 nanoparticles might inhibit lipid digestion through two physicochemical mechanisms: (i) a fraction of the lipase adsorbs to TiO 2 particle surfaces, thereby reducing the amount available to hydrolyze lipid droplets; (ii) some TiO 2 particles adsorb to the surfaces of lipid droplets, thereby reducing the lipid surface area exposed to lipase. The importance of these mechanisms was tested by passing protein-coated lipid droplets (2%, w/w) through the simulated GIT in the absence and presence of TiO 2 (0.5%, w/w) nanoparticles (18 nm) and fine particles (167 nm). Changes in particle characteristics (size, organization, and charge) and lipid digestion were then measured. Both TiO 2 nanoparticles and fine particles had little impact on the aggregation state and charge of the lipid droplets in the different GIT regions, as well as on the rate and extent of lipid digestion. This suggests that the theoretically predicted impact of particle size on lipid digestion was not seen in practice.

Impact of titanium dioxide nanoparticles on the bacterial communities of biological activated carbon filter intended for drinking water treatment.

PubMed

Zhiyuan, Liu; Shuili, Yu; Heedeung, Park; Qingbin, Yuan; Guicai, Liu; Qi, Li

2016-08-01

Titanium dioxide nanoparticles (TiO2 NPs) are inevitably present in the aquatic environment owing to their increasing production and use. However, knowledge of the potential effects of TiO2 NPs on the treatment of drinking water is scarce. Herein, the effects of two types of anatase TiO2 NPs (TP1, 25 nm; TP2, 100 nm) on the bacterial community in a biological activated carbon (BAC) filter were investigated via quantitative polymerase chain reaction (Q-PCR) analysis, ATP quantification, and 454 pyrosequencing analysis. Both TP1 and TP2 significantly inhibited the bacterial ATP level (p < 0.01) and induced a decrease in the abundance of bacterial 16S rDNA gene copies at doses of 0.1 and 100 mg L(-1). Simultaneously, the diversity and evenness of the bacterial communities were considerably reduced. The relative abundances of bacteria annotated to OTUs from Nitrospira class and Betaproteobacteria class decreased upon TiO2 NP treatment, whereas those of Bacilli class and Gammaproteobacteria class increased. TiO2 NP size showed a greater effect on the bacterial composition than did the dose based on Bray-Curtis distances. These findings identified negative effects of TiO2 NPs on the bacterial community in the BAC filter. Given the fact that BAC filters are used widely in drinking water treatment plants, these results suggested a potential threat by TiO2 NP to drinking water treatment system.

The light transmission and distribution in an optical fiber coated with TiO2 particles.

PubMed

Wang, Wen; Ku, Young

2003-03-01

The light delivery and distribution phenomena along the optical fiber coated with the P-25 TiO(2) particles by dipping was investigated. The surface properties (coverage, roughness and thickness) of the TiO(2) layer coated on the optical fiber were characterized by SEM micrographs. For TiO(2) layer prepared from solutions containing less than 20 wt.% of TiO(2) slurry, the thickness of layer was increased linearly with the TiO(2) slurry content in solutions. The UV light intensity transmitted along a TiO(2)-coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around a coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions. Copyright 2002 Elsevier Science Ltd.

Electron Microscopy Characterization of Vanadium Dioxide Thin Films and Nanoparticles

NASA Astrophysics Data System (ADS)

Rivera, Felipe

Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ˜500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.

Virus inactivation by silver doped titanium dioxide nanoparticles for drinking water treatment.

PubMed

Liga, Michael V; Bryant, Erika L; Colvin, Vicki L; Li, Qilin

2011-01-01

Photocatalytic inactivation of viruses and other microorganisms is a promising technology that has been increasingly utilized in recent years. In this study, photocatalytic silver doped titanium dioxide nanoparticles (nAg/TiO(2)) were investigated for their capability of inactivating Bacteriophage MS2 in aqueous media. Nano-sized Ag deposits were formed on two commercial TiO(2) nanopowders using a photochemical reduction method. The MS2 inactivation kinetics of nAg/TiO(2) was compared to the base TiO(2) material and silver ions leached from the catalyst. The inactivation rate of MS2 was enhanced by more than 5 fold depending on the base TiO(2) material, and the inactivation efficiency increased with increasing silver content. The increased production of hydroxyl free radicals was found to be responsible for the enhanced viral inactivation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Critical review of public health regulations of titanium dioxide, a human food additive.

PubMed

Jovanović, Boris

2015-01-01

From 1916 to 2011, an estimated total of 165050000 metric tons of titanium dioxide (TiO2 ) pigment were produced worldwide. Current safety regulations on the usage of the TiO2 pigment as an inactive ingredient additive in human food are based on legislation from 1969 and are arguably outdated. This article compiles new research results to provide fresh data for potential risk reassessment. However, even after 45 years, few scientific research reports have provided truly reliable data. For example, administration of very high doses of TiO2 is not relevant to daily human uptake. Nevertheless, because dose makes the poison, the literature provides a valuable source for understanding potential TiO2 toxicity after oral ingestion. Numerous scientific articles have observed that TiO2 can pass and be absorbed by the mammalian gastrointestinal tract; can bioconcentrate, bioaccumulate, and biomagnify in the tissues of mammals and other vertebrates; has a very limited elimination rate; and can cause histopathological and physiological changes in various organs of animals. Such action is contrary to the 1969 decision to approve the use of TiO2 as an inactive ingredient in human food without an established acceptable daily intake, stating that neither significant absorption nor tissue storage following ingestion of TiO2 was possible. Thus, relevant governmental agencies should reassess the safety of TiO2 as an additive in human food and consider establishing an acceptable maximum daily intake as a precautionary measure. © 2014 The Author. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.

A comparative study between titania and zirconia as material for scattering layer in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Nursam, N. M.; Hidayat, J.; Shobih; Rosa, E. S.; Pranoto, L. M.

2018-04-01

The photoanode of dye-sensitized solar cells (DSSC) is typically composed of nanocrystalline titania (TiO2) layer that has been sensitized with light-absorbing dye molecules. Large portion of the light, however, could not be efficiently absorbed due to some physical reasons, such as TiO2 crystal size (typically 10-25 nm) that makes the photoanode remains partially transparent to the visible region in the solar spectrum. One of the ways to improve the light harvesting efficiency in DSSC could be achieved by employing an additional scattering layer over the TiO2 electron transport material. In this contribution, we evaluate the effect of light scattering properties on the performance of DSSC. Specifically, the light scattering properties provided from two different scattering materials, i.e. additional TiO2 scattering layer and zirconia (ZrO2) scattering layer, were compared. Both layers were deposited using screen printing technique under the same condition on top of 8 µm thick TiO2 photoanode layer. All samples subsequently received the same thermal annealing treatment at 500 °C and sensitized with ruthenium-based synthetic dyes. Our results revealed that the thickness of the scattering layer for both TiO2 and ZrO2 had a significant effect on the solar cell performance. The best photoconversion efficiency was achieved by samples that were coated with one screen-printing cycle, giving an overall efficiency of 3.50 % and 4.02% for TiO2 and ZrO2, respectively.

Adsorption performance of titanium dioxide (TiO2) coated air filters for volatile organic compounds.

PubMed

Zhong, Lexuan; Lee, Chang-Seo; Haghighat, Fariborz

2012-12-01

The photocatalytic oxidation (PCO) technology as an alternative method for air purification has been studied for decades and a variety of PCO models indicate that the adsorption of reactants on the catalyst surface is one of the major physical and chemical processes occurring at a heterogeneous photocatalytic reaction. However, limited study explored the adsorption effect of a photocatalyst. This study carried out a systematic evaluation of adsorption performance of titanium dioxide (TiO(2)) coated fiberglass fibers (FGFs), TiO(2) coated carbon cloth fibers (CCFs), and original CCFs air filters at various relative humidity conditions for nine volatile organic compounds. TiO(2)/FGFs, TiO(2)/CCFs, and CCFs were characterized by SEM for morphology and N(2) adsorption isotherm for BET surface area and pore structure. A bench-scale adsorption test setup was constructed and adsorption tests were performed at various relative humidity conditions and four different injected concentrations for each compound. The isothermal adsorption curves at low concentration levels were obtained and they were well described by Langmuir isotherm model. It was noticed that there were significant differences between the adsorption behaviors and photocatalytic activities of TiO(2)/FGFs and TiO(2)/CCFs. It was concluded that adsorption performance is closely related to the characteristics of substrates and therefore, the development of a substrate with high adsorption ability is a promising trend for improving the performance of the UV-PCO technology. Copyright © 2012 Elsevier B.V. All rights reserved.

A Triple Functional Approach To Simultaneously Determine the Type, Concentration, and Size of Titanium Dioxide Particles.

PubMed

Zhao, Bin; Yang, Tianxi; Zhang, Zhiyun; Hickey, Michael E; He, Lili

2018-03-06

The large-scale manufacturing and use of titanium dioxide (TiO 2 ) particles in food and consumer products significantly increase the likelihood of human exposure and release into the environment. We present a simple and innovative approach to rapidly identify the type (anatase or rutile), as well as to estimate, the size and concentration of TiO 2 particles using Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS). The identification and discrimination of rutile and anatase were based on their intrinsic Raman signatures. The concentration of the TiO 2 particles was determined based on Raman peak intensity. Particle sizes were estimated based on the ratio between the Raman intensity of TiO 2 and the SERS intensity of myricetin bound to the nanoparticles (NPs), which was proven to be independent of TiO 2 nanoparticle concentrations. The ratio that was calculated from the 100 nm particles was used as a cutoff value when estimating the presence of nanosized particles within a mixture. We also demonstrated the practical use of this approach when determining the type, concentration, and size of E171: a mixture that contains TiO 2 particles of various sizes which are commonly used in many food products as food additives. The presence of TiO 2 anatase NPs in E171 was confirmed using the developed approach and was validated by transmission electron micrographs. TiO 2 presence in pond water was also demonstrated to be an analytical capability of this method. Our approach shows great promise for the rapid screening of nanosized rutile and anatase TiO 2 particles in complex matrixes. This approach will strongly improve the measurement of TiO 2 quality during production, as well as the survey capacity and risk assessment of TiO 2 NPs in food, consumer goods, and environmental samples.

Effects of TiO2 electron blocking layer on photovoltaic performance of photo-electrochemical cell

NASA Astrophysics Data System (ADS)

Bin, Jae-Wook; Kim, Doo-Hwan; Sung, Youl-Moon; Park, Min-Woo

2014-06-01

Dye-sensitized solar cells (DSCs) have used transparent conductive Fluorine-doped SnO2 (FTO) glass/porous TiO2 layer attached using dye molecules/electrolytes (I-/I3-)/Platinium-coated FTO glass configuration. In this work, prior to the coating of nanoporous TiO2 layer on FTO glass, a dense layer of TiO2 film with a thickness of less than ∼100 nm was deposited directly onto the FTO as an electron blocking layer by radio frequency (RF) magnetron sputtering. Under 100 mW/cm2 illumination at AM 1.5, the energy conversion efficiency (η) of the prepared DSC with electron blocking layer of 80 nm thickness was 6.9% (Voc = 0.67 V, Jsc = 12.18 mA/cm2, ff = 0.63), which is increased by 1.3% compared to the typical cell without electron blocking layer.

The role of nanoscale seed layers on the enhanced performance of niobium doped TiO 2 thin films on glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikodemski, Stefan; Dameron, Arrelaine A.; Perkins, John D.

Transparent conducting oxide (TCO) coatings with decreased cost and greater process or performance versatility are needed for a variety of optoelectronic applications. Among potential new TCO candidates, doped titanium dioxide is receiving particular interest. In this study, niobium-doped titania bilayer structures consisting of a nanoscale seed layer (deposited by atomic layer deposition or RF magnetron sputtering) followed by a thick bulk-like layer were grown directly on glass in order to examine the effects of the seed layer processing on the subsequent crystallization and electrical properties of these heterostructures. Observations from Raman spectroscopy suggest that higher oxygen content in the seedmore » layer suppresses the formation of detrimental titania polymorph phases, found in films produced by annealing directly after synthesis without any exposure to oxygen. Here, our results indicate that the generation of excellent Nb:TiO 2 conductors on glass (without breaking vacuum) only occurs within a narrow processing range and that the sequential deposition of oxygen-poor layers on oxygen-rich layers is a critical step towards achieving films with low resistivity.« less

The role of nanoscale seed layers on the enhanced performance of niobium doped TiO 2 thin films on glass

DOE PAGES

Nikodemski, Stefan; Dameron, Arrelaine A.; Perkins, John D.; ...

2016-09-09

Transparent conducting oxide (TCO) coatings with decreased cost and greater process or performance versatility are needed for a variety of optoelectronic applications. Among potential new TCO candidates, doped titanium dioxide is receiving particular interest. In this study, niobium-doped titania bilayer structures consisting of a nanoscale seed layer (deposited by atomic layer deposition or RF magnetron sputtering) followed by a thick bulk-like layer were grown directly on glass in order to examine the effects of the seed layer processing on the subsequent crystallization and electrical properties of these heterostructures. Observations from Raman spectroscopy suggest that higher oxygen content in the seedmore » layer suppresses the formation of detrimental titania polymorph phases, found in films produced by annealing directly after synthesis without any exposure to oxygen. Here, our results indicate that the generation of excellent Nb:TiO 2 conductors on glass (without breaking vacuum) only occurs within a narrow processing range and that the sequential deposition of oxygen-poor layers on oxygen-rich layers is a critical step towards achieving films with low resistivity.« less

Dripping and evolution behavior of primary slag bearing TiO2 through the coke packed bed in a blast-furnace hearth

NASA Astrophysics Data System (ADS)

Liu, Yan-xiang; Zhang, Jian-liang; Wang, Zhi-yu; Jiao, Ke-xin; Zhang, Guo-hua; Chou, Kuo-chih

2017-02-01

To investigate the flow of primary slag bearing TiO2 in the cohesive zone of blast furnaces, experiments were carried out based on the laboratory-scale packed bed systems. It is concluded that the initial temperature of slag dripping increases with decreasing FeO content and increasing TiO2 content. The slag holdup decreases when the FeO content is in the range of 5wt%-10wt%, whereas it increases when the FeO content exceeds 10wt%. Meanwhile, the slag holdup decreases when the TiO2 content increases from 5wt% to 10wt% but increases when the TiO2 content exceeds 10wt%. Moreover, slag/coke interface analysis shows that the reaction between FeO and TiO2 occurs between the slag and the coke. The slag/coke interface is divided into three layers: slag layer, iron-rich layer, and coke layer. TiO2 in the slag is reduced by carbon, and the generated Ti diffuses into iron.

Effect of TiO2 nano fillers on the electrical conductivity of PSAN/TiO2 polymer nanocomposites

NASA Astrophysics Data System (ADS)

Ningaraju, S.; Munirathnamma, L. M.; Kumar, K. V. Aneesh; Ravikumar, H. B.

2016-05-01

The microstructural characterization of Polystyrene co-acrylonitrile and Titanium dioxide (PSAN/TiO2) nanocomposites has been performed by Positron Annihilation Lifetime Spectroscopy. The decrease of positron lifetime parameters viz. o-Ps lifetime (τ3) and free volume size (Vf) up to 0.6 wt% of TiO2 is attributed to the filling of free volume holes by TiO2 nanoparticles. The increased free volume size (Vf) after 0.6 wt% of TiO2 indicates the formation of interface due to TiO2 nanoclusters. The variation of electrical conductivity at the lower and higher concentration of TiO2 in (PSAN/TiO2) nanocomposites is attributed to the blocking effect and space charge effect respectively.

Rational design of a tripartite-layered TiO2 photoelectrode: a candidate for enhanced power conversion efficiency in dye sensitized solar cells.

PubMed

Khan, Javid; Gu, Jiuwang; He, Shiman; Li, Xiaohui; Ahmed, Gulzar; Liu, Zhongwu; Akhtar, Muhammad Nadeem; Mai, Wenjie; Wu, Mingmei

2017-07-20

A tri-layered photoelectrode for dye-sensitized solar cells (DSSCs) is assembled using single crystal hollow TiO 2 nanoparticles (HTNPs), sub-micro hollow TiO 2 mesospheres (SHTMSs) and hierarchical TiO 2 microspheres (HTMSs). The bottom layer composed of single crystal hollow TiO 2 nanoparticles serves to absorb dye molecules, harvest light due to its hollow structure and keep a better mechanical contact with FTO conducting glass; the middle layer consisting of sub-micro hollow mesospheres works as a multifunctional layer due to its high dye adsorption ability, strong light trapping and scattering ability and slow recombination rates; and the top layer consisting of hierarchical microspheres enhances light scattering. The DSSCs made of photoanodes with a tripartite-layer structure (Film 4) show a superior photoconversion efficiency (PCE) of 9.24%, which is 7.4% higher than a single layered photoanode composed of HTNPs (Film 1: 8.90%), 4.6% higher than a double layer-based electrode consisting of HTNPs and SHTMSs (Film 2: 9.03%) and 2.6% higher than a double layer-based electrode made of HTNPs and HTMSs (Film 3: 9.11%). The significant improvements in the PCE for tri-layered TiO 2 photoanodes are mainly because of the combined effects of their higher light scattering ability, long electron lifetime, fast electron transport rate, efficient charge collection and a considerable surface area with high dye-loading capability. This study confirms that the facile tri-layered photoanode is an interesting structure for high-efficiency DSSCs.

Coastal deposits of heavy mineral sands; Global significance and US resources

USGS Publications Warehouse

Van Gosen, Bradley S.; Bleiwas, Donald I.; Bedinger, George M.; Ellefsen, Karl J.; Shah, Anjana K.

2016-01-01

Ancient and modern coastal deposits of heavy mineral sands (HMS) are the principal source of several heavy industrial minerals, with mining and processing operations on every continent except Antarctica. For example, HMS deposits are the main source of titanium feedstock for the titanium dioxide (TiO2) pigments industry, obtained from the minerals ilmenite (Fe2+TiO3), rutile (TiO2) and leucoxene (an alteration product of ilmenite). HMS deposits are also the principal source of zircon (ZrSiO4), from which zirconium dioxide (ZrO2) is obtained for uses mostly in refractory products. Sometimes monazite [(Ce,La,Nd,Th)PO4] is recovered as a byproduct mineral, sought for its rare earth elements and thorium (Ault and others, 2016; Sengupta and Van Gosen, 2016; Van Gosen and Tulsidas, 2016). 

Piper Ornatum and Piper Betle as Organic Dyes for TiO2 and SnO2 Dye Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Hayat, Azwar; Putra, A. Erwin E.; Amaliyah, Novriany; Hayase, Shuzi; Pandey, Shyam. S.

2018-03-01

Dye sensitized solar cell (DSSC) mimics the principle of natural photosynthesis are now currently investigated due to low manufacturing cost as compared to silicon based solar cells. In this report, we utilized Piper ornatum (PO) and Piper betle (PB) as sensitizer to fabricate low cost DSSCs. We compared the photovoltaic performance of both sensitizers with Titanium dioxide (TiO2) and Tin dioxide (SnO2) semiconductors. The results show that PO and PB dyes have higher Short circuit current (Jsc) when applied in SnO2 compared to standard TiO2 photo-anode film even though the Open circuit voltage (Voc) was hampered on SnO2 device. In conclusion, from the result, higher electron injections can be achieved by choosing appropriate semiconductors with band gap that match with dyes energy level as one of strategy for further low cost solar cell.

Efficient in situ synthetic routes of polyaniline/poly(vinyl alcohol)/TiO2 nanocomposites using gamma irradiation

NASA Astrophysics Data System (ADS)

Afify, T. A.; Ghazy, O. A.; Saleh, H. H.; Ali, Z. I.

2018-02-01

Gamma radiation was used to prepare nanocomposites based on polyaniline/titanium dioxide (PANI/TiO2) or polyaniline/poly (vinyl alcohol)/titanium dioxide (PANI/PVA/TiO2). It was found that PANI/TiO2 in the form of nanocomposite as shown by the UV/vis spectroscopy. This was through the appearance and shift of two absorption peaks at 340 and 598 nm. The SEM micrographs of the PANI/TiO2 nanocomposites showed a fibrous morphology before the treatment with HCl. The TiO2 nanoparticles are clearly seen to be precipitated on the PANI fibers and the morphology changed towards the sheets shape with highly distribution on PANI surface. The transmission electron microscopy (TEM) image confirms the fibrous shape of the PANI and spherical shape of TiO2 nanoparticles. The XRD study showed a several diffraction patterns of TiO2 nanoparticles confirming the PANI/TiO2 and PANI/PVA/TiO2 nanocomposites. The FT-IR analysis indicated that there is an interfacial interaction existed between the PANI and its inorganic counterpart of TiO2 nanoparticles. The dielectric constant of the PANI/PVA showed the lowest values and was increased by either doping with TiO2 or increasing irradiation dose.

Photodeposition of Gold, Platinum, or Silver onto Titanium Dioxide Nanoparticles at Steps of Highly Oriented Pyrolytic Graphite

NASA Astrophysics Data System (ADS)

Taing, James

The photodeposition of gold, platinum, or silver nanoparticles selectively onto isolated titanium dioxide (TiO2) nanoparticles created metal/TiO2 photocatalysts and heterogeneous catalysts, and validated the photocatalytic property of the semiconductor. The isolated and ordered TiO2 nanoparticles permitted clear observations of the stability, and changes in morphology, of the particles in various experimental conditions. The fabrication of TiO2 nanoparticles at the steps of highly oriented pyrolytic graphite (HOPG), utilizing physical vapor deposition, required heating the graphite substrate to a minimum of 800 °C. The production of a photocurrent, and plating of gold nanoparticles, confirmed the photocatalytic property of the TiO2 nanoparticles on HOPG when utilized as a photoelectrode in a two half-cell setup. Employing sodium chloride (1.0 M) as an electrolyte resulted in an increase/decrease of the photocurrent with the addition of gold cations to the half-cell without/with the TiO2 nanoparticles. A poor distribution of gold nanoparticles, roughly 40-45 nm wide, deposited around few of the TiO2 nanoparticles. A lower concentration of sodium chloride (0.1 M) resulted in a coalescence of Au nanoparticles, roughly 10 nm, around many TiO2 nanoparticles. Using sodium nitrate as an electrolyte resulted in a rapid decay in the photocurrent and a growth of an unidentified material on the TiO2 nanoparticles. The unidentified material hindered the reduction of gold cations introduced midway through the experiment. With gold cations present at the onset of the experiment, disperse gold nanoparticles (˜5-10 nm) deposited around the TiO2 nanoparticles. In the absence of additional electrolyte, many disperse gold nanoparticles less than 5 nm deposited onto the TiO2 nanoparticles. More platinum than gold selectively deposited onto the TiO2 nanoparticles. On the contrary, less silver selectively deposited onto the TiO2 nanoparticles. Scanning electron microscopy and atomic force microscopy determined the morphology and distribution of the TiO2 nanoparticles and metal/TiO 2 nanocomposites. Energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy identified the composition of the materials.

Asymmetric organic-inorganic hybrid membrane formation via block copolymer-nanoparticle co-assembly.

PubMed

Gu, Yibei; Dorin, Rachel M; Wiesner, Ulrich

2013-01-01

A facile method for forming asymmetric organic-inorganic hybrid membranes for selective separation applications is developed. This approach combines co-assembly of block copolymer (BCP) and inorganic nanoparticles (NPs) with non-solvent induced phase separation. The method is successfully applied to two distinct molar mass BCPs with different fractions of titanium dioxide (TiO2) NPs. The resulting hybrid membranes exhibit structural asymmetry with a thin nanoporous surface layer on top of a macroporous fingerlike support layer. Key parameters that dictate membrane surface morphology include the fraction of inorganics used and the length of time allowed for surface layer development. The resulting membranes exhibit both good selectivity and high permeability (3200 ± 500 Lm(-2) h(-1) bar(-1)). This fast and straightforward synthesis method for asymmetric hybrid membranes provides a new self-assembly platform upon which multifunctional and high-performance organic-inorganic hybrid membranes can be formed.

The effect of humic acid on the aggregation of titanium dioxide nanoparticles under different pH and ionic strengths.

PubMed

Zhu, Miao; Wang, Hongtao; Keller, Arturo A; Wang, Tao; Li, Fengting

2014-07-15

With the increasingly widespread use of titanium dioxide nanoparticles (TiO2 NPs), the particles' environmental impacts have attracted concern, making it necessary to understand the fate and transport of TiO2 NPs in aqueous media. In this study, we investigated TiO2 NP aggregation caused by the effects of humic acid (HA), ionic strength (IS) and different pH using dynamic light scattering (DLS) to monitor the size distribution of the TiO2 NPs continuously. It was determined that HA can influence the stability of TiO2 NPs through charge neutralization, steric hindrance and bridging effects. In the absence of IS, aggregation was promoted by adding HA only when the pH (pH=4) is less than the point of zero charge for the TiO2 NPs (pHPZC≈6) because HA reduces the zeta potential of the TiO2 NPs via charge neutralization. At pH=4 and when the concentration of HA is 94.5 μg/L, the zeta potential of TiO2 NPs is close to zero, and they reach an aggregation maximum. A higher concentration of HA results in more negatively charged TiO2 NP surfaces, which hinder their aggregation. When the pH is 5.8, HA enhances the negative zeta potential of the TiO2 NPs and increases their stability via electrostatic repulsion and steric hindrance. When the pH (pH=8) is greater than pHpzc, the zeta potential of the TiO2 NPs is high (~40 mV), and it barely changes with increasing HA concentration. Thus, the TiO2 NPs are notably stable, and their size does not grow at pH8. The increase in the critical coagulation concentration (CCC) of TiO2 NPs indicated that there is steric hindrance after the addition of HA. HA can enhance the coagulation of TiO2 NPs, primarily due to bridging effect. These findings are useful in understanding the size change of TiO2 NPs, as well as the removal of TiO2 NPs and HA from aqueous media. Copyright © 2014 Elsevier B.V. All rights reserved.

Titanium dioxide nanoparticles activate IL8-related inflammatory pathways in human colonic epithelial Caco-2 cells

NASA Astrophysics Data System (ADS)

Krüger, Kristin; Cossais, François; Neve, Horst; Klempt, Martin

2014-05-01

Nanosized titanium dioxide (TiO2) particles are widely used as food additive or coating material in products of the food and pharmaceutical industry. Studies on various cell lines have shown that TiO2 nanoparticles (NPs) induced the inflammatory response and cytotoxicity. However, the influences of TiO2 NPs' exposure on inflammatory pathways in intestinal epithelial cells and their differentiation have not been investigated so far. This study demonstrates that TiO2 NPs with particle sizes ranging between 5 and 10 nm do not affect enterocyte differentiation but cause an activation of inflammatory pathways in the human colon adenocarcinoma cell line Caco-2. 5 and 10 nm NPs' exposures transiently induce the expression of ICAM1, CCL20, COX2 and IL8, as determined by quantitative PCR, whereas larger particles (490 nm) do not. Further, using nuclear factor (NF)-κB reporter gene assays, we show that NP-induced IL8 mRNA expression occurs, in part, through activation of NF-κB and p38 mitogen-activated protein kinase pathways.

A rapid tool for determination of titanium dioxide content in white chickpea samples.

PubMed

Sezer, Banu; Bilge, Gonca; Berkkan, Aysel; Tamer, Ugur; Hakki Boyaci, Ismail

2018-02-01

Titanium dioxide (TiO 2 ) is a widely used additive in foods. However, in the scientific community there is an ongoing debate on health concerns about TiO 2 . The main goal of this study is to determine TiO 2 content by using laser induced breakdown spectroscopy (LIBS). To this end, different amounts of TiO 2 was added to white chickpeas and analyzed by using LIBS. Calibration curve was obtained by following Ti emissions at 390.11nm for univariate calibration, and partial least square (PLS) calibration curve was obtained by evaluating the whole spectra. The results showed that Ti calibration curve at 390.11nm provides successful determination of Ti level with 0.985 of R 2 and 33.9ppm of limit of detection (LOD) value, while PLS has 0.989 of R 2 and 60.9ppm of LOD. Furthermore, commercial white chickpea samples were used to validate the method, and validation R 2 for simple calibration and PLS were calculated as 0.989 and 0.951, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of protein phosphorylation by monolithic extraction columns based on poly(divinylbenzene) containing embedded titanium dioxide and zirconium dioxide nano-powders.

PubMed

Rainer, Matthias; Sonderegger, Harald; Bakry, Rania; Huck, Christian W; Morandell, Sandra; Huber, Lukas A; Gjerde, Douglas T; Bonn, Günther K

2008-11-01

The potential of an organic monolith with incorporated titanium dioxide (TiO(2)) and zirconium dioxide (ZrO(2)) nanoparticles was evaluated for the selective enrichment of phosphorylated peptides from tryptic digests. A pipette tip was fitted with a monolith based on divinylbenzene (DVB) of highly porous structure, which allows sample to pass through the monolithic bed. The enrichment of phosphopeptides was enhanced by increasing the pipetting cycles during the sample preparation and a higher recovery could be achieved with adequate buffer systems. A complete automated process was developed for enrichment of phosphopeptides leading to high reproducibility and resulting in a robust method designed to minimize analytical variance while providing high sensitivity at high sample throughput. The effect of particle size on the selectivity of phosphopeptides was investigated by comparative studies with nano- and microscale TiO(2) and ZrO(2) powders. Eleven phosphopeptides from alpha-casein digest could be recovered by an optimized mixture of microscale TiO(2)/ZrO(2) particles, whereas nine additional phosphopeptides could be retained by the same mixture of nano-structured material. When compared to conventional immobilized metal-ion affinity chromatography and commercial phosphorylation-enrichment kits, higher selectivity was observed in case of self fabricated tips. About 20 phosphopeptides could be retained from alpha-casein and five from beta-casein digests by using TiO(2) and ZrO(2) based extraction tips. Further selectivity for phosphopeptides was demonstrated by enriching a digest of in vitro phosphorylated extracellular signal regulated kinase 1 (ERK1). Two phosphorylated peptides of ERK1 could be identified by MALDI-MS/MS measurements and a following MASCOT database search.

Toxicogenomics analysis of mouse lung responses following exposure to titanium dioxide nanomaterials reveal their disease potential at high doses

PubMed Central

Rahman, Luna; Wu, Dongmei; Johnston, Michael; William, Andrew; Halappanavar, Sabina

2017-01-01

Titanium dioxide nanoparticles (TiO2NPs) induce lung inflammation in experimental animals. In this study, we conducted a comprehensive toxicogenomic analysis of lung responses in mice exposed to six individual TiO2NPs exhibiting different sizes (8, 20 and 300nm), crystalline structure (anatase, rutile or anatase/rutile) and surface modifications (hydrophobic or hydrophilic) to investigate whether the mechanisms leading to TiO2NP-induced lung inflammation are property specific. A detailed histopathological analysis was conducted to investigate the long-term disease implications of acute exposure to TiO2NPs. C57BL/6 mice were exposed to 18, 54, 162 or 486 µg of TiO2NPs/mouse via single intratracheal instillation. Controls were exposed to dispersion medium only. Bronchoalveolar lavage fluid (BALF) and lung tissue were sampled on 1, 28 and 90 days post-exposure. Although all TiO2NPs induced lung inflammation as measured by the neutrophil influx in BALF, rutile-type TiO2NPs induced higher inflammation with the hydrophilic rutile TiO2NP showing the maximum increase. Accordingly, the rutile TiO2NPs induced higher number of differentially expressed genes. Histopathological analysis of lung sections on Day 90 post-exposure showed increased collagen staining and fibrosis-like changes following exposure to the rutile TiO2NPs at the highest dose tested. Among the anatase, the smallest TiO2NP of 8nm showed the maximum response. The anatase TiO2NP of 300nm was the least responsive of all. The results suggest that the severity of lung inflammation is property specific; however, the underlying mechanisms (genes and pathways perturbed) leading to inflammation were the same for all particle types. While the particle size clearly influenced the overall acute lung responses, a combination of small size, crystalline structure and hydrophilic surface contributed to the long-term pathological effects observed at the highest dose (486 µg/mouse). Although the dose at which the pathological changes were observed is considered physiologically high, the study highlights the disease potential of certain TiO2NPs of specific properties. PMID:27760801

Preparation of anatase TiO2 thin film by low temperature annealing as an electron transport layer in inverted polymer solar cells

NASA Astrophysics Data System (ADS)

Noh, Hongche; Oh, Seong-Geun; Im, Seung Soon

2015-04-01

To prepare the anatase TiO2 thin films on ITO glass, amorphous TiO2 colloidal solution was synthesized through the simple sol-gel method by using titanium (IV) isopropoxide as a precursor. This amorphous TiO2 colloidal solution was spread on ITO glass by spin-coating, then treated at 450 °C to obtain anatase TiO2 film (for device A). For other TiO2 films, amorphous TiO2 colloidal solution was treated through solvothermal process at 180 °C to obtain anatase TiO2 colloidal solution. This anatase TiO2 colloidal solution was spread on ITO glass by spin coating, and then annealed at 200 °C (for device B) and 130 °C (for device C), respectively. The average particle size of amorphous TiO2 colloidal solution was about 1.0 nm and that of anatase TiO2 colloidal solution was 10 nm. The thickness of TiO2 films was about 15 nm for all cases. When inverted polymer solar cells were fabricated by using these TiO2 films as an electron transport layer, the device C showed the highest PCE (2.6%) due to the lack of defect, uniformness and high light absorbance of TiO2 films. The result of this study can be applied for the preparation of inverted polymer solar cell using TiO2 films as a buffer layer at low temperature on plastic substrate by roll-to roll process.

The synergistic effect of nitrogen-doped titanium dioxide/mercaptobenzoic acid/silver nanocomplexes for surface-enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Feng, Jun; Bao, Wenyuan; Li, Lijun; Cheng, Hao; Huang, Wenyi; Kong, Hongxing; Li, Yanqing

2018-03-01

We synthesized titanium dioxide (TiO2) and nitrogen-doped TiO2 nanoparticles (N-TiO2 NPs) via a sol-hydrothermal method using ammonium chloride (NH4Cl) as the nitrogen (N) source. Furthermore, an N-TiO2/4-mercaptobenzoic acid (4-MBA)/silver (Ag) nanocomplex served as an active substrate for surface-enhanced Raman scattering (SERS) and was prepared by self-assembly. During SERS, the Raman signals of 4-MBA of the N-TiO2/MBA/Ag nanocomplexes exhibited higher intensity and sensitivity than pure TiO2/MBA/Ag, with 1% N doping in N-TiO2, producing the strongest Raman signals. We characterized the N-TiO2 hybrid materials by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible diffuse reflectance spectra. N doping did not influence the phase of the TiO2 crystal. The doped N entered into the crystal lattice of the TiO2, replacing some oxygen (O) to form Ti-O-N or Ti-N-O linkage. The results indicated that an appropriate amount of N doping could enhance the SERS performance of the TiO2 SERS substrate via N substitution doping. These doping forms were beneficial to the molecular charge transfer (CT), and this resulted in improved SERS performance for N-doped TiO2 NPs. We attributed this improvement to the formation of N-doping energy levels that were beneficial to the process of TiO2 to MBA molecule CT. This work not only enriched the nonmetal-doped CT mechanism in SERS but also provided several reference values for practical applications. [Figure not available: see fulltext.

Atomic Layer Deposition Al2O3 Coatings Significantly Improve Thermal, Chemical, and Mechanical Stability of Anodic TiO2 Nanotube Layers

PubMed Central

2017-01-01

We report on a very significant enhancement of the thermal, chemical, and mechanical stability of self-organized TiO2 nanotubes layers, provided by thin Al2O3 coatings of different thicknesses prepared by atomic layer deposition (ALD). TiO2 nanotube layers coated with Al2O3 coatings exhibit significantly improved thermal stability as illustrated by the preservation of the nanotubular structure upon annealing treatment at high temperatures (870 °C). In addition, a high anatase content is preserved in the nanotube layers against expectation of the total rutile conversion at such a high temperature. Hardness of the resulting nanotube layers is investigated by nanoindentation measurements and shows strongly improved values compared to uncoated counterparts. Finally, it is demonstrated that Al2O3 coatings guarantee unprecedented chemical stability of TiO2 nanotube layers in harsh environments of concentrated H3PO4 solutions. PMID:28291942

Visible Light-activated TiO2 photocatalytic Films; Synthesis, Characterization and Environmental Application for the Destruction of Microcystin-LR

EPA Science Inventory

Titanium dioxide (TiO2) photocatalysis has become one of the most effective advanced oxidation technologies (AOTs) for the treatment of persistent organic contaminants. To generate hydroxyl radicals, a non-selective, reactive oxidizing species and responsible for the oxidation of...

Silicon Impurity Release and Surface Transformation of TiO2 Anatase and Rutile Nanoparticles in Water Environments

EPA Science Inventory

Surface transformation can affect the stability, reactivity, and toxicity of titanium dioxide (TiO2) nanoparticles (NPs) when released to water environments. Herein, we investigated the release kinetics of Si impurity frequently introduced during NP synthesis and the resulting ef...

Photocatalytic removal of 2,4-dichlorophenoxyacetic acid herbicide on copper oxide/titanium dioxide prepared by co-precipitation method

NASA Astrophysics Data System (ADS)

Lee, Shu Chin; Hasan, Norhasnita; Lintang, Hendrik O.; Shamsuddin, Mustaffa; Yuliati, Leny

2016-02-01

In this work, suppression of the charge recombination on the titanium dioxide (TiO2) was reported by the addition of copper oxide (CuO), which led to a higher activity of TiO2 for removal of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide. A series of CuO/TiO2 with CuO loadings of 0.1-1 wt% was prepared through a co-precipitation method. X-ray diffraction patterns revealed that the presence of CuO could not be detected as the low loading amount of CuO might have good dispersion on the surface of TiO2. Diffuse reflectance UV-visible spectra suggested that low loading amount of CuO did not influence the optical property of TiO2. Fluorescence spectroscopy revealed that TiO2 possessed a dominant emission peak of 407 nm at an excitation wavelength of 218 nm. The increasing loading amount of CuO decreased the emission intensity of TiO2, suggesting the successful reduction of charge recombination. After irradiation under UV light for 1 h, CuO(0.1 wt%)/TiO2 gave the highest percentage removal of the herbicide among the samples. The optimum loading amount of CuOmight improve the charge separation and reduce the electron-hole recombination on TiO2 without blocking the active sites, thus leading to the improved photocatalytic activity. This work showed that CuO/TiO2 is a potential photocatalyst for environmental remediation.

Magnetron sputtering in the creation of photonic nanostructures derived from Sasakia Charonda Formosana-butterfly wings for applied in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Niu, Haihong; Zhou, Ru; Cheng, Cong; Zhang, Gonghai; Hu, Yu; Huang, Bin; Zhang, Shouwei; Shang, Xin; Xia, Mei; Xu, Jinzhang

2016-09-01

Creating new functional materials derived from the structures seen on butterfly wings has achieved interest in a variety of research topics. However, there need a concision approach could result in a high-quality, precise, and convenient process for the fabrication of complex nanostructures replication with unique functionalities based on the butterfly wings. Here we developed a pithy approach based on a magnetron sputtering metal Ti process for biotemplating used to refine hierarchically porous titanium dioxide photonic crystal nanostructures (TiO2sbnd PCN), themselves derived from nanostructures present on the wings of Sasakia Charonda Formosana (S. Charonda) butterflies. For the first time, the TiO2sbnd PCN were deposited on the top of the P25 active layer and were used to fabricate DSSCs as the light-scattering layers of photoanodes with power conversion efficiencies of up to 8.7%. Remarkably, a much enhanced photocurrent density and a prominent photoelectrochemical conversion capability have been achieved, which are exceeding most of the previously reported photoanodes as well as a similar butterflies replication-based device structure. Our study suggests many exciting opportunities of developing artificially engineered butterfly wing-based solar-to-fuel conversion.

Chitosan/titanium dioxide nanocomposite coatings: Rheological behavior and surface application to cellulosic paper.

PubMed

Tang, Yanjun; Hu, Xiulan; Zhang, Xinqi; Guo, Daliang; Zhang, Junhua; Kong, Fangong

2016-10-20

Incorporation of nanofillers into a polymeric matrix has received much attention as a route to reinforced polymer nanocomposites. In the present work, an environmentally friendly chitosan (CTS)/titanium dioxide (TiO2) nanocomposite coating was designed/prepared and subsequently employed for imparting antibacterium and improved mechanical properties to cellulosic paper via surface coating. Effect of TiO2 nanoparticle loadings on the rheological behavior of nanocomposite coatings was investigated. Surface application of CTS/TiO2 nanocomposite coatings to cellulosic paper was performed, and the antibacterial activity and mechanical properties of surface-coated cellulosic paper were examined. Results showed that the increased TiO2 nanoparticle loadings decreased the viscosity and dynamic viscoelasticity of the as-prepared coatings, and improved the antibacterial activity and mechanical properties of surface-coated cellulosic paper. The optimum loading of TiO2 nanoparticles was identified at 10%. This work suggested that CTS/TiO2 nanocomposite coatings may have the potential to be used as a promising antibacterial protective coating for paper packaging. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of the calcination temperature on the photocatalytic efficiency of acidic sol-gel synthesized TiO2 nanoparticles in the degradation of alprazolam.

PubMed

Romeiro, Andreia; Freitas, Diana; Emília Azenha, M; Canle, Moisés; Burrows, Hugh D

2017-06-14

We report a comparative study on the photodegradation of the widely used benzodiazepine psychoactive drug alprazolam (8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine, ALP) using direct photolysis, and titanium dioxide photocatalyzed reaction. Titanium dioxide photocatalysts were prepared as nanoparticles by acidic sol-gel methods, calcined at two different temperatures, and their behavior compared with P25 (Degussa type) TiO 2 . Efficient photodegradation was observed in the photocatalytic process, with over 90% degradation after 90 minutes under optimized conditions. Triazolaminoquinoline, 5-chloro-(5-methyl-4H-1,2,4-triazol-4-yl)benzophenone, triazolbenzophenone, and α-hydroxyalprazolam were identified as the degradation products by fluorescence spectroscopy and HPLC-MS. A comparison with the literature suggests that 8H-alprazolam may also be formed. Good mineralization was observed with TiO 2 photocatalysts. ALP photodegradation with TiO 2 follows pseudo-first order kinetics, with rates depending on the photocatalyst used. The effects of the quantity of the photocatalyst and concentration of alprazolam were studied.

Doping concentration dependence of microstructure and magnetic behaviours in Co-doped TiO2 nanorods

PubMed Central

2014-01-01

Co-doped titanium dioxide (TiO2) nanorods with different doping concentrations were fabricated by a molten salt method. It is found that the morphology of TiO2 changes from nanorods to nanoparticles with increasing doping concentration. The mechanism for the structure and phase evolution is investigated in detail. Undoped TiO2 nanorods show strong ferromagnetism at room temperature, whereas incorporating of Co deteriorates the ferromagnetic ordering. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) results demonstrate that the ferromagnetism is associated with Ti vacancy. PMID:25593558

Interfacial Cation-Defect Charge Dipoles in Stacked TiO2/Al2O3 Gate Dielectrics.

PubMed

Zhang, Liangliang; Janotti, Anderson; Meng, Andrew C; Tang, Kechao; Van de Walle, Chris G; McIntyre, Paul C

2018-02-14

Layered atomic-layer-deposited and forming-gas-annealed TiO 2 /Al 2 O 3 dielectric stacks, with the Al 2 O 3 layer interposed between the TiO 2 and a p-type germanium substrate, are found to exhibit a significant interface charge dipole that causes a ∼-0.2 V shift of the flat-band voltage and suppresses the leakage current density for gate injection of electrons. These effects can be eliminated by the formation of a trilayer dielectric stack, consistent with the cancellation of one TiO 2 /Al 2 O 3 interface dipole by the addition of another dipole of opposite sign. Density functional theory calculations indicate that the observed interface-dependent properties of TiO 2 /Al 2 O 3 dielectric stacks are consistent in sign and magnitude with the predicted behavior of Al Ti and Ti Al point-defect dipoles produced by local intermixing of the Al 2 O 3 /TiO 2 layers across the interface. Evidence for such intermixing is found in both electrical and physical characterization of the gate stacks.

Enhanced electrochemical performance of manganese dioxide spheres deposited on a titanium dioxide nanotube arrays substrate

NASA Astrophysics Data System (ADS)

Zhou, He; Zhang, Yanrong

2014-12-01

The deposition of MnO2 spheres on a TiO2 nanotube arrays substrate are achieved via a sequential chemical bath deposition (SCBD) method for an application of anode materials in supercapacitors. The electrochemical performance of the MnO2-TiO2 composite electrode is observed to show a strong dependence on the MnO2 loading mass, which could be adjusted by repeating the SCBD treatment for several cycles. The optimized doses of MnO2 loaded MnO2-TiO2 and MnO2-Ti samples are compared in terms of their areal capacitance studies and the former is of 175 and 101 mF cm-2 at a scan rate of 10 and 100 mV s-1, respectively, which are 1.52-fold and 1.51-fold of that of the latter sample at corresponding scan rates. The enhancement in areal capacitance has been accounted to the progressive effect of the TiO2 tubular substrate on the capacitive behavior of the loaded MnO2 rather than the different MnO2 loading mass on these two substrates. Impedance analysis reveals this enhanced electrochemical activity is owing to the tubular structure of the TiO2 substrate provides an increased reaction area and facilitates the contact of electrolyte with the active MnO2 material. This work justified the suitability of using the TiO2 nanotube arrays for constructing high-performance supercapacitors.

Effect of the polymeric coating thickness on the photocurrent performance of titanium dioxide nanorod arrays-polyaniline composite-based UV photosensor

NASA Astrophysics Data System (ADS)

Yusoff, M. M.; Mamat, M. H.; Malek, M. F.; Othman, , N.; Ismail, A. S.; Saidi, S. A.; Mohamed, R.; Suriani, A. B.; Khusaimi, Z.; Rusop, M.

2018-05-01

Titanium dioxide (TiO2) nanorod arrays (TNAs) were synthesized and deposited on fluorine tin oxide (FTO)-coated glass substrate using a one-step immersion method in a glass container. The effect of the polymeric coating thickness of p-type polyaniline (PANI) on the n-type TNAs was investigated in the p-n heterojunction photodiode (PD) for the application of ultraviolet (UV) photosensor. The fabricated photosensor demonstrated an increased photocurrent under UV irradiation in correlation with the thickness layer of PANI. The measured UV response showed the highest photocurrent of 0.014 µA at 1.0 V of reverse bias with low dark current under the UV radiation (365 nm, 750 µW/cm2). The thickness of the PANI film improved the photocurrent of the fabricated TNAs/PANI composite-based UV photosensor.

Adjustment of Conduction Band Edge of Compact TiO2 Layer in Perovskite Solar Cells Through TiCl4 Treatment.

PubMed

Murakami, Takurou N; Miyadera, Tetsuhiko; Funaki, Takashi; Cojocaru, Ludmila; Kazaoui, Said; Chikamatsu, Masayuki; Segawa, Hiroshi

2017-10-25

Perovskite solar cells (PSCs) without a mesoporous TiO 2 layer, that is, planar-type PSCs exhibit poorer cell performance as compared to PSCs with a porous TiO 2 layer, owing to inefficient electron transfer from the perovskite layer to the compact TiO 2 layer in the former case. The matching of the conduction band levels of perovskite and the compact TiO 2 layer is thus essential for enhancing PSC performance. In this study, we demonstrate the shifting of the conduction band edge (CBE) of the compact TiO 2 layer through a TiCl 4 treatment, with the aim of improving PSC performance. The CBE of the compact TiO 2 layer was shifted to a higher level through the TiCl 4 treatment and then shifted in the opposite direction, that is, to a lower level, through a subsequent heat treatment. These shifts in the CBE were reflected in the PSC performance. The TiCl 4 -treated PSC showed an increase in the open-circuit voltage of more than 150 mV, as well as a decrease of 100 mV after being heated at 450 °C. On the other hand, the short-circuit current decreased after the treatment but increased after heating at temperatures higher than 300 °C. The treated PSC subjected to subsequent heating at 300 °C exhibited the best performance, with the power conversion efficiency of the PSC being 17% under optimized conditions.

Room-Temperature Processing of TiOx Electron Transporting Layer for Perovskite Solar Cells.

PubMed

Deng, Xiaoyu; Wilkes, George C; Chen, Alexander Z; Prasad, Narasimha S; Gupta, Mool C; Choi, Joshua J

2017-07-20

In order to realize high-throughput roll-to-roll manufacturing of flexible perovskite solar cells, low-temperature processing of all device components must be realized. However, the most commonly used electron transporting layer in high-performance perovskite solar cells is based on TiO 2 thin films processed at high temperature (>450 °C). Here, we demonstrate room temperature solution processing of the TiO x layer that performs as well as the high temperature TiO 2 layer in perovskite solar cells, as evidenced by a champion solar cell efficiency of 16.3%. Using optical spectroscopy, electrical measurements, and X-ray diffraction, we show that the room-temperature processed TiO x is amorphous with organic residues, and yet its optical and electrical properties are on par with the high-temperature TiO 2 . Flexible perovskite solar cells that employ a room-temperature TiO x layer with a power conversion efficiency of 14.3% are demonstrated.

The flavonoid quercetin inhibits titanium dioxide (TiO2)-induced chronic arthritis in mice.

PubMed

Borghi, Sergio M; Mizokami, Sandra S; Pinho-Ribeiro, Felipe A; Fattori, Victor; Crespigio, Jefferson; Clemente-Napimoga, Juliana T; Napimoga, Marcelo H; Pitol, Dimitrius L; Issa, João P M; Fukada, Sandra Y; Casagrande, Rubia; Verri, Waldiceu A

2018-03-01

Titanium dioxide (TiO 2 ) is a common component of orthopedic prosthesis. However, prosthesis wear releases TiO 2 , which induces inflammation and osteolysis in peri-prosthetic tissues. Quercetin is a flavonoid widely present in human diet, which presents biological activities such as antinociceptive, anti-inflammatory and antioxidant effects. Therefore, the effect of intraperitoneal treatment with quercetin in TiO 2 -induced arthritis model was evaluated. In the first set of experiments, mice received injection of TiO 2 (0.1-3 mg/knee joint) and articular mechanical hyperalgesia, edema and histopathology analysis were performed in a 30 days protocol. The dose of 3 mg of TiO 2 showed the most harmful effect, and was chosen to the following experiments. Subsequently, mice received 3 mg of TiO 2 followed by post-treatment with quercetin during 30 days. Quercetin (10-100 mg/kg) inhibited in a dose-dependent manner TiO 2 -induced knee joint mechanical hyperalgesia, edema and leukocyte recruitment and did not induce damage in major organs such as liver, kidney and stomach. The dose of 30 mg/kg was chosen for the subsequent analysis, and reduced histopathological changes such as leukocyte infiltration, vascular proliferation and synovial hyperplasia (pannus formation) on day 30 after TiO 2 challenge. The protective analgesic and anti-inflammatory mechanisms of quercetin included the inhibition of TiO 2 -induced neutrophil and macrophage recruitment, proteoglycan degradation, oxidative stress, cytokine production (TNF-α, IL-1β, IL-6, and IL-10), COX-2 mRNA expression, and bone resorption as well as activation of Nrf2/HO-1 signaling pathway. These results demonstrate the potential therapeutic applicability of the dietary flavonoid quercetin to reduce pain and inflammatory damages associated with prosthesis wear process-induced arthritis. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact of bimetal electrodes on dielectric properties of TiO2 and Al-doped TiO2 films.

PubMed

Kim, Seong Keun; Han, Sora; Jeon, Woojin; Yoon, Jung Ho; Han, Jeong Hwan; Lee, Woongkyu; Hwang, Cheol Seong

2012-09-26

Rutile structured Al-doped TiO(2) (ATO) and TiO(2) films were grown on bimetal electrodes (thin Ru/thick TiN, Pt, and Ir) for high-performance capacitors. The work function of the top Ru layer decreased on TiN and increased on Pt and Ir when it was thinner than ~2 nm, suggesting that the lower metal within the electrodes influences the work function of the very thin Ru layer. The use of the lower electrode with a high work function for bottom electrode eventually improves the leakage current properties of the capacitor at a very thin Ru top layer (≤2 nm) because of the increased Schottky barrier height at the interface between the dielectric and the bottom electrode. The thin Ru layer was necessary to achieve the rutile structured ATO and TiO(2) dielectric films.

Titanium Dioxide Nanoparticles are not Cytotoxic or Clastogenic in Human Skin Cells

PubMed Central

Browning, Cynthia L; The, Therry; Mason, Michael D; Wise, John Pierce

2015-01-01

The application of nanoparticle technology is rapidly expanding. The reduced dimensionality of nanoparticles can give rise to changes in chemical and physical properties, often resulting in altered toxicity. People are exposed dermally to titanium dioxide (TiO2) nanoparticles in industrial and residential settings. The general public is increasingly exposed to these nanoparticles as their use in cosmetics, sunscreens and lotions expands. The toxicity of TiO2 nanoparticles towards human skin cells is unclear and understudied. We used a human skin fibroblast cell line to investigate the cytotoxicity and clastogenicity of TiO2 nanoparticles after 24 h exposure. In a clonogenic survival assay, treatments of 10, 50 and 100 μg/cm2 induced 97.8, 88.8 and 84.7% relative survival, respectively. Clastogenicity was assessed using a chromosomal aberration assay in order to determine whether TiO2 nanoparticles induced serious forms of DNA damage such as chromatid breaks, isochromatid lesions or chromatid exchanges. Treatments of 0, 10, 50 and 100 μg/cm2 induced 3.3, 3.0, 3.0 and 2.7% metaphases with damage, respectively. No isochromatid lesions or chromatid exchanges were detected. These data show that TiO2 nanoparticles are not cytotoxic or clastogenic to human skin cells. PMID:26568896

Titanium Dioxide Nanoparticles are not Cytotoxic or Clastogenic in Human Skin Cells.

PubMed

Browning, Cynthia L; The, Therry; Mason, Michael D; Wise, John Pierce

2014-11-01

The application of nanoparticle technology is rapidly expanding. The reduced dimensionality of nanoparticles can give rise to changes in chemical and physical properties, often resulting in altered toxicity. People are exposed dermally to titanium dioxide (TiO 2 ) nanoparticles in industrial and residential settings. The general public is increasingly exposed to these nanoparticles as their use in cosmetics, sunscreens and lotions expands. The toxicity of TiO 2 nanoparticles towards human skin cells is unclear and understudied. We used a human skin fibroblast cell line to investigate the cytotoxicity and clastogenicity of TiO 2 nanoparticles after 24 h exposure. In a clonogenic survival assay, treatments of 10, 50 and 100 μg/cm 2 induced 97.8, 88.8 and 84.7% relative survival, respectively. Clastogenicity was assessed using a chromosomal aberration assay in order to determine whether TiO 2 nanoparticles induced serious forms of DNA damage such as chromatid breaks, isochromatid lesions or chromatid exchanges. Treatments of 0, 10, 50 and 100 μg/cm 2 induced 3.3, 3.0, 3.0 and 2.7% metaphases with damage, respectively. No isochromatid lesions or chromatid exchanges were detected. These data show that TiO 2 nanoparticles are not cytotoxic or clastogenic to human skin cells.

Absorption, Distribution and Excretion of Four Forms of Titanium Dioxide Pigment in the Rat.

PubMed

Farrell, Thomas P; Magnuson, Berna

2017-08-01

Titanium dioxide (TiO 2 ) is a white color additive that has a long history of global approval and use in food. There is, however, considerable confusion regarding the applicability of the biological effects of novel, engineered, nano-sized forms of TiO 2 developed for nonpigmentary applications to the safety of oral exposure to food grade TiO 2 pigment. The objective of this study was to assess the absorption, distribution, and routes of excretion in rats after oral exposure to food grade TiO 2 . Four different grades of TiO 2 (200 ppm) or control (0 ppm) diets were fed to rats for 7 consecutive days, followed by control diet only for 1, 24, or 72 h. Concentrations of titanium in liver, kidney and muscle were mainly below the limit of detection (<0.1 to < 0.2 mg/kg wet weight); tissue concentrations of titanium above the LOD were in the range of 0.1 to 0.3 mg/kg wet weight for all groups. Whole blood concentrations of titanium were <0.04 mg/L for all groups. Urinary excretion of titanium was equivalent to <2% daily dose/L of urine for all groups and was generally below the limit of quantification (<0.04 mg/L). Feces represented the predominant route of excretion. These results demonstrate that there is no accumulation of titanium in tissues following consumption of diets containing 200 ppm food grade TiO 2 . No differences in systemic absorption of the 4 forms of TiO 2 were observed indicating that the bioavailability of TiO 2 is consistently low for the range of particle sizes and morphologies examined in this study. © 2017 Institute of Food Technologists®.

Optical properties of titanium di-oxide thin films prepared by dip coating method

NASA Astrophysics Data System (ADS)

Biswas, Sayari; Rahman, Kazi Hasibur; Kar, Asit Kumar

2018-05-01

Titanium dioxide (TiO2) thin films were prepared by sol-gel dip coating method on ITO coated glass substrate. The sol was synthesized by hydrothermal method at 90°C. The sol was then used to make TiO2 films by dip coating. After dip coating the rest of the sol was dried at 100°C to make TiO2 powder. Thin films were made by varying the number of dipping cycles and were annealed at 500°C. XRD study was carried out for powder samples that confirms the formation of anatase phase. Transmission spectra of thin films show sharp rise in the violet-ultraviolet transition region and a maximum transmittance of ˜60%. Band gap of the prepared films varies from 3.15 eV to 3.22 eV.

Strong efficiency improvement in dye-sensitized solar cells by novel multi-dimensional TiO2 photoelectrode

NASA Astrophysics Data System (ADS)

Zhao, Fengyang; Ma, Rong; Jiang, Yongjian

2018-03-01

Titanium dioxide (TiO2) based dye-sensitized solar cells (DSSCs) often exhibit superior power conversion performance. Here we report a DSSC with novel hierarchical TiO2 composite structure (TCS) composed of anatase TiO2 micro-spheres and rutile TiO2 nanobelt framework by hydrothermal approach for high-performance. As photoanode, the TCS based DSSC shows a strong efficiency enhancement by 58% compared with Degussa TiO2 (P25)-DSSC (4.33%). The excellent performance is mainly attribute to its special multi-dimensional structures of TiO2: much active sites of 0D nanoparticle with exposed excellent {001} facet, special electronic transmission channel of 1D nanobelt, good dye adsorption capacity of 2D nanosheet and high light scattering ability of 3D micro-spheres. The novel multi-dimensional TCS materials will open up a new avenue to the electronic devices fields.

The potential use of nanosilver-decorated titanium dioxide nanofibers for toxin decomposition with antimicrobial and self-cleaning properties

NASA Astrophysics Data System (ADS)

Srisitthiratkul, Chutima; Pongsorrarith, Voraluck; Intasanta, Narupol

2011-08-01

While chemical and biological attacks pose risk to human health, clean air is of scientific, environmental and physiological concerns. In the present contribution, the potential use of nanosilver-decorated titanium dioxide (TiO 2) nanofibers for toxin decomposition with antimicrobial activity and self-cleaning properties was investigated. Titanium dioxide nanofibers were prepared through sol-gel reaction followed by an electrospinning process. Following the Japan Industrial Standard (JIS) protocol, decompositions of nitrogen oxide (NOx) and volatile organic compound (VOC) by the TiO 2 nanofibers suggested that these materials were capable of air treatment. To further enhance their anti-microbial activity, silver nanoparticles were decorated onto the TiO 2 nanofibers' surfaces via photoreduction of silver ion in the presence of the nanofibers suspension. Furthermore, tests of photocatalytic activity of the samples were performed by photodegrading methylene blue in water. The nanofibrous membranes prepared from these nanofibers showed superhydrophilicity under UV. Finally, the possibility of using these hybrid nanofibers in environmental and hygienic nanofiltration was proposed, where the self-cleaning characteristics was expected to be valuable in maintenance processes.

Effect of solution combusted TiO2 nanopowder within commercial BaTiO3 dielectric layer on the photoelectric properties for AC powder electroluminescence devices.

PubMed

Park, Sung; Choi, Gil Rak; Kim, Youn Cheol; Lee, Jae Chun; Lee, Ju Hyeon

2013-05-01

A unique synthesis method was developed, which is called solution combustion method (SCM). TiO2 nanopowder was synthesized by this method. This SCM TiO2 nanopowder (-35 nm) was added to the dielectric layer of AC powder electroluminescence (EL) device. The dielectric layer was made of commercial BaTiO3 powder (-1.2 microm) and binding polymer. 0, 5, 10 and 15 wt% of SCM TiO2 nanopowder was added to the dielectric layer during fabrication of AC powder EL device respectively. Dielectric constant of these four kinds of dielectric layers was measured. The brightness and current density of AC powder EL device were also measured. When 10 wt% of SCM TiO2 nanopowder was added, dielectric constant and brightness were increased by 30% and 101% respectively. Furthermore, the current density was decreased by 71%. This means that the brightness was double and the power consumption was one third.

New Method of Producing Titanium Carbide, Monoxide, and Dioxide Grains in Laboratory

NASA Astrophysics Data System (ADS)

Kumamoto, Akihito; Kurumada, Mami; Kimura, Yuki; Kaito, Chihiro

By making a carbon rod covered with Ti on the surface without exposure to air, TiC grains less than 10nm in diameter were predominantly produced. The introduction of a small amount of oxygen in Ar gas (partial pressure 1/1000), allowed the continuous formation of TiO2 and TiO-TiC. The infrared spectra of TiO2, TiO, and TiC were measured. An absorption feature attributed to TiO phase in oxidized TiC grains showed a characteristic peak at 14.7 μm.

New Method of Producing Titanium Carbide, Monoxide, and Dioxide Grains in Laboratory

NASA Astrophysics Data System (ADS)

Kumamoto, Akihito; Kurumada, Mami; Kimura, Yuki; Kaito, Chihiro

By making a carbon rod covered with Ti on the surface without exposure to air, TiC grains less than 10 nm in diameter were predominantly produced. The introduction of a small amount of oxygen in Ar gas (partial pressure 1/1000), allowed the continuous formation of TiO2 and TiO-TiC. The infrared spectra of TiO2, TiO, and TiC were measured. An absorption feature attributed to TiO phase in oxidized TiC grains showed a characteristic peak at 14.7 μm.

An enhanced mangiferaindica for dye sensitized solar cell application

NASA Astrophysics Data System (ADS)

Uno, U. E.; Emetere, M. E.; Fadipe, L. A.; Oluranti, Jonathan

2016-02-01

Titanium dioxide (T1O2) is preferred to Zinc oxide as mesoporous oxide layer because it raised the efficiency of DSSCs from 1% to 7%. The chemistry of the process however seem rigorous to allow the light induced electron injection from the adsorbed dye into the nanocrystallites i.e. which renders the TiO2 conductive. The DSSC fabricated consist of 2.25 cm2 active area of titanium dioxide coated on FTO glass (fluorine tin oxide) immersed in ethanol solution of natural dye extracted as an anode (electrode) and counter electrode. These two electrodes were coupled together and the space between them was filled with the Iodolyte AN-50 as solid electrolyte or redox mediator. The photo electrochemical parameters of the dye extracted (Mango fruit Peel) from the results obtained are short circuit current (Isc)= 1.22×10-2, current density (Jsc)=4.07×10-2, open circuit voltage (voc) =0.53V, fill factor (FF) of 0.16 and the overall conversion efficiency (Eff) =0.345%.

Enzymatic recognition of DNA damage induced by UVB-photosensitized titanium dioxide and biological consequences in Saccharomyces cerevisiae: evidence for oxidatively DNA damage generation.

PubMed

Pinto, A Viviana; Deodato, Elder L; Cardoso, Janine S; Oliveira, Eliza F; Machado, Sérgio L; Toma, Helena K; Leitão, Alvaro C; de Pádula, Marcelo

2010-06-01

Although titanium dioxide (TiO(2)) has been considered to be biologically inert, finding use in cosmetics, paints and food colorants, recent reports have demonstrated that when TiO(2) is attained by UVA radiation oxidative genotoxic and cytotoxic effects are observed in living cells. However, data concerning TiO(2)-UVB association is poor, even if UVB radiation represents a major environmental carcinogen. Herein, we investigated DNA damage, repair and mutagenesis induced by TiO(2) associated with UVB irradiation in vitro and in vivo using Saccharomyces cerevisiae model. It was found that TiO(2) plus UVB treatment in plasmid pUC18 generated, in addition to cyclobutane pyrimidine dimers (CPDs), specific damage to guanine residues, such as 8-oxo-7,8-dihydroguanine (8-oxoG) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG), which are characteristic oxidatively generated lesions. In vivo experiments showed that, although the presence of TiO(2) protects yeast cells from UVB cytotoxicity, high mutation frequencies are observed in the wild-type (WT) and in an ogg1 strain (deficient in 8-oxoG and FapyG repair). Indeed, after TiO(2) plus UVB treatment, induced mutagenesis was drastically enhanced in ogg1 cells, indicating that mutagenic DNA lesions are repaired by the Ogg1 protein. This effect could be attenuated by the presence of metallic ion chelators: neocuproine or dipyridyl, which partially block oxidatively generated damage occurring via Fenton reactions. Altogether, the results indicate that TiO(2) plus UVB potentates UVB oxidatively generated damage to DNA, possibly via Fenton reactions involving the production of DNA base damage, such as 8-oxo-7,8-dihydroguanine. Copyright 2010 Elsevier B.V. All rights reserved.

Effects of aqueous suspensions of titanium dioxide nanoparticles on Artemia salina: assessment of nanoparticle aggregation, accumulation and toxicity

PubMed Central

Ates, Mehmet; Daniels, James; Arslan, Zikri; Farah, Ibrahim O.

2012-01-01

Aquatic stability and impact of titanium dioxide nanoparticles (TiO2 NPs, 10-30 nm) was investigated using Artemia salina. Acute exposure was conducted on nauplii (larvae) and adults in seawater in a concentration range from 10 to 100 mg/L TiO2 NPs for 24 h and 96 h. Rapid aggregation occurred in all suspensions of TiO2 NPs to form micrometer size particles. Yet, both nauplii and adults accumulated the aggregates significantly. Average TiO2 content in nauplii ranged from 0.47 to 3.19 mg/g and from 1.29 to 4.43 mg/g in 24 h and 96 h, respectively. Accumulation in adults was higher ranging from 2.30 to 4.19 mg/g and from 4.38 to 6.20 mg/g in 24 h and 96 h, respectively. Phase contrast microscopy images revealed that Artemia were unable to excrete the particles. Thus, the TiO2 aggregates filled inside the guts. No significant mortality or toxicity occurred within 24 h at any dose. Lipid peroxidation levels characterized with malondialdehyde (MDA) concentrations were not statistically different from those of the controls (p>0.05). These results suggested that suspensions of the TiO2 NPs were nontoxic to Artemia, most likely due to the formation of benign TiO2 aggregates in water. In contrast, both mortality and lipid peroxidation increased in extended exposure to 96 h. Highest mortality occurred in 100 mg/L TiO2 NP suspensions; 18% for nauplii and 14% for adults (LC50 > 100 mg/L). These effects were attributed to the particle loading inside the guts leading to oxidative stress as a result of impaired food uptake for a long period of time. PMID:22810381

Titanium dioxide nanoparticles-mediated in vitro cytotoxicity does not induce Hsp70 and Grp78 expression in human bronchial epithelial A549 cells.

PubMed

Aueviriyavit, Sasitorn; Phummiratch, Duangkamol; Kulthong, Kornphimol; Maniratanachote, Rawiwan

2012-10-01

Titanium dioxide nanoparticles (TiO(2)NPs) are increasingly being used in various industrial applications including the production of paper, plastics, cosmetics and paints. With the increasing number of nano-related products, the concern of governments and the general public about the health and environmental risks, especially with regard to occupational and other environmental exposure, are gradually increasing. However, there is insufficient knowledge about the actual affects upon human health and the environment, as well as a lack of suitable biomarkers for assessing TiO(2)NP-induced cytotoxicity. Since the respiratory tract is likely to be the main exposure route of industrial workers to TiO(2)NPs, we investigated the cytotoxicity of the anatase and rutile crystalline forms of TiO(2)NPs in A549 cells, a human alveolar type II-like epithelial cell line. In addition, we evaluated the transcript and protein expression levels of two heat shock protein (HSP) members, Grp78 and Hsp70, to ascertain their suitability as biomarkers of TiO(2)NP-induced toxicity in the respiratory system. Ultrastructural observations confirmed the presence of TiO(2)NPs inside cells. In vitro exposure of A549 cells to the anatase or rutile forms of TiO(2)NPs led to cell death and induced intracellular ROS generation in a dose-dependent manner, as determined by the MTS and dichlorofluorescein (DCF) assays, respectively. In contrast, the transcript and protein expression levels of Hsp70 and Grp78 did not change within the same TiO(2)NPs dose range (25-500 μg/ml). Thus, whilst TiO(2)NPs can cause cytotoxicity in A549 cells, and thus potentially in respiratory cells, Hsp70 and Grp78 are not suitable biomarkers for evaluating the acute toxicological effects of TiO(2)NPs in the respiratory system.

Core-shell carbon nanosphere-TiO2 composite and hollow TiO2 nanospheres prepared by atomic layer deposition

NASA Astrophysics Data System (ADS)

Bakos, L. P.; Justh, N.; Hernádi, K.; Kiss, G.; Réti, B.; Erdélyi, Z.; Parditka, B.; Szilágyi, I. M.

2016-10-01

Core-shell carbon-TiO2 composite and hollow TiO2 nanospheres were prepared using carbon nanospheres as hard-templates, coating them with TiO2 using atomic layer deposition, and subsequent burning out of the carbon cores. The bare carbon, the composite carbon-TiO2 and the hollow TiO2 nanospheres were characterized with TG/DTA-MS, FTIR, XRD and SEM-EDX.

Ammonia Sensing Behaviors of TiO2-PANI/PA6 Composite Nanofibers

PubMed Central

Wang, Qingqing; Dong, Xianjun; Pang, Zengyuan; Du, Yuanzhi; Xia, Xin; Wei, Qufu; Huang, Fenglin

2012-01-01

Titanium dioxide-polyaniline/polyamide 6 (TiO2-PANI/PA6) composite nanofibers were prepared by in situ polymerization of aniline in the presence of PA6 nanofibers and a sputtering-deposition process with a high purity titanium sputtering target. TiO2-PANI/PA6 composite nanofibers and PANI/PA6 composite nanofibers were fabricated for ammonia gas sensing. The ammonia sensing behaviors of the sensors were examined at room temperature. All the results indicated that the ammonia sensing property of TiO2-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO2-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO2 had a great influence on both the morphology and the sensing property of TiO2-PANI/PA6 composite nanofibers. PMID:23235446

Coaxial nanofibers containing TiO2 in the shell for water treatment applications

NASA Astrophysics Data System (ADS)

Kizildag, N.; Geltmeyer, J.; Ucar, N.; De Buysser, K.; De Clerck, K.

2017-10-01

In recent years, the basic electrospinning setup has undergone many modifications carried out to enhance the quality and improve the functionality of the resulting nanofibers. Being one of these modifications, coaxial electrospinning has attracted great attention. It enables to use different materials in nanofiber production and produce multi-layered and functional nanofibers in one step. In this study, TiO2 has been added to the shell layer of coaxial nanofibers to develop functional nanofibers which may be used in water treatment applications. The coaxial nanofibers containing TiO2 in the shell layer are compared to uniaxial nanofibers containing TiO2 in bulk fiber structure, regarding their morphology and photocatalytic activity. Uniform uniaxial and coaxial nanofibers with TiO2 were obtained. The average nanofiber diameter of coaxial nanofibers were higher. Coaxial nanofibers, which contained lower amount of TiO2, displayed similar performance to uniaxial nanofibers with TiO2 in terms of photocatalytic degradation ability against isoproturon.

The influence of CdS intermediate layer on CdSe/CdS co-sensitized free-standing TiO2 nanotube solar cells

NASA Astrophysics Data System (ADS)

Ren, Xuefeng; Yu, Libo; Li, Zhen; Song, Hai; Wang, Qingyun

2018-01-01

We build CdSe quantum dots (QDs) sensitized TiO2 NT solar cells (CdSe/TiO2 solar cells) by successive ionic layer adsorption reaction (SILAR) method on free-standing translucent TiO2 nanotube (NT) film. The best power conversion efficiency (PCE) 0.74% is obtained with CdSe/TiO2 NT solar cells, however, it is very low. Hence, we introduced the CdS QDs layer located between CdSe QDs and TiO2 NT to achieve an enhanced photovoltaic performance. The J-V test results indicated that the insert of CdS intermediate layer yield a significant improvement of PCE to 2.52%. Combining experimental and theoretical analysis, we find that the effects caused by a translucent TiO2 nanotube film, a better lattices match between CdS and TiO2, and a new formed stepwise band edges structure not only improve the light harvesting efficiency but also increase the driving force of electrons, leading to the improvement of photovoltaic performance.

Titanium Dioxide Nanoparticle-Biomolecule Interactions Influence Oral Absorption

PubMed Central

Jo, Mi-Rae; Yu, Jin; Kim, Hyoung-Jun; Song, Jae Ho; Kim, Kyoung-Min; Oh, Jae-Min; Choi, Soo-Jin

2016-01-01

Titanium dioxide (TiO2) nanoparticles (NPs) have been widely applied in various industrial fields, such as electronics, packaging, food, and cosmetics. Accordingly, concerns about the potential toxicity of TiO2 NPs have increased. In order to comprehend their in vivo behavior and potential toxicity, we must evaluate the interactions between TiO2 NPs and biomolecules, which can alter the physicochemical properties and the fate of NPs under physiological conditions. In the present study, in vivo solubility, oral absorption, tissue distribution, and excretion kinetics of food grade TiO2 (f-TiO2) NPs were evaluated following a single-dose oral administration to rats and were compared to those of general grade TiO2 (g-TiO2) NPs. The effect of the interactions between the TiO2 NPs and biomolecules, such as glucose and albumin, on oral absorption was also investigated, with the aim of determining the surface interactions between them. The intestinal transport pathway was also assessed using 3-dimensional culture systems. The results demonstrate that slightly higher oral absorption of f-TiO2 NPs compared to g-TiO2 NPs could be related to their intestinal transport mechanism by microfold (M) cells, however, most of the NPs were eliminated through the feces. Moreover, the biokinetics of f-TiO2 NPs was highly dependent on their interaction with biomolecules, and the dispersibility was affected by modified surface chemistry. PMID:28335354

Titanium dioxide encapsulation of supported Ag nanoparticles on the porous silica bead for increased photocatalytic activity

NASA Astrophysics Data System (ADS)

Liu, Hui; Deng, Lu; Sun, Chaochao; Li, Junqi; Zhu, Zhenfeng

2015-01-01

A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5-10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO2 nanocrystals.

Modification of surfaces of silver nanoparticles for controlled deposition of silicon, manganese, and titanium dioxides

NASA Astrophysics Data System (ADS)

Apostolova, Tzveta; Obreshkov, B. D.; Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Mel'nik, N. N.; Rudenko, A. A.

2018-01-01

In this work we show that nanometric-thick layers of SiO2, MnO2, and TiO2 may be effectively deposited on various silver nanoparticles (including cubic Ag nanoparticles) covered by a very thin (below 0.4 nm) layer of silver sulphide. The background in Raman measurements generated by sulphide-protected Ag nanoparticles is significantly smaller than that for analogous Ag nanoparticles protected by a monolayer formed from alkanethiols - depositing alkanethiols on a surface of anisotropic silver nanoparticles is the current standard method used for protecting a surface of Ag nanoparticles before depositing a layer of silica. Because of significantly smaller generated Raman background, Ag@SiO2 nanostructures with an Ag2S linkage layer between the silver core and the silica shell are very promising low-background electromagnetic nanoresonators for carrying out Raman analysis of various surfaces - especially using what is known as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Sample SHINERS analyses of various surfaces (including pesticide-contaminated surfaces of tomatoes) using cubic-Ag@SiO2 nanoparticles as electromagnetic nanoresonators are also presented.

Influence of multiple light-scattering on TiO2 nanoparticles imbedded into stratum corneum on light transmittance in UV and visible wavelength regions

NASA Astrophysics Data System (ADS)

Popov, Alexey P.; Priezzhev, Alexander V.; Lademann, Jürgen; Myllylä, Risto

2007-05-01

This paper focuses on the simulation of propagation of radiation in UV and visible wavelength regions within a superficial skin layer (stratum corneum, SC) partially filled with titanium dioxide (TiO II) nanoparticles. Volume concentrations of the particles (0.67% - 2.25%) correspond to the maximal concentrations of the considered particles in the frames of independent scattering. Transmittance of 307-, 400-, and 500-nm light through a 20-μm thick SC is calculated. The effect of the TiO II nanoparticles on the contribution of photons undergone different numbers of scattering acts into transmittance is considered. It is shown that administration of the nanoparticles results in the broadening of the distribution of transmitted photons over undergone scattering acts. It also results in the shift of the maximum location of this distribution to larger number of scattering acts for the wavelengths of 400 and 500 nm being the latter the most pronounced. The increase of undergone scattering acts leads to the elongation of photon trajectories within the medium and results in the increase of the diffuse reflected light and the transmittance decrease.

Titanium-dioxide nanotube p-n homojunction diode

NASA Astrophysics Data System (ADS)

Alivov, Yahya; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant

2014-12-01

Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO2) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO2 nanotubes p-n homojunction. This TiO2:N/TiO2:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of -5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

Higher-efficiency photoelectrochemical electrodes of titanium dioxide-based nanoarrays sensitized simultaneously with plasmonic silver nanoparticles and multiple metal sulfides photosensitizers

NASA Astrophysics Data System (ADS)

Guo, Keying; Liu, Zhifeng; Han, Jianhua; Zhang, Xueqi; Li, Yajun; Hong, Tiantian; Zhou, Cailou

2015-07-01

This paper describes a novel design of high-efficiency photoelectrochemical water splitting electrode, i.e., ordered TiO2 nanorod arrays (NRs) sensitized simultaneously with noble metal (Ag), binary metal sulfides (Ag2S) and ternary metal sulfides (Ag3CuS2) multiple photosensitizers for the first time. The TiO2/Ag/Ag2S/Ag3CuS2 NRs heterostructure is successfully synthesized through successive ion layer adsorption and reaction (SILAR) and a simple ion-exchange process based on ionic reaction mechanism. On the basis of an optimal quantity of Ag, Ag2S and Ag3CuS2 nanoparticles, such TiO2/Ag/Ag2S/Ag3CuS2 NRs exhibit a higher photoelectrochemical activity ever reported for TiO2-based nanoarrays in PEC water splitting, the photocurrent density is up to 9.82 mA cm-2 at 0.47 V versus Ag/AgCl, respectively. This novel architecture is able to increase electron collection efficiency and suppress carrier recombination via (i) a higher efficiency of light-harvesting through these multiple photosensitizers (Ag, Ag2S and Ag3CuS2); (ii) the efficient separation of photo-induced electrons and holes due to the direct electrical pathways; (iii) the surface plasmon resonance (SPR) effect of Ag nanoparticles, which enhances the efficient charge separation and high carrier mobility. This work is useful to explore feasible routes to further enhance the performance of oxide semiconductors for PEC water splitting to produce clean H2 energy.

Critical Review of Public Health Regulations of Titanium Dioxide, a Human Food Additive

PubMed Central

Jovanović, Boris

2015-01-01

From 1916 to 2011, an estimated total of 165 050 000 metric tons of titanium dioxide (TiO2) pigment were produced worldwide. Current safety regulations on the usage of the TiO2 pigment as an inactive ingredient additive in human food are based on legislation from 1969 and are arguably outdated. This article compiles new research results to provide fresh data for potential risk reassessment. However, even after 45 years, few scientific research reports have provided truly reliable data. For example, administration of very high doses of TiO2 is not relevant to daily human uptake. Nevertheless, because dose makes the poison, the literature provides a valuable source for understanding potential TiO2 toxicity after oral ingestion. Numerous scientific articles have observed that TiO2 can pass and be absorbed by the mammalian gastrointestinal tract; can bioconcentrate, bioaccumulate, and biomagnify in the tissues of mammals and other vertebrates; has a very limited elimination rate; and can cause histopathological and physiological changes in various organs of animals. Such action is contrary to the 1969 decision to approve the use of TiO2 as an inactive ingredient in human food without an established acceptable daily intake, stating that neither significant absorption nor tissue storage following ingestion of TiO2 was possible. Thus, relevant governmental agencies should reassess the safety of TiO2 as an additive in human food and consider establishing an acceptable maximum daily intake as a precautionary measure. Integr Environ Assess Manag 2015;11:10–20. © 2014 The Author. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:25091211

Characterization of titanium dioxide nanoparticles in food products: analytical methods to define nanoparticles.

PubMed

Peters, Ruud J B; van Bemmel, Greet; Herrera-Rivera, Zahira; Helsper, Hans P F G; Marvin, Hans J P; Weigel, Stefan; Tromp, Peter C; Oomen, Agnes G; Rietveld, Anton G; Bouwmeester, Hans

2014-07-09

Titanium dioxide (TiO2) is a common food additive used to enhance the white color, brightness, and sometimes flavor of a variety of food products. In this study 7 food grade TiO2 materials (E171), 24 food products, and 3 personal care products were investigated for their TiO2 content and the number-based size distribution of TiO2 particles present in these products. Three principally different methods have been used to determine the number-based size distribution of TiO2 particles: electron microscopy, asymmetric flow field-flow fractionation combined with inductively coupled mass spectrometry, and single-particle inductively coupled mass spectrometry. The results show that all E171 materials have similar size distributions with primary particle sizes in the range of 60-300 nm. Depending on the analytical method used, 10-15% of the particles in these materials had sizes below 100 nm. In 24 of the 27 foods and personal care products detectable amounts of titanium were found ranging from 0.02 to 9.0 mg TiO2/g product. The number-based size distributions for TiO2 particles in the food and personal care products showed that 5-10% of the particles in these products had sizes below 100 nm, comparable to that found in the E171 materials. Comparable size distributions were found using the three principally different analytical methods. Although the applied methods are considered state of the art, they showed practical size limits for TiO2 particles in the range of 20-50 nm, which may introduce a significant bias in the size distribution because particles <20 nm are excluded. This shows the inability of current state of the art methods to support the European Union recommendation for the definition of nanomaterials.

A review on potential neurotoxicity of titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Song, Bin; Liu, Jia; Feng, Xiaoli; Wei, Limin; Shao, Longquan

2015-08-01

As the rapid development of nanotechnology in the past three decades, titanium dioxide nanoparticles (TiO2 NPs), for their peculiar physicochemical properties, are widely applied in consumer products, food additives, cosmetics, drug carriers, and so on. However, little is known about their potential exposure and neurotoxic effects. Once NPs are unintentionally exposed to human beings, they could be absorbed, and then accumulated in the brain regions by passing through the blood-brain barrier (BBB) or through the nose-to-brain pathway, potentially leading to dysfunctions of central nerve system (CNS). Besides, NPs may affect the brain development of embryo by crossing the placental barrier. A few in vivo and in vitro researches have demonstrated that the morphology and function of neuronal or glial cells could be impaired by TiO2 NPs which might induce cell necrosis. Cellular components, such as mitochondrial, lysosome, and cytoskeleton, could also be influenced as well. The recognition ability, spatial memory, and learning ability of TiO2 NPs-treated rodents were significantly impaired, which meant that accumulation of TiO2 NPs in the brain could lead to neurodegeneration. However, conclusions obtained from those studies were not consistent with each other as researchers may choose different experimental parameters, including administration ways, dosage, size, and crystal structure of TiO2 NPs. Therefore, in order to fully understand the potential risks of TiO2 NPs to brain health, figure out research areas where further studies are required, and improve its bio-safety for applications in the near future, how TiO2 NPs interact with the brain is investigated in this review by summarizing the current researches on neurotoxicity induced by TiO2 NPs.

A Molecular Cobalt Catalyst Architected and TiO2 Modified p-GaInP2 Photoelectrode for Hydrogen Production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Jing; Yan, Yong; Young, James

2017-05-01

We demonstrate that by employing a hybrid molecular/semiconductor interface with atomic layer deposited (ALD) TiO2 as an intermediate layer, a robust and corrosion resistant GaInP2-TiO2-cobaltoxime-TiO2 photocathode can be operated in alkaline media (pH =13).

Electron microscopy observation of TiO2 nanocrystal evolution in high-temperature atomic layer deposition.

PubMed

Shi, Jian; Li, Zhaodong; Kvit, Alexander; Krylyuk, Sergiy; Davydov, Albert V; Wang, Xudong

2013-01-01

Understanding the evolution of amorphous and crystalline phases during atomic layer deposition (ALD) is essential for creating high quality dielectrics, multifunctional films/coatings, and predictable surface functionalization. Through comprehensive atomistic electron microscopy study of ALD TiO2 nanostructures at designed growth cycles, we revealed the transformation process and sequence of atom arrangement during TiO2 ALD growth. Evolution of TiO2 nanostructures in ALD was found following a path from amorphous layers to amorphous particles to metastable crystallites and ultimately to stable crystalline forms. Such a phase evolution is a manifestation of the Ostwald-Lussac Law, which governs the advent sequence and amount ratio of different phases in high-temperature TiO2 ALD nanostructures. The amorphous-crystalline mixture also enables a unique anisotropic crystal growth behavior at high temperature forming TiO2 nanorods via the principle of vapor-phase oriented attachment.

[Spectral studies on nano-sized titania photocatalysts prepared by different drying methods].

PubMed

Ye, Zhao; Zhang, Han-hui; Pan, Hai-bo; Pan, Hong-qing

2002-12-01

Nano-sized TiO2 photocatalysts were prepared by drying the ethanol gel of titanium tetrabutoxide through natural state, supercritical ethanol, supercritical carbon dioxide drying methods and characterized by XRD, FTIR spectroscopy, FT-Raman spectroscopy and fluorescent spectroscopy, respectively. We regard degradation of rhodamine B by photocatalyst as a model reaction, and compare photocatalytic activities of samples obtained. The experimental results show that different drying methods have strong effect on crystal structure, energy band structure, optical adsorption property, surface quality and photocatalytic activity, TiO2 photocatalyst prepared by supercritical carbon dioxide drying method has superior photocatalytic activity.

Impact of Nanoparticles and Natural Organic Matter on the Removal of Organic Pollutants by Activated Carbon Adsorption

EPA Science Inventory

Isotherm experiments evaluating trichloroethylene (TCE) adsorption onto powdered activated carbon (PAC) were conducted in the presence and absence of three commercially available nanomaterials— iron oxide (Fe2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2). Isotherm exp...

Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

PubMed

Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

2016-07-20

In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability.

Sol-Gel Deposited Double Layer TiO₂ and Al₂O₃ Anti-Reflection Coating for Silicon Solar Cell.

PubMed

Jung, Jinsu; Jannat, Azmira; Akhtar, M Shaheer; Yang, O-Bong

2018-02-01

In this work, the deposition of double layer ARC on p-type Si solar cells was carried out by simple spin coating using sol-gel derived Al2O3 and TiO2 precursors for the fabrication of crystalline Si solar cells. The first ARC layer was created by freshly prepared sol-gel derived Al2O3 precursor using spin coating technique and then second ARC layer of TiO2 was deposited with sol-gel derived TiO2 precursor, which was finally annealed at 400 °C. The double layer Al2O3/TiO2 ARC on Si wafer exhibited the low average reflectance of 4.74% in the wavelength range of 400 and 1000 nm. The fabricated solar cells based on double TiO2/Al2O3 ARC attained the conversion efficiency of ~13.95% with short circuit current (JSC) of 35.27 mA/cm2, open circuit voltage (VOC) of 593.35 mV and fill factor (FF) of 66.67%. Moreover, the fabricated solar cells presented relatively low series resistance (Rs) as compared to single layer ARCs, resulting in the high VOC and FF.

Defective TiO2 with oxygen vacancies: synthesis, properties and photocatalytic applications

NASA Astrophysics Data System (ADS)

Pan, Xiaoyang; Yang, Min-Quan; Fu, Xianzhi; Zhang, Nan; Xu, Yi-Jun

2013-04-01

Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications.Titanium dioxide (TiO2), as an important semiconductor metal oxide, has been widely investigated in the field of photocatalysis. The properties of TiO2, including its light absorption, charge transport and surface adsorption, are closely related to its defect disorder, which in turn plays a significant role in the photocatalytic performance of TiO2. Among all the defects identified in TiO2, oxygen vacancy is one of the most important and is supposed to be the prevalent defect in many metal oxides, which has been widely investigated both by theoretical calculations and experimental characterizations. Here, we give a short review on the existing strategies for the synthesis of defective TiO2 with oxygen vacancies, and the defect related properties of TiO2 including structural, electronic, optical, dissociative adsorption and reductive properties, which are intimately related to the photocatalytic performance of TiO2. In particular, photocatalytic applications with regard to defective TiO2 are outlined. In addition, we offer some perspectives on the challenge and new direction for future research in this field. We hope that this tutorial minireview would provide some useful contribution to the future design and fabrication of defective semiconductor-based nanomaterials for diverse photocatalytic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00476g

The influence of anatase-rutile mixed phase and ZnO blocking layer on dye-sensitized solar cells based on TiO2nanofiberphotoanodes

PubMed Central

2013-01-01

High performance is expected in dye-sensitized solar cells (DSSCs) that utilize one-dimensional (1-D) TiO2 nanostructures owing to the effective electron transport. However, due to the low dye adsorption, mainly because of their smooth surfaces, 1-D TiO2 DSSCs show relatively lower efficiencies than nanoparticle-based ones. Herein, we demonstrate a very simple approach using thick TiO2 electrospun nanofiber films as photoanodes to obtain high conversion efficiency. To improve the performance of the DSCCs, anatase-rutile mixed-phase TiO2 nanofibers are achieved by increasing sintering temperature above 500°C, and very thin ZnO films are deposited by atomic layer deposition (ALD) method as blocking layers. With approximately 40-μm-thick mixed-phase (approximately 15.6 wt.% rutile) TiO2 nanofiber as photoanode and 15-nm-thick compact ZnO film as a blocking layer in DSSC, the photoelectric conversion efficiency and short-circuit current are measured as 8.01% and 17.3 mA cm−2, respectively. Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy measurements reveal that extremely large electron diffusion length is the key point to support the usage of thick TiO2 nanofibers as photoanodes with very thin ZnO blocking layers to obtain high photocurrents and high conversion efficiencies. PMID:23286741

Potential phototoxicity of aged Al(OH)3-coated Ti02 nanoparticles in retinal pigment epithelial cells

EPA Science Inventory

Titanium dioxide (TiO2) nanoparticles (NPs) exposed to UVA radiation generate reactive oxygen species (ROS). As a component of sunscreen formulations, TiO2 NPs may be coated with Al(OH)3 to prevent ROS from causing oxidative damage to tissues. Simulated swimming pool water (SSPW)...

Photocatalytic inactivation of bacteria from spoiled raw chicken carcasses in aqueous suspensions by TiO2 nanoparticles

USDA-ARS?s Scientific Manuscript database

Bacterial spoilage is a major cause of reduced shelf life of fresh poultry; therefore, decreasing contamination by spoilage bacteria could increase the shelf life of these products. Titanium dioxide (TiO2) nanoparticles in the presence of UVA light possess antibacterial activities towards several ba...

Photocatalytic Destruction of an Organic Dye Using TiO2 and Solar Energy.

ERIC Educational Resources Information Center

Giglio, Kimberly D.; And Others

1995-01-01

Describes a general chemistry experiment that is carried out in sunlight to illustrate the ability of TiO2 to act as a photocatalyst by mineralizing an organic dye into carbon dioxide. Details about the construction of the reactor system used to perform this experiment are included. (DDR)

Growth of ultra-thin TiO 2 films by spray pyrolysis on different substrates

NASA Astrophysics Data System (ADS)

Oja Acik, I.; Junolainen, A.; Mikli, V.; Danilson, M.; Krunks, M.

2009-12-01

In the present study TiO 2 films were deposited by spray pyrolysis method onto ITO covered glass and Si (1 0 0) substrates. The spray solution containing titanium(IV) isopropoxide, acetylacetone and ethanol was sprayed at a substrate temperature of 450 °C employing 1-125 spray pulses (1 s spray and 30 s pause). According to AFM, continuous coverage of ITO and Si substrates with TiO 2 layer is formed by 5-10 and below 5 spray pulses, respectively. XPS studies revealed that TiO 2 film growth on Si substrate using up to 4 spray pulses follows 2D or layer-by-layer-growth. Above 4 spray pulses, 3D or island growth becomes dominant irrespective of the substrate. Only 50 spray pulses result in TiO 2 layer with the thickness more than XPS measurement escape depth as any signal from the substrate could not be detected. TiO 2 grain size remains 30 nm on ITO and increases from 10-20 nm to 50-100 nm on Si substrate with the number of spray pulses from 1 to 125.

Layer-by-layer assembly of TiO(2) colloids onto diatomite to build hierarchical porous materials.

PubMed

Jia, Yuxin; Han, Wei; Xiong, Guoxing; Yang, Weishen

2008-07-15

TiO(2) colloids with the most probably particle size of 10 nm were deposited on the surface of macroporous diatomite by a layer-by-layer (LBL) assembly method with using phytic acid as molecular binder. For preparation of colloidal TiO(2), titanium(IV) isopropoxide (Ti(C(3)H(7)O)(4)) was used as titanium precursor, nitric acid (HNO(3)) as peptizing agent and deionized water and isopropanol (C(3)H(7)OH) as solvent. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N(2) adsorption-desorption, and UV-vis spectra are used to assess the morphology and physical chemistry properties of the resulting TiO(2) coated diatomite. It was shown that the mesoporosity has been introduced into macroporous diatomite by LBL deposition. The mesoporosity was originated from close-packing of the uniform TiO(2) nanoparticles. More TiO(2) could be coated on the surface of diatomite by increasing the deposition cycles. This hierarchical porous material has potential for applications in catalytic reactions involved diffusion limit, especially in photocatalytic reactions.

Titanium dioxide nanoparticles stimulate sea urchin immune cell phagocytic activity involving TLR/p38 MAPK-mediated signalling pathway

PubMed Central

Pinsino, Annalisa; Russo, Roberta; Bonaventura, Rosa; Brunelli, Andrea; Marcomini, Antonio; Matranga, Valeria

2015-01-01

Titanium dioxide nanoparticles (TiO2NPs) are one of the most widespread-engineered particles in use for drug delivery, cosmetics, and electronics. However, TiO2NP safety is still an open issue, even for ethical reasons. In this work, we investigated the sea urchin Paracentrotus lividus immune cell model as a proxy to humans, to elucidate a potential pathway that can be involved in the persistent TiO2NP-immune cell interaction in vivo. Morphology, phagocytic ability, changes in activation/inactivation of a few mitogen-activated protein kinases (p38 MAPK, ERK), variations of other key proteins triggering immune response (Toll-like receptor 4-like, Heat shock protein 70, Interleukin-6) and modifications in the expression of related immune response genes were investigated. Our findings indicate that TiO2NPs influence the signal transduction downstream targets of p38 MAPK without eliciting an inflammatory response or other harmful effects on biological functions. We strongly recommend sea urchin immune cells as a new powerful model for nano-safety/nano-toxicity investigations without the ethical normative issue. PMID:26412401

Interaction of hydrogen chloride and water with oxide surfaces. III - Titanium dioxide

NASA Technical Reports Server (NTRS)

Siriwardane, R. V.; Wightman, J. P.

1983-01-01

The adsorption of hydrogen chloride and water vapors on five TiO2 powders in both the anatase and rutile crystalline forms was studied as a function of temperature, pressure, and outgas conditions. The adsorbents were characterized utilizing X-ray powder diffraction, scanning electron microscopy, surface area analysis, indicator method, microelectrophoresis, XPS, and infrared spectroscopy. It was found that both outgas temperature and adsorption temperature influenced the adsorption of water vapor on TiO2, while water vapor adsorption on TiO2 was completely reversible. It is argued that the number of hydroxyl groups present on the surface determines the adsorption capacity of water on the different titanium dioxides. It was found that heats of immersion in water were affected significantly by outgas temperature. Hydrogen chloride adsorption isotherms at 30 C measured on TiO2 after outgassing at 100-400 C showed that a part of the total HCl adsorbed was irreversibly adsorbed. The highest HCl adsorption capacity per unit area was exhibited by anatase, while pure rutile exhibited the lowest adsorption capacity.

Efficacy of titanium dioxide nanoparticle spray to disinfect mobile phones used by endodontist: A bacteriological study.

PubMed

Palaniswamy, Udayakumar; Habeeb, Aisha; Mohsin, Mohammed

2018-01-01

The objectives of this study were to determine the bacterial contamination of the mobile phones that were used by the endodontist in comparison with the general dentist and also to determine the usefulness of titanium dioxide nanospray (TiO 2 NS) in mobile phone decontamination. Samples from the 60 mobile phones were taken using moist sterile swabs before, 10 min, and 1 week after the use of TiO 2 NS. Before collection of the swabs, the participants' informed consent was obtained. Samples obtained were cultured on blood agar to identify bacterial isolates. All 60 mobile phone cultures were found to be culture positive. There was a significant reduction in the mean number of colony-forming units after decontamination with TiO 2 NS ( P < 0.001). The results from this study showed that the mobile phones may act as an important source of nosocomial pathogens and TiO 2 NS would be an effective decontaminant. Therefore, it is important for dental professionals to practice routine mobile phone disinfection protocol to reduce the chances of occurrence of nosocomial infections.

ALD TiO2 coated silicon nanowires for lithium ion battery anodes with enhanced cycling stability and coulombic efficiency.

PubMed

Memarzadeh Lotfabad, Elmira; Kalisvaart, Peter; Cui, Kai; Kohandehghan, Alireza; Kupsta, Martin; Olsen, Brian; Mitlin, David

2013-08-28

We demonstrate that silicon nanowire (SiNW) Li-ion battery anodes that are conformally coated with TiO2 using atomic layer deposition (ALD) show a remarkable performance improvement. The coulombic efficiency is increased to ∼99%, among the highest ever reported for SiNWs, as compared to 95% for the baseline uncoated samples. The capacity retention after 100 cycles for the nanocomposite is twice as high as that of the baseline at 0.1 C (60% vs. 30%), and more than three times higher at 5 C (34% vs. 10%). We also demonstrate that the microstructure of the coatings is critically important for achieving this effect. Titanium dioxide coatings with an as-deposited anatase structure are nowhere near as effective as amorphous ones, the latter proving much more resistant to delamination from the SiNW core. We use TEM to demonstrate that upon lithiation the amorphous coating develops a highly dispersed nanostructure comprised of crystalline LiTiO2 and a secondary amorphous phase. Electron energy loss spectroscopy (EELS) combined with bulk and surface analytical techniques are employed to highlight the passivating effect of TiO2, which results in significantly fewer cycling-induced electrolyte decomposition products as compared to the bare nanowires.

Titanium dioxide/UV photocatalytic disinfection in fresh carrots.

PubMed

Cho, Mihee; Choi, Yoonjung; Park, Hyojin; Kim, Kwansik; Woo, Gun-Jo; Park, Jiyong

2007-01-01

Increased occurrences of fresh produce-related outbreaks of foodborne illness have focused attention on effective washing processes for fruits and vegetables. A titanium dioxide (TiO2) photocatalytic reaction under UV radiation provides a high rate of disinfection. The photo-killing effects of TiO2 on bacteria in liquid cultures under experimental conditions have been widely studied. However, the disinfection effects of the TiO2 photocatalytic reaction on fresh vegetables during a washing process have not been evaluated. Our objectives were to design a pilot-scale TiO2/UV photocatalytic reactor for fresh carrots and to compare the bactericidal effects of the TiO2/UV reaction against bacteria in liquid media and on carrots. TiO2/UV photocatalytic reactions for 40, 60, and 30 s were required for the complete killing of Escherichia coli, Salmonella Typhimurium, and Bacillus cereus (initial counts of approximately 6.7 log CFU/ml), respectively. The counts of total aerobic bacteria in fresh carrots and foodborne pathogenic bacteria in inoculated carrots were also measured. Counts of total aerobic bacteria were reduced by 1.8 log CFU/g after TiO2/UV photocatalytic disinfection for 20 min compared with a 1.1-log CFU/g reduction by UV alone. E. coli, Salmonella Typhimurium, and B. cereus (8 log CFU/ml) were inoculated onto carrots, and the number of surviving bacteria in carrots was determined after treatment. The TiO2/UV treatment exhibited 2.1-, 2.3-, and 1.8-log CFU/g reductions in the counts of E. coli, Salmonella Typhimurium, and B. cereus, respectively, compared with 1.3-, 1.2-, and 1.2-log CFU/g reductions by UV alone. The TiO2/UV photocatalyst reaction showed significant bactericidal effects, indicating that this process is applicable to nonthermal disinfection of fresh vegetables.

Oral intake of added titanium dioxide and its nanofraction from food products, food supplements and toothpaste by the Dutch population.

PubMed

Rompelberg, Cathy; Heringa, Minne B; van Donkersgoed, Gerda; Drijvers, José; Roos, Agnes; Westenbrink, Susanne; Peters, Ruud; van Bemmel, Greet; Brand, Walter; Oomen, Agnes G

2016-12-01

Titanium dioxide (TiO 2 ) is commonly applied to enhance the white colour and brightness of food products. TiO 2 is also used as white pigment in other products such as toothpaste. A small fraction of the pigment is known to be present as nanoparticles (NPs). Recent studies with TiO 2 NPs indicate that these particles can have toxic effects. In this paper, we aimed to estimate the oral intake of TiO 2 and its NPs from food, food supplements and toothpaste in the Dutch population aged 2 to over 70 years by combining data on food consumption and supplement intake with concentrations of Ti and TiO 2 NPs in food products and supplements. For children aged 2-6 years, additional intake via ingestion of toothpaste was estimated. The mean long-term intake to TiO 2 ranges from 0.06 mg/kg bw/day in elderly (70+), 0.17 mg/kg bw/day for 7-69-year-old people, to 0.67 mg/kg bw/day in children (2-6 year old). The estimated mean intake of TiO 2 NPs ranges from 0.19 μg/kg bw/day in elderly, 0.55 μg/kg bw/day for 7-69-year-old people, to 2.16 μg/kg bw/day in young children. Ninety-fifth percentile (P95) values are 0.74, 1.61 and 4.16 μg/kg bw/day, respectively. The products contributing most to the TiO 2 intake are toothpaste (in young children only), candy, coffee creamer, fine bakery wares and sauces. In a separate publication, the results are used to evaluate whether the presence of TiO 2 NPs in these products can pose a human health risk.

Development of Titanium Dioxide (TiO2 ) Nanocoatings on Food Contact Surfaces and Method to Evaluate Their Durability and Photocatalytic Bactericidal Property.

PubMed

Yemmireddy, Veerachandra K; Farrell, Glenn D; Hung, Yen-Con

2015-08-01

Titanium dioxide (TiO2 ) is a well-known photocatalyst for its excellent bactericidal property under UVA light. The purpose of this study was to develop physically stable TiO2 coatings on food contact surfaces using different binding agents and develop methods to evaluate their durability and microbicidal property. Several types of organic and inorganic binders such as polyvinyl alcohol, polyethylene glycol, polyurethane, polycrylic, sodium and potassium silicates, shellac resin, and other commercial binders were used at 1:1 to 1:16 nanoparticle to binder weight ratios to develop a formulation for TiO2 coating on stainless steel surfaces. Among the tested binders, polyurethane, polycrylic, and shellac resin were found to be physically more stable when used in TiO2 coating at 1:4 to 1:16 weight ratio. The physical stability of TiO2 coatings was determined using adhesion strength and scratch hardness tests by following standard ASTM procedures. Further, wear resistance of the coatings was evaluated based on a simulated cleaning procedure used in food processing environments. TiO2 coating with polyurethane at a 1:8 nanoparticle to binder weight ratio showed the highest scratch hardness (1.08 GPa) followed by coating with polycrylic (0.68 GPa) and shellac (0.14 GPa) binders. Three different techniques, namely direct spreading, glass cover-slip, and indented coupon were compared to determine the photocatalytic bactericidal property of TiO2 coatings against Escherichia coli 0157:H7 at 2 mW/cm(2) UVA light intensity. Under the tested conditions, the indented coupon technique was found to be the most appropriate method to determine the bactericidal property of TiO2 coatings and showed a reduction of 3.5 log CFU/cm(2) in 2 h. © 2015 Institute of Food Technologists®

The Effect of Ambient Titanium Dioxide Microparticle Exposure to the Ocular Surface on the Expression of Inflammatory Cytokines in the Eye and Cervical Lymph Nodes.

PubMed

Eom, Youngsub; Song, Jong Suk; Lee, Hyun Kyu; Kang, Boram; Kim, Hyeon Chang; Lee, Hyung Keun; Kim, Hyo Myung

2016-12-01

To investigate the ocular immune response following exposure to airborne titanium dioxide (TiO2) microparticles. Rats in the TiO2-exposed group (n = 10) were exposed to TiO2 particles for 2 hours twice daily for 5 days, while the controls (n = 10) were not. Corneal staining score and tear lactic dehydrogenase (LDH) activity were measured to evaluate ocular surface damage, serum immunoglobulin (Ig) G and E were assayed by using enzyme-linked immunosorbent assay, and the size of cervical lymph nodes was measured. In addition, the expression of interleukin (IL)-4, IL-17, and interferon (IFN)-γ in the anterior segment of the eyeball and cervical lymph nodes was measured by immunohistochemistry, real-time reverse transcription-polymerase chain reaction (RT-PCR), and Western blot analysis. Median corneal staining score (3.0), tear LDH activity (0.24 optical density [OD]), and cervical lymph node size (36.9 mm2) were significantly higher in the TiO2-exposed group than in the control group (1.0, 0.13 OD, and 26.7 mm2, respectively). Serum IgG and IgE levels were found to be significantly elevated in the TiO2-exposed group (P = 0.021 and P = 0.021, respectively). Interleukin 4 expression was increased in the anterior segment of the eyeball and lymph nodes following TiO2 exposure, as measured by immunostaining, real-time RT-PCR, and Western blot. In addition, IL-17 and IFN-γ levels were also increased following TiO2 exposure compared to controls as measured by immunostaining. Exposure to airborne TiO2 induced ocular surface damage. The Type 2 helper T-cell pathway seems to play a dominant role in the ocular immune response following airborne TiO2 exposure.

Cellular Response to Titanium Dioxide Nanoparticles in Intestinal Epithelial Caco-2 Cells is Dependent on Endocytosis-Associated Structures and Mediated by EGFR

PubMed Central

Krüger, Kristin; Schrader, Katrin; Klempt, Martin

2017-01-01

Titanium dioxide (TiO2) is one of the most applied nanomaterials and widely used in food and non-food industries as an additive or coating material (E171). It has been shown that E171 contains up to 37% particles which are smaller than 100 nm and that TiO2 nanoparticles (NPs) induce cytotoxicity and inflammation. Using a nuclear factor Kappa-light-chain enhancer of activated B cells (NF-κB) reporter cell line (Caco-2nfkb-RE), Real time polymerase chain reaction (PCR), and inhibition of dynamin and clathrin, it was shown that cellular responses induced by 5 nm and 10 nm TiO2 NPs (nominal size) depends on endocytic processes. As endocytosis is often dependent on the epithelial growth factor receptor (EGFR), further investigations focused on the involvement of EGFR in the uptake of TiO2 NPs: (1) inhibition of EGFR reduced inflammatory markers of the cell (i.e., nuclear factor (NF)-κB activity, mRNA of IL8, CCL20, and CXCL10); and (2) exposure of Caco-2 cells to TiO2 NPs activated the intracellular EGFR cascade beginning with EGFR-mediated extracellular signal-regulated kinases (ERK)1/2, and including transcription factor ELK1. This was followed by the expression of ERK1/2 target genes CCL2 and CXCL3. We concluded that TiO2 NPs enter the cell via EGFR-associated endocytosis, followed by activation of the EGFR/ERK/ELK signaling pathway, which finally induces NF-κB. No changes in inflammatory response are observed in Caco-2 cells exposed to 32 nm and 490 nm TiO2 particles. PMID:28387727

Criteria to define a more relevant reference sample of titanium dioxide in the context of food: a multiscale approach.

PubMed

Dudefoi, William; Terrisse, Hélène; Richard-Plouet, Mireille; Gautron, Eric; Popa, Florin; Humbert, Bernard; Ropers, Marie-Hélène

2017-05-01

Titanium dioxide (TiO 2 ) is a transition metal oxide widely used as a white pigment in various applications, including food. Due to the classification of TiO 2 nanoparticles by the International Agency for Research on Cancer as potentially harmful for humans by inhalation, the presence of nanoparticles in food products needed to be confirmed by a set of independent studies. Seven samples of food-grade TiO 2 (E171) were extensively characterised for their size distribution, crystallinity and surface properties by the currently recommended methods. All investigated E171 samples contained a fraction of nanoparticles, however, below the threshold defining the labelling of nanomaterial. On the basis of these results and a statistical analysis, E171 food-grade TiO 2 totally differs from the reference material P25, confirming the few published data on this kind of particle. Therefore, the reference material P25 does not appear to be the most suitable model to study the fate of food-grade TiO 2 in the gastrointestinal tract. The criteria currently to obtain a representative food-grade sample of TiO 2 are the following: (1) crystalline-phase anatase, (2) a powder with an isoelectric point very close to 4.1, (3) a fraction of nanoparticles comprised between 15% and 45%, and (4) a low specific surface area around 10 m 2  g - 1 .

DFT study on the interaction of TiO2 (001) surface with HCHO molecules

NASA Astrophysics Data System (ADS)

Wu, Guofei; Zhao, Cuihua; Guo, Changqing; Chen, Jianhua; Zhang, Yibing; Li, Yuqiong

2018-01-01

The interactions of formaldehyde (HCHO) molecule with TiO2 (001) surface were studied using density functional theory calculations. HCHO molecules are dissociated by the cleavage of Csbnd H bonds after adsorption on TiO2 surface. The strong interactions between HCHO melecules and TiO2 surface are largely attributed to the bonding of hydrogen of HCHO and oxygen of TiO2 surface, which is mainly from the hybridization of the H 1s, O 2p and O 2s. The newly formed Hsbnd O bonds cause the structure changes of TiO2 surface, and lead to the cleavage of Osbnd Ti bond of TiO2 surface. The Csbnd O bond that the dissociated remains of HCHO and newly formed Hsbnd O bond can be oxidized to form carbon dioxide and water in subsequent action by oxygen from the atomosphere. The charges transfer from HCHO to TiO2 surface, and the sum amount of the charges transferred from four HCHO molecules to TiO2 surface is bigger than that from one HCHO molecule to TiO2 surface due to the combined interaction of four HCHO molecules with TiO2 surface.

Titanium dioxide: inhalation toxicology and epidemiology.

PubMed

Hext, Paul M; Tomenson, John A; Thompson, Peter

2005-08-01

Titanium dioxide (TiO(2)) is manufactured worldwide in large quantities for use in a wide range of applications and is normally considered to be toxicologically inert. Findings of tumours in the lungs of rats exposed chronically to high concentrations of TiO(2), but not in similarly exposed mice or hamsters, suggest that the tumorigenic response may be a rat-specific phenomenon but nonetheless raises concerns for potential human health effects. With the limited toxicological understanding of species differences in response to inhaled TiO(2) and a similarly limited amount of epidemiological information with respect to TiO(2) exposure in the workplace, a consortium of TiO(2) manufacturers in Europe (under the European Chemistry Industry Council; CEFIC) and in North America (under the American Chemistry Council; ACC) initiated a programme of research to investigate inter-species differences as a result of exposure to TiO(2) and to conduct detailed epidemiological surveys of the major manufacturing sites. The toxicology studies exposed rats, mice and hamsters to pigment-grade TiO(2) (PG-TiO(2), 0, 10, 50 and 250 mg m(-3)) or ultrafine TiO(2) (UF-TiO(2), 0, 0.5, 2 and 10 mg m(-3)) for 90 days and the lung burdens and tissue responses were evaluated at the end of the exposure period and for up to 1 year after exposure. Results demonstrated clear species differences. Rats and mice had similar lung burdens and clearance rates while hamsters showed high clearance rates. At high lung particle burdens, rats showed a marked progression of histopathological lesions throughout the post-exposure period while mice and hamsters showed minimal initial lesions with recovery apparent during the post-exposure period. Lung neutrophil responses, a sensitive marker of inflammatory changes, reflected the development or recovery of the histopathological lesions. The use of surface area rather than gravimetric lung burden provided closer correlates of the burden to the biological effect across both TiO(2) types. The epidemiological investigations evaluated the mortality statistics at 11 European and 4 US TiO(2) manufacturing plants. They concluded that there was no suggestion of any carcinogenic effect associated with workplace exposure to TiO(2).

Toxicity assessment of anatase and rutile titanium dioxide nanoparticles: The role of degradation in different pH conditions and light exposure.

PubMed

De Matteis, Valeria; Cascione, Mariafrancesca; Brunetti, Virgilio; Toma, Chiara Cristina; Rinaldi, Rosaria

2016-12-01

Titanium dioxide nanoparticles (TiO 2 NPs), in the two crystalline forms, rutile and anatase, have been widely used in many industrial fields, especially in cosmetics. Therefore, a lot of details about their safety issues have been discussed by the scientific community. Many studies have led to a general agreement about TiO 2 NPs toxicity, in particular for anatase form, but no mechanism details have been proved yet. In this study, data confirm the different toxic potential of rutile and anatase TiO 2 NPs in two cell lines up to 5nM nanoparticles concentration. Moreover, we evaluated the role of titanium ions released by TiO 2 NPs in different conditions, at pH=4.5 (the typical lysosomal compartment pH) and at pH=5.5 (the skin physiological pH) in conditions of darkness and light, to mimic the dermal exposure of cosmetics. Anatase nanoparticles were proner to degradation both in the acidic conditions and at skin pH. Our study demonstrates that pH and sunlight are dominant factors to induce oxidative stress, TiO 2 NPs degradation and toxicity effects. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioaccumulation, Sub-acute Toxicity, and Tissue Distribution of Engineered Titanium Dioxide (TiO2) Nanoparticles in Goldfish (Carassius auratus)

PubMed Central

Ates, Mehmet; Demir, Veysel; Adiguzel, Ragip; Arslan, Zikri

2014-01-01

The increased use of nano-sized materials is likely to result in the release of these particles into the environment. It is, however, unclear if these materials are harmful to aquatic animals. In this study, the sub-lethal effects of exposure of low and high concentrations of titanium dioxide nanoparticles (TiO2 NPs) on goldfish (Carassius auratus) were investigated. Tissues, including intestine, gills, muscle, and brain were analyzed for Ti content by ICP-MS. Accumulation of TiO2 NPs increased from 42.71 to 110.68 ppb in the intestine and from 4.10 to 9.86 ppb in the gills of the goldfish with increasing exposure dose from 10 to 100 mg/L TiO2 NPs. No significant accumulation in the muscle and brain of the fish was detected. Malondialdehyde (MDA) as a biomarker of lipid oxidation was detected in the liver of the goldfish. Moreover, TiO2 NPs exposure inhibited growth of the goldfish. Although there was an increase (8.1%) in the body weights of the goldfish for the control group, in the low and high exposure groups 1.8% increase and 19.7 % decrease were measured respectively. PMID:25383077

Characterization of N,C-codoped TiO 2 films prepared by reactive DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Wu, Kee-Rong; Hung, Chung-Hsuang

2009-12-01

Titanium dioxide (TiO 2) films are deposited by codoping nitrogen and carbon on indium tin oxide-coated substrates as visible light (Vis)-enabled catalysts. The X-ray diffraction peak intensity of the preferential orientation in (2 1 1) plane declines when the topmost 1.0 μm layer of the film is ground off. The decrease in the crystallite size and the crystallinity of anatase TiO 2 film is also evidenced by a shift towards the high wave number and broadening of the Raman spectra. Low doping concentrations of N (1.3%) and C (1.8%) are estimated by X-ray photoelectron spectroscopy (XPS) which displays an N 1 s peak at 396.8 eV and a C 1 s peak at 282.1 eV, respectively. This is attributed to the substitution of the oxygen sites with nitrogen and carbon, which is believed to be responsible for the Vis photocatalytic activity into a wavelength of >500 nm. The cross-sectional transmission electron microscopy images show larger pores at the grain boundaries and in larger columnar crystals than in the undoped TiO 2 film. All of these results indicate that porosity, crystallinity and shift in the preferential orientation are more pronounced close to the surface than close to the bottom of the sample. Wettability upon measurement of the water contact angle, methylene blue degradation and radical formation tests under both ultraviolet and Vis irradiation demonstrate that the topmost surface renders not only a larger reactive surface area but also a better carrier transport route than the rest of the film, improving its photocatalytic activity. These results show that surface porosity of the film is dominant than the tailoring of the photocatalytic activities of N,C-codoped TiO 2 catalysts.

Preparation of nanocrystalline TiN coated cubic boron nitride powders by a sol-gel process.

PubMed

Park, Hee S; Umer, M Adeel; Ryu, Ho J; Hong, Soon H

2011-01-01

Cubic boron nitride (cBN) particles coated with 20 wt% nanocrystalline TiN were prepared by coating the surface of cBN particles with TiO2, followed by nitridation with NH3 gas at 900 degrees C. Coating of TiO2 on cBN powders was accomplished by a sol-gel process from a solution of titanium (IV) isopropoxide and anhydrous ethanol. An amorphous TiO(x) layer of 50 nm thickness was homogenously formed on the surface of the cBN particles by the sol-gel process. The amorphous layer was then crystallized to an anatase TiO2 phase through calcination in air at 400 degrees C. The crystallized TiO2 layer was 50 nm in thickness, and the size of TiO2 particles comprising the layer was nearly 10 nm. The TiO2 on cBN surfaces was completely converted into nanocrystalline TiN of uniform particles 20 nm in size on cBN particles by nitridation under flowing NH3 gas.

Exposure assessment of workplace manufacturing titanium dioxide particles

NASA Astrophysics Data System (ADS)

Xu, Huadong; Zhao, Lin; Chen, Zhangjian; Zhou, Jingwen; Tang, Shichuan; Kong, Fanling; Li, Xinwei; Yan, Ling; Zhang, Ji; Jia, Guang

2016-10-01

With the widespread use of titanium dioxide (TiO2) human exposure is inevitable, but the exposure data on TiO2 are still limited. This study adopted off-line filter-based sampling combined with real-time activity-based monitoring to measure the concentrations in a workplace manufacturing TiO2 (primary diameter: 194 ± 108 nm). Mass concentrations (MCs) of aerosol particles in the packaging workshop (total dust: 3.17 mg/m3, nano dust: 1.22 mg/m3) were much higher than those in the milling workshop (total dust: 0.79 mg/m3, nano dust: 0.31 mg/m3) and executive office (total dust: 0.44 mg/m3, nano dust: 0.19 mg/m3). However, the MCs of TiO2 were at a relatively low level in the packaging workshop (total TiO2: 46.4 μg/m3, nano TiO2: 16.7 μg/m3) and milling workshop (total TiO2: 39.4 μg/m3, nano TiO2: 19.4 μg/m3) by ICP-MS. The number concentration (NC), surface area concentration (SAC) of aerosol particles potentially deposited in alveolar (SACA), and tracheobronchial (SACTB) regions of lungs in the packaging workshop were (1.04 ± 0.89) × 105 particles/cm3, 414.49 ± 395.07, and 86.01 ± 83.18 μm2/cm3, respectively, which were all significantly higher than those of the milling workshop [(0.12 ± 0.40) × 105 particles/cm3, 75.38 ± 45.23, and 17.60 ± 9.22 μm2/cm3, respectively] as well as executive office and outdoor background ( p < 0.05). Activity-related characteristics were found in both workshops, and the time-variant characteristics showed very similar trends for 3 days in the packaging workshop. Our study provides important data of TiO2 particles exposure in the workplace.

Enhanced Corrosion Resistance of PVD-CrN Coatings by ALD Sealing Layers

NASA Astrophysics Data System (ADS)

Wan; Zhang, Teng Fei; Ding, Ji Cheng; Kim, Chang-Min; Park, So-Won; Yang, Yang; Kim, Kwang-Ho; Kwon, Se-Hun

2017-04-01

Multilayered hard coatings with a CrN matrix and an Al2O3, TiO2, or nanolaminate-Al2O3/TiO2 sealing layer were designed by a hybrid deposition process combined with physical vapor deposition (PVD) and atomic layer deposition (ALD). The strategy was to utilize ALD thin films as pinhole-free barriers to seal the intrinsic defects to protect the CrN matrix. The influences of the different sealing layers added in the coatings on the microstructure, surface roughness, and corrosion behaviors were investigated. The results indicated that the sealing layer added by ALD significantly decreased the average grain size and improved the corrosion resistance of the CrN coatings. The insertion of the nanolaminate-Al2O3/TiO2 sealing layers resulted in a further increase in corrosion resistance, which was attributed to the synergistic effect of Al2O3 and TiO2, both acting as excellent passivation barriers to the diffusion of corrosive substances.

Optimization of Al2O3/TiO2/Al 2O3 Multilayer Antireflection Coating With X-Ray Scattering Techniques

NASA Astrophysics Data System (ADS)

Li, Chao

Broadband multilayer antireflection coatings (ARCs) are keys to improving solar cell efficiencies. The goal of this dissertation is to optimize the multilayer Al2O3/TiO2/Al2O 3 ARC designed for a III-V space multi-junction solar cell with understanding influences of post-annealing and varying deposition parameters on the optical properties. Accurately measuring optical properties is important in accessing optical performances of ARCs. The multilayer Al2O3/TiO 2/Al2O3 ARC and individual Al2O 3 and TiO2 layers were characterized by a novel X-ray reflectivity (XRR) method and a combined method of grazing-incidence small angle X-ray scattering (GISAXS), atomic force microscopy (AFM), and XRR developed in this study. The novel XRR method combining an enhanced Fourier analysis with specular XRR simulation effectively determines layer thicknesses and surface and interface roughnesses and/or grading with sub-nanometer precision, and densities less than three percent uncertainty. Also, the combined method of GISAXS, AFM, and XRR characterizes the distribution of pore size with one-nanometer uncertainty. Unique to this method, the diffuse scattering from surface and interface roughnesses is estimated with surface parameters (root mean square roughness sigma, lateral correlation length ξ, and Hurst parameter h) obtained from AFM, and layer densities, surface grading and interface roughness/grading obtained from specular XRR. It is then separated from pore scattering. These X-ray scattering techniques obtained consistent results and were validated by other techniques including optical reflectance, spectroscopic ellipsometry (SE), glancing incidence X-ray diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy. The ARCs were deposited by atomic layer deposition with standard parameters at 200 °C. The as-deposited individual Al2O3 layer on Si is porous and amorphous as indicated by the combined methods of GISAXS, AFM, and XRR. Both post-annealing at 400 °C for 40 min in air and varying ALD parameters can eliminate pores, and lead to consistent increases in density and refractive index determined by the XRR method, SE, and optical reflectance measurements. After annealing, the layer remains amorphous. On the other hand, the as-deposited TiO 2 layer is non-porous and amorphous. It is densified and crystallized after annealing at 400 °C for 10 min in air. The multilayer Al2O 3/TiO2/Al2O3 ARC deposited on Si has surface and interface roughnesses and/or grading on the order of one nanometer. Annealing at 400 °C for 10 min in air induces densification and crystallization of the amorphous TiO2 layer as well as possible chemical reactions between TiO2 and Si diffusing from the substrate. On the other hand, Al2O3 layers remain amorphous after annealing. The thickness of the top Al2O3 layer decreases - likely due to interdiffusion between the top two layers and loss of hydrogen from hydroxyl groups initially present in the ALD layers. The thickness of the bottom Al2O3 layer increases, probably due to the diffusion of Si atoms into the bottom layer. In addition, the multilayer Al 2O3/TiO2/Al2O3 ARC was deposited on AlInP (30nm) / GaInP (100nm) / GaAs that includes the topmost layers of III-V multi-junction solar cells. Reflectance below 5 % is achieved within nearly the whole wavelength range of the current-limiting sub-cell. Also, internal scattering occurs in the TiO2 layer possibly associated with the initiated crystallization in the TiO2 layer while absent in the amorphous Al2O3 layers.

Matching characteristics of different buffer layers with VO2 thin films

NASA Astrophysics Data System (ADS)

Yang, Kai; Zhang, Dongping; Liu, Yi; Guan, Tianrui; Qin, Xiaonan; Zhong, Aihua; Cai, Xingmin; Fan, Ping; Lv, Weizhong

2016-10-01

VO2 thin films were fabricated by reactive DC magnetron sputtering on different buffer layers of MgF2, Al2O3 and TiO2, respectively. The crystallinity and orientation relationship, thickness of VO2 thin films, atoms vibrational modes, optical and electrical property, surface morphology of films were characterized by X-ray diffraction, Raman scattering microscopy, step profiler, spectrophotometer, four-probe technique, and scanning electron microscopy, respectively. XRD results investigated that the films have preferential crystalline planes VO2 (011). The crystallinity of VO2 films grown on TiO2 buffer layers are superior to VO2 directly deposited on soda-lime glass. The Raman bands of the VO2 films correspond to an Ag symmetry mode of VO2 (M). The sample prepared on 100nm TiO2 buffer layer appears nanorods structure, and exhibits remarkable solar energy modulation ability as high as 5.82% in full spectrum and 23% in near infrared spectrum. Cross-sectional SEM image of the thin films samples indicate that MgF2 buffer layer has clear interface with VO2 layer. But there are serious interdiffusion phenomenons between Al2O3, TiO2 buffer layer with VO2 layer.

Determination and identification of titanium dioxide nanoparticles in confectionery foods, marketed in South Korea, using inductively coupled plasma optical emission spectrometry and transmission electron microscopy.

PubMed

Kim, Namhoon; Kim, Changkyu; Jung, Soyoung; Park, Youngae; Lee, Youngju; Jo, Juyeon; Hong, Misun; Lee, Sangmi; Oh, Younghee; Jung, Kweon

2018-06-18

Food-grade titanium dioxide (TiO 2 ) is a common and widespread food additive in many processed foods, personal care products, and other industrial categories as it boosts the brightness and whiteness of colours. Although it is generally recognised as safe for humans, there is a growing interest in the health risks associated with its oral intake. This study quantified and identified TiO 2 nanoparticles present in confectionery foods, which are children's favourite foods, with inductively coupled plasma optical emission spectrometry (ICP-OES) and transmission electron microscopy (TEM). A reliable digestion method using hot sulphuric acid and a digestion catalyst (K 2 SO 4 :CuSO 4  = 9:1) was suggested for titanium analysis. Validations of the experimental method were quite acceptable in terms of linearity, recoveries, detection limits, and quantification limits. Of all the 88 analysed foods, TiO 2 was detected in 19 products, all except three declared TiO 2 in their labelling. The mean TiO 2 content of candies, chewing gums, and chocolates were 0.36 mg g -1 , 0.04 mg g -1 , and 0.81 mg g -1 , respectively. Whitish particles isolated from the confectionery foods were confirmed as TiO 2 nanoparticles via TEM and energy dispersive X-ray spectroscopy (EDX), in which nanosized particles (<100 nm) were identified.

Interface engineering of CsPbBr3/TiO2 heterostructure with enhanced optoelectronic properties for all-inorganic perovskite solar cells

NASA Astrophysics Data System (ADS)

Qian, Chong-Xin; Deng, Zun-Yi; Yang, Kang; Feng, Jiangshan; Wang, Ming-Zi; Yang, Zhou; Liu, Shengzhong Frank; Feng, Hong-Jian

2018-02-01

Interface engineering has become a vital method in accelerating the development of perovskite solar cells in the past few years. To investigate the effect of different contacted surfaces of a light absorber with an electron transporting layer, TiO2, we synthesize CsPbBr3/TiO2 thin films with two different interfaces (CsBr/TiO2 and PbBr2/TiO2). Both interfacial heterostructures exhibit enhanced visible light absorption, and the CsBr/TiO2 thin film presents higher absorption than the PbBr2/TiO2 interface, which is attributed to the formation of interface states and the decreased interface bandgap. Furthermore, compared with the PbBr2/TiO2 interface, CsBr/TiO2 solar devices present larger output short circuit current and shorter photoluminescence decay time, which indicates that the CsBr contacting layer with TiO2 can better extract and separate the photo-induced carriers. The first-principles calculations confirm that, due to the existence of staggered gap (type II) offset junction and the interface states, the CsBr/TiO2 interface can more effectively separate the photo-induced carriers and thus drive the electron transfer from the CsPbBr3 perovskite layer to the TiO2 layer. These results may be beneficial to exploit the potential application of all-inorganic perovskite CsPbBr3-based solar cells through the interface engineering route.

Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

PubMed

Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

2012-04-01

TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure.

Nano-titanium dioxide induced cardiac injury in rat under oxidative stress.

PubMed

Sha, BaoYong; Gao, Wei; Wang, ShuQi; Li, Wei; Liang, Xuan; Xu, Feng; Lu, Tian Jian

2013-08-01

Heart diseases, which are related to oxidative stress (OS), negatively affect millions of people from kids to the elderly. Titanium dioxide (TiO2) has widespread applications in our daily life, especially nanoscale TiO2. Compared to the high risk of particulate matter (≤2.5μm) in air to heart disease patients, related research of TiO2 on diseased body is still unknown, which suggest us to explore the potential effects of nanoscale and microscale TiO2 to heart under OS conditions. Here, we used alloxan to induce OS conditions in rat, and investigated the response of heart tissue to TiO2 in healthy and alloxan treated rats. Compared with NMs treatment only, the synergistic interaction between OS conditions and nano-TiO2 significantly reduced the heart-related function indexes, inducing pathological changes of myocardium with significantly increased levels of cardiac troponin I and creatine kinase-MB. In contrast with the void response of micro-TiO2 to heart functions in alloxan treated rats, aggravation of OS conditions might play an important role in cardiac injury after alloxan and nano-TiO2 dual exposure. Our results demonstrated that OS conditions enhanced the adverse effects of nano-TiO2 to heart, suggesting that the use of NMs in stressed conditions (e.g., drug delivery) needs to be carefully monitored. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced interfacial contact between PbS and TiO2 layers in quantum dot solar cells using 2D-arrayed TiO2 hemisphere nanostructures

NASA Astrophysics Data System (ADS)

Lee, Wonseok; Ryu, Ilhwan; Lee, Haein; Yim, Sanggyu

2018-02-01

Two-dimensionally (2D) arrayed hemispherical nanostructures of TiO2 thin films were successfully fabricated using a simple procedure of spin-coating or dip-coating TiO2 nanoparticles onto 2D close-packed polystyrene (PS) nanospheres, followed by PS extraction. The nanostructured TiO2 film was then used as an n-type layer in a lead sulfide (PbS) colloidal quantum dot solar cell. The TiO2 nanostructure could provide significantly increased contacts with subsequently deposited PbS quantum dot layer. In addition, the periodically arrayed nanostructure could enhance optical absorption of the cell by redirecting the path of the incident light and increasing the path length passing though the active layer. As a result, the power conversion efficiency (PCE) reached 5.13%, which is approximately a 1.7-fold increase over that of the control cell without nanostructuring, 3.02%. This PCE enhancement can mainly be attributed to the increase of the short-circuit current density from 19.6 mA/cm2 to 30.6 mA/cm2, whereas the open-circuit voltage and fill factor values did not vary significantly.

Solution-Processed Ultrathin TiO2 Compact Layer Hybridized with Mesoporous TiO2 for High-Performance Perovskite Solar Cells.

PubMed

Jeong, Inyoung; Park, Yun Hee; Bae, Seunghwan; Park, Minwoo; Jeong, Hansol; Lee, Phillip; Ko, Min Jae

2017-10-25

The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO 2 ETLs fabricated by depositing compact TiO 2 (c-TiO 2 ) and mesoporous TiO 2 (mp-TiO 2 ) in sequence exhibit resistive losses due to the contact resistance at the c-TiO 2 /mp-TiO 2 interface and the series resistance arising from the intrinsically low conductivity of TiO 2 . Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO 2 layer hybridized with mp-TiO 2 , which is fabricated by performing one-step spin-coating of a mp-TiO 2 solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of ∼3 nm and ensures that the mp-TiO 2 layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.

TiO2, SiO2 and ZrO2 Nanoparticles Synergistically Provoke Cellular Oxidative Damage in Freshwater Microalgae

PubMed Central

Liu, Yinghan; Ye, Nan; Fang, Hao; Wang, Degao

2018-01-01

Metal-based nanoparticles (NPs) are the most widely used engineered nanomaterials. The individual toxicities of metal-based NPs have been plentifully studied. However, the mixture toxicity of multiple NP systems (n ≥ 3) remains much less understood. Herein, the toxicity of titanium dioxide (TiO2) nanoparticles (NPs), silicon dioxide (SiO2) NPs and zirconium dioxide (ZrO2) NPs to unicellular freshwater algae Scenedesmus obliquus was investigated individually and in binary and ternary combination. Results show that the ternary combination systems of TiO2, SiO2 and ZrO2 NPs at a mixture concentration of 1 mg/L significantly enhanced mitochondrial membrane potential and intracellular reactive oxygen species level in the algae. Moreover, the ternary NP systems remarkably increased the activity of the antioxidant defense enzymes superoxide dismutase and catalase, together with an increase in lipid peroxidation products and small molecule metabolites. Furthermore, the observation of superficial structures of S. obliquus revealed obvious oxidative damage induced by the ternary mixtures. Taken together, the ternary NP systems exerted more severe oxidative stress in the algae than the individual and the binary NP systems. Thus, our findings highlight the importance of the assessment of the synergistic toxicity of multi-nanomaterial systems. PMID:29419775

Synthesis of TiO2/functionalized graphene sheets (FGSs) nanocomposites in super critical CO2

NASA Astrophysics Data System (ADS)

Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chen, Bo; Charpentier, Paul A.

2010-06-01

Highly ordered TiO2 nanowire arrays were prepared on the surface of Functionalized Graphene sheets (FGSs) by solgel method using titanium isopropoxide monomer with acetic acid as the polycondensation agent in the green solvent, supercritical carbon dioxide (sc-CO2). Morphology of synthesized materials was studied by SEM and TEM. Optical properties of the nanocomposites studied by UV spectroscopy which showed high absorption in visible area as well as reduction in their band gap compared to TiO2. By high resolution XPS, chelating bidentate structure of TiO2 with carboxylic group on the surface of graphene sheets can be confirmed. Improvement in the optical properties of the synthesized composites compared to TiO2 alone was confirmed by photocurrent measurements.

Visible-Light-Induced Bactericidal Activity of a Nitrogen-Doped Titanium Photocatalyst against Human Pathogens

PubMed Central

Wong, Ming-Show; Chu, Wen-Chen; Sun, Der-Shan; Huang, Hsuan-Shun; Chen, Jiann-Hwa; Tsai, Pei-Jane; Lin, Nien-Tsung; Yu, Mei-Shiuan; Hsu, Shang-Feng; Wang, Shih-Lien; Chang, Hsin-Hou

2006-01-01

The antibacterial activity of photocatalytic titanium dioxide (TiO2) substrates is induced primarily by UV light irradiation. Recently, nitrogen- and carbon-doped TiO2 substrates were shown to exhibit photocatalytic activities under visible-light illumination. Their antibacterial activity, however, remains to be quantified. In this study, we demonstrated that nitrogen-doped TiO2 substrates have superior visible-light-induced bactericidal activity against Escherichia coli compared to pure TiO2 and carbon-doped TiO2 substrates. We also found that protein- and light-absorbing contaminants partially reduce the bactericidal activity of nitrogen-doped TiO2 substrates due to their light-shielding effects. In the pathogen-killing experiment, a significantly higher proportion of all tested pathogens, including Shigella flexneri, Listeria monocytogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Streptococcus pyogenes, and Acinetobacter baumannii, were killed by visible-light-illuminated nitrogen-doped TiO2 substrates than by pure TiO2 substrates. These findings suggest that nitrogen-doped TiO2 has potential application in the development of alternative disinfectants for environmental and medical usages. PMID:16957236

Efficient Yttrium(III) Chloride-Treated TiO2 Electron Transfer Layers for Performance-Improved and Hysteresis-Less Perovskite Solar Cells.

PubMed

Li, Minghua; Huan, Yahuan; Yan, Xiaoqin; Kang, Zhuo; Guo, Yan; Li, Yong; Liao, Xinqin; Zhang, Ruxiao; Zhang, Yue

2018-01-10

Hybrid organic-inorganic metal halide perovskite solar cells have attracted widespread attention, owing to their high performance, and have undergone rapid development. In perovskite solar cells, the charge transfer layer plays an important role for separating and transferring photogenerated carriers. In this work, an efficient YCl 3 -treated TiO 2 electron transfer layer (ETL) is used to fabricate perovskite solar cells with enhanced photovoltaic performance and less hysteresis. The YCl 3 -treated TiO 2 layers bring about an upward shift of the conduction band minimum (E CBM ), which results in a better energy level alignment for photogenerated electron transfer and extraction from the perovskite into the TiO 2 layer. After optimization, perovskite solar cells based on the YCl 3 -treated TiO 2 layers achieve a maximum power conversion efficiency of about 19.99 % (19.29 % at forward scan) and a steady-state power output of about 19.6 %. Steady-state and time-resolved photoluminescence measurements and impedance spectroscopy are carried out to investigate the charge transfer and recombination dynamics between the perovskite and the TiO 2 electron transfer layer interface. The improved perovskite/TiO 2 ETL interface with YCl 3 treatment is found to separate and extract photogenerated charge rapidly and suppress recombination effectively, which leads to the improved performance. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photosensitivity enhancement with TiO2 in semitransparent light-sensitive skins of nanocrystal monolayers.

PubMed

Akhavan, Shahab; Yeltik, Aydan; Demir, Hilmi Volkan

2014-06-25

We propose and demonstrate light-sensitive nanocrystal skins that exhibit broadband sensitivity enhancement based on electron transfer to a thin TiO2 film grown by atomic layer deposition. In these photosensors, which operate with no external bias, photogenerated electrons remain trapped inside the nanocrystals. These electrons generally recombine with the photogenerated holes that accumulate at the top interfacing contact, which leads to lower photovoltage buildup. Because favorable conduction band offset aids in transferring photoelectrons from CdTe nanocrystals to the TiO2 layer, which decreases the exciton recombination probability, TiO2 has been utilized as the electron-accepting material in these light-sensitive nanocrystal skins. A controlled interface thickness between the TiO2 layer and the monolayer of CdTe nanocrystals enables a photovoltage buildup enhancement in the proposed nanostructure platform. With TiO2 serving as the electron acceptor, we observed broadband sensitivity improvement across 350-475 nm, with an approximately 22% enhancement. Furthermore, time-resolved fluorescence measurements verified the electron transfer from the CdTe nanocrystals to the TiO2 layer in light-sensitive skins. These results could pave the way for engineering nanocrystal-based light-sensing platforms, such as smart transparent windows, light-sensitive walls, and large-area optical detection systems.

TiO2 nanocomposite for the controlled release of drugs against pathogens causing wound infections

NASA Astrophysics Data System (ADS)

Devanand Venkatasubbu, G.; Nagamuthu, S.; Anusuya, T.; Kumar, J.; Chelliah, Ramachandran; Rani Ramakrishnan, Sudha; Antony, Usha; Khan, Imran; Oh, Deog-Hwan

2018-02-01

Chitosan titanium dioxide nanocomposite has been used for wound healing. Titanium dioxide (TiO2) nanoparticles are synthesised and made in to nanocomposite along with chitosan. Curcumin nanoparticles are synthesised. Three different drugs with antimicrobial activity are incorporated into the chitosan/TiO2nanocomposite. Ciprofloxacin, amoxicillin and curcumin nanoparticles are incorporated within the chitosan/TiO2 nanoparticles. The nanoparticles and nanocomposite are characterized with XRD, FTIR, TEM and SEM. Drug loading was found to be around 45% for all the three drug molecules. The drug release profile shows a controlled release of drug molecules from the nanocomposite. Antibacterial studies shows a good inhibition of bacterial species by the nanocomposites.

Molecular dynamics simulations of the adsorption of bone morphogenetic protein-2 on surfaces with medical relevance.

PubMed

Utesch, Tillmann; Daminelli, Grazia; Mroginski, Maria Andrea

2011-11-01

Bone morphogenetic protein-2 (BMP-2) plays a crucial role in osteoblast differentiation and proliferation. Its effective therapeutic use for ectopic bone and cartilage regeneration depends, among other factors, on the interaction with the carrier at the implant site. In this study, we used classical molecular dynamics (MD) and a hybrid approach of steered molecular dynamics (SMD) combined with MD simulations to investigate the initial stages of the adsorption of BMP-2 when approaching two implant surfaces, hydrophobic graphite and hydrophilic titanium dioxide rutile. Surface adsorption was evaluated for six different orientations of the protein, two end-on and four side-on, in explicit water environment. On graphite, we observed a weak but stable adsorption. Depending on the initial orientation, hydrophobic patches as well as flexible loops of the protein were involved in the interaction with graphite. On the contrary, BMP-2 adsorbed only loosely to hydrophilic titanium dioxide. Despite a favorable interaction energy between protein and the TiO(2) surface, the rapid formation of a two-layer water structure prevented the direct interaction between protein and titanium dioxide. The first water adlayer had a strong repulsive effect on the protein, while the second attracted the protein toward the surface. For both surfaces, hydrophobic graphite and hydrophilic titanium dioxide, denaturation of BMP-2 induced by adsorption was not observed on the nanosecond time scale.

Amorphous TiO 2 Compact Layers via ALD for Planar Halide Perovskite Photovoltaics

DOE PAGES

Kim, In Soo; Haasch, Richard T.; Cao, Duyen H.; ...

2016-09-06

A low temperature (< 120 °C) route to pinhole-free amorphous TiO 2 compact layers may pave the way to more efficient, flexible, and stable inverted perovskite halide device designs. Toward this end, we utilize low-temperature thermal atomic layer deposition (ALD) to synthesize ultra-thin (12 nm) compact TiO 2 underlayers for planar halide perovskite PV. While device performance with as-deposited TiO 2 films is poor, we identify room temperature UV-O 3 treatment as a route to device efficiency comparable to crystalline TiO 2 thin films synthesized by higher temperature methods. Here, we further explore the chemical, physical, and interfacial properties 2more » that might explain the improved performance through x-ray diffraction, spectroscopic ellipsometry, Raman spectroscopy, and x-ray photoelectron spectroscopy. These findings challenge our intuition about effective electron selective layers as well as point the way to a greater selection of flexible substrates and more stable inverted device designs.« less

Electrochemical corrosion, wear and cell behavior of ZrO2/TiO2 alloyed layer on Ti-6Al-4V.

PubMed

Li, Jianfang; He, Xiaojing; Zhang, Guannan; Hang, Ruiqiang; Huang, Xiaobo; Tang, Bin; Zhang, Xiangyu

2018-06-01

Ti-6Al-4V (TC4) has received increasing attention as biomaterial but also raised concerns about the long-term safety of releasing of metal ions and poor wear resistance. In this work, an ZrO 2 /TiO 2 alloyed layer was prepared on TC4 by plasma surface alloying with Zr and subsequently annealed in the air for improved corrosion and wear resistant. To assess the corrosion performance of the alloyed layer, the specimens were measured by open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization in simulated body fluid solution. The result shows that the ZrO 2 /TiO 2 alloyed layer exhibits strikingly high polarization resistance, wide passive region and very low current density, indicating the excellent corrosion resistance. The layer also displays significant improvement of wear resistance. Furthermore, the alloyed layer restricts cell adhesion and spreading. We infer that the ZrO 2 /TiO 2 alloyed layer might be potentially useful implanted devices such as biosensors, bioelectronics or drug delivery devices. Copyright © 2018 Elsevier B.V. All rights reserved.

High performance GaN-based LEDs on patterned sapphire substrate with patterned composite SiO2/Al2O3 passivation layers and TiO2/Al2O3 DBR backside reflector.

PubMed

Guo, Hao; Zhang, Xiong; Chen, Hongjun; Zhang, Peiyuan; Liu, Honggang; Chang, Hudong; Zhao, Wei; Liao, Qinghua; Cui, Yiping

2013-09-09

GaN-based light-emitting diodes (LEDs) on patterned sapphire substrate (PSS) with patterned composite SiO(2)/Al(2)O(3) passivation layers and TiO(2)/Al(2)O(3) distributed Bragg reflector (DBR) backside reflector have been proposed and fabricated. Highly passivated Al(2)O(3) layer deposited on indium tin oxide (ITO) layer with excellent uniformity and quality has been achieved with atomic layer deposition (ALD) technology. With a 60 mA current injection, an enhancement of 21.6%, 59.7%, and 63.4% in the light output power (LOP) at 460 nm wavelength was realized for the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers, the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers and Ag mirror + 3-pair TiO(2)/SiO(2) DBR backside reflector, and the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layer and Ag mirror + 3-pair ALD-grown TiO(2)/Al(2)O(3) DBR backside reflector as compared with the conventional LED only with a single SiO(2) passivation layer, respectively.

Green synthesis of highly crystalline and visible-light sensitive C-, N- and S- codoped with Ag TiO2 nanocatalyst

EPA Science Inventory

Titanium dioxide (TiO2) has been a focus of attention as chemically stable, relatively nontoxic, inexpensive and highly efficient photocatalyst applicable for a wide array of uses. However, main disadvantage that severely limits its wider use is the large band gap, 3.0 eV and 3.2...

Transport and Retention of TiO2 Rutile Nanoparticles in Saturated Porous Media: Influence of Solution pH, Ionic Strength, and the Presence of Humic Acid

EPA Science Inventory

The influence of solution pH, ionic strength, and varying concentrations of the Suwannee River Humic Acid (SRHA) on the transport of titanium dioxide (TiO2, rutile) nanoparticle aggregates (nTiO2) in saturated porous media was investigated through systematically examining the tra...

Transport and Retention of TiO2 Rutile Nanoparticles in Saturated Porous Media at Low-Ionic-Strength Conditions: Measurements and Mechanisms

EPA Science Inventory

The mechanisms governing the transport and retention kinetics of titanium dioxide (TiO2, rutile) nanoparticle (NP) aggregates were investigated in saturated porous media. Experiments were carried out under a range of well-controlled ionic strength (from DI water up to 1 mM) and...

Multi-Layered TiO2 Films towards Enhancement of Escherichia coli Inactivation

PubMed Central

Yoriya, Sorachon; Chumphu, Angkana; Pookmanee, Pusit; Laithong, Wreerat; Thepa, Sirichai; Songprakorp, Roongrojana

2016-01-01

Crystalline TiO2 has shown its great photocatalytic properties in bacterial inactivation. This work presents a design fabrication of low-cost, layered TiO2 films assembled reactors and a study of their performance for a better understanding to elucidate the photocatalytic effect on inactivation of E. coli in water. The ability to reduce the number of bacteria in water samples for the layered TiO2 composing reactors has been investigated as a function of time, while varying the parameters of light sources, initial concentration of bacteria, and ratios of TiO2 film area and volume of water. Herein, the layered TiO2 films have been fabricated on the glass plates by thermal spray coating prior to screen printing, allowing a good adhesion of the films. Surface topology and crystallographic phase of TiO2 for the screen-printed active layer have been characterized, resulting in the ratio of anatase:rutile being 80:20. Under exposure to sunlight and a given condition employed in this study, the optimized film area:water volume of 1:2.62 has shown a significant ability to reduce the E. coli cells in water samples. The ratio of surface area of photocatalytic active base to volume of water medium is believed to play a predominant role facilitating the cells inactivation. The kinetic rate of inactivation and its behavior are also described in terms of adsorption of reaction species at different contact times. PMID:28773930

Preparation of TiO2/boron-doped diamond/Ta multilayer films and use as electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Shi, Chao; Li, Hongji; Li, Cuiping; Li, Mingji; Qu, Changqing; Yang, Baohe

2015-12-01

We report nanostructured TiO2/boron-doped diamond (BDD)/Ta multilayer films and their electrochemical performances as supercapacitor electrodes. The BDD films were grown on Ta substrates using electron-assisted hot filament chemical vapor deposition. Ti metal layers were deposited on the BDD surfaces by radio frequency magnetron sputtering, and nanostructured TiO2/BDD/Ta thin films were prepared by electrochemical etching and thermal annealing. The successful formation of TiO2 and Ta layered nanostructures was demonstrated using scanning electron and transmission electron microscopies. The electrochemical responses of these electrodes were evaluated by examining their use as electrical double-layer capacitors, using cyclic voltammetry, and galvanostatic charge/discharge and impedance measurements. When the TiO2/BDD/Ta film was used as the working electrode with 0.1 M Na2SO4 as the electrolyte, the capacitor had a specific capacitance of 5.23 mF cm-2 at a scan rate of 5 mV s-1 for a B/C ratio of 0.1% w/w. Furthermore, the TiO2/BDD/Ta film had improved electrochemical stability, with a retention of 89.3% after 500 cycles. This electrochemical behavior is attributed to the quality of the BDD, the surface roughness and electrocatalytic activities of the TiO2 layer and Ta nanoporous structures, and the synergies between them. These results show that TiO2/BDD/Ta films are promising as capacitor electrodes for special applications.

The influence of adding modified zirconium oxide-titanium dioxide nano-particles on mechanical properties of orthodontic adhesive: an in vitro study.

PubMed

Felemban, Nayef H; Ebrahim, Mohamed I

2017-01-13

The purpose of this in-vitro study was to examine the effect of incorporating different concentrations of Zirconium oxide-Titanium dioxide (ZrO2-TiO2) nanoparticles, which can have antibacterial properties, on the mechanical properties of an orthodontic adhesive. ZrO2-TiO2 (Zirconium oxide, HWNANO, Hongwu International Group Ltd, China) -Titanium dioxide, Nanoshell, USA) nanopowder were incorporated into orthodontic adhesive (Transbond XT, 3 M Unitek, Monrovia, USA) with different concentrations (0.5% weight nonofiller and 1% weight nanofiller). The size of nanoparticle was 70-80 nm for ZrO2 and less than 50 nm for TiO2. For measuring the shear bond strength of the three groups of orthodontic adhesives [Transbond (control), Transbond mixed with 0.5% weight ZrO2-TiO2, and Transbond mixed with 1% weight ZrO2-TiO2], 30 freshly extracted human first premolars were used and bonded with stainless steel metal brackets (Dentaurum®, Discovery®, Deutschland), using the 3 orthodontic adhesives and 3 M Unitek; Transbond TM Plus Self-Etching Primer (10 samples in each group). The recorded values of compressive strength and tensile strength (measured separately on 10 samples of orthodontic adhesives (add the 3 D size of sample, light cured for 40 s on both sides) of each orthodontic adhesives), as well as the shear bond strength in Mega Pascal unit (MPa) were collected and exposed to one-way analysis of variance (ANOVA) and Tukey's post-hoc tests. orthodontic adhesive with 1% weight ZrO2-TiO2 showed the highest mean compressive (73.42 ± 1.55 MPa, p: 0.003, F: 12.74), tensile strength (8.65 ± 0.74 MPa, p: 0.001, F: 68.20), and shear bond strength (20.05 ± 0.2 MPa, p: 0.001, F: 0.17). Adding ZrO2-TiO2 nanoparticle to orthodontic adhesive increased compressive strength, tensile strength, and shear bond strength in vitro, but in vivo studies and randomized clinical trials are needed to validate the present findings.

Fabrication of gelatin-TiO2 nanocomposite film and its structural, antibacterial and physical properties.

PubMed

He, Qingyan; Zhang, Yuchen; Cai, Xixi; Wang, Shaoyun

2016-03-01

Biodegradable fish skin gelatin-titanium dioxide (TiO2) nanocomposite films were fabricated and characterized as a function of incorporating amount of TiO2 nanoparticles (gelatin/TiO2 ratio of 30:1, 20:1 and 10:1). A uniform distribution of TiO2 nanoparticles into gelatin matrix was observed using atomic force microscopy (AFM) micrographs. The data of intrinsic fluorescence spectra, Fourier transform infrared spectra (FTIR) and X-ray diffraction confirmed the interaction between protein and nanoparticles through hydrogen bonding. The TiO2-incorporated gelatin nanocomposite films exhibited more effective antibacterial activity for Escherichia coli after irradiating 120 min by UV light (365 nm), which were 54.38% for E. coli and 44.89% for Staphylococcus aureus, respectively. The analysis of physical properties revealed that addition of TiO2 nanoparticles to gelatin films significantly increased the tensile strength and elongation at break, while decreased its water vapor permeability. The light barrier measurements indicated that these films were highly transparent, and they had excellent barrier properties against UVC light at the same time. The results demonstrated the feasibility of incorporating nanoparticles to improve the properties of gelatin films, and it is of significance in utilizing the gelatin and titanium dioxide to produce biodegradable nanocomposite film as packaging material in food industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Cellulose Acetate Modified Titanium Dioxide (TiO2) Nanoparticles Electrospun Composite Membranes: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Das, Chandan; Gebru, Kibrom Alebel

2017-12-01

Hybrid membranes from Cellulose Acetate (CA) and titanium oxide (TiO2) nanoparticles were fabricated using electrospinning technique. The electrospun hybrid membranes were characterized using field emission scanning electron microscopy, high energy electrons of the energy dispersive X-ray spectroscopy, X-ray diffraction patterns, atomic force microscopy, zeta potential (ζ), and thermo gravimetric analysis. The impact of TiO2 contents on the electrospun membranes matrix was studied in detail. All these characterization results indicated that TiO2 were uniformly distributed within the CA electrospun membrane's matrix. The addition of TiO2 caused formation of largely interconnected fiber networks which in turn have a positive effect on the enhancement of the membrane pore structures. As the amount of TiO2 addition was raised from 0 to 6.5 wt%, the entanglements of the fibers and the spider-net like network among fibers were increased.

Binding of human serum proteins to titanium dioxide particles in vitro.

PubMed

Zaqout, Mazen S K; Sumizawa, Tomoyuki; Igisu, Hideki; Higashi, Toshiaki; Myojo, Toshihiko

2011-01-01

To determine the capacity of human serum proteins to bind to titanium dioxide (TiO(2)) particles of different polymorphs and sizes. TiO(2) particles were mixed with diluted human serum, purified human serum albumin (HSA) or purified human serum gamma-globulin (HGG) solutions. After incubation at 37°C for 1 h, the particles were sedimented by centrifugation, and proteins in the supernatant, as well as those bound to the particles, were analyzed. The total protein concentration in the supernatant was lowered by TiO(2), whereas the albumin/globulin ratio was elevated by the particles. Incubation with TiO(2) also lowered the immunoglobulin, pre-albumin, beta2-microglobulin, ceruloplasmin and retinol-binding protein levels, but not ferritin levels, in the supernatant. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), proteins in the supernatant, especially HGG, were observed to decrease, while those released from the particles (after adding 1% SDS and heating) increased, depending on the dose of TiO(2). Purified HGG and HSA were also bound to TiO(2), although the former appeared to have a higher affinity. All the proteins tested showed the highest binding potency to the amorphous particles (<50 nm) and the lowest to the rutile particles (<5,000 nm), while binding to anatase particles was intermediate. The affinity to the larger anatase was higher than that to smaller anatase particles in most cases. Human serum proteins, including the two major components, HSA and HGG, are bound by TiO(2) particles. The polymorph of the particles seems to be important for determining the binding capacity of the particles and it may affect distribution of the particles in the body.

Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

NASA Astrophysics Data System (ADS)

Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

2018-03-01

Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions

EPA Science Inventory

Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...

High temperature volatility and oxidation measurements of titanium and silicon containing ceramic materials

NASA Astrophysics Data System (ADS)

Nguyen, Quynhgiao N.

Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluates several hot-pressed Ti-containing compositions at high temperatures as a function of oxidation resistance. This study will also evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400°C--1200°C in water containing environments to determine the volatile hydoxyl species using the transpiration method. The water content ranged from 0-76 mole % and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation at all three temperatures: TiO 2 (s) + H2O (g) = TiO(OH)2 (g).

Heterogeneous Reactivity of NO2 with Photocatalytic Paints: A Possible Source of Nitrous Acid (HONO) in the Indoor Environment

NASA Astrophysics Data System (ADS)

Gligorovski, S.; Bartolomei, V.; Gandolfo, A.; Gomez Alvarez, E.; Kleffmann, J.; Wortham, H.

2014-12-01

There is an increasing concern about the indoor air environment, where we spend most of our time. Common methods of improving indoor air quality include controlling pollution sources, increasing ventilation rates or using air purifiers. Photocatalytic remediation technology was suggested as a new possibility to eliminate indoor air pollutants instead of just diluting or disposing them. In the present study, heterogeneous reactions of NO2 were studied on photocatalytic paints containing different size and quantity of TiO2. The heterogeneous reactions were conducted in a photo reactor under simulated atmospheric conditions. The flat pyrex rectangular plates covered with the paint were inserted into the reactor. These plates have been sprayed with the photocatalytic paints at our industrial partner's (ALLIOS) facilities using a high precision procedure that allowed the application of a thin layer of a given thickness of the paint. This allows a homogeneous coverage of the surface with the paint and an accurate determination of the exact amount of paint exposed to gaseous NO2. We demonstrate that the indoor photocatalytic paints which contain TiO2 can substantially reduce the concentrations of nitrogen dioxide (NO2). We show that the efficiency of nitrogen dioxide (NO2) removal increase with the quantity of TiO2 in the range 0 - 7 %. The geometric uptake coefficients increase from 5 · 10-6 to 1.6 · 10-5 under light irradiation of the paints. On the other hand, during the reactions of NO2 with this paint (7 % of TiO2) nitric oxide (NO) and nitrous acid (HONO) are formed. Nitrous acid (HONO) is an important harmful indoor pollutant and its photolysis leads to the formation of highly reactive OH radicals (Gomez Alvarez et al., 2013). Maximum conversion efficiencies of NO2to HONO and NO of 15 % and 33 % were observed at 30 % RH, respectively. Thus, the quantity of TiO2 embedded in the paint is an important parameter regarding the nitrogen oxides (NOx = NO + NO2) remediation, but may also influence formation of harmful by-products such as HONO, which should be considered for future optimization of photocatalytic paints aimed for indoor applications. Reference: Gómez Alvarez E., Amedro D., Afif C., Gligorovski S., Schoemacker C., Fittschen C., Doussin J.F., Wortham H. Proc. Natl. Acad. Sci. U.S.A, 110(33), 13294-13299, 2013.

Biosensing applications of titanium dioxide coated graphene modified disposable electrodes.

PubMed

Kuralay, Filiz; Tunç, Selma; Bozduman, Ferhat; Oksuz, Lutfi; Oksuz, Aysegul Uygun

2016-11-01

In the present work, preparation of titanium dioxide coated graphene (TiO2/graphene) and the use of this nanocomposite modified electrode for electrochemical biosensing applications were detailed. The nanocomposite was prepared with radio frequency (rf) rotating plasma method which serves homogeneous distribution of TiO2 onto graphene. TiO2/graphene was characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Then, this nanocomposite was dissolved in phosphate buffer solution (pH 7.4) and modified onto disposable pencil graphite electrode (PGE) by dip coating for the investigation of the biosensing properties of the prepared electrode. TiO2/graphene modified PGE was characterized with SEM, EDS and cyclic voltammetry (CV). The sensor properties of the obtained surface were examined for DNA and DNA-drug interaction. The detection limit was calculated as 1.25mgL(-1) (n=3) for double-stranded DNA (dsDNA). RSD% was calculated as 2.4% for three successive determinations at 5mgL(-1) dsDNA concentration. Enhanced results were obtained compared to the ones obtained with graphene and unmodified (bare) electrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

The transfer of titanium dioxide nanoparticles from the host plant to butterfly larvae through a food chain

PubMed Central

Kubo-Irie, Miyoko; Yokoyama, Masaaki; Shinkai, Yusuke; Niki, Rikio; Takeda, Ken; Irie, Masaru

2016-01-01

This study aimed to examine the transfer of nanoparticles within a terrestrial food chain. Oviposited eggs of the swallowtail butterfly (Atrophaneura alcinous) were hatched on the leaves of the host plant (Aristolochia debilis), and the root stock and root hairs were submerged in a suspension of 10 μg/ml titanium dioxide nanoparticles (TiO2-NPs) in a 100 ml bottle. The presence of TiO2-NPs in the veins of the leaves was confirmed by X-ray analytical microscopy (X-ray AM). The hatched 1st instar larvae fed on the leaves to moult into 2nd instar larvae. Small agglomerates of TiO2-NPs less than 150 nm in diameter were identified in the vascular tissue of the exposed plant, the midgut and the excreta of the larvae by transmission electron microscopy. The image of Ti elemental mapping by X-ray AM was analysed with the quantitative spatial information mapping (QSIM) technique. The results demonstrated that TiO2-NPs were transferred from the plant to the larvae and they were disseminated throughout the environment via larval excreta. PMID:27030539

Preparation and photocatalytic activity of nonmetal Co-doped titanium dioxide photocatalyst

NASA Astrophysics Data System (ADS)

Sun, Xiaogang; Xing, Jun; Qiu, Jingping

2016-06-01

A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV-Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants.

Enhanced photocatalytic activity towards degradation and H2 evolution over one dimensional TiO2@MWCNTs heterojunction

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Cao, Shuang; Wu, Zhijiao; Zhao, Suling; Piao, Lingyu

2017-04-01

With the distinct electronic and optical properties, multiwall carbon nanotubes (MWCNTs) are identified as an outstanding catalyst support, which can effectively improve the performance of the TiO2 photocatalysts. Herein, the unique one dimensional TiO2@MWCNTs nanocomposites have been prepared by a facile hydrothermal method. The TiO2 coating layers are extremely uniform and the thickness is adjustable for different nanocomposites. XPS measurements confirm that intimate electronic interactions are existed between MWCNTs and TiO2 via interfacial Tisbnd Osbnd C bond and the photoluminescence intensity of the TiO2@MWCNTs nanocomposites are effectively quenched compared with pure TiO2, suggesting the fast electron transfer rates. The thickness of TiO2 coating layers of the TiO2@MWCNTs nanocomposites plays a significant role in the photocatalytic degradation of organic pollutants, such as methylene blue (MB) and Rhodamine B (RhB), and photocatalytic H2 evolution from water. Due to the formation of one dimensional heterojunction of TiO2@MWCNTs nanocomposites and the positive synergistic effect between TiO2 and carbon nanotubes, it is found that the photocatalytic activity of the system is significantly improved.

Mesoporous inverse opal TiO2 film as light scattering layer for dye-sensitized solar cell.

PubMed

Jin, Mingshi; Kim, Sung Soo; Yoon, Minyoung; Li, Zhenghua; Lee, Yoon Yun; Kim, Ji Man

2012-01-01

The light harvesting efficiency of dye-sensitized solar cells was enhanced by using a scattering layer. Such as sphere type TiO2, inverse photonic crystal TiO2, hollow spherical TiO2. Among these materials, the TiO2 with inverse photonic crystal (IPC) structure, synthesized by self-assembly using spherical templates, has attracted much attention due to their photonic crystal characteristics and light scattering effects. However, when applied in the DSSCs, the surface area of IPC is very low that caused insufficient adsorption amount of dye molecules. In the present work, a scattering layer with mesoporous inverse photonic crystal (MIPC) TiO2 film was fabricated by the sol-gel reactions with surfactant-assisted sol-gel method using poly(methyl methacrylate) as the template and titanium (IV) isopropoxide as the TiO2 precursor. After removing the PMMA and surfactant, a highly ordered macroporous structure with mesopores were successfully obtained. The surface area and total pore volume of the MIPC were 82 m2/g and 0.31 cm3/g, respectively, which is much larger than those of the IPC. The DSSCs with the scattering layer of MIPC film exhibited 18 and 10% higher photo-conversion efficiency than those of cells only with a nano-crystalline TiO2 film and with scattering layer of IPC film. From UV-visible spectra of dye solutions, the MIPC film showed a higher amount of absorbed dye molecules than those of the reference and IPC films. Accordingly, an increase in the photo-current density through abundant adsorption of the dye, coupled with inherent light scattering ability can improve overall photo-conversion efficiency.

Effect of TiO2 on the Gas Sensing Features of TiO2/PANi Nanocomposites

PubMed Central

Huyen, Duong Ngoc; Tung, Nguyen Trong; Thien, Nguyen Duc; Thanh, Le Hai

2011-01-01

A nanocomposite of titanium dioxide (TiO2) and polyaniline (PANi) was synthesized by in-situ chemical polymerization using aniline (ANi) monomer and TiCl4 as precursors. SEM pictures show that the nanocomposite was created in the form of long PANi chains decorated with TiO2 nanoparticles. FTIR, Raman and UV-Vis spectra reveal that the PANi component undergoes an electronic structure modification as a result of the TiO2 and PANi interaction. The electrical resistor of the nanocomposite is highly sensitive to oxygen and NH3 gas, accounting for the physical adsorption of these gases. A nanocomposite with around 55% TiO2 shows an oxygen sensitivity of 600–700%, 20–25 times higher than that of neat PANi. The n-p contacts between TiO2 nanoparticles and PANi matrix give rise to variety of shallow donors and acceptor levels in the PANi band gap which enhance the physical adsorption of gas molecules. PMID:22319389

Physical-chemical properties of nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Braga, Natália F.; da Silva, Ana Paula; Moraes Arantes, Tatiane; Lemes, Ana Paula; Cristovan, Fernando Henrique

2018-01-01

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was reinforced with titanium dioxide (TiO2) in concentrations of 1.0%, 2.5% and 5.0% (m/m) to produce nanocomposites by the solvent casting technique. TiO2 was synthesized by a hydrothermal treatment to produce nanoparticles. The nanostructure of the nanoparticles was studied by x-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The XRD confirmed TiO2 crystalline nanoparticles, with a mixture of anatase and rutile phases. Through TEM analysis, the formation of TiO2 nanorod agglomerates with an average diameter and length of 40 and 12 nm, respectively, was observed. The thermal and mechanical properties of the pure PHBV and nanocomposite films were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis. The DSC analysis showed that the glass transition temperature decreased with the inclusion of TiO2 in the PHBV matrix in relation to pure PHBV. The results of biodegradation assays for the PHBV and nanocomposites in an aqueous medium and in soil showed morphological and structural changes for all samples, indicating a high biodegradation rate for this material. The most important conclusion is that the biodegradation of the PHBV was not affected by the addition of nanoparticles, thus enabling the use of nanocomposites in applications requiring biodegradable materials.

No evidence of the genotoxic potential of gold, silver, zinc oxide and titanium dioxide nanoparticles in the SOS chromotest.

PubMed

Nam, Sun-Hwa; Kim, Shin Woong; An, Youn-Joo

2013-10-01

Gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO2 NPs) are widely used in cosmetic products such as preservatives, colorants and sunscreens. This study investigated the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO2 NPs using the SOS chromotest with Escherichia coli PQ37. The maximum exposure concentrations for each nanoparticle were 3.23 mg l(-1) for Au NPs, 32.3 mg l(-1) for Ag NPs and 100 mg l(-1) for ZnO NPs and TiO2 NPs. Additionally, in order to compare the genotoxicity of nanoparticles and corresponding dissolved ions, the ions were assessed in the same way as nanoparticles. The genotoxicity of the titanium ion was not assessed because of the extremely low solubility of TiO2 NPs. Au NPs, Ag NPs, ZnO NPs, TiO2 NPs and ions of Au, Ag and Zn, in a range of tested concentrations, exerted no effects in the SOS chromotest, evidenced by maximum IF (IFmax) values of below 1.5 for all chemicals. Owing to the results, nanosized Au NPs, Ag NPs, ZnO NPs, TiO2 NPs and ions of Au, Ag and Zn are classified as non-genotoxic on the basis of the SOS chromotest used in this study. To the best of our knowledge, this is the first study to evaluate the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO2 NPs using the SOS chromotest. Copyright © 2012 John Wiley & Sons, Ltd.

Histologic and apoptotic changes induced by titanium dioxide nanoparticles in the livers of rats

PubMed Central

Alarifi, Saud; Ali, Daoud; Al-Doaiss, Amin A; Ali, Bahy A; Ahmed, Mukhtar; Al-Khedhairy, Abdulaziz A

2013-01-01

Titanium dioxide (TiO2) nanoparticles are among the top five nanoparticles used in consumer products, paints, and pharmaceutical preparations. Given that exposure to such nanoparticles is mainly via the skin and inhalation, the present study was conducted in male Wistar albino rats (Rattus norvegicus). Our aim was to investigate the effect of TiO2 nanoparticles on hepatic tissue in an attempt to understand their toxicity and the potential effect of their therapeutic and diagnostic use. To investigate the effects of TiO2 nanoparticles on liver tissue, 30 healthy male Wistar albino rats were exposed to TiO2 nanoparticles at doses of 63 mg, 126 mg, and 252 mg per animal for 24 and 48 hours. Serum glutamate oxaloacetate transaminase and alkaline phosphatase activity was altered. Changes in hepatocytes can be summarized as hydropic degeneration, cloudy swelling, fatty degeneration, portal and lobular infiltration by chronic inflammatory cells, and congested dilated central veins. The histologic alterations observed might be an indication of hepatocyte injury due to the toxicity of TiO2 nanoparticles, resulting in an inability to deal with accumulated residues from the metabolic and structural disturbances caused by these nanoparticles. The appearance of cytoplasmic degeneration and destruction of nuclei in hepatocytes suggests that TiO2 nanoparticles interact with proteins and enzymes in hepatic tissue, interfering with antioxidant defense mechanisms and leading to generation of reactive oxygen species which, in turn, may induce stress in hepatocytes, promoting atrophy, apoptosis, and necrosis. More immunohistochemical and ultrastructural investigations are needed in relation to TiO2 nanoparticles and their potential effects when used as therapeutic and diagnostic tools. PMID:24143098

Food-grade TiO2 is trapped by intestinal mucus in vitro but does not impair mucin O-glycosylation and short-chain fatty acid synthesis in vivo: implications for gut barrier protection.

PubMed

Talbot, Pauline; Radziwill-Bienkowska, Joanna M; Kamphuis, Jasper B J; Steenkeste, Karine; Bettini, Sarah; Robert, Véronique; Noordine, Marie-Louise; Mayeur, Camille; Gaultier, Eric; Langella, Philippe; Robbe-Masselot, Catherine; Houdeau, Eric; Thomas, Muriel; Mercier-Bonin, Muriel

2018-06-19

Titanium dioxide (TiO 2 ) particles are commonly used as a food additive (E171 in the EU) for its whitening and opacifying properties. However, the risk of gut barrier disruption is an increasing concern because of the presence of a nano-sized fraction. Food-grade E171 may interact with mucus, a gut barrier protagonist still poorly explored in food nanotoxicology. To test this hypothesis, a comprehensive approach was performed to evaluate in vitro and in vivo interactions between TiO 2 and intestinal mucus, by comparing food-grade E171 with NM-105 (Aeroxyde P25) OECD reference nanomaterial. We tested E171-trapping properties of mucus in vitro using HT29-MTX intestinal epithelial cells. Time-lapse confocal laser scanning microscopy was performed without labeling to avoid modification of the particle surface. Near-UV irradiation of E171 TiO 2 particles at 364 nm resulted in fluorescence emission in the visible range, with a maximum at 510 nm. The penetration of E171 TiO 2 into the mucoid area of HT29-MTX cells was visualized in situ. One hour after exposure, TiO 2 particles accumulated inside "patchy" regions 20 µm above the substratum. The structure of mucus produced by HT29-MTX cells was characterized by MUC5AC immunofluorescence staining. The mucus layer was thin and organized into regular "islands" located approximately 20 µm above the substratum. The region-specific trapping of food-grade TiO 2 particles was attributed to this mucus patchy structure. We compared TiO 2 -mediated effects in vivo in rats after acute or sub-chronic oral daily administration of food-grade E171 and NM-105 at relevant exposure levels for humans. Cecal short-chain fatty acid profiles and gut mucin O-glycosylation patterns remained unchanged, irrespective of treatment. Food-grade TiO 2 is trapped by intestinal mucus in vitro but does not affect mucin O-glycosylation and short-chain fatty acid synthesis in vivo, suggesting the absence of a mucus barrier impairment under "healthy gut" conditions.

Photocatalytic oxidation of organic compounds via waveguide-supported titanium dioxide films

NASA Astrophysics Data System (ADS)

Miller, Lawrence W.

A photochemical reactor based on titanium dioxide (TiO2)-coated silica optical fibers was constructed to explore the use of waveguide-supported TiO2 films for photocatalytic oxidation of organic compounds. The reactor was used for the photocatalytic oxidation of 4-chlorophenol in water. It was confirmed that TiO2 films could be securely attached to silica optical fibers. The 4-chlorophenol (100 mumol/L in water) was successfully oxidized on the TiO2 surface when UV light (310 nm--380 nm) was propagated through the fibers to the films. Rates of 4-chlorophenol oxidation and UV light flux to the fibers were measured. The quantum efficiency of 4-chlorophenol oxidation [defined as the change in 4-chlorophenol concentration divided by the UV light absorbed by the catalyst] was determined as a function of TiO2 catalyst film thickness and internal incident angle of propagating UV light. A maximum quantum efficiency of 2.8% was measured when TiO2 film thickness was ca. 80 nm and the maximum internal incident angle of propagating light was 84°. Quantum efficiency increased with increasing internal angle of incidence of propagating light and decreased with TiO2 film thickness. UV-Visible internal reflection spectroscopy was used to determine whether UV light propagated through TiO2-coated silica waveguides in an ATR mode. Propagation of UV light in an ATR mode was confirmed by the similarities between internal reflection spectra of phenolphthalein obtained with uncoated and TiO2-coated silica crystals. Planar silica waveguides coated with TiO2 were employed in a photocatalytic reactor for the oxidation of formic acid (833 mumol/L in water). It was shown that the quantum yield of formic acid oxidation [defined as the moles of formic acid oxidized divided by the moles of UV photons absorbed by the catalyst] on the waveguide-supported TiO2 surface is enhanced when UV light propagates through the waveguides in an ATR mode. A maximum quantum yield of 3.9% was found for formic acid oxidation on silica waveguides. The waveguides were coated with 150 nm of TiO2 and activated with UV light (lambdamax = 360 nm) propagating through the waveguides at an internal incident angle of 68°.

Co-delivery of ibuprofen and gentamicin from nanoporous anodic titanium dioxide layers.

PubMed

Pawlik, Anna; Jarosz, Magdalena; Syrek, Karolina; Sulka, Grzegorz D

2017-04-01

Although single-drug therapy may prove insufficient in treating bacterial infections or inflammation after orthopaedic surgeries, complex therapy (using both an antibiotic and an anti-inflammatory drug) is thought to address the problem. Among drug delivery systems (DDSs) with prolonged drug release profiles, nanoporous anodic titanium dioxide (ATO) layers on Ti foil are very promising. In the discussed research, ATO samples were synthesized via a three-step anodization process in an ethylene glycol-based electrolyte with fluoride ions. The third step lasted 2, 5 and 10min in order to obtain different thicknesses of nanoporous layers. Annealing the as-prepared amorphous layers at the temperature of 400°C led to obtaining the anatase phase. In this study, water-insoluble ibuprofen and water-soluble gentamicin were used as model drugs. Three different drug loading procedures were applied. The desorption-desorption-diffusion (DDD) model of the drug release was fitted to the experimental data. The effects of crystalline structure, depth of TiO 2 nanopores and loading procedure on the drug release profiles were examined. The duration of the drug release process can be easily altered by changing the drug loading sequence. Water-soluble gentamicin is released for a long period of time if gentamicin is loaded in ATO as the first drug. Additionally, deeper nanopores and anatase phase suppress the initial burst release of drugs. These results confirm that factors such as morphological and crystalline structure of ATO layers, and the procedure of drug loading inside nanopores, allow to alter the drug release performance of nanoporous ATO layers. Copyright © 2017 Elsevier B.V. All rights reserved.

Atomic layer deposition of TiO2 shells on MoO3 nanobelts allowing enhanced lithium storage performance.

PubMed

Xie, Sanmu; Cao, Daxian; She, Yiyi; Wang, Hongkang; Shi, Jian-Wen; Leung, Micheal K H; Niu, Chunming

2018-06-26

Atomic layer deposition (ALD) of TiO2 shells on MoO3 nanobelts (denote as TiO2@MoO3) is realized using a home-made ALD system, which allows a controllable hydrolysis reaction of TiCl4-H2O on an atomic scale. When used as an anode material for lithium ion batteries, the TiO2@MoO3 electrode demonstrates much enhanced lithium storage performance including higher specific capacity, better cycling stability and rate capability.

Visible-Light Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

NASA Technical Reports Server (NTRS)

Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian A.; Richards, Jeffrey T.

2014-01-01

Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure.

Investigation of plasma dynamics during the growth of amorphous titanium dioxide thin films

NASA Astrophysics Data System (ADS)

Kim, Jin-Soo; Jee, Hyeok; Yu, Young-Hun; Seo, Hye-Won

2018-06-01

We have grown amorphous titanium dioxide thin films by reactive DC sputtering method using a different argon/oxygen partial pressure at a room temperature. The plasma dynamics of the process, reactive and sputtered gas particles was investigated via optical emission spectroscopy. We then studied the correlations between the plasma states and the structural/optical properties of the films. The growth rate and morphology of the titanium dioxide thin films turned out to be contingent with the population and the energy profile of Ar, O, and TiO plasma. In particular, the films grown under energetic TiO plasma have shown a direct band-to-band transition with an optical energy band gap up to ∼4.2 eV.

Cake properties in ultrafiltration of TiO2 fine particles combined with HA: in situ measurement of cake thickness by fluid dynamic gauging and CFD calculation of imposed shear stress for cake controlling.

PubMed

Du, Xing; Qu, Fangshu; Liang, Heng; Li, Kai; Chang, Haiqing; Li, Guibai

2016-05-01

In this study, the cake buildup of TiO2 fine particles in the presence of humid acid (HA) and cake layer controlling during ultrafiltration (UF) were investigated. Specifically, we measured the cake thickness using fluid dynamic gauging (FDG) method under various solution conditions, including TiO2 concentration (0.1-0.5 g/L), HA concentration (0-5 mg/L, total organic carbon (TOC)), and pH values (e.g., 4, 6 and 10), and calculated the shear stress distribution induced by stirring using computational fluid dynamics (CFD) to analyze the cake layer controlling conditions, including the operation flux (50-200 L m(-2) h(-1)) and TiO2 concentration (0.1-0.5 g/L). It was found that lower TiO2/HA concentration ratio could lead to exceedingly severe membrane fouling because of the formation of a relatively denser cake layer by filling the voids of cake layer with HA, and pH was essential for cake layer formation owing to the net repulsion between particles. Additionally, it was observed that shear stress was rewarding for mitigating cake growth under lower operation flux as a result of sufficient back-transport forces, and exhibited an excellent performance on cake layer controlling in lower TiO2 concentrations due to slight interaction forces on the vicinity of membrane.

Air Purification Pavement Surface Coating by Atmospheric Pressure Cold Plasma

NASA Astrophysics Data System (ADS)

Westergreen, Joe; Pedrow, Patrick; Shen, Shihui; Jobson, Bertram

2011-10-01

This study develops an atmospheric pressure cold plasma (APCP) reactor to produce activated radicals from precursor molecules, and to immobilize nano titanium dioxide (TiO2) powder to substrate pavement materials. TiO2 has photocatalytic properties and under UV light can be used to oxidize and remove volatile organic compounds (VOCs) and nitrogen oxides (NOx) from the atmosphere. Although TiO2 treated paving materials have great potential to improve air quality, current techniques to adhere TiO2 to substrate materials are either not durable or reduce direct contact of TiO2 with UV light, reducing the photocatalytic effect. To solve this technical difficulty, this study introduces APCP techniques to transportation engineering to coat TiO2 to pavement. Preliminary results are promising and show that TiO2 can be incorporated successfully into an APCP environment and can be immobilized at the surface of the asphalt substrate. The TiO2 coated material with APCP shows the ability to reduce nitrogen oxides when exposed to UV light in an environmental chamber. The plasma reactor utilizes high voltage streamers as the plasma source.

Adsorption properties and photocatalytic activity of TiO2/activated carbon fiber composite

NASA Astrophysics Data System (ADS)

Yao, Shuhua; Song, Shuangping; Shi, Zhongliang

2014-06-01

Photocatalysts of titanium dioxide (TiO2) and TiO2/activated carbon fiber (TiO2/ACF) composite were prepared by sol-gel method, followed by calcining the pure TiO2 sols and the TiO2/ACF sols at 500°C for 2 h in a N2 atmosphere, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms measurement. Batch experiments were conducted to study the adsorption property of TiO2/ACF composite using methylene blue as adsorbate. The adsorption data obtained from different batch experiments were analyzed using pseudo-second-order kinetic model, the experimental data can be adequately described by the pseudo-second-order equation. The photodecomposition behavior of TiO2/ACF was investigated in aqueous solution using methylene blue as target pollutant. It was found that methylene blue could be removed rapidly from water by TiO2/ACF, the photocatalytic decomposition was obviously improved when the photocatalyst was used. Kinetics analysis revealed that the photocatalytic decomposition reaction can be described well by a first-order rate equation.

The influence of material type and composition of TiO2- ZnO on manufacturing of paste for the application of DSSC

NASA Astrophysics Data System (ADS)

Retnaningsih, L.; Muliani, L.; Aggraini, P. N.; Hidayat, J.

2016-11-01

Research, fabrication and material selection for the application of Dye- sensitized solar cell (DSSC) has been performed on glass FTO (Flour Tin Oxide). The material is used in the form of TiO2 paste, TiO2 powder and ZnO powder. Dye-sensitized solar cell (DSSC), is a fotoelektrokimia-based solar cells where the absorption process light done by the dye molecules and the process of separation of inorganic semiconductor materials by charge of Titanium dioxide (TiO2) and Zinc oxide (ZnO). The purpose of this research is to know the exact composition of TiO2 and ZnO materials in order to produce the best efficiency with DSSC. On this research was done making prototype dye-sensitized solar cell using dye Z 907, and semiconductor nanoparticles TiO2 and ZnO powder that is made into a paste by mixing different composition in two variations of samples: A = ZnO (powder) + 40% TiO2 (powder) and B = 60% TiO2 (powder) (40%) + TiO2 (pasta) 60%. The second variation of this high efficiency is value at sample B i.e. TiO2 (powder) + 40% TiO2 (paste) of 60%.

Risk assessment of titanium dioxide nanoparticles via oral exposure, including toxicokinetic considerations.

PubMed

Heringa, Minne B; Geraets, Liesbeth; van Eijkeren, Jan C H; Vandebriel, Rob J; de Jong, Wim H; Oomen, Agnes G

2016-12-01

Titanium dioxide white pigment consists of particles of various sizes, from which a fraction is in the nano range (<100 nm). It is applied in food as additive E 171 as well as in other products, such as food supplements and toothpaste. Here, we assessed whether a human health risk can be expected from oral ingestion of these titanium dioxide nanoparticles (TiO 2 NPs), based on currently available information. Human health risks were assessed using two different approaches: Approach 1, based on intake, i.e. external doses, and Approach 2, based on internal organ concentrations using a kinetic model in order to account for accumulation over time (the preferred approach). Results showed that with Approach 1, a human health risk is not expected for effects in liver and spleen, but a human health risk cannot be excluded for effects on the ovaries. When based on organ concentrations by including the toxicokinetics of TiO 2 NPs (Approach 2), a potential risk for liver, ovaries and testes is found. This difference between the two approaches shows the importance of including toxicokinetic information. The currently estimated risk can be influenced by factors such as absorption, form of TiO 2 , particle fraction, particle size and physico-chemical properties in relation to toxicity, among others. Analysis of actual particle concentrations in human organs, as well as organ concentrations and effects in liver and the reproductive system after chronic exposure to well-characterized TiO 2 (NPs) in animals are recommended to refine this assessment.

Effect of Engineered Nanoparticles on Exopolymeric Substances Release from Marine Phytoplankton

NASA Astrophysics Data System (ADS)

Chiu, Meng-Hsuen; Khan, Zafir A.; Garcia, Santiago G.; Le, Andre D.; Kagiri, Agnes; Ramos, Javier; Tsai, Shih-Ming; Drobenaire, Hunter W.; Santschi, Peter H.; Quigg, Antonietta; Chin, Wei-Chun

2017-12-01

Engineered nanoparticles (ENPs), products from modern nanotechnologies, can potentially impact the marine environment to pose serious threats to marine ecosystems. However, the cellular responses of marine phytoplankton to ENPs are still not well established. Here, we investigate four different diatom species ( Odontella mobiliensis, Skeletonema grethae, Phaeodactylum tricornutum, Thalassiosira pseudonana) and one green algae ( Dunaliella tertiolecta) for their extracellular polymeric substances (EPS) release under model ENP treatments: 25 nm titanium dioxide (TiO2), 10-20 nm silicon dioxide (SiO2), and 15-30 nm cerium dioxide (CeO2). We found SiO2 ENPs can significantly stimulate EPS release from these algae (200-800%), while TiO2 ENP exposure induced the lowest release. Furthermore, the increase of intracellular Ca2+ concentration can be triggered by ENPs, suggesting that the EPS release process is mediated through Ca2+ signal pathways. With better understanding of the cellular mechanism mediated ENP-induced EPS release, potential preventative and safety measures can be developed to mitigate negative impact on the marine ecosystem.

Titanium dioxide@polypyrrole core-shell nanowires for all solid-state flexible supercapacitors.

PubMed

Yu, Minghao; Zeng, Yinxiang; Zhang, Chong; Lu, Xihong; Zeng, Chenghui; Yao, Chenzhong; Yang, Yangyi; Tong, Yexiang

2013-11-21

Herein, we developed a facile two-step process to synthesize TiO2@PPy core-shell nanowires (NWs) on carbon cloth and reported their improved electrochemical performance for flexible supercapacitors (SCs). The fabricated solid-state SC device based on TiO2@PPy core-shell NWs not only has excellent flexibility, but also exhibits remarkable electrochemical performance.

Genotoxic potential of TiO2 on bottlenose dolphin leukocytes.

PubMed

Bernardeschi, Margherita; Guidi, Patrizia; Scarcelli, Vittoria; Frenzilli, Giada; Nigro, Marco

2010-01-01

Titanium dioxide is extensively used in a variety of products, including industrial materials and cosmetics. Studies mainly performed on human cell lines and in vivo exposure on experimental animals have raised concern about the toxic effects of ultrafine titanium dioxide; however, scarce information is available about its impact on aquatic life. The aim of this article was to assess the genotoxic potential of TiO(2) (anatase and rutile) on bottlenose dolphin leukocytes. Blood samples were obtained from four male and one female specimens reared at the Adriatic SeaWorld "Oltremare" (Riccione, Italy). Leukocytes were isolated by the lyses procedure and in vitro exposed to TiO(2) in RPMI. Experimental solutions were sonicated immediately before dosing the cells. Three exposure times (4, 24 and 48 h) and three doses (20, 50 and 100 microg/ml) were tested. Genotoxicity was detected by the single-cell gel electrophoresis (or comet assay) at pH > or = 13, assessing single/double-strand breaks and alkali-labile sites. Cytotoxicity was also detected by the Trypan blue exclusion method. Results showed that both the crystalline forms of TiO(2) were genotoxic for bottlenose dolphin leukocytes, with a statistically significant increase of DNA fragmentation after exposure to 50 and 100 microg/ml for 24 and 48 h. Although preliminary, these are the first data regarding the genetic susceptibility of toothed cetaceans toward an "emerging" pollutant, such as TiO(2) particles.

Investigation of titanium dioxide nanoparticles toxicity and uptake by plants

NASA Astrophysics Data System (ADS)

Larue, C.; Khodja, H.; Herlin-Boime, N.; Brisset, F.; Flank, A. M.; Fayard, B.; Chaillou, S.; Carrière, M.

2011-07-01

Nanoparticles (NP) are introduced in a growing number of commercial products and their production may lead to their release in the environment. Plants may be a potential entry point for NP in the food chain. Up to now, results describing NP phytotoxical effects and plant accumulation are scarce and contradictory. To increase knowledge on titanium dioxide NP (TiO2-NPs) accumulation and impact on plants, we designed a study on three plant species, namely wheat (Triticum aestivum), oilseed rape (Brassica napus) and Arabidopsis thaliana. These plants were exposed in hydroponics to a panel of well-characterized TiO2-NPs, with diameters ranging from 12 to 140 nm, either anatase or rutile. Their accumulation in plant tissues is currently being assessed by complementary imaging techniques: scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro-X-ray fluorescence (SR-μ-XRF) imaging and micro-particle induced X-ray emission (μ-PIXE) imaging. Moreover, the impact of TiO2-NP exposure on germination rate, root elongation, dry biomass and evapotranspiration is evaluated. Preliminary results are presented here, with data collected on wheat plants exposed to 12 nm and 25 nm anatase TiO2-NPs. These results show that TiO2-NPs are taken up by plants, and do not significantly alter their germination and root elongation. These results underline the necessity of deeper evaluation of nanoparticle ecotoxicity, and particularly on their interaction with plants.

The combined toxicological effects of titanium dioxide nanoparticles and bisphenol A on zebrafish embryos

PubMed Central

2014-01-01

Environmental pollutants co-exist and exhibit interaction effects that are different from those associated with a single pollutant. As one of the more commonly manufactured nanomaterials, titanium dioxide nanoparticles (TiO2-NPs) are most likely to bind to other contaminants in water. In this paper, we aimed to study the combined toxicological effects of TiO2-NPs and bisphenol A (BPA) on organism. First, in vitro adsorption experiments were conducted to determine the adsorptive interaction between TiO2-NPs and BPA. Second, zebrafish embryo toxicity tests were performed to monitor for changes in the toxicological effects associated with the two chemicals. The study results demonstrated that adsorptive interactions exist between the two chemicals and increased toxicity effects which included an advanced toxicological effect time, decreased survival, increased morphological abnormalities, and delayed embryo hatching. Also, we suggest that the mode of combined action has a synergistic effect. Based on this, we postulate that concomitant exposure to TiO2-NPs and BPA increased BPA bioavailability and uptake into cells and organisms. Further studies are required to understand the mechanisms of interactions of this mixture. PMID:25177222

A pressure tuned stop-flow atomic layer deposition process for MoS2 on high porous nanostructure and fabrication of TiO2/MoS2 core/shell inverse opal structure

NASA Astrophysics Data System (ADS)

Li, Xianglin; Puttaswamy, Manjunath; Wang, Zhiwei; Kei Tan, Chiew; Grimsdale, Andrew C.; Kherani, Nazir P.; Tok, Alfred Iing Yoong

2017-11-01

MoS2 thin films are obtained by atomic layer deposition (ALD) in the temperature range of 120-150 °C using Mo(CO)6 and dimethyl disulfide (DMDS) as precursors. A pressure tuned stop-flow ALD process facilitates the precursor adsorption and enables the deposition of MoS2 on high porous three dimensional (3D) nanostructures. As a demonstration, a TiO2/MoS2 core/shell inverse opal (TiO2/MoS2-IO) structure has been fabricated through ALD of TiO2 and MoS2 on a self-assembled multilayer polystyrene (PS) structure template. Due to the self-limiting surface reaction mechanism of ALD and the utilization of pressure tuned stop-flow ALD processes, the as fabricated TiO2/MoS2-IO structure has a high uniformity, reflected by FESEM and FIB-SEM characterization. A crystallized TiO2/MoS2-IO structure can be obtained through a post annealing process. As a 3D photonic crystal, the TiO2/MoS2-IO exhibits obvious stopband reflecting peaks, which can be adjusted through changing the opal diameters as well as the thickness of MoS2 layer.

Improved performance of CdSe/CdS/PbS co-sensitized solar cell with double-layered TiO2 films as photoanode

NASA Astrophysics Data System (ADS)

Zhang, Xiaolong; Lin, Yu; Wu, Jihuai; Jing, Jing; Fang, Biaopeng

2017-07-01

Improving the photovoltaic performance of CdSe/CdS/PbS co-sensitized double-layered TiO2 solar cells is reported. Double-layered TiO2 films with TiO2 microspheres as the light blocking layers were prepared. PbS, CdS and CdSe quantum dots (QDs) were assembled onto TiO2 photoanodes by simple successive ionic layer absorption and reaction (SILAR) to fabricate CdSe/CdS/PbS co-sensitized solar cells. An improved power conversion efficiency (PCE) of 5.11% was achieved for CdSe/CdS/PbS co-sensitized solar cells at one sun illumination (AM 1.5 G, 100 mW cm-2), which had an improvement of 22.6% over that of the CdSe/CdS co-sensitized solar cells (4.17%). This enhancement is mainly attributed to their better ability of the absorption of solar light with the existence of PbS QDs, the reduction of charge recombination of the excited electron and longer lifetime of electrons, which have been proved with the photovoltaic studies and electrochemical impedance spectroscopy (EIS).

Improved attachment of mesenchymal stem cells on super-hydrophobic TiO2 nanotubes.

PubMed

Bauer, Sebastian; Park, Jung; von der Mark, Klaus; Schmuki, Patrik

2008-09-01

Self-organized layers of vertically orientated TiO(2) nanotubes providing defined diameters ranging from 15 up to 100nm were grown on titanium by anodic oxidation. These TiO(2) nanotube layers show super-hydrophilic behavior. After coating TiO(2) nanotube layers with a self-assembled monolayer (octadecylphosphonic acid) they showed a diameter-dependent wetting behavior ranging from hydrophobic (108+/-2 degrees ) up to super-hydrophobic (167+/-2 degrees ). Cell adhesion, spreading and growth of mesenchymal stem cells on the unmodified and modified nanotube layers were investigated and compared. We show that cell adhesion and proliferation are strongly affected in the super-hydrophobic range. Adsorption of extracellular matrix proteins as fibronectin, type I collagen and laminin, as well as bovine serum albumin, on the coated and uncoated surfaces showed a strong influence on wetting behavior and dependence on tube diameter.

The Role of Phase Changes in TiO2/Pt/TiO2 Filaments

NASA Astrophysics Data System (ADS)

Bíró, Ferenc; Hajnal, Zoltán; Dücső, Csaba; Bársony, István

2018-04-01

This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance ( R) versus temperature ( T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.

Hydroxyapatite-TiO2-SiO2-Coated 316L Stainless Steel for Biomedical Application

NASA Astrophysics Data System (ADS)

Sidane, Djahida; Khireddine, Hafit; Bir, Fatima; Yala, Sabeha; Montagne, Alex; Chicot, Didier

2017-07-01

This study investigated the effectiveness of titania (TiO2) as a reinforcing phase in the hydroxyapatite (HAP) coating and silica (SiO2) single layer as a bond coat between the TiO2-reinforced hydroxyapatite (TiO2/HAP) top layer and 316L stainless steel (316L SS) substrate on the corrosion resistance and mechanical properties of the underlying 316L SS metallic implant. Single layer of SiO2 film was first deposited on 316L SS substrate and studied separately. Water contact angle measurements, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrophotometer analysis were used to evaluate the hydroxyl group reactivity at the SiO2 outer surface. The microstructural and morphological results showed that the reinforcement of HAP coating with TiO2 and SiO2 reduced the crystallite size and the roughness surface. Indeed, the deposition of 50 vol pct TiO2-reinforced hydroxyapatite layer enhanced the hardness and the elastic modulus of the HAP coating, and the introduction of SiO2 inner layer on the surface of the 316L SS allowed the improvement of the bonding strength and the corrosion resistance as confirmed by scratch studies, nanoindentation, and cyclic voltammetry tests.

Enhanced Charge Collection with Passivation Layers in Perovskite Solar Cells.

PubMed

Lee, Yong Hui; Luo, Jingshan; Son, Min-Kyu; Gao, Peng; Cho, Kyung Taek; Seo, Jiyoun; Zakeeruddin, Shaik M; Grätzel, Michael; Nazeeruddin, Mohammad Khaja

2016-05-01

The Al2 O3 passivation layer is beneficial for mesoporous TiO2 -based perovskite solar cells when it is deposited selectively on the compact TiO2 surface. Such a passivation layer suppressing surface recombination can be formed by thermal decomposition of the perovskite layer during post-annealing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sol-gel preparation of silica and titania thin films

NASA Astrophysics Data System (ADS)

Thoř, Tomáš; Václavík, Jan

2016-11-01

Thin films of silicon dioxide (SiO2) and titanium dioxide (TiO2) for application in precision optics prepared via the solgel route are being investigated in this paper. The sol-gel process presents a low cost approach, which is capable of tailoring thin films of various materials in optical grade quality. Both SiO2 and TiO2 are materials well known for their application in the field of anti-reflective and also highly reflective optical coatings. For precision optics purposes, thickness control and high quality of such coatings are of utmost importance. In this work, thin films were deposited on microscope glass slides substrates using the dip-coating technique from a solution based on alkoxide precursors of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TIP) for SiO2 and TiO2, respectively. As-deposited films were studied using spectroscopic ellipsometry to determine their thickness and refractive index. Using a semi-empirical equation, a relationship between the coating speed and the heat-treated film thickness was described for both SiO2 and TiO2 thin films. This allows us to control the final heat-treated thin film thickness by simply adjusting the coating speed. Furthermore, films' surface was studied using the white-light interferometry. As-prepared films exhibited low surface roughness with the area roughness parameter Sq being on average of 0.799 nm and 0.33 nm for SiO2 and TiO2, respectively.

CO2 Plasma-Treated TiO2 Film as an Effective Electron Transport Layer for High-Performance Planar Perovskite Solar Cells.

PubMed

Wang, Kang; Zhao, Wenjing; Liu, Jia; Niu, Jinzhi; Liu, Yucheng; Ren, Xiaodong; Feng, Jiangshan; Liu, Zhike; Sun, Jie; Wang, Dapeng; Liu, Shengzhong Frank

2017-10-04

Perovskite solar cells (PSCs) have received great attention because of their excellent photovoltaic properties especially for the comparable efficiency to silicon solar cells. The electron transport layer (ETL) is regarded as a crucial medium in transporting electrons and blocking holes for PSCs. In this study, CO 2 plasma generated by plasma-enhanced chemical vapor deposition (PECVD) was introduced to modify the TiO 2 ETL. The results indicated that the CO 2 plasma-treated compact TiO 2 layer exhibited better surface hydrophilicity, higher conductivity, and lower bulk defect state density in comparison with the pristine TiO 2 film. The quality of the stoichiometric TiO 2 structure was improved, and the concentration of oxygen-deficiency-induced defect sites was reduced significantly after CO 2 plasma treatment for 90 s. The PSCs with the TiO 2 film treated by CO 2 plasma for 90 s exhibited simultaneously improved short-circuit current (J SC ) and fill factor. As a result, the PSC-based TiO 2 ETL with CO 2 plasma treatment affords a power conversion efficiency of 15.39%, outperforming that based on pristine TiO 2 (13.54%). These results indicate that the plasma treatment by the PECVD method is an effective approach to modify the ETL for high-performance planar PSCs.

Optimization of Al2O3/TiO2 nanolaminate thin films prepared with different oxide ratios, for use in organic light-emitting diode encapsulation, via plasma-enhanced atomic layer deposition.

PubMed

Kim, Lae Ho; Jeong, Yong Jin; An, Tae Kyu; Park, Seonuk; Jang, Jin Hyuk; Nam, Sooji; Jang, Jaeyoung; Kim, Se Hyun; Park, Chan Eon

2016-01-14

Encapsulation is essential for protecting the air-sensitive components of organic light-emitting diodes (OLEDs), such as the active layers and cathode electrodes. Thin film encapsulation approaches based on an oxide layer are suitable for flexible electronics, including OLEDs, because they provide mechanical flexibility, the layers are thin, and they are easy to prepare. This study examined the effects of the oxide ratio on the water permeation barrier properties of Al2O3/TiO2 nanolaminate films prepared by plasma-enhanced atomic layer deposition. We found that the Al2O3/TiO2 nanolaminate film exhibited optimal properties for a 1 : 1 atomic ratio of Al2O3/TiO2 with the lowest water vapor transmission rate of 9.16 × 10(-5) g m(-2) day(-1) at 60 °C and 90% RH. OLED devices that incorporated Al2O3/TiO2 nanolaminate films prepared with a 1 : 1 atomic ratio showed the longest shelf-life, in excess of 2000 hours under 60 °C and 90% RH conditions, without forming dark spots or displaying edge shrinkage.

Semiconducting and quartz microbalance (QCM) humidity sensor properties of TiO2 by sol gel calcination method

NASA Astrophysics Data System (ADS)

Yakuphanoglu, Fahrettin

2012-06-01

Titanium dioxide (TiO2) material was synthesized using the sol gel calcination method. The structural properties of the TiO2 semiconductor were investigated by atomic force microscopy. The electrical conductivity of the TiO2 was measured as a function of temperature and TiO2 exhibits a conductivity of 2.55 × 10-6 S/m at room temperature with activation energy of 104 meV. The electrical conductivity of the TiO2 at room temperature is higher than that of nanocrystalline TiO2 (3 × 10-7 S/m) and TiO2 thin film in air (5 × 10-9 S/m) and in vacuum (8.8 × 10-10 S/m). It was found that the electrical transport mechanism of the TiO2 is controlled by thermally activated mechanism. The optical band gap of the TiO2 powder sample was determined to be 3.17 eV, which is good in agreement with the bulk TiO2 (Eg = 3.2 eV). Up to our knowledge, there is no any reported data about the band gap of TiO2 nanopowder based on the diffused reflectance calculation. Quartz crystal microbalance (QCM) TiO2 humidity sensor was prepared. The sensor indicates a large frequency change with an interaction occurred between TiO2 and humidity molecules. The sensor exhibits a good repeatability when it was exposed to the moist air of 65% RH.

Differential Growth of and Nanoscale TiO2 Accumulation in Tetrahymena thermophila by Direct Feeding versus Trophic Transfer from Pseudomonas aeruginosa

PubMed Central

Mielke, Randall E.; Priester, John H.; Werlin, Rebecca A.; Gelb, Jeff; Horst, Allison M.; Orias, Eduardo

2013-01-01

Nanoscale titanium dioxide (TiO2) is increasingly used in consumer goods and is entering waste streams, thereby exposing and potentially affecting environmental microbes. Protozoans could either take up TiO2 directly from water and sediments or acquire TiO2 during bactivory (ingestion of bacteria) of TiO2-encrusted bacteria. Here, the route of exposure of the ciliated protozoan Tetrahymena thermophila to TiO2 was varied and the growth of, and uptake and accumulation of TiO2 by, T. thermophila were measured. While TiO2 did not affect T. thermophila swimming or cellular morphology, direct TiO2 exposure in rich growth medium resulted in a lower population yield. When TiO2 exposure was by bactivory of Pseudomonas aeruginosa, the T. thermophila population yield and growth rate were lower than those that occurred during the bactivory of non-TiO2-encrusted bacteria. Regardless of the feeding mode, T. thermophila cells internalized TiO2 into their food vacuoles. Biomagnification of TiO2 was not observed; this was attributed to the observation that TiO2 appeared to be unable to cross the food vacuole membrane and enter the cytoplasm. Nevertheless, our findings imply that TiO2 could be transferred into higher trophic levels within food webs and that the food web could be affected by the decreased growth rate and yield of organisms near the base of the web. PMID:23851096

Effect of TiO2 nanoparticles on some photophysical characteristics of ketocyanine dyes.

PubMed

Thipperudrappa, Javuku; Raghavendra, U P; Basanagouda, Mahantesha

2017-11-01

The effect of titanium dioxide (TiO 2 ) nanoparticles (NPs) on photophysical characteristics of 2,5-di[(E)-1-(4-dimethylaminophenyl) methylidine]-1-cyclopentanone (2,5-DMAPMC) and 2,5-di[(E)-1-(4-diethylaminophenyl)methylidine]-1-cyclopentanone (2,5-DEAPMC) ketocyanine dyes has been studied using absorption, steady-state and time-resolved fluorescence spectroscopy. The magnitudes of association constants determined based on modified absorption spectrum of dyes due to the presence of TiO 2 NPs indicate the interaction of TiO 2 NPs with dye molecules. The quenching of fluorescence intensity of dyes by TiO 2 NPs is observed and it follows linear Stern-Volmer (S-V) equation. The magnitude of quenching rate parameter suggests the involvement of static quenching mechanism. The involvement of electron transfer process in reducing fluorescence intensity of dyes has been discussed. Also, varying influence of TiO 2 NPs on two dyes is explained based on the presence of different alkyl substituent in two dyes. Copyright © 2017 John Wiley & Sons, Ltd.

Critical review of the safety assessment of titanium dioxide additives in food.

PubMed

Winkler, Hans Christian; Notter, Tina; Meyer, Urs; Naegeli, Hanspeter

2018-06-01

Nanomaterial engineering provides an important technological advance that offers substantial benefits for applications not only in the production and processing, but also in the packaging and storage of food. An expanding commercialization of nanomaterials as part of the modern diet will substantially increase their oral intake worldwide. While the risk of particle inhalation received much attention, gaps of knowledge exist regarding possible adverse health effects due to gastrointestinal exposure. This problem is highlighted by pigment-grade titanium dioxide (TiO 2 ), which confers a white color and increased opacity with an optimal particle diameter of 200-300 nm. However, size distribution analyses showed that batches of food-grade TiO 2 always comprise a nano-sized fraction as inevitable byproduct of the manufacturing processes. Submicron-sized TiO 2 particles, in Europe listed as E 171, are widely used as a food additive although the relevant risk assessment has never been satisfactorily completed. For example, it is not possible to derive a safe daily intake of TiO 2 from the available long-term feeding studies in rodents. Also, the use of TiO 2 particles in the food sector leads to highest exposures in children, but only few studies address the vulnerability of this particular age group. Extrapolation of animal studies to humans is also problematic due to knowledge gaps as to local gastrointestinal effects of TiO 2 particles, primarily on the mucosa and the gut-associated lymphoid system. Tissue distributions after oral administration of TiO 2 differ from other exposure routes, thus limiting the relevance of data obtained from inhalation or parenteral injections. Such difficulties and uncertainties emerging in the retrospective assessment of TiO 2 particles exemplify the need for a fit-to-purpose data requirement for the future evaluation of novel nano-sized or submicron-sized particles added deliberately to food.

Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

DOE PAGES

Khromova, Irina; Kužel, Petr; Brener, Igal; ...

2016-06-27

Monocrystalline titanium dioxide (TiO 2) micro-spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii inline imagem through near-field time-domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub-wavelength aperture probe, we found that the magnetic dipole resonances in TiO 2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO 2 micro-resonators can be used to enhance the interplay of magneticmore » and electric dipole resonances in the emerging THz all-dielectric metamaterial technology.« less

Obtaining titanium dioxide nanoparticles with spherical shape and antimicrobial properties using M. citrifolia leaves extract by hydrothermal method.

PubMed

M, Sundrarajan; K, Bama; M, Bhavani; S, Jegatheeswaran; S, Ambika; A, Sangili; P, Nithya; R, Sumathi

2017-06-01

In this work, we synthesized titanium dioxide (TiO 2 ) nanoparticles using leaf extract of Morinda citrifolia (M. citrifolia) by the advanced hydrothermal method. The synthesized TiO 2 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transmission infrared (FT-IR), Ultraviolet-visible diffuse reflectance (UV-Vis DRS), Ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM with EDX) techniques. The XRD major peak at 27.3° corresponds to the (110) lattice plane of tetragonal rutile TiO 2 phase and average crystalline size of nanoparticles is 10nm. The FT-IR result confirmed that TiO 2 nanoparticles and the presences of very few amount of anthraquinone and phenolic compounds of the leaf extract. The obtained nanoparticles were also characterized by UV-Vis DRS absorption spectroscopy and an intense band at 423nm clearly reveals the formation of nanoparticles. SEM images with EDX spectra clearly reveal the size of the nanoparticles, between 15 and 19nm in excellent quasi-spherical shape, by virtue of stabilization (capping) agent. The presence of elements-titanium and oxygen was verified with EDX spectrum. Furthermore, the inhibitory activity of green synthesized TiO 2 nanoparticles was tested against human pathogens like Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger by the agar well-diffusion method. The TiO 2 nanoparticles exhibited superior antimicrobial activity against Gram-positive bacteria, demonstrating their antimicrobial value against pathogenic diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of titanium dioxide nanoparticles on antioxidant gene expression in tilapia ( Oreochromis niloticus)

NASA Astrophysics Data System (ADS)

Varela-Valencia, Ruth; Gómez-Ortiz, Nikte; Oskam, Gerko; de Coss, Romeo; Rubio-Piña, Jorge; del Río-García, Marcela; Albores-Medina, Arnulfo; Zapata-Perez, Omar

2014-04-01

The reactivity of nanoparticles (NPs) in biological systems is well recognized, but there are huge gaps in our understanding of NP toxicity in fish, despite a number of recent ecotoxicity studies. Therefore, the aim of this research was to evaluate the effect of titanium dioxide NPs (TiO2-NPs) on antioxidant gene expression in the tilapia, Oreochromis niloticus. First, different sizes, shapes, and phases of TiO2-NPs were synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Fish were injected intraperitoneally with different concentrations (0.1, 1.0, 10.0 mg/L), sizes (7, 14, and 21 nm), and phases (anatase and rutile) of TiO2-NPs, and sacrificed 3, 6, 12, and 24 h after injection, when their livers were removed. Total RNA was extracted, and expression of the catalase ( CAT), glutathione- S-transferase ( GST), and superoxide dismutase ( SOD) genes was assessed by real-time polymerase chain reaction (RT-PCR). The results showed that injection of 1.0 mg/L TiO2-NPs induced an initial mild increase in CAT, GST, and SOD gene expression in tilapia, after which transcript levels decreased. Fish injected with 7 and 14 nm TiO2-NPs showed an increase in antioxidant transcript levels 6 h after treatment. Finally, the rutile form generated stronger induction of the GST gene than anatase TiO2-NPs during the first 6 h after injection, which suggests that exposure to rutile causes higher levels of reactive oxygen species to be produced.

NMR-based metabonomic study of the sub-acute toxicity of titanium dioxide nanoparticles in rats after oral administration

NASA Astrophysics Data System (ADS)

Bu, Qian; Yan, Guangyan; Deng, Pengchi; Peng, Feng; Lin, Hongjun; Xu, Youzhi; Cao, Zhixing; Zhou, Tian; Xue, Aiqin; Wang, Yanli; Cen, Xiaobo; Zhao, Ying-Lan

2010-03-01

As titanium dioxide nanoparticles (TiO2 NPs) are widely used commercially, their potential toxicity on human health has attracted particular attention. In the present study, the oral toxicological effects of TiO2 NPs (dosed at 0.16, 0.4 and 1 g kg - 1, respectively) were investigated using conventional approaches and metabonomic analysis in Wistar rats. Serum chemistry, hematology and histopathology examinations were performed. The urine and serum were investigated by 1H nuclear magnetic resonance (NMR) using principal components and partial least squares discriminant analysis. The metabolic signature of urinalysis in TiO2 NP-treated rats showed increases in the levels of taurine, citrate, hippurate, histidine, trimethylamine-N-oxide (TMAO), citrulline, α-ketoglutarate, phenylacetylglycine (PAG) and acetate; moreover, decreases in the levels of lactate, betaine, methionine, threonine, pyruvate, 3-D-hydroxybutyrate (3-D-HB), choline and leucine were observed. The metabonomics analysis of serum showed increases in TMAO, choline, creatine, phosphocholine and 3-D-HB as well as decreases in glutamine, pyruvate, glutamate, acetoacetate, glutathione and methionine after TiO2 NP treatment. Aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) were elevated and mitochondrial swelling in heart tissue was observed in TiO2 NP-treated rats. These findings indicate that disturbances in energy and amino acid metabolism and the gut microflora environment may be attributable to the slight injury to the liver and heart caused by TiO2 NPs. Moreover, the NMR-based metabolomic approach is a reliable and sensitive method to study the biochemical effects of nanomaterials.

Quantum Dot Sensitized Solar Cells Based on TiO2/AgInS2

NASA Astrophysics Data System (ADS)

Pawar, Sachin A.; Jeong, Jae Pil; Patil, Dipali S.; More, Vivek M.; Lee, Rochelle S.; Shin, Jae Cheol; Choi, Won Jun

2018-05-01

Quantum dot heterojunctions with type-II band alignment can efficiently separate photogenerated electron-hole pairs and, hence, are useful for solar cell studies. In this study, a quantum dot sensitized solar cell (QDSSC) made of TiO2/AgInS2 is achieved to boost the photoconversion efficiency for the TiO2-based system by varying the AgInS2 layer's thickness. The TiO2 nanorods array film is prepared by using a simple hydrothermal technique. The formation of a AgInS2 QD-sensitized TiO2-nanorod photoelectrode is carried out by successive ionic layer adsorption and reaction (SILAR) technique. The effect of the QD layer on the performance of the solar cell is studied by varying the SILAR cycles of the QD coating. The synthesized electrode materials are characterized by using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and solar cell performances. The results indicate that the nanocrystals have effectively covered the outer surfaces of the TiO2 nanorods. The interfacial structure of quantum dots (QDs)/TiO2 is also investigated, and the growth interface is verified. A careful comparison between TiO2/AgInS2 sensitized cells reveals that the trasfer of electrons and hole proceeds efficiently, the recombination is suppressed for the optimum thickness of the QD layer and light from the entire visible spectrum is utilised. Under AM 1.5G illumination, a high photocurrent of 1.36 mAcm-2 with an improved power conversion efficiency of 0.48% is obtained. The solar cell properties of our photoanodes suggest that the TiO2 nanorod array films co-sensitized by AgInS2 nanoclusters have potential applications in solar cells.

Synthesis of uniform layered protonated titanate hierarchical spheres and their transformation to anatase TiO2 for lithium-ion batteries.

PubMed

Wu, Hao Bin; Lou, Xiong Wen David; Hng, Huey Hoon

2012-02-13

Layered protonated titanates (LPTs), a class of interesting inorganic layered materials, have been widely studied because of their many unique properties and their use as precursors to many important TiO(2)-based functional materials. In this work, we have developed a facile solvothermal method to synthesize hierarchical spheres (HSs) assembled from ultrathin LPT nanosheets. These LPT hierarchical spheres possess a porous structure with a large specific surface area and high stability. Importantly, the size and morphology of the LPT hierarchical spheres are easily tunable by varying the synthesis conditions. These LPT HSs can be easily converted to anatase TiO(2) HSs without significant structural alteration. Depending on the calcination atmosphere of air or N(2), pure anatase TiO(2) HSs or carbon-supported TiO(2) HSs, respectively, can be obtained. Remarkably, both types of TiO(2) HSs manifest excellent cyclability and rate capability when evaluated as anode materials for high-power lithium-ion batteries. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Al2O3 and TiO2 atomic layer deposition on copper for water corrosion resistance.

PubMed

Abdulagatov, A I; Yan, Y; Cooper, J R; Zhang, Y; Gibbs, Z M; Cavanagh, A S; Yang, R G; Lee, Y C; George, S M

2011-12-01

Al(2)O(3) and TiO(2) atomic layer deposition (ALD) were employed to develop an ultrathin barrier film on copper to prevent water corrosion. The strategy was to utilize Al(2)O(3) ALD as a pinhole-free barrier and to protect the Al(2)O(3) ALD using TiO(2) ALD. An initial set of experiments was performed at 177 °C to establish that Al(2)O(3) ALD could nucleate on copper and produce a high-quality Al(2)O(3) film. In situ quartz crystal microbalance (QCM) measurements verified that Al(2)O(3) ALD nucleated and grew efficiently on copper-plated quartz crystals at 177 °C using trimethylaluminum (TMA) and water as the reactants. An electroplating technique also established that the Al(2)O(3) ALD films had a low defect density. A second set of experiments was performed for ALD at 120 °C to study the ability of ALD films to prevent copper corrosion. These experiments revealed that an Al(2)O(3) ALD film alone was insufficient to prevent copper corrosion because of the dissolution of the Al(2)O(3) film in water. Subsequently, TiO(2) ALD was explored on copper at 120 °C using TiCl(4) and water as the reactants. The resulting TiO(2) films also did not prevent the water corrosion of copper. Fortunately, Al(2)O(3) films with a TiO(2) capping layer were much more resilient to dissolution in water and prevented the water corrosion of copper. Optical microscopy images revealed that TiO(2) capping layers as thin as 200 Å on Al(2)O(3) adhesion layers could prevent copper corrosion in water at 90 °C for ~80 days. In contrast, the copper corroded almost immediately in water at 90 °C for Al(2)O(3) and ZnO films by themselves on copper. Ellipsometer measurements revealed that Al(2)O(3) films with a thickness of ~200 Å and ZnO films with a thickness of ~250 Å dissolved in water at 90 °C in ~10 days. In contrast, the ellipsometer measurements confirmed that the TiO(2) capping layers with thicknesses of ~200 Å on the Al(2)O(3) adhesion layers protected the copper for ~80 days in water at 90 °C. The TiO(2) ALD coatings were also hydrophilic and facilitated H(2)O wetting to copper wire mesh substrates. © 2011 American Chemical Society

Electrodeposition of hydroxyapatite nanoparticles onto ultra-fine TiO2 nanotube layer by electrochemical reaction in mixed electrolyte.

PubMed

Park, Su-Jung; Jang, Jae-Myung

2011-08-01

Electrochemical depositions of HAp nanoparticles onto Ultra-fine TiO2 nanotube layer were carried out by the electrochemical reaction in mixed electrolyte of 1.6 M (NH4)H2PO4 + 0.8 M NH4F containing 0.15 and 0.25 wt% HAp. The Ca/P ratios of the HAp nanoparticles were evaluated by EDS analysis and their values were 1.53 and 1.66 respectively. The distribution quantity of Ca and P were remained at the middle region of TiO2 nanotube, but the Ti element was mainly stayed at the bottom of barrier layer from the result of line scanning diagram. Especially, adsorbed phosphate ions facilitated nucleation of nanophase calcium phosphate material inside the TiO2 nanotubu layer that resulted in vertical growth of HAp nanoparticles. These surfaces and structures were all effective for biocompatibility from the SBF tests.

Electrical level of defects in single-layer two-dimensional TiO2

NASA Astrophysics Data System (ADS)

Song, X. F.; Hu, L. F.; Li, D. H.; Chen, L.; Sun, Q. Q.; Zhou, P.; Zhang, D. W.

2015-11-01

The remarkable properties of graphene and transition metal dichalcogenides (TMDCs) have attracted increasing attention on two-dimensional materials, but the gate oxide, one of the key components of two-dimensional electronic devices, has rarely reported. We found the single-layer oxide can be used as the two dimensional gate oxide in 2D electronic structure, such as TiO2. However, the electrical performance is seriously influenced by the defects existing in the single-layer oxide. In this paper, a nondestructive and noncontact solution based on spectroscopic ellipsometry has been used to detect the defect states and energy level of single-layer TiO2 films. By fitting the Lorentz oscillator model, the results indicate the exact position of defect energy levels depends on the estimated band gap and the charge state of the point defects of TiO2.

Mild solution-processed metal-doped TiO2 compact layers for hysteresis-less and performance-enhanced perovskite solar cells

NASA Astrophysics Data System (ADS)

Liang, Chao; Li, Pengwei; Zhang, Yiqiang; Gu, Hao; Cai, Qingbin; Liu, Xiaotao; Wang, Jiefei; Wen, Hua; Shao, Guosheng

2017-12-01

TiO2 is extensively used as electron-transporting material on perovskite solar cells (PSCs). However, traditional TiO2 processing method needs high annealing temperature (>450 °C) and pure TiO2 suffers from low electrical mobility and poor conductivity. In this study, a general one-pot solution-processed method is devised to grow uniform crystallized metal-doped TiO2 thin film as large as 15 × 15 cm2. The doping process can be controlled effectively via a series of doping precursors from niobium (V), tin (IV), tantalum (V) to tungsten (VI) chloride. As far as we know, this is so far the lowest processing temperature for metal-doped TiO2 compact layers, as low as 70 °C. The overall performance of PSCs employing the metal-doped TiO2 layers is significantly improved in term of hysteresis effect, short circuit current, open-circuit voltage, fill factor, power conversion efficiency, and device stability. With the insertion of metal ions into TiO2 lattice, the corresponding CH3NH3PbI3 PSC leads to a ∼25% improved PCE of over 16% under irradiance of 100 mW cm-2 AM1.5G sunlight, compared with control device. The results indicate that this mild solution-processed metal-doped TiO2 is an effective industry-scale way for fabricating hysteresis-less and high-performance PSCs.

Low cost synthesis of TiO2-C nanocomposite powder for high efficiency visible light photocatalysis

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-04-01

Titanium dioxide-carbon nanocomposite powder was synthesized via a low cost chemical route using oleic acid and titanium tetra-isopropoxide. Since the carbon remained mainly on the surface of the TiO2 nanoparticles, the powder had black color. The composition of the powder was analyzed by X-ray photoelectron spectroscopy and the structure was studied with X-ray diffraction and transmission electron microscopy. The visible photocatalytic activity of the black TiO2 powder was investigated by studying the photo-bleaching of methylene blue under visible light. Our experimental observation showed that the black-TiO2 powder had a higher visible photocatalytic activity compared to the commercial TiO2 powder (P25 Degussa).

Fabrication of Organic Transistors Using Nanomaterials for Sensing Applications

NASA Astrophysics Data System (ADS)

Harb, Mohamed E.; Ebrahim, Shaker; Soliman, Moataz; Shabana, Mahmoud

2018-01-01

In this work, an organic field-effect transistor (OFET) was fabricated and characterized based on the bottom contact of a polyaniline (PANI) or PANI/TiO2 nanocomposite as an active layer and SiO2 as an insulating layer to be used for ammonia gas sensing applications. The OFET sensors exhibited a change in the drain current when exposed to NH3. Titanium dioxide (TiO2) nanoparticles with different weight percentages (0-50 wt.%) were added to dope PANI and enhance charge carrier transport, although the response of both the PANI OFET sensor and PANI/TiO2 OFET sensor has reached saturation value at almost the same period. The response of PANI/TiO2 transistor is (2.5), which is much higher than that of PANI (0.17). The results showed that the sensor response of the OFET device fabricated with PANI/TiO2 is 15 times greater than that with an OFET device fabricated using pristine PANI.

Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

PubMed

Dai, Rui; Zhang, Anqi; Pan, Zhichang; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Hu, Linfeng; Zheng, Gengfeng

2016-05-01

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vivo and in vitro toxicological effects of titanium dioxide nanoparticles on small intestine

NASA Astrophysics Data System (ADS)

Tassinari, Roberta; La Rocca, Cinzia; Stecca, Laura; Tait, Sabrina; De Berardis, Barbara; Ammendolia, Maria Grazia; Iosi, Francesca; Di Virgilio, Antonio; Martinelli, Andrea; Maranghi, Francesca

2015-06-01

In European Union, titanium dioxide (TiO2) as bulk material is a food additive (E171) and - as nanoparticle (NP) - is used as a white pigment in several products (e.g. food, cosmetics, drugs). E171 contains approximately 36% of particles less than 100 nm in at least one dimension and TiO2 NP exposure is estimated fairly below 2.5 mg/person/day. The gastrointestinal tract is a route of entry for NPs, thus representing a potential target of effects. In in vivo study, the effects of TiO2 NP in adult rat small intestine have been evaluated by oral administration of 0 (CTRL), 1 and 2 mg/kg body weight per day - relevant to human dietary intake. Detailed quali/quantitative histopathological analyses were performed on CTRL and treated rat samples. Scanning electron microscopy (SEM) analysis was performed on small intestine. An in vitro study on Caco-2 cells was also used in order to evaluate the potential cytotoxic effects directly on enterocytes through the lactate dehydrogenase (LDH) assay. Suspensions of TiO2 NPs for in vitro and in vivo study were characterized by EM. Histomorphometrical data showed treatment-related changes of villus height and widths in male rats. Significantly different from CTRL decreased LDH levels in the medium were detected in vitro at 24h with 2.5, 5, 10 and 20 µg/cm2 levels of TiO2 NPs. SEM analysis showed no damaged areas. Overall the results showed that enterocytes may represent a target of TiO2 NP toxicity by direct exposure both in vivo and in vitro models.

Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation.

PubMed

Sudhagar, P; Asokan, K; Jung, June Hyuk; Lee, Yong-Gun; Park, Suil; Kang, Yong Soo

2011-12-01

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm(-2)) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm(-2)). When SHI irradiation of oxygen ions of fluence 1 × 10(13) ions/cm(2) was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation

PubMed Central

2011-01-01

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs. PMID:27502653

Sol-gel-Derived nano-sized double layer anti-reflection coatings (SiO2/TiO2) for low-cost solar cell fabrication.

PubMed

Lee, Seung Jun; Hur, Man Gyu; Yoon, Dae Ho

2013-11-01

We investigate nano-sized double layer anti-reflection coatings (ARCs) using a TiO2 and SiO2 sol-gel solution process for mono-crystalline silicon solar cells. The process can be easily adapted for spraying sol-gel coatings to reduce manufacturing cost. The spray-coated SiO2/TiO2 nano-sized double layer ARCs were deposited on mono-crystalline silicon solar cells, and they showed good optical properties. The spray coating process is a lower-cost fabrication process for large-scale coating than vacuum deposition processes such as PECVD. The measured average optical reflectance (300-1200 nm) was about approximately 8% for SiO2/TiO2 nano-sized double layer ARCs. The electrical parameters of a mono-crystalline silicon solar cell and reflection losses show that the SiO2/TiO2 stacks can improve cell efficiency by 0.2% compared to a non-coated mono-crystalline silicon solar cell. In the results, good correlation between theoretical and experimental data was obtained. We expect that the sol-gel spray-coated mono-crystalline silicon solar cells have high potential for low-cost solar cell fabrication.

Transparent TiO 2 nanotube array photoelectrodes prepared via two-step anodization

DOE PAGES

Kim, Jin Young; Zhu, Kai; Neale, Nathan R.; ...

2014-04-04

Two-step anodization of transparent TiO 2 nanotube arrays has been demonstrated with aid of a Nb-doped TiO 2 buffer layer deposited between the Ti layer and TCO substrate. Enhanced physical adhesion and electrochemical stability provided by the buffer layer has been found to be important for successful implementation of the two-step anodization process. As a result, with the proposed approach, the morphology and thickness of NT arrays could be controlled very precisely, which in turn, influenced their optical and photoelectrochemical properties.

Liver histopathological alteration after repeated intra-tracheal instillation of titanium dioxide in male rats

PubMed Central

Suker, Dhamia K.; Jasim, Fatimah A.

2018-01-01

Aim: The present study designed to evaluate the toxic effect of anatase TiO2 NPs on BALF biochemical changes and liver alteration in rats. Background: Titanium dioxide (TiO2) nanoparticles (NPs) are utilized in food color additives and cosmetics worldwide. Humans uptake these nanoparticulate by different routes and may exhibit potential side effects, lags behind the rapid development of nanotechnology. Methods: Sixty-three mats rats were used. Included by the control group and the experimental groups treated twice a week with 0.5, 5, 50, 1.5, 15, 150 mg/kg of nano-TiO2 (size 21 nm), for four consecutive weeks. Animals were sacrificed at 4 days, a month and three months post-instillation. The levels of tumor necrosis factor - α (TNF-α) and macrophage inflammatory protein- 2 (MIP-2) were measured in the lung homogenate and in the bronchoalveolar lavage fluid (BALF) supernatants by enzyme-linked immunosorbent assay (ELISA) and histopathological examination of liver tissue was performed. Results: The results showed that TiO2 NP induces many alterations in the liver structure after 4 days, a month and reduced after 3 months from intratracheal instillation. This included liver heavy infiltration of inflammatory cells, an increase of collagen density in portal triads, beginning of fibrosis formation and Glisson capsule thickness increase and TiO2 NPs reached the liver tissue after a month from exposure at all doses especially low doses (0.5, 1.5, 5) mg/kg of TiO2 NPs. Conclusion: The immune system was strongly responded in the groups treated with high doses (15, 50, 150) mg/kg of TiO2 NP leading to raising the concentration of α-TNF, and MIP-2 in BALF while they decrease in tissue homogenate. PMID:29910858

Interspace modification of titania-nanorod arrays for efficient mesoscopic perovskite solar cells

NASA Astrophysics Data System (ADS)

Chen, Peng; Jin, Zhixin; Wang, Yinglin; Wang, Meiqi; Chen, Shixin; Zhang, Yang; Wang, Lingling; Zhang, Xintong; Liu, Yichun

2017-04-01

Morphology of electron transport layers (ETLs) has an important influence on the device architecture and electronic processes of mesostructured solar cells. In this work, we thoroughly investigated the effect of the interspace of TiO2 nanorod (NR) arrays on the photovoltaic performance of the perovskite solar cells (PSCs). Along with the interspace in TiO2-NR arrays increasing, the thickness as well as the crystal size of perovskite capping layer are reduced accordingly, and the filling of perovskite in the channel becomes incomplete. Electrochemical impedance spectroscopy measurements reveal that this variation of perovskite absorber layer, induced by interspace of TiO2 NR arrays, causes the change of charge recombination process at the TiO2/perovskite interface, suggesting that a balance between capping layer and the perovskite filling is critical to obtain high charge collection efficiency of PSCs. A power conversion efficiency of 10.3% could be achieved through careful optimization of interspace in TiO2-NR arrays. Our research will shed light on the morphology control of ETLs with 1D structure for heterojunction solar cells fabricated by solution-deposited method.

Tuning the Phase and Microstructural Properties of TiO2 Films Through Pulsed Laser Deposition and Exploring Their Role as Buffer Layers for Conductive Films

NASA Astrophysics Data System (ADS)

Agarwal, S.; Haseman, M. S.; Leedy, K. D.; Winarski, D. J.; Saadatkia, P.; Doyle, E.; Zhang, L.; Dang, T.; Vasilyev, V. S.; Selim, F. A.

2018-04-01

Titanium oxide (TiO2) is a semiconducting oxide of increasing interest due to its chemical and thermal stability and broad applicability. In this study, thin films of TiO2 were deposited by pulsed laser deposition on sapphire and silicon substrates under various growth conditions, and characterized by x-ray diffraction (XRD), atomic force microscopy (AFM), optical absorption spectroscopy and Hall-effect measurements. XRD patterns revealed that a sapphire substrate is more suitable for the formation of the rutile phase in TiO2, while a silicon substrate yields a pure anatase phase, even at high-temperature growth. AFM images showed that the rutile TiO2 films grown at 805°C on a sapphire substrate have a smoother surface than anatase films grown at 620°C. Optical absorption spectra confirmed the band gap energy of 3.08 eV for the rutile phase and 3.29 eV for the anatase phase. All the deposited films exhibited the usual high resistivity of TiO2; however, when employed as a buffer layer, anatase TiO2 deposited on sapphire significantly improves the conductivity of indium gallium zinc oxide thin films. The study illustrates how to control the formation of TiO2 phases and reveals another interesting application for TiO2 as a buffer layer for transparent conducting oxides.

Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-05-01

Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

In Vitro Cytotoxicity Assessment of an Orthodontic Composite Containing Titanium-dioxide Nano-particles.

PubMed

Heravi, Farzin; Ramezani, Mohammad; Poosti, Maryam; Hosseini, Mohsen; Shajiei, Arezoo; Ahrari, Farzaneh

2013-01-01

Background and aims. Incorporation of nano-particles to orthodontic bonding systems has been considered to prevent enamel demineralization around appliances. This study investigated cytotoxicity of Transbond XT adhesive containing 1 wt% titanium dioxide (TiO2) nano-particles. Materials and methods. Ten composite disks were prepared from each of the conventional and TiO2-containg composites and aged for 1, 3, 5, 7 and 14 days in Dulbecco's Modified Eagle's Medium (DMEM). The extracts were obtained and exposed to culture media of human gingival fibroblasts (HGF) and mouse L929 fibroblasts. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results. Both adhesives were moderately toxic for HGF cells on the first day of the experiment, but the TiO2-containing adhesive produced significantly lower toxicity than the pure adhesive (P<0.05). No significant differences were found in cell viability percentages between the two groups on the other days (P>0.05). There was a significant reduction in cell toxicity with increasing pre-incubation time (P<0.001). L929 cells showed similar toxicity trends, but lower sensitivity to detect cytotoxicity of dental composites. Conclusion. The orthodontic adhesive containing TiO2 nano-particles indicated comparable or even lower toxicity than its nano-particle-free counterpart, indicating that incorporation of 1 wt% TiO2 nano-particles to the composite structure does not result in additional health hazards compared to that occurring with the pure adhesive.

Agglomeration behaviour of titanium dioxide nanoparticles in river waters: A multi-method approach combining light scattering and field-flow fractionation techniques.

PubMed

Chekli, L; Roy, M; Tijing, L D; Donner, E; Lombi, E; Shon, H K

2015-08-15

Titanium dioxide nanoparticles (TiO2 NPs) are currently one of the most prolifically used nanomaterials, resulting in an increasing likelihood of release to the environment. This is of concern as the potential toxicity of TiO2 NPs has been investigated in several recent studies. Research into their fate and behaviour once entering the environment is urgently needed to support risk assessment and policy development. In this study, we used a multi-method approach combining light scattering and field-flow fractionation techniques to assess both the aggregation behaviour and aggregate structure of TiO2 NPs in different river waters. Results showed that both the aggregate size and surface-adsorbed dissolved organic matter (DOM) were strongly related to the initial DOM concentration of the tested waters (i.e. R(2) > 0.90) suggesting that aggregation of TiO2 NPs is controlled by the presence and concentration of DOM. The conformation of the formed aggregates was also found to be strongly related to the surface-adsorbed DOM (i.e. R(2) > 0.95) with increasing surface-adsorbed DOM leading to more compact structures. Finally, the concentration of TiO2 NPs remaining in the supernatant after sedimentation of the larger aggregates was found to decrease proportionally with both increasing IS and decreasing DOM concentration, resulting in more than 95% sedimentation in the highest IS sample. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of the biosynthesis and signaling pathway of ecdysterone on silkworm (Bombyx mori) following exposure to titanium dioxide nanoparticles.

PubMed

Li, Fanchi; Gu, Zhiya; Wang, Binbin; Xie, Yi; Ma, Lie; Xu, Kaizun; Ni, Min; Zhang, Hua; Shen, Weide; Li, Bing

2014-08-01

Silkworm (Bombyx mori), a model Lepidoptera insect, is economically important. Its growth and development are regulated by endogenous hormones. During the process of transition from larvae to pupae, 20-hydroxyecdysone (20E) plays an important role. The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to their unintentional release into the environment. We investigated the effects of exposure to titanium dioxide nanoparticles (TiO2 NPs) on the action of 20E in B. mori. Titanium dioxide nanoparticle treatment shortened the molting duration by 8 hr and prolonged the molting peak period by 10 %. Solexa sequencing profiled the changes in gene expression in the brain of fifth-instar B. mori in response to TiO2NPS exposure for 72 hr, to address the effects on hormone metabolism and regulation. Thirty one genes were differentially expressed. The transcriptional levels of pi3k and P70S6K, which are involved in the target of the rapamycin (TOR) signaling pathway, were up-regulated. Transcriptional levels of four cytochrome P450 genes, which are involved in 20E biosynthesis, at different developmental stages (48, 96, 144, and 192 hr) at 5th instars of all displayed trends of increasing expression. Simultaneously, the ecdysterone receptors, also displayed increasing trends. The 20E titers at four developmental stages during the 5th instar were 1.26, 1.23, 1.72, and 2.16 fold higher, respectively, than the control group. These results indicate that feeding B. mori with TiO2 NPs stimulates 20E biosynthesis, shortens the developmental progression, and reduces the duration of molting. Thus, application of TiO2 NPs is of high significance for saving the labor force in sericulture, and our research provides a reference for the ecological problems in the field of Lepidoptera exposured to titanium dioxide nanoparticles.

Mitochondrial dysfunction and loss of glutamate uptake in primary astrocytes exposed to titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Wilson, Christina L.; Natarajan, Vaishaali; Hayward, Stephen L.; Khalimonchuk, Oleh; Kidambi, Srivatsan

2015-11-01

Titanium dioxide (TiO2) nanoparticles are currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTracker® Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 +/- 10.56 ppm, 136.0 +/- 31.73 ppm and 62.37 +/- 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of a loss in vital astrocyte function. TiO2 nanoparticles also induced an increase in reactive oxygen species generation, and a decrease in mitochondrial membrane potential, suggesting mitochondrial damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticle exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticle exposure has potential implications in astrocyte-mediated neurological dysfunction.Titanium dioxide (TiO2) nanoparticles are currently the second most produced engineered nanomaterial in the world with vast usage in consumer products leading to recurrent human exposure. Animal studies indicate significant nanoparticle accumulation in the brain while cellular toxicity studies demonstrate negative effects on neuronal cell viability and function. However, the toxicological effects of nanoparticles on astrocytes, the most abundant cells in the brain, have not been extensively investigated. Therefore, we determined the sub-toxic effect of three different TiO2 nanoparticles (rutile, anatase and commercially available P25 TiO2 nanoparticles) on primary rat cortical astrocytes. We evaluated some events related to astrocyte functions and mitochondrial dysregulation: (1) glutamate uptake; (2) redox signaling mechanisms by measuring ROS production; (3) the expression patterns of dynamin-related proteins (DRPs) and mitofusins 1 and 2, whose expression is central to mitochondrial dynamics; and (4) mitochondrial morphology by MitoTracker® Red CMXRos staining. Anatase, rutile and P25 were found to have LC50 values of 88.22 +/- 10.56 ppm, 136.0 +/- 31.73 ppm and 62.37 +/- 9.06 ppm respectively indicating nanoparticle specific toxicity. All three TiO2 nanoparticles induced a significant loss in glutamate uptake indicative of a loss in vital astrocyte function. TiO2 nanoparticles also induced an increase in reactive oxygen species generation, and a decrease in mitochondrial membrane potential, suggesting mitochondrial damage. TiO2 nanoparticle exposure altered expression patterns of DRPs at low concentrations (25 ppm) and apoptotic fission at high concentrations (100 ppm). TiO2 nanoparticle exposure also resulted in changes to mitochondrial morphology confirmed by mitochondrial staining. Collectively, our data provide compelling evidence that TiO2 nanoparticle exposure has potential implications in astrocyte-mediated neurological dysfunction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03646a

Nanoindentation study of the mechanical behavior of TiO2 nanotube arrays

NASA Astrophysics Data System (ADS)

Xu, Y. N.; Liu, M. N.; Wang, M. C.; Oloyede, A.; Bell, J. M.; Yan, C.

2015-10-01

Titanium dioxide (TiO2) nanotube arrays are attracting increasing attention for use in solar cells, lithium-ion batteries, and biomedical implants. To take full advantage of their unique physical properties, such arrays need to maintain adequate mechanical integrity in applications. However, the mechanical performance of TiO2 nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO2 nanotube arrays using the nanoindentation technique. We found that the load-displacement response of the arrays strongly depends on the indentation depth and indenter shape. Substrate-independent elastic modulus and hardness can be obtained when the indentation depth is less than 2.5% of the array height. The deformation mechanisms of TiO2 nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO2 nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed.

Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

PubMed

Zarrin, Saviz; Heshmatpour, Felora

2018-06-05

In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

Efficacy of larvicidal activity of green synthesized titanium dioxide nanoparticles using Mangifera indica extract against blood-feeding parasites.

PubMed

Rajakumar, Govindasamy; Rahuman, Abdul Abdul; Roopan, Selvaraj Mohana; Chung, Ill-Min; Anbarasan, Karunanithi; Karthikeyan, Viswanathan

2015-02-01

Titanium dioxide nanoparticles (TiO2 NPs) are considered to be among the best photocatalytic materials due to their long-term thermodynamic stability, strong oxidizing power, and relative non-toxicity. Nano-preparations with TiO2 NPs are currently under investigation as novel treatments for acne vulgaris, recurrent condyloma acuminata, atopic dermatitis, hyperpigmented skin lesions, and other non-dermatologic diseases. The present study was to investigate the acaricidal and larvicidal activity of synthesized TiO2 NPs utilizing leaf aqueous extract of Mangifera indica L. (Anacardiaceae) against hematophagous parasites. The anti-parasitic activity of TiO2 NPs against the larvae of Rhipicephalus (Boophilus) microplus, Hyalomma anatolicum anatolicum and Haemaphysalis bispinosa (Acari: Ixodidae), fourth instar larvae of Anopheles subpictus, and Culex quinquefasciatus (Diptera: Culicidae) were assessed. The green synthesized TiO2 NPs were analyzed by UV-Vis, FTIR, X-ray diffraction (XRD), AFM, SEM, and TEM. The XRD analysis of synthesized TiO2 NPs revealed the dominant peak at 2θ value of 27.81 which matched the 110 crystallographic plane of the rutile structure indicating the crystal structure. The FTIR spectra exhibited a prominent peak at 3,448 cm(-1) and showed OH stretching due to the alcoholic group, and the OH group may act as a capping agent. The SEM images of TiO2 NPs displayed spherical, oval in shape, individual, and some in aggregates. Characterization of the synthesized TiO2 NPs using AFM offered three-dimensional visualization and uneven surface morphology. The TEM micrograph showed agglomerates, round and slight elongation with an average size of 30 ± 5 nm. The maximum efficacy was observed in synthesized TiO2 NPs against the larvae of R. microplus, Hyalomma anatolicum anatolicum, Haemaphysalis bispinosa, A. subpictus, and Culex quinquefasciatus with LC50 value of 28.56, 33.17, 23.81, 5.84, and 4.34 mg/L, respectively. In the present study, a novel, simple, and eco-friendly approach has been suggested to control blood-feeding parasites.

'Pre-prosthetic use of poly(lactic-co-glycolic acid) membranes treated with oxygen plasma and TiO2 nanocomposite particles for guided bone regeneration processes'.

PubMed

Castillo-Dalí, Gabriel; Castillo-Oyagüe, Raquel; Terriza, Antonia; Saffar, Jean-Louis; Batista-Cruzado, Antonio; Lynch, Christopher D; Sloan, Alastair J; Gutiérrez-Pérez, José-Luis; Torres-Lagares, Daniel

2016-04-01

Guided bone regeneration (GBR) processes are frequently necessary to achieve appropriate substrates before the restoration of edentulous areas. This study aimed to evaluate the bone regeneration reliability of a new poly-lactic-co-glycolic acid (PLGA) membrane after treatment with oxygen plasma (PO2) and titanium dioxide (TiO2) composite nanoparticles. Circumferential bone defects (diameter: 10mm; depth: 3mm) were created on the parietal bones of eight experimentation rabbits and were randomly covered with control membranes (Group 1: PLGA) or experimental membranes (Group 2: PLGA/PO2/TiO2). The animals were euthanized two months afterwards, and a morphologic study was then performed under microscope using ROI (region of interest) colour analysis. Percentage of new bone formation, length of mineralised bone formed in the grown defects, concentration of osteoclasts, and intensity of osteosynthetic activity were assessed. Comparisons among the groups and with the original bone tissue were made using the Kruskal-Wallis test. The level of significance was set in advance at a=0.05. The experimental group recorded higher values for new bone formation, mineralised bone length, and osteoclast concentration; this group also registered the highest osteosynthetic activity. Bone layers in advanced formation stages and low proportions of immature tissue were observed in the study group. The functionalised membranes showed the best efficacy for bone regeneration. The addition of TiO2 nanoparticles onto PLGA/PO2 membranes for GBR processes may be a promising technique to restore bone dimensions and anatomic contours as a prerequisite to well-supported and natural-appearing prosthetic rehabilitations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

NASA Astrophysics Data System (ADS)

Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

2015-06-01

Titanium dioxide (TiO2) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO2-ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs).

Photoproduction of halogens using platinized TiO2

NASA Technical Reports Server (NTRS)

Reichman, B.; Byvik, C. E.

1981-01-01

Unlike electrolysis of halide salt solutions, technique using powdered titanium dioxide catalyst requires no external power other than ultraviolet radiation source. Semiconductor powders photocatalyze and photosynthesize many useful reactions; applications are production of halogen molecules, oxidation of hazardous materials in wastewater, and conversion of carbon monoxide to carbon dioxide.

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes

EPA Science Inventory

Toxicity Assessment of Six Titanium Dioxide Nanoparticles in Human Epidermal Keratinocytes Nanoparticle uptake in cells may be an important determinant of their potential cytotoxic and inflammatory effects. Six commercial TiO2 NP (A=Alfa Aesar,10nm, A*=Alfa Aesar 32nm, B=P25 27...

Nanostructured 2D Diporphyrin Honeycomb Film: Photoelectrochemistry, Photodegradation, and Antibacterial Activity.

PubMed

Zhao, Yuewu; Shang, Qiuwei; Yu, Jiachao; Zhang, Yuanjian; Liu, Songqin

2015-06-10

Surface patterns of well-defined nanostructures play important roles in fabrication of optoelectronic devices and applications in catalysis and biology. In this paper, the diporphyrin honeycomb film, composed of titanium dioxide, protoporphyrin IX, and hemin (TiO2/PPIX/Hem), was synthesized using a dewetting technique with the well-defined polystyrene (PS) monolayer as a template. The TiO2/PPIX/Hem honeycomb film exhibited a higher photoelectrochemical response than that of TiO2 or TiO2/PPIX, which implied a high photoelectric conversion efficiency and a synergistic effect between the two kinds of porphyrins. The TiO2/PPIX/Hem honeycomb film was also a good photosensitizer due to its ability to generate singlet oxygen ((1)O2) under irradiation by visible light. This led to the use of diporphyrin TiO2/PPIX/Hem honeycomb film for the photocatalytic inactivation of bacteria. In addition, the photocatalytic activities of other metal-diporphyrin-based honeycomb films, such as TiO2/MnPPIX/Hem, TiO2/CoPPIX/Hem, TiO2/NiPPIX/Hem, TiO2/CuPPIX/Hem, and TiO2/ZnPPIX/Hem, were investigated. The result demonstrated that the photoelectric properties of diporphyrin-based film could be effectively enhanced by further coupling of porphyrin with metal ions. Such enhanced performance of diporphyrin compounds opened a new way for potential applications in various photoelectrochemical devices and medical fields.

Hydrothermally derived nanoporous titanium dioxide nanorods/nanoparticles and their influence in dye-sensitized solar cell as a photoanode

NASA Astrophysics Data System (ADS)

Rajamanickam, Govindaraj; Narendhiran, Santhosh; Muthu, Senthil Pandian; Mukhopadhyay, Sumita; Perumalsamy, Ramasamy

2017-12-01

Titanium dioxide is a promising wide band gap semiconducting material for dye-sensitized solar cell. The poor electron transport properties still remain a challenge with conventional nanoparticles. Here, we synthesized TiO2 nanorods/nanoparticles by hydrothermal method to improve the charge transport properties. The structural and morphological information of the prepared nanorods/nanoparticles was analysed with X-ray diffraction and electron microscopy analysis, respectively. A high power conversion efficiency of 7.7% is achieved with nanorods/nanoparticles employed device under 100 mW/cm2. From the electrochemical impedance analysis, superior electron transport properties have been found for synthesized TiO2 nanorods/nanoparticles employed device than commercial P25 nanoparticles based device.

Effects of photocatalytic activity of metal and non-metal doped Tio2 for Hydrogen production enhancement - A Review

NASA Astrophysics Data System (ADS)

Nur Aqilah Sulaiman, Siti; Zaky Noh, Mohamad; Nadia Adnan, Nurul; Bidin, Noriah; Razak, Siti Noraiza Ab

2018-05-01

Titanium dioxide TiO2 is well-known materials that has become an efficient photocatalyst for environmental sustainability. Known as solar driven catalysis, TiO2 is considered as the most promising way to alleviate environmental issues caused by the combustion of fossil fuels and to meet worldwide demands for energy. Much effort has been concerned on TiO2 band gap modification to become a visible-light-activated photocatalysts of TiO2 because it can only be excited by UV light irradiation due to its large band gap. Modifications like metals and nonmetals doping has been proposed in the past decades. This reviews survey recent advanced preparation methods of doped-TiO2 including various types of doping methods for various types of dopants and provides general review on further modifications. The characterizations techniques used in order to determine the structural, morphological and optical properties of modified TiO2 is also discussed. Further, a new method of TiO2 modification is proposed in this mini review paper.

A graded catalytic–protective layer for an efficient and stable water-splitting photocathode

DOE PAGES

Gu, Jing; Aguiar, Jeffery A.; Ferrere, Suzanne; ...

2017-01-09

Achieving solar-to-hydrogen efficiencies above 15% is key for the commercial success of photoelectrochemical water splitting devices. While tandem cells can reach those efficiencies, increasing the catalytic activity and long-term stability remains a significant challenge. We show that annealing a bilayer of amorphous titanium dioxide (TiO x) and molybdenum sulfide (MoS x) deposited onto GaInP 2 results in a photocathode with high catalytic activity (current density of 11 mA/cm -2 at 0 V vs. the reversible hydrogen electrode under 1 sun illumination) and stability (retention of 80% of initial photocurrent density over a 20 h durability test) for the hydrogen evolutionmore » reaction. Microscopy and spectroscopy reveal that annealing results in a graded MoS x/MoO x/TiO 2 layer that retains much of the high catalytic activity of amorphous MoS x but with stability similar to crystalline MoS 2. These findings demonstrate the potential of utilizing a hybridized, heterogeneous surface layer as a cost-effective catalytic and protective interface for solar hydrogen production.« less

Application of the UV laser printing technique to soft gelatin capsules containing titanium dioxide in the shells.

PubMed

Hosokawa, Akihiro; Kato, Yoshiteru

2012-03-01

The purpose of this study was to examine application of ultraviolet (UV) laser irradiation to printing soft gelatin capsules containing titanium dioxide (TiO(2)) in the shells and to study effect of UV laser power on the color strength of printing on the soft gelatin capsules. Size 6 Oval type soft gelatin capsules of which shells contained 0.685% TiO(2) and 0.005% ferric dioxide were used in this study. The capsules were irradiated pulsed UV laser at a wavelength 355 nm. The color strength of the printed capsules was determined by a spectrophotometer as total color difference (dE). The soft gelatin capsules which contained TiO(2) in the shells could be printed gray by the laser. Many black particles, which were associated with the printing, were formed at the colored parts of the shells. It was found that there were two inflection points in relationship between output laser energy of a pulse and dE. Below the lower point, the capsules were not printed. From the lower point to the upper point, the capsules were printed gray and total color difference of the printing increased linearly in proportion with the output laser energy. Beyond the upper point, total color difference showed saturation because of micro-bubbles formation at the laser irradiated spot. Soft gelatin capsules containing TiO(2) in the shells could be performed stable printing using the UV laser printing technique. Color strength of the printing could be controlled by regulating the laser energy between the two inflection points.

Titanium: light, strong, and white

USGS Publications Warehouse

Woodruff, Laurel; Bedinger, George

2013-01-01

Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

Effects of atomic oxygen on titanium dioxide thin film

NASA Astrophysics Data System (ADS)

Shimosako, Naoki; Hara, Yukihiro; Shimazaki, Kazunori; Miyazaki, Eiji; Sakama, Hiroshi

2018-05-01

In low earth orbit (LEO), atomic oxygen (AO) has shown to cause degradation of organic materials used in spacecrafts. Similar to other metal oxides such as SiO2, Al2O3 and ITO, TiO2 has potential to protect organic materials. In this study, the anatese-type TiO2 thin films were fabricated by a sol-gel method and irradiated with AO. The properties of TiO2 were compared using mass change, scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmittance spectra and photocatalytic activity before and after AO irradiation. The results indicate that TiO2 film was hardly eroded and resistant against AO degradation. AO was shown to affects only the surface of a TiO2 film and not the bulk. Upon AO irradiation, the TiO2 films were slightly oxidized. However, these changes were very small. Photocatalytic activity of TiO2 was still maintained in spite of slight decrease upon AO irradiation, which demonstrated that TiO2 thin films are promising for elimination of contaminations outgassed from a spacecraft's materials.

Multifunctional Inverse Opal-Like TiO2 Electron Transport Layer for Efficient Hybrid Perovskite Solar Cells.

PubMed

Chen, Xiao; Yang, Shuang; Zheng, Yi Chu; Chen, Ying; Hou, Yu; Yang, Xiao Hua; Yang, Hua Gui

2015-09-01

A novel multifunctional inverse opal-like TiO 2 electron transport layer (IOT-ETL) is designed to replace the traditional compact layer and mesoporous scaffold layer in perovskite solar cells (PSCs). Improved light harvesting efficiency and charge transporting performance in IOT-ETL based PSCs yield high power conversion efficiency of 13.11%.

Antibacterial activity of standard and N-doped titanium dioxide-coated endotracheal tubes: an in vitro study

PubMed Central

Caratto, Valentina; Ball, Lorenzo; Sanguineti, Elisa; Insorsi, Angelo; Firpo, Iacopo; Alberti, Stefano; Ferretti, Maurizio; Pelosi, Paolo

2017-01-01

Objective The aim of this study was to assess the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa of two nanoparticle endotracheal tube coatings with visible light-induced photocatalysis. Methods Two types of titanium dioxide nanoparticles were tested: standard anatase (TiO2) and N-doped TiO2 (N-TiO2). Nanoparticles were placed on the internal surface of a segment of commercial endotracheal tubes, which were loaded on a cellulose acetate filter; control endotracheal tubes were left without a nanoparticle coating. A bacterial inoculum of 150 colony forming units was placed in the endotracheal tubes and then exposed to a fluorescent light source (3700 lux, 300-700 nm wavelength) for 5, 10, 20, 40, 60 and 80 minutes. Colony forming units were counted after 24 hours of incubation at 37°C. Bacterial inactivation was calculated as the percentage reduction of bacterial growth compared to endotracheal tubes not exposed to light. Results In the absence of light, no relevant antibacterial activity was shown against neither strain. For P. aeruginosa, both coatings had a higher bacterial inactivation than controls at any time point (p < 0.001), and no difference was observed between TiO2 and N-TiO2. For S. aureus, inactivation was higher than for controls starting at 5 minutes for N-TiO2 (p = 0.018) and 10 minutes for TiO2 (p = 0.014); inactivation with N-TiO2 was higher than that with TiO2 at 20 minutes (p < 0.001), 40 minutes (p < 0.001) and 60 minutes (p < 0.001). Conclusions Nanosized commercial and N-doped TiO2 inhibit bacterial growth under visible fluorescent light. N-TiO2 has higher antibacterial activity against S. aureus compared to TiO2. PMID:28444073

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bossa, Nathan; Chaurand, Perrine; Levard, Clément

Nanomaterials are increasingly being used to improve the properties and functions of common building materials. A new type of self-cleaning cement incorporating TiO 2 nanomaterials (TiO 2-NMs) with photocatalytic properties is now marketed. This promising cement might provide air pollution-reducing properties but its environmental impact must be validated. During cement use and aging, an altered surface layer is formed that exhibits increased porosity. The surface layer thickness alteration and porosity increase with the cement degradation rate. The hardened cement paste leaching behavior has been fully documented, but the fate of incorporated TiO 2-NMs and their state during/after potential release ismore » currently unknown. In this study, photocatalytic cement pastes with increasing initial porosity were leached at a lab-scale to produce a range of degradation rates concerning the altered layer porosity and thickness. No dissolved Ti was released during leaching, only particulate TiO 2-NM release was detected. The extent of release from this batch test simulating accelerated worst-case scenario was limited and ranged from 18.7 ± 2.1 to 33.5 ± 5.1 mg of Ti/m 2 of cement after 168 h of leaching. TiO 2-NMs released into neutral aquatic media (simulate pH of surface water) were not associated or coated by cement minerals. The TiO 2-NM release mechanism is suspected to start from freeing of TiO 2-NMs in the altered layer pore network due to partial cement paste dissolution followed by diffusion into the bulk pore solution to the surface. The extent of TiO 2-NM release was not solely related to the cement degradation rate.« less

Enhanced photoelectrical performance of dye-sensitized solar cells with double-layer TiO2 on perovskite SrTiO3 substrate

NASA Astrophysics Data System (ADS)

Liu, Qiuhong; Sun, Qiong; Zhang, Min; Li, Yang; Zhao, Mei; Dong, Lifeng

2016-04-01

In this research, perovskite SrTiO3 particles are synthesized by a hydrothermal method, and TiO2 with a double-layer structure is grown on the SrTiO3 surface by a hydrolysis-condensation process. Structural characterizations reveal that TiO2 comprises of two phases: anatase film at the bottom and single-crystal rutile nanorods grown along the [110] direction on top. The TiO2-SrTiO3 composite film is investigated as photoanode material for dye-sensitized solar cells. In comparison with pure TiO2 and SrTiO3, the composite photoanode shows a much better performance in photoelectric conversion efficiency (1.35 %), which is about 2 and 100 times as efficient as pure TiO2 and SrTiO3, respectively. This indicates that the composite structure can facilitate charge carrier transfer and reduce electron-hole recombination to enhance photoelectrical properties of TiO2-based photoanode materials.

Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Zheng, Gaige; Lu, Xi; Qian, Liming; Xian, Fenglin

2017-05-01

In this study, nanocrystalline TiO2 modified ZnO thin films were prepared by electron beam evaporation. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photoluminescent spectrum shows that the pure ZnO thin film exhibits an ultraviolet (UV) emission peak and a strong green emission band. Surface analysis indicates that the ZnO thin film contains many oxygen vacancy defects on the surface. After the ZnO thin film is modified by the nanocrystalline TiO2 layer, the UV emission of ZnO is largely enhanced and the green emission is greatly suppressed, which suggests that the surface defects such as oxygen vacancies are passivated by the TiO2 capping layer. As for the UV emission enhancement of the ZnO thin film, the optimized thickness of the TiO2 capping layer is ∼16 nm. When the thickness is larger than 16 nm, the UV emission of the ZnO thin film will decrease because the TiO2 capping layer absorbs most of the excitation energy. The UV emission enhancement in the nanocrystalline TiO2 modified ZnO thin film can be attributed to surface passivation and flat band effect.

Optical, Electrical, and Crystal Properties of TiO2 Thin Films Grown by Atomic Layer Deposition on Silicon and Glass Substrates

NASA Astrophysics Data System (ADS)

Kupa, I.; Unal, Y.; Cetin, S. S.; Durna, L.; Topalli, K.; Okyay, A. K.; Ates, H.

2018-05-01

TiO2 thin films have been deposited on glass and Si(100) by atomic layer deposition (ALD) technique using tetrakis(diethylamido)titanium(IV) and water vapor as reactants. Thorough investigation of the properties of the TiO2/glass and TiO2/Si thin films was carried out, varying the deposition temperature in the range from 100°C to 250°C while keeping the number of reaction cycles fixed at 1000. Physical and material property analyses were performed to investigate optical and electrical properties, composition, structure, and morphology. TiO2 films grown by ALD may represent promising materials for future applications in optoelectronic devices.

Immobilized TiO2 nanoparticles produced by flame spray for photocatalytic water remediation

NASA Astrophysics Data System (ADS)

Bettini, Luca Giacomo; Diamanti, Maria Vittoria; Sansotera, Maurizio; Pedeferri, Maria Pia; Navarrini, Walter; Milani, Paolo

2016-08-01

Anatase/rutile mixed-phase titanium dioxide (TiO2) photocatalysts in the form of nanostructured powders with different primary particle size, specific surface area, and rutile content were produced from the gas-phase by flame spray pyrolysis (FSP) starting from an organic solution containing titanium (IV) isopropoxide as Ti precursor. Flame spray-produced TiO2 powders were characterized by means of X-ray diffraction, Raman spectroscopy, and BET measurements. As-prepared powders were mainly composed of anatase crystallites with size ranging from 7 to 15 nm according to the synthesis conditions. TiO2 powders were embedded in a multilayered fluoropolymeric matrix to immobilize the nanoparticles into freestanding photocatalytic membranes. The photocatalytic activity of the TiO2-embedded membranes toward the abatement of hydrosoluble organic pollutants was evaluated employing the photodegradation of rhodamine B in aqueous solution as test reaction. The photoabatement rate of best performing membranes significantly overcomes that of membranes produced by the same method and incorporating commercial P25-TiO2.

Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

PubMed Central

Bagheri, Samira; Muhd Julkapli, Nurhidayatullaili; Bee Abd Hamid, Sharifah

2014-01-01

The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2 was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2 supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2 as a support material for heterogeneous catalysts and its potential applications. PMID:25383380

Optimisation of preparation conditions for Ti nanowires and suitability as an antibacterial material.

PubMed

Munisparan, Thivyah; Yang, Evyan Chia Yan; Paramasivam, Ragul; Dahlan, Nuraina Anisa; Pushpamalar, Janarthanan

2018-06-01

Ultrafine titanium dioxide (TiO 2 ) nanowires were synthesised using a hydrothermal method with different volumes of ethylene glycol (EG) and annealing temperatures. It shows that sodium titanate nanowires synthesised using 5 and 10 ml EG, which annealed at 400°C produced TiO 2 nanowires that correspond to a photochemically active phase, which is anatase. The influences of annealing temperatures (400-600°C) on the morphological arrangement of TiO 2 nanowires were evident in the field emission scanning electron microscopy. The annealing temperature of 500°C led to agglomeration, which formed a mixture of TiO 2 nanoparticles and nanowires. High thermal stability of TiO 2 nanowires revealed by thermogravimetric analysis and Fourier transform infrared spectroscopy spectrum showed the presence of the Ti-O-Ti vibrations as evidenced due to TiO 2 lattices. An antibacterial study using TiO 2 nanowires toward Escherichia coli and Klebsiella pneumoniae showed large zones of inhibition that indicated susceptibility of the microbe toward TiO 2 . Growth kinetic analysis shows that addition of TiO 2 has reduced optical density (OD) suggesting an inhibition of the growth of bacteria. These results indicate TiO 2 nanowires can be effectively used as an antimicrobial agent against gram-bacteria. The TiO 2 nanowires could be exploited in the medical, packaging and detergent formulation industries and wastewater treatment.

Computational study of TiO2 Brookite (100), (010) and (210) surface doped with Ruthenium for application in Dye Sensitised Solar Cells

NASA Astrophysics Data System (ADS)

Dima, R. S.; Maluta, N. E.; Maphanga, R. R.; Sankaran, V.

2017-10-01

Titanium dioxide (TiO2) polymorphs are widely used in many energy-related applications due to their peculiar electronic and physicochemical properties. The electronic structures of brookite TiO2 surfaces doped with transition metal ruthenium have been investigated by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The generalized gradient approximation (GGA) was used in the scheme of Perdew-Burke-Ernzerhof (PBE) to describe the exchange-correlation functional. All calculations were carried out with CASTEP (Cambridge Sequential Total EnergyPackage) code in Materials Studio of Accelrys Inc. The surface structures of Ru doped TiO2 were constructed by cleaving the 1 × 1 × 1 optimized bulk structure of brookite TiO2. The results indicate that Ru doping can narrow the band gap of TiO2, leading to the improvement in the photoreactivity of TiO2, and simultaneously maintain strong redox potential. The theoretical calculations could provide meaningful guide to develop more active photocatalysts with visible light response.

Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications

NASA Astrophysics Data System (ADS)

Al-Alwani, Mahmoud A. M.; Mohamad, Abu Bakar; Kadhum, Abd. Amir H.; Ludin, Norasikin A.

2015-03-01

Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.

Atomic layer deposition of TiO2 on nitrogen-doped carbon nanofibers supported Ru nanoparticles for flexible Li-O2 battery: A combined DFT and experimental study

NASA Astrophysics Data System (ADS)

Yang, Jingbo; Mi, Hongwei; Luo, Shan; Li, Yongliang; Zhang, Peixin; Deng, Libo; Sun, Lingna; Ren, Xiangzhong

2017-11-01

Flexible Li-O2 batteries have attracted worldwide research interests and been considered to be potential alternatives for the next-generation flexible devices. Nitrogen-doped carbon nanofibers (N-CNFs) prepared by electrospinning are used as flexible substrate and an amorphous TiO2 layer is coated by atomic layer deposition (ALD) and then decorated with Ru nanoparticles. The Ru/N-CNFs@TiO2 composite is directly used as a free-standing electrode for Li-O2 batteries and the electrode delivers a high specific capacity, improved round-trip efficiency and good cycling ability. The superior electrochemical performance can be attributed to the amorphous TiO2 protecting layer and superior catalytic activity of Ru nanoparticles. Based on density functional theory (DFT) calculations from first principles, the carbon electrode after coating with TiO2 is more stable during discharge/charge process. The analysis of Li2O2 on three different interfaces (Li2O2/N-CNFs, Li2O2/TiO2, and Li2O2/Ru) indicates that the electron transport capacity was higher on Ru and TiO2 compared with N-CNFs, therefore, Li2O2 could be formed and decomposed more easily on the Ru/N-CNFs@TiO2 cathode. This work paves a way to develop the free-standing cathode materials for the future development of high-performance flexible energy storage systems.

Hydrogenated TiO2 nanotube photonic crystals for enhanced photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Meng, Ming; Zhou, Sihua; Yang, Lun; Gan, Zhixing; Liu, Kuili; Tian, Fengshou; Zhu, Yu; Li, ChunYang; Liu, Weifeng; Yuan, Honglei; Zhang, Yan

2018-04-01

We report the design, fabrication and characterization of novel TiO2 nanotube photonic crystals with a crystalline core/disordered shell structure as well as substantial oxygen vacancies for photoelectrochemical (PEC) water splitting. The novel TiO2 nanotube photonic crystals are fabricated by annealing of anodized TiO2 nanotube photonic crystals in hydrogen atmosphere at various temperatures. The optimized novel TiO2 nanotube photonic crystals produce a maximal photocurrent density of 2.2 mA cm-2 at 0.22 V versus Ag/AgCl, which is two times higher that of the TiO2 nanotube photonic crystals annealed in air. Such significant PEC performance improvement can be ascribed to synergistic effects of the disordered surface layer and oxygen vacancies. The reduced band gap owing to the disordered surface layer and localized states induced by oxygen vacancies can enhance the efficient utilization of visible light. In addition, the disordered surface layer and substantial oxygen vacancies can promote the efficiency for separation and transport of the photogenerated carriers. This work may open up new opportunities for the design and construction of the high efficient and low-cost PEC water splitting system.