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Sample records for alginate-coated tio2 sc

  1. Effect of Nb and Sc doping on the phase transformation of sol-gel processed TiO2 nanoparticles.

    PubMed

    Ahmad, A; Buzby, S; Ni, C; Ismat Shah, S

    2008-05-01

    Nb and Sc doped TiO2 nanoparticles were synthesized via sol-gel technique. Dopant concentration of each element was varied from 0.5 to 1.5 atomic%. The effect of metal ion doping and calcination temperatures on anatase to rutile phase transformation has been investigated. Samples were analyzed by various analytical methods such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDS). XRD analyses showed that Nb and Sc doped samples calcined at 300 degrees C and 350 degrees C, respectively, were crystalline and had an anatase structure. Results showed that anatase was stable up to 700 degrees C annealing temperature for samples doped with 0.5 atomic% Nb. There was a sharp transition from anatase to rutile phase above 700 degrees C and complete rutile structure was obtained at 750 degrees C. However, the transformation from anatase to rutile was not so sharp in samples doped with 1.0 atomic% and 1.5 atomic% Nb. Results indicated that higher concentration of Nb helps to stabilize the anatase phase. For samples doped with 0.5 atomic% Sc, anatase phase is stable up to 650 degrees C. Transformation from anatase to rutile starts at temperature above 650 degrees C and 100% rutile phase was obtained at 800 degrees C while for samples doped with 1.0 atomic% and 1.5 atomic% Sc, the complete transformation from anatase to rutile takes place at an even higher temperature. Results indicate that increasing the calcination time from 0.5 to 2.0 hours at 500 degrees C does not affect the stability of anatase phase. However, TEM and XRD data showed that the increase in the annealing time leads to an increase in particles size. The rutile to anatase concentration ratio increased with temperature above the phase transformation temperature. The activation energy for the phase transformation from anatase to rutile for doped and undoped samples was also measured. There was a general rise in

  2. Study of synergistic effect of Sc and C co-doping on the enhancement of visible light photo-catalytic activity of TiO2

    NASA Astrophysics Data System (ADS)

    Nasir, Muhammad; Lei, Juying; Iqbal, Waheed; Zhang, Jinlong

    2016-02-01

    Scandium and carbon co-doped TiO2 catalyst was prepared through a simple sol-gel synthesis method by using scandium nitrate as scandium dopant precursor, glucose as carbon precursor and tetrabutyl orthotitanate as titanium precursor and calcined them at 450 °C for 3 h. The characterizations of the prepared samples were accomplished through X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). The X-ray diffraction results of the samples showed the decrease in the crystal size of the sample with the subsequent increase in the specific surface area as shown by Brunauer-Emmett-Teller. The UV-visible diffuse reflectance spectroscopy displayed the blue shift in the absorption together with the photoluminescence spectroscopy revealed the decrease in the recombination of electrons and holes by the addition of the scandium and then after the certain optimum value, the further increase of the scandium further increased the recombination of electrons and holes. The photo-catalytic activity of the samples was investigated with the help of photo-catalytic degradation of Acid orange 7 under visible light irradiation. The degradation of Acid orange 7 was highly increased for the Sc and C co-doped samples compared to the single C doped sample. And the sample 0.2 Sc/C-TiO2 had the maximum increase. The enhanced photo-catalytic performance was due the decrease of the crystal size, increase of the surface area, increase in the surface hydroxyl groups, and increase of the lifetime of the electrons and holes because of the synergistic effect of the Sc and C co-doping in TiO2.

  3. The Vibrational Frequencies of CaO2, ScO2, and TiO2: A Comparison of Theoretical Methods

    NASA Technical Reports Server (NTRS)

    Rosi, Marzio; Bauschlicher, Charles W., Jr.; Chertihin, George V.; Andrews, Lester; Arnold, James O. (Technical Monitor)

    1997-01-01

    The vibrational frequencies of several states of CaO2, ScO2, and TiO2 are computed at using density functional theory (DFT), the Hatree-Fock approach, second order Moller-Plesset perturbation theory (MP2), and the complete-active-space self-consistent-field theory. Three different functionals are used in the DFT calculations, including two hybrid functionals. The coupled cluster singles and doubles approach including the effect of unlinked triples, determined using perturbation theory, is applied to selected states. The Becke-Perdew 86 functional appears to be the cost effective method of choice, although even this functional does not perform well for one state of CaO2. The MP2 approach is significantly inferior to the DFT approaches.

  4. Alginate-coated magnetic nanoparticles for noninvasive MRI of extracellular calcium.

    PubMed

    Bar-Shir, Amnon; Avram, Liat; Yariv-Shoushan, Shani; Anaby, Debbie; Cohen, Smadar; Segev-Amzaleg, Niva; Frenkel, Dan; Sadan, Ofer; Offen, Daniel; Cohen, Yoram

    2014-07-01

    Nanoparticles (NPs) have great potential to increase the diagnostic capacity of many imaging modalities. MRI is currently regarded as the method of choice for the imaging of deep tissues, and metal ions, such as calcium ions (Ca(2+)), are essential ingredients for life. Despite the tremendous importance of Ca(2+) for the well-being of living systems, the noninvasive determination of the changes in Ca(2+) levels in general, and extracellular Ca(2+) levels in particular, in deep tissues remains a challenge. Here, we describe the preparation and contrast mechanism of a flexible easy to prepare and selective superparamagnetic iron oxide (SPIO) NPs for the noninvasive determination of changes in extracellular Ca(2+) levels using conventional MRI. We show that SPIO NPs coated with monodisperse and purified alginate, having a specific molecular weight, provide a tool to selectively determine Ca(2+) concentrations in the range of 250 µm to 2.5 mm, even in the presence of competitive ions. The alginate-coated magnetic NPs (MNPs) aggregate in the presence of Ca(2+) , which, in turn, affects the T2 relaxation of the water protons in their vicinity. The new alginate-coated SPIO NP formulations, which have no effect on cell viability for 24 h, allow the detection of Ca(2+) levels secreted from ischemic cell cultures and the qualitative examination of the change in extracellular Ca(2+) levels in vivo. These results demonstrate that alginate-coated MNPs can be used, at least qualitatively, as a platform for the noninvasive MRI determination of extracellular Ca(2+) levels in myriad in vitro and in vivo biomedical applications.

  5. Development and characterization of alginate coated low molecular weight chitosan nanoparticles as new carriers for oral vaccine delivery in mice.

    PubMed

    Biswas, Subrata; Chattopadhyay, Mainak; Sen, Kalyan Kumar; Saha, Malay Kumar

    2015-05-01

    In the present study, nanoparticles of low MW chitosan (CS) were formulated in which measles antigen was entrapped and subsequently coated with sodium alginate. The size and surface properties of the nanoparticle can be tuned with different MW of CS. In vitro release studies showed initial burst release followed by extended release, best fitted in the Makoid-Banakar model (R(2)>0.98). SDS-PAGE assay revealed that alginate coating could effectively protect antigen in acidic condition for at least 2h. Cell viability was assessed using MTT assay into HT 29 cell line. Formulations were orally administered to mice and immunological responses were evaluated using ELISA method. Obtained results showed that measles antigen-loaded CS nanoparticles induced strong immune response and significant correlation was observed between the immune response with CS MW. Protecting ability of antigen in gastric environment, sustained release kinetics, systemic and mucosal immune responses and low cytotoxicity observed for the alginate coated nanoparticles demonstrated that LMW CS could be promising platform for oral vaccine delivery. PMID:25659715

  6. Alginate coated chitosan microparticles mediated oral delivery of diphtheria toxoid. Part A. Systematic optimization, development and characterization.

    PubMed

    Shukla, Anshuman; Mishra, Vijay; Bhoop, Bhupinder Singh; Katare, Om Prakash

    2015-11-10

    The current study was embarked upon to develop "optimized" alginate coated chitosan microparticles (ACMs) loaded with Diphtheria toxoid (DTx) employing formulation by design approach. The developed system was characterized for particle size, zeta potential, surface morphology, acidic degradation protection studies, in process stability studies, storage stability studies and in-vivo uptake studies. Microparticles with minimum of average size of 5 μm (PDI, 0.184) were chosen after optimizing the composition and process conditions. The optimized chitosan microparticles were subjected to alginate coating for better protection of loaded antigen till it reached to uptake site i.e. M cells in the Peyer's patches (PPs) and transport of higher amount antigen to the PPs. The zeta-potential values for uncoated chitosan microparticles and ACMs were found to be +29 ± 3.3 mV and -32.6 ± 4.2 mV, respectively. This change of zeta potential, for uncoated to coated, can be explained by the fact that the coating of alginate on chitosan microparticles led to negative side of the zeta potential by virtue of its predominance on the surface. The developed ACMs were able to transport the antigen effectively to the M cell as revealed by confocal laser scanning microscopy. Further, DTx-loaded ACMs demonstrated significant immune responses at serum IgG as well as mucosal sIgA level. PMID:26319633

  7. Electrodeposited Ultrathin TiO2 Blocking Layers for Efficient Perovskite Solar Cells

    PubMed Central

    Su, Tzu-Sen; Hsieh, Tsung-Yu; Hong, Cheng-You; Wei, Tzu-Chien

    2015-01-01

    In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated. PMID:26526771

  8. Electrodeposited Ultrathin TiO2 Blocking Layers for Efficient Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Su, Tzu-Sen; Hsieh, Tsung-Yu; Hong, Cheng-You; Wei, Tzu-Chien

    2015-11-01

    In this study, the electrodeposition (ED) of ultrathin, compact TiO2 blocking layers (BLs) on fluorine-doped tin oxide (FTO) glass for perovskite solar cells (PSCs) is evaluated. This bottom-up method allows for controlling the morphology and thickness of TiO2 films by simply manipulating deposition conditions. Compared with BLs produced using the spin-coating (SC) method, BLs produced using ED exhibit satisfactory surface coverage, even with a film thickness of 29 nm. Evidence from cyclic voltammetry shows that an ED BL suppresses interfacial recombination more profoundly than an SC BL does, consequently improving the photovoltaic properties of the PSC significantly. A PSC equipped with an ED TiO2 BL having a 13.6% power conversion efficiency is demonstrated.

  9. Alginate coated chitosan core shell nanoparticles for oral delivery of enoxaparin: in vitro and in vivo assessment.

    PubMed

    Bagre, Archana Pataskar; Jain, Keerti; Jain, Narendra K

    2013-11-01

    The objective of present research work was to develop alginate coated chitosan core shell nanoparticles (Alg-CS-NPs) for oral delivery of low molecular weight heparin, enoxaparin. Chitosan nanoparticles (CS-NPs) were synthesized by ionic gelation of chitosan using sodium tripolyphosphate. Core shell nanoparticles were prepared by coating CS-NPs with alginate solution under mild agitation. The Alg-CS-NPs were characterized for surface morphology, surface coating, particle size, polydispersity index, zeta potential, drug loading and entrapment efficiency using SEM, Zeta-sizer, FTIR and DSC techniques. Alginate coating increased the size of optimized chitosan nanoparticles from around 213 nm to about 335 nm as measured by dynamic light scattering in zeta sizer and further confirmed by SEM analysis. The performance of optimized enoxaparin loaded Alg-CS-NPs was evaluated by in vitro drug release studies, in vitro permeation study across intestinal epithelium, in vivo venous thrombosis model, particulate uptake by intestinal epithelium using fluorescence microscopy and pharmacokinetic studies in rats. Coating of alginate over the CS-NPs improved the release profile of enoxaparin from the nanoparticles for successful oral delivery. In vitro permeation studies elucidated that more than 75% enoxaparin permeated across the intestinal epithelium with Alg-CS-NPs. The Alg-CS-NPs significantly increased (p<0.05) the oral bioavailability of enoxaparin in comparison to plain enoxaparin solution as revealed by threefold increase in AUC of plasma drug concentration time curve and around 60% reduction in thrombus formation in rat venous thrombosis model. The core shell Alg-CS-NPs showed promising potential for oral delivery and significantly enhanced the in vivo oral absorption of enoxaparin. PMID:23994363

  10. Alginate coated chitosan core shell nanoparticles for oral delivery of enoxaparin: in vitro and in vivo assessment.

    PubMed

    Bagre, Archana Pataskar; Jain, Keerti; Jain, Narendra K

    2013-11-01

    The objective of present research work was to develop alginate coated chitosan core shell nanoparticles (Alg-CS-NPs) for oral delivery of low molecular weight heparin, enoxaparin. Chitosan nanoparticles (CS-NPs) were synthesized by ionic gelation of chitosan using sodium tripolyphosphate. Core shell nanoparticles were prepared by coating CS-NPs with alginate solution under mild agitation. The Alg-CS-NPs were characterized for surface morphology, surface coating, particle size, polydispersity index, zeta potential, drug loading and entrapment efficiency using SEM, Zeta-sizer, FTIR and DSC techniques. Alginate coating increased the size of optimized chitosan nanoparticles from around 213 nm to about 335 nm as measured by dynamic light scattering in zeta sizer and further confirmed by SEM analysis. The performance of optimized enoxaparin loaded Alg-CS-NPs was evaluated by in vitro drug release studies, in vitro permeation study across intestinal epithelium, in vivo venous thrombosis model, particulate uptake by intestinal epithelium using fluorescence microscopy and pharmacokinetic studies in rats. Coating of alginate over the CS-NPs improved the release profile of enoxaparin from the nanoparticles for successful oral delivery. In vitro permeation studies elucidated that more than 75% enoxaparin permeated across the intestinal epithelium with Alg-CS-NPs. The Alg-CS-NPs significantly increased (p<0.05) the oral bioavailability of enoxaparin in comparison to plain enoxaparin solution as revealed by threefold increase in AUC of plasma drug concentration time curve and around 60% reduction in thrombus formation in rat venous thrombosis model. The core shell Alg-CS-NPs showed promising potential for oral delivery and significantly enhanced the in vivo oral absorption of enoxaparin.

  11. Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials.

    PubMed

    Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S G; Ramakrishna, Seeram

    2012-03-01

    Hollow mesoporous one dimensional (1D) TiO(2) nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO(2) nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO(2) nanofibers possess a high surface area of 118 m(2) g(-1) with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO(2) nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η) and short circuit current (J(sc)) are measured as 5.6% and 10.38 mA cm(-2) respectively, which are higher than those of DSSC made using regular TiO(2) nanofibers under identical conditions (η = 4.2%, J(sc) = 8.99 mA cm(-2)). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO(2) nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO(2) nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO(2) nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO(2) nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO(2) nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO(2) nanocatalysts. PMID:22315140

  12. Treatment of TiO2 with COOH-functionalized germanium nanoparticles to enhance the photocurrent of dye-sensitized solar cells.

    PubMed

    Kim, Chang-Ho; Ha, Eun-Sung; Baik, Hionsuck; Kim, Kang-Jin

    2011-03-01

    A dye-sensitized solar cell (DSSC) containing a TiO(2) film treated with COOH-functionalized germanium nanoparticles (Ge-COOH Nps) exhibited a higher short-circuit photocurrent density (J(sc); 15.4 mA cm(-2)) compared to the corresponding untreated DSSC (13.4 mA cm(-2)) using N719 and a 12 μm thick TiO(2) film at 100 mW cm(-2). The amount of N719 attached to the treated TiO(2) film was 21% greater than that attached to the untreated TiO(2) film. Enhancement of the J(sc) value by 15% was attributed mostly to an intramolecular charge transfer from N719 attached to the Ge-COOH Nps to the TiO(2) conduction band through the Ge-COOH Nps.

  13. Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

    PubMed

    Kim, Eun Seong; Kim, Dae-Hwan; Lee, Sang-Ju; Han, Yoon Soo

    2016-03-01

    Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

  14. Optimization of antimicrobial and physical properties of alginate coatings containing carvacrol and methyl cinnamate for strawberry application.

    PubMed

    Peretto, Greta; Du, Wen-Xian; Avena-Bustillos, Roberto J; Berrios, Jose De J; Sambo, Paolo; McHugh, Tara H

    2014-01-29

    Increasing strawberry consumption has led to a growing safety concern because they are not washed after harvest. An antimicrobial edible coating could be an effective postharvest technique to ensure microbial safety and, at the same time, retain overall quality of the fruits. Response surface methodology was used to optimize the antimicrobial activity against Escherichia coli O157:H7 and Botrytis cinerea and several physical properties (turbidity, viscosity, and whitish index) of an alginate coating. A full factorial design was used to select the concentrations of carvacrol and methyl cinnamate on the basis of their effect against E. coli and B. cinerea. A central composite design was then performed to evaluate the effects/interactions of the two antimicrobials on the coating characteristics. The results from analysis of variance showed the significant fitting of all responses to the quadratic model. To attain the desirable responses, the optimal concentrations were 0.98% (w/w) carvacrol and 1.45% (w/w) methyl cinnamate. PMID:24405047

  15. Porous TiO2 Assembled from Monodispersed Nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-03-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending on the further treating temperature. Porous TiO2 nanospheres exhibited enhanced photocatalysis activity compared to the nanoparticles.

  16. Instability of Hydrogenated TiO2

    SciTech Connect

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  17. Conical islands of TiO2 nanotube arrays in the photoelectrode of dye-sensitized solar cells.

    PubMed

    Kim, Woong-Rae; Park, Hun; Choi, Won-Youl

    2015-01-01

    Ti conical island structures were fabricated using photolithography and the reactive ion etching method. The resulting conical island structures were anodized in ethylene glycol solution containing 0.25 wt% NH4F and 2 vol% H2O, and conical islands composed of TiO2 nanotubes were successfully formed on the Ti foils. The conical islands composed of TiO2 nanotubes were employed in photoelectrodes for dye-sensitized solar cells (DSCs). DSC photoelectrodes based on planar Ti structures covered with TiO2 nanotubes were also fabricated as a reference. The short-circuit current (J sc) and efficiency of DSCs based on the conical island structures were higher than those of the reference samples. The efficiency of DSCs based on the conical island structures reached up to 1.866%. From electrochemical impedance spectroscopy and open-circuit voltage (V oc) decay measurements, DSCs based on the conical island structures exhibited a lower charge transfer resistance at the counter cathode and a longer electron lifetime at the interface of the photoelectrode and electrolyte compared to the reference samples. The conical island structure was very effective at improving performances of DSCs based on TiO2 nanotubes. Graphical AbstractConical islands of TiO2 nanotube arrays are fabricated by an anodizing process with Ti protruding dots which have a conical shape. The conical islands are applied for use in DSC photoelectrodes. DSCs based on the conical islands of TiO2 nanotube arrays have the potential to achieve higher efficiency levels compared to DSCs based on normal TiO2 nanotubes and TiO2 nanoparticles because the conical islands of TiO2 nanotube arrays enlarge the surface area for dye adsorption.

  18. Fast removal of malachite green dye using novel superparamagnetic sodium alginate-coated Fe3O4 nanoparticles.

    PubMed

    Mohammadi, Abbas; Daemi, Hamed; Barikani, Mehdi

    2014-08-01

    In this study, superparamagnetic sodium alginate-coated Fe3O4 nanoparticles (Alg-Fe3O4) as a novel magnetic adsorbent were prepared by in situ coprecipitation method, in which Fe3O4 nanoparticles were precipitated from FeCl3 and FeCl2 under alkaline medium in the presence of sodium alginate. The Alg-Fe3O4 nanoparticles were used for removal of malachite green (MG) from aqueous solutions using batch adsorption technique. The characterization of synthesized nanoparticles was performed using XRD, FTIR, TEM, TGA and vibrating sample magnetometer (VSM) techniques. FTIR analysis of synthesized nanoparticles provided the evidence that sodium alginate was successfully coated on the surface of Fe3O4 nanoparticles. The FT-IR and TGA characterization showed that the Alg-Fe3O4 nanoparticles contained about 14% (w/w) of sodium alginate. Moreover, TEM analysis indicated that the average diameter of the Alg-Fe3O4 nanoparticles was about 12nm. The effects of adsorbent dosage, pH and temperature were investigated on the adsorption properties of MG onto Alg-Fe3O4 nanoparticles. The equilibrium adsorption data were modeled using the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 47.84mg/g. The kinetics of adsorption of MG onto Alg-Fe3O4 nanoparticles were investigated using the pseudo-first-order and pseudo-second-order kinetic models. The results showed that the adsorption of MG onto nanoparticles followed pseudo-second-order kinetic model.

  19. Improved performance of Ag-doped TiO2 synthesized by modified sol-gel method as photoanode of dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Gupta, Arun Kumar; Srivastava, Pankaj; Bahadur, Lal

    2016-08-01

    Ag-doped TiO2 with Ag content ranging from 1 to 7 mol% was synthesized by a modified sol-gel route, and its performance as the photoanode of dye-sensitized solar cells (DSSCs) was compared with undoped TiO2 photoanode. Titanium(IV)isopropoxide was used as precursor and hexamethylenetetramine as the capping agent. XRD results show the formation of TiO2 nanoparticles with an average crystallite size of 5 nm (1 % Ag-doped TiO2) and 9 nm (undoped TiO2), respectively. The TiO2 nanopowder was used to prepare its thin film photoelectrode using doctor's blade method. Significant improvement in light-to-energy conversion efficiency was achieved when thin films of 1 % Ag-doped TiO2 were applied as photoanode in DSSC taking N719 as the sensitizer dye. As evidenced by EIS measurements, the electron lifetime of DSSC with Ag-doped TiO2 increased from 1.33 (for undoped TiO2) to 2.05 ms. The short-circuit current density ( J sc), open-circuit voltage ( V oc), fill factor (FF) and the overall energy conversion efficiency ( η) were 1.07 mA cm-2, 0.72 V, 0.73 and 0.40 %, respectively, with the use of 1 % Ag-doped TiO2 photoanode, whereas with undoped TiO2 under similar conditions, J sc = 0.63 mA cm-2, V oc = 0.70 V, fill factor 0.45 and conversion efficiency 0.14 % could be obtained. Therefore, compared with the reference DSSC containing an undoped TiO2 photoanode, the power conversion efficiency of the cell based on Ag-doped TiO2 has been remarkably enhanced by ~70 %. The substantial improvement in the device performance is attributed to the reduced band-gap energy, retarded charge recombination and greater surface coverage of the sensitizing dye over Ag-doped TiO2, which ultimately resulted in improved IPCE, J SC and η values.

  20. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    NASA Astrophysics Data System (ADS)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  1. Photocatalytic degradation of aqueous propoxur solution using TiO2 and Hbeta zeolite-supported TiO2.

    PubMed

    Mahalakshmi, M; Vishnu Priya, S; Arabindoo, Banumathi; Palanichamy, M; Murugesan, V

    2009-01-15

    Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hbeta, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hbeta was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hbeta>HY=H-ZSM-5). TiO2/Hbeta photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hbeta zeolite was monitored using TOC analyzer, HPLC and UV-vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hbeta was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hbeta requires only 480min. TiO2/Hbeta showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively.

  2. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    NASA Astrophysics Data System (ADS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  3. Application of an active alginate coating to control the growth of Listeria monocytogenes on poached and deli turkey products.

    PubMed

    Juck, Greg; Neetoo, Hudaa; Chen, Haiqiang

    2010-09-01

    The relatively high prevalence of Listeria monocytogenes in ready-to-eat (RTE) turkey products is of great concern. The overall objective of this study was to develop antimicrobial edible coating formulations to effectively control the growth of this pathogen. The antimicrobials studied were nisin (500IU/g), Novagard CB 1 (0.25%), Guardian NR100 (500ppm), sodium lactate (SL, 2.4%), sodium diacetate (SD, 0.25%), and potassium sorbate (PS, 0.3%). These were incorporated alone or in binary combinations into five edible coatings: alginate, kappa-carrageenan, pectin, xanthan gum, and starch. The coatings were applied onto the surface of home-style poached and processed deli turkey discs inoculated with ~3log CFU/g of L. monocytogenes. The turkey samples were then stored at 22 degrees C for 7days. For poached and processed deli turkey, the coatings were found to be equally effective, with pectin being slightly less effective than the others. The most effective poached turkey treatments seemed to be SL (2.4%)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%), which yielded final populations of 3.0 and 4.9log CFU/g respectively compared to the control which was 7.9log CFU/g. For processed deli turkey, the most effective antimicrobial treatments seemed to be Nisin (500IU/g)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%) with final populations of 1.5 and 1.7log CFU/g respectively compared to the control which was 6.5log CFU/g. In the second phase of the study, home-style poached and store-purchased roasted (deli) turkey inoculated with the pathogen at a level of ~3log CFU/g were coated with alginate incorporating selected antimicrobial combinations and stored for 8weeks at 4 degrees C. Alginate coatings supplemented with SL (2.4%)/PS (0.3%) delayed the growth of L. monocytogenes with final counts reaching 4.3log CFU/g (home-style poached turkey) and 6.5log CFU/g (roasted deli turkey) respectively while the counts in their untreated counterparts were significantly higher (P<0.05) reaching 9

  4. Application of an active alginate coating to control the growth of Listeria monocytogenes on poached and deli turkey products.

    PubMed

    Juck, Greg; Neetoo, Hudaa; Chen, Haiqiang

    2010-09-01

    The relatively high prevalence of Listeria monocytogenes in ready-to-eat (RTE) turkey products is of great concern. The overall objective of this study was to develop antimicrobial edible coating formulations to effectively control the growth of this pathogen. The antimicrobials studied were nisin (500IU/g), Novagard CB 1 (0.25%), Guardian NR100 (500ppm), sodium lactate (SL, 2.4%), sodium diacetate (SD, 0.25%), and potassium sorbate (PS, 0.3%). These were incorporated alone or in binary combinations into five edible coatings: alginate, kappa-carrageenan, pectin, xanthan gum, and starch. The coatings were applied onto the surface of home-style poached and processed deli turkey discs inoculated with ~3log CFU/g of L. monocytogenes. The turkey samples were then stored at 22 degrees C for 7days. For poached and processed deli turkey, the coatings were found to be equally effective, with pectin being slightly less effective than the others. The most effective poached turkey treatments seemed to be SL (2.4%)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%), which yielded final populations of 3.0 and 4.9log CFU/g respectively compared to the control which was 7.9log CFU/g. For processed deli turkey, the most effective antimicrobial treatments seemed to be Nisin (500IU/g)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%) with final populations of 1.5 and 1.7log CFU/g respectively compared to the control which was 6.5log CFU/g. In the second phase of the study, home-style poached and store-purchased roasted (deli) turkey inoculated with the pathogen at a level of ~3log CFU/g were coated with alginate incorporating selected antimicrobial combinations and stored for 8weeks at 4 degrees C. Alginate coatings supplemented with SL (2.4%)/PS (0.3%) delayed the growth of L. monocytogenes with final counts reaching 4.3log CFU/g (home-style poached turkey) and 6.5log CFU/g (roasted deli turkey) respectively while the counts in their untreated counterparts were significantly higher (P<0.05) reaching 9

  5. Chemical modification of nanometric TiO2 particles by anchoring functional silane molecules in supercritical CO2

    NASA Astrophysics Data System (ADS)

    López-Periago, Ana M.; Sandoval, Wendy; Domingo, Concepción

    2014-03-01

    Supercritical carbon dioxide (scCO2) was used as a green solvent for the grafting of complex functional organosilanes containing nitrogen moieties on titanium dioxide (TiO2) nanoparticles using two strategies. The first strategy involved the preparation of two functional silanes, 4-nitrophenyl-(3-(trimethoxysilyl)-propyl)methanimine (NPTMS) and 4-(((3-(trimethoxysilyl)propyl)imino)methyl)-benzaldehyde (FPTMS) and further deposited under anhydrous conditions and scCO2 onto the TiO2 surface. The second strategy involved the scCO2 anhydrous deposition of bifunctional commercial silanes on the TiO2 surface. Two structures were synthesized. The first consisted in grafted TiO2 nanoparticles prepared by addition of the ligand, ((1R,2R)-N-(pyridin-2-ylmethyl)-2-(((E)-pyridin-2-ylmethylene) amino)-cyclohexan-1-amine (LPy-red), and designated as Ti-Cl-LPy-red. The second structure was synthesized by the reaction of (1,2)-diaminocylohexane (Dac), through the reactive site of 3-(Trimethoxysilyl)propyl methacrylate (MPTMS) previously deposited on the TiO2 surface and designated as Ti-MP-Dac. The synthesized silanes were characterized by ATR-FT and NMR spectroscopies and mass spectrometry. ATR-FT spectroscopy confirmed the presence of the silanes on the surface of the hybrid nanoparticles. Thermogravimetic analysis was used to estimate the loading of the silane grafted through both hydrogen and covalent bonding on the TiO2 surface. Further characterization of the solid samples was done by N2 adsorption-desorption and UV-vis diffuse reflectance.

  6. Photodegradation of Orange II by mesoporous TiO2.

    PubMed

    Kuang, Liyuan; Zhao, Yaping; Liu, Lu

    2011-09-01

    Mesoporous TiO(2) microspheres were prepared by a hydrothermal reaction and are characterized in this paper. Decoloration and mineralization during photodegradation of Orange II by mesoporous TiO(2) at different pH values, formation of sulfate, relative luminosity to luminous bacteria and recycling experiments of the catalyst were studied. The FTIR results further suggested that the novel mesoporous TiO(2) can not only decolor and mineralize dyes completely but also can be effectively reused several times. On the basis of the research, mesoporous TiO(2) would be a promising photocatalyst for practical use. PMID:21833403

  7. Structural investigations of hybrid TiO2/CNTs nanomaterials.

    PubMed

    Lin, Kuan-Nan; Liou, Wei-Jen; Lin, Hong-Ming; Yang, Tsung-Yeh; Lin, Chung-Kwei

    2010-05-01

    In the present study, pure TiO2 and hybrid TiO2/CNTs nanomaterials are prepared by sol gel technique. Post heat treatment is performed at 600, 800, and 1000 degrees C, respectively. The structural characterizations are performed by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and synchrotron X-ray absorption spectroscopy techniques. Experimental results show that anatase to rutile transformation can be observed for pure TiO2 nanomaterials after heat treatment at 800 degrees C. The anatase to rutile transformation is inhibited by carbon nanotubes, and therefore only anatase phases for TiO2 nanomaterials can be observed in the hybrid nanomaterials. The 600 degrees C hybrid nanomaterials show a microstructure with CNTs covered by continuous TiO2 films of numerous small nanoparticles. After applying heat treatment on the hybrid nanomaterials at 1000 degrees C, only TiO2 nanoparticles adhere individually to the uncovered CNTs. Though all hybrid nanomaterials exhibit anatase TiO2, synchrotron X-ray absorption spectra investigations reveal that hybrid TiO2/CNTs exhibit different electronic properties as compared to those of pure TiO2 nanomaterials.

  8. Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.

    PubMed

    Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

    2004-11-15

    TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol.

  9. Effect of TiO2 Particle Size on the Performance of Flexible Dye Sensitized Solar Cells.

    PubMed

    Li, Zhen-yu; Akhtar, M Shaheer; Yang, O-bong

    2015-09-01

    The size TiO2 nanoparticles was controlled by changing the concentration of titanium tetraisopropanolate (TTIP) and utilized as light scattering particles in the efficient flexible photoelectrodes for flexible dye sensitized solar cells (DSSCs). The flexible photoelectrodes were prepared by TiO2 nanoparticles (-25 nm) paste with different concentrations of ethanolic TTIP solution. The addition of TTIP produced the bigger TiO2 nanoparticles, which significantly enhanced the dye absorption of flexible TiO2 photoelectrode. The fabricated flexible DSSCs showed the reasonable conversion efficiency of 2.50% with short circuit current (J(sc)) of 6.3 mA/cm2, open circuit voltage (V(oc)) of 0.720 V and fill factor (FF) of 0.55. The improvement in photovoltaic performance with 25 wt% TTIP might due to uniform distribution of small TiO2 nanoparticles over the big particles to lead the enhancement in the surface area, resulting in the high dye absorption and light harvesting efficiency. PMID:26716227

  10. Photovoltaic performance of nanoporous TiO2 replicas synthesized from mesoporous materials for dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Yoo, Seung-Joon; Kim, Sung-Soo; Kim, Ji-Man; Shim, Wang-Geun; Kim, Sun-Il; Lee, Jae-Wook

    2008-10-01

    For dye-sensitized solar cell (DSSC), highly ordered nanoporous TiO2 materials with crystalline frameworks were successfully synthesized from different silica templates including SBA-15, KIT-6 and MSU-H. A photoelectrode in DSSC was fabricated by adsorbing cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)bis-tetrabutylammonium dye (N719) onto the prepared TiO2 nanoparticles. The samples were characterized by XRD, TEM, FE-SEM, AFM and Brunauer-Emmett-Teller (BET), and FT-IR analysis. An investigation of the influence of the bonding structure of N719 dye and nanoporous TiO2 on the photovoltaic performance of DSSC revealed that the bonding structure of N719 on TiO2 films is caused by the unidentate and bidentate linkage. Based on the overall conversion efficiency (eta), fill factor (FF), open-circuit voltage (V(oc)) and short-circuit current (/sc) from the I-V curves measured, it was observed that the photoelectric performance is strongly dependent on the dispersion properties of the nanoporous TiO2 replicas from mesoporous silica templates.

  11. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis. PMID:23536037

  12. Graphene-embedded 3D TiO2 inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement.

    PubMed

    Kim, Hye-Na; Yoo, Haemin; Moon, Jun Hyuk

    2013-05-21

    We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO2 matrix via post-treatment of the TiO2 precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO2 inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO2 inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.

  13. Acetaldehyde photochemistry on TiO2(110)

    SciTech Connect

    Zehr, Robert T.; Henderson, Michael A.

    2008-07-01

    The ultraviolet (UV) photon induced decomposition of acetaldehyde absorbed on the oxidized retile TIO2(110) surface was studied with photon stimulated desorption (PSD) and theral programmed desorption (TPD). Acetaldehyde desorbs molecularly from TiO2(110) with minor decomposition channels yielding butene on the reduced TiO2 surface and acetate on the oxidized TiO2 surface. Acetaldehyde absorbed on oxidized TiO2(110) undergoes a facile thermal reaction to form a photoactive acetaldehyde-oxygen complex. UV irradiation of the acetaldehyde-oxygen complex resulting in the ejection of methyl radical into gas phase and conversion of the surface bound fragment to formate.

  14. Acetaldehyde Photochemistry on TiO2(110)

    SciTech Connect

    Zehr, Robert T.; Henderson, Michael A.

    2008-07-01

    The ultraviolet (UV) photon induced decomposition of acetaldehyde adsorbed on the oxidized rutile TiO2(110) surface was studied with photon stimulated desorption (PSD) and thermal programmed desorption (TPD). Acetaldehyde desorbs molecularly from TiO2(110) with minor decomposition channels yielding butene on the reduced TiO2 surface and acetate on the oxidized TiO2 surface. Acetaldehyde adsorbed on oxidized TiO2(110) undergoes a facile thermal reaction to form a photoactive acetaldehyde-oxygen complex. UV irradiation of the acetaldehyde-oxygen complex initiated photofragmentation of the complex resulting in the ejection of methyl radical into gas phase and conversion of the surface bound fragment to formate.

  15. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  16. Preparation and photocatalytic activity of bicrystal phase TiO2 nanotubes containing TiO2-B and anatase

    NASA Astrophysics Data System (ADS)

    Huang, Chuanxi; Zhu, Kerong; Qi, Mengyao; Zhuang, Yonglong; Cheng, Chao

    2012-06-01

    Bicrystal phase TiO2 nanotubes (NTS) containing monoclinic TiO2-B and anatase were prepared by the hydrothermal reaction of anatase nanoparticles with NaOH aqueous solution and a heat treatment. Their structure was characterized by XRD, TEM and Raman spectra. The results showed that the bicrystal phase TiO2 NTS were formed after calcining H2Ti4O9·H2O NTS at 573 K. The bicrystal phase TiO2 NTS exhibit significantly higher photocatalytic activity than the single phase anatase NTS and Dessuga P-25 nanoparticles in the degradation of Methyl Orange aqueous solution under ultraviolet light irradiation, which is attributed to the large surface and interface areas of the bicrystal phase TiO2 NTS.

  17. Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

    2014-01-01

    Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 μm of the Cu-polymer coating to 206 μm of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

  18. Growth of TiO2 nanoparticles under heat treatment

    NASA Astrophysics Data System (ADS)

    Bahadur, J.; Sen, D.; Mazumder, S.; Sastry, P. U.; Paul, B.

    2013-02-01

    The effect of heat treatment, on growth of NiO doped TiO2, have been investigated. The nanoparticle size has been estimated by small-angle x-ray scattering. The average particle size increases with increasing temperature. The growth of crystallite size has been probed by X-ray diffraction. A polymorphic phase transition of TiO2 is observed beyond 600°C due to growth of TiO2 nanoparticles beyond 14 nm of size.

  19. Low temperature crystallisation of mesoporous TiO2.

    PubMed

    Kohn, Peter; Pathak, Sandeep; Stefik, Morgan; Ducati, Caterina; Wiesner, Ulrich; Steiner, Ullrich; Guldin, Stefan

    2013-11-01

    Conducting mesoporous TiO2 is rapidly gaining importance for green energy applications. To optimise performance, its porosity and crystallinity must be carefully fine-tuned. To this end, we have performed a detailed study on the temperature dependence of TiO2 crystallisation in mesoporous films. Crystal nucleation and growth of initially amorphous TiO2 derived by hydrolytic sol-gel chemistry is compared to the evolution of crystallinity from nanocrystalline building blocks obtained from non-hydrolytic sol-gel chemistry, and mixtures thereof. Our study addresses the question whether the critical temperature for crystal growth can be lowered by the addition of crystalline nucleation seeds.

  20. TiO2-graphene nanocomposites for gas-phase photocatalytic degradation of volatile aromatic pollutant: is TiO2-graphene truly different from other TiO2-carbon composite materials?

    PubMed

    Zhang, Yanhui; Tang, Zi-Rong; Fu, Xianzhi; Xu, Yi-Jun

    2010-12-28

    The nanocomposites of TiO(2)-graphene (TiO(2)-GR) have been prepared via a facile hydrothermal reaction of graphene oxide and TiO(2) in an ethanol-water solvent. We show that such a TiO(2)-GR nanocomposite exhibits much higher photocatalytic activity and stability than bare TiO(2) toward the gas-phase degradation of benzene, a volatile aromatic pollutant in air. By investigating the effect of different addition ratios of graphene on the photocatalytic activity of TiO(2)-GR systematically, we find that the higher weight ratio in TiO(2)-GR will decrease the photocatalytic activity. Analogous phenomenon is also observed for the liquid-phase degradation of dyes over TiO(2)-GR. In addition, the key features for TiO(2)-GR including enhancement of adsorptivity of pollutants, light absorption intensity, electron-hole pairs lifetime, and extended light absorption range have also been found in the composite of TiO(2) and carbon nanotubes (TiO(2)-CNT). These strongly manifest that TiO(2)-GR is in essence the same as other TiO(2)-carbon (carbon nanotubes, fullerenes, and activated carbon) composite materials on enhancement of photocatalytic activity of TiO(2), although graphene by itself has unique structural and electronic properties. Notably, this key fundamental question remains completely unaddressed in a recent report ( ACS Nano 2010 , 4 , 380 ) regarding liquid-phase degradation of dyes over the TiO(2)-GR photocatalyst. Thus, we propose that TiO(2)-GR cannot provide truly new insights into the fabrication of TiO(2)-carbon composite as high-performance photocatalysts. It is hoped that our work could avert the misleading message to the readership, hence offering a valuable source of reference on fabricating TiO(2)-carbon composites for their application as a photocatalyst in the environment cleanup. PMID:21117654

  1. Combined Embedding of N/F-Doping and CaCO3 Surface Modification in the TiO2 Photoanode for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2016-03-01

    N/F-doping and CaCO3 surface modification was carried out in TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The combined effect of the N/F doped TiO2 and the CaCO3 coating showed a great increase of the short-circuit current (J(sc)), and photoelectric conversion efficiency (η) of the prepared cells; the efficiency (η) was improved from 7.00% of a commercial TiO2 photoelectrode to 7.90% of an uncoated N/F-doped electrode, and to 9.09% of a N/F-doped and CaCO3 surface modified electrode. An enhanced photoresponse in N/F-doped TiO2 nanoparticles generate more photo-excited electrons, as supported by measured UV-Vis diffuse reflectance spectra. A successive CaCO3 surface modification then forms a barrier on the surface of the N/F-doped TiO2 particles; the higher basicity of the CaCO3 modified TiO2 facilitates the dye adsorption, as supported by the direct measurement of the amount of adsorbed dye.

  2. Combined Embedding of N/F-Doping and CaCO3 Surface Modification in the TiO2 Photoanode for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2016-03-01

    N/F-doping and CaCO3 surface modification was carried out in TiO2 photoelectrodes for dye-sensitized solar cells (DSSCs). The combined effect of the N/F doped TiO2 and the CaCO3 coating showed a great increase of the short-circuit current (J(sc)), and photoelectric conversion efficiency (η) of the prepared cells; the efficiency (η) was improved from 7.00% of a commercial TiO2 photoelectrode to 7.90% of an uncoated N/F-doped electrode, and to 9.09% of a N/F-doped and CaCO3 surface modified electrode. An enhanced photoresponse in N/F-doped TiO2 nanoparticles generate more photo-excited electrons, as supported by measured UV-Vis diffuse reflectance spectra. A successive CaCO3 surface modification then forms a barrier on the surface of the N/F-doped TiO2 particles; the higher basicity of the CaCO3 modified TiO2 facilitates the dye adsorption, as supported by the direct measurement of the amount of adsorbed dye. PMID:27455671

  3. 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...

  4. Photocatalytic metamaterials: TiO2 inverse opals.

    PubMed

    Sordello, Fabrizio; Duca, Clara; Maurino, Valter; Minero, Claudio

    2011-06-01

    The study of the photocatalytic activity of TiO(2) inverse opals showed that these structures behave as metamaterials: their properties arise principally from the 3D periodic structure of the material and marginally from porosity, reflectivity and scattering.

  5. Investigation of physical properties of TiO2 nanolayers

    NASA Astrophysics Data System (ADS)

    Struk, Przemyslaw; Pustelny, Tadeusz

    2015-12-01

    We present applications of titanium dioxide wide bandgap oxide semiconductor and its application in integrated optics devices. The paper is focus on research of physical properties TiO2 such as: spectral transmittance, refractive index, extinction coefficient in the UV-VIS-IR range of light as well as surface topography. In addition we show the numerical calculation and optical characterization of fabricated optical planar waveguide based on TiO2.

  6. Density functional theory study of interactions between glycine and TiO2/graphene nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Meng-hao; Guo, Ya-nan; Wang, Qun; Zhang, Xia-shi-yao; Huang, Jing-jing; Lu, Xiong; Wang, Ke-feng; Zhang, Hong-ping; Leng, Yang

    2014-04-01

    The interactions of glycine (Gly) with TiO2, graphene (G), graphene oxide (GO), TiO2/G and TiO2/GO nanocomposites were investigated by density functional theory (DFT). The results indicate that the interactions between Gly and TiO2 in TiO2/G nanocomposites are stronger than that between Gly and bare TiO2 surfaces, which suggests G helps to strengthen the interaction of amino acids with TiO2 surfaces. In TiO2/GO nanocomposites, the interactions of Gly and TiO2 are slightly weaker than that between Gly and bare TiO2 surfaces, which reveals that GO is not conducive to the interaction of amino acids with TiO2 surfaces.

  7. TiO2 optical sensor for amino acid detection

    NASA Astrophysics Data System (ADS)

    Tereshchenko, Alla; Viter, Roman; Konup, Igor; Ivanitsa, Volodymyr; Geveliuk, Sergey; Ishkov, Yuriy; Smyntyna, Valentyn

    2013-11-01

    A novel optical sensor based on TiO2 nanoparticles for Valine detection has been developed. In the presented work, commercial TiO2 nanoparticles (Sigma Aldrich, particle size 32 nm) were used as sensor templates. The sensitive layer was formed by a porphyrin coating on a TiO2 nanostructured surface. As a result, an amorphous layer between the TiO2 nanostructure and porphyrin was formed. Photoluminescence (PL) spectra were measured in the range of 370-900 nm before and after porphyrin application. Porphyrin adsorption led to a decrease of the main TiO2 peak at 510 nm and the emergence of an additional peak of high intensity at 700 nm. Absorption spectra (optical density vs. wavelenght, measured from 300 to 1100 nm) showed IR shift Sorret band of prophiryn after deposition on metal oxide. Adsorption of amino acid quenched PL emission, related to porphyrin and increased the intensity of the TiO2 emission. The interaction between the sensor surface and the amino acid leads to the formation of new complexes on the surface and results in a reduction of the optical activity of porphyrin. Sensitivity of the sensor to different concentrations of Valine was calculated. The developed sensor can determine the concentration of Valine in the range of 0.04 to 0.16 mg/ml.

  8. Optimization of process parameters for removal of heavy metals by biomass of Cu and Co-doped alginate-coated chitosan nanoparticles.

    PubMed

    Esmaeili, Akbar; Khoshnevisan, Najmeh

    2016-10-01

    In this study, the efficiency of alginate-coated chitosan nanoparticles (Alg-CS-NPs) for removal of heavy metals from industrial effluents was investigated. To this end, the researchers constructed a reactor containing biomass, using response surface methodology (RSM) for process optimization. Reactor tests were carried out with both synthetic and industrial effluents containing nickel. The optimum conditions to achieve maximum removal efficiency (RE) rates for both synthetic and industrial effluents were specified for contact time (0-120min), pH level (1-9), biomass dose (0.1-0.9g), and initial metal ion concentration (10-90mg/L). It was determined that 94.48% of the nickel could be removed at pH=3, 70mg/L initial nickel concentration, a dose of 0.3g biomass, and 30min contact time. The kinetic data fit well to a pseudo second-order model and the equilibrium data of the metal ions could be described well with Freundlich isotherm models.

  9. Formation of iron(III) (hydr)oxides on polyaspartate- and alginate-coated substrates: effects of coating hydrophilicity and functional group.

    PubMed

    Ray, Jessica R; Lee, Byeongdu; Baltrusaitis, Jonas; Jun, Young-Shin

    2012-12-18

    To better understand the transport of contaminants in aqueous environments, we need more accurate information about heterogeneous and homogeneous nucleation of iron(III) hydroxide nanoparticles in the presence of organics. We combined synchrotron-based grazing incidence small-angle X-ray scattering (GISAXS) and SAXS and other nanoparticle and substrate surface characterization techniques to observe iron(III) (hydr)oxide [10⁻⁴ M Fe(NO₃)₃ in 10 mM NaNO₃] precipitation on quartz and on polyaspartate- and alginate-coated glass substrates and in solution (pH = 3.7 ± 0.2). Polyaspartate was determined to be the most negatively charged substrate and quartz the least; however, after 2 h, total nanoparticle volume calculations--from GISAXS--indicate that positively charged precipitation on quartz is twice that of alginate and 10 times higher than on polyaspartate, implying that electrostatics do not govern iron(III) (hydr)oxide nucleation. On the basis of contact angle measurements and surface characterization, we concluded that the degree of hydrophilicity may control heterogeneous nucleation on quartz and organic-coated substrates. The arrangement of functional groups at the substrate surface (--OH and --COOH) may also contribute. These results provide new information for elucidating the effects of polymeric organic substrate coatings on the size, volume, and location of nucleating iron hydroxides, which will help predict nanoparticle interactions in natural and engineered systems.

  10. Effect of sodium alginate coating enriched with horsemint (Mentha longifolia) essential oil on the quality of bighead carp fillets during storage at 4°C.

    PubMed

    Heydari, Ramin; Bavandi, Shahmir; Javadian, Seyed Roholla

    2015-05-01

    Effect of sodium alginate coating enriched with horsemint essential oil (HEO) on the quality of bighead carp (Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate (SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly (P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA. PMID:25987993

  11. Effect of sodium alginate coating enriched with horsemint (Mentha longifolia) essential oil on the quality of bighead carp fillets during storage at 4°C.

    PubMed

    Heydari, Ramin; Bavandi, Shahmir; Javadian, Seyed Roholla

    2015-05-01

    Effect of sodium alginate coating enriched with horsemint essential oil (HEO) on the quality of bighead carp (Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate (SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly (P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA.

  12. Effect of sodium alginate coating enriched with horsemint (Mentha longifolia) essential oil on the quality of bighead carp fillets during storage at 4°C

    PubMed Central

    Heydari, Ramin; Bavandi, Shahmir; Javadian, Seyed Roholla

    2015-01-01

    Effect of sodium alginate coating enriched with horsemint essential oil (HEO) on the quality of bighead carp (Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate (SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly (P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA. PMID:25987993

  13. Structural, Optical and Thermal Investigations of TiO2 and S-Doped TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Divyanshu; Kumar, Ashavani

    2011-12-01

    Titanium dioxide (TiO2) and sulfur doped titanium dioxide (S-doped TiO2) nanoparticles are synthesized by Coprecipitation technique using titanium trichloride (TiCl3) as precursor, ammonium hydroxide (NH4OH) as solvent and sodium sulfite as source of sulfur. The X-ray diffraction (xrd) pattern reveals that TiO2 Nanoparticles are in anatase phase and anatase content decreases with increasing S-doping. The Differential Scanning Calorimetry (DSC) analysis elucidates the metastable anatase phase changes to stable rutile phase at 746 °C temperature. The UV/Vis study predicts larger band gap of TiO2 Nanoparticles as compare to bulk and blue shift with increasing S-doping.

  14. TiO2 (B) nanosheets mediate phase selective synthesis of TiO2 nanostructured photocatalyst

    NASA Astrophysics Data System (ADS)

    Wang, Yuxi; Wang, Changhua; Zhang, Xintong; Sun, Panpan; Kong, Lina; Wei, Yongan; Zheng, Han; Liu, Yichun

    2014-02-01

    Phase selective synthesis is particularly valuable in revealing performance of photocatalyst existing as several polymorphic phases. In this work, we develop a general soft chemical route that used a TiO2 (B) nanosheet as a precursor to synthesize TiO2 nanostructures of desired phase. Benefiting from the structural similarity and ultrathin thickness feature, TiO2 (B) nanosheet precursor can readily transform to pure phase of anatase, rutile and brookite as well as mixed phase of brookite/anatase. A possible dissolution-recrystallization mechanism is proposed for the phase transition of TiO2 (B) nanosheets to other phases. Photocatalytic activity tests demonstrated that the brookite/anatase mixture had the highest activity in degrading acetaldehyde under UV light irradiation, due to the synergistic effect of high crystallinity, large surface area and mixed phase structure.

  15. Selective aerobic oxidation mediated by TiO(2) photocatalysis.

    PubMed

    Lang, Xianjun; Ma, Wanhong; Chen, Chuncheng; Ji, Hongwei; Zhao, Jincai

    2014-02-18

    TiO2 is one of the most studied metal oxide photocatalysts and has unparal-leled efficiency and stability. This cheap, abundant, and non-toxic material has the potential to address future environmental and energy concerns. Understanding about the photoinduced interfacial redox events on TiO2 could have profound effect on the degradation of organic pollutants, splitting of H2O into H2 and O2, and selective redox organic transformations. Scientists traditionally accept that for a semiconductor photocatalyst such as TiO2 under the illumination of light with energy larger than its band gap, two photocarriers will be created to carry out their independent reduction and oxidation processes. However, our recent discoveries indicate that it is the concerted rather than independent effect of both photocarriers of valence band hole (hvb(+)) and conduction band electron (ecb(-)) that dictate the product formation during interfacial oxidation event mediated by TiO2 photocatalysis. In this Account, we describe our recent findings on the selective oxidation of organic substrates with O2 mediated by TiO2 photocatalysis. The transfer of O-atoms from O2 to the corresponding products dominates the selective oxidation of alcohols, amines, and alkanes mediated by TiO2 photocatalysis. We ascribe this to the concerted effect of both hvb(+) and ecb(-) of TiO2 in contribution to the oxidation products. These findings imply that O2 plays a unique role in its transfer into the products rather than independent role of ecb(-) scavenger. More importantly, ecb(-) plays a crucial role to ensure the high selectivity for the oxygenation of organic substrates. We can also use the half reactions such as those of the conduction band electron of TiO2 for efficient oxidation reactions with O2. To this end, efficient selective oxidation of organic substrates such as alcohols, amines, and aromatic alkanes with O2 mediated by TiO2 photocatalysis under visible light irradiation has been achieved. In summary, the concerted effect of hvb(+) and ecb(-) to implement one oxidation event could pave the way for selective oxofunctionalization of organic substrates with O2 by metal oxide photocatalysis. Furthermore, it could also deepen our understanding on the role of O2 and the elusive nature of oxygen species at the interface of TiO2, which, in turn, could shed new light on avant-garde photocatalytic selective redox processes in addressing the energy and environmental challenges of the future.

  16. Selective aerobic oxidation mediated by TiO(2) photocatalysis.

    PubMed

    Lang, Xianjun; Ma, Wanhong; Chen, Chuncheng; Ji, Hongwei; Zhao, Jincai

    2014-02-18

    TiO2 is one of the most studied metal oxide photocatalysts and has unparal-leled efficiency and stability. This cheap, abundant, and non-toxic material has the potential to address future environmental and energy concerns. Understanding about the photoinduced interfacial redox events on TiO2 could have profound effect on the degradation of organic pollutants, splitting of H2O into H2 and O2, and selective redox organic transformations. Scientists traditionally accept that for a semiconductor photocatalyst such as TiO2 under the illumination of light with energy larger than its band gap, two photocarriers will be created to carry out their independent reduction and oxidation processes. However, our recent discoveries indicate that it is the concerted rather than independent effect of both photocarriers of valence band hole (hvb(+)) and conduction band electron (ecb(-)) that dictate the product formation during interfacial oxidation event mediated by TiO2 photocatalysis. In this Account, we describe our recent findings on the selective oxidation of organic substrates with O2 mediated by TiO2 photocatalysis. The transfer of O-atoms from O2 to the corresponding products dominates the selective oxidation of alcohols, amines, and alkanes mediated by TiO2 photocatalysis. We ascribe this to the concerted effect of both hvb(+) and ecb(-) of TiO2 in contribution to the oxidation products. These findings imply that O2 plays a unique role in its transfer into the products rather than independent role of ecb(-) scavenger. More importantly, ecb(-) plays a crucial role to ensure the high selectivity for the oxygenation of organic substrates. We can also use the half reactions such as those of the conduction band electron of TiO2 for efficient oxidation reactions with O2. To this end, efficient selective oxidation of organic substrates such as alcohols, amines, and aromatic alkanes with O2 mediated by TiO2 photocatalysis under visible light irradiation has been achieved. In summary, the concerted effect of hvb(+) and ecb(-) to implement one oxidation event could pave the way for selective oxofunctionalization of organic substrates with O2 by metal oxide photocatalysis. Furthermore, it could also deepen our understanding on the role of O2 and the elusive nature of oxygen species at the interface of TiO2, which, in turn, could shed new light on avant-garde photocatalytic selective redox processes in addressing the energy and environmental challenges of the future. PMID:24164388

  17. Lithium insertion in nanostructured TiO(2)(B) architectures.

    PubMed

    Dylla, Anthony G; Henkelman, Graeme; Stevenson, Keith J

    2013-05-21

    Electric vehicles and grid storage devices have potentialto become feasible alternatives to current technology, but only if scientists can develop energy storage materials that offer high capacity and high rate capabilities. Chemists have studied anatase, rutile, brookite and TiO2(B) (bronze) in both bulk and nanostructured forms as potential Li-ion battery anodes. In most cases, the specific capacity and rate of lithiation and delithiation increases as the materials are nanostructured. Scientists have explained these enhancements in terms of higher surface areas, shorter Li(+) diffusion paths and different surface energies for nanostructured materials allowing for more facile lithiation and delithiation. Of the most studied polymorphs, nanostructured TiO2(B) has the highest capacity with promising high rate capabilities. TiO2(B) is able to accommodate 1 Li(+) per Ti, giving a capacity of 335 mAh/g for nanotubular and nanoparticulate TiO2(B). The TiO2(B) polymorph, discovered in 1980 by Marchand and co-workers, has been the focus of many recent studies regarding high power and high capacity anode materials with potential applications for electric vehicles and grid storage. This is due to the material's stability over multiple cycles, safer lithiation potential relative to graphite, reasonable capacity, high rate capability, nontoxicity, and low cost (Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem., Int. Ed.2008, 47, 2930-2946). One of the most interesting properties of TiO2(B) is that both bulk and nanostructured forms lithiate and delithiate through a surface redox or pseudocapacitive charging mechanism, giving rise to stable high rate charge/discharge capabilities in the case of nanostructured TiO2(B). When other polymorphs of TiO2 are nanostructured, they still mainly intercalate lithium through a bulk diffusion-controlled mechanism. TiO2(B) has a unique open crystal structure and low energy Li(+) pathways from surface to subsurface sites, which many chemists believe to contribute to the pseudocapacitive charging. Several disadvantages exist as well. TiO2(B), and titania in general, suffers from poor electronic and ionic conductivity. Nanostructured TiO2(B) also exhibits significant irreversible capacity loss (ICL) upon first discharge (lithiation). Nanostructuring TiO2(B) can help alleviate problems with poor ionic conductivity by shortening lithium diffusion pathways. Unfortunately, this also increases the likelihood of severe first discharge ICL due to reactive Ti-OH and Ti-O surface sites that can cause unwanted electrolyte degradation and irreversible trapping of Li(+). Nanostructuring also results in lowered volumetric energy density, which could be a considerable problem for mobile applications. We will also discuss these problems and proposed solutions. Scientists have synthesized TiO2(B) in a variety of nanostructures including nanowires, nanotubes, nanoparticles, mesoporous-ordered nanostructures, and nanosheets. Many of these structures exhibit enhanced Li(+) diffusion kinetics and increased specific capacities compared to bulk material, and thus warrant investigation on how nanostructuring influences lithiation behavior. This Account will focus on these influences from both experimental and theoretical perspectives. We will discuss the surface charging mechanism that gives rise to the increased lithiation and delithiation kinetics for TiO2(B), along with the influence of dimensional confinement of the nanoarchitectures, and how nanostructuring can change the lithiation mechanism considerably. PMID:23425042

  18. Au-loaded TiO2 and Ag-loaded TiO2 synthesized by modified sol-gel/impregnation method as photocatalysts

    NASA Astrophysics Data System (ADS)

    Ninsonti, Hathaithip; Sriwichai, Saengrawee; Wetchakun, Natda; Kangwansupamonkon, Wiyong; Phanichphant, Sukon

    2016-02-01

    In this work, Au-loaded TiO2 and Ag-loaded TiO2 nanoparticles were synthesized by modified sol-gel method together with impregnation method. The samples were characterized by their physicochemical properties using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy in order to obtain the correlation between structure and photocatalytic properties. XRD results indicated unloaded TiO2, Au-loaded TiO2 and Ag-loaded TiO2 nanoparticles were all in the anatase phase with average crystallite size in the range of 10-13 nm. In addition, XPS analysis confirmed the presence of Au and Ag elements in Au-loaded TiO2 and Ag-loaded TiO2 nanoparticles, respectively. The photocatalytic activities of TiO2, Au-loaded TiO2 and Ag-loaded TiO2 nanoparticles were evaluated through the mineralization of formic acid under UV-light illumination. The results showed that Au-loading and Ag-loading could effectively improve the photocatalytic activities of TiO2. Furthermore, Au-loaded TiO2 exhibited a higher photocatalytic activity than Ag-loaded TiO2.

  19. Photocatalytic performance of TiO2-zeolite templated carbon composites in organic contaminant degradation.

    PubMed

    Donphai, Waleeporn; Kamegawa, Takashi; Chareonpanich, Metta; Nueangnoraj, Khanin; Nishihara, Hirotomo; Kyotani, Takashi; Yamashita, Hiromi

    2014-12-01

    TiO2 composites with zeolite templated carbon (TiO2-ZTC) and activated carbon (TiO2-AC) were prepared and used as the photocatalysts for comparative studies with pure TiO2. TiO2-ZTC exhibited the highest rate of methylene blue degradation with a rate approximately 4 and 400 times higher than those of TiO2-AC and pure TiO2, respectively. Moreover, the highest catalytic performance of TiO2-ZTC in gas-phase degradation of acetone was approximately 1.1 and 12.9 times higher than TiO2-AC and pure TiO2, respectively. These outstanding performances could be attributed to high surface area, pore volume, and hydrophobic surface properties, leading to improvement in the adsorption properties of organic molecules.

  20. Wet chemical synthesis and self-assembly of SnS2 nanoparticles on TiO2 for quantum dot-sensitized solar cells.

    PubMed

    Tsukigase, Hiroki; Suzuki, Yoshikazu; Berger, Marie-Hélène; Sagawa, Takashi; Yoshikawa, Susumu

    2011-04-01

    SnS2 nanoparticles were synthesized through a simple wet chemical process at room temperature. The SnS2 nanoparticles were approximately spherical in shape and had diameter about 3-4 nm. SnS2-sensitized TiO2 electrodes were fabricated by the immersion of chemically modified TiO2 to well-dispersed SnS2 solution for 72 h (i.e., self-assembly method.) SnS2-sensitized TiO2 electrodes were applied in quantum dot-sensitized solar cells (QDSSCs). Under AM1.5 irradiation with 100 mW/cm2 light intensity (at 1 sun), the short-circuit current density (J(sc)), the open-circuit voltage (V(oc)), the fill factor (FF), and the energy conversion efficiency (eta) were 0.47 mA/cm2, 0.29 V, 0.58 and 0.081%, respectively.

  1. Photocatalytic Properties of TiO2 Porous Network Film.

    PubMed

    Yu, Lianqing; Zhi, Qianqian; Huang, Chengxing; Zhang, Yaping; Dong, Kaituo; Neppolian, B

    2015-09-01

    Three-dimensional porous network TiO2 film (PW-film) and nanoparticles film were synthesized on surface of the Ti foil by a facile method to investigate both the photoelectrochemical and photocatalytic properties. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction spectroscopy (XRD) techniques. Methylene blue was used as a target molecule to estimate the photocatalytic activity of the films. Results revealed that the hydrothermal temperature and time have great influence on the crystal type and film morphology of TiO2 catalysts. A higher hydrothermal temperature is benefit for the formation of anatase phase of TiO2 nanotubes with PW-film, which had a large number of nodes. After investigation of the photoelectrochemical properties, a maximum photoconversion efficiency of 4.79% is observed for nanoparticles film with rutile phase of TiO2 under UV light illumination, which was incredible 2 times higher than that of the PW-film with anatase phase. It was shown that the morphology of TiO2 film contributes more significant effect on photocatalytic and photoelectric performance than its crystal type. PMID:26716214

  2. Photocatalytic Properties of TiO2 Porous Network Film.

    PubMed

    Yu, Lianqing; Zhi, Qianqian; Huang, Chengxing; Zhang, Yaping; Dong, Kaituo; Neppolian, B

    2015-09-01

    Three-dimensional porous network TiO2 film (PW-film) and nanoparticles film were synthesized on surface of the Ti foil by a facile method to investigate both the photoelectrochemical and photocatalytic properties. The prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction spectroscopy (XRD) techniques. Methylene blue was used as a target molecule to estimate the photocatalytic activity of the films. Results revealed that the hydrothermal temperature and time have great influence on the crystal type and film morphology of TiO2 catalysts. A higher hydrothermal temperature is benefit for the formation of anatase phase of TiO2 nanotubes with PW-film, which had a large number of nodes. After investigation of the photoelectrochemical properties, a maximum photoconversion efficiency of 4.79% is observed for nanoparticles film with rutile phase of TiO2 under UV light illumination, which was incredible 2 times higher than that of the PW-film with anatase phase. It was shown that the morphology of TiO2 film contributes more significant effect on photocatalytic and photoelectric performance than its crystal type.

  3. Hydrogen Impurity Defects in Rutile TiO2

    PubMed Central

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-01-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy. PMID:26627134

  4. Hydrogen Impurity Defects in Rutile TiO2

    NASA Astrophysics Data System (ADS)

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-12-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy.

  5. Quasiparticle Interfacial Level Alignment of Highly Hybridized Frontier Levels: H2O on TiO2(110)

    SciTech Connect

    Migani, Annapaola; Mowbray, Duncan J.; Zhao, Jin; Petek, Hrvoje

    2015-01-13

    Knowledge of the frontier levels’ alignment prior to photoirradiation is necessary to achieve a complete quantitative description of H2O photocatalysis on TiO2(110). Although H2O on rutile TiO2(110) has been thoroughly studied both experimentally and theoretically, a quantitative value for the energy of the highest H2O occupied levels is still lacking. For experiment, this is due to the H2O levels being obscured by hybridization with TiO2(110) levels in the difference spectra obtained via ultraviolet photoemission spectroscopy (UPS). For theory, this is due to inherent difficulties in properly describing many-body effects at the H2O–TiO2(110) interface. Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) G0W0, we disentangle the adsorbate and surface contributions to the complex UPS spectra of H2O on TiO2(110). We perform this separation as a function of H2O coverage and dissociation on stoichiometric and reduced surfaces. Due to hybridization with the TiO2(110) surface, the H2O 3a1 and 1b1 levels are broadened into several peaks between 5 and 1 eV below the TiO2(110) valence band maximum (VBM). These peaks have both intermolecular and interfacial bonding and antibonding character. We find the highest occupied levels of H2O adsorbed intact and dissociated on stoichiometric TiO2(110) are 1.1 and 0.9 eV below the VBM. We also find a similar energy of 1.1 eV for the highest occupied levels of H2O when adsorbed dissociatively on a bridging O vacancy of the reduced surface. In both cases, these energies are significantly higher (by 0.6 to 2.6 eV) than those estimated from UPS difference spectra, which are inconclusive in this energy region. Finally, we apply self-consistent QPGW (scQPGW1) to obtain the ionization potential of the H2O–TiO2(110) interface.

  6. Quasiparticle interfacial level alignment of highly hybridized frontier levels: H2O on TiO2(110).

    PubMed

    Migani, Annapaola; Mowbray, Duncan J; Zhao, Jin; Petek, Hrvoje

    2015-01-13

    Knowledge of the frontier levels' alignment prior to photoirradiation is necessary to achieve a complete quantitative description of H2O photocatalysis on TiO2(110). Although H2O on rutile TiO2(110) has been thoroughly studied both experimentally and theoretically, a quantitative value for the energy of the highest H2O occupied levels is still lacking. For experiment, this is due to the H2O levels being obscured by hybridization with TiO2(110) levels in the difference spectra obtained via ultraviolet photoemission spectroscopy (UPS). For theory, this is due to inherent difficulties in properly describing many-body effects at the H2O-TiO2(110) interface. Using the projected density of states (DOS) from state-of-the-art quasiparticle (QP) G0W0, we disentangle the adsorbate and surface contributions to the complex UPS spectra of H2O on TiO2(110). We perform this separation as a function of H2O coverage and dissociation on stoichiometric and reduced surfaces. Due to hybridization with the TiO2(110) surface, the H2O 3a1 and 1b1 levels are broadened into several peaks between 5 and 1 eV below the TiO2(110) valence band maximum (VBM). These peaks have both intermolecular and interfacial bonding and antibonding character. We find the highest occupied levels of H2O adsorbed intact and dissociated on stoichiometric TiO2(110) are 1.1 and 0.9 eV below the VBM. We also find a similar energy of 1.1 eV for the highest occupied levels of H2O when adsorbed dissociatively on a bridging O vacancy of the reduced surface. In both cases, these energies are significantly higher (by 0.6 to 2.6 eV) than those estimated from UPS difference spectra, which are inconclusive in this energy region. Finally, we apply self-consistent QPGW (scQPGW1) to obtain the ionization potential of the H2O-TiO2(110) interface. PMID:26574222

  7. Electrorheological Response of POLYANILINE-TIO2 Composite Suspensions

    NASA Astrophysics Data System (ADS)

    Sung, J. H.; Lee, I.; Choi, H. J.; Choi, S. B.

    As an organic/inorganic hybrid possessing advantages from the combination of their own unique properties, conducting polyaniline (PANI)-titanium dioxide (TiO2) hybrid particles were synthesized by an oxidation polymerization of aniline, and their ER characteristics were examined. Our aim was to study the ER behavior of highly potential ER-active particles using conducting polymer and TiO2 nanoparticle with relatively high dielectric constant. In addition, we also investigated its ER behavior as a function of particle fraction of TiO2 under an applied electric field. The result was interpreted in terms of the dielectric relaxation mismatch. The fast relaxation time of PANI/TiO2 hybrid was considered to enhance electrostatic force over shear force under a hydrodynamic flow, showing its improved ER performance.

  8. Different methods in TiO2 photodegradation mechanism studies: gaseous and TiO2-adsorbed phases.

    PubMed

    Deveau, Pierre-Alexandre; Arsac, Fabrice; Thivel, Pierre-Xavier; Ferronato, Corinne; Delpech, Françoise; Chovelon, Jean-Marc; Kaluzny, Pascal; Monnet, Christine

    2007-06-18

    The development of photocatalysis processes offers a significant number of perspectives especially in gaseous phase depollution. It is proved that the photo-oxidizing properties of photocatalyst (TiO(2)) activated by UV plays an important role in the degradation of volatile organic compounds (VOC). Heterogeneous photocatalysis is based on the absorption of UV radiations by TiO(2). This phenomenon leads to the degradation and the oxidation of the compounds, according to a mechanism that associates the pollutant's adsorption on the photocatalyst and radical degradation reactions. The main objective of the study is the understanding of the TiO(2)-photocatalysis phenomenon including gaseous and adsorbed phase mechanisms. Results obtained with three different apparatus are compared; gaseous phases are analysed and mechanisms at the gaseous phase/photocatalyst interface are identified. This study leads to improve understanding of various mechanisms during pollutant photodegradation: adsorption of pollutants on TiO(2) first takes place, then desorption and/or photodegradation, and finally, desorption of degradation products on TiO(2). The association of analytical methods and different processes makes the determination of all parameters that affect the photocatalytic process possible. Mastering these parameters is fundamental for the design and construction of industrial size reactors that aim to purify the atmosphere.

  9. A Surface Science Perspective on TiO2 Photocatalysis

    SciTech Connect

    Henderson, Michael A.

    2011-06-15

    The field of surface science provides a unique approach to understanding bulk, surface and interfacial phenomena occurring during TiO2 photochemistry and photocatalysis. This review highlights, from a surface science perspective, recent literature providing molecular-level insights into phonon-initiated events on TiO2 surfaces obtained in seven key scientific issues: (1) photon absorption, (2) charge transport and trapping, (3) electron transfer dynamics, (4) the adsorbed state, (5) mechanisms, (6) poisons and promoters, and (7) phase and form.

  10. The role of surface modification for TiO2 nanoparticles in cancer cells.

    PubMed

    Xie, Jin; Pan, Xiaobo; Wang, Mengyan; Ma, Jiong; Fei, Yiyan; Wang, Pei-Nan; Mi, Lan

    2016-07-01

    Titanium dioxide nanoparticles (TiO2 NPs) have a potential in the field of biological application. However, its poor dispersibility in water hampered its applications. In this study, 3-phosphonopropionic acid and 3-aminopropyl-triethoxysilane were respectively used for surface modification on TiO2 NPs with negative and positive surface charges (denoted as TiO2-COOH and TiO2-NH2). Zeta potentials of the prepared samples with high absolute value demonstrate the great improvement in their dispersibility. In terms of viability experiment, both TiO2-COOH and TiO2-NH2 showed low cytotoxicity. The cellular uptake efficiency and the uptake pathways of TiO2-COOH and TiO2-NH2 for cancer cells were studied. The exocytosis of TiO2-NH2 was also observed in the experiment. PMID:27003465

  11. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    PubMed Central

    Che Ramli, Zatil Amali; Asim, Nilofar; Isahak, Wan N. R. W.; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M. Ambar; Sopian, K.

    2014-01-01

    This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC), TiO2/carbon (C), and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC) was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TG-DTA), Brunauer-Emmet-Teller (BET), and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1). The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples. PMID:25013855

  12. Electrochemical characterization of TiO2/WOx nanotubes for photocatalytic application

    PubMed Central

    2014-01-01

    TiO2/WOx nanotubes have unique photo-energy retention properties that have gathered scientific interest. Herein, we report the synthesis, morphological characterization, and the electrochemical characterization of TiO2/WOx nanotubes compared with pure TiO2 nanotubes, prepared by anodization technique. Significant structural differences were not observed in TiO2/WOx nanotubes as observed by using scanning electron microscopy and transmission electron microscopy. The charge transfer resistance of TiO2/WOx before and after photo irradiation determined by using electrochemical impedance spectroscopy proves the inherent energy retention property which was not observed in pure TiO2 nanotubes. PMID:25346647

  13. Nano TiO2 Composite PVDF Polymer Electrolyte

    NASA Astrophysics Data System (ADS)

    Chiang, Chin-Yeh; Chu, Peter P.

    2002-12-01

    Physical and transport properties of lithium ion conducting polymer electrolyte formed by dispersing nanoscale particles and tubes of TiO2 into poly (vinyl dine fluoride) (PVDF) - lithium salt complexes are discussed. The composite in polymer is enhancing the interfacial interaction, ionic conductivity and mechanical strength due to the high surface area of the particle and the tube. DSC studies elucidate that both the crystallinity and melting temperatures of PVDF are decreased with increasing salt content. Blending with TiO2 particles also decreases melting temperature and crystallinity of PVDF, however nano-tube TiO2 shows even more dramatic effects compared to the particles in reducing PVDF crystallinity and the melting temperature. Even with the improved miscibility and higher salt dissociation, the ionic conductivities is reduced for the TiO2 nano particle composite, but increased about 20 fold in the nano-tube composite. The discrepancies are related to the difference of morphology as evidence from SEM micrograph.

  14. Doping of TiO2 for sensitized solar cells.

    PubMed

    Roose, Bart; Pathak, Sandeep; Steiner, Ullrich

    2015-11-21

    This review gives a detailed summary and evaluation of the use of TiO2 doping to improve the performance of dye sensitized solar cells. Doping has a major effect on the band structure and trap states of TiO2, which in turn affect important properties such as the conduction band energy, charge transport, recombination and collection. The defect states of TiO2 are highly dependent on the synthesis method and thus the effect of doping may vary for different synthesis techniques, making it difficult to compare the suitability of different dopants. High-throughput methods may be employed to achieve a rough prediction on the suitability of dopants for a specific synthesis method. It was however found that nearly every employed dopant can be used to increase device performance, indicating that the improvement is not so much caused by the dopant itself, as by the defects it eliminates from TiO2. Furthermore, with the field shifting from dye sensitized solar cells to perovskite solar cells, the role doping can play to further advance this emerging field is also discussed.

  15. ALMA observations of TiO2 around VY CMa

    NASA Astrophysics Data System (ADS)

    De Beck, Elvire; Vlemmings, Wouter; Muller, Sébastien; Black, John H.; O'Gorman, Eamon; Richards, Anita M. S.; Baudry, Alain; Maercker, Matthias; Decin, Leen; Humphreys, Elizabeth M.

    2016-07-01

    Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. We present and discuss the detections of 15 emission lines of TiO2 with ALMA in the complex environment of the red supergiant VY CMa. The observations reveal a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. We find evidence for a roughly east-west oriented, accelerating bipolar-like structure, of which the blue component runs into and breaks up around a solid continuum component. We see a distinct tail to the south-west for some transitions, consistent with features seen in the optical and near-infrared. We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa.

  16. Protein Corona Prevents TiO2 Phototoxicity

    PubMed Central

    Garvas, Maja; Testen, Anze; Umek, Polona; Gloter, Alexandre; Koklic, Tilen; Strancar, Janez

    2015-01-01

    Background & Aim TiO2 nanoparticles have generally low toxicity in the in vitro systems although some toxicity is expected to originate in the TiO2-associated photo-generated radical production, which can however be modulated by the radical trapping ability of the serum proteins. To explore the role of serum proteins in the phototoxicity of the TiO2 nanoparticles we measure viability of the exposed cells depending on the nanoparticle and serum protein concentrations. Methods & Results Fluorescence and spin trapping EPR spectroscopy reveal that the ratio between the nanoparticle and protein concentrations determines the amount of the nanoparticles’ surface which is not covered by the serum proteins and is proportional to the amount of photo-induced radicals. Phototoxicity thus becomes substantial only at the protein concentration being too low to completely coat the nanotubes’ surface. Conclusion These results imply that TiO2 nanoparticles should be applied with ligands such as proteins when phototoxic effects are not desired - for example in cosmetics industry. On the other hand, the nanoparticles should be used in serum free medium or any other ligand free medium, when phototoxic effects are desired – as for efficient photodynamic cancer therapy. PMID:26083725

  17. Photocatalytic bacterial inactivation by TiO2-coated surfaces.

    PubMed

    Bonetta, Silvia; Bonetta, Sara; Motta, Francesca; Strini, Alberto; Carraro, Elisabetta

    2013-01-01

    The aim of this study was the evaluation of the photoactivated antibacterial activity of titanium dioxide (TiO2)-coated surfaces. Bacterial inactivation was evaluated using TiO2-coated Petri dishes. The experimental conditions optimized with Petri dishes were used to test the antibacterial effect of TiO2-coated ceramic tiles. The best antibacterial effect with Petri dishes was observed at 180, 60, 30 and 20 min of exposure for Escherichia coli, Staphylococcus aureus, Pseudomonas putida and Listeria innocua, respectively. The ceramic tiles demonstrated a photoactivated bactericidal effect at the same exposure time. In general, no differences were observed between the antibacterial effect obtained with Petri dishes and tiles. However, the photochemical activity of Petri dishes was greater than the activity of the tiles.Results obtained indicates that the TiO2-coated surfaces showed a photoactivated bactericidal effect with all bacteria tested highlighting that the titania could be used in the ceramic and building industry for the production of coated surfaces to be placed in microbiologically sensitive environments, such as the hospital and food industry.

  18. Rose Bengal sensitized bilayered photoanode of nano-crystalline TiO2-CeO2 for dye-sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Sayyed, Suhail A. A. R.; Beedri, Niyamat I.; Kadam, Vishal S.; Pathan, Habib M.

    2016-08-01

    The present work deals with the study of TiO2-CeO2 bilayered photoanode with low-cost Rose Bengal (RB) dye as sensitizer for dye-sensitized solar cell application. The recombination reactions are reduced in bilayered TiO2-CeO2 photoanode as compared to the single-layered CeO2 photoanode. Once the electrons get transferred from lowest unoccupied molecular orbital level of RB dye to the conduction band (CB) of TiO2, then the possibilities of recombination of electrons with oxidized dye molecules or oxidized redox couple are reduced. This is because the CB position of CeO2 is higher than that of TiO2, which blocks the path of electrons. The electrochemical impedance spectroscopy (EIS) analysis shows negative shift in frequency for bilayered TiO2-CeO2 photoanode as compared to CeO2 photoanode. Hence, in bilayered photoanode lifetime of electrons is more than in single-layered photoanode, confirming reduction in recombination reactions. The X-ray diffraction patterns confirm both anatase TiO2 and CeO2 with crystalline size using Scherrer formula as 24 and 10 nm, respectively. The scanning electron microscopy images of photoanode show the porous structure useful for dye adsorption. The presence of Ti and Ce is confirmed by electron diffraction studies. The band gap values for TiO2 and CeO2 were calculated as 3.20 and 3.11 eV, respectively, using diffused reflectance spectroscopy. The bilayered TiO2-CeO2 photoanode showed open-circuit voltage ( V OC) ~500 mV and short-circuit photocurrent density ( J SC) ~0.29 mA/cm2 with fill factor (FF) ~62.17 %. There is increase in V OC and J SC values by 66.67 and 38.10 %, respectively, compared to RB-sensitized CeO2 photoanode.

  19. Fate of pristine TiO2 nanoparticles and aged paint-containing TiO2 nanoparticles in lettuce crop after foliar exposure.

    PubMed

    Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Trcera, Nicolas; Sorieul, Stéphanie; Cécillon, Lauric; Ouerdane, Laurent; Legros, Samuel; Sarret, Géraldine

    2014-05-30

    Engineered TiO2 nanoparticles (TiO2-NPs) are present in a large variety of consumer products, and are produced in largest amount. The building industry is a major sector using TiO2-NPs, especially in paints. The fate of NPs after their release in the environment is still largely unknown, and their possible transfer in plants and subsequent impacts have not been studied in detail. The foliar transfer pathway is even less understood than the root pathway. In this study, lettuces were exposed to pristine TiO2-NPs and aged paint leachate containing TiO2-NPs and microparticles (TiO2-MPs). Internalization and in situ speciation of Ti were investigated by a combination of microscopic and spectroscopic techniques. Not only TiO2-NPs pristine and from aged paints, but also TiO2-MPs were internalized in lettuce leaves, and observed in all types of tissues. No change in speciation was noticed, but an organic coating of TiO2-NPs is likely. Phytotoxicity markers were tested for plants exposed to pristine TiO2-NPs. No acute phytotoxicity was observed; variations were only observed in glutathione and phytochelatin levels but remained low as compared to typical values. These results obtained on the foliar uptake mechanisms of nano- and microparticles are important in the perspective of risk assessment of atmospheric contaminations. PMID:24709478

  20. Fate of pristine TiO2 nanoparticles and aged paint-containing TiO2 nanoparticles in lettuce crop after foliar exposure.

    PubMed

    Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Trcera, Nicolas; Sorieul, Stéphanie; Cécillon, Lauric; Ouerdane, Laurent; Legros, Samuel; Sarret, Géraldine

    2014-05-30

    Engineered TiO2 nanoparticles (TiO2-NPs) are present in a large variety of consumer products, and are produced in largest amount. The building industry is a major sector using TiO2-NPs, especially in paints. The fate of NPs after their release in the environment is still largely unknown, and their possible transfer in plants and subsequent impacts have not been studied in detail. The foliar transfer pathway is even less understood than the root pathway. In this study, lettuces were exposed to pristine TiO2-NPs and aged paint leachate containing TiO2-NPs and microparticles (TiO2-MPs). Internalization and in situ speciation of Ti were investigated by a combination of microscopic and spectroscopic techniques. Not only TiO2-NPs pristine and from aged paints, but also TiO2-MPs were internalized in lettuce leaves, and observed in all types of tissues. No change in speciation was noticed, but an organic coating of TiO2-NPs is likely. Phytotoxicity markers were tested for plants exposed to pristine TiO2-NPs. No acute phytotoxicity was observed; variations were only observed in glutathione and phytochelatin levels but remained low as compared to typical values. These results obtained on the foliar uptake mechanisms of nano- and microparticles are important in the perspective of risk assessment of atmospheric contaminations.

  1. The Spectrophotometric Features of Lunar Mare Regions with Higher Content of TIO2

    NASA Astrophysics Data System (ADS)

    Busarev, V. V.

    1988-03-01

    The author investigates spectrophotometrically 8 lunar mare regions with higher content of TiO2. The spectral features attributed to TiO2 and ilmenite in the reflectance spectra of these regions are described.

  2. TiO2 anode materials for lithium-ion batteries with different morphology and additives

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Ng, Yip Hang; Leung, Yu Hang; Liu, Fangzhou; Djurišic, Aleksandra B.; Xie, Mao Hai; Chan, Wai Kin

    2014-03-01

    Electrochemical performances of different TiO2 nanostructures, TiO2/CNT composite and TiO2 with titanium isopropoxide (TTIP) treatment anode were investigated. For different TiO2 nanostructures, we investigated vertically aligned TiO2 nanotubes on Ti foil and TiO2 nanotube-powders fabricated by rapid breakdown anodization technique. The morphology of the prepared samples was characterized by scanning probe microscopy (SEM). The electrochemical lithium storage abilities were studied by galvanostatic method. In addition, carbon nanotubes (CNT) additives and solution treatment process of TiO2 anode were investigated, and the results show that the additives and treatment could enhance the cycling performance of the TiO2 anode on lithium ion batteries.

  3. Robust superamphiphobic film from electrospun TiO2 nanostructures.

    PubMed

    Ganesh, V Anand; Dinachali, Saman Safari; Nair, A Sreekumaran; Ramakrishna, Seeram

    2013-03-13

    Rice-shaped TiO2 nanostructures are fabricated by electrospinning for creating a robust superamphiphobic coating on glass substrates. The as-fabricated TiO2 nanostructures (sintered at 500 °C) are superhydrophilic in nature which upon silanization turn into superamphiphobic surface with surface contact angle (SCA) values achieved using water (surface tension, γ = 72.1 mN/m) and hexadecane (surface tension, γ = 27.5 mN/m) being 166° and 138.5°, respectively. The contact angle hysteresis for the droplet of water and hexadecane are measured to be 2 and 12°, respectively. Thus, we have successfully fabricated superior self-cleaning coatings that possess exceptional superamphiphobic property by employing a simple, cost-effective, and scalable technique called electrospinning. Furthermore, the coating showed good mechanical and thermal stability with strong adherence to glass surface, thus revealing the potential for real applications.

  4. Electrokinetic behaviour of porous TiO2-coated implants.

    PubMed

    Lorenzetti, Martina; Luxbacher, Thomas; Kobe, Spomenka; Novak, Saša

    2015-06-01

    It is known that the "race for the surface" determining the in vivo response is strictly connected to the physico-chemical properties of the material, especially at its surface. Accordingly, the study of surface roughness, charge and wettability is fundamental to predict the bio-response to the implant. In this work, streaming potential was chosen as a reliable method to quantify the solid surface charge of hydrothermally treated (HT) TiO2-anatase nano-crystalline coatings, grown on titanium substrates. The influence of metal and ionic conductance on the zeta potential values was taken into account, allowing for the correlation of the surface charge with the coating porosity, the semiconductor character of the TiO2 nano-crystals and the metallic nature of the bulk titanium.

  5. Photocatalytic antibacterial performance of TiO2 and Ag-doped TiO2 against S. aureus. P. aeruginosa and E. coli.

    PubMed

    Gupta, Kiran; Singh, R P; Pandey, Ashutosh; Pandey, Anjana

    2013-01-01

    This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol-gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV-vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron-hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

  6. Spectroscopic investigation of PVA-TIO2 membranes gamma irradiated

    NASA Astrophysics Data System (ADS)

    Todica, Mihai; Udrescu, Luciana; Damian, Grigore; Astilean, Simion

    2013-07-01

    The modifications of the PVA-TiO2 membranes exposed to gamma radiations were investigated by ESR and XRD methods. The ESR spectra show the appearance of a strong signal associated with the breaking of the polymeric chain and the appearance of the unpaired electrons. The mechanism is influenced by the concentration of TiO2. The modification of local order of the polymeric chains after irradiation is confirmed by XRD method.

  7. Tunable polaronic conduction in anatase TiO2.

    PubMed

    Moser, S; Moreschini, L; Jaćimović, J; Barišić, O S; Berger, H; Magrez, A; Chang, Y J; Kim, K S; Bostwick, A; Rotenberg, E; Forró, L; Grioni, M

    2013-05-10

    Oxygen vacancies created in anatase TiO(2) by UV photons (80-130 eV) provide an effective electron-doping mechanism and induce a hitherto unobserved dispersive metallic state. Angle resolved photoemission reveals that the quasiparticles are large polarons. These results indicate that anatase can be tuned from an insulator to a polaron gas to a weakly correlated metal as a function of doping and clarify the nature of conductivity in this material. PMID:23705725

  8. Tunable Polaronic Conduction in Anatase TiO2

    NASA Astrophysics Data System (ADS)

    Moser, S.; Moreschini, L.; Jaćimović, J.; Barišić, O. S.; Berger, H.; Magrez, A.; Chang, Y. J.; Kim, K. S.; Bostwick, A.; Rotenberg, E.; Forró, L.; Grioni, M.

    2013-05-01

    Oxygen vacancies created in anatase TiO2 by UV photons (80-130 eV) provide an effective electron-doping mechanism and induce a hitherto unobserved dispersive metallic state. Angle resolved photoemission reveals that the quasiparticles are large polarons. These results indicate that anatase can be tuned from an insulator to a polaron gas to a weakly correlated metal as a function of doping and clarify the nature of conductivity in this material.

  9. Synthesis of TiO2 and TiO2-Pt and their application in photocatalytic degradation of humic acid.

    PubMed

    Chen, Wenzhao; Ran, Xianqiang; Jiang, Xu; Min, Hongyang; Li, Dandan; Zou, Liyin; Fan, Jianwei; Li, Guangming

    2014-01-01

    The deposit of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this study, TiO2 nanoparticles were prepared using a sol-gel route followed by heat treatment at elevated temperatures (573 K, 773 K, and 973 K). TiO2-Pt catalyst (1 wt%) was prepared by depositing Pt on the surface of the prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were used as heterogeneous catalysts to remove humic acid with UV-light (120 W) illumination. TiO2 prepared at low temperature with smaller particle size and larger specific surface area had stronger activity on humic acid degradation. Deposit of Pt would favor separation of photogenerated charges and enhance the photocatalyst activity, but its coating of the active site also inhibited degradation of humic acid. The addition of H202 enhanced degradation of humic acid for more active oxygen produced. Low pH (pH = 4) was helpful to adsorb humic acid on the surface of TiO2 and, correspondingly, enhance degradation of humic acid (44.4%).

  10. TiO2 nanowire and TiO2 nanowire doped Ag-PVP nanocomposite for antimicrobial and self-cleaning cotton textile.

    PubMed

    Hebeish, A A; Abdelhady, M M; Youssef, A M

    2013-01-16

    The TiO(2) nanowire (TiO(2) Nw) was successfully prepared via hydrothermal method through TiO(2) nanoparticle (TiO(2) Np). TiO(2) Np doped silver and TiO(2) Nw doped silver were prepared via photo-reducing Ag(+) ions to Ag metal on the TiO(2) Np or TiO(2) Nw surfaces. The prepared nanomaterials were evaluated using X-ray (XRD) diffraction pattern, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Bleached untreated cotton fabric and PVP treated cotton fabrics were coated with the synthesized nanomaterials using pad-dry-cure method. Photocatalytic activity of untreated and coated cotton fabrics with TiO(2) nanomaterials was investigated through the fabric self cleaning of MB dye stains. Also, the PVP finished cotton fabric modified by nanomaterials demonstrated antimicrobial activity against Gram positive bacteria, Gram negative bacteria and fungi. The mechanical properties of coated cotton fabric (tear strength, surface roughness, tensile strength and elongation at break) were examined.

  11. TiO2-polymer composites for biomedical applications.

    PubMed

    Peña, J; Vallet-Regí, M; San Román, J

    1997-04-01

    Composite hydrogels of poly(acrylic acid) (PAA) and poly-(methyl metacrylate) (PMMA) reinforced with a bioceramic, TiO2, have been prepared by reactive moulding from a mixture of the bioceramic with PMMA beads and acrylic acid. Cylindrical specimens with various TiO2-polymer compositions, but a constant 3:1 PAA/PMMA ratio were obtained, and their corresponding swelling behavior was followed at pH = 7.0 and pH = 8.0 in buffered solution at 37 degrees C. The composition and structure of the composites prepared was studied by thermogravimetry, 1H-NMR spectroscopy and scanning electron microscopy. The composites prepared present a considerable consistency, even in hydrated media, since their swelling behavior is rather sensitive to the pH of the media. Specific polar interactions of the carboxylic groups of the hydrophilic polymer component PAA with the surface of TiO2 particles, modulate the behavior of the composites against the hydration processes at different pH.

  12. Photocatalytic cleavage of single TiO2/DNA nanoconjugates.

    PubMed

    Tachikawa, Takashi; Asanoi, Yoshiaki; Kawai, Kiyohiko; Tojo, Sachiko; Sugimoto, Akira; Fujitsuka, Mamoru; Majima, Tetsuro

    2008-01-01

    TiO(2)/DNA nanoconjugates were successfully fabricated by using the catechol moiety as a binding functional group, which was confirmed by steady-state absorption and fluorescence spectroscopies. Upon UV irradiation, the photocatalytic cleavage of the TiO(2)/DNA nanoconjugates was observed at the single-molecule level by using wide-field fluorescence microscopy. The decrease in the number of conjugates, which was estimated from the luminescent spots due to semiconductor quantum dots modified at the DNA strand, was significantly inhibited by a single A/C mismatch in the DNA sequences. This result strongly suggests that the migration of holes, which are injected from the photoexcited TiO(2) into the DNA, through the DNA bases plays an important role in the photocatalytic cleavage of the conjugates. The influences of the photogenerated reactive oxygen species (ROS) on the cleavage efficiency were also examined. According to the experimental results, it was concluded that oxidation of the catechol moiety and/or the DNA damage are key reactions in this process.

  13. Raman spectroscopy of ball-milled TiO 2

    NASA Astrophysics Data System (ADS)

    Gajović, A.; Stubičar, M.; Ivanda, M.; Furić, K.

    2001-05-01

    Raman spectroscopy was applied to study structural and dimensional changes during high-energy ball milling of TiO 2 anatase. Milling was performed for up to 10 h using two different sets of grinding tools (wolfram carbide (WC) and agate). The diminution of the TiO 2 particle to nanometric size was monitoring by low-frequency Raman spectroscopy. The nanometric sizes were confirmed by transmission electron microscopy (TEM). After short milling time by WC the bands of high-pressure TiO 2 II phase (α-PbO 2 structure) were detected in Raman spectrum. Prolonged milling time was needed for transformation to rutil. When milling was performed by agate, the time necessary for both phase transitions was longer, presumably because of lower ball-to-powder weight ratio. The low-frequency Raman band of the prolonged milled samples was broad, which suggests the wide dispersion in nano-particle dimensions. The position of the low-frequency band in longer-milled samples indicated dimensions smaller than 20 nm, since the diameter of the particle is inversely proportional to the low-frequency mode of the spherical particles. These results were in agreement with the TEM results.

  14. Transparent Nano-Crystalline TiO2 films

    NASA Astrophysics Data System (ADS)

    Sakthivel, K.; Venkatachalam, T.; Renugadevi, R.

    2011-10-01

    Thin films of TiO2 have been deposited on well cleaned glass substrates by Sol-Gel dip-drive coating technique. The films have been prepared at three different pH values (3, 5, and 9) of Sol and annealed in muffle furnace at three distinct temperatures (350 °C, 450 °C, and 550 °C) for one hour and are allowed to cool to room temperature. The films were characterized by XRD, EDAX, SEM and UV-Vis Spectrophotometer. The as deposited films were found to be amorphous in nature. The annealed films exhibit anatase in crystalline structure. The EDAX results have shown that all the films are maintained with TiO2 in composition. The XRD results reveal that they are nano-crystalline in nature and the crystalline nature increases with annealing temperature and pH of the Sol. The transmittance and absorbance spectra have shown that the films are transparent and band gap of the films are of the order of 3 eV. The ab initio studies of TiO2 (using GGA) was performed with Vienna ab initio Simulation package and the band structure and effective masses of the electrons and holes were determined.

  15. Optofluidic microreactors with TiO2-coated fiberglass.

    PubMed

    Li, Lin; Chen, Rong; Zhu, Xun; Wang, Hong; Wang, Yongzhong; Liao, Qiang; Wang, Dongye

    2013-12-11

    Optofluidic microreactors are promising prospects for photocatalytic reactions. However, because the flow type in conventional designs is typically laminar, the mass transport mainly relies on diffusion, and thus the rate of mass transport is limited. Accordingly, poor mass transport reduces the photocatalytic reaction rate. To alleviate the limitation of mass transport, in this work, we proposed a novel optofluidic microreactor with TiO2-coated fiberglasses immersed in the microreaction chamber. Such a design enables enhanced mass transport by shortening the transport length and inducing the perturbation to liquid flow so as to improve the performance. We demonstrated the feasibility of the optofluidic microreactor with the TiO2-coated fiberglass by the photocatalytic water treatment of methylene blue under UV irradiation. Results showed that the proposed optofluidic microreactor yielded much higher degradation efficiency than did the conventional optofluidic microreactor as a result of enhanced mass transport. The microreactor with the TiO2-coated fiberglass showed a 2-3-fold improvement in the reaction rate constant as opposed to conventional ones. The maximal increment of the degradation efficiency can reach more than 40%. PMID:24262010

  16. BIOLOGICAL RESPONSE TO NANO-SCALE TIO2: ROLE OF PARTICLE DOSE, SHAPE AND RETENTION

    PubMed Central

    Silva, Rona M.; TeeSy, Christel; Franzi, Lisa; Weir, Alex; Westerhoff, Paul; Evans, James E.; Pinkerton, Kent E.

    2015-01-01

    TiO2 is one of the most widely used nanomaterials, valued for its highly refractive, photocatalytic and pigmenting properties. TiO2 is also classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen. The objectives of this study were to establish a lowest observed effect level (LOEL) for nano-scale TiO2, determine TiO2 uptake in the lungs, and estimate toxicity based on physico-chemical properties and retention in the lungs. In vivo lung toxicity of nano-scale TiO2 using varying forms of well-characterized, highly-dispersed TiO2 was assessed. Anatase/rutile P25 spheres (TiO2-P25), pure anatase spheres (TiO2-A), and anatase nanobelts (TiO2-NB) were tested. To determine the effects of dose and particle characteristics, male Sprague-Dawley rats were given TiO2 (0, 20, 70, or 200 µg) via intratracheal instillation. Broncho-alveolar lavage fluid (BALF) and lung tissue were obtained for analysis 1 and 7 days post exposure. Despite abundant TiO2 inclusions in all exposed animals, only TiO2-NB elicited any significant degree of inflammation seen in BALF at the 1-day time-point. This inflammation resolved by 7 days; although, TiO2 particles had not cleared from alveolar macrophages recovered from the lung. Histological examination showed TiO2-NB caused cellular changes at day 1 which were still evident at day 7. We conclude TiO2-NB is the most inflammatory with a lowest observable effect level of 200 µg at 1 day post instillation. PMID:24156719

  17. Photocatalytic degradation of rhodamine B by anchored TiO2 nanowires.

    PubMed

    Wang, Chih-Chieh; Yu, Chung-Yi; Kei, Chi-Chung; Perng, Tsong-Pyng

    2011-01-01

    Rutile TiO2 nanowires anchored on silica were fabricated by annealing TiO2 nanoparticles dispersed on silicon or quartz substrate by means of a polystyrene nanosphere monolayer template at 1000 degrees C for 1 h without any catalyst. The diameter and length of the nanowires were 30-80 nm and 1-3 microm, respectively. The growth direction of the nanowires is [112]. The photocatalytic activities of TiO2 nanoparticles and anchored nanowires were evaluated. TiO2 nanowires had higher photocatalytic activity for rhodamine B than TiO2 nanoparticles.

  18. Photocatalytic Water-Splitting Characteristic of Electric Reduced Black TiO2 Nanorods

    NASA Astrophysics Data System (ADS)

    Yun, Jong-Won; Ryu, Ki Yeon; Kim, Sunho; Jang, Se-Jung; Kim, Yong Soo

    In various reduction methods of TiO2, the electric reduction could apply to anodized TiO2 nanotube. However, it is not suitable to reduce TiO2 nanorods(NRs) grown on fluorine doped tin oxide (FTO) substrate using hydrothermal method, because those are easily peeled off due to lattice mismatching between FTO and TiO2 NRs. In this talk, we will demonstrate electric reduced-black TiO2 NRs with strong adhesion on FTO substrate for an effective visible photocatalyst. To fabricate the reduced-black TiO2 NRs, we firstly deposited TiO2 seed layer on FTO glass using RF-sputtering for mitigating the exfoliation, then grow TiO2 NRs with hydrothermal method. Finally, TiO2 NRs were reduced with electric bias. The final reduced-black TiO2 NRs exhibit a higher photocurrent density, 0.9 mA/cm2 in comparison with pure-TiO2 NRs. This result indicates that our reduced-black TiO2 NRs has lower bandgap with modified valance band position and enhance the surface reactivity with oxygen defect generation. This research was supported by Priority Research Centers Program (2009-0093818), the Basic Science Research Program (2015-019609) and Basic Research Lab Program (2014-071686) through National Research Foundation of Korea (NRF) funded by the Korean government.

  19. Reaction pathways of dimethyl phthalate degradation in TiO2-UV-O2 and TiO2-UV-Fe(VI) systems.

    PubMed

    Yuan, Bao-ling; Li, Xiang-zhong; Graham, Nigel

    2008-05-01

    The photocatalytic degradation of dimethyl phthalate (DMP) in aqueous TiO2 suspension under UV illumination has been investigated using oxygen (O2) and ferrate (Fe(VI)) as electron acceptors. The experiments demonstrated that Fe(VI) was a more effective electron acceptor than O2 for scavenging the conduction band electrons from the surface of the catalyst. Some major intermediate products from DMP degradation were identified by HPLC and GC/MS analyses. The analytical results identified dimethyl 3-hydroxyphthalate and dimethyl 2-hydroxyphthalate as the two main intermediate products from the DMP degradation in the TiO2-UV-O2 system, while in contrast phthalic acid was found to be the main intermediate product in the TiO2-UV-Fe(VI) system. These findings indicate that DMP degradation in the TiO2-UV-O2 and TiO2-UV-Fe(VI) systems followed different reaction pathways. An electron spin resonance analysis confirmed that hydroxyl radicals existed in the TiO2-UV-O2 reaction system and an unknown radical species (most likely an iron-oxo species) is suspected to exist in the TiO2-UV-Fe(VI) reaction system. Two pathway schemes of DMP degradation in the TiO2-UV-O2 and TiO2-UV-Fe(VI) reaction systems are proposed. It is believed that the radicals formed in the TiO2-UV-O2 reaction system preferably attack the aromatic ring of the DMP, while in contrast the radicals formed in the TiO2-UV-Fe(VI) reaction systems attack the alkyl chain of DMP.

  20. Enhanced photoelectrochemical and photocatalytic activity of WO3-surface modified TiO2 thin film.

    PubMed

    Qamar, Mohammad; Drmosh, Qasem; Ahmed, Muhammad I; Qamaruddin, Muhammad; Yamani, Zain H

    2015-01-01

    Development of nanostructured photocatalysts for harnessing solar energy in energy-efficient and environmentally benign way remains an important area of research. Pure and WO3-surface modified thin films of TiO2 were prepared by magnetron sputtering on indium tin oxide glass, and photoelectrochemical and photocatalytic activities of these films were studied. TiO2 particles were <50 nm, while deposited WO3 particles were <20 nm in size. An enhancement in the photocurrent was observed when the TiO2 surface was modified WO3 nanoparticles. Effect of potential, WO3 amount, and radiations of different wavelengths on the photoelectrochemical activity of TiO2 electrodes was investigated. Photocatalytic activity of TiO2 and WO3-modified TiO2 for the decolorization of methyl orange was tested. Graphical abstractWO3-surface modified TiO2 film showing better photocatalytic and photoelectrocatalytic activity. PMID:25852351

  1. Study of TiO2 nanotubes as an implant application

    NASA Astrophysics Data System (ADS)

    Hazan, Roshasnorlyza; Sreekantan, Srimala; Mydin, Rabiatul Basria S. M. N.; Abdullah, Yusof; Mat, Ishak

    2016-01-01

    Vertically aligned TiO2 nanotubes have become the primary candidates for implant materials that can provide direct control of cell behaviors. In this work, 65 nm inner diameters of TiO2 nanotubes were successfully prepared by anodization method. The interaction of bone marrow stromal cells (BMSC) in term of cell adhesion and cell morphology on bare titanium and TiO2 nanotubes is reported. Field emission scanning electron microscopy (FESEM) analysis proved interaction of BMSC on TiO2 nanotubes structure was better than flat titanium (Ti) surface. Also, significant cell adhesion on TiO2 nanotubes surface during in vitro study revealed that BMSC prone to attach on TiO2 nanotubes. From the result, it can be conclude that TiO2 nanotubes are biocompatible to biological environment and become a new generation for advanced implant materials.

  2. Biodistribution and Clearance of TiO2 Nanoparticles in Rats after Intravenous Injection

    PubMed Central

    Elgrabli, Dan; Beaudouin, Remy; Jbilou, Nawel; Floriani, Magali; Pery, Alexandre; Rogerieux, Françoise; Lacroix, Ghislaine

    2015-01-01

    Titanium dioxide (TiO2) nanoparticles are used in many applications. Due to their small size, easy body penetration and toxicological adverse effects have been suspected. Numerous studies have tried to characterize TiO2 translocation after oral, dermal or respiratory exposure. In this study, we focused on TiO2 nanoparticle biodistribution, clearance and toxicological effects after intravenous injection, considering TiO2 translocation in the blood occurs. Using ICP-OES, transmission electron microscopy, and histological methods, we found TiO2 accumulation in liver, lungs and spleen. We estimated TiO2 nanoparticles’ half life in the body to about 10 days. Clinical biomarkers were also quantified for 56 days to identify potential toxicological impact on lungs, blood, liver, spleen and kidneys. Results showed absence of toxicological effects after TiO2 intravenous injection at concentrations of 7.7 to 9.4 mg/kg. PMID:25909957

  3. Bimodal TiO2 Contents of Mare Basalts at Apollo and Luna Sites and Implications for TiO2 Derived from Clementine Spectral Reflectance

    NASA Technical Reports Server (NTRS)

    Gillis, J. J.; Jolliff, B. L.

    2001-01-01

    A revised algorithm to estimate Ti contents of mare regions centered on Apollo and Luna sites shows a bimodal distribution, consistent with mare-basalt sample data. A global TiO2 map shows abundant intermediate TiO2 basalts in western Procellarum. Additional information is contained in the original extended abstract.

  4. Facile Scalable Synthesis of TiO2/Carbon Nanohybrids with Ultrasmall TiO2 Nanoparticles Homogeneously Embedded in Carbon Matrix.

    PubMed

    Wang, Xiaoyan; Meng, Jian-Qiang; Wang, Meimei; Xiao, Ying; Liu, Rui; Xia, Yonggao; Yao, Yuan; Metwalli, Ezzeldin; Zhang, Qian; Qiu, Bao; Liu, Zhaoping; Pan, Jing; Sun, Ling-Dong; Yan, Chun-Hua; Müller-Buschbaum, Peter; Cheng, Ya-Jun

    2015-11-01

    A facile scalable synthesis of TiO2/C nanohybrids inspired by polymeric dental restorative materials has been developed, which creates ultrasmall TiO2 nanoparticles homogeneously embedded in the carbon matrix. The average size of the nanoparticles is tuned between about 1 and 5 nm with the carbon content systematically increased from 0% to 65%. Imaging analysis and a scattering technique have been applied to investigate the morphology of the TiO2 nanoparticles. The composition, nature of carbon matrix, crystallinity, and tap density of the TiO2/C nanohybrids have been studied. The application of the TiO2/C nanohybrids as lithium-ion battery anode is demonstrated. Unusual discharge/charge profiles have been exhibited, where characteristic discharge/charge plateaus of crystalline TiO2 are significantly diminished. The tap density, cyclic capacities, and rate performance at high current densities (10 C, 20 C) of the TiO2/C nanohybrid anodes have been effectively improved compared to the bare carbon anode and the TiO2/C nanohybrids with larger particle size. PMID:26465800

  5. Visible light catalysis of rhodamine B using nanostructured Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films.

    PubMed

    Mahadik, M A; Shinde, S S; Mohite, V S; Kumbhar, S S; Moholkar, A V; Rajpure, K Y; Ganesan, V; Nayak, J; Barman, S R; Bhosale, C H

    2014-04-01

    The Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) composite films are deposited using spray pyrolysis method onto glass and FTO coated substrates. The structural, morphological, optical and photocatalytic properties of Fe(2)O(3), TiO(2) and TiO(2)/Fe(2)O(3) thin films are studied. XRD analysis confirms that films are polycrystalline with rhombohedral and tetragonal crystal structures for Fe2O3 and TiO(2) respectively. The photocatalytic activity was tested for the degradation of Rhrodamine B (Rh B) in aqueous medium. The rate constant (-k) was evaluated as a function of the initial concentration of species. Substantial reduction in concentrations of organic species was observed from COD and TOC analysis. Photocatalytic degradation effect is relatively higher in case of the TiO(2)/Fe(2)O(3) than TiO(2) and Fe(2)O(3) thin film photoelectrodes in the degradation of Rh B and 98% removal efficiency of Rh B is obtained after 20min. The photocatalytic experimental results indicate that TiO(2)/α-Fe(2)O(3) photoelectrode is promising material for removing of water pollutants.

  6. Positive role of incorporating P-25 TiO2 to mesoporous-assembled TiO2 thin films for improving photocatalytic dye degradation efficiency.

    PubMed

    Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2014-09-15

    In this work, a simple and effective strategy to improve the photocatalytic dye degradation efficiency of the mesoporous-assembled TiO2 nanoparticle thin films by incorporating small contents of commercial P-25 TiO2 during the thin film preparation was developed. The mesoporous-assembled TiO2 nanoparticles were synthesized by a sol-gel method with the aid of a mesopore-directing surfactant, followed by homogeneously mixing with P-25 TiO2 prior to the thin film coating on glass substrate. The mesoporous-assembled TiO2 film with 5 wt.% P-25 TiO2 incorporation and calcined at 400°C provided an improved photocatalytic Acid Black (AB) dye degradation efficiency. The increase in number of coated layers to the optimum four layers of the aforementioned film was found to further improve the degradation efficiency. The recyclability test of this 5 wt.% P-25 TiO2-incorporated mesoporous-assembled TiO2 film with four coated layers revealed that it can be reused for multiple cycles without a requirement of post-treatment while the degradation efficiency was retained.

  7. Effect of the rutile content on the photovoltaic performance of the dye-sensitized solar cells composed of mixed-phase TiO2 photoelectrodes.

    PubMed

    Yun, Tae Kwan; Park, Sung Soo; Kim, Duckhyun; Shim, Jae-Hyun; Bae, Jae Young; Huh, Seong; Won, Yong Sun

    2012-01-28

    The effect of the rutile content on the photovoltaic performance of dye-sensitized solar cells (DSSCs) composed of mixed-phase TiO(2) photoelectrode has been investigated. The mixed-phase TiO(2) particles with varied amounts of rutile, relative to anatase phase, are synthesized by an in situ method where the concentration of sulfate ion is used as a phase-controlling parameter in the formation of TiO(2) using TiCl(4) hydrolysis. The surface area (S(BET)) varies from 33 (pure rutile) to 165 (pure anatase) m(2) g(-1). Generally, both the current density (J(sc)) and photo-conversion efficiency (η) decrease as the rutile content increases. The incorporation of rod-shaped rutile particles causes low uptake of dye due to the reduced surface area, as well as slow electron transport in less efficiently-stacked structure. However, maximum J(sc) (14.63 mA cm(-2)) and η (8.69%) appear when relatively low rutile content (16%) is employed. The reported synergistic effect by the efficient interparticle electron transport from rutile to anatase seems to overbalance the decrease of surface area when small amount of rutile particles is incorporated. PMID:22124477

  8. Enhanced Dispersion of TiO2 Nanoparticles in a TiO2/PEDOT:PSS Hybrid Nanocomposite via Plasma-Liquid Interactions

    PubMed Central

    Liu, Yazi; Sun, Dan; Askari, Sadegh; Patel, Jenish; Macias-Montero, Manuel; Mitra, Somak; Zhang, Richao; Lin, Wen-Feng; Mariotti, Davide; Maguire, Paul

    2015-01-01

    A facile method to synthesize a TiO2/PEDOT:PSS hybrid nanocomposite material in aqueous solution through direct current (DC) plasma processing at atmospheric pressure and room temperature has been demonstrated. The dispersion of the TiO2 nanoparticles is enhanced and TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased electrical conductivity was observed for the plasma treated TiO2/PEDOT:PSS nanocomposite. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma treated TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are proposed to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer binding. PMID:26497265

  9. Enhanced Dispersion of TiO2 Nanoparticles in a TiO2/PEDOT:PSS Hybrid Nanocomposite via Plasma-Liquid Interactions

    NASA Astrophysics Data System (ADS)

    Liu, Yazi; Sun, Dan; Askari, Sadegh; Patel, Jenish; Macias-Montero, Manuel; Mitra, Somak; Zhang, Richao; Lin, Wen-Feng; Mariotti, Davide; Maguire, Paul

    2015-10-01

    A facile method to synthesize a TiO2/PEDOT:PSS hybrid nanocomposite material in aqueous solution through direct current (DC) plasma processing at atmospheric pressure and room temperature has been demonstrated. The dispersion of the TiO2 nanoparticles is enhanced and TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased electrical conductivity was observed for the plasma treated TiO2/PEDOT:PSS nanocomposite. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma treated TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are proposed to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer binding.

  10. A computational study of the TiO2 molecule

    NASA Technical Reports Server (NTRS)

    Ramana, M. V.; Phillips, D. H.

    1988-01-01

    A computational investigation of the ground 1A1 and lowest energy B2 states of the titanium dioxide molecule has been carried out. The treatment utilized SCF calculations in an extended basis followed by a CI treatment for each geometry. The ground state geometry agrees well with experiment, while the agreement between the computed vibrational frequency nu1 and the experimental value for a matrix isolated TiO2 is less satisfactory. Population analysis for the ground state indicates less than one excess electron on each oxygen atom. The first excited state has a linear geometry and the singlet and triplet are essentially degenerate.

  11. TIO2 Based Electrorheological Fluid with High Yield Stress

    NASA Astrophysics Data System (ADS)

    Shen, Rong; Wang, Xuezhao; Wen, Weijia; Lu, Kunquan

    We have fabricated several TiO2 based ER fluids with doping and without designed doping, which exhibit the high yield stress up to more than 100kPa. The titanium oxide nanoparticles were synthesized by using wet chemical method. The ER effect of those materials is dominated by the special additives, such as amide or its ramification, as well as the remained molecules or ions in the sample preparation. It is found that the yield stress is also strongly dependent on the viscosity of the oil. The prepared ER fluids possess other attractive characters, for instance the current density is low and against sedimentation.

  12. Origin of unexpected magnetism in Cu-doped TIO2

    NASA Astrophysics Data System (ADS)

    Li, Q. K.; Wang, B.; Woo, C. H.; Wang, H.; Zhu, Z. Y.; Wang, R.

    2008-01-01

    Cu-doped TiO2 has recently been found to exhibit unexpected room temperature ferromagnetism. In the present work, possible defect structures and the associated magnetism are calculated within the generalized gradient approximation using the projector augmented wave method (PAW). In particular, structures of the vacancy-Cu impurity complex are studied. Our results show that the magnetism is caused by: 1) the hybridization of p-d orbitals between the Cu and O ions, and 2) the spin polarization of the 3d orbital of Cu and of the 2p orbital of O ions.

  13. Improved photoelectrical performance of graphene supported highly crystallized anatase TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Sun, Qiong; Zhao, Mei; Li, Yang; Liu, Qiuhong; Dong, Lifeng

    2015-08-01

    In this study, titanium oxysulfate (TiOSO4) and graphene were used as titanium source and supporter, respectively, to synthesize anatase TiO2-graphene (TiO2-G) composite. Crystal structure, morphology, and composition of TiO2-G were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope, and thermogravimetric analysis. Both TiO2-G and blank TiO2 powders exhibit spindle-shaped structure with the long axis along [001]. Compared to unsupported TiO2, TiO2 nanoparticles uniformly formed on graphene surface. When fabricated into dye-sensitized solar cells, photoelectrical conversion efficiency of TiO2-G (2.3 %) was much higher than that of blank TiO2 (0.89 %) prepared at the same conditions. Moreover, high sintering temperature enhanced photoelectrical performance of the composite. When the temperature was increased from 450 to 600 °C, the efficiency was improved from 1.5 to 2.6 %. The findings above demonstrate that TiO2-G has great potential for applications in dye-sensitized solar cells.

  14. Physiological effect of anatase TiO2 nanoparticles on Lemna minor.

    PubMed

    Song, Guanling; Gao, Yuan; Wu, Hao; Hou, Wenhua; Zhang, Chunyang; Ma, Huiquan

    2012-09-01

    Manufactured metal oxide nanoparticles (NPs) are being used on a large scale, and these particles will inevitably reach a body of water through wastewater and urban runoff. The ecotoxicological study of these NPs on hydrophyte is limited at present. Lemna minor was exposed to media with different concentrations of titanium dioxide (TiO(2)) NPs or bulk TiO(2) for 7 d. The changes in plant growth, chlorophyll, antioxidant defense enzymes (peroxidase [POD], catalase [CAT], and superoxide dismutase [SOD] activities), and malondialdehyde (MDA) content were measured in the present study. The particle size of TiO(2) NPs and the zeta potential of TiO(2) NPs and of bulk TiO(2) in the culture media were also analyzed to complementally study the toxicity of these materials on duckweed. The results showed that the effect of TiO(2) NPs on plant growth was more obvious than bulk TiO(2.) Titanium dioxide NPs stimulated plant growth in low concentrations, but inhibited plant growth at high concentrations. The POD, SOD, and CAT activity of Lemna minor increased when TiO(2) NP concentration was lower than 200 mg/L to eliminate accumulated reactive oxygen species in plant cells. The SOD activity decreased when the TiO(2) NP concentration was higher than 200 mg/L, and the plant cell membrane encountered serious damage from 500 mg/L TiO(2) NP concentration in the culture media.

  15. TiO2 coated microfluidic devices for recoverable hydrophilic and hydrophobic patterns

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Hyung; Kim, Sang Kyung; Park, Hyung-Ho; Kim, Tae Song

    2015-03-01

    We report a simple method for modifying the surfaces of plastic microfluidic devices through dynamic coating process with a nano-colloidal TiO2 sol. The surface of the thermoplastic, cyclic olefin copolymer (COC) was coated with the TiO2 film, that displayed an effective photocatalytic property. The hydrophilic surface is obtained in the TiO2-coated zone of a microfluidic channel, and TiO2 coated surface degradation can be reversed easily by UV irradiation. The present work shows a photocatalytic activity concerning the effect of TiO2 coating density, which is controlled by the number of coating cycles. The hydrophilized surface was characterized by the contact angle of water and the TiO2 coated COC surface reduced the water contact angle from 85° to less than 10° upon UV irradiation. The photocatalytic effect of the layer that was coated five times with TiO2 was excellent, and the super-hydrophilicity of the TiO2 surface could be promptly recovered after 10 months of storage at atmospheric conditions. The COC microfluidic devices, in which TiO2 has been freshly deposited and aged for 10 months, were capable of generating water-in oil-in water (W/O/W) double emulsions easily and uniformly by simple control of the flow rates for demonstration of excellent hydrophilic patterning and recovery of the TiO2 coated in the microchannels.

  16. The interplay of peptide sequence and local structure in TiO2 biomineralization.

    PubMed

    Choi, Noori; Tan, Lihan; Jang, Ji-ryang; Um, Yu Mi; Yoo, Pil J; Choe, Woo-Seok

    2012-10-01

    Using cyclic constrained TiO(2) binding peptides STB1 (CHKKPSKSC), RSTB1 (CHRRPSRSC) and linear peptide LSTB1 (AHKKPSKSA), it was shown that while affinity of the peptide to TiO(2) is essential to enable TiO(2) biomineralization, other factors such as biomineralization kinetics and peptide local structure need to be considered to predict biomineralization efficacy. Cyclic and linear TiO(2) binding peptides show significantly different biomineralization activities. Cyclic STB1 and RSTB1 could induce TiO(2) precipitation in the presence of titanium(IV)-bis-ammonium-lactato-dihydroxide (TiBALDH) precursor in water or tris buffer at pH 8. In contrast, linear LSTB1 was unable to mineralize TiO(2) under the same experimental conditions despite its high affinity to TiO(2) comparable with STB1 and/or RSTB1. LSTB1 being a flexible molecule could not render the stable condensation of TiBALDH precursor to form TiO(2) particles. However, in the presence of phosphate buffer ions, the structure of LSTB1 is stabilized, leading to efficient condensation of TiBALDH and TiO(2) particle formation. This study demonstrates that peptide-mediated TiO(2) mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of mineralizing aider such as phosphate ions.

  17. Activity of Laccase Immobilized on TiO2-Montmorillonite Complexes

    PubMed Central

    Wang, Qingqing; Peng, Lin; Li, Guohui; Zhang, Ping; Li, Dawei; Huang, Fenglin; Wei, Qufu

    2013-01-01

    The TiO2-montmorillonite (TiO2-MMT) complex was prepared by blending TiO2 sol and MMT with certain ratio, and its properties as an enzyme immobilization support were investigated. The pristine MMT and TiO2-MMT calcined at 800 °C (TiO2-MMT800) were used for comparison to better understand the immobilization mechanism. The structures of the pristine MMT, TiO2-MMT, and TiO2-MMT800 were examined by HR-TEM, XRD and BET. SEM was employed to study different morphologies before and after laccase immobilization. Activity and kinetic parameters of the immobilized laccase were also determined. It was found that the TiO2 nanoparticles were successfully introduced into the MMT layer structure, and this intercalation enlarged the “d value” of two adjacent MMT layers and increased the surface area, while the calcination process led to a complete collapse of the MMT layers. SEM results showed that the clays were well coated with adsorbed enzymes. The study of laccase activity revealed that the optimum pH and temperature were pH = 3 and 60 °C, respectively. In addition, the storage stability for the immobilized laccase was satisfactory. The kinetic properties indicated that laccase immobilized on TiO2-MMT complexes had a good affinity to the substrate. It has been proved that TiO2-MMT complex is a good candidate for enzyme immobilization. PMID:23771020

  18. A facile method for the structure control of TiO2 particles at low temperature

    NASA Astrophysics Data System (ADS)

    Li, Zhaoqing; Zhu, Yun; Wang, Lianwen; Wang, Jiatai; Guo, Qian; Li, Jiangong

    2015-11-01

    Crystalline and amorphous TiO2 particles have important potential applications in photocatalysis, structural ceramics, solar batteries and nanoglasses. Hence controlling the structure of TiO2 particles is of practical importance. Crystalline TiO2 particles are usually prepared by calcination of their amorphous precursor. Here a facile method was developed to control the structure of TiO2 particles at a low temperature. TiO2 particles were prepared by sol-gel method; and it was found that during the washing process, the TiO2 particles washed with water are crystalline whereas the TiO2 particles washed with ethanol are amorphous. Further analyses indicate that ethanol washing may introduce an organic cover layer on the TiO2 particles which hinders the crystallization of amorphous TiO2 particles. Therefore, the structure of TiO2 particles, amorphous or crystalline (anatase), can be controlled just by changing the washing medium, water or ethanol. This method seems a common method for controlling the (amorphous or crystalline) structure of metal oxides and hydroxides and was verified in the preparation of ZrO2, FeO(OH), and Al(OH)3 particles.

  19. Immobilization of TiO2 nanofibers on reduced graphene sheets: Novel strategy in electrospinning.

    PubMed

    Pant, Hem Raj; Adhikari, Surya Prasad; Pant, Bishweshwar; Joshi, Mahesh K; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2015-11-01

    A simple and efficient approach is developed to immobilize TiO2 nanofibers onto reduced graphene oxide (RGO) sheets. Here, TiO2 nanofiber-intercalated RGO sheets are readily produced by two-step procedure involving the use of electrospinning process to fabricate TiO2 precursor containing polymeric fibers on the surface of GO sheets, followed by simultaneous TiO2 nanofibers formation and GO reduction by calcinations. GO sheets deposited on the collector during electrospinning/electrospray can act as substrate on to which TiO2 precursor containing polymer nanofibers can be deposited which give TiO2 NFs doped RGO sheets on calcinations. Formation of corrugated structure cavities of graphene sheets decorated with TiO2 nanofibers on their surface demonstrates that our method constitutes an alternative top-down strategy toward fabricating verities of nanofiber-decorated graphene sheets. It was found that the synthesized TiO2/RGO composite revealed a remarkable increased in photocatalytic activity compared to pristine TiO2 nanofibers. Therefore, engineering of TiO2 nanofiber-intercalated RGO sheets using proposed facile technique can be considered a promising method for catalytic and other applications.

  20. Structural and optical characterization of electrodeposited CdSe in mesoporous anatase TiO2 for regenerative quantum-dot-sensitized solar cells.

    PubMed

    Sauvage, Frédéric; Davoisne, Carine; Philippe, Laetitia; Elias, Jamil

    2012-10-01

    We investigated CdSe-sensitized TiO(2) solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO(2) gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO(2) nanoparticles. This technique has the advantage of providing not only a fast method for sensitization ( < 5 min) but also being easily scalable to the sensitization of large-area panels. XRD together with SAED analysis highlight that the deposit of CdSe is exclusively constituted of the hexagonal polymorph. In addition, hierarchical growth has also been shown, starting from the formation of a TiO(2)-CdSe core-shell structure followed by the growth of an assembly of CdSe nanoparticles resembling cauliflowers. This assembly exhibits at its core a mosaic texture with crystallites of about 3 nm in size, in contrast to a shell composed of well-crystallized single crystals between 5 and 10 nm in size. Preliminary results on the photovoltaic performance of such a nanostructured composite of TiO(2) and CdSe show 0.8% power conversion efficiency under A.M.1.5 G conditions-100 mW cm(-2) in association with a new regenerative redox couple based on cobalt(+III/+II) polypyridil complex (V(oc ) = 485 mV, J(sc ) = 4.26 mA cm (-2), ff=0.37).

  1. Structural and optical characterization of electrodeposited CdSe in mesoporous anatase TiO2 for regenerative quantum-dot-sensitized solar cells.

    PubMed

    Sauvage, Frédéric; Davoisne, Carine; Philippe, Laetitia; Elias, Jamil

    2012-10-01

    We investigated CdSe-sensitized TiO(2) solar cells by means of electrodeposition under galvanostatic control. The electrodeposition of CdSe within the mesoporous film of TiO(2) gives rise to a uniform, thickness controlled, conformal layer of nanostructured CdSe particles intimately wrapping the anatase TiO(2) nanoparticles. This technique has the advantage of providing not only a fast method for sensitization ( < 5 min) but also being easily scalable to the sensitization of large-area panels. XRD together with SAED analysis highlight that the deposit of CdSe is exclusively constituted of the hexagonal polymorph. In addition, hierarchical growth has also been shown, starting from the formation of a TiO(2)-CdSe core-shell structure followed by the growth of an assembly of CdSe nanoparticles resembling cauliflowers. This assembly exhibits at its core a mosaic texture with crystallites of about 3 nm in size, in contrast to a shell composed of well-crystallized single crystals between 5 and 10 nm in size. Preliminary results on the photovoltaic performance of such a nanostructured composite of TiO(2) and CdSe show 0.8% power conversion efficiency under A.M.1.5 G conditions-100 mW cm(-2) in association with a new regenerative redox couple based on cobalt(+III/+II) polypyridil complex (V(oc ) = 485 mV, J(sc ) = 4.26 mA cm (-2), ff=0.37). PMID:22972037

  2. Synthesis and Characterization of TiO2 Nanotubes Sensitized with CdS Quantum Dots Using a One-Step Method

    NASA Astrophysics Data System (ADS)

    Song, Jiahui; Zhang, Xinguo; Zhou, Chunyan; Lan, Yuwei; Pang, Qi; Zhou, Liya

    2015-01-01

    A novel one-step synthesis process was used to assemble CdS quantum dots (QDs) into TiO2 nanotube arrays (TNTAs). The sensitization time of the TiO2 nanotubes can be adjusted by controlling the CdS QD synthesis time. The absorption band of sensitized TNTAs red-shifted and broadened to the visible spectrum. The photoelectric conversion efficiency increased to 0.83%, the open-circuit voltage to 776 mV, and the short-circuit current density ( J SC) to 2.30 mA cm-2 with increased sensitization time. The conversion efficiency with this new sensitization method was five times that of nonsensitized TNTAs, providing novel ideas for study of TNTA solar cells.

  3. Effects of TiO2 coating dosage and operational parameters on a TiO2/Ag photocatalysis system for decolorizing Procion red MX-5B.

    PubMed

    Lin, Yu-Chih; Lee, Ho-Shan

    2010-07-15

    In this study, titanium dioxide (TiO(2)) powder was coated onto the surface of a dendritic silver (Ag) carrier to synthesize TiO(2)/Ag for decolorizing Procion red MX-5B (MX-5B), and related operation factors were also studied. The results showed that even without ultraviolet-A (UVA) irradiation, the Ag carrier from the TiO(2)/Ag catalyst had oxidizing ability, which could effectively degrade MX-5B color, but TiO(2) was ineffective. In addition, TiO(2) from TiO(2)/Ag demonstrated photocatalysis performance when irradiated, and the Ag carrier further showed an electron-scavenging ability to mitigate electron-hole pair recombination, which can improve the photocatalytic efficacy. With the oxidization and electron-scavenging ability of Ag and the photocatalysis ability of TiO(2), TiO(2)/Ag can decolor MX-5B more efficiently than TiO(2). The heavier Ag carrier also improves the solid-liquid separation of nano-TiO(2), making TiO(2)/Ag more suitable for application in slurry systems of photocatalytic water treatment. When the TiO(2)/Ag coating ratio was 50% by weight, there was a sufficient amount of TiO(2) on Ag's surface with a good distribution, and it exhibited a good photocatalysis decolorizing effect. In a study of how operational factors impact the decolorizing of MX-5B in the TiO(2)/Ag photocatalysis system with UVA irradiation (UVA-TiO(2)/Ag), the decolorization efficiency was optimal when the solution was maintained at pH 6.35. The addition of 0.01 M hydrogen peroxide (H(2)O(2)) aided the photocatalysis decolorization efficiency, although excessive H(2)O(2) reacted with hydroxyl free radicals and decreased the active groups in the system, thereby reducing the photocatalysis activity. An operating temperature of 40 degrees C was conducive to MX-5B decolorization, which was better than operating at room temperature.

  4. TXM-NEXAFS of TiO2-Based Nanostructures

    NASA Astrophysics Data System (ADS)

    Guttmann, P.; Bittencourt, C.; Ke, X.; Van Tendeloo, G.; Umek, P.; Arcon, D.; Ewels, C. P.; Rehbein, S.; Heim, S.; Schneider, G.

    2011-09-01

    In this work, electronic properties of individual TiOx-pristine nanoribbons (NR) prepared by hydrothermal treatment of anatase TiO2 micro-particles were studied using the HZB transmission x-ray microscope (TXM) at the BESSY II undulator beamline U41-FSGM. NEXAFS is ideally suited to study TiO2-based materials because both the O K-edge and Ti L-edge features are very sensitive to the local bonding environment, providing diagnostic information about the crystal structures and oxidation states of various forms of titanium oxides and sub-oxides. TXM-NEXAFS combines full-field x-ray microscopy with spectroscopy, allowing the study of the electronic structure of individual nanostructures with spatial resolution better than 25 nm and a spectral resolution of up to E/ΔE = 10000. The typical image field in TXM-NEXAFS measurements is about 10 μm×10 μm, which is large compared to the individual nanoparticle. Therefore, one image stack already contains statistically significant data. In addition, the directional electric field vector (Ē) of the x-rays can be used as a "search tool" for the direction of chemical bonds of the atom selected by its absorption edge.

  5. Synthesis of visible light-activated TiO 2 photocatalyst via surface organic modification

    NASA Astrophysics Data System (ADS)

    Jiang, Dong; Xu, Yao; Hou, Bo; Wu, Dong; Sun, Yuhan

    2007-05-01

    A visible light-activated TiO 2 photocatalyst was successfully synthesized by the surface organic modification to sol-gel-hydrothermal synthesized TiO 2. The surface hydroxyls of TiO 2 nanoparticles reacted with the active -NCO groups of tolylene diisocyanate (TDI) to form a surface complex that was confirmed by the FT-IR and XPS spectra. Due to the existence of surface complex, the absorption edge of as-prepared TDI-modified TiO 2 nanomaterial extended well into visible region. Compared with unmodified TiO 2 and Degussa P25, the TDI-modified TiO 2 photocatalysts showed higher activity for the photocatalytic degradation of methylene blue under visible light irradiation.

  6. Microwave irradiation induced band gap tuning of MoS2-TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Shakya, Jyoti; Mohanty, T.

    2016-05-01

    The MoS2-TiO2 nanocomposites have been synthesized by sol-gel method and characterized by different microscopic and spectroscopic techniques. The crystallinity of these nanocomposites has been confirmed by X-ray diffraction (XRD) analysis. The Raman spectrum of MoS2-TiO2 nanocomposites consists of three distinct peaks (E1 g, E1 2g and A1g) which are associated with TiO2 and MoS2. The morphological study is carried out by scanning electron microscope. The effect of microwave irradiation on the band gap of MoS2-TiO2 nanocomposites has been investigated; it is observed that the microwave irradiation causes decrease in the band gap of MoS2-TiO2 nanocomposites. The microwave treated MoS2-TiO2 thin films offers a novel process route in treating thin films for commercial applications.

  7. The state of nano-sized titanium dioxide (TiO2) may affect sunscreen performance.

    PubMed

    Tyner, K M; Wokovich, A M; Godar, D E; Doub, W H; Sadrieh, N

    2011-06-01

    In the past several years, there has been a trend in the sunscreen/cosmetics industry to replace micron-sized titanium dioxide (TiO(2)) particles with nanoscale materials. The increased use of nanoscale TiO(2) has resulted in questions about these and other nanoproducts. This study examines the effects of using nanoscale TiO(2) on ultraviolet (UV) attenuation in simple to complex sunscreen formulations. UV light attenuation, product stability, and potential damage to the skin barrier were examined with both nanoscale and microscale TiO(2) particles. Results indicate that none of the formulations decreased the barrier function of the skin and the best UV attenuation occurs when the TiO(2) particles are stabilized with a coating and evenly distributed such as with non-agglomerated coated nanoscale materials. This indicates that nanoscale TiO(2) may have better efficacy while lacking toxicity. PMID:21265867

  8. 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.

  9. Review of the progress in preparing nano TiO2: an important environmental engineering material.

    PubMed

    Wang, Yan; He, Yiming; Lai, Qinghua; Fan, Maohong

    2014-11-01

    TiO2 nanomaterial is promising with its high potential and outstanding performance in photocatalytic environmental applications, such as CO2 conversion, water treatment, and air quality control. For many of these applications, the particle size, crystal structure and phase, porosity, and surface area influence the activity of TiO2 dramatically. TiO2 nanomaterials with special structures and morphologies, such as nanospheres, nanowires, nanotubes, nanorods, and nanoflowers are thus synthesized due to their desired characteristics. With an emphasis on the different morphologies of TiO2 and the influence factors in the synthesis, this review summarizes fourteen TiO2 preparation methods, such as the sol-gel method, solvothermal method, and reverse micelle method. The TiO2 formation mechanisms, the advantages and disadvantages of the preparation methods, and the photocatalytic environmental application examples are proposed as well. PMID:25458670

  10. Enhanced performance of natural dye sensitised solar cells fabricated using rutile TIO2 nanorods

    NASA Astrophysics Data System (ADS)

    Akila, Y.; Muthukumarasamy, N.; Agilan, S.; Mallick, Tapas K.; Senthilarasu, S.; Velauthapillai, Dhayalan

    2016-08-01

    Due to the lower cost, natural dye molecules are good alternatives for the ruthenium based sensitizers in the dye-sensitized solar cells. In this article, we have reported the natural sensitizer based dye-sensitized solar cells fabricated using TiO2 nanorods. Rutile phase TiO2 nanorods have been synthesized by template free hydrothermal method which results in TiO2 nanorods in the form of acropora corals. These TiO2 nanorods have been sensitized by flowers of Sesbania grandiflora, leaves of Camellia sinensis and roots of Rubia tinctorum. The maximum conversion efficiency of 1.53% has been obtained for TiO2 nanorods based solar cells sensitized with the leaves of Camellia sinensis. The flowers of Sesbania grandiflora and roots of Rubia tinctorum sensitized TiO2 nanorods based solar cells exhibited an efficiency of 0.65% and 1.28% respectively.

  11. Antibacterial effect of silver modified TiO2/PECVD films

    NASA Astrophysics Data System (ADS)

    Hájková, P.; Patenka, P. Å.; Krumeich, J.; Exnar, P.; Kolouch, A.; Matoušek, J.; Kočí, P.

    2009-08-01

    This paper deals with photocatalytic activity of silver treated TiO2 films. The TiO2 films were deposited on glass substrates by plasma enhanced chemical vapor deposition (PECVD) in a vacuum reactor with radio frequency (RF) low temperature plasma discharge in the mixture of oxygen and titanium isopropoxide vapors (TTIP). The depositions were performed under different deposition conditions. Subsequently, the surface of TiO2 films was modified by deposition of silver nanoparticles. Photocatalytic activity of both silver modified and unmodified TiO2 films was determined by decomposition of the model organic matter (acid orange 7). Selected TiO2 samples were used for tests of antibacterial activity. These tests were performed on Gram-negative bacteria Escherichia coli. The results clearly proved that presence of silver clusters resulted in enhancement of the photocatalytic activity, which was up to four times higher than that for pure TiO2 films.

  12. Effect of calcination temperature on the photocatalytic properties of electrospun TiO2 nanofibers.

    PubMed

    Lee, Young-In; Lee, Jong-Sik; Park, Eun-Sil; Jang, Dae-Hwan; Lee, Jae-Eun; Kim, Kahee; Myung, Nosang V; Choa, Yong-Ho

    2014-10-01

    In this study, TiO2 nanofibers with a high aspect ratio and a large specific surface area were synthesized using the electrospinning technique, and the effect of calcination temperature on their crystal structure, diameter, specific surface area and photocatalytic activity was systematically investigated. The electrospun, as-prepared PVP/TTIP nanofibers were several tens of micrometers in length with a diameter of 74 nm. TiO2 nanofibers with an average diameter of 50 nm were prepared after calcination at various temperatures. The calcination temperature significantly influenced the photocatalytic and material properties of TiO2 including grain size and specific surface area. When compared to other nanostructured TiO2 materials, such as commercial TiO2 nanoparticles (P25, Degussa), the TiO2 nanofibers exhibited greater photocatalytic activity for the degradation of acetaldehyde and ammonia. PMID:25942911

  13. Conducting Interface in Oxide Homojunction: Understanding of Superior Properties in Black TiO2.

    PubMed

    Lü, Xujie; Chen, Aiping; Luo, Yongkang; Lu, Ping; Dai, Yaomin; Enriquez, Erik; Dowden, Paul; Xu, Hongwu; Kotula, Paul G; Azad, Abul K; Yarotski, Dmitry A; Prasankumar, Rohit P; Taylor, Antoinette J; Thompson, Joe D; Jia, Quanxi

    2016-09-14

    Black TiO2 nanoparticles with a crystalline core and amorphous-shell structure exhibit superior optoelectronic properties in comparison with pristine TiO2. The fundamental mechanisms underlying these enhancements, however, remain unclear, largely due to the inherent complexities and limitations of powder materials. Here, we fabricate TiO2 homojunction films consisting of an oxygen-deficient amorphous layer on top of a highly crystalline layer, to simulate the structural/functional configuration of black TiO2 nanoparticles. Metallic conduction is achieved at the crystalline-amorphous homointerface via electronic interface reconstruction, which we show to be the main reason for the enhanced electron transport of black TiO2. This work not only achieves an unprecedented understanding of black TiO2 but also provides a new perspective for investigating carrier generation and transport behavior at oxide interfaces, which are of tremendous fundamental and technological interest. PMID:27482629

  14. Structural and Optical Characterization of Synthesized TiO2 Nanopowder Using Sol-Gel Technique

    NASA Astrophysics Data System (ADS)

    Lourduraj, S.; Williams, R. Victor

    2016-02-01

    The nanocrystalline TiO2 powder was synthesized by sol-gel method. The XRD analysis reveals that TiO2 powder was highly crystalline (anatase phase) and nanostructured with tetragonal system. The average crystallite size after calcined at 673K is found to be 7.7nm. The surface morphological studies using scanning electron microscopy (SEM) exhibit that the formation of nanosized TiO2 particles with less densification nature. Atomic force microscopy (AFM) topography exhibits the uniform distribution of spherical-shaped particles. The energy dispersive X-ray spectroscopy (EDX) confirms the presence of Titanium and Oxygen in synthesized TiO2 nanopowder. The value of optical bandgap of TiO2 nanopowder calculated from UV-Visible spectrum is 3.45eV. The presence of TiO2 particles is confirmed from the dominant fourier transform infrared (FTIR) peaks at 621cm-1 and 412cm-1.

  15. Photocatalytic activity of TiO2 nanomaterials for methylene blue dye degradation

    NASA Astrophysics Data System (ADS)

    Lee, Deuk Yong; Son, Siwon; Jeon, Min-Seok; Lee, Myung-Hyun; Kim, Bae-Yeon

    2016-04-01

    TiO2 nanomaterials were prepared by a sol-gel derived electrospinning, calcination from 500°C to 650°C, and subsequent mechanical grinding to investigate the effect of calcination temperature on crystal structure, crystallinity, and photocatalytic activity of methylene blue (MB). XRD results indicated that TiO2 nanorods calcined at 500°C is composed of anatase TiO2 only. However, mixed crystals of anatase and rutile were observed for TiO2 calcined above 550°C. Higher MB degradation was found for the TiO2 nanorods calcined at 550°C probably due to the mixed crystals and larger surface area. However, the improved photocatalytic activity was achieved for TiO2 nanotube due to the synergic combinations of mixed crystals, larger specific surface area, and light trapping effect.

  16. Ammonia sensing behaviors of TiO2-PANI/PA6 composite nanofibers.

    PubMed

    Wang, Qingqing; Dong, Xianjun; Pang, Zengyuan; Du, Yuanzhi; Xia, Xin; Wei, Qufu; Huang, Fenglin

    2012-01-01

    Titanium dioxide-polyaniline/polyamide 6 (TiO(2)-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. TiO(2)-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 TiO(2)-PANI/PA6 composite nanofibers was superior to that of PANI/PA6 composite nanofibers. TiO(2)-PANI/PA6 composite nanofibers had good selectivity to ammonia. It was also found that the content of TiO(2) had a great influence on both the morphology and the sensing property of TiO(2)-PANI/PA6 composite nanofibers. PMID:23235446

  17. Surface Treatment for Effective Dye Adsorption on Nanocrystalline TiO2

    NASA Astrophysics Data System (ADS)

    Yanagida, Masatoshi; Han, Chen; Han, Liyuan

    2012-10-01

    To improve the efficiency of dye-sensitized solar cells (DSCs) by controlling dye adsorption on TiO2 surface, the effect of surface treatments on the properties of [NBu4]2[Ru(Htcterpy)(NCS)3] (black dye; [NBu4]: tetrabutylammonium cation; H3tcterpy: 4,4',4''-tricarboxy-2,2':6',2''-terpyridine) on nanocrystalline TiO2 films was investigated by analysis of the photovoltaic performance and the electron transport properties. Although the surface treatments do not affect on the condition band edge of TiO2, the amount of dye on TiO2 increases. The enhancement of dye adsorption by treatment of TiO2 in HCl solution is more effective than that by dipping the dye solution containing deoxycholic acid (DCA) as additive. But the charge recombination between an electron in TiO2 and I3- in the electrolyte can be reduced by the DCA treatment.

  18. Electrical Conductivity Characteristic of TiO2 Nanowires From Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Azlishah Othman, Mohd; Faridah Amat, Noor; Hisham Ahmad, Badrul; Rajan, Jose

    2014-04-01

    One dimensional nanostructures of titanium dioxide (TiO2) were synthesized via hydrothermal method by mixing TiO2 as precursor in aqueous solution of NaOH as solvent. Then, heat and washing treatment was applied. Thus obtained wires had diameter ~15nm. TiO2 nanowires will be used as a network in solar cell such dye-sensitized solar cell in order to improve the performance of electron movement in the device. To improve the performance of electron movement, the characteristics of TiO2 nanowires have been analyses using field emission scanning electron microscopy (FESEM) analysis, x-ray diffractometer (XRD) analysis and brunauer emmett teller (BET) analysis. Finally, electrical conductivity of TiO2 nanowires was determined by measuring the resistance of the TiO2 nanowires paste on microscope glass.

  19. In situ growth of TiO2 in interlayers of expanded graphite for the fabrication of TiO2-graphene with enhanced photocatalytic activity.

    PubMed

    Jiang, Baojiang; Tian, Chungui; Zhou, Wei; Wang, Jianqiang; Xie, Ying; Pan, Qingjiang; Ren, Zhiyu; Dong, Youzhen; Fu, Dan; Han, Jiale; Fu, Honggang

    2011-07-18

    We present a facile route for the preparation of TiO(2)-graphene composites by in situ growth of TiO(2) in the interlayer of inexpensive expanded graphite (EG) under solvothermal conditions. A vacuum-assisted technique combined with the use of a surfactant (cetyltrimethylammonium bromide) plays a key role in the fabrication of such composites. Firstly, the vacuum environment promotes full infusion of the initial solution containing Ti(OBu)(4) and the surfactant into the interlayers of EG. Subsequently, numerous TiO(2) nanoparticles uniformly grow in situ in the interlayers with the help of the surfactant, which facilitates the exfoliation of EG under the solvothermal conditions in ethanol, eventually forming TiO(2)-graphene composites. The as-prepared samples have been characterized by Raman and FTIR spectroscopies, SEM, TEM, AFM, and thermogravimetic analysis. It is shown that a large number of TiO(2) nanoparticles homogeneously cover the surface of high-quality graphene sheets. The graphene exhibits a multi-layered structure (5-7 layers). Notably, the TiO(2)-graphene composite (only 30 wt % of which is TiO(2)) synthesized by subsequent thermal treatment at high temperature under nitrogen shows high photocatalytic activity in the degradation of phenol under visible and UV lights in comparison with bare Degussa P25. The enhanced photocatalytic performance is attributed to increased charge separation, improved light absorbance and light absorption width, and high adsorptivity for pollutants.

  20. One-pot synthesis of peacock-shaped TiO2 light scattering layer with TiO2 nanorods film for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Sik; Kim, Young-Jea; Lee, Wonjoo; Kang, Soon Hyung

    2013-05-01

    A titanium dioxide (TiO2) film, showing distinctive functions and morphology, was prepared using the hydrothermal method by controlling the ratio of HCl:CH3COOH in acidic medium. A one-dimensional (1-D) TiO2 nanorod (NR) film was synthesized with a length of 2 μm using a 1:2 ratio of HCl:CH3COOH, whereas a 1-D TiO2 NR film with peacock shaped TiO2 nanobundles as a light scattering layer (LSL) was acquired by employing a 2:1 ratio of HCl:CH3COOH. This LSL exhibited remarkable dual functions with respect to high light harvesting, which was attributable to the large surface area of the micrometer-sized TiO2 nanobundles, consisting of small-sized TiO2 NRs of 30-40 nm in diameter and a light scattering effect in the long wavelength region of 550-700 nm. Accordingly, the dual functions of the LSL resulted in a sharp increase in conversion efficiency (3.93%) that was about twice that (1.49%) of TiO2 NR film synthesized using a 1:2 ratio of HCl:CH3COOH. In particular, a considerably enhanced short-circuit photocurrent (Jsc) was mainly responsible for the resulting increase in overall efficiency with a moderate increase in fill factor and slightly reduced open-circuit voltage.

  1. Eco-friendly synthesis of TiO2, Au and Pt doped TiO2 nanoparticles for dye sensitized solar cell applications and evaluation of toxicity

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Kumaraguru, S.; Bhakyaraj, K.; Thirumal, S.; Arumugam, A.

    2016-04-01

    Driven by the demand of pure TiO2, Au and Pt doped TiO2 NPs were successfully synthesized using Terminalia arjuna bark extract. The eco-friendly synthesized NPs were characterized by UV-Vis-DRS, ATR-FT-IR, PL, XRD, Raman, SEM with EDX and TEM analysis. The synthesized NPs were investigation for dye sensitized solar cell applications. UV-Vis-Diffused Reflectance Spectra clearly showed that the expected TiO2 inter band absorption below 306 nm, incorporation of gold shows surface plasma resonant (SPR) near 555 nm and platinum incorporated TiO2 NPs shows absorbance at 460 nm. The energy conversion efficiency for Au doped TiO2 NPs when compared to pure and Pt doped TiO2 NPs. In addition to that, Au noble metal present TiO2 matrix and an improve open-circuit voltage (Voc) of DSSC. Synthesized NPs was evaluated into antibacterial and antifungal activities by disk diffusion method. It is observed that NPs have not shown any activities in all tested bacterial and fungal strains. In this eco-friendly synthesis method to provide non toxic and environmental friendly nanomaterials can be used for solar energy device application.

  2. Investigation of photocatalytic degradation of phenol by Fe(III)-doped TiO2 and TiO2 nanoparticles

    PubMed Central

    2014-01-01

    In this study Fe (III)-doped TiO2 nanoparticles were synthesized by sol–gel method at two atomic ratio of Fe/Ti, 0.006 and 0.034 percent. Then the photoactivity of them was investigated on degradation of phenol under UV (<380 nm) irradiation and visible light (>380 nm). Results showed that at appropriate atomic ratio of Fe to Ti (% 0.034) photoactivity of Fe(III)–doped TiO2 nanoparticles increased. In addition, the effects of various operational parameters on photocatalytic degradation, such as pH, initial concentration of phenol and amount of photocatalyst were examined and optimized. At all different initial concentration, highest degradation efficiency occurred at pH = 3 and 0.5 g/L Fe(III)–doped TiO2 dosage. With increase in initial concentration of phenol, photocatalytic degradation efficiency decreased. Photoactivity of Fe (III)-doped TiO2 under UV irradiation and visible light at optimal condition (pH = 3 and catalyst dosage = and 0.5 g/L) was compared with P25 TiO2 nanoparticles. Results showed that photoactivity of Fe(III)-doped TiO2 under visible light was more than P25 TiO2 photoactivity, but it was less than P25 TiO2 photoactivity under UV irradiation. Also efficiency of UV irradiation alone and amount of phenol adsorption on Fe(III)-doped TiO2 at dark condition was investigated. PMID:25105016

  3. Investigation of photocatalytic degradation of phenol by Fe(III)-doped TiO2 and TiO2 nanoparticles.

    PubMed

    Hemmati Borji, Saeedeh; Nasseri, Simin; Mahvi, Amir Hossein; Nabizadeh, Ramin; Javadi, Amir Hossein

    2014-01-01

    In this study Fe (III)-doped TiO2 nanoparticles were synthesized by sol-gel method at two atomic ratio of Fe/Ti, 0.006 and 0.034 percent. Then the photoactivity of them was investigated on degradation of phenol under UV (<380 nm) irradiation and visible light (>380 nm). Results showed that at appropriate atomic ratio of Fe to Ti (% 0.034) photoactivity of Fe(III)-doped TiO2 nanoparticles increased. In addition, the effects of various operational parameters on photocatalytic degradation, such as pH, initial concentration of phenol and amount of photocatalyst were examined and optimized. At all different initial concentration, highest degradation efficiency occurred at pH = 3 and 0.5 g/L Fe(III)-doped TiO2 dosage. With increase in initial concentration of phenol, photocatalytic degradation efficiency decreased. Photoactivity of Fe (III)-doped TiO2 under UV irradiation and visible light at optimal condition (pH = 3 and catalyst dosage = and 0.5 g/L) was compared with P25 TiO2 nanoparticles. Results showed that photoactivity of Fe(III)-doped TiO2 under visible light was more than P25 TiO2 photoactivity, but it was less than P25 TiO2 photoactivity under UV irradiation. Also efficiency of UV irradiation alone and amount of phenol adsorption on Fe(III)-doped TiO2 at dark condition was investigated.

  4. Hunting for the elusive shallow traps in TiO2 anatase.

    PubMed

    Antila, Liisa J; Santomauro, Fabio G; Hammarström, Leif; Fernandes, Daniel L A; Sá, Jacinto

    2015-07-11

    Understanding electron mobility on TiO2 is crucial because of its applications in photocatalysis and solar cells. This work shows that shallow traps believed to be involved in electron migration in TiO2 conduction band are formed upon band gap excitation, i.e., are not pre-existing states. The shallow traps in TiO2 results from large polarons and are not restricted to surface.

  5. [TiO2-Induced Photodegradation of Levofloxacin by Visible Light and Its Mechanism].

    PubMed

    Guo, Hong-sheng; Liu, Ya-nan; Qiao, Qi; Wei, Hong; Dong, Cheng-xing; Xue, Jie; Li, Ke-bin

    2015-05-01

    Levofloxacin is an emerging pollutant. Single levofloxacin and TiO2 have no visible-light activity. However, photodegradation of levofloxacin dramatically enhanced in the presence of TiO2 under visible light irradiation. Considering this finding, he photodegradation of levofloxacin over TiO2 was investigated under visible light irradiation. Effects of TiO2 dosage, levofloxacin concentration, and solution pH on levofloxacin photodegradation were examined by monitoring its concentration decay with time. The results showed that levofloxacin photodegradation fitted the Langmuir-Hinshelwood kinetic model. Solution pH, TiO2 dose, and levofloxacin concentration had significant effects on the photodegradation rates. In addition, batch adsorption experiments revealed that adsorption of levofloxacin on TiO2 conformed to the pseudo-second-order kinetics and the Langmuir isotherm. DRS spectrum of levofloxacin-adsorbed TiO2 suggested that a surface complex was formed between levofloxacin and TiO2. Addition of radical scavengers and N2-degassing affecting levofloxacin photodegradation indicated that the superoxide ion radical was mainly active species. UV-Vis spectra of a deaerated TiO2 and levofloxacin suspensions further confirmed that the electron injection into TiO2 conduction band took place under visible light irradiation. Based on these results, a charge-transfer mechanism initiated by photoexcitation of TiO2/ levofloxacin surface complex was proposed for levofloxacin photocatalytic degradation over TiO2 under visible light. This study indicates that the charge-transfer-complex-mediated photocatalytic technique has promising applications in the removal of colorless organic pollutants.

  6. TiO2-sludge carbon enhanced catalytic oxidative reaction in environmental wastewaters applications.

    PubMed

    Athalathil, Sunil; Erjavec, Boštjan; Kaplan, Renata; Stüber, Frank; Bengoa, Christophe; Font, Josep; Fortuny, Agusti; Pintar, Albin; Fabregat, Azael

    2015-12-30

    The enhanced oxidative potential of sludge carbon/TiO2 nano composites (SNCs), applied as heterogeneous catalysts in advanced oxidation processes (AOPs), was studied. Fabrification of efficient SNCs using different methods and successful evaluation of their catalytic oxidative activity is reported for the first time. Surface modification processes of hydrothermal deposition, chemical treatment and sol-gel solution resulted in improved catalytic activity and good surface chemistry of the SNCs. The solids obtained after chemical treatment and hydrothermal deposition processes exhibit excellent crystallinity and photocatalytic activity. The highest photocatalytic rate was obtained for the material prepared using hydrothermal deposition technique, compared to other nanocomposites. Further, improved removal of bisphenol A (BPA) from aqueous phase by means of catalytic ozonation and catalytic wet air oxidation processes is achieved over the solid synthesized using chemical treatment method. The present results demonstrate that the addition of TiO2 on the surface of sludge carbon (SC) increases catalytic oxidative activity of SNCs. The latter produced from harmful sludge materials can be therefore used as cost-effective and efficient sludge derived catalysts for the removal of hazardous pollutants.

  7. Interstitial Boron-Doped TiO2 Thin Films: The Significant Effect of Boron on TiO2 Coatings Grown by Atmospheric Pressure Chemical Vapor Deposition.

    PubMed

    Quesada-González, Miguel; Boscher, Nicolas D; Carmalt, Claire J; Parkin, Ivan P

    2016-09-28

    The work presented here describes the preparation of transparent interstitial boron-doped TiO2 thin-films by atmospheric pressure chemical vapor deposition (APCVD). The interstitial boron-doping, on TiO2, proved by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), is shown to enhance the crystallinity and significantly improve the photocatalytic activity of the TiO2 films. The synthesis, highly suitable for a reel-to-reel process, has been carried out in one step. PMID:27622709

  8. A comparative study of doped and un-doped sol-gel TiO2 and P25 TiO2 (photo)electrodes.

    PubMed

    Pooarporn, Y; Worayingyong, A; Wörner, M; Songsiriritthigul, P; Braun, A M

    2007-01-01

    Doped and undoped titanium dioxide films have been deposited on indium tin oxide glass using the sol-gel technique. The percentage of rutile in the prepared TiO2, calcined at 823 K and determined by X-ray diffraction, was 23% compared to 24% of rutile in P25-TiO2. Cerium doped TiO2 showed mainly the anatase phase, as characterised by both X-ray diffraction and Raman spectroscopy. The electrochemical and photoelectrochemical properties of the films were studied by cyclic voltammetry and electrochemical impedance spectroscopy. The (photo)electrochemical characteristics of the different films are reported and discussed.

  9. Interstitial Boron-Doped TiO2 Thin Films: The Significant Effect of Boron on TiO2 Coatings Grown by Atmospheric Pressure Chemical Vapor Deposition.

    PubMed

    Quesada-González, Miguel; Boscher, Nicolas D; Carmalt, Claire J; Parkin, Ivan P

    2016-09-28

    The work presented here describes the preparation of transparent interstitial boron-doped TiO2 thin-films by atmospheric pressure chemical vapor deposition (APCVD). The interstitial boron-doping, on TiO2, proved by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), is shown to enhance the crystallinity and significantly improve the photocatalytic activity of the TiO2 films. The synthesis, highly suitable for a reel-to-reel process, has been carried out in one step.

  10. Self-cleaning properties of TiO2/palygorskite and TiO2/halloysite nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Panagiotaras, Dionisios; Kaplani, Eleni; Stathatos, Elias; Papoulis, Dimitrios

    2014-10-01

    Tubular halloysite and microfibrous palygorskite clay mineral combined with nanocrystalline TiO2 are involved in the preparation of nanocomposite films on glass substrates via sol-gel route at 450°C. The synthesis employing nonionic surfactant molecule as pore directing agent along with the acetic acid-based sol-gel route without addition of water molecules. Drying and thermal treatment of composite films ensure elimination of organic material lead to the formation of TiO2 nanoparticles homogeneously distributed on the palygorskite and halloysite surfaces. Nanocomposite films without cracks of active anatase crystal phase on palygorskite and halloysite surfaces are characterized by microscopy techniques, UV-Vis spectroscopy, and porosimetry methods in order to examine their structural properties. The composite palygorskite-TiO2 and halloysite/TiO2 films with variable quantities of palygorskite and halloysite were tested as photocatalysts in the photo-oxidation of Basic Blue 41 azo dye in water. These nanocomposite films proved to be most promising photocatalysts and highly effective to dye's decoloration in spite of small amount of palygorskite/TiO2 or halloysite/TiO2 catalyst immobilized onto glass substrates.

  11. Positron annihilation lifetime characterization of oxygen ion irradiated rutile TiO2

    NASA Astrophysics Data System (ADS)

    Luitel, Homnath; Sarkar, A.; Chakrabarti, Mahuya; Chattopadhyay, S.; Asokan, K.; Sanyal, D.

    2016-07-01

    Ferromagnetic ordering at room temperature has been induced in rutile phase of TiO2 polycrystalline sample by O ion irradiation. 96 MeV O ion induced defects in rutile TiO2 sample has been characterized by positron annihilation spectroscopic techniques. Positron annihilation results indicate the formation of cation vacancy (VTi, Ti vacancy) in these irradiated TiO2 samples. Ab initio density functional theoretical calculations indicate that in TiO2 magnetic moment can be induced either by creating Ti or O vacancies.

  12. 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

  13. Annealing of TiO2 Films Deposited on Si by Irradiating Nitrogen Ion Beams

    SciTech Connect

    Yokota, Katsuhiro; Yano, Yoshinori; Miyashita, Fumiyoshi

    2006-11-13

    Thin TiO2 films were deposited on Si at a temperature of 600 deg. C by an ion beam assisted deposition (IBAD) method. The TiO2 films were annealed for 30 min in Ar at temperatures below 700 deg. C. The as-deposited TiO2 films had high permittivities such 200 {epsilon}o and consisted of crystallites that were not preferentially oriented to the c-axis but had an expanded c-axis. On the annealed TiO2 films, permittivities became lower with increasing annealing temperature, and crystallites were oriented preferentially to the (110) plane.

  14. A comparative study of TiO2 nanoparticles synthesized in premixed and diffusion flames

    NASA Astrophysics Data System (ADS)

    Ma, Hsiao-Kang; Yang, Hsiung-An

    2010-12-01

    Previous studies have been shown that synthesis of titania (TiO2) crystalline phase purity could be effectively controlled by the oxygen concentration through titanium tetra-isopropoxide (TTIP) via premixed flame from a Bunsen burner. In this study, a modified Hencken burner was used to synthesize smaller TiO2 nanoparticles via short diffusion flames. The frequency of collisions among particles would decrease and reduce TiO2 nanoparticle size in a short diffusion flame height. The crystalline structure of the synthesized nanoparticles was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) measurements. The characteristic properties of TiO2 nanoparticles synthesized from a modified Hencken burner were compared with the results from a Bunsen burner and commercial TiO2 (Degussa P25). The results showed that the average particle size of 6.63 nm from BET method was produced by a modified Hencken burner which was smaller than the TiO2 in a Bunsen burner and commercial TiO2. Moreover, the rutile content of TiO2 nanoparticles increased as the particle collecting height increased. Also, the size of TiO2 nanoparticles was highly dependent on the TTIP loading and the collecting height in the flame.

  15. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    PubMed

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2.

  16. Mesoporous submicrometer TiO(2) hollow spheres as scatterers in dye-sensitized solar cells.

    PubMed

    Dadgostar, Shabnam; Tajabadi, Fariba; Taghavinia, Nima

    2012-06-27

    Hierarchical submicrometer TiO2 hollow spheres with outer diameter of 300-700 nm and shell thickness of 200 nm are synthesized by liquid phase deposition of TiO2 over carbon microspheres as sacrificial templates. The final TiO2 hollow spheres are applied as a scattering layer on top of a transparent nanocrystalline TiO2 film, serving as the photoanode of a dye-sensitized solar cell (DSC). In addition to efficient light scattering, the mesoporous structure of TiO2 hollow spheres provides a high surface area, 74 m(2)/g, which allows for higher dye loading. This dual functioning suggests that TiO2 hollow spheres may be good replacements for conventional TiO2 spheres as scatterers in DSCs. A high efficiency of 8.3% is achieved with TiO2 hollow spheres, compared with 6.0% for the electrode with 400 nm spherical TiO2 scatterers, at identical conditions. PMID:22606936

  17. Improvement of solar energy conversion with Nb-incorporated TiO2 hierarchical microspheres.

    PubMed

    Hoang, Son; Ngo, Thong Q; Berglund, Sean P; Fullon, Raymond R; Ekerdt, John G; Mullins, C Buddie

    2013-07-22

    Niobium-modified TiO2 hierarchical spherical micrometer-size particles, which consist of many nanowires, are synthesized by solvothermal synthesis and studied as photoelectrodes for water photo-oxidation and dye-sensitized solar cell (DSSC) applications. Incorporation of Nb leads to a rutile-to-anatase TiO2 phase transition in the TiO2 hierarchical spheres (HSs), with the anatase percentage increasing from 0% for the pristine TiO2 HSs to 47.6% for the 1.82 at.% Nb-incorporated TiO2 sample. Incorporation of Nb leads to significant improvements in water photo-oxidation with the photocurrents reaching 70.5 μA cm(-2) at 1.23 V versus the reversible hydrogen electrode, compared with 28.3 μA cm(-2) for the pristine TiO2 sample. The photoconversion efficiency of Nb:TiO2 HS-based DSSCs reaches 6.09±0.15% at 0.25 at.% Nb, significantly higher than that for the pristine TiO2 HS cells (3.99±0.02%). In addition, the incident-photon-to-current efficiency spectra for DSSCs show that employing TiO2 and Nb:TiO2 HSs provides better light harvesting, especially of long-wavelength photons, than anatase TiO2 nanoparticle-based DSSCs. PMID:23512241

  18. [Preparation of mixed crystal TiO2 nanoparticles and photocatalytic degradation of toxic organic pollutants].

    PubMed

    Deng, An-Ping; Yang, Jing; Wang, Shu-Lian; Huang, Ying-Ping; Yang, Yong

    2010-12-01

    Mixed crystal TiO2 nanoparticles were prepared from a precursor of TiO2 by hydrothermal-steam method. The effects of the reaction temperature and the reaction time on the photocatalytic activity of the brookite TiO2 were studied. The TiO2 samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Photocatalytic degradation of organic dye sulforhodamine B (SRB) under UV light (lambda < or = 387 nm) was used as probe reaction to evaluate the properties of the TiO2. The result showed that TiO2 prepared under 150 degrees C for 24 h had high photocatalytic activity. The size of the mixed crystal TiO2 was 14.20 nm. Brookite and anatase phase of the mixed crystal TiO2 were 63.6% and 36.4%, respectively. The dye discoloration and degradation rates were tracked, and the intermediate products hydrogen peroxide (H2O2) and hydrogen radicals (*OH) were determined during the photocatalytic experiments. The results indicated that photocatalytic degradation of brookite TiO2 mainly referred to the *OH radical mechanism. After 5 h, the mineralization and oxidation rates of SRB and 2,4-DCP mineralization were 89% and 78%, respectively. The catalyst showed good stability with no significant changes in catalytic properties after 5 cycles of SRB photocatalytic degradation experiments.

  19. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    PubMed Central

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  20. Tuning hydrophobicity of TiO2 layers with silanization and self-assembled nanopatterning.

    PubMed

    Van, Trong Nghia; Lee, Young Keun; Lee, Jaesang; Park, Jeong Young

    2013-03-01

    The wettability of TiO2 layers is controlled by forming highly ordered arrays of nanocones using nanopatterning, based on self-assembly and dry etching. Nanopatterning of TiO2 layers is achieved via formation of self-assembled monolayers of SiO2 spheres fabricated using the Langmuir-Blodgett technique, followed by dry etching. Three types of TiO2 layers were fabricated using the sol-gel technique, sputtering, and thermal process in order to address the relationship between the wettability and the structure of TiO2 nanostructures. Compared to a thin film TiO2 layer, the nanopatterned TiO2 samples show a smaller static water contact angle (i.e., where the water contact angle decreases as the etching time increases), which is attributed to the Wenzel equation. When TiO2 layers are coated by 1H,1H,2H,2H-perfluorooctyltrichlorosilane, we observed the opposite behavior, exhibiting superhydrophobicity (up to contact angle of 155°) on the nanopatterned TiO2 layers. Self-assembled nanopatterning of the TiO2 layer may provide an advanced method for producing multifunctional transparent layers with self-cleaning properties.

  1. Sonochemical synthesis of TiO(2 nanoparticles on graphene for use as photocatalyst.

    PubMed

    Guo, Jingjing; Zhu, Shenmin; Chen, Zhixin; Li, Yao; Yu, Ziyong; Liu, Qinglei; Li, Jingbo; Feng, Chuanliang; Zhang, Di

    2011-09-01

    Using ultrasonication we succeed in a controlled incorporation of TiO(2) nanoparticles on the graphene layers homogeneously in a few hours. The average size of the TiO(2) nanoparticles was controlled at around 4-5 nm on the sheets without using any surfactant, which is attributed to the pyrolysis and condensation of the dissolved TiCl(4) into TiO(2) by ultrasonic waves. The photocatalytic activity of the resultant graphene-TiO(2) composites containing 25 wt.% TiO(2) is better than that of commercial pure TiO(2). This is partly due to the extremely small size of the TiO(2) nanoparticles and partly due to the graphene-TiO(2) composite structure consisting of homogeneous dispersion of crystalline TiO(2) nanoparticles on the graphene sheets. As the graphene in the composites has a very good contact with the TiO(2) nanoparticles it enhances the photo-electron conversion of TiO(2) by reducing the recombination of photo-generated electron-hole pairs. PMID:21482166

  2. On the Crystal Structural Control of Sputtered TiO2 Thin Films

    NASA Astrophysics Data System (ADS)

    Jia, Junjun; Yamamoto, Haruka; Okajima, Toshihiro; Shigesato, Yuzo

    2016-07-01

    In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions for the anatase TiO2; the observations further revealed that the anatase phase gradually dominated the crystal structure with increasing film thickness. These results suggest that the bombardment during the sputtering deposition did not obviously affect the TiO2 crystal structure, and this was also confirmed by off-axis magnetron sputtering experiments. We also investigated the mechanism of the effect of Sn impurity doping on the crystal structure using first-principles calculations. It is found that the formation energy of Sn-doped rutile TiO2 is lower than that of Sn-doped anatase TiO2; this suggests that the Sn-doped TiO2 favours the rutile phase. These results offer a guideline for the utilization of selective deposition of rutile and anatase TiO2 thin films in various industrial applications.

  3. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    PubMed

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-06-05

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity.

  4. Structural, morphological, optical and photocatalytic investigation of Ag-doped TiO2

    NASA Astrophysics Data System (ADS)

    Kundu, Virender Singh; Singh, Davender; Maan, A. S.; Tanwar, Amit

    2016-05-01

    The pure and Ag-doped TiO2 nanoparticles were prepared by using Titanium isoproxide (TTIP), silver nitrate sodium hydroxide and sodium hydroxide. The calcined nanoparticles at 400°C were characterized by means of X-ray diffraction (XRD). XRD analyses reveal that the nanoparticles of various doping concentration were having anatase phase. The particle size was calculated by Scherrer formula and was found 11.08 nm for pure TiO2 and 8.86 nm for 6 mol % Ag doped TiO2. The morphology and nature of nanoparticles was analyzed by using scanning electron microscope (SEM), the optical absorption spectra of pure TiO2 and Ag-doped TiO2 nanoparticles showed that absorption edge increases towards longer wavelength from 390 nm (pure) to 450 nm (doped), also band gap energy calculated from Tauc's plot decrease from 3.20eV to 2.92eV with increase in doing. The measurement of photocatalytic properties of pure TiO2 and Ag-doped TiO2 nanoparticles showed that Ag-doped TiO2 degrades MB dye more efficiently than pure TiO2.

  5. Environment-friendly biomimetic synthesis of TiO2 nanomaterials for photocatalytic application

    NASA Astrophysics Data System (ADS)

    Bao, Shu-Juan; Lei, Chao; Xu, Mao-Wen; Cai, Chang-Jun; Jia, Dian-Zeng

    2012-05-01

    We have demonstrated an environment-friendly biomimetic synthesis method for the preparation of TiO2 nanomaterials with different crystal phases and morphologies. This is the first time that it has been found that the crystal phase of TiO2 can be controlled just by using different biotemplates, and cannot be changed by calcination up to 750 °C. In our experiment, anatase TiO2 was obtained by using yeast and albumen templates, while rutile TiO2 was formed by using dandelion pollen as the template.

  6. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    PubMed

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2. PMID:27255319

  7. The role of interfacial effects on enhanced catalytic performance of TiO2 -graphene nanocomposites

    NASA Astrophysics Data System (ADS)

    Chakarov, Dinko; Sellappan, Raja

    2014-03-01

    Graphene-containining TiO2 nanocomposites have significantly higher photocatalytic activity compared to bare TiO2 films. The enhancement is result of improved transport and higher efficiency of the charge carries separation at carbon-TiO2 interface. These effects were assessed by comparison of six anatase-graphene structures, fabricated by different synthesizing techniques and referenced to the performance of TiO2-graphitic-carbon and TiO2-Au thin films. The work was financially supported by The Nordic Energy Research Council through project N-I-S-F-D.

  8. Nitrogen doped TiO2 nano-particles: Phase control by solution combustion method

    NASA Astrophysics Data System (ADS)

    Bapna, Komal; Choudhary, R. J.; Phase, D. M.; Shastri, Sheetal; Prasad, R.; Ahuja, B. L.

    2016-05-01

    N-doped TiO2 nano powders were prepared by sol-gel solution combustion method. The influence of different fuels (urea and citric acid) used in obtaining N-TiO2 nano particles in similar conditions (heat treatment, amount of precursors) has been investigated. The growth of different phases of TiO2 (anatase and rutile) is strongly affected by the ligands and the dehydration reaction. Reduction in the band gap of TiO2 and features observed in the XPS spectra confirm the incorporation of N into TiO2 matrix.

  9. Tuning hydrophobicity of TiO2 layers with silanization and self-assembled nanopatterning.

    PubMed

    Van, Trong Nghia; Lee, Young Keun; Lee, Jaesang; Park, Jeong Young

    2013-03-01

    The wettability of TiO2 layers is controlled by forming highly ordered arrays of nanocones using nanopatterning, based on self-assembly and dry etching. Nanopatterning of TiO2 layers is achieved via formation of self-assembled monolayers of SiO2 spheres fabricated using the Langmuir-Blodgett technique, followed by dry etching. Three types of TiO2 layers were fabricated using the sol-gel technique, sputtering, and thermal process in order to address the relationship between the wettability and the structure of TiO2 nanostructures. Compared to a thin film TiO2 layer, the nanopatterned TiO2 samples show a smaller static water contact angle (i.e., where the water contact angle decreases as the etching time increases), which is attributed to the Wenzel equation. When TiO2 layers are coated by 1H,1H,2H,2H-perfluorooctyltrichlorosilane, we observed the opposite behavior, exhibiting superhydrophobicity (up to contact angle of 155°) on the nanopatterned TiO2 layers. Self-assembled nanopatterning of the TiO2 layer may provide an advanced method for producing multifunctional transparent layers with self-cleaning properties. PMID:23413954

  10. Characterization of manufactured TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Motzkus, C.; Macé, T.; Vaslin-Reimann, S.; Ausset, P.; Maillé, M.

    2013-04-01

    Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO2), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

  11. Hydrogen donor in anatase TiO2

    NASA Astrophysics Data System (ADS)

    Lavrov, E. V.

    2016-01-01

    An IR absorption study of hydrogen-related defects in natural single-crystalline anatase TiO2 has been carried out. A complex with IR absorption lines at 3412 and 3417 cm-1 is shown to act as a donor with ionization energy of tens of meV. The two lines are identified as stretching local vibrational modes of the O-H bonds of the donor in the neutral and positive charge states, respectively. The defect is unstable against annealing at approximately 300 ∘C and a storage at room temperature on the time scale of a few weeks. These findings suggest that interstitial hydrogen is a plausible model of this defect.

  12. TiO2 doped with nitrogen: synthesis and characterization.

    PubMed

    Abazović, Nadica D; Montone, Amelia; Mirenghi, Luciana; Janković, Ivana A; Comor, Mirjana I

    2008-02-01

    In this study, nitrogen-doped titanium dioxide (TiO2) powders were synthesized in two ways: by heating of titanium hydroxide with urea and by direct hydrolysis of titanium tetraisopropoxide (TTIP) with ammonium hydroxide. The samples were characterized by structural (XRD), analytical (XPS), optical (UV/Vis absorption/reflection and Raman spectroscopy) and morphological (SEM, TEM) techniques. The characterization suggested that the doped materials have anatase crystalline form without any detectable peaks that correspond to dopants. The absorption threshold of titanium dioxide was moved in the visible range of optical spectrum from 3.2 eV to 2.20 eV. Particle sizes of synthesized powders were obtained from XRD measurements and from TEM data ranging from 6-20 nm. XPS and Raman spectroscopy were used for detection of nitrogen in doped samples. PMID:18464379

  13. Fabrication N, F, and N/F-Doped TiO2 Photoelectrodes for Dye-Sensitized Solar Cells.

    PubMed

    Park, Su Kyung; Yun, Tae Kwan; Bae, Jae Young

    2015-08-01

    In this study, pure TiO2, N-doped TiO2, F-doped TiO2, and N/F-doped TiO2 particles were successfully synthesized through the hydrolysis of TiCl4 in the presence of ammonia water and NH4F, respectively. The introduction of doping materials did not affect the crystalline structure. No absorption peak for pure TiO2 was observed above the wavelength of 400 nm. However, the N-doped TiO2 and N/F-doped TiO2 powders exhibited a new absorption peak in the visible light region between 400 and 530 nm. The Jsc value of DSSCs based on the N/F-doped TiO2 electrode was increased by 10% compared to DSSCs using a pure TiO2 electrode, and the energy conversion efficiency was increased by 12%.

  14. N-doped TiO 2: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Di Valentin, Cristiana; Finazzi, Emanuele; Pacchioni, Gianfranco; Selloni, Annabella; Livraghi, Stefano; Paganini, Maria Cristina; Giamello, Elio

    2007-10-01

    Nitrogen doped titanium dioxide is attracting a continuously increasing attention because of its potential as material for environmental photocatalysis. In this paper we review experimental and theoretical work done on this system in our groups in recent years. The analysis is largely based on electron paramagnetic resonance (EPR) spectra and on their interpretation based on high-level ab initio calculations. N-doped anatase TiO 2 contains thermally stable single N-atom impurities either as charged diamagnetic Nb- centers or as neutral paramagnetic Nbrad centers (b stays for bulk). The N-atoms can occupy both interstitial or substitutional positions in the solid, with some evidence for a preference for interstitial sites. All types of N b centers give rise to localized states in the band-gap of the oxide, thus accounting for the related reduction of absorption band edge. The relative abundance of these species depends on the oxidation state of the solid. In fact, upon reduction, oxygen vacancies form and transfer electrons from Ti 3+ ions to the Nbrad with formation of Ti 4+ and Nb-. EPR spectra measured under irradiation show that the N b centers are responsible for visible light absorption with promotion of electrons from the localized N-impurity states to the conduction band or to electron scavengers like O 2 adsorbed on the surface. These results provide an unambiguous characterization of the electronic states associated with N-impurities in TiO 2 and a realistic picture of the processes occurring in the solid under irradiation with visible light.

  15. (In,Sn)2O3/TiO2/Pt Schottky-type diode switch for the TiO2 resistive switching memory array

    NASA Astrophysics Data System (ADS)

    Shin, Yong Cheol; Song, Jaewon; Kim, Kyung Min; Choi, Byung Joon; Choi, Seol; Lee, Hyun Ju; Kim, Gun Hwan; Eom, Taeyong; Hwang, Cheol Seong

    2008-04-01

    A Schottky-type diode switch consisting of a Pt /(In,Sn)2O3/TiO2/Pt stack was fabricated for applications to cross-bar type resistive-switching memory arrays. The high (0.55eV) and low potential barrier at the TiO2/Pt and TiO2/(In,Sn)2O3 junctions, respectively, constitute the rectifying properties of the stacked structure. The forward/reverse current ratio was as high as ˜1.6×104 at an applied voltage of ˜1V. When Pt /TiO2/Pt memory was connected to this diode in series, there was an insignificant interference on the memory function from the diode under the forward bias and virtually no resistive switching under a reverse bias.

  16. Highly recoverable TiO2-GO nanocomposites for stormwater disinfection.

    PubMed

    Wang, Gen; Feng, Wenjun; Zeng, Xiangkang; Wang, Zhouyou; Feng, Chuanping; McCarthy, David T; Deletic, Ana; Zhang, Xiwang

    2016-05-01

    A highly recoverable titanium dioxide-graphene oxide (TiO2-GO) composite was developed by a facile method of ultrasonic treatment of GO nanosheets and TiO2 nanoparticles, which should overcome the separation problem of nanosized TiO2 from treated water. Separability of the prepared samples was systematically investigated by gravity settling experiments. The samples' photocatalytic activity for stormwater disinfection was also studied under the irradiation of a solar simulator. The results demonstrated that TiO2-GO showed high efficient separability due to its accelerated settling behaviour. Zeta-potential analysis showed that the accelerated sedimentation of the catalyst was attributed to the aggregation of TiO2-GO resulting from the electrostatic attraction between TiO2 and GO. The TiO2-GO composite with a mass ratio of 100:2 (TiO2-2%GO) achieved both higher separability and good photocatalytic activity for stormwater disinfection. Its suspension became clear (turbidity < 50 NTU) after 8 h of sedimentation, while 99.5% of E.coli were deactivated in 90 min. The TiO2-GO composite exhibited excellent durability; no apparent change in the separability of TiO2-2%GO was observed after 10 treatment cycles (15 h in total), while only slight decrease in the photocatalytic activity was noted. In conclusion, the developed TiO2-GO composite showed promising results for stormwater disinfection. PMID:26991482

  17. High pressure structural phase transitions of TiO2 nanomaterials

    NASA Astrophysics Data System (ADS)

    Quan-Jun, Li; Bing-Bing, Liu

    2016-07-01

    Recently, the high pressure study on the TiO2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO2-B nanoribbons. Various TiO2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO2 nanoribbons, α-PbO2-type TiO2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. Project supported by the National Basic Research Program of China (Grant No. 2011CB808200), the National Natural Science Foundation of China (Grant Nos. 11374120, 11004075, 10979001, 51025206, 51032001, and 21073071), and the Cheung Kong Scholars Programme of China.

  18. Plasma surface modified TiO2 nanoparticles: improved photocatalytic oxidation of gaseous m-xylene.

    PubMed

    Sumitsawan, Sulak; Cho, Jai; Sattler, Melanie L; Timmons, Richard B

    2011-08-15

    Titanium dioxide (TiO(2)) is a preferred catalyst for photocatalytic oxidation of many air pollutants. In an effort to enhance its photocatalytic activity, TiO(2) was modified by pulsed plasma treatment. In this work, TiO(2) nanoparticles, coated on a glass plate, were treated with a plasma discharge of hexafluoropropylene oxide (HFPO) gas. By appropriate adjustment of discharge conditions, it was discovered that the TiO(2) particles can be either directly fluorinated (Ti-F) or coated with thin perfluorocarbon films (C-F). Specifically, under relatively high power input, the plasma deposition process favored direct surface fluorination. The extent of Ti-F formation increased with increasing power input. In contrast, at lower average power inputs, perfluorocarbon films are deposited on the surface of the TiO(2) particles. The plasma surface modified TiO(2) nanoparticles were subsequently employed as catalysts in the photocatalytic oxidation of m-xylene in air, as carried out inside a batch reactor with closed loop constant gas circulation. Both types of modified TiO(2) were significantly more catalytically active than that of the unmodified particles. For example, the rate constant of m-xylene degradation was increased from 0.012 min(-1) with untreated TiO(2) to 0.074 min(-1) with fluorinated TiO(2). Although it is not possible to provide unequivocal reasons for this increased photocatalytic activity, it is noted that the plasma surface treatment converted the TiO(2) from hydrophilic to highly hydrophobic, which would provide more facile catalyst adsorption of the xylene from the flowing air. Also, based on literature reports, the use of fluorinated TiO(2) reduces electron-hole recombination rates, thus increasing the photocatalytic activity. PMID:21761865

  19. TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

    NASA Astrophysics Data System (ADS)

    Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

    2014-07-01

    A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

  20. TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.

    PubMed

    Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

    2014-07-15

    A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m(2)/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88. PMID:24682063

  1. TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: a comparative study of photo catalysis on acid red 88.

    PubMed

    Balachandran, K; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P

    2014-07-15

    A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m(2)/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

  2. Preparation of hollow TiO2 nanoparticles through TiO2 deposition on polystyrene latex particles and characterizations of their structure and photocatalytic activity

    PubMed Central

    2012-01-01

    In a mixed solvent of water and ethanol, polystyrene/titanium dioxide (PSt/TiO2) composite particles of core-shell structure were prepared by hydrolysis of tetrabutyl titanate in the presence of cationic PSt particles or anionic PSt particles surface-treated using γ-aminopropyl triethoxysilane. Hollow TiO2 particles were obtained through calcination of the PSt/TiO2 core-shell particles to burn off the PSt core or through dissolution of the core by tetrahydrofuran (THF). An alternative process constituted of preheating the PSt/TiO2 particles at 200°C to allow partial crystallization followed by calcination or PSt dissolution by THF. The outcome TiO2 particles thus prepared were examined by TEM, and hollow TiO2 particles were observed. The crystalline phase structure and phase transformation were characterized, which revealed that preheating before the removal of the PSt core was useful to achieve the desired hollow TiO2 particles, and the calcination process was beneficial to the formation of anatase and rutile structures. The tests of TiO2 particles as catalyst in the photodegradation of Rhodamine B demonstrated that a much higher catalytic activity was observed with the TiO2 hollow particles prepared through calcination combined with preheating. PMID:23176612

  3. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells.

    PubMed

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-12-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  4. Hydrothermal Etching Treatment to Rutile TiO2 Nanorod Arrays for Improving the Efficiency of CdS-Sensitized TiO2 Solar Cells

    NASA Astrophysics Data System (ADS)

    Wan, Jingshu; Liu, Rong; Tong, Yuzhu; Chen, Shuhuang; Hu, Yunxia; Wang, Baoyuan; Xu, Yang; Wang, Hao

    2016-01-01

    Highly ordered TiO2 nanorod arrays (NRAs) were directly grown on an F:SnO2 (FTO) substrate without any seed layer by hydrothermal route. For a larger surface area, the second-step hydrothermal treatment in hydrochloric acid was carried out to the as-prepared TiO2 NRAs. The results showed that the center portion of the TiO2 nanorods were dissolved in the etching solution to form a nanocave at the initial etching process. As the etching time extended, the tip parts of the nanocave wall split into lots of nanowires with a reduced diameter, giving rise to a remarkable increase of specific surface area for the TiO2 NRAs. The TiO2 films after etching treatment were sensitized by CdS quantum dots (QDs) to fabricate quantum dot-sensitized solar cells (QDSSCs), which exhibited a significant improvement in the photocurrent density in comparison with that of the un-treated device, this mainly attributed to the enhancement of QD loading and diffused reflectance ability. Through modifying the etching TiO2 films with TiCl4, a relatively high power conversion efficiency (PCE) of 3.14 % was obtained after optimizing the etching time.

  5. An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube arrays for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Quantong; Li, Siqian; Wang, Yi; Ye, Cong; Ruterana, Pierre; Wang, Hao

    2014-12-01

    An efficient photoanode consisting of TiO2 nanoparticle-filled TiO2 nanotube (TNT) arrays is prepared by a sol-gel process through hydrolysis and condensation of titaniumtetrachloride in an aqueous medium containing alcohol and ammonia. By introducing the TiO2 nanoparticles of proper particle size ∼20 nm into TNT arrays, the surface area, dye adsorption, short-circuit photocurrent density (Jsc), open circuit voltage (Voc) and the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) are significantly improved (up to 107% enhancement on PCE). Particularly, the addition of alcohol and ammonia in TiO2 sol results in more hydroxyl groups chemisorbed onto the surface of the photoanodes, which is favorable for achieving large amount of dye adsorption. The influence of sol-treating time on the microstructure, morphology of photoanodes and the corresponding photovoltaic performance of DSSCs are investigated. It is found that immersing the TNT arrays into TiO2 sol for 0.5-2 h gives PCE of DSSC higher than 9.6%, and the highest PCE of 9.86% is achieved in DSSC when treating the TNT arrays with TiO2 sol for 2 h.

  6. Improved performance of dye-sensitized solar cells using TiO2 nanotubes infiltrated by TiO2 nanoparticles using a dipping-rinsing-hydrolysis process

    NASA Astrophysics Data System (ADS)

    Lin, Lu-Yin; Chen, Chia-Yuan; Yeh, Min-Hsin; Tsai, Keng-Wei; Lee, Chuan-Pei; Vittal, R.; Wu, Chun-Guey; Ho, Kuo-Chuan

    2013-12-01

    An efficient back-illuminated dye-sensitized solar cell (DSSC) is made with a flexible Ti-foil based photoanode composed of a composite TiO2 film with TiO2 nanotubes (TNT) and TiO2 nanoparticles (TNP). The composite TiO2 film is fabricated through a novel dipping-rinsing-hydrolysis (DRH) process by inserting TiO2 into TNT and sintering the product to form TNP inside TNT. By directly placing TiO2 nanoparticles into TNT, the former grow internally from the base of TNT to occupy it completely. This solves previous problems of incomplete filling of TNP into TNT, which used partial penetration of TiCl4 reactant from the top of the TNT. In the present case, the TNP are grown from the base of TNT. A DSSC containing TNT and TNP prepared in this way shows a photoelectric efficiency of 6.45%, which is much higher than that (4.21%) of a DSSC with untreated TNT. The films are characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The improvement in the photoelectric efficiency is explained by using electrochemical impedance spectroscopy (EIS), incident photon-to-current conversion efficiency (IPCE) analysis, and UV-absorption spectra analysis.

  7. A TiO2 abundance map for the northern maria

    NASA Technical Reports Server (NTRS)

    Johnson, T. V.; Saunders, R. S.; Matson, D. L.; Mosher, J. A.

    1977-01-01

    A map of TiO2 abundance for most of the northern maria is presented. The telescopic data base used is the 0.38/0.56-micron ratio mosaic from Johnson et at. (1977). The titanium content has been estimated using the correlation established by Charette et al. (1974). The combination of observational, processing, and calibration errors indicates that the TiO2 map is accurate to + or - 2% (wt% TiO2) for high TiO2 content (more than 5%) and + or - 1% for low values of TiO2. Analysis of the lunar sample and telescopic data suggests strongly that the spectral parameter mapped is sensitive primarily to TiO2 abundance in the range 3-9% and does not correlate directly with iron content. It is suggested, however, that for the low TiO2 mare regions (less than 2-3% TiO2) there may be a relation between the spectral ratio and iron content and that some of the reddest mare areas in the Imbrium region may have low iron contents as well as low titanium abundances.

  8. Neurotoxicity and biochemical responses in the earthworm Pheretima hawayana exposed to TiO2NPs.

    PubMed

    Khalil, Abdelmonem M

    2015-12-01

    Serious concerns have been expressed about potential risks of manufactured TiO2NPs. In this research, toxicity of nanoparticulate and bulk TiO2 were examined to the earthworm Pheretima hawayana. The 24-h median lethal concentration (LC50) and sublethal endpoints were assessed. Both NPs and their bulk counterparts were toxic. The 24-h LC50 for TiO2NPs (145.36 mg kg(-1)) was highly toxic than that of bulk TiO2 (357.77 mg kg(-1)). The aim of the present work is to evaluate the suitability of P. hawayana and its biochemical responses to be used as a bioindicator organism and biomarkers of TiO2 toxicity. Earthworms were exposed to three sublethal concentrations of TiO2NPs (1, 10 and 100 µg kg(-1)) for 28 days to test acetylcholinesterase (AChE), antioxidant enzymes (superoxide dismutase: SOD and catalase: CAT) activities and MDA content. The response of the antioxidant enzymes combined with AChE inhibition and MDA accumulation indicated that TiO2NPs could induce significant impairments to the earthworms at the actual environment tested concentrations. The results pointed out the high sensitivity of the antioxidant and oxidative stress related responses to TiO2NPs exposure, demonstrating their usefulness in environmental monitoring and risk assessment. The study highlights also the usefulness of earthworm P. hawayana as potential bioindicator species for assessing the risk of nanoparticles environmental contamination.

  9. Charge Separation in TiO2/BDD Heterojunction Thin Film for Enhanced Photoelectrochemical Performance.

    PubMed

    Terashima, Chiaki; Hishinuma, Ryota; Roy, Nitish; Sugiyama, Yuki; Latthe, Sanjay S; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Fujishima, Akira

    2016-01-27

    Semiconductor photocatalysis driven by electron/hole has begun a new era in the field of solar energy conversion and storage. Here we report the fabrication and optimization of TiO2/BDD p-n heterojunction photoelectrode using p-type boron doped diamond (BDD) and n-type TiO2 which shows enhanced photoelectrochemical activity. A p-type BDD was first deposited on Si substrate by microwave plasma chemical vapor deposition (MPCVD) method and then n-type TiO2 was sputter coated on top of BDD grains for different durations. The microstructural studies reveal a uniform disposition of anatase TiO2 and its thickness can be tuned by varying the sputtering time. The formation of p-n heterojunction was confirmed through I-V measurement. A remarkable rectification property of 63773 at 5 V with very small leakage current indicates achieving a superior, uniform and precise p-n junction at TiO2 sputtering time of 90 min. This suitably formed p-n heterojunction electrode is found to show 1.6 fold higher photoelectrochemical activity than bare n-type TiO2 electrode at an applied potential of +1.5 V vs SHE. The enhanced photoelectrochemical performance of this TiO2/BDD electrode is ascribed to the injection of hole from p-type BDD to n-type TiO2, which increases carrier separation and thereby enhances the photoelectrochemical performance. PMID:26756353

  10. Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

    PubMed

    Jang, Insan; Shim, Seong-Cheol; Choi, Dong-Soon; Cha, Bong-Kuen; Lee, Jae-Kwan; Choe, Byung-Hak; Choi, Won-Youl

    2015-08-01

    To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 μm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew.

  11. Neurotoxicity and biochemical responses in the earthworm Pheretima hawayana exposed to TiO2NPs.

    PubMed

    Khalil, Abdelmonem M

    2015-12-01

    Serious concerns have been expressed about potential risks of manufactured TiO2NPs. In this research, toxicity of nanoparticulate and bulk TiO2 were examined to the earthworm Pheretima hawayana. The 24-h median lethal concentration (LC50) and sublethal endpoints were assessed. Both NPs and their bulk counterparts were toxic. The 24-h LC50 for TiO2NPs (145.36 mg kg(-1)) was highly toxic than that of bulk TiO2 (357.77 mg kg(-1)). The aim of the present work is to evaluate the suitability of P. hawayana and its biochemical responses to be used as a bioindicator organism and biomarkers of TiO2 toxicity. Earthworms were exposed to three sublethal concentrations of TiO2NPs (1, 10 and 100 µg kg(-1)) for 28 days to test acetylcholinesterase (AChE), antioxidant enzymes (superoxide dismutase: SOD and catalase: CAT) activities and MDA content. The response of the antioxidant enzymes combined with AChE inhibition and MDA accumulation indicated that TiO2NPs could induce significant impairments to the earthworms at the actual environment tested concentrations. The results pointed out the high sensitivity of the antioxidant and oxidative stress related responses to TiO2NPs exposure, demonstrating their usefulness in environmental monitoring and risk assessment. The study highlights also the usefulness of earthworm P. hawayana as potential bioindicator species for assessing the risk of nanoparticles environmental contamination. PMID:26398239

  12. Synergetic effects in novel hydrogenated F-doped TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Samsudin, Emy Marlina; Abd Hamid, Sharifah Bee; Juan, Joon Ching; Basirun, Wan Jefrey; Centi, Gabriele

    2016-05-01

    The synergistic effect between fluorine and hydrogen in hydrogenated F-doped TiO2 photocatalysts is evaluated for the photocatalytic degradation of atrazine. The interaction between fluorine and hydrogen species in hydrogenated F-doped TiO2 overcomes the limitations of individual F-doped TiO2 and hydrogenated TiO2 photocatalyst properties. Hydrogenated F-doped TiO2 is photo-active under UV, visible and infrared light illumination with efficient electrons and holes separations. The optimized concentration of surface vacancies and Ti3+ centers coupled with enhanced surface hydrophilicity facilitates the production of surface-bound and free hydroxyl radicals. The surface of the catalyst contains dbnd Tisbnd F, dbnd Tisbnd OH, dbnd Tisbnd Ovacancy and dbnd Tisbnd H bonds as evidenced by XPS, Raman, FTIR and HR-TEM analysis. This combination also triggers the formation of new Ti3+ occupied states under the conduction band of hydrogenated F-doped TiO2. Moreover, the change in the pore structure from cylindrical to slits and larger surface area facilitates surface charge interactions. The thermal stability is also enhanced and a single anatase phase is obtained. The size of the particles of hydrogenated F-doped TiO2 is also uniform with defined and homogeneous crystal structure. This synergetic effect between fluorine and hydrogen opens up new alternatives in improving the properties of TiO2 and its photocatalytic activity.

  13. Preparation and characterization of whey protein film incorporated with TiO2 nanoparticles.

    PubMed

    Zhou, J J; Wang, S Y; Gunasekaran, S

    2009-09-01

    Biodegradable titanium dioxide (TiO(2))/whey protein isolate (WPI) blend films were made by casting denatured WPI film solutions incorporated with TiO(2) nanoparticles. X-ray diffraction, UV-vis spectra, and fluorescence spectra of the films showed the successful incorporation of TiO(2) nanoparticles into the WPI matrix and indicated the interactions between TiO(2) and WPI. Mechanical tests revealed the antiplasticizing effect of TiO(2) nanoparticles on the WPI/TiO(2) film. Small amounts (<1 wt%) of added TiO(2) nanoparticles significantly increase the tensile properties of WPI film, but also decrease the moisture barrier properties. The addition of higher amounts (>1 wt%) of TiO(2) improves moisture barrier properties but lowers the tensile properties of the film. Microstructural evaluation confirmed the aggregation and distribution of TiO(2) nanoparticles within the WPI matrix and validated the results of functional properties of the WPI/TiO(2) film.

  14. Comparison of photocatalytic properties of TiO2 thin films and fibers

    NASA Astrophysics Data System (ADS)

    Ozdemir, Mehtap; Kurt, Metin; Ozyuzer, Lutfi; Aygun, Gulnur

    2016-10-01

    Efficiency of solar panels degrades as a result of organic contamination such as airborne particles, bird droppings and leaves. Any foreign object on photovoltaic panels reduces the sunlight entering the absorbing surface of the solar panels. Since this leads to a major problem decreasing in energy production, solar panels should be cleaned. The self-cleaning method can be preferred. There are some methods to clean the surface of solar panels. Among the self-cleaning materials, TiO2 is the most preferable ones because of its powerful photocatalytic properties. In this study, photocatalytic TiO2 were produced in two different nanostructures: nanofibers and thin films. TiO2 nanofibers were successfully produced by electrospinning. TiO2 thin films were fabricated by reactive magnetron sputtering technique. Both TiO2 nanofiber and thin film structures were heat-treated to form TiO2 in anatase phase at 600 °C for 2 h in air. Then, they were evaluated by SEM analyses for morphology, X-ray diffraction (XRD) analyses for phase structures, X-ray photoelectron spectroscopy (XPS) for the chemical state and atomic concentration, and UV-spectrometer for photocatalytic performance. The results indicate that photocatalytic and transmittance properties of TiO2 thin films are better than those of nanofibers. Consequently, TiO2 based thin films exhibit better performance for solar cell applications due to the surface cleanliness.

  15. Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

    PubMed

    Jang, Insan; Shim, Seong-Cheol; Choi, Dong-Soon; Cha, Bong-Kuen; Lee, Jae-Kwan; Choe, Byung-Hak; Choi, Won-Youl

    2015-08-01

    To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 μm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew. PMID:26149697

  16. Sonocatalytic removal of an organic dye using TiO2/Montmorillonite nanocomposite.

    PubMed

    Khataee, Alireza; Sheydaei, Mohsen; Hassani, Aydin; Taseidifar, Mojtaba; Karaca, Semra

    2015-01-01

    The sonocatalytic performance of the synthesized TiO2/Montmorillonite K10 (TiO2/MMT) nanocomposite was studied in removal of Basic Blue 3 (BB3) from water. The TiO2/MMT nanocomposite was prepared by hydrothermal method. Scanning electron microscope, X-ray diffraction and Fourier transform infrared were used to characterize the synthesized nanocomposite. The average size of TiO2 nanoparticles decreased from 60-80nm to 40-60nm through the immobilization of this semiconductor on the surface of MMT. The obtained results indicated that the sonocatalytic activity of TiO2/MMT nanocomposite was higher than that of pure TiO2 nanoparticles and MMT particles. Furthermore, the main influence factors on the sonocatalytic activity such as the BB3 concentration, pH of solution, TiO2/MMT dose, power of ultrasonic generator, and inorganic salts were studied. The intermediates of BB3 degradation during the sonocatalytic process in the presence of the TiO2/MMT nanocomposite have been monitored by gas chromatography-mass spectrometry. PMID:25060118

  17. Novel photocatalytic antibacterial activity of TiO2 microspheres exposing 100% reactive {111} facets.

    PubMed

    Sun, Liang; Qin, Ying; Cao, Qingqing; Hu, Bingqing; Huang, Zhiwei; Ye, Ling; Tang, Xingfu

    2011-12-21

    TiO(2) microspheres constructed by well-crystallized faceted nanorods with high aspect ratios expose 100% photocatalytic reactive {111} facets on the spherical surface. The microspheres demonstrated excellent photocatalytic antibacterial activity towards Staphylococcus aureus due to effective suppression of photoinduced electron-hole pair recombination and active TiO(2)@˙OH core-shell structure. PMID:22051605

  18. Sunlight highly photoactive Bi2WO6-TiO2 heterostructures for rhodamine B degradation.

    PubMed

    Colón, G; Murcia López, S; Hidalgo, M C; Navío, J A

    2010-07-14

    Highly efficient Bi(2)WO(6)-TiO(2) heterostructures are synthesized by means of a hydrothermal method; they have high photoactivity for the degradation of rhodamine B under sunlike irradiation. An interesting synergetic effect between TiO(2) and Bi(2)WO(6) leads to an improved charge carrier separation mechanism, causing the excellent photocatalytic performance.

  19. Enhancement in photo-induced hydrophilicity of TiO2/CNT nanostructures by applying voltage

    NASA Astrophysics Data System (ADS)

    Abdi, Yaser; Khalilian, Maryam; Arzi, Ezatollah

    2011-06-01

    Carbon nanotube (CNT) arrays were synthesized by plasma-enhanced chemical vapour deposition on a silicon substrate. Cabbage-like TiO2 nanostructures on the CNTs were produced by atmospheric-pressure chemical vapour deposition. Scanning electron microcopy was used to study the morphology of the TiO2/CNT structures while x-ray diffraction and Fourier transform infrared (FTIR) spectroscopy were used to verify the characteristics of the prepared nanostructures. Their hydrophilicity under UV and visible light was investigated and compared with the activity of thin films of TiO2. The TiO2/CNTs showed a highly improved photocatalytic activity in comparison with the TiO2 film. The excellent visible-light-induced hydrophilicity of the TiO2/CNTs was attributed to the generation of electron-hole pairs by visible light excitation with a low recombination rate. The results of this study showed that the fabricated cabbage-like TiO2/CNT nanostructures have a super-hydrophilic surface without further UV irradiation. Electrical measurements showed that a p-n junction was formed at the interface of the TiO2/CNTs. Consequently, a super-hydrophilic surface was achieved by applying an electric bias voltage. Visible-light- and electro-induced hydrophilicity of the obtained nanostructure was reported in this work.

  20. TiO2@C core-shell nanoparticles formed by polymeric nano-encapsulation

    PubMed Central

    Vasei, Mitra; Das, Paramita; Cherfouth, Hayet; Marsan, Benoît; Claverie, Jerome P.

    2014-01-01

    TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e., the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolysis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent. PMID:25072054

  1. TiO2@C Core-Shell Nanoparticles Formed by Polymeric Nano-Encapsulation

    NASA Astrophysics Data System (ADS)

    Vasei, Mitra; Das, Paramita; Cherfouh, Hayet; Marsan, Benoit; Claverie, Jerome

    2014-07-01

    TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e. the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolisis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent.

  2. TiO2@C core-shell nanoparticles formed by polymeric nano-encapsulation.

    PubMed

    Vasei, Mitra; Das, Paramita; Cherfouth, Hayet; Marsan, Benoît; Claverie, Jerome P

    2014-01-01

    TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e., the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolysis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent. PMID:25072054

  3. TiO2 hollow spheres composed of highly crystalline nanocrystals exhibit superior lithium storage properties.

    PubMed

    Zhang, Genqiang; Wu, Hao Bin; Song, Taeseup; Paik, Ungyu; Lou, Xiong Wen David

    2014-11-10

    While the synthesis of TiO2 hollow structures is well-established, in most cases it is particularly difficult to control the crystallization of TiO2 in solution or by calcination. As a result, TiO2 hollow structures do not really exhibit enhanced lithium storage properties. Herein, we report a simple and cost-effective template-assisted method to synthesize anatase TiO2 hollow spheres composed of highly crystalline nanocrystals, in which carbonaceous (C) spheres are chosen as the removable template. The release of gaseous species from the combustion of C spheres may inhibit the growth of TiO2 crystallites so that instead small TiO2 nanocrystals are generated. The small size and high crystallinity of primary TiO2 nanoparticles and the high structural integrity of the hollow spheres gives rise to significant improvements in the cycling stability and rate performance of the TiO2 hollow spheres. PMID:25124735

  4. A thermal study on the structural changes of bimetallic ZrO2-modified TiO2 nanotubes synthesized using supercritical CO2.

    PubMed

    Lucky, R A; Charpentier, P A

    2009-05-13

    In this study the thermal behavior of bimetallic ZrO(2)-TiO(2) (10/90 mol/mol) nanotubes are discussed which were synthesized via a sol-gel process in supercritical carbon dioxide (scCO(2)). The effects of calcination temperature on the morphology, phase structure, mean crystallite size, specific surface area and pore volume of the nanotubes were investigated by using a variety of physiochemical techniques. We report that SEM and TEM images showed that the nanotubular structure was preserved at up to 800 degrees C calcination temperature. When exposed to higher temperatures (900-1000 degrees C) the ZrO(2)-TiO(2) tubes deformed and the crystallites fused together, forming larger crystallites, and a bimetallic ZrTiO(4) species was detected. These results were further examined using TGA, FTIR, XRD and HRTEM analysis. The BET textural properties demonstrated that the presence of a small amount of Zr in the TiO(2) matrix inhibited the grain growth, stabilized the anatase phase and increased the thermal stability. PMID:19420640

  5. Improvement of Ultrasonic Disinfection Power Using TiO2 Photocatalyst

    NASA Astrophysics Data System (ADS)

    Dadjour, Mahmoud Farshbaf; Ogino, Chiaki; Matsumura, Susumu; Nakamura, Shinichi; Shimizu, Nobuaki

    2005-03-01

    The disinfection power of an ultrasonic system was enhanced using TiO2-photocatalyst in the irradiating solutions. Cultures of Legionella were used in the irradiation system with and without TiO2. A significant decrease in the concentration of viable cells was observed during irradiation in the presence of TiO2. The rate of cell killing was higher in the presence of TiO2 than it was with Al2O3, and was proportional to the amount of TiO2 used in the irradiating samples. There was no significant effect of cell concentration on the rate of cell killing in the range of 103 to 107 CFU/ml. Addition of OH radical scavengers such as glutathione, ascorbic acid and histidine to the irradiating solutions reduced the rate of disinfection, thus indicating the primary role of OH radicals in this process.

  6. Surface morphology of titanium dioxide (TiO2) nanoparticles on aluminum interdigitated device electrodes (IDEs)

    NASA Astrophysics Data System (ADS)

    Azizah, N.; Hashim, U.; Arshad, M. K. Md.; Gopinath, Subash C. B.; Nadzirah, Sh.; Farehanim, M. A.; Fatin, M. F.; Ruslinda, A. R.; Ayub, R. M.

    2016-07-01

    Titanium dioxide (TiO2) nanoparticles based Interdigitated Device Electrodes (IDEs) Nanobiosensor device was developed for intracellular biochemical detection. Fabrication and characterization of Scanning Electron Microscopy (SEM) using IDE nanocoated with TiO2 was studied in this paper. SEM analysis was carried out at 10 kV acceleration volatege and a 9.8 mA emission current to compare IDE with and without TiO2 on the surface area. The simple fabrication process, high sensitivity, and fast response of the TiO2 based IDEs facilitate their applications in a wide range of areas. The small size of semiconductor TiO2 based IDE for sensitive, label-free, real time detection of a wide range of biological species could be explored in vivo diagnostics and array-based screening.

  7. Surface properties and biocompatibility of nanostructured TiO2 film deposited by RF magnetron sputtering.

    PubMed

    Majeed, Asif; He, Jie; Jiao, Lingrui; Zhong, Xiaoxia; Sheng, Zhengming

    2015-01-01

    Nanostructured TiO2 films are deposited on a silicon substrate using 150-W power from the RF magnetron sputtering at working pressures of 3 to 5 Pa, with no substrate bias, and at 3 Pa with a substrate bias of -50 V. X-ray diffraction (XRD) analysis reveals that TiO2 films deposited on unbiased as well as biased substrates are all amorphous. Surface properties such as surface roughness and wettability of TiO2 films, grown in a plasma environment, under biased and unbiased substrate conditions are reported according to the said parameters of RF power and the working pressures. Primary rat osteoblasts (MC3T3-E1) cells have been cultured on nanostructured TiO2 films fabricated at different conditions of substrate bias and working pressures. The effects of roughness and hydrophilicity of nanostructured TiO2 films on cell density and cell spreading have been discussed.

  8. Dramatic activity of mixed-phase TiO2 photocatalyst synthesized by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Li, Huiquan; Xu, Bolian; Fan, Yining

    2013-02-01

    The mixed-phase TiO2 photocatalysts with different anatase/rutile/brookite ratios and high specific surface area (157-218 m2/g) were prepared by hydrothermal method at 100 °C and the effect of rutile content in TiO2 on the BET surface area, light absorption and separation efficiency of photogenerated charge carriers was studied and correlated to the photocatalytic activity of TiO2. Rutile content increased from 0% to 100% by increasing the amount of TiCl4 in aqueous phase and the initial pH value of reaction solution played an important role in the phase composition of TiO2. The photocatalytic mechanism of mixed-phase TiO2 was discussed.

  9. Highly flexible coaxial nanohybrids made from porous TiO2 nanotubes.

    PubMed

    Wang, Daoai; Liu, Ying; Wang, Chengwei; Zhou, Feng; Liu, Weimin

    2009-05-26

    Anatase TiO(2), an n-type semiconductor, has gained considerable research interest over several decades due to its photocatalytic activity. Most recently, its properties for photoelectrical conversion in solar cells has been explored. Anodized TiO(2) nanotube (NT) arrays have been developed and possess improved photocatalytic, sensing, photoelectrolystic, and photovoltaic properties. The present work describes using TiO(2) as the building block to form ordered heterojunctions via simple electrodeposition with materials of potential interest, including conducting polymers (polypyrrole, poly(3-hexylthiophene)), inorganic semiconducting materials (CdS), and metals (Ni and Au, etc.). A key finding is that the synthesized TiO(2) NT-nanowires(nanotubes) nanohybrids are highly flexible after being peeled off from mother substrates, which is in contrast to more fragile pure TiO(2) NTs. These highly flexible coaxial nanohybrids are expected to have potent applications.

  10. Electrochromic properties of spray deposited TiO 2-doped WO 3 thin films

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Mujawar, S. H.; Inamdar, A. I.; Sadale, S. B.

    2005-08-01

    TiO 2-doped WO 3 thin films were deposited onto fluorine-doped tin oxide coated conducting glass substrates using spray pyrolysis technique at 525 °C. The volume percentage of TiO 2 dopant was varied from 13% to 38%. The thin film samples were transparent, uniform and strongly adherent to the substrates. Electrochromical properties of TiO 2-doped WO 3 thin films were studied with the help of cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC) techniques. It has been found that TiO 2 doping in WO 3 enhances its electrochromic performance. Colouration efficiency becomes almost double and samples exhibit increasingly high reversibility with TiO 2 doping concentrations, in the studied range.

  11. A simple hydrothermal preparation of TiO 2 nanomaterials using concentrated hydrochloric acid

    NASA Astrophysics Data System (ADS)

    Nguyen Phan, Thuy-Duong; Pham, Hai-Dinh; Viet Cuong, Tran; Jung Kim, Eui; Kim, Sunwook; Woo Shin, Eun

    2009-12-01

    A TiO 2 nanostructure was synthesized via a simple method using only concentrated hydrochloric acid as the morphological/crystallographic controlling agent. Microscopy images showed that the texture of the TiO 2 powder could be easily engineered and tuned by tailoring the HCl volume, creating cuboid, flower, cauliflower, and ball-shaped particles. Three-dimensional TiO 2 microparticles resulted from the self-assembly of nanostructured sub-units including nanocubes, nanoprisms, and nanorods. The crystalline anatase and rutile phases were also identified depending on the acidic medium. HCl played a key role in orchestrating the structures and morphologies of the TiO 2 nanoscale materials. The phase transformation and morphological changes were strongly related to the crystal growth mechanism of the TiO 2 nanostructure.

  12. Fabrication of TiO2 Colloidal Crystal Films and Characterization of Their Photocatalytic Properties

    SciTech Connect

    Huang, Wei; Wang, Feng; Wang, Wei

    2011-01-01

    We have studied hydrolysis of organic alkyltitanate compounds and optimized reaction condition for synthesis of monodisperse titania (TiO2 colloidal particles with controlled size from nanometer to submicron. The synthesized TiO2 colloidal particles were further surface-modified with hydrophobic silane coupling agent. With the monodisperse hydrophobic particles, we fabricated TiO2 colloidal crystal thin films through transferring self-assembled colloidal crystal monolayer from water surface onto solid substrates. The TiO2 colloidal crystal films exhibit enhanced interaction with visible light. Consequently, in comparison with plain TiO2 particle thin film, the thin film with colloidal crystal structure shows enhanced photocatalytic activity, as evaluated through photodegradation of organic dye methyl orange in solution under simulated solar light.

  13. The Effect of WO 3 on the Photocatalytic Activity of TiO 2

    NASA Astrophysics Data System (ADS)

    Do, Y. R.; Lee, W.; Dwight, K.; Wold, A.

    1994-01-01

    Samples of WO 3/TiO 2 mixed oxide powders were prepared by two methods: (1) the incipient wetness impregnation of an aqueous ammonia solution of H 2WO 4 onto TiO 2 (P25), followed by heat treatment and (2) the ultrasonic nebulization and flame hydrolysis of a mixed isopropanol solution of tungsten(V) pentaethoxide and titanium(IV) tetraisopropoxide. The photocatalytic activities of TiO 2-based catalysts were evaluated by the degradation of 1,4-dichlorobenzene (DCB). The addition of WO 3 to TiO 2 greatly increased its photocatalytic behavior. This may be related to an increase in the transfer of electrons from the TiO 2 to the outer system, via the formation of an intermediate W(V) species.

  14. Enhanced adsorption of atrazine from aqueous solution by molecularly imprinted TiO2 film

    NASA Astrophysics Data System (ADS)

    Zhang, Chunjing; Yan, Jinlong; Zhang, Chunxiao; Yang, Zhengpeng

    2012-07-01

    TiO2 film imprinted by atrazine molecule at the surface of quartz crystal was prepared using molecular imprinting and surface sol-gel process. The molecularly imprinted TiO2 film was characterized by scanning electron microscopy and cyclic voltammetry, and the atrazine adsorption was investigated by quartz crystal microbalance (QCM) technique. In comparison with non-imprinted TiO2 film, the molecularly imprinted TiO2 film exhibits high selectivity for atrazine, better reversibility and a much higher adsorption capacity for the target molecule, the adsorption equilibrium constant estimated from the in situ frequency measurement is about 6.7 × 104 M-1, which is thirteen times higher than that obtained on non-imprinted TiO2 film.

  15. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Yoo, Seung Hwa; Ali, Ghafar; Cho, Sung Oh

    2010-03-01

    A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

  16. A Multiscale TiO2 Nanorod Array for Ultrasensitive Capture of Circulating Tumor Cells.

    PubMed

    Sun, Na; Li, Xinpan; Wang, Zhili; Zhang, Ruihua; Wang, Jine; Wang, Kewei; Pei, Renjun

    2016-05-25

    In this work, a uniform multiscale TiO2 nanorod array is fabricated to provide a "multi-scale interacting platform" for cell capture, which exhibits excellent capture specificity and sensitivity of the target cells after modification with bovine serum albumin (BSA) and DNA aptamer. After studying the capture performance of the BSA-aptamer TiO2 nanorod substrates and other nanostructured substrates, we can conclude that the multisacle TiO2 nanorod substrates could indeed effectively enhance the capture yields of target cancer cells. The capture yield of artificial blood samples on the BSA-aptamer TiO2 nanorod substrates is up to 85%-95%, revealing the potential application of the TiO2 nanorods on efficient and sensitive capture of rare circulating tumor cells. PMID:27176724

  17. Surface properties and biocompatibility of nanostructured TiO2 film deposited by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Majeed, Asif; He, Jie; Jiao, Lingrui; Zhong, Xiaoxia; Sheng, Zhengming

    2015-02-01

    Nanostructured TiO2 films are deposited on a silicon substrate using 150-W power from the RF magnetron sputtering at working pressures of 3 to 5 Pa, with no substrate bias, and at 3 Pa with a substrate bias of -50 V. X-ray diffraction (XRD) analysis reveals that TiO2 films deposited on unbiased as well as biased substrates are all amorphous. Surface properties such as surface roughness and wettability of TiO2 films, grown in a plasma environment, under biased and unbiased substrate conditions are reported according to the said parameters of RF power and the working pressures. Primary rat osteoblasts (MC3T3-E1) cells have been cultured on nanostructured TiO2 films fabricated at different conditions of substrate bias and working pressures. The effects of roughness and hydrophilicity of nanostructured TiO2 films on cell density and cell spreading have been discussed.

  18. [Mechanism and kinetics of phenol degradation by TiO2 photocatalytic combined technologies].

    PubMed

    Zhang, Yi; Huang, Ruo-Nan; Wang, Xiao-Min; Wang, Qi; Cong, Yan-Qing

    2013-02-01

    The combination H2O2, or electrical catalytic (EC) system with TiO2 photbcatalytic system for phenol degradation was investigated. The catalytic systems of TiO2/UV, H2O2/UV, TiO2/UV/H2O2 and TiO2/UV/EC were compared to investigate the phenol degradation mechanism and kinetic model. The degradation of phenol in TiO2/UV/H2O2 and TiO2/UV/EC system is more effective than that in TiO2/UV system. With the solution pH of 6, TiO, concentration of 0.2 g.L-1, UV illumination of 2 h, the photocatalysis removal efficiency of phenol reaches to 86%, if the current density of 12 mA.cm-2 is added, the removal efficiency of phenol could reach to 100%. The energy utilization in different catalytic systems was also compared. When phenol is degraded in 15 min, in TiO2/UV/EC system the energy utilization is the highest of 0.0306 g.(kW. h)-1 with the energy consumption of 0.0640 kW.h-1. It indicates that much more energy is used in TiO2/UV/EC system for phenol degradation. During the analysis of intermediate products in different catalysis systems, the first-order kinetic model of phenol degradation and intermediate products such as hydroquinone, catechol and benzoquinone formation were established. The kinetic model is validated the phenol degradation pathway in different catalysis systems, and also indicates the TiO2/UV/EC system could enhance phenol and intermediate products degradation.

  19. Comparing multistep immobilized metal affinity chromatography and multistep TiO2 methods for phosphopeptide enrichment.

    PubMed

    Yue, Xiaoshan; Schunter, Alissa; Hummon, Amanda B

    2015-09-01

    Phosphopeptide enrichment from complicated peptide mixtures is an essential step for mass spectrometry-based phosphoproteomic studies to reduce sample complexity and ionization suppression effects. Typical methods for enriching phosphopeptides include immobilized metal affinity chromatography (IMAC) or titanium dioxide (TiO2) beads, which have selective affinity and can interact with phosphopeptides. In this study, the IMAC enrichment method was compared with the TiO2 enrichment method, using a multistep enrichment strategy from whole cell lysate, to evaluate their abilities to enrich for different types of phosphopeptides. The peptide-to-beads ratios were optimized for both IMAC and TiO2 beads. Both IMAC and TiO2 enrichments were performed for three rounds to enable the maximum extraction of phosphopeptides from the whole cell lysates. The phosphopeptides that are unique to IMAC enrichment, unique to TiO2 enrichment, and identified with both IMAC and TiO2 enrichment were analyzed for their characteristics. Both IMAC and TiO2 enriched similar amounts of phosphopeptides with comparable enrichment efficiency. However, phosphopeptides that are unique to IMAC enrichment showed a higher percentage of multiphosphopeptides as well as a higher percentage of longer, basic, and hydrophilic phosphopeptides. Also, the IMAC and TiO2 procedures clearly enriched phosphopeptides with different motifs. Finally, further enriching with two rounds of TiO2 from the supernatant after IMAC enrichment or further enriching with two rounds of IMAC from the supernatant TiO2 enrichment does not fully recover the phosphopeptides that are not identified with the corresponding multistep enrichment. PMID:26237447

  20. Characteristics of ionic polymer-metal composite with chemically doped TiO2 particles

    NASA Astrophysics Data System (ADS)

    Jung, Youngsoo; Kim, Seong Jun; Kim, Kwang J.; Lee, Deuk Yong

    2011-12-01

    Many studies have investigated techniques to improve the bending performance of ionic polymer-metal composite (IPMC) actuators, including 'doping' of metal particles in the polymer membrane usually by means of physical processes. This study is mainly focused on the characterization of the physical, electrochemical and electromechanical properties of TiO2-doped ionic polymer membranes and IPMCs prepared by the sol-gel method, which results in a uniform distribution of the particles inside the polymer membrane. X-ray and UV-visible spectra indicate the presence of anatase-TiO2 in the modified membranes. TiO2-doped membranes (0.16 wt%) exhibit the highest level of water uptake. The glass transition temperature of these membranes, measured using differential scanning calorimetry (DSC), increases with the increase of the amount of TiO2 in the membrane. Dynamic mechanical analysis (DMA) demonstrated that the storage modulus of dried TiO2-doped ionic polymer membranes increases as the amount of TiO2 in the membrane increases, whereas the storage modulus of hydrated samples is closely related to the level of water uptake. Electrochemical impedance spectroscopy (EIS) shows that the conductivity of TiO2-doped membranes decreases with increasing TiO2 content in spite of an internal resistance drop in the samples. Above all, bending deflection of TiO2-doped IPMC decreased with higher TiO2 content in the membrane while the blocking force of each sample increased with the higher TiO2 content. Additionally, it was determined that the lifetime of IPMC is strongly dependent on the level of water uptake.

  1. Characterization and comparison of photocatalytic activities of prepared TiO2/graphene nanocomposites using titanium butoxide and TiO2 via microwave irradiation method

    NASA Astrophysics Data System (ADS)

    Darvishi, Motahareh; Seyed-Yazdi, Jamileh

    2016-08-01

    Photocatalysis based on TiO2 nanostructures with nanoscale hybridization of graphene, is a promising method to create highly conductive composite materials and surfaces with enhanced light absorption. In this study, graphite-oxide (GO) was produced by improved Hummers’ method followed by synthesis of TiO2/graphene nanocomposites. We used two precursors, titanium butoxide (TBO) and commercial TiO2, to produce nanocomposites in a mixture of water/ethanol and graphene-oxide, for hydrolysis of titania precursors on graphene-oxide sheets resulting in the formation of nanocomposites. Microwave irradiation is used to reduce graphene-oxide into graphene. TiO2/graphene nanocomposites in both cases demonstrate enhancement of overall photocatalytic activity compared with titania precursors which was examined by degradation of methylene blue (MB). In this study, nanocomposites were synthesized with different mass ratios of GO compare to titania precursors (i.e. GO: 1, 5 and 8 wt%). Photocatalytic performance increased with the increasing content of graphene in both cases. The reduction rate of MB for TiO2 was 62% and for TiO2/graphene (TiO2/G) (GO: 8 wt%) was 85% after 90 min, and for TBO and TBO/G (GO: 8 wt%) was 3% and 99.95%, respectively. SEM, XRD, Fourier transform infrared and UV–vis spectroscopy were used to characterize the synthesized nanocomposites. FTIR analysis demonstrates the formation of Ti–O–C bonds and confirms the formation of nanocomposites made of graphene and titania nanoparticles.

  2. Characterization and comparison of photocatalytic activities of prepared TiO2/graphene nanocomposites using titanium butoxide and TiO2 via microwave irradiation method

    NASA Astrophysics Data System (ADS)

    Darvishi, Motahareh; Seyed-Yazdi, Jamileh

    2016-08-01

    Photocatalysis based on TiO2 nanostructures with nanoscale hybridization of graphene, is a promising method to create highly conductive composite materials and surfaces with enhanced light absorption. In this study, graphite-oxide (GO) was produced by improved Hummers’ method followed by synthesis of TiO2/graphene nanocomposites. We used two precursors, titanium butoxide (TBO) and commercial TiO2, to produce nanocomposites in a mixture of water/ethanol and graphene-oxide, for hydrolysis of titania precursors on graphene-oxide sheets resulting in the formation of nanocomposites. Microwave irradiation is used to reduce graphene-oxide into graphene. TiO2/graphene nanocomposites in both cases demonstrate enhancement of overall photocatalytic activity compared with titania precursors which was examined by degradation of methylene blue (MB). In this study, nanocomposites were synthesized with different mass ratios of GO compare to titania precursors (i.e. GO: 1, 5 and 8 wt%). Photocatalytic performance increased with the increasing content of graphene in both cases. The reduction rate of MB for TiO2 was 62% and for TiO2/graphene (TiO2/G) (GO: 8 wt%) was 85% after 90 min, and for TBO and TBO/G (GO: 8 wt%) was 3% and 99.95%, respectively. SEM, XRD, Fourier transform infrared and UV-vis spectroscopy were used to characterize the synthesized nanocomposites. FTIR analysis demonstrates the formation of Ti-O-C bonds and confirms the formation of nanocomposites made of graphene and titania nanoparticles.

  3. Synthesis, characterization and photocatalytic activity of fluorine doped TiO2 nanoflakes synthesized using solid state reaction method.

    PubMed

    Umadevi, M; Parimaladevi, R; Sangari, M

    2014-01-01

    Fluorine doped TiO2 were synthesized by solid state reaction method. Optical and structural properties of fluorine doped TiO2 were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, UV-vis diffusion reflectance spectroscopy and scanning electron microscopic techniques. The prepared fluorine doped TiO2 was smaller in size with respect to pure TiO2 and it is tetragonal in crystalline structure. Nanoflakes like structure of pure and fluorine doped TiO2 was confirmed from SEM image. Fluorine doped TiO2 shows smaller band gap, high strain and dislocation density when compared to pure TiO2. It also has higher photocatalytic activity with respect to pure TiO2.

  4. First-principles calculations of high-pressure phase transition of TiO2 during decompression: From baddeleyite-type TiO2 to α-PbO2-type TiO2

    NASA Astrophysics Data System (ADS)

    Murata, Hidenobu; Taniguchi, Takashi; Tanaka, Isao

    2016-10-01

    First-principles calculations were used to investigate the phase transition from baddeleyite-type to α-PbO2-type TiO2 during decompression. An intermediate structure was found, and its space group is Pbc21, which is polarized along [001]. The phase transition was mainly caused by oxygen diffusion, which has low activation energy for the phase transition. The activation energy increased as the pressure decreased. These results suggest that rapid decompression and preventing oxygen diffusion would be an effective way of recovering baddeleyite-type TiO2.

  5. XAS study of TiO2-based nanomaterials

    NASA Astrophysics Data System (ADS)

    Schneider, K.; Zajac, D.; Sikora, M.; Kapusta, Cz.; Michalow-Mauke, K.; Graule, Th.; Rekas, M.

    2015-07-01

    X-Ray Absorption Spectroscopy studies of the W (0-1 at% W) and Mo-doped TiO2 (0-1 at% Mo) nanoparticle specimens at the K edges of titanium and molybdenum as well as at the L2 L3 edges of tungsten are presented. The materials were prepared with Flame Spray Synthesis process by oxidation of metal-organic precursors. The Ti:K edge spectra in the XANES range show pre-edge and post-edge features characteristic for anatase. A decrease of the amplitude of the EXAFS function with doping is observed and attributed to a softening of the crystal lattice. The Mo EXAFS functions show a considerable decrease of the second-neighbour-shell peak with increasing Mo content, which is attributed to an increased number of cation vacancies. For tungsten a less pronounced effect is observed. The Mo and W XANES spectra do not show noticeable changes with doping level, which indicates their unchanged oxidation states.

  6. [Background irradiated photocatalysis of TiO2 thin films].

    PubMed

    Cen, Ji-wen; Li, Xin-jun; Liang, Yuan-yuan; He, Ming-xing; Zheng, Shao-jian; Feng, Man-zhi

    2005-05-01

    In terms of the UV irradiating directions, photocatalysis with TiO2 thin films can be divided into two types, the background irradiated photocatalysis and the foreground irradiated one. Comparatively, background irradiated photocatalysis has an advantage of avoiding the UV light attenuation which foreground irradiated one suffers when the light is going through the solution. In this article, the influence of the thickness of the films, the wavelength of light source and non-uninformly doping with V on the photocatalytic efficiency of the catalyst in case of background irradiated photocatalysis is investigated, and simultaneously it is compared with foreground irradiated one. The results show that in case of background irradiated photocatalysis there is an optimal thickness of the film according to the wavelength of the light source that is limited in the range of 300 nm to 388 nm, which is quite different from foreground irradiated one. But in both cases, the catalyst's photocatalytic activities are improved by non-uniformly doped with V.

  7. Coupled cluster calculations on TiO2 nanoclusters

    SciTech Connect

    Berardo, Enrico; Hu, Hanshi; Kowalski, Karol; Zwijnenburg, Martijn A.

    2013-08-14

    The excitation energies of the four lowest-lying singlet excited states of the TiO2 Ti2O4 and Ti3O6 clusters are calculated by a variety of different Equation-of-Motion Coupled Cluster (EOM-CC) approaches in order to obtain benchmark values for the optical excitations of titanium dioxide clusters. More specifically we investigate what is the effect of the inclusion of triple excitations "triples" in the (EOM-)CC scheme on the calculated excited states of those clusters. While for the monomer and dimer the inclusion of triples causes only a rigid shift in the excitation energies, in the case of the trimer the crossing of the interested states is observed. Coupled cluster approaches where triples are treated perturbatively were found to offer no advantage over EOM-CCSD, whereas the active-space methods (EOM-CCSDt(II/I)) proved to yield results very close to the full EOM-CCSDT, but at a much lower computational cost.

  8. A general templated method to homogeneous and composition-tunable hybrid TiO2 nanocomposite fibers.

    PubMed

    Xu, Ximing; Li, Xiaona; Lin, Pingyong; Chen, Ting; Yuan, Rusheng; Ding, Zhengxin; Wu, Ling; Wang, Xuxu; Li, Zhaohui

    2011-03-01

    Sequential impregnations of metal ions and titanium tetraisopropoxide (TTIP) into activated carbon fibers (ACF) followed by a solvothermal treatment has been found to be a general method in the preparations of homogeneous and composition-tunable hybrid TiO(2) hierarchical nanocomposite fibers like WO(3)/TiO(2), Fe(2)O(3)/TiO(2) and SnO(2)/TiO(2). PMID:21225065

  9. Graphene Oxide Modified TiO2 Micro Whiskers and Their Photo Electrochemical Performance.

    PubMed

    Rambabu, Y; Jaiswal, Manu; Roy, Somnath C

    2016-05-01

    Harnessing the solar energy and producing clean fuel hydrogen through efficient photo-electrochemical water splitting has remained one of the most challenging endeavors in materials science. The core problem is to develop a suitable photo-catalyst material that absorbs a significant part of the solar spectrum and produces electron-hole pairs that can be easily separated without recombination. In the recent times, the composite of Titanium dioxide with graphene have been investigated to explore the advantages of both class of materials. Here we report on the photo-electrochemical properties of reduced graphene oxide functionalised TiO2 whiskers. The TiO2 whiskers are obtained from potassium titanium oxide (KTi8O16) synthesized through hydrothermal technique followed by ion exchange method and heat treatment. Graphene oxide was deposited on the as prepared TiO2 whiskers using hydrothermal method. As formed samples were characterized by Raman spectroscopy to confirm the presence of reduced graphene oxide (RGO) attached to TiO2 whiskers. Comparative photo electrochemical studies were carried out for TiO2 and reduced graphene oxide modified TiO2 whiskers. Among these, RGO modified TiO2 whiskers show significantly higher photo current density possibly due to enhancement in charge separation ability and longer electron life times. PMID:27483830

  10. Visible-light responsive dye-modified TiO 2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Jiang, Dong; Xu, Yao; Wu, Dong; Sun, Yuhan

    2008-03-01

    A series of dye-modified TiO 2 photocatalysts were synthesized using dye Chrysoidine G (CG), tolylene-2,4-diisocyanate (TDI), and commercial TiO 2 (Degussa P25) as starting materials. TDI was used as a bridging molecule whose two -NCO groups reacted with Ti-OH of TiO 2 and -NH 2 groups of CG, respectively. As a result, special organic complexes were formed on the TiO 2 surface via stable π-conjugated chemical bonds between TiO 2 and dye molecules, confirmed by FT-IR, XPS, and UV-vis spectra. Due to the existence of π-conjugated surface organic complexes, the as-synthesized photocatalysts showed a great improvement in visible absorption (400-550 nm). Methylene blue, as a photodegradation target, was used to evaluate the photocatalytic performance, and the dye-modified TiO 2 exhibited much better activity under the visible light irradiation than bare TiO 2.

  11. Electrospinning Synthesis and Photocatalytic Activity of Mesoporous TiO2 Nanofibers

    PubMed Central

    Li, Jing; Qiao, Hui; Du, Yuanzhi; Chen, Chen; Li, Xiaolin; Cui, Jing; Kumar, Dnt; Wei, Qufu

    2012-01-01

    Titanium dioxide (TiO2) nanofibers in the anatase structure were successfully prepared via electrospinning technique followed by calcination process. The morphologies, crystal structure, surface area, and the photocatalytic activity of resulting TiO2 nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen sorption, and UV-vis spectroscopy. The results revealed that calcination temperature had greatly influenced the morphologies of TiO2 nanofibers, but no obvious effect was noticed on the crystal structure of TiO2 nanofibers. The photocatalytic properties of TiO2 nanofibers were evaluated by photocatalytic degradation of rhodamine B (RhB) in water under visible light irradiation. It was observed that TiO2 nanofibers obtained by calcination at 500°C for 3 hours exhibited the most excellent photocatalytic activity. We present a novel and simple method to fabricate TiO2 nanofibers with high-photocatalytic activity. PMID:22619598

  12. Water-dispersible TiO2 nanoparticles via a biphasic solvothermal reaction method

    NASA Astrophysics Data System (ADS)

    Mohan, Rajneesh; Drbohlavova, Jana; Hubalek, Jaromir

    2013-12-01

    A biphasic solvothermal reaction method has been used for the synthesis of TiO2 nanoparticles (NPs). In this method, hydrolysis and nucleation occur at the interface of organic phase (titanium (IV) n-propoxide and stearic acid dissolved in toluene) and water phase ( tert-butylamine dissolved in water) resulting in the nucleation of the stearic acid-capped TiO2 NPs. These NPs are hydrophilic due to hydrophobic stearic acid ligands and could be dispersed in toluene, but not in water. These stearic acid-capped TiO2 NPs were surface-modified with 2,3-dimercaptosuccinic acid (DMSA) in order to make them water soluble. The resultant TiO2 NPs were easily redispersed in water without any noticeable aggregation. The Rietveld profile fitting of X-ray diffraction (XRD) pattern of the TiO2 NPs revealed highly crystalline anatase structure. The average crystallite size of TiO2 NPs was calculated to be 6.89 nm, which agrees with TEM results. These results have important implications for the use of TiO2 in biomedical, environmental, and industrial applications.

  13. Self-cleaning and superhydrophilic wool by TiO2/SiO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Pakdel, Esfandiar; Daoud, Walid A.; Wang, Xungai

    2013-06-01

    Wool fabrics were functionalised using TiO2 and TiO2/SiO2 nanocomposites through a low-temperature sol-gel method. Titanium terta isopropoxide (TTIP) and tetra ethylorthosilicate (TEOS) were employed as precursors of TiO2 and SiO2, respectively. Nanocomposite sols were devised based on three molar ratio percentages of TiO2/SiO2 70:30, 50:50, and 30:70 to investigate the role of each component. The self-cleaning and hydrophilicity of wool fabrics were analysed based on the removal of coffee stain under UV and water droplet contact angle measurements, respectively. It was observed that applying TiO2/SiO2 50:50 and 30:70 sols to wool rendered the fabric superhydrophilic. Fabrics functionalised with TiO2/SiO2 30:70 showed the highest efficiency in stain removal, followed by samples functionalised with TiO2/SiO2 50:50.

  14. Enhanced photocatalytic activity of supported TiO2 by selective surface modification of zeolite Y

    NASA Astrophysics Data System (ADS)

    Guesh, Kiros; Márquez-Álvarez, Carlos; Chebude, Yonas; Díaz, Isabel

    2016-08-01

    Zeolite Y was treated using ammonium acetate and ammonium fluoride sequentially. As a consequence the aluminum from the surface was selectively removed. Then, loading with TiO2 (20 wt%) led to a final photocatalyst. The samples were characterized by X-ray diffraction (XRD), elemental analysis (ICP-OES), N2 adsorption, diffuse reflectance UV-vis spectroscopy (DRS), photoluminescence spectroscopy (PL), and X-ray photoelectron spectroscopy (XPS). It was found that 50% of the Al atoms were removed from the surface of the zeolite without affecting the framework structure. The TiO2/treated zeolite sample yielded 92% photocatalytic degradation of 10 ppm methyl orange (MO), a model pollutant, while the TiO2/parent zeolite converted only 7.6%. The mass normalized turnover rate (TORm) of the treated zeolite loaded with TiO2 was about 12 times higher than that of the parent zeolite loaded with the same amount of TiO2 precursor. This higher photocatalytic activity of the TiO2 supported on treated zeolite can be attributed to a more efficient interaction of the TiO2 with the zeolite leading to higher adsorption capacity. Reusability of the photocatalysts was assessed by performing three consecutive reaction cycles that showed no significant loss of photocatalytic activity.

  15. Inverted polymer solar cells with employing of electrochemical-anodizing synthesized TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Mehdi, Ahmadi; Sajjad Rashidi, Dafeh; Hamed, Fatehy

    2016-04-01

    An inverted structure of polymer solar cells based on Poly(3-hexylthiophene)(P3HT):[6-6] Phenyl-(6) butyric acid methyl ester (PCBM) with using thin films of TiO2 nanotubes and nanoparticles as an efficient cathode buffer layer is developed. A total of three cells employing TiO2 thin films with different thickness values are fabricated. Two cells use layers of TiO2 nanotubes prepared via self-organized electrochemical-anodizing leading to thickness values of 203 and 423.7 nm, while the other cell uses only a simple sol-gel synthesized TiO2 thin film of nanoparticles with a thickness of 100 nm as electron transport layer. Experimental results demonstrate that TiO2 nanotubes with these thickness values are inefficient as the power conversion efficiency of the cell using 100-nm TiO2 thin film is 1.55%, which is more than the best power conversion efficiency of other cells. This can be a result of the weakness of the electrochemical anodizing method to grow nanotubes with lower thickness values. In fact as the TiO2 nanotubes grow in length the series resistance (R s) between the active polymer layer and electron transport layer increases, meanwhile the fill factor of cells falls dramatically which finally downgrades the power conversion efficiency of the cells as the fill factor falls.

  16. Fullerene C70 decorated TiO2 nanowires for visible-light-responsive photocatalyst

    NASA Astrophysics Data System (ADS)

    Cho, Er-Chieh; Ciou, Jing-Hao; Zheng, Jia-Huei; Pan, Job; Hsiao, Yu-Sheng; Lee, Kuen-Chan; Huang, Jen-Hsien

    2015-11-01

    In this study, we have synthesized C60 and C70-modified TiO2 nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C60 and C70 derivatives) can act as sinks for photogenerated electrons in TiO2, while the fullerene/TiO2 is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO2 NWs, the modified TiO2 NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO2 which expand the utilization of solar light from UV to visible light. The results reveal that the C70/TiO2 NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO2, the electron only devices and photoelectrochemical cells based on fullerenes/TiO2 are also fabricated and evaluated.

  17. Simplified TiO2 force fields for studies of its interaction with biomolecules

    NASA Astrophysics Data System (ADS)

    Luan, Binquan; Huynh, Tien; Zhou, Ruhong

    2015-06-01

    Engineered TiO2 nanoparticles have been routinely applied in nanotechnology, as well as in cosmetics and food industries. Despite active experimental studies intended to clarify TiO2's biological effects, including potential toxicity, the relation between experimentally inferred nanotoxicity and industry standards for safely applying nanoparticles remains somewhat ambiguous with justified concerns. Supplemental to experiments, molecular dynamics simulations have proven to be efficacious in investigating the molecular mechanism of a biological process occurring at nanoscale. In this article, to facilitate the nanotoxicity and nanomedicine research related to this important metal oxide, we provide a simplified force field, based on the original Matsui-Akaogi force field but compatible to the Lennard-Jones potentials normally used in modeling biomolecules, for simulating TiO2 nanoparticles interacting with biomolecules. The force field parameters were tested in simulating the bulk structure of TiO2, TiO2 nanoparticle-water interaction, as well as the adsorption of proteins on the TiO2 nanoparticle. We demonstrate that these simulation results are consistent with experimental data/observations. We expect that simulations will help to better understand the interaction between TiO2 and molecules.

  18. Fast diffusion of silver in TiO2 nanotube arrays.

    PubMed

    Zhang, Wanggang; Liu, Yiming; Zhou, Diaoyu; Wang, Hui; Liang, Wei; Yang, Fuqian

    2016-01-01

    Using magnetron sputtering and heat treatment, Ag@TiO2 nanotubes are prepared. The effects of heat-treatment temperature and heating time on the evolution of Ag nanofilms on the surface of TiO2 nanotubes and microstructure of Ag nanofilms are investigated by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Ag atoms migrate mainly on the outmost surface of the TiO2 nanotubes, and fast diffusion of Ag atoms is observed. The diffusivity for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes at 400 °C is 6.87 × 10(-18) m(2)/s, which is three orders of magnitude larger than the diffusivities for the diffusion of Ag through amorphous TiO2 films. The activation energy for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes in the temperature range of 300 to 500 °C is 157 kJ/mol, which is less than that for the lattice diffusion of Ag and larger than that for the grain boundary diffusion. The diffusion of Ag atoms leads to the formation of Ag nanocrystals on the outmost surface of TiO2 nanotubes. Probably there are hardly any Ag nanocrystals formed inside the TiO2 nanotubes through the migration of Ag. PMID:27547630

  19. Controllable atomic layer deposition of one-dimensional nanotubular TiO2

    NASA Astrophysics Data System (ADS)

    Meng, Xiangbo; Banis, Mohammad Norouzi; Geng, Dongsheng; Li, Xifei; Zhang, Yong; Li, Ruying; Abou-Rachid, Hakima; Sun, Xueliang

    2013-02-01

    This study aimed at synthesizing one-dimensional (1D) nanostructures of TiO2 using atomic layer deposition (ALD) on anodic aluminum oxide (AAO) templates and carbon nanotubes (CNTs). The precursors used are titanium tetraisopropoxide (TTIP, Ti(OCH(CH3)2)4) and deionized water. It was found that the morphologies and structural phases of as-deposited TiO2 are controllable through adjusting cycling numbers of ALD and growth temperatures. Commonly, a low temperature (150 °C) produced amorphous TiO2 while a high temperature (250 °C) led to crystalline anatase TiO2 on both AAO and CNTs. In addition, it was revealed that the deposition of TiO2 is also subject to the influences of the applied substrates. The work well demonstrated that ALD is a precise route to synthesize 1D nanostructures of TiO2. The resultant nanostructured TiO2 can be important candidates in many applications, such as water splitting, solar cells, lithium-ion batteries, and gas sensors.

  20. Heterostructured TiO2 Nanorod@Nanobowl Arrays for Efficient Photoelectrochemical Water Splitting.

    PubMed

    Wang, Wenhui; Dong, Jingya; Ye, Xiaozhou; Li, Yang; Ma, Yurong; Qi, Limin

    2016-03-01

    Heterostructured TiO2 nanorod@nanobowl (NR@NB) arrays consisting of rutile TiO2 nanorods grown on the inner surface of arrayed anatase TiO2 nanobowls are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The unique heterostructures with a hierarchical architecture are readily fabricated by interfacial nanosphere lithography followed by hydrothermal growth. Owing to the two-dimensionally arrayed structure of anatase nanobowls and the nearly radial alignment of rutile nanorods, the TiO2 NR@NB arrays provide multiple scattering centers and hence exhibit an enhanced light harvesting ability. Meanwhile, the large surface area of the NR@NB arrays enhances the contact with the electrolyte while the nanorods offer direct pathways for fast electron transfer. Moreover, the rutile/anatase phase junction in the NR@NB heterostructure improves charge separation because of the facilitated electron transfer. Accordingly, the PEC measurements of the TiO2 NR@NB arrays on the fluoride-doped tin oxide (FTO) substrate show significantly enhanced photocatalytic properties for water splitting. Under AM1.5G solar light irradiation, the unmodified TiO2 NR@NB array photoelectrode yields a photocurrent density of 1.24 mA cm(-2) at 1.23 V with respect to the reversible hydrogen electrode, which is almost two times higher than that of the TiO2 nanorods grown directly on the FTO substrate. PMID:26779803

  1. Graphene Oxide Modified TiO2 Micro Whiskers and Their Photo Electrochemical Performance.

    PubMed

    Rambabu, Y; Jaiswal, Manu; Roy, Somnath C

    2016-05-01

    Harnessing the solar energy and producing clean fuel hydrogen through efficient photo-electrochemical water splitting has remained one of the most challenging endeavors in materials science. The core problem is to develop a suitable photo-catalyst material that absorbs a significant part of the solar spectrum and produces electron-hole pairs that can be easily separated without recombination. In the recent times, the composite of Titanium dioxide with graphene have been investigated to explore the advantages of both class of materials. Here we report on the photo-electrochemical properties of reduced graphene oxide functionalised TiO2 whiskers. The TiO2 whiskers are obtained from potassium titanium oxide (KTi8O16) synthesized through hydrothermal technique followed by ion exchange method and heat treatment. Graphene oxide was deposited on the as prepared TiO2 whiskers using hydrothermal method. As formed samples were characterized by Raman spectroscopy to confirm the presence of reduced graphene oxide (RGO) attached to TiO2 whiskers. Comparative photo electrochemical studies were carried out for TiO2 and reduced graphene oxide modified TiO2 whiskers. Among these, RGO modified TiO2 whiskers show significantly higher photo current density possibly due to enhancement in charge separation ability and longer electron life times.

  2. Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity.

    PubMed

    Wu, Xiaofeng; Fang, Shun; Zheng, Yang; Sun, Jie; Lv, Kangle

    2016-02-01

    Semiconductor TiO2 photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH4N2S) modified anatase TiO2 nanorods were fabricated by calcination of the mixture of TiO2 nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO2 nanorods. With increasing the weight ratio of thiourea to TiO2 (R) from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO2 nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B) and Rhodamine B (RhB) dyes under visible light irradiation (λ > 420 nm). The increased visible-light photocatalytic activity of the prepared N-doped TiO2 nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

  3. N-doped TiO2 Prepared by RF DBD Plasma

    NASA Astrophysics Data System (ADS)

    Sun, Zhi-Guang; Liu, Jing-Lin; Li, Xiao-Song; Zhai, Zhao-Jun; Zhu, Ai-Min; Laboratory of Plasma Physical Chemistry Team

    2014-10-01

    TiO2 is the most promising photocatalyst because of its chemical stable, nontoxic, low cost, high photocatalytic activity and other attractive properties. Anatase has the highest photocatalytic activity among the three crystal form of TiO2. However, the 3.2 eV bandgap of anatase TiO2 makes it can only utilize the ultraviolet part of solar spectrum. Nitrogen doping is an effective method to extend the absorption range of anatase to visible light. N-doped TiO2 preparation methods, such as heat treatment under NH3 flow, the hydrolytic precipitation and the sol-gel process, have been reported. In this work, preparation of N-doped TiO2 was explored by radio-frequency (RF) dielectric barrier discharge (DBD) plasma using Ar as discharge gas. TiCl4, O2 and N2 were used as Ti, O and N precursors, respectively. In addition, H2 was added to the plasma. X-ray photoelectron spectra (XPS) showed nitrogen was successfully doped into the as-prepared TiO2. Further investigations on structure, composition and optical property of the as-prepared TiO2 samples were conducted by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and UV-Vis absorption spectra techniques.

  4. Fast diffusion of silver in TiO2 nanotube arrays

    PubMed Central

    Zhang, Wanggang; Liu, Yiming; Zhou, Diaoyu; Wang, Hui

    2016-01-01

    Summary Using magnetron sputtering and heat treatment, Ag@TiO2 nanotubes are prepared. The effects of heat-treatment temperature and heating time on the evolution of Ag nanofilms on the surface of TiO2 nanotubes and microstructure of Ag nanofilms are investigated by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Ag atoms migrate mainly on the outmost surface of the TiO2 nanotubes, and fast diffusion of Ag atoms is observed. The diffusivity for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes at 400 °C is 6.87 × 10−18 m2/s, which is three orders of magnitude larger than the diffusivities for the diffusion of Ag through amorphous TiO2 films. The activation energy for the diffusion of Ag atoms on the outmost surface of the TiO2 nanotubes in the temperature range of 300 to 500 °C is 157 kJ/mol, which is less than that for the lattice diffusion of Ag and larger than that for the grain boundary diffusion. The diffusion of Ag atoms leads to the formation of Ag nanocrystals on the outmost surface of TiO2 nanotubes. Probably there are hardly any Ag nanocrystals formed inside the TiO2 nanotubes through the migration of Ag. PMID:27547630

  5. Hydrogenated Anatase TiO2 as Lithium-Ion Battery Anode: Size-Reactivity Correlation.

    PubMed

    Zheng, Jing; Liu, Lei; Ji, Guangbin; Yang, Qifan; Zheng, Lirong; Zhang, Jing

    2016-08-10

    An improved hydrogenation strategy for controllable synthesis of oxygen-deficient anatase TiO2 (H-TiO2) is performed via adjusting the particle size of starting rectangular anatase TiO2 nanosheets from 90 to 30 nm. The morphology and structure characterizations obviously demonstrate that the starting materials of TiO2 nanosheets are transformed into nanoparticles with distinct size reduction; meanwhile, the concentration of oxygen vacancy is gradually increased with the decreasing particle size of starting TiO2. As a result, the Li-storage performance of H-TiO2 is not only much better than that of the pure TiO2 but also elevated stage by stage with the decreasing particle size of starting TiO2; especially the H-TiO2 with highest concentration of oxygen vacancy from smallest TiO2 nanosheets shows the best Li-storage performance with a stable discharge capacity 266 mAh g(-1) after 100 cycles at 1 C. Such excellent performance should be attributed to the joint action from oxygen vacancy and size effect, which promises significant enhancement of high electronic conductivity without weakening Li(+) diffusion via hydrogenation strategy. PMID:27434151

  6. Nanostructured TiO2 Films Attached CdSe QDs Toward Enhanced Photoelectrochemical Performance.

    PubMed

    Du, Yingying; Yang, Ping; Liu, Yunshi; Zhao, Jie; He, Haiyan; Miao, Yanping

    2016-06-01

    TiO2 films consisted of small nanoparticles were fabricated via a spinning coating method on fluorine doped in tin oxide (FTO) slide glass. After calcination, the films were subsequently sensitized by CdSe quantum dots (QDs) using mercaptopropionic acid (MPA) as a bifunctional surface modifier. Upon UV light irradiation, CdSe QDs inject electrons into TiO2 nanoparticles, thus resulting in the generation of photocurrent in QD-sensitized solar cell. The results indicate that TiO2 films sensitized by CdSe QDs have achieved 1.5-fold enhancement in photocurrent compared with pure TiO2 films, indicating that CdSe QDs can improve the photocurrent by promoting the separation of photoinduced charge carriers. In addition, the photocurrent enhances as the thickness of TiO2 films increased. Such improved photoelectrochemical performance is ascribed to the basis of improved interfacial charge transport of the TiO2-CdSe composite films. Combining QDs on TiO2 thin films is a promising and effective way to enhance the photoelectrochemical performance, which is important in QD-sensitized solar cell application. PMID:27427714

  7. Size of TiO(2) nanoparticles influences their phototoxicity: an in vitro investigation.

    PubMed

    Xiong, Sijing; George, Saji; Ji, Zhaoxia; Lin, Sijie; Yu, Haiyang; Damoiseaux, Robert; France, Bryan; Ng, Kee Woei; Loo, Say Chye Joachim

    2013-01-01

    To uncover the size influence of TiO(2) nanoparticles on their potential toxicity, the cytotoxicity of different-sized TiO(2) nanoparticles with and without photoactivation was tested. It was demonstrated that without photoactivation, TiO(2) nanoparticles were inert up to 100 μg/ml. On the contrary, with photoactivation, the toxicity of TiO(2) nanoparticles significantly increased, which correlated well with the specific surface area of the particles. Our results also suggest that the generation of hydroxyl radicals and reactive oxygen species (ROS)-mediated damage to the surface-adsorbed biomolecules could be the two major reasons for the cytotoxicity of TiO(2) nanoparticles after photoactivation. Higher ROS generation from smaller particles was detected under both biotic and abiotic conditions. Smaller particles could adsorb more proteins, which was confirmed by thermogravimetric analysis. To further investigate the influence of the generation of hydroxyl radicals and adsorption of protein, poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan were used to coat TiO(2) nanoparticles. The results confirmed that surface coating of TiO(2) nanoparticles could reduce such toxicity after photoactivation, by hindering adsorption of biomolecules and generation of hydroxyl radical (·OH) during photoactivation.

  8. Rubber sheet strewn with TiO2 particles: photocatalytic activity and recyclability.

    PubMed

    Sriwong, Chaval; Wongnawa, Sumpun; Patarapaiboolchai, Orasa

    2012-01-01

    A new method for the preparation of rubber sheet strewn with titanium dioxide particles (TiO2-strewn sheet) is presented. This simple and low cost method is based on the use of TiO2 powder (Degussa P25) being strewn onto the sheet made from rubber latex (60% HA) through a steel sieve. The characteristic of the TiO2-strewn sheet was studied by using scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) and X-ray diffractometer (XRD) techniques. The photocatalytic activity of TiO2-strewn rubber sheet was evaluated using Indigo Carmine (IC) dye as a model for organic dye pollutant in water. The results showed that the TiO2-strewn sheet could degrade IC dye solution under UV light irradiation. The effects of pH, initial concentration, and the intensity of UV light on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used TiO2-strewn sheet can be recovered and reused. The recycling uses did not require any cleaning between successive uses and no decline in the photodegradation efficiency was observed compared with freshly prepared TiO2-strewn sheet. PMID:22655360

  9. Enhanced photocatalytic activity in anodized WO3-loaded TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Nazari, M.; Golestani-Fard, F.; Bayati, R.; Eftekhari-Yekta, B.

    2015-04-01

    In this work, TiO2 and WO3-grafted TiO2 nanotubes were grown via anodizing of titanium substrates in tungstate containing electrolytes. The samples were characterized in detail by XRD, XPS, SEM, EDX, and UV-Vis spectrophotometry techniques. Besides, photocatalytic characteristics were evaluated through measuring the degradation rate of 4-chlorophenol to establish a correlation between structure and photochemical properties. We were able to control morphology and growth mode of nanotubes from a tubular to a worm-like structure by changing the electrolyte composition. The samples possessed an anatase-rutile matrix where the anatase/rutile ratio was found to increase with the concentration of tungstate in the electrolyte. We attributed this observation to change in electrical conductivity of the electrolyte and the heat generated on the substrates. It was unambiguously revealed that a composite of WO3 and TiO2 forms and, in parallel, tungsten is doped into the crystalline lattice of TiO2. The maximum photocatalytic reaction rate constant for TiO2 and WO3-TiO2 samples was determined to be 0.0131 and 0.0174 min-1 respectively. The grafting TiO2 nanotubes with WO3 enhances the photocatalytic activity mainly due to the hindrance of charge carrier recombination and the formation of a more acidic surface. We established a correlation between structure, stoichiometry, and photocatalytic characteristics of nanotubes.

  10. Heterostructured TiO2 Nanorod@Nanobowl Arrays for Efficient Photoelectrochemical Water Splitting.

    PubMed

    Wang, Wenhui; Dong, Jingya; Ye, Xiaozhou; Li, Yang; Ma, Yurong; Qi, Limin

    2016-03-01

    Heterostructured TiO2 nanorod@nanobowl (NR@NB) arrays consisting of rutile TiO2 nanorods grown on the inner surface of arrayed anatase TiO2 nanobowls are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The unique heterostructures with a hierarchical architecture are readily fabricated by interfacial nanosphere lithography followed by hydrothermal growth. Owing to the two-dimensionally arrayed structure of anatase nanobowls and the nearly radial alignment of rutile nanorods, the TiO2 NR@NB arrays provide multiple scattering centers and hence exhibit an enhanced light harvesting ability. Meanwhile, the large surface area of the NR@NB arrays enhances the contact with the electrolyte while the nanorods offer direct pathways for fast electron transfer. Moreover, the rutile/anatase phase junction in the NR@NB heterostructure improves charge separation because of the facilitated electron transfer. Accordingly, the PEC measurements of the TiO2 NR@NB arrays on the fluoride-doped tin oxide (FTO) substrate show significantly enhanced photocatalytic properties for water splitting. Under AM1.5G solar light irradiation, the unmodified TiO2 NR@NB array photoelectrode yields a photocurrent density of 1.24 mA cm(-2) at 1.23 V with respect to the reversible hydrogen electrode, which is almost two times higher than that of the TiO2 nanorods grown directly on the FTO substrate.

  11. Hydrogenated Anatase TiO2 as Lithium-Ion Battery Anode: Size-Reactivity Correlation.

    PubMed

    Zheng, Jing; Liu, Lei; Ji, Guangbin; Yang, Qifan; Zheng, Lirong; Zhang, Jing

    2016-08-10

    An improved hydrogenation strategy for controllable synthesis of oxygen-deficient anatase TiO2 (H-TiO2) is performed via adjusting the particle size of starting rectangular anatase TiO2 nanosheets from 90 to 30 nm. The morphology and structure characterizations obviously demonstrate that the starting materials of TiO2 nanosheets are transformed into nanoparticles with distinct size reduction; meanwhile, the concentration of oxygen vacancy is gradually increased with the decreasing particle size of starting TiO2. As a result, the Li-storage performance of H-TiO2 is not only much better than that of the pure TiO2 but also elevated stage by stage with the decreasing particle size of starting TiO2; especially the H-TiO2 with highest concentration of oxygen vacancy from smallest TiO2 nanosheets shows the best Li-storage performance with a stable discharge capacity 266 mAh g(-1) after 100 cycles at 1 C. Such excellent performance should be attributed to the joint action from oxygen vacancy and size effect, which promises significant enhancement of high electronic conductivity without weakening Li(+) diffusion via hydrogenation strategy.

  12. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-02-01

    Novel nanocomposite films, based on graphene oxide (GO) and TiO2 nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO2 nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO2 nanotube composite electrode compared with pristine TiO2 nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO2 nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO2 nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO2 nanotube arrays.

  13. Graphene oxide modified TiO2 nanotube arrays: enhanced visible light photoelectrochemical properties.

    PubMed

    Song, Peng; Zhang, Xiaoyan; Sun, Mingxuan; Cui, Xiaoli; Lin, Yuehe

    2012-03-01

    Novel nanocomposite films, based on graphene oxide (GO) and TiO(2) nanotube arrays, were synthesized by assembling GO on the surface of self-organized TiO(2) nanotube arrays through a simple impregnation method. The composite films were characterized with field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and UV-vis diffuse reflectance spectroscopy. The photoelectrochemical properties of the composite nanotube arrays were investigated under visible light illumination. Remarkably enhanced visible light photoelectrochemical response was observed for the GO decorated TiO(2) nanotube composite electrode compared with pristine TiO(2) nanotube arrays. The sensitizing effect of GO on the photoelectrochemical response of the TiO(2) nanotube arrays was demonstrated and about 15 times enhanced maximum photoconversion efficiency was obtained with the presence of GO. An enhanced photocatalytic activity of the TiO(2) nanotube arrays towards the degradation of methyl blue was also demonstrated after modification with GO. The results presented here demonstrate GO to be efficient for the improved utilization of visible light for TiO(2) nanotube arrays. PMID:22297577

  14. 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.

  15. Effects of TiO2 content on the microstructure, mechanical properties and photocatalytic activity of three dimensional TiO2-Graphene composite prepared by hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Shi, Xiangru; Chen, Jian; Wang, Wenxiu; Wang, Zengmei; Zhang, Yao; Guo, Xinli

    2016-07-01

    A series of three dimensional (3D) porous TiO2-graphene (TGR) hydrogel samples with different mass ratio of graphene to TiO2 were obtained using a one-step hydrothermal method. Their microstructure, mechanical properties, and photocatalytic activity were investigated. The TGR samples exhibited well defined interconnected 3D porous network microstructure and good mechanical strength. Moreover, the pore size and the compressive strength could be easily adjusted by changing the content of TiO2, showing a decreasing tendency with the increase of the relative content of TiO2. The results of the photodegradation of methylene blue indicated that the photocatalytic activity of the TGR samples can be significantly enhanced, compared to the pure TiO2 nanoparticles. The TGR sample also showed good durability and reusability. The mechanisms resulting in the improvement of photocatalytic activity were investigated with DRS, PL spectra, and adsorption experiment under dark conditions. It was found that adsorption is the dominant factor for the enhanced photocatalytic activity.

  16. Resistive switching characteristics in memristors with Al2O3/TiO2 and TiO2/Al2O3 bilayers

    NASA Astrophysics Data System (ADS)

    Alekseeva, Liudmila; Nabatame, Toshihide; Chikyow, Toyohiro; Petrov, Anatolii

    2016-08-01

    Differences between the resistive switching characteristics of Al2O3/TiO2 and TiO2/Al2O3 bilayer structures, fabricated by atomic layer deposition at 200 °C and post-deposition annealing, were studied in Pt bottom electrode (Pt-BE)/insulator/Pt top electrode (Pt-TE) capacitors. The Pt-BE/Al2O3/TiO2/Pt-TE capacitor exhibits stable bipolar resistive switching with an on-resistance/off-resistance ratio of ∼102 controlled by a small voltage of ±0.8 V. The forming process occurs in two steps of breaking of the Al2O3 layer and transfer of oxygen vacancies (VO) into the TiO2 layer. The capacitor showed poor endurance, particularly in the high-resistance state under vacuum conditions. This indicates that the insulating TiO2 layer without VO is not formed near the Al2O3 layer because oxygen cannot be introduced from the exterior. On the other hand, in the Pt-BE/TiO2/Al2O3/Pt-TE capacitor, multilevel resistive switching with several applied voltage-dependent nonvolatile states is observed. The switching mechanism corresponds to the Al2O3 layer’s trapped VO concentration, which is controlled by varying the applied voltage.

  17. Photoinduced Stepwise Oxidative Activation of a Chromophore–Catalyst Assembly on TiO2

    SciTech Connect

    Song, Wenjing; Glasson, Christopher R. K.; Luo, Hanlin; Hanson, Kenneth G.; Brennaman, Kyle M.; Concepcion, Javier J.; Meyer, Thomas J.

    2011-07-08

    To probe light-induced redox equivalent separation and accumulation, we prepared ruthenium polypyridyl molecular assembly [(dcb)2Ru(bpy-Mebim2py)Ru(bpy)(OH2)]4+ (RuaII–RubII–OH2) with Rua as light-harvesting chromophore and Rub as water oxidation catalyst (dcb = 4,4'-dicarboxylic acid-2,2'-bipyridine; bpy-Mebim2py = 2,2'-(4-methyl-[2,2':4',4''-terpyridine]-2'',6''-diyl)bis(1-methyl-1H-benzo[d]imidazole); bpy = 2,2'-bipyridine). When bound to TiO2 in nanoparticle films, it undergoes MLCT excitation, electron injection, and oxidation of the remote -RubII–OH2 site to give TiO2(e–)–RuaII–RubIII–OH23+ as a redox-separated transient. The oxidized assembly, TiO2–RuaII–RubIII–OH23+, similarly undergoes excitation and electron injection to give TiO2(e–)–RuaII–RubIV=O2+, with RubIV=O2+ a known water oxidation catalyst precursor. Injection efficiencies for both forms of the assembly are lower than those for [Ru(bpy)2(4,4'-(PO3H2)2bpy)]2+ bound to TiO2 (TiO2–Ru2+), whereas the rates of back electron transfer, TiO2(e–) → RubIII–OH23+ and TiO2(e–) → RubIV=O2+, are significantly decreased compared with TiO2(e–) → Ru3+ back electron transfer.

  18. [Spectrum characterization and fine structure of copper phthalocyanine-doped TiO2 microcavities].

    PubMed

    Liu, Cheng-lin; Zhang, Xin-yi; Zhong, Ju-hua; Zhu, Yi-hua; He, Bo; Wei, Shi-qiang

    2007-10-01

    Copper phthalocyanine-doped TiO2 microcavities were fabricated by chemistry method. Their spectrum characterization was studied by Fourier transform infrared (FTIR) and Raman spectroscopy, and their fine structure was analyzed by X-ray absorption fine structure (XAFS). The results show that there is interaction of copper phthalocyanine (CuPc) and TiO2 microcavities after TiO2 microcavities was doped with CuPc. For example, there is absorption at 900.76 cm(-1) in FTIR spectra, and the "red shift" of both OH vibration at 3392.75 cm(-1) and CH vibration at 2848.83 cm(-1). There exist definite peak shifts and intensity changes in infrared absorption in the C-C or C-N vibration in the planar phthalocyanine ring, the winding vibration of C-H inside and C-N outside plane of benzene ring. In Raman spectrum, there are 403.4, 592.1 and 679.1 cm(-1) characterized peaks of TiO2 in CuPc-doped TiO2 microcavities, but their wave-numbers show shifts to anatase TiO2. The vibration peaks at 1586.8 and 1525.6 cm(-1) show that there exists the composite material of CuPc and TiO2. These changes are related to the plane tropism of the molecule structure of copper phthalocyanine. XAFS showed tetrahedron TiO4 structure of Ti in TiO2 microcavities doped with copper phthalocyanine, and the changes of inner "medial distances" and the surface structure of TiO2 microcavities.

  19. Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins.

    PubMed

    Shirkavand, Saeed; Moslehifard, Elnaz

    2014-01-01

    Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001). Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength.

  20. Antibacterial activity of DLC films containing TiO2 nanoparticles.

    PubMed

    Marciano, F R; Lima-Oliveira, D A; Da-Silva, N S; Diniz, A V; Corat, E J; Trava-Airoldi, V J

    2009-12-01

    Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties. PMID:19758597

  1. TiO2-BASED Composite Films for the Photodegradation of Oxytetracycline

    NASA Astrophysics Data System (ADS)

    Li, Hui; Guan, Ling-Xiao; Feng, Ji-Jun; Li, Fang; Yao, Ming-Ming

    2015-02-01

    The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO2-SiO2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO2-SiO2 film was composed of smaller nanoparticles compared to pure TiO2 or TiO2-SiO2 film. The BET surface area results showed that the specific surface area of the pure TiO2, TiO2-SiO2 and Ca2+/Fe3+ co-doped TiO2-SiO2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO2-SiO2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe/Ca co-doped TiO2-SiO2 film is effective in the degradation of OTC under both UV and visible light irradiation.

  2. Photodegradation of phenanthrene by N-doped TiO2 photocatalyst.

    PubMed

    Sirisaksoontorn, Weekit; Thachepan, Surachai; Songsasen, Apisit

    2009-07-15

    The photodegradation of phenanthrene has been catalyzed by nanostructures of TiO2 doped with nitrogen, N-doped TiO2. The N-doped TiO2 was prepared from the sol-gel reaction of Titanium(IV) bis(ethyl acetoacetato)diisopropoxide with 25% ammonia solution. The N-doped TiO2 was calcined at various temperatures from 300 to 700 degrees C. X-ray diffraction (XRD) results showed that N-doped TiO2 remained amorphous at 300 degrees C but anatase-to-rutile transformation started at 400 degrees C and was complete at 700 degrees C. The average particle size calculated from Scherrer's equation was in the range of 9-51 nm with surface area (S(BET)) of 253.7-4.8 m2/g. X-ray photoelectron spectroscopy (XPS) results confirmed the incorporation of nitrogen atoms (Ti-N bond) in the N-doped catalyst. Moreover, the percentage of nitrogen determined by Elemental analysis was 0.236% of N-doped calcined at 400 degrees C. UV-Vis reflection spectra indicated that N-doped TiO2 calcined at 400 degrees C shifted to the higher absorption edge in the range of visible light. N-doped TiO2 calcined at 400 degrees C successfully catalyzed the photodegradation of phenanthrene (80% conversion) whereas N-doped TiO2 calcined at 500 degrees C and P25 TiO2 failed as catalysts.

  3. Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins

    PubMed Central

    Shirkavand, Saeed; Moslehifard, Elnaz

    2014-01-01

    Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001). Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength. PMID:25587380

  4. Antibacterial activity of DLC films containing TiO2 nanoparticles.

    PubMed

    Marciano, F R; Lima-Oliveira, D A; Da-Silva, N S; Diniz, A V; Corat, E J; Trava-Airoldi, V J

    2009-12-01

    Diamond-like carbon (DLC) films have been the focus of extensive research in recent years due to their potential applications as surface coatings on biomedical devices. Titanium dioxide (TiO2) in the anatase crystalline form is a strong bactericidal agent when exposed to near-UV light. In this work we investigate the bactericidal activity of DLC films containing TiO2 nanoparticles. The films were grown on 316L stainless-steel substrates from a dispersion of TiO2 in hexane using plasma-enhanced chemical vapor deposition. The composition, bonding structure, surface energy, stress, and surface roughness of these films were also evaluated. The antibacterial tests were performed against Escherichia coli (E. coli) and the results were compared to the bacterial adhesion force to the studied surfaces. The presence of TiO2 in DLC bulk was confirmed by Raman spectroscopy. As TiO2 content increased, I(D)/I(G) ratio, hydrogen content, and roughness also increased; the films became more hydrophilic, with higher surface free energy and the interfacial energy of bacteria adhesion decreased. Experimental results show that TiO2 increased DLC bactericidal activity. Pure DLC films were thermodynamically unfavorable to bacterial adhesion. However, the chemical interaction between the E. coli and the studied films increased for the films with higher TiO2 concentration. As TiO2 bactericidal activity starts its action by oxidative damage to the bacteria wall, a decrease in the interfacial energy of bacteria adhesion causes an increase in the chemical interaction between E. coli and the films, which is an additional factor for the increasing bactericidal activity. From these results, DLC with TiO2 nanoparticles can be useful for producing coatings with antibacterial properties.

  5. Ag Nanorods Coated with Ultrathin TiO2 Shells as Stable and Recyclable SERS Substrates

    NASA Astrophysics Data System (ADS)

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Xie, Zheng; Zhang, Zhengjun

    2015-10-01

    TiO2-coated Ag nanorods (Ag@TiO2 NRs) have been fabricated as multifunctional surface-enhanced Raman scattering (SERS) substrates. Uniform TiO2 shells could sufficiently protect the internal Ag NRs against oxidation and sulfuration, thus the temporal stability of SERS substrates was markedly improved. Meanwhile, due to the synergetic effect between crystalline TiO2 and Ag, the nanocomposites could clean themselves via photocatalytic degradation of the adsorbed molecules under ultraviolet irradiation and water dilution, making the SERS substrates renewable. Such Ag@TiO2 NRs were shown to serve as outstanding SERS sensors featuring high sensitivity, superior stability and recyclability.

  6. Fabrication and photocatalytic activity of TiO2 derived nanotubes with Ag ions doping.

    PubMed

    Liu, Fang; Lai, Shuting; Huang, Peilin; Liu, Yingju; Xu, Yuehua; Fang, Yueping; Zhou, Wuyi

    2012-11-01

    Ag/TiO2 nanotubes with uniform distribution were successfully prepared by a hydrothermal-dipping method. The synthesized samples were characterized by XRD, TEM and FTIR, respectively. The results exhibited that the morphological structure of the TiO2 nanotubes was improved by the doping of Ag ions. The photocatalytic degradation experiment indicated that the photocatalytic activity of the Ag/TiO2 nanotubes indicated better photocatalytic activity than pure TiO2 nanotubes since silver was able to help the electron-hole separation by attracting photoelectrons. The optimal mol ration of TiO2 and AgNO3 was 25:1.

  7. Doping of TiO 2 Polymorphs for Altered Optical and Photocatalytic Properties

    DOE PAGES

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; Sohlberg, Karl

    2009-01-01

    Tmore » his paper reviews recent investigations of the influence of dopants on the optical properties of TiO 2 polymorphs.he common undoped polymorphs of TiO 2 are discussed and compared.he results of recent doping efforts are tabulated, and discussed in the context of doping by elements of the same chemical group. Dopant effects on the band gap and photocatalytic activity are interpreted with reference to a simple qualitative picture of the TiO 2 electronic structure, which is supported with first-principles calculations.« less

  8. Synthesis and characterization of TiO2 nanostructure thin films grown by thermal CVD

    NASA Astrophysics Data System (ADS)

    Rizal, Umesh; Das, Soham; Kumar, Dhruva; Swain, Bhabani S.; Swain, Bibhu P.

    2016-04-01

    Thermal Chemical Vapor Deposition (CVD) deposited Titanium dioxide nanostructures (TiO2-NSs) were grown by using Ti powder and O2 precursors on Si/SiO2 (100) substrate. The microstructure and vibration properties of TiO2-NSs were characterized by Fourier transform infrared (FTIR), SEM, and photoluminescence (PL) spectroscopy. The role of O2 flow rate on TiO2-NSs revealed decreased deposition rate, however, surface roughness has been increased resulted into formation of nanostructure thin films.

  9. Ag Nanorods Coated with Ultrathin TiO2 Shells as Stable and Recyclable SERS Substrates

    PubMed Central

    Ma, Lingwei; Huang, Yu; Hou, Mengjing; Xie, Zheng; Zhang, Zhengjun

    2015-01-01

    TiO2-coated Ag nanorods (Ag@TiO2 NRs) have been fabricated as multifunctional surface-enhanced Raman scattering (SERS) substrates. Uniform TiO2 shells could sufficiently protect the internal Ag NRs against oxidation and sulfuration, thus the temporal stability of SERS substrates was markedly improved. Meanwhile, due to the synergetic effect between crystalline TiO2 and Ag, the nanocomposites could clean themselves via photocatalytic degradation of the adsorbed molecules under ultraviolet irradiation and water dilution, making the SERS substrates renewable. Such Ag@TiO2 NRs were shown to serve as outstanding SERS sensors featuring high sensitivity, superior stability and recyclability. PMID:26486994

  10. Photoelectrochemical deoxyribonucleic acid sensing on a nanostructured TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Tokudome, Hiromasa; Yamada, Yoko; Sonezaki, Shuji; Ishikawa, Hiroshi; Bekki, Makoto; Kanehira, Koki; Miyauchi, Masahiro

    2005-11-01

    A nanostructured TiO2 electrode chemisorbed with probe deoxyribonucleic acid (DNA) can photoelectrochemically detect a dye-labeled target DNA molecule. After the hybridization between the probe and target DNA molecules, light irradiation generates electrons in the dye molecules, and these electrons are injected into the TiO2 electrode. The resulting photocurrent can be measured and corresponds to the concentration of target DNA. This sensor can quantitatively detect target DNA at lower than nanomolar concentrations. In addition, by utilizing two different dyes, different DNA sequences can be detected on the TiO2 electrode.

  11. Enhanced Photodetection from TiO2-SiO x -TiO2 One-Dimensional Device

    NASA Astrophysics Data System (ADS)

    Choudhuri, Bijit; Mondal, Aniruddha; Saha, Ardhendu

    2016-08-01

    In this work, TiO2 nanowires (NWs)/SiO x zigzag (ZZ) film/TiO2 NWs structure-based devices were fabricated using glancing angle deposition and oblique angle deposition techniques. An investigation of the optoelectronic properties of the devices will be presented. The NWs-ZZ-NWs structure showed an average of 1.6 times enhancement in absorbance value as compared to the absorbance of the structure that contains only NWs. When irradiated with white light, NWs-ZZ-NWs- and only NWs-based devices exhibited a maximum 6.3 and 2.7 times greater light-to-dark current ratio, respectively, at -3 V. The maximum photoresponsivity and internal gain at the wavelength of 370 nm were calculated to be 57 A/W and 191, respectively, for the NWs-ZZ-NWs devices. The rise and fall time for the NWs-ZZ-NWs and NW devices were 16.56 s and 8.2 s, and 8.39 s and 7.31 s, respectively.

  12. Anatase mesoporous TiO2 nanofibers with high surface area for solid-state dye-sensitized solar cells.

    PubMed

    Zhang, Wei; Zhu, Rui; Ke, Lin; Liu, Xizhe; Liu, Bin; Ramakrishna, Seeram

    2010-10-01

    Mesoporous nanofibers (NFs) with a high surface area of 112 m(2)/g have been prepared by electrospinning technique. The structures of mesoporous NFs and regular NFs are characterized and compared through scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and selected area electron diffraction (SAED) studies. Using mesoporous TiO(2) NFs as the photoelectrode, solid-state dye-sensitized solar cells (SDSCs) have been fabricated employing D131 as the sensitizer and P3HT as the hole transporting material to yield an energy conversion efficiency (η) of 1.82%. A J(sc) of 3.979 mA cm(-2) is obtained for mesoporous NF-based devices, which is 3-fold higher than that (0.973 mA cm(-2)) for regular NF-based devices fabricated under the same condition (η = 0.42%). Incident photon-to-current conversion efficiency (IPCE) and dye-desorption test demonstrate that the increase in J(sc) is mainly due to greatly improved dye adsorption for mesoporous NFs as compared to that for regular NFs. In addition, intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) measurements indicate that the mesopores on NF surface have very minor effects on charge transport and collection. Initial aging test proves good stability of the fabricated devices, which indicates the promise of mesoporous NFs as photoelectrode for low-cost SDSCs.

  13. 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; Reno, John L.; Chung Seu, U-Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg

    2016-06-27

    Monocrystalline titanium dioxide (TiO2) 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 TiO2 spheres have narrow linewidths of only tens of gigahertz. Lastly, anisotropic TiO2 micro-resonators can be used to enhance the interplay of magnetic and electric dipolemore » resonances in the emerging THz all-dielectric metamaterial technology.« less

  14. Antifungal activity of TiO2 photocatalysis against Penicillium expansum in vitro and in fruit tests.

    PubMed

    Maneerat, Chamorn; Hayata, Yasuyoshi

    2006-03-15

    The antifungal activity of TiO2 photocatalytic reaction in the form of TiO2 powder and TiO2 coated on a plastic film against Penicillium expansum was investigated in vitro and in fruit tests. The mixture of P. expansum conidial suspension and TiO2 powder was added to potato dextrose agar (PDA) plates for vitro test. The TiO2 photocatalytic reaction reduced conidial germination of the fungal pathogen. It was found that the ability of the TiO2 photocatalytic reaction to suppress P. expansum growth correlated to the amount of TiO2 added. Lower numbers of viable colonies of P. expansum were observed with increasing amount of TiO2. Regardless of the kind of selected fruit inoculated with P. expansum, both TiO2 powder and TiO2-coated film exhibited antifungal activity to control fruit rot. Development of Penicillium rot in apple was significantly (P = 0.05) retarded by the TiO2 photocatalytic reaction. Similarly the TiO2 photocatalytic reaction was the only treatment where no tomato fruit rot was noticeable after 1 week of storage. TiO2-coated film also decreased brown lesions and Penicillium rot infection in lemons. The mean severity fruit rot scores (browning and softening flesh) were 3.2 and 1.9 for uncoated and TiO2-coated film, respectively. Our findings suggest that "TiO2 photocatalytic reaction" shows antifungal activity against P. expansum which may have potential for postharvest disease control.

  15. Electron channeling in TiO2 coated Cu layers

    NASA Astrophysics Data System (ADS)

    Zheng, Pengyuan; Zhou, Tianji; Gall, Daniel

    2016-05-01

    Electron transport in metal conductors with ∼5–30 nm width is dominated by surface scattering. In situ transport measurements as a function of surface chemistry demonstrate that the primary parameter determining the surface scattering specularity is the localized surface density of states at the Fermi level N(E f ). In particular, the measured sheet resistance of epitaxial Cu(001) layers with thickness d Cu = 9–25 nm increases when coated with d Ti = 0.1–4.0 monolayers (MLs) of Ti, but decreases again during exposure to 37 Pa of O2. These resistivity changes are a function of d Cu and d Ti and are due to a transition from partially specular electron scattering at the Cu surface to completely diffuse scattering at the Cu–Ti interface, and the recovery of surface specularity as the Ti is oxidized. X-ray reflectivity and photoelectron spectroscopy indicate the formation of a 0.47 ± 0.03 nm thick Cu2O surface layer on top of the TiO2–Cu2O during air exposure, while density functional calculations of TiO x cap layers as a function of x = 0–2 and d Ti = 0.25–1.0 ML show a reduction of N(E f ) by up to a factor of four. This reduction is proposed to be the key cause for the recovery of surface specularity and results in electron confinement and channeling in the Cu layer upon Ti oxidation. Transport measurements at 293 and 77 K confirm the channeling and demonstrate the potential for high-conductivity metal nanowires by quantifying the surface specularity parameter p = 0.67 ± 0.05, 0.00 ± 0.05, and 0.35 ± 0.05 at the Cu–vacuum, Cu–Ti, and Cu–TiO2 interfaces.

  16. Electrokinetic Properties of TiO2 Nanotubular Surfaces

    NASA Astrophysics Data System (ADS)

    Lorenzetti, Martina; Gongadze, Ekaterina; Kulkarni, Mukta; Junkar, Ita; Iglič, Aleš

    2016-08-01

    Surface charge is one of the most significant properties for the characterisation of a biomaterial, being a key parameter in the interaction of the body implant with the surrounding living tissues. The present study concerns the systematic assessment of the surface charge of electrochemically anodized TiO2 nanotubular surfaces, proposed as coating material for Ti body implants. Biologically relevant electrolytes (NaCl, PBS, cell medium) were chosen to simulate the physiological conditions. The measurements were accomplished as titration curves at low electrolytic concentration (10-3 M) and as single points at fixed pH but at various electrolytic concentrations (up to 0.1 M). The results showed that all the surfaces were negatively charged at physiological pH. However, the zeta potential values were dependent on the electrolytic conditions (electrolyte ion concentration, multivalence of the electrolyte ions, etc.) and on the surface characteristics (nanotubes top diameter, average porosity, exposed surface area, wettability, affinity to specific ions, etc.). Accordingly, various explanations were proposed to support the different experimental data among the surfaces. Theoretical model of electric double layer which takes into account the asymmetric finite size of ions in electrolyte and orientational ordering of water dipoles was modified according to our specific system in order to interpret the experimental data. Experimental results were in agreement with the theoretical predictions. Overall, our results contribute to enrich the state-of-art on the characterisation of nanostructured implant surfaces at the bio-interface, especially in case of topographically porous and rough surfaces.

  17. Electrokinetic Properties of TiO2 Nanotubular Surfaces.

    PubMed

    Lorenzetti, Martina; Gongadze, Ekaterina; Kulkarni, Mukta; Junkar, Ita; Iglič, Aleš

    2016-12-01

    Surface charge is one of the most significant properties for the characterisation of a biomaterial, being a key parameter in the interaction of the body implant with the surrounding living tissues. The present study concerns the systematic assessment of the surface charge of electrochemically anodized TiO2 nanotubular surfaces, proposed as coating material for Ti body implants. Biologically relevant electrolytes (NaCl, PBS, cell medium) were chosen to simulate the physiological conditions. The measurements were accomplished as titration curves at low electrolytic concentration (10(-3) M) and as single points at fixed pH but at various electrolytic concentrations (up to 0.1 M). The results showed that all the surfaces were negatively charged at physiological pH. However, the zeta potential values were dependent on the electrolytic conditions (electrolyte ion concentration, multivalence of the electrolyte ions, etc.) and on the surface characteristics (nanotubes top diameter, average porosity, exposed surface area, wettability, affinity to specific ions, etc.). Accordingly, various explanations were proposed to support the different experimental data among the surfaces. Theoretical model of electric double layer which takes into account the asymmetric finite size of ions in electrolyte and orientational ordering of water dipoles was modified according to our specific system in order to interpret the experimental data. Experimental results were in agreement with the theoretical predictions. Overall, our results contribute to enrich the state-of-art on the characterisation of nanostructured implant surfaces at the bio-interface, especially in case of topographically porous and rough surfaces. PMID:27562014

  18. Conversion of Nanocellulose Aerogel into TiO2 and TiO2@C Nano-thorns by Direct Anhydrous Mineralization with TiCl4. Evaluation of Electrochemical Properties in Li Batteries.

    PubMed

    Henry, Aurélien; Plumejeau, Sandrine; Heux, Laurent; Louvain, Nicolas; Monconduit, Laure; Stievano, Lorenzo; Boury, Bruno

    2015-07-15

    Nanostructured TiO2 and TiO2@C nanocomposites were prepared by an original process combining biotemplating and mineralization of aerogels of nanofibrillated cellulose (NFC). A direct one step treatment of NFC with TiCl4 in strictly anhydrous conditions allows TiO2 formation at the outermost part of the nanofibrils while preserving their shape and size. Such TiO2@cellulose composites can be transformed into TiO2 nanotubes (TiO2-NT) by calcination in air at 600 and 900 °C, or into TiO2@C nanocomposites by pyrolysis in argon at 600 and 900 °C. Detailed characterization of these materials is reported here, along with an assessment of their performance as negative electrode materials for Li-ion batteries. PMID:25881329

  19. Dip coated TiO2 nanostructured thin film: synthesis and application

    NASA Astrophysics Data System (ADS)

    Vanaraja, Manoj; Muthukrishnan, Karthika; Boomadevi, Shanmugam; Karn, Rakesh Kumar; Singh, Vijay; Singh, Pramod K.; Pandiyan, Krishnamoorthy

    2016-02-01

    TiO2 thin film was fabricated by dip coating method using titanium IV chloride as precursor and sodium carboxymethyl cellulose as thickening as well as capping agent. Structural and morphological features of TiO2 thin film were characterized by X-ray diffractometer and field emission scanning electron microscope, respectively. Crystallinity of the film was confirmed with high-intensity peak at (101) plane, and its average crystallite size was found to be 28 nm. The ethanol-sensing properties of TiO2 thin film was studied by the chemiresistive method. Furthermore, various gases were tested in order to verify the selectivity of the sensor. Among the several gases, the fabricated TiO2 sensor showed very high selectivity towards ethanol at room temperature.

  20. Photocatalytic Property of TiO2-Vermiculite Composite Nanofibers via Electrospinning.

    PubMed

    Tang, Chao; Hu, Meiling; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Liu, Wenjuan; Wang, Meng; Huang, Zhaohui

    2015-12-01

    Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol-gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials' ability to degrade methylene blue. PMID:26130024

  1. Effects of Mn doping on surface enhanced Raman scattering properties of TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Xue, Xiangxin; Ji, Wei; Mao, Zhu; Li, Zhishi; Ruan, Weidong; Zhao, Bing; Lombardi, John R.

    2012-09-01

    TiO2 and Mn-doped TiO2 (1%, 3% and 5%) nanoparticles (NPs) were synthesized by a sol-hydrothermal method for surface-enhanced Raman spectroscopy study. When using the 4-mercaptobenzoic acid (4-MBA) as the probing molecule, optimum SERS signals were observed on the Mn-TiO2 (3%) samples. On the 3% Mn doped TiO2 substrate, 4-MBA molecules exhibit a higher SERS intensity by a factor of six as compared with the native enhancement of 4-MBA adsorbed on pure TiO2 NPs. The possible mechanism for the phenomena is also discussed. This study opens up a new dimension for the family of SERS substrates.

  2. Comparison of Au and TiO2 based catalysts for the synthesis of chalcogenide nanowires

    NASA Astrophysics Data System (ADS)

    Schönherr, P.; Prabhakaran, D.; Jones, W.; Dimitratos, N.; Bowker, M.; Hesjedal, T.

    2014-06-01

    We present a comparative study of TiO2-based and Au catalysts for the physical vapor deposition of (Bi1-xSbx)2Se3 topological insulator nanowires. The standard Au nanoparticle catalyst was compared to five TiO2 nanoparticle based catalysts (anatase, rutile, P-25, high surface area anatase, and TiO2 supported Au particles). The use of Au nanoparticles seriously harms the properties of nanowires, thereby limiting their application. In contrast, TiO2 based catalysts lead to the residue-free growth of nanowires with a higher degree of crystallinity. Homogeneous nanowire ensembles are achieved with the mixed phase P-25 catalyst, and a possible growth mechanism is proposed.

  3. Molecular Hydrogen Formation from Proximal Glycol Pairs on TiO2(110)

    SciTech Connect

    Chen, Long; Li, Zhenjun; Smith, R. Scott; Kay, Bruce D.; Dohnalek, Zdenek

    2014-04-16

    Understanding hydrogen formation on TiO2 surfaces is of great importance as it could provide fundamental insight into water splitting for hydrogen production using solar energy. In this work, hydrogen formation from glycols having different numbers of methyl end-groups have been studied using temperature pro-grammed desorption on reduced, hydroxylated, and oxidized TiO2(110) surfaces. The results from OD-labeled glycols demon-strate that gas-phase molecular hydrogen originates exclusively from glycol hydroxyl groups. The yield is controlled by a combi-nation of glycol coverage, steric hindrance, TiO2(110) order and the amount of subsurface charge. Combined, these results show that proximal pairs of hydroxyl aligned glycol molecules and subsurface charge are required to maximize the yield of this redox reaction. These findings highlight the importance of geometric and electronic effects in hydrogen formation from adsorbates on TiO2(110).

  4. Atomic Structure of the Anatase TiO2(001) Surface

    SciTech Connect

    Xia, Yaobiao; Zhu, Ke; Kaspar, Tiffany C.; Du, Yingge; Birmingham, Blake; Park, Kenneth T.; Zhang, Zhenrong

    2013-08-16

    Understanding the structure of well-defined anatase TiO2 surfaces is critical for deciphering site-specific thermal and photo- reaction mechanisms on anatase TiO2. Using UHV scanning tunneling microscopy (STM), we have studied the atomic structure of anatase TiO2(001) epitaxial thin films grown by oxygen plasma assisted molecular beam epitaxy. Bright rows of the (1×4) reconstructed surface are resolved as three types of features with different sizes. High-resolution STM images taken from the same area at different bias voltages show that these individual features are originated from combinations of two basic atomic building blocks. We propose a modified added molecule model for the anatase TiO2 (001) surface structure.

  5. Phase stability frustration on ultra-nanosized anatase TiO2

    PubMed Central

    Patra, Snehangshu; Davoisne, Carine; Bouyanfif, Houssny; Foix, Dominique; Sauvage, Frédéric

    2015-01-01

    This work sheds light on the exceptional robustness of anatase TiO2 when it is downsized to an extreme value of 4 nm. Since at this size the surface contribution to the volume becomes predominant, it turns out that the material becomes significantly resistant against particles coarsening with temperature, entailing a significant delay in the anatase to rutile phase transition, prolonging up to 1000 °C in air. A noticeable alteration of the phase stability diagram with lithium insertion is also experienced. Lithium insertion in such nanocrystalline anatase TiO2 converts into a complete solid solution until almost Li1TiO2, a composition at which the tetragonal to orthorhombic transition takes place without the formation of the emblematic and unwished rock salt Li1TiO2 phase. Consequently, excellent reversibility in the electrochemical process is experienced in the whole portion of lithium content. PMID:26042388

  6. Porous Anatase TiO2 Thin Films for NH3 Vapour Sensing

    NASA Astrophysics Data System (ADS)

    Ponnusamy, Dhivya; Madanagurusamy, Sridharan

    2015-12-01

    Anatase titanium dioxide (TiO2) thin films were deposited onto cleaned glass substrates by a direct current (DC) reactive magnetron sputtering technique for different deposition times from 10 min to 40 min, which resulted in films of different thicknesses. Characterization techniques, such as x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) were used to characterize the structural and morphological properties of the TiO2 thin films. XRD patterns showed the formation of (101) crystal anatase facets. The grain size values of the film increased with increased deposition time, and the films deposited at 40 min exhibited a porous structure. Anatase TiO2 thin films exhibited excellent sensing response, fast response and recovery time, as well as good stability and selectivity towards ammonia (NH3). The enhanced NH3 sensing behavior of anatase TiO2 films is attributed to the porous morphology and oxygen vacancies.

  7. TiO2 Nanoparticles as a Soft X-ray Molecular Probe

    SciTech Connect

    Larabell, Carolyn; Ashcroft, Jared M.; Gu, Weiwei; Zhang, Tierui; Hughes, Steven M.; Hartman, Keith B.; Hofmann, Cristina; Kanaras, Antonios G.; Kilcoyne, David A.; Le Gros, Mark; Yin, Yadong; Alivisatos, A. Paul; Larabell, Carolyn A.

    2007-06-30

    With the emergence of soft x-ray techniques for imaging cells, there is a pressing need to develop protein localization probes that can be unambiguously identified within the region of x-ray spectrum used for imaging. TiO2 nanocrystal colloids, which have a strong absorption cross-section within the "water-window" region of x-rays, areideally suited as soft x-ray microscopy probes. To demonstrate their efficacy, TiO2-streptavidin nanoconjugates were prepared and subsequently labeled microtubules polymerized from biotinylated tubulin. The microtubules were imaged using scanning transmission x-ray microscopy (STXM), and the TiO2 nanoparticle tags were specifically identified using x-ray absorption near edge spectroscopy (XANES). These experiments demonstrate that TiO2 nanoparticles are potential probes for protein localization analyses using soft x-ray microscopy.

  8. Molecular design of TiO2 for gigantic red shift via sublattice substitution.

    PubMed

    Shao, Guosheng; Deng, Quanrong; Wan, Lin; Guo, Meilan; Xia, Xiaohong; Gao, Yun

    2010-11-01

    The effects of 3d transition metal doping in TiO2 phases have been simulated in detail. The results of modelling indicate that Mn has the biggest potential among 3d transition metals, for the reduction of energy gap and the introduction of effective intermediate bands to allow multi-band optical absorption. On the basis of theoretical formulation, we have incorporated considerable amount of Mn in nano-crystalline TiO2 materials. Mn doped samples demonstrate significant red shift in the optical absorption edge, with a secondary absorption edge corresponding to theoretically predicted intermediate bands/states. The gigantic red shift achievable in Mn-doped TiO2 is expected to extend the useful TiO2 functionalities well beyond the UV threshold via the optical absorption of both visible and infrared photon irradiance.

  9. Probing interactions between TiO 2 photocatalyst and adsorbing species using quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Morand, R.; Noworyta, K.; Augustynski, J.

    2002-10-01

    Photoactivity of nanocrystalline TiO 2 films is shown to be strongly affected by the presence in aqueous solution of salicylic acid, known to form Ti(IV)salicylate surface complexes. In particular, the photooxidation of methanol - an effective hole scavenger - at TiO 2 appears to be in part, or even completely inhibited by the additions of increasing amounts of salicylic acid. The chemisorption of salicylic and also phthalic acid on TiO 2 was followed using quartz crystal microbalance, QCM. The observed resonant frequency changes of the quartz crystal bearing TiO 2 films, accompanying increasing additions of the benzoic acids to the contacting solutions, indicate large displacement of water as a consequence of the adsorbent-imparted hydrophobicity of the interface.

  10. Amine functionalized TiO2-carbon nanotube composite: synthesis, characterization and application to glucose biosensing

    NASA Astrophysics Data System (ADS)

    Tasviri, Mahboubeh; Rafiee-Pour, Hossain-Ali; Ghourchian, Hedayatollah; Gholami, Mohammad Reza

    2011-12-01

    The synthesis of amine functionalized TiO2-coated multiwalled carbon nanotubes (NH2-TiO2-CNTs) using sol-gel method was investigated. The synthesized nanocomposite was characterized with XRD, FTIR spectroscopy, BET test and SEM imaging. The results demonstrated a unique nanostructure with no destruction of the CNTs' shape. In addition, the presence of amine groups on the composite surface was confirmed by FTIR. This nanocomposite was used for one-step immobilization of glucose oxidase (GOx) to sense glucose. The result of cyclic voltammetry showed a pair of well-defined and quasi-reversible peaks for direct electron transfer of GOx in the absence of glucose. Also, the result of electrochemical impedance spectroscopy indicated that GOx was successfully immobilized on the surface of NH2-TiO2-CNTs. Furthermore, good amperometric response showed that immobilized GOx on the NH2-TiO2-CNTs exhibits exceptional bioelectrocatalytic activity toward glucose oxidation.

  11. Deposition of Co-doped TiO2 Thin Films by sol-gel method

    NASA Astrophysics Data System (ADS)

    Boutlala, A.; Bourfaa, F.; Mahtili, M.; Bouaballou, A.

    2016-03-01

    Cobalt doped TiO2 thin films have been prepared by sol-gel method onto glass substrate at room temperature. in this present work, we are interesting to study the effect of Cobalt doped TiO2 thin films.the concentration of Co was varied from 0 to 6%at .The obtained films have been annealed at 500°C for 2 hours. X-ray diffraction patterns showed that Co: TiO2 films are polycrystalline with a tetragonal anatase and orthorhombic brookite types structures. The surface morphologies of the TiO2 doped with cobalt thin films were evaluated by Atomic Force Microscopy (AFM). The optical properties were studied by mean of UV-visible and near infrared spectroscopy.The calculated optical band gap decreases from 3.30 to 2.96 eV with increasing Co doping.

  12. 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...

  13. Composite TiO2-Carbon nano films with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Chakarov, Dinko; Sellappan, Raja

    2011-03-01

    Composite TiO2-carbon thin films prepared by physical vapor deposition techniques on fused silica substrates show enhanced photocatalytic activity, as compared to pure TiO2 films of similar thickness, towards decomposition of methanol to CO2 and water. Raman and XRD measurements confirm that annealed TiO2 films exhibit anatase structure while the carbon layer becomes graphitic. Characteristic for the composite films is an enhanced optical absorption in the visible range. The presence of the carbon film causes a shift of the TiO2 absorption edge and modifies its grain size to be smaller. The observed enhancement is attributed to synergy effects at the carbon-TiO2 interface, resulting in smaller crystallite size and anisotropic charge carrier transport, which in turn reduces their recombination probability. Supported by N-INNER through the Solar Hydrogen project (P30938-1 Solväte).

  14. Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

    NASA Astrophysics Data System (ADS)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Chattopadhyay, P. P.; Bhattacharyya, P.

    2014-08-01

    Oxygen vacancy (OV) controlled TiO2 nanotubes, having diameters of 50-70 nm and lengths of 200-250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH4F and ethylene glycol with selective H2O content. The structural evolution of TiO2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  15. Microwave-assisted synthesis of nanocrystalline TiO2 for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kuo, Ta-Chuan; Guo, Tzung-Fang; Chen, Peter

    2012-09-01

    The main purposes of this study are replacing conventional hydro-thermal method by microwave heating using water as reaction medium to rapidly synthesize TiO2.Titanium tetraisopropoxide (TTIP) was hydrolyzed in water. The solution is subsequently processed with microwave heating for crystal growth. The reaction time could be shortened into few minutes. Then we chose different acids as dispersion agents to prepare TiO2 paste for investigating the effects of dispersion on the power conversion efficiency of dye-sensitized solar cells (DSCs). The photovoltaic performance of the microwave-assisted synthesized TiO2 achieved power conversion efficiency of 6.31% under AM 1.5 G condition (100 mW/cm2). This PCE value is compatible with that of the devices made from commercial TiO2.

  16. Preparation TiO2 core-shell nanospheres and application as efficiency drug detection sensor

    PubMed Central

    2014-01-01

    In this paper, we report the facile preparation of monodisperse titanium dioxide-diltiazem/tetrachlorobismuth core-shell nanospheres (TiO2@DTMBi), in which, diltiazem (DTM)/tetrachlorobismuth (BiCl4) complexes were employed as electroactive materials. The morphology, size, formation, and structure of the obtained TiO2@DTMBi spheres were investigated by transmission electron microscopy, scanning electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and X-ray diffraction. The optimal condition of obtained monodisperse 40-nm TiO2@DTMBi spheres was researched. The results of using TiO2@DTMBi nanospheres as proposed drug sensor indicate a wide linear range (10-7 to 10-1 M) and a very low detection limit of 0.20 μg/mL. PMID:25246870

  17. Photocatalytic Property of TiO2-Vermiculite Composite Nanofibers via Electrospinning.

    PubMed

    Tang, Chao; Hu, Meiling; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Liu, Wenjuan; Wang, Meng; Huang, Zhaohui

    2015-12-01

    Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol-gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials' ability to degrade methylene blue.

  18. Photocatalytic Property of TiO2-Vermiculite Composite Nanofibers via Electrospinning

    NASA Astrophysics Data System (ADS)

    Tang, Chao; Hu, Meiling; Fang, Minghao; Liu, Yangai; Wu, Xiaowen; Liu, Wenjuan; Wang, Meng; Huang, Zhaohui

    2015-07-01

    Titanium dioxide (TiO2) is one of the most common photocatalysts. In this study, TiO2-vermiculite composite nanofibers with a mesh structure and a diameter of approximately 300 nm were prepared via sol-gel approach combined with electrospinning technique. The samples were characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, etc. The photocatalytic property was also evaluated. The TiO2-vermiculite composite nanofibers annealed at 550 °C for 3 h exhibited the best absorption and photo-degradation ability for the treatment of methylene blue. The results implied that the combination of mineral vermiculite powders with TiO2 enhanced the absorption-degradation performance of the as-prepared photocatalytic materials, consequently promoting the materials' ability to degrade methylene blue.

  19. Morphology dependent catalytic activity of TiO2 nanostructures towards photodegradation of Rose Bengal

    NASA Astrophysics Data System (ADS)

    Malik, Ritu; Kumar, Ashok; Nehra, S. P.; Rana, Pawan S.

    2015-08-01

    This work deals with the synthesis of TiO2 nanostructures using sol-gel and hydrothermal method for evaluating their photodegradation performance towards decolorization of Rose Bengal (RB). A combination of characterization techniques including X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy were utilized to evaluate the structural, morphological and optical properties of the obtained nanostructures. It was observed that the TiO2 nanoparticles prepared using hydrothermal method were highly crystalline and possess higher band gap value, even when same conditions of temperature, pressure, precursor ratios and solvent amount was kept constant while synthesizing TiO2 nanostructures via sol-gel method. The obvious effect of porous morphology exhibited by TiO2 nanoparticles prepared using hydrothermal route is reflected in its decolorization performance whereby 92.5% of the RB dye solution was degraded in 70 min of irradiation time.

  20. TiO2 impregnated graphene nanostructures: An effectual photocatalysts for water remediation application

    NASA Astrophysics Data System (ADS)

    Rakkesh, R. Ajay; Durgalakshmi, D.; Balakumar, S.

    2015-06-01

    In this work, we describe the fabrication of nanohybrid TiO2 impregnated Graphene nanostructures by modified Hummer's method. The chemically impregnated TiO2-Graphene hybrid nanostructures drastically enhanced their photodegradation activity of methylene blue (MB) dye in an aqueous medium compare to pure TiO2 nanoparticles. The enhancement in the photocatalytic activity was ascribed by a heterojunction between TiO2-Graphene interfaces. It remarkably decreased the recombination rate and likewise increased the number of holes participating in the photodegradation process, confirmed by XPS analysis. This study can provide a new insight for constructing the hybrid photocatalysts, which can be used in environmental pollution and water treatment applications.

  1. Mussel-Directed Synthesis of Nitrogen-Doped Anatase TiO2.

    PubMed

    Xie, Jingjing; Xie, Hao; Su, Bao-Lian; Cheng, Yi-Bing; Du, Xiaodong; Zeng, Hui; Wang, Menghu; Wang, Weimin; Wang, Hao; Fu, Zhengyi

    2016-02-24

    Structure-forming processes leading to biominerals are well worth learning in pursuit of new synthetic techniques. Strategies that attempt to mimic nature in vitro cannot replace an entire complex natural organism, requiring ingenuity beyond chemists' hands. A "bioprocess-inspired synthesis" is demonstrated for fabrication of N-doped TiO2 materials at ambient temperature by direct implantation of precursor into living mussels. The amorphous precursor transforms into N-doped anatase TiO2 with a hierarchical nanostructure. Synthetic TiO2 exhibits high phase stability and enhanced visible-light photocatalytic activity as a result of modifications to its band gap during in vivo mineralization. Intracellular proteins were found to be involved in TiO2 mineralization. Our findings may inspire material production by new synthetic techniques, especially under environmentally benign conditions.

  2. Microbicidal activity of TiO2 nanoparticles synthesised by sol-gel method.

    PubMed

    Priyanka, Karathan Parakkandi; Sukirtha, Thiruvangium Henry; Balakrishna, Kagalagodu Manjunthiah; Varghese, Thomas

    2016-04-01

    In this study, the authors investigated antimicrobial activity of TiO2 nanoparticles (NPs) synthesised by sol-gel method. As synthesised TiO2 NPs were characterised by X-ray diffraction, scanning electron microscopy and ultraviolet-visible absorption spectroscopy. The antimicrobial activity of calcined TiO2 nanoparticle samples was examined in day light on Gram positive bacteria (Staphylococcus aureus, Streptococcus pneumonia and Bacillus subtilis), Gram negative bacteria (Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli) and fungal test pathogen Candida albicans. The synthesised TiO2 NPs were found to be effective in visible light against Streptococcus pneumonia, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Candida albicans. PMID:27074858

  3. Room-Temperature Ferromagnetism in TiO2 Nanocrystals Synthesized by the Controlled Hydrolysis Procedure.

    PubMed

    Gu, Deen; Sun, Zhanhong; Zhou, Lv; Hu, Yongda; Jiang, Yadong

    2016-03-01

    TiO2 nanocrystals were prepared by a controlled hydrolysis procedure at room temperature. The effect of V-doping, N-doping and V/N codoping on the lattice parameters and magnetic properties of TiO2 nanocrystals was investigated by means of X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and vibration sample magnetometry. Doping performed at room temperature causes the expansion of lattice parameters. Undoped and doped TiO2 nanocrystals show room-temperature ferromagnetism. A monotonic correlation between saturation magnetization and the ratio of the lattice parameter c to a (c/a) was observed. Saturation magnetization of TiO2 nanocrystals increases with the value of c/a.

  4. Pulsed electric field assisted sol-gel preparation of TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Mani, Rajaboopathi; Han, Bing; Louhi-Kultanen, Marjatta

    2016-10-01

    This work studies the effect of a pulsed electric field (PEF) on the precipitation and properties of TiO2 nanoparticles. TiO2 nanoparticles were prepared using pulsed DC electric field assisted sol-gel method. The duration of the PEF treatment was varied to investigate its effect on the particle size of TiO2 nanoparticles. The nanoparticles were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, UV diffuse reflectance spectroscopy (UV-DRS) and transmission electron microscopy (TEM). It was found that TiO2 particles prepared with pulsed electric field assisted sol-gel method had enhanced average crystallite size due to the effect of the pulsed electric field on primary nucleation. The effect of electric field on nanoparticle preparation is interesting which can be used to control the grain and crystallite size of nanoparticle.

  5. Directed synthesis of hierarchical nanostructured TiO2 catalysts and their morphology-dependent photocatalysis for phenol degradation.

    PubMed

    Liu, Lu; Liu, Huajie; Zhao, Ya-Ping; Wang, Yuqiu; Duan, Yueqin; Gao, Guandao; Ge, Ming; Chen, Wei

    2008-04-01

    Nanostructured TiO2 with different hierarchical morphologies were synthesized via a warmly hydrothermal route. The properties of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption, UV-vis spectroscopy, etc. Two of the products, TiO2 1D nanorods (one-dimensional rutile TiO2 nanorods) and TiO2 3D0D microspheres (three-dimensional anatase TiO2 nanoparticle-assembled microspheres) exhibited superior photocatalytic effects on phenol degradation under UV illumination, compared with TiO2 3D1D microspheres (three-dimensional rutile TiO2 nanorods-assembled microspheres). Moreover, TiO2 3D0D was superior to TiO2 1D, as indicated by a 30% higher mineralization of dissolved phenol. Dihydroxybenze, 4,4'-dihydroxybiphenyl, benzoquinone, maleic anhydride, etc. were identified as the degradation intermediates. The excellent catalytic effect was attributed to the structural features of TiO2 1D nanorods and TiO2 3D0D microspheres, that is, a larger amount of surface active sites and a higher band gap energy resulted in more efficient decomposition of organic contaminants. PMID:18504963

  6. Directed synthesis of hierarchical nanostructured TiO2 catalysts and their morphology-dependent photocatalysis for phenol degradation.

    PubMed

    Liu, Lu; Liu, Huajie; Zhao, Ya-Ping; Wang, Yuqiu; Duan, Yueqin; Gao, Guandao; Ge, Ming; Chen, Wei

    2008-04-01

    Nanostructured TiO2 with different hierarchical morphologies were synthesized via a warmly hydrothermal route. The properties of the products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption, UV-vis spectroscopy, etc. Two of the products, TiO2 1D nanorods (one-dimensional rutile TiO2 nanorods) and TiO2 3D0D microspheres (three-dimensional anatase TiO2 nanoparticle-assembled microspheres) exhibited superior photocatalytic effects on phenol degradation under UV illumination, compared with TiO2 3D1D microspheres (three-dimensional rutile TiO2 nanorods-assembled microspheres). Moreover, TiO2 3D0D was superior to TiO2 1D, as indicated by a 30% higher mineralization of dissolved phenol. Dihydroxybenze, 4,4'-dihydroxybiphenyl, benzoquinone, maleic anhydride, etc. were identified as the degradation intermediates. The excellent catalytic effect was attributed to the structural features of TiO2 1D nanorods and TiO2 3D0D microspheres, that is, a larger amount of surface active sites and a higher band gap energy resulted in more efficient decomposition of organic contaminants.

  7. Efficient solar photocatalytic activity of TiO2 coated nano-porous silicon by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Sampath, Sridhar; Maydannik, Philipp; Ivanova, Tatiana; Shestakova, Marina; Homola, Tomáš; Bryukvin, Anton; Sillanpää, Mika; Nagumothu, Rameshbabu; Alagan, Viswanathan

    2016-09-01

    In the present study, TiO2 coated nano-porous silicon (TiO2/PS) was prepared by atomic layer deposition (ALD) whereas porous silicon was prepared by stain etching method for efficient solar photocatalytic activity. TiO2/PS was characterized by FESEM, AFM, XRD, XPS and DRS UV-vis spectrophotometer. Absorbance spectrum revealed that TiO2/PS absorbs complete solar light with wave length range of 300 nm-800 nm and most importantly, it absorbs stronger visible light than UV light. The reason for efficient solar light absorption of TiO2/PS is that nanostructured TiO2 layer absorbs UV light and nano-porous silicon layer absorbs visible light which is transparent to TiO2 layer. The amount of visible light absorption of TiO2/PS directly increases with increase of silicon etching time. The effect of silicon etching time of TiO2/PS on solar photocatalytic activity was investigated towards methylene blue dye degradation. Layer by layer solar absorption mechanism was used to explain the enhanced photocatalytic activity of TiO2/PS solar absorber. According to this, the photo-generated electrons of porous silicon will be effectively injected into TiO2 via hetero junction interface which leads to efficient charge separation even though porous silicon is not participating in any redox reactions in direct.

  8. Study of TiO2 nanomembranes obtained by an induction heated MOCVD reactor

    NASA Astrophysics Data System (ADS)

    Crisbasan, A.; Chaumont, D.; Sacilotti, M.; Crisan, A.; Lazar, A. M.; Ciobanu, I.; Lacroute, Y.; Chassagnon, R.

    2015-12-01

    Nanostructures of TiO2 were grown using the metal oxide chemical vapor deposition (MOCVD) technique. The procedure used induction heating on a graphite susceptor. This specific feature and the use of cobalt and ferrocene catalysts resulted in nanomembranes never obtained by common MOCVD reactors. The present study discusses the preparation of TiO2 nanomembranes and the dependence of nanomembrane structure and morphology on growth parameters.

  9. Kinetics and mechanism of photolysis and TiO2 photocatalysis of triclosan.

    PubMed

    Son, Hyun-Seok; Ko, Gwangpyo; Zoh, Kyung-Duk

    2009-07-30

    The degradations of triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol), a potent broad-spectrum antimicrobial agent, were compared in TiO2-only in the dark condition, photolysis, and TiO2 photocatalysis with a UV-A lamp. TiO2 photocatalysis more effectively degraded and mineralized triclosan compared to TiO2-only and photolysis conditions. While triclosan removed only 30% by TiO2-only condition within 20 min, the triclosan degradation in photolysis and photocatalysis at the same time was 75 and 82%, respectively, and TOC removal was significantly higher in photocatalysis than in photolysis. The data of kinetics showed that triclosan adsorption onto TiO2 was fitted to Langmuir isotherm, and TiO2 photocatalysis was fitted to Langmuir-Hinshelwood model (b=27.99 mM(-1), K(triclosan)=9.49 mM(-1)). The neutral range of pH was favorable to photocatalysis due to the charge effect between TiO2 and triclosan. The addition of 2-propanol, a radical scavenger, significantly reduced the degradation of triclosan both in photolysis and photocatalysis. Dioxin-type intermediates such as dibenzo-dichloro-p-dioxin (DCDD), dibenzo-p-dioxin were produced in photolysis with and without 2-propanol, and also in photocatalysis with 2-propanol, but these intermediates were not detected in photocatalysis without 2-propanol. This result indicates that the photocatalytic degradation of triclosan is mainly achieved by radicals, and these radicals can further degrade dioxin-type intermediates once they are produced in photocatalysis.

  10. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability.

  11. Photocatalytic degradation of acetaminophen in modified TiO2 under visible irradiation.

    PubMed

    Dalida, Maria Lourdes P; Amer, Kristine Marfe S; Su, Chia-Chi; Lu, Ming-Chun

    2014-01-01

    This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO2) solution under a visible light (λ >440 nm). The TiO2 photocatalyst used in this study was synthesized via sol-gel method and doped with potassium aluminum sulfate (KAl(SO4)2) and sodium aluminate (NaAlO2). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO2 catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO2/KAl(SO4)2, 95% removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO2/KAl(SO4)2 presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO2/NaAlO2 photocatalyst showed low photocatalytic degradation than TiO2/KAl(SO4)2. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO2/KAl(SO4)2 at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased.

  12. Synthesis, characterization, and photocatalytic activity of TiO(2-x)N(x) nanocatalyst.

    PubMed

    Wang, Y Q; Yu, X J; Sun, D Z

    2007-06-01

    Nitrogen-doped titanium dioxide powders were prepared by wet method, that is, the hydrolysis of acidic tetra-butyl titanate using aqueous ammonia solution, followed by calcination at temperatures about 350 degrees C. The catalysts exhibited photocatalytic activity in the visible light region owing to N-doping. The light absorption onset of TiO(2-x)N(x) was shifted to the visible region at 459 nm compared to 330 nm of pure TiO(2). An obvious decrease in the band gap was observed by the optical absorption spectroscopy, which resulted from N2p localized states above the valence band of TiO(2-x)N(x) (compared to TiO(2)). The TiO(2-x)N(x) catalyst was characterized to be anatase with oxygen-deficient stoichiometry by X-ray diffraction (XRD), surface photovoltage spectroscopy (SPS) and X-ray photoelectron spectroscopy (XPS). The binding energy of N1s measured by XPS characterization was 396.6 eV (TiN bonds, beta-N) and 400.9 eV (NN bonds, gamma-N(2)), respectively. The photocatalytic activity of TiO(2-x)N(x) under visible light was induced by the formation of beta-N in the structure. Photocatalytic decomposition of benzoic acid solutions was carried out in the ultraviolet and visible (UV-vis) light region, and the TiO(2-x)N(x) catalyst showed higher activity than pure TiO(2). PMID:17116365

  13. Characterization and improved solar light activity of vanadium doped TiO2/diatomite hybrid catalysts.

    PubMed

    Wang, Bin; Zhang, Guangxin; Leng, Xue; Sun, Zhiming; Zheng, Shuilin

    2015-03-21

    V-doped TiO2/diatomite composite photocatalysts with different vanadium concentrations were synthesized by a modified sol-gel method. The diatomite was responsible for the well dispersion of TiO2 nanoparticles on the matrix and consequently inhibited the agglomeration. V-TiO2/diatomite hybrids showed red shift in TiO2 absorption edge with enhanced absorption intensity. Most importantly, the dopant energy levels were formed in the TiO2 bandgap due to V(4+) ions substituted to Ti(4+) sites. The 0.5% V-TiO2/diatomite photocatalyst displayed narrower bandgap (2.95 eV) compared to undoped sample (3.13 eV) and other doped samples (3.05 eV) with higher doping concentration. The photocatalytic activities of V doped TiO2/diatomite samples for the degradation of Rhodamine B under stimulated solar light illumination were significantly improved compared with the undoped sample. In our case, V(4+) ions incorporated in TiO2 lattice were responsible for increased visible-light absorption and electron transfer to oxygen molecules adsorbed on the surface of TiO2 to produce superoxide radicals ˙O2(-), while V(5+) species presented on the surface of TiO2 particles in the form of V2O5 contributed to e(-)-h(+) separation. In addition, due to the combination of diatomite as support, this hybrid photocatalyst could be separated from solution quickly by natural settlement and exhibited good reusability. PMID:25497036

  14. Bacterial responses to Cu-doped TiO(2) nanoparticles.

    PubMed

    Wu, Bing; Huang, Rick; Sahu, Manoranjan; Feng, Xueyang; Biswas, Pratim; Tang, Yinjie J

    2010-03-01

    The toxicity of Cu-doped TiO(2) nanoparticles (NPs, 20nm), synthesized by a flame aerosol reactor, to Mycobacterium smegmatis and Shewanella oneidensis MR-1, is the primary focus of this study. Both doped and non-doped TiO(2) NPs (20nm) tended to agglomerate in the medium solution, and therefore did not penetrate into the cell and damage cellular structures. TiO(2) particles (<100mg/L) did not apparently interfere with the growth of the two species in aqueous cultures. Cu-doped TiO(2) NPs (20mg/L) significantly reduced the M. smegmatis growth rate by three fold, but did not affect S. oneidensis MR-1 growth. The toxicity of Cu-doped TiO(2) NPs was driven by the release of Cu(2+) from the parent NPs. Compared to equivalent amounts of Cu(2+), Cu-doped TiO(2) NPs exhibited higher levels of toxicity to M. smegmatis (P-value<0.1). Addition of EDTA in the culture appeared to significantly decrease the anti-mycobacterium activity of Cu-doped TiO(2) NPs. S. oneidensis MR-1 produced a large amount of extracellular polymeric substances (EPS) under NP stress, especially extracellular protein. Therefore, S. oneidensis MR-1 was able to tolerate a much higher concentration of Cu(2+) or Cu-doped TiO(2) NPs. S. oneidensis MR-1 also adsorbed NPs on cell surface and enzymatically reduced ionic copper in culture medium with a remediating rate of 61microg/(liter x OD(600) x hour) during its early exponential growth phase. Since the metal reducing Shewanella species can efficiently "clean" metal-oxide NPs, the activities of such environmentally relevant bacteria may be an important consideration for evaluating the ecological risk of metal-oxide NPs. PMID:19931887

  15. Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment.

    PubMed

    Ide, Yusuke; Inami, Nozomu; Hattori, Hideya; Saito, Kanji; Sohmiya, Minoru; Tsunoji, Nao; Komaguchi, Kenji; Sano, Tsuneji; Bando, Yoshio; Golberg, Dmitri; Sugahara, Yoshiyuki

    2016-03-01

    Although tremendous effort has been directed to synthesizing advanced TiO2 , it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase-rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2 , which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2 , inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective.

  16. Efficient removal of toluene and benzene in gas phase by the TiO2/Y-zeolite hybrid photocatalyst.

    PubMed

    Takeuchi, Masato; Hidaka, Manabu; Anpo, Masakazu

    2012-10-30

    Efficient removal of toluene or benzene molecules thinly diffused in gas phase was achieved by using TiO(2)/Y-zeolite hybrid photocatalysts. TiO(2) of 10 wt% hybridized with a hydrophobic USY zeolite showed higher photocatalytic reactivity as compared to TiO(2) hybridized with hydrophilic H-Y or Na-Y zeolites. This phenomenon can be explained by the fact that the hydrophobic USY zeolite efficiently adsorbs the organic compounds and smoothly supplies them onto the TiO(2) photocatalyst surface. However, the toluene or benzene molecules, which are strongly trapped on the hydrophilic H(+) or Na(+) sites of zeolite, cannot diffuse onto the TiO(2) surfaces, resulting in lower photocatalytic reactivity. Although the adsorption capacity of the pure TiO(2) sample rapidly deteriorated, the TiO(2)/Y-zeolite hybrid system maintained a high adsorption efficiency to remove such aromatic compounds for a long period. PMID:22947182

  17. Structural and optical properties of terbium in TiO 2 matrix

    NASA Astrophysics Data System (ADS)

    Domaradzki, Jaroslaw; Prociow, Eugeniusz L.; Kaczmarek, Danuta; Borkowska, Agnieszka; Berlicki, Tadeusz; Prociow, Krystyna

    2009-07-01

    TiO 2 thin films doped with different concentration of Tb have been prepared and study of terbium photoluminescence in TiO 2 host has been presented. Thin films were deposited on silicon and SiO 2 substrates by magnetron sputtering of Ti-Tb mosaic target in oxygen atmosphere. XRD examinations show nanocrystalline nature of prepared thin films with TiO 2-anatase and -rutile phases depending on concentration of Tb. Optical transmission study has shown the red shift of the fundamental absorption edge of TiO 2 with the increase of terbium content in the thin film. Also, the transparency decreased with increasing in amount of Tb. Photoluminescence (PL) spectra, measured upon UV excitation at 302 nm at room temperature, show a dominating green luminescence corresponding to 5D 4- 7F 5 transition at 545 nm for TiO 2-rutile thin film with 2.6 at.% of Tb. The superposition of PL peaks from Tb and TiO 2 host matrix was also observed at 491 nm.

  18. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    PubMed Central

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion. PMID:27215703

  19. Facile synthesis of porous TiO2 nanospheres and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Huang, Jiarui; Ren, Haibo; Liu, Xiaosi; Li, Xuexue; Shim, Jae-Jin

    2015-05-01

    Uniform and monodisperse porous TiO2 nanospheres were synthesized by a hydrothermal method. Techniques of X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption, UV-vis absorption spectroscopy, and transmission electron microscopy were used to characterize the structure and morphology of the products. The BET surface area of the porous TiO2 nanospheres was calculated to be 26.1 cm2 g-1. In addition, the obtained porous TiO2 nanospheres were used as catalyst to photodegrade methylene blue, Rhodamine B, methyl orange, p-nitrophenol, and eosin B. Compared to commercial TiO2 powder, the as-prepared porous TiO2 nanospheres exhibited higher catalytic activities due to their large surface areas and porous nanostructures. The photocatalytic reaction rate constant of the porous TiO2 nanospheres in photocatalytic decomposition of methylene blue and Rhodamine B under simulated solar light were calculated as 0.0545 min-1 and 0.0579 min-1, respectively. Moreover, the catalyst was demonstrated to have good stability and reusability.

  20. Superhydrophilic graphene-loaded TiO2 thin film for self-cleaning applications.

    PubMed

    Anandan, Srinivasan; Rao, Tata Narasinga; Sathish, Marappan; Rangappa, Dinesh; Honma, Itaru; Miyauchi, Masahiro

    2013-01-01

    We develop a simple approach to fabricate graphene-loaded TiO(2) thin films on glass substrates by the spin-coating technique. Our graphene-loaded TiO(2) films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO(2) films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO(2) film. The enhanced photocatalytic activity of graphene/TiO(2) films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO(2) to graphene. The electroconductivity of the graphene-loaded TiO(2) thin film also contributes to the self-cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency. The promising characteristics of (inexpensive, transparent, conductive, superhydrophilic, and highly photocatalytically active) graphene-loaded TiO(2) films may have the potential use in various indoor applications.

  1. Location Of Hole And Electron Traps On Nanocrystalline Anatase TiO2

    SciTech Connect

    Mercado, Candy C.; Knorr, Fritz J.; McHale, Jeanne L.; Usmani, Shirin M.; Ichimura, Andrew S.; Saraf, Laxmikant V.

    2012-05-17

    The defect photoluminescence from TiO2 nanoparticles in the anatase phase is reported for nanosheets which expose predominantly (001) surfaces, and compared to that from conventional anatase nanoparticles which expose mostly (101) surfaces. Also reported is the weak defect photoluminescence of TiO2 nanotubes, which we find using electron back-scattered diffraction to consist of walls which expose (110) and (100) facets. The nanotubes exhibit photoluminescence that is blue-shifted and much weaker than that from conventional TiO2 nanoparticles. Despite the preponderance of (001) surfaces in the nanosheet samples, they exhibit photoluminescence similar to that of conventional nanoparticles. We assign the broad visible photoluminescence of anatase nanoparticles to two overlapping distributions: hole trap emission associated with oxygen vacancies on (101) exposed surfaces, which peaks in the green, and a broader emission extending into the red which results from electron traps on under-coordinated titanium atoms, which are prevalent on (001) facets. The results of this study suggest how morphology of TiO2 nanoparticles could be optimized to control the distribution and activity of surface traps. Our results also shed light on the mechanism by which the TiCl4 surface treatment heals traps on anatase and mixed-phase TiO2 films, and reveals distinct differences in the trap-state distributions of TiO2 nanoparticles and nanotubes. The molecular basis for electron and hole traps and their spatial separation on different facets is discussed.

  2. Micropatterning of TiO2 Thin Films by MOCVD and Study of Their Growth Tendency

    PubMed Central

    Hwang, Ki-Hwan; Kang, Byung-Chang; Jung, Duk Young; Kim, Youn Jea; Boo, Jin-Hyo

    2015-01-01

    In this work, we studied the growth tendency of TiO2 thin films deposited on a narrow-stripe area (<10 μm). TiO2 thin films were selectively deposited on OTS patterned Si(100) substrates by MOCVD. The experimental data showed that the film growth tendency was divided into two behaviors above and below a line patterning width of 4 μm. The relationship between the film thickness and the deposited area was obtained as a function of f(x) = a[1 − e(−bx)]c. To find the tendency of the deposition rate of the TiO2 thin films onto the various linewidth areas, the relationship between the thickness of the TiO2 thin film and deposited linewidth was also studied. The thickness of the deposited TiO2 films was measured from the alpha-step profile analyses and cross-sectional SEM images. At the same time, a computer simulation was carried out to reveal the relationship between the TiO2 film thickness and deposited line width. The theoretical results suggest that the mass (velocity) flux in flow direction is directly affected to the film thickness. PMID:25799219

  3. Controllable hydrothermal synthesis, optical and photocatalytic properties of TiO2 nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Yanyan; Zhang, Maocui; Zhang, Miao; Lv, Jianguo; Jiang, Xishun; He, Gang; Song, XuePing; Sun, Zhaoqi

    2014-10-01

    Different surface morphologies of TiO2 thin films were prepared by hydrothermal synthesis method on Ti substrates through changing reaction time. The microstructure, composition, optical properties and photocatalytic properties of TiO2 thin films were systematically investigated by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectrometer and ultraviolet-visible spectroscopy. As the reaction time increases, anatase structure and brookite structure of TiO2 films respectively increases and decreases, corresponding to surface morphology changes from irregular structure to regular geometrical shape structure. These structural changes are accompanied by significant variations of optical properties and photocatalytic properties including a widening of the band gap from 2.86 to 3.19 eV, photocatalytic degradation efficiency from 92.5 to 98.1% and photocatalytic degradation rate from 0.032 to 0.048 min-1. Among all samples, TiO2-1 shows the best photocatalytic properties. Compositional analysis indicates that TiO2 surface layer contains Ti and O elements, the ratio of Ti:O is 1:2.28 which is close to the atom ratio of TiO2.

  4. Photoluminescence studies of nitrogen-doped TiO2 powders prepared by annealing with urea

    NASA Astrophysics Data System (ADS)

    Kawai, T.; Kishimoto, Y.; Kifune, K.

    2012-11-01

    Photoluminescence and excitation spectra have been investigated for undoped and nitrogen-doped TiO2 powders at low temperatures. A broad luminescence band peaking at 2.25 eV is observed in the undoped TiO2 powders. The 2.25 eV luminescence band exhibits a sharp rise from 3.34 eV in the excitation spectrum reflecting the fundamental absorption edge of anatase TiO2. On the other hand, the N-doped TiO2 powders obtained by annealing with urea at 350 and 500°C exhibit broad luminescence bands around 2.89 and 2.63 eV, respectively. The excitation spectra for these luminescence bands rise from the lower energy side of the fundamental absorption edge of anatase TiO2. The origin of the luminescence bands and N-related energy levels formed in the band-gap of TiO2 are discussed.

  5. Photoactive TiO2 coatings obtained by Plasma Electrolytic Oxidation in refrigerated electrolytes

    NASA Astrophysics Data System (ADS)

    Franz, Silvia; Perego, Daniele; Marchese, Ottavia; Lucotti, Andrea; Bestetti, Massimiliano

    2016-11-01

    The effect of synthesis conditions on the properties of nanoporous TiO2 coatings obtained by PEO in refrigerated electrolytes have been investigated. Linear sweep voltammetry was carried out on the TiO2 coatings, in dark and under UV-C irradiation, in order to assess the photoelectrochemical behavior of samples. The largest photocurrents (0.18 mA/cm2) were measured on TiO2 coatings obtained by PEO in refrigerated aqueous solutions. UV-vis spectra revealed that lowering the processing temperature from 20 to -3.5 °C induced a blue-shift of the absorption band of the TiO2 coatings from 3.05 to 3.42 eV. The main advantage of PEO in refrigerated aqueous solutions over current approaches, based on anodic oxidation and thermal treatments, is that the synthesis of photoactive TiO2 coatings can be carried out in a relatively easy, quick and reproducible way, without annealing pre- and post-treatments. Furthermore, by controlling the solution temperature in PEO process, the photocurrent of the resulting TiO2 coating reaches quite high values.

  6. Charge transfer in photorechargeable composite films of TiO2 and polyaniline

    NASA Astrophysics Data System (ADS)

    Nomiyama, Teruaki; Sasabe, Kenichi; Sakamoto, Kenta; Horie, Yuji

    2015-07-01

    A photorechargeable battery (PRB) is a photovoltaic device having an energy storage function in a single cell. The photoactive electrode of PRB is a bilayer film consisting of bare porous TiO2 and a TiO2-polyaniline (PANi) mixture that work as a photovoltaic current generator and an electrochemical energy storage by ion dedoping, respectively. To study the charge transfer between TiO2 and PANi, the photorechargeable quantum efficiency QE ([electron count on discharge]/[incident photon count on photocharge]) was measured by varying the thickness LS of the TiO2-PANi mixture. The quantum efficiency QEuv for UV photons had a maximum of ˜7% at LS ˜ 7 µm. The time constant τTP for the charge transfer was about 10-1 s, which was longer ten times or more than the lifetime of excited electrons within TiO2. These facts reveal that the main rate-limiting factor in the photocharging process is the charge transfer between TiO2 and PANi.

  7. Photocatalytic Oxidation of Volatile Organic Compounds Over Electrospun Activated TIO2/CARBON Nanofiber Composite

    NASA Astrophysics Data System (ADS)

    Gholamvand, Zahra; Aboutalebi, Seyed Hamed; Keyanpour-Rad, Mansoor

    In this study, TiO2/PAN-based fibers were prepared by electrospinning a composite solution containing both the desirable contents of TiO2 and a 10 wt. % PAN polymer solution dissolved in N, N-dimethylformamide. The TiO2 loaded electrospun PAN nanofibers were then carbonized at 1000 °C in N2 atmosphere furnace after stabilization at 230 °C in air. Then CNF/TiO2 nanofibers were oxidized at 450 °C in air. The morphology and structure of the TiO2-embeded carbon nanofibers were investigated by SEM and Raman spectroscopy. Specific surface area was determined using BET equation from N2 adsorption analysis. Photocatalytic tests were conducted in a UV illuminated set-up specialized for the filters using ethanol vapor. The results have shown that ethanol vapor was efficiently degraded on TiO2/CNF composite nanofiber mat under UV illumination. The aim of this study was to further investigate the feasibility of TiO2/ACF for practical indoor air purification.

  8. Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

    NASA Astrophysics Data System (ADS)

    Madusanka, Nadeesh; Shivareddy, Sai G.; Hiralal, Pritesh; Eddleston, Mark D.; Choi, Youngjin; Oliver, Rachel A.; Amaratunga, Gehan A. J.

    2016-05-01

    A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO2. The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO2/CRS nanofilms on SiO2/Si wafers were used to form metal-insulator-metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz-1 MHz were measured. At 1 kHz CRS-TiO2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO2 respectively, significantly higher than reported values of pure CRS (21), TiO2 (41) and other dielectric polymer-TiO2 nanocomposite films. Furthermore, all three CRS-TiO2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10-6-10-7 A cm-2). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported.

  9. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays.

    PubMed

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion. PMID:27215703

  10. Degradability of Treated Ethion Insecticide by TiO2 Photocatalysis.

    PubMed

    Hassarangsee, Siriporn; Uthaibutra, Jamnong; Nomura, Nakao; Whangchai, Kanda

    2015-01-01

    Ethion, an insecticide, is widely used with fruit and vegetable crops. This research studied the reduction and oxidative degradation of standard ethion by TiO2 photocatalysis. A standard ethion solution (1 mg L(-1)) was treated with different concentrations of TiO2 powder (5, 10, 20, 40 and 60 mg mL(-1)) for 0, 15, 30, 45 and 60 min. The amount of ethion residue was detected by gas chromatography with flame photometric detection (GC-FPD) and the concentration of anions produced as major degradation products was determined by Ion Chromatography (IC). The TiO2 photocatalysis efficiently reduced ethion concentrations, with the highest degradation rate occurring within the first 15 min of reaction. The reaction produced sulphate and phosphate anions. The TiO2photocatalysis reduced 1 mg L(-1) ethion to 0.18 mg L(-1) when treated with 60 mg mL(-1) TiO2 powder for 60 min. The lethal concentration (LC50) of standard ethion was also estimated and compared to the treated ethion. All treatments, especially 60 mg mL(-1) TiO2 powder, markedly detoxified ethion, as tested with brine shrimp (Artemia salina L.), with an LC50 value of 765.8 mg mL(-1), compared to the control of 1.01 mg mL(-1). PMID:26353413

  11. Bifunctional ultraviolet/ultrasound responsive composite TiO2/polyelectrolyte microcapsules.

    PubMed

    Gao, Hui; Wen, Dongsheng; Tarakina, Nadezda V; Liang, Jierong; Bushby, Andy J; Sukhorukov, Gleb B

    2016-03-01

    Designing and fabricating multifunctional microcapsules are of considerable interest in both academic and industrial research aspects. This work reports an innovative approach to fabricate composite capsules with high UV and ultrasound responsive functionalities that can be used as external triggers for controlled release, yet with enhanced mechanical strength that can make them survive in a harsh environment. Needle-like TiO2 nanoparticles (NPs) were produced in situ into layer-by-layer (LbL) polyelectrolyte (PE) shells through the hydrolysis of titanium butoxide (TIBO). These rigid TiO2 NPs yielded the formed capsules with excellent mechanical strength, showing a free standing structure. A possible mechanism is proposed for the special morphology formation of the TiO2 NPs and their reinforcing effects. Synergistically, their response to UV and ultrasound was visualized via SEM, with the results showing an irreversible shell rapture upon exposure to either UV or ultrasound irradiation. As expected, the release studies revealed that the dextran release from the TiO2/PE capsules was both UV-dependent and ultrasound-dependent. Besides, the biocompatibility of the capsules with the incorporation of amorphous TiO2 NPs was confirmed by an MTT assay experiment. All these pieces of evidence suggested a considerable potential medicinal application of TiO2/PE capsules for controlled drug delivery. PMID:26878702

  12. Exposure to TiO2 nanoparticles increases Staphylococcusaureusinfection of HeLa cells

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Wei, Ming-Tzo; Walker, Stephen. G.; Wang, Hong Zhan; Gondon, Chris; Brink, Peter; Guterman, Shoshana; Zawacki, Emma; Applebaum, Eliana; Rafailovich, Miriam; Ou-Yang, H. Daniel; Mironava, Tatsiana

    TiO2 is one of the most common nanoparticles in industry from food additives to energy generation. Even though TiO2 is also used as an anti-bacterial agent in combination with UV, we found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles largely increased their risk of bacterial invasion. HeLa cells cultured with low dosage rutile and anatase TiO2 nanoparticles (0.1 mg/ml) for 24 hrs prior to exposure to bacteria had 350% and 250% respectively more bacteria infected per cell. The increase was attributed to increased LDH leakage, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40% fewer bacteria, further increasing the risk of infection. In combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.

  13. Spherical TiO2 aggregates with different building units for dye-sensitized solar cells.

    PubMed

    Liu, Zhaohui; Su, Xunjia; Hou, Genliang; Bi, Song; Xiao, Zhou; Jia, Haipeng

    2013-09-01

    Tailoring the architectures of spherical TiO2 aggregates is crucial to obtain superior photovoltaic properties and promote their application in dye-sensitized solar cells (DSSCs). Herein, we synthesized spherical TiO2 aggregates using different building units, including nanocrystallites, nanorods, nanosheets, and nanotubes, via a hydrothermal method, and studied the effect of the building units on the performances of DSSCs. The aggregates assembled by uniform nanosheet and nanotube building units were synthesized with the use of spherical TiO2 nanorod aggregates as titanium sources in an alkaline hydrothermal reaction. Compared with TiO2 nanoparticles, the spherical TiO2 aggregates possess higher surface area, more efficient light scattering ability, and better electron transport properties. Among the four types of spherical TiO2 aggregates; the nanorod, nanotube, and nanosheet aggregates demonstrate better electron transport properties than the nanocrystallite aggregates; the nanotube and nanosheet aggregates exhibit more efficient light scattering than the nanocrystallite and nanorod aggregates; and the nanotube aggregates show the highest surface area. Thus the DSSC based on nanotube aggregates exhibited the highest energy conversion efficiency of 7.48%, which is 16.0%, 9.7%, and 19.5% higher than those of the DSSCs based on the nanosheet, nanorod, and nanocrystallite aggregates, respectively.

  14. Self-cleaning and mechanical properties of modified white cement with nanostructured TiO2.

    PubMed

    Khataee, R; Heydari, V; Moradkhannejhad, L; Safarpour, M; Joo, S W

    2013-07-01

    In the present study, self-cleaning and mechanical properties of white Portland cement by addition of commercial available TiO2 nanoparticles with the average particle size of 80 nm were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET were used to characterize TiO2 nanoparticles. For determination of self-cleaning properties of TiO2-modified white cement, colorimetric tests in decolorization of C.I. Basic Red 46 (BR46) in comparison to unmodified cement samples was applied. The results indicated that with increasing the amount of TiO2 nanoparticles in modified cement, self-cleaning property of the samples increased. The mechanical properties of TiO2-modified and unmodified cement samples, such as time of setting of hydraulic cement, compressive strength of hydraulic cement mortar and flexural strength of hydraulic cement mortar were examined. The results indicated that addition of TiO2 nanoparticles up to maximum replacement level of 1.0% improved compressive and flexural strength and decreased its setting time.

  15. Structure and high photocatalytic activity of (N, Ta)-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Le, N. T. H.; Thanh, T. D.; Pham, V.-T.; Phan, T. L.; Lam, V. D.; Manh, D. H.; Anh, T. X.; Le, T. K. C.; Thammajak, N.; Hong, L. V.; Yu, S. C.

    2016-10-01

    A hydrothermal method was used to prepare three nano-crystalline samples of TiO2 (S1), N-doped TiO2 (S2), and (N, Ta)-codoped TiO2 (S3) with average crystallite sizes (D) of 13-25 nm. X-ray diffraction studies confirmed a single phase of the samples with a tetragonal/anatase structure. A slight increase in the lattice parameters was observed when N and/or Ta dopants were doped into the TiO2 host lattice. Detailed analyses of extended X-ray absorption spectra indicated that N- and/or Ta-doping into TiO2 nanoparticles influenced the co-ordination number and radial distance (R) of Ti ions in the anatase structure. Concerning their absorption spectra, (N, Ta)-doping narrowed the band gap (Eg) of TiO2 from 3.03 eV for S1 through 2.94 eV for S2 to 2.85 eV for S3. Such results revealed the applicability of these nanoparticles in the photocatalytic field working in the ultraviolet (UV)-visible region. Among these, photocatalytic activity of S3 was the strongest. By using S3 as a catalyst powder, the degradation efficiency of methylene blue solution was about 99% and 93% after irradiation of UV-visible light for 75 min and visible-light for 180 min, respectively.

  16. Influence of silver doping on surface defect characteristics of TiO2

    NASA Astrophysics Data System (ADS)

    Tripathi, S. K.; Rani, Mamta

    2015-08-01

    In the present work, we proposed a novel silver doped TiO2 polyethylene conjugated films to improve the performance of DSSCs. Oxides nanoparticles dispersed in a semiconducting polymer form the active layer of a solar cell. Localized surface plasmon resonance effects associated with spatially dispersed silver (Ag) nanoparticles can be exploited to enhance the light-harvesting efficiency, the photocurrent density and the overall light-to electrical-energy-conversion efficiency of high-area DSSCs based TiO2 photoanodes. Silver doped titanium dioxide (TiO2:Ag) is prepared by sol-gel technique and deposited on fluorine doped indium oxide (FTO) coated glass substrates by using doctor blade technique at 550°C from aqueous solutions of titanium butoxide and silver nitrate precursors. The effect of Ag doping on electrical properties of films is studied. The Ag-TiO2 films are about 548 times more photosensitive as compare to the pure TiO2 sample. The presence of metallic Ag nanoparticles and oxygen vacancy on the surface of TiO2 nanoparticles promotes the separation of photogenerated electron-hole pairs and thus enhances the photosensitivity. Photoconduction mechanism of all prepared samples is investigated by performing transient photoconductivity measurements on TiO2 and Ag-TiO2 films keeping intensity of light constant.

  17. Equilibration Kinetics and Chemical Diffusion of Indium-Doped TiO2.

    PubMed

    Nowotny, Janusz; Alim, Mohammad A

    2015-04-30

    The present work reports the gas/solid equilibration kinetics for In-doped TiO2 (0.4 atom % In) at elevated temperatures (1023-1273 K) in the gas phase of controlled oxygen activity [10(-13) Pa < p(O2) < 10(5) Pa]. Thus, the determined chemical diffusion coefficient is considered in terms of a microdiffusion coefficient that is reflective of the transport kinetics within very narrow ranges of oxygen activities. In analogy to pure TiO2, the chemical diffusion coefficient for In-doped TiO2 exhibits a maximum at the n-p transition point. The activation energy of the chemical diffusion exhibits a decrease with temperature from 200 kJ/mol at 1023 K to an insignificant value at 1273 K. This effect is reflective of a segregation-induced electrical potential barrier blocking the transport of defects. The absolute value of the chemical diffusion coefficient for In-doped TiO2 is larger from that of pure TiO2 by a factor of approximately 10. The effect of indium on the diffusion rate is considered in terms of the associated concentration of oxygen vacancies, which are formed in order to satisfy the charge neutrality for In-doped TiO2.

  18. First-principles study on transition metal-doped anatase TiO2.

    PubMed

    Wang, Yaqin; Zhang, Ruirui; Li, Jianbao; Li, Liangliang; Lin, Shiwei

    2014-01-28

    The electronic structures, formation energies, and band edge positions of anatase TiO2 doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO2 were constructed by using the 24-atom 2 × 1 × 1 supercell of anatase TiO2 with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO2, lead to the improvement in the photoreactivity of TiO2, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO2 becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response.

  19. Phenol degradation by TiO2 photocatalysts combined with different pulsed discharge systems.

    PubMed

    Zhang, Yi; Lu, Jiani; Wang, Xiaoping; Xin, Qing; Cong, Yanqing; Wang, Qi; Li, Chunjuan

    2013-11-01

    Films of TiO2 nanotubes distributed over the inner surface of a discharge reactor cylinder (CTD) or adhered to a stainless steel electrode surface (PTD) in a discharge reactor were compared with a single-discharge (SD) system to investigate their efficiencies in phenol degradation. Morphology studies indicated that the TiO2 film was destroyed in the PTD system, but that there was no change in the CTD system after discharge. X-ray diffraction results revealed that the anatase phase of the original sample was preserved in the CTD system, but that an anatase-to-rutile phase transformation occurred in the PTD system after discharge. The highest efficiencies of phenol degradation and total organic carbon (TOC) mineralization were observed in the CTD system, and there was no decrease in phenol degradation efficiency upon reuse of a TiO2 film, indicating high catalysis activity and stability of the TiO2 photocatalysts in the combined treatment. TiO2 photocatalysts favored the formation of hydrogen peroxide and disfavored the formation of ozone. A greater degree of oxidation of intermediates and higher energy efficiency in phenol oxidation were observed with the TiO2-plasma systems, especially in the CTD system, compared to those with the SD system.

  20. Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

    NASA Astrophysics Data System (ADS)

    Madusanka, Nadeesh; Shivareddy, Sai G.; Hiralal, Pritesh; Eddleston, Mark D.; Choi, Youngjin; Oliver, Rachel A.; Amaratunga, Gehan A. J.

    2016-05-01

    A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO2. The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO2/CRS nanofilms on SiO2/Si wafers were used to form metal–insulator–metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz–1 MHz were measured. At 1 kHz CRS-TiO2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO2 respectively, significantly higher than reported values of pure CRS (21), TiO2 (41) and other dielectric polymer-TiO2 nanocomposite films. Furthermore, all three CRS-TiO2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10‑6–10‑7 A cm‑2). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported.

  1. The adsorption and photo-degradation of oxalic acid at the TiO2 surface.

    NASA Astrophysics Data System (ADS)

    Mendive, Cecilia; Blesa, Miguel; Bahnemann, Detlef

    2006-03-01

    Oxalic acid is the simplest model compound to study the heterogeneous photocatalytic oxidation of pollutants on TiO2 containing more than one carboxylate group. We have carried out a study of a system of an oxalic acid solution in contact with a thin film of TiO2 particles employing ATR - FTIR in combination with quantum chemical calculations. Thus, possible adsorption structures have been identified and molecular dynamic simulations have been used to compare their predictions with the experimental data. It was found that the adsorption of oxalic acid on TiO2 in the dark can be explained in terms of two surface complexation modes for the anatase phase and only one surface complexation mode for the rutile phase. We have found that under illumination one of the complexes on the anatase phase preferably undergoes photo-degradation. At the same time water molecules are desorbed from the TiO2 surface by a thermal mechanism induced by the absorption of photons. Both processes favor the adsorption of more molecules of oxalic acid at the TiO2 surface which is thus enriched in the second complexation mode. A similar mechanism was found to occur on the rutile phase. The only complexation mode appears not to be photo-sensitive but the TiO2 surface is enriched in oxalic acid under illumination due to the replacement of photo-desorbed water molecules.

  2. Preparation, performance and adsorption activity of TiO2 nanoparticles entrapped PVDF hybrid membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Wang, Yang; You, Yuting; Meng, Hao; Zhang, Jianghua; Xu, Xinxin

    2012-12-01

    The TiO2 nanoparticles entrapped poly(vinylidenefluoride) (PVDF) hybrid membranes were prepared through impregnating the pre-treated PVDF film in the TiO2 suspension. SEM, XRD, TG and ATR-IR analyses were used to character the hybrid membranes. The results showed that the TiO2 nanoparticles with average size about 44 nm were deposited on the surface and inner pores of PVDF films. The pre-treatment of PVDF with cetyltrimethyl ammonium bromide (CTAB) is benefit for TiO2loading. The ATR-IR spectra revealed that physical interaction played important role in the construction of hybrid membranes. The adsorption behavior of Cu2+ on the hybrid membranes was studied, and a promoted adsorption and elution efficiency of PVDF/TiO2 hybrid membranes were observed compared with that of the pristine PVDF film. Meanwhile, the surface contact angle, pure water flux and static adsorption of bovine serum albumin (BSA) on the hybrid membranes were also measured to study the effects of TiO2 nanoparticles. It was found that the TiO2 nanoparticles improved the surface hydrophilicity and permeability of PVDF membranes, and the decreasing adsorption capacity of BSA indicated the promoted antifouling ability of PVDF membranes. Such the PVDF/TiO2 hybrid membranes exhibit potential applications in the separation and pre-concentration of metal ions.

  3. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode.

    PubMed

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  4. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode.

    PubMed

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light.

  5. ZnFe2O4-TiO2 Nanoparticles within Mesoporous MCM-41

    PubMed Central

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe2O4-TiO2/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe2O4-TiO2 nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe2O4 nanoparticles can inhibit the transformation of anatase into rutile phase of TiO2. Incorporation of ZnFe2O4-TiO2 within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO2 to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO2, indicating an interesting application in the photodegradation and photoelectric fields. PMID:22919325

  6. Design of Novel Visible Light Active Photocatalyst Materials: Surface Modified TiO2.

    PubMed

    Nolan, Michael; Iwaszuk, Anna; Lucid, Aoife K; Carey, John J; Fronzi, Marco

    2016-07-01

    Work on the design of new TiO2 based photocatalysts is described. The key concept is the formation of composite structures through the modification of anatase and rutile TiO2 with molecular-sized nanoclusters of metal oxides. Density functional theory (DFT) level simulations are compared with experimental work synthesizing and characterizing surface modified TiO2 . DFT calculations are used to show that nanoclusters of metal oxides such as TiO2 , SnO/SnO2 , PbO/PbO2 , ZnO and CuO are stable when adsorbed at rutile and anatase surfaces, and can lead to a significant red shift in the absorption edge which will induce visible light absorption; this is the first requirement for a useful photocatalyst. The origin of the red shift and the fate of excited electrons and holes are determined. For p-block metal oxides the oxidation state of Sn and Pb can be used to modify the magnitude of the red shift and its mechanism. Comparisons of recent experimental studies of surface modified TiO2 that validate our DFT simulations are described. These nanocluster-modified TiO2 structures form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with a correct choice of nanocluster modified can be applied to other reactions. PMID:26833714

  7. ZnFe2O4-TiO2 nanoparticles within mesoporous MCM-41.

    PubMed

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe(2)O(4)-TiO(2)/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N(2) adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe(2)O(4)-TiO(2) nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe(2)O(4) nanoparticles can inhibit the transformation of anatase into rutile phase of TiO(2). Incorporation of ZnFe(2)O(4)-TiO(2) within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO(2) to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO(2), indicating an interesting application in the photodegradation and photoelectric fields.

  8. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode

    PubMed Central

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  9. Controlled synthesis of highly dispersed TiO2 nanoparticles using SBA-15 as hard template.

    PubMed

    Zhao, Li; Yu, Jiaguo

    2006-12-01

    Highly dispersed TiO2 nanoparticles were successfully synthesized by a wet impregnation method using SBA-15 as hard template for confining the growth of TiO2 nanocrystals, and then calcined at 550 degrees C in muffle furnace for 2 h. The as-synthesized samples were characterized with Fourier transform infrared spectra (FTIR), Raman spectroscopy, diffuse reflectance UV-visible spectroscopy (UV-vis), powder X-ray diffraction (XRD), small-angle X-ray diffraction (SAXRD), nitrogen adsorption, transmission electron microscopy (TEM) and photoluminescence spectra (PL). It was found that SBA-15 contained abundant silanol groups after removal of triblock copolymers by ethanol extraction and could easily adsorb a great number of titanium alkoxide via chemisorption. After subsequent hydrolysis of the anchored Ti complexes and calcination of the amorphous TiO2, anatase TiO2 nanocrystals with spherical shape and uniform particle diameter of about 6 nm were formed. A blue shift was observed in UV-vis absorption spectra due to the quantum size effect of TiO2 nanoparticles. Moreover, the as-prepared TiO2 nanoparticles showed a high PL intensity due to an increase in the recombination rate of photogenerated electrons and holes under UV light irradiation. PMID:16989852

  10. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    NASA Astrophysics Data System (ADS)

    Guo, Wenlu; Liu, Xiaolin; Huo, Pengwei; Gao, Xun; Wu, Di; Lu, Ziyang; Yan, Yongsheng

    2012-07-01

    Anatase TiO2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg-1 of the salicylic acid onto TiO2 (temperature: 150, time: 48 h).

  11. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    NASA Astrophysics Data System (ADS)

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-05-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion.

  12. Preparation and characterization of TiO 2-cationic hybrid nanoparticles as electrophoretic particles

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Deng, Liandong; Xing, Jinfeng; Dong, Anjie; Li, Xianggao

    2012-01-01

    The hybrid nanoparticles (TiO2-HNPs) with TiO2 nanoparticles as core and with poly(N,N-dimethylaminoethyl methacrylate-co-methyl methacrylate) by using triallylamine as cross-linking agent as shell were firstly prepared via atom transfer radical polymerization (ATRP) in methanol. Then the hybrid nanoparticles with positive charge were produced by the quaternization with methyl iodide as quaternization reagent so as to endow them with greater electrophoretic mobility. The cationic hybrid nanoparticles (TiO2-CHNPs) were studied by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) measurements. The results indicate that the cationic polymer is successfully grafted on the surface of the TiO2 nanoparticles. The particle size of TiO2-CHNPs is about 150 nm and the polydispersity index (PDI) is 0.307. The zeta potential, the contrast ratio of white state to dark state and response time of TiO2-CHNPs are +16.8 mV, 30 and 3 s, respectively, which show the potential application prospect in the development of electrophoretic ink.

  13. Composite WO3/TiO2 nanostructures for high electrochromic activity

    DOE PAGES

    Reyes-Gil, Karla R.; Stephens, Zachary D.; Stavila, Vitalie; Robinson, David B.

    2015-01-06

    A composite material consisting of TiO2 nanotubes (NT) with WO3 electrodeposited on its surface has been fabricated, detached from its Ti substrate, and attached to a fluorine-doped tin oxide (FTO) film on glass for application to electrochromic (EC) reactions. Several adhesion layers were tested, finding that a paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length and WO3 concentration on the EC performancemore » were studied. As a result, the composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast, and longer memory time compared with the pure WO3 and TiO2 materials« less

  14. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    SciTech Connect

    Reyes, Karla Rosa; Stephens, Zachary Dan.; Robinson, David B.

    2013-05-01

    A composite material consisting of TiO2 nanotubes (NTs) with WO3 electrodeposited homogeneously on its surface has been fabricated, detached from its substrate, and attached to a fluorine-doped tin oxide film on glass for application to electrochromic (EC) reactions. A paste of TiO2 made from commercially available TiO2 nanoparticles creates an interface for the TiO2 NT film to attach to the FTO glass, which is conductive and does not cause solution-phase ions in an electrolyte to bind irreversibly with the material. The effect of NT length on the current density and the EC contrast of the material were studied. The EC redox reaction seen in this material is diffusion- limited, having relatively fast reaction rates at the electrode surface. The composite WO3/TiO2 nanostructures showed higher ion storage capacity, better stability, enhanced EC contrast and longer memory time compared with the pure WO3 and TiO2.

  15. 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. PMID:24821008

  16. Effective photocatalysis of functional nanocomposites based on carbon and TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lin, Chan; Song, Yang; Cao, Lixin; Chen, Shaowei

    2013-05-01

    A unique nanocomposite C-TiO2 was prepared by the growth of TiO2 on carbon nanoparticles using a simple hydrothermal procedure. Transmission electron microscopic (TEM) measurements showed that the nanocomposites exhibited an average core diameter of approximately 5 nm with a rather well-defined lattice space (0.4 nm) that was somewhat larger than that (0.38 nm) of the (100) crystalline planes of anatase TiO2. This lattice expansion was accounted for by the formation of surface defect dipoles of the nanosized TiO2 particles. X-ray photoelectron spectroscopic (XPS) measurements suggested that partial charge transfer occurred from carbon nanoparticles to TiO2 by the interfacial Ti-O-C linkages, which led to effective diminishment of the C-TiO2 photoluminescence as compared to that of pure TiO2 or carbon nanoparticles, suggesting intimate electronic interactions between the carbon and TiO2 components in the nanocomposites. Such unique characteristics were then exploited for the effective photocatalytic degradation of organic pollutants, as exemplified by methylene blue, by C-TiO2 under UV photoirradiation. Experimental measurements showed that the photocatalytic activity of C-TiO2 nanocomposites was about twice that of TiO2 alone, whereas little activity was observed with carbon nanoparticles. This was attributed to the electron-accepting sites on the carbon nanoparticles that facilitated interfacial charge separation.A unique nanocomposite C-TiO2 was prepared by the growth of TiO2 on carbon nanoparticles using a simple hydrothermal procedure. Transmission electron microscopic (TEM) measurements showed that the nanocomposites exhibited an average core diameter of approximately 5 nm with a rather well-defined lattice space (0.4 nm) that was somewhat larger than that (0.38 nm) of the (100) crystalline planes of anatase TiO2. This lattice expansion was accounted for by the formation of surface defect dipoles of the nanosized TiO2 particles. X-ray photoelectron spectroscopic (XPS) measurements suggested that partial charge transfer occurred from carbon nanoparticles to TiO2 by the interfacial Ti-O-C linkages, which led to effective diminishment of the C-TiO2 photoluminescence as compared to that of pure TiO2 or carbon nanoparticles, suggesting intimate electronic interactions between the carbon and TiO2 components in the nanocomposites. Such unique characteristics were then exploited for the effective photocatalytic degradation of organic pollutants, as exemplified by methylene blue, by C-TiO2 under UV photoirradiation. Experimental measurements showed that the photocatalytic activity of C-TiO2 nanocomposites was about twice that of TiO2 alone, whereas little activity was observed with carbon nanoparticles. This was attributed to the electron-accepting sites on the carbon nanoparticles that facilitated interfacial charge separation. Electronic supplementary information (ESI) available: XRD patterns of TiO2 and C-TiO2 nanoparticles. See DOI: 10.1039/c3nr01033c

  17. Photocatalytic properties of TiO2 and TiO2/Pt: a sol-precipitation, sonochemical and hydrothermal approach.

    PubMed

    Žunič, Vojka; Vukomanović, Marija; Škapin, Srečo D; Suvorov, Danilo; Kovač, Janez

    2014-01-01

    In this work we prepared TiO2 nano-powders and TiO2/Pt nano-composites via three synthesis methods (sol-precipitation, sonochemical method, hydrothermal method) starting with the same precursors and media. To evaluate and compare the physical properties of the prepared materials, X-ray diffraction analysis, BET measurements, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron microscopy (TEM, HRTEM, SAED) were applied. The results showed changes to the TiO2 phase composition and crystallinity, the specific surface area as well as the platinum's particle shape and size, depending on the method of synthesis. To determine the photocatalytic efficiency of the prepared materials, the photocatalytic discoloration of the methylene blue solution was evaluated using UV-Vis spectroscopy. The important properties required for a high photocatalytic activity, related to the surface characteristics and the phase composition, were determined in terms of the synthesis method. It was concluded that the optimum characteristics were obtained when using the hydrothermal approach, where the TiO2 had two phases, i.e., - anatase and rutile, a Pt-phase in the form of nanoparticles and adsorbed Pt-molecular species, as well as the presence of available free surface hydroxyl groups. Such characteristics had a critical influence on the photocatalytic activity of the final material.

  18. Impact of growth kinetics on morphology and pore structure of TiO2-one-pot synthesis of macroporous TiO2 microspheres.

    PubMed

    Zhong, Ziyi; Chen, Fengxi; Ang, Thiam-Peng; Han, Yifan; Lim, Weiqiang; Gedanken, Aharon

    2006-06-12

    Titanium dioxide was synthesized by the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of acetic acid, 2-propanol, and organic amines (octylamine, aniline, and isobutylamine). H2O was supplied by an esterification reaction between acetic acid and 2-propanol (denoted as H2Oe), and/or by intentionally adding it (denoted as H2Oa). It was found that the quantity of H2Oa plays a crucial role in the morphology and porous structure of the final TiO2 product. Without the addition of H2Oa, 1D and porous TiO2 was synthesized. With the addition of H2Oa, and when the H2Oa:TiO2 molar ratio was in the range of 1:1 to 60:1, macroporous TiO2 microspheres possessing a large surface area and high thermal stability were obtained. When the H2Oa:TiO2 molar ratio exceeded 60:1, porous TiO2 with an irregular shape was formed. The variation in the morphology and porous structure is attributed to the manipulation of the growth kinetics by the addition of water. PMID:16749824

  19. Two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched and P25-coated TiO2 nanotube arrays and their photocurrent performances

    PubMed Central

    2011-01-01

    We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis. PMID:21711607

  20. Effect of the Method of Synthesis in the Photoactivity of TiO2-Co and TiO2-CoCe Materials.

    PubMed

    Mantilla, Angeles; Valverde-Aguilar, Guadalupe; Suarez, Víctor; Navarro-Cerón, Elizabeth; Rodríguez, Rodrigo; Tzompantzi, Francisco; Morales-Mendoza, Getsemaní

    2015-09-01

    Cobalt modified TiO2 and cobalt-cerium modified TiO2 were synthesized by sol gel technique using two different routes. In the first case the material was prepared by adding directly the precursor of metal (Co) during the sol-gel synthesis (In situ). The second one consisted in the impregnation of the supports of TiO2 and Ce-TiO2 prepared by sol-gel with a cobalt solution (Impregnated). The materials obtained were characterized by XRD and their textural properties were determined. The effect of the technique of synthesis as well as the presence of cerium in the photocatalytic properties of the material was evaluated in the photodegradation of phenol in aqueous phase. According to the results obtained in this study, it can be concluded that both, the integration of the metals during the sol-gel synthesis and the presence of cerium significantly improves the photocatalytic activity of TiO2.

  1. Plasmon-induced spatial electron transfer between single Au nanorods and ALD-coated TiO2: dependence on TiO2 thickness.

    PubMed

    Zheng, Zhaoke; Tachikawa, Takashi; Majima, Tetsuro

    2015-10-01

    We employed single-particle photoluminescence (PL) measurements to investigate the interfacial electron transfer between single Au nanorods (NRs) and TiO2 coated by ALD. Analyzing the energy relaxation path of plasmon-generated hot electrons as well as the PL intensities allowed for the detection and study of the interfacial electron transfer process spatially.

  2. Synchrotron verification of TiO2 accumulation in cucumber fruit: a possible pathway of TiO2 nanoparticle transfer from soil into the food chain.

    PubMed

    Servin, Alia D; Morales, Maria Isabel; Castillo-Michel, Hiram; Hernandez-Viezcas, Jose Angel; Munoz, Berenice; Zhao, Lijuan; Nunez, Jose E; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L

    2013-10-15

    The transfer of nanoparticles (NPs) into the food chain through edible plants is of great concern. Cucumis sativus L. is a freshly consumed garden vegetable that could be in contact with NPs through biosolids and direct agrichemical application. In this research, cucumber plants were cultivated for 150 days in sandy loam soil treated with 0 to 750 mg TiO2 NPs kg(-1). Fruits were analyzed using synchrotron μ-XRF and μ-XANES, ICP-OES, and biochemical assays. Results showed that catalase in leaves increased (U mg(-1) protein) from 58.8 in control to 78.8 in 750 mg kg(-1) treatment; while ascorbate peroxidase decreased from 21.9 to 14.1 in 500 mg kg(-1) treatment. Moreover, total chlorophyll content in leaves increased in the 750 mg kg(-1) treatment. Compared to control, FTIR spectra of fruit from TiO2 NP treated plants showed significant differences (p ≤ 0.05) in band areas of amide, lignin, and carbohydrates, suggesting macromolecule modification of cucumber fruit. In addition, compared with control, plants treated with 500 mg kg(-1) had 35% more potassium and 34% more phosphorus. For the first time, μ-XRF and μ-XANES showed root-to-fruit translocation of TiO2 in cucumber without biotransformation. This suggests TiO2 could be introduced into the food chain with unknown consequences.

  3. On the preparation of TiO2-sepiolite hybrid materials for the photocatalytic degradation of TCE: influence of TiO2 distribution in the mineralization.

    PubMed

    Suárez, Silvia; Coronado, Juan M; Portela, Raquel; Martín, Juan Carlos; Yates, Malcolm; Avila, Pedro; Sánchez, Benigno

    2008-08-15

    Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO2 film (coated materials). The influence of the OH- surface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OH- groups of the adsorbent and favoring the TCE mimeralization.

  4. Nanoparticulate anatase TiO2 (TiO2 NPs) upregulates the expression of silkworm (Bombyx mori) neuropeptide receptor and promotes silkworm feeding, growth, and silking.

    PubMed

    Ni, Min; Zhang, Hua; Li, Fan Chi; Wang, Bin Bin; Xu, Kai Zun; Shen, Wei De; Li, Bing

    2015-06-01

    Bombyx mori orphan G protein-coupled receptor, BNGR-A4, is the specific receptor of B. mori neuropeptide F (BmNPFR, neuropeptide F designated NPF). BmNPFR binds specifically and efficiently to B. mori neuropeptides BmNPF1a and BmNPF1b, which activates the ERK1/2 signaling pathway to regulate B. mori food intake and growth. Titanium dioxide nanoparticles (TiO2 NPs) can promote B. mori growth. However, whether the mechanisms of TiO2 NPs' effects are correlated with BmNPFR remains unknown. In this study, the effects of TiO2 NPs (5mg/L) feeding and BmNPFR-dsRNA injection on B. mori food intake and growth were investigated; after TiO2 NPs treatments, B. mori food intake, body weight, and cocoon shell weight were 5.82%, 4.64%, and 9.30% higher, respectively, than those of controls. The food intake, body weight, and cocoon shell weight of the BmNPFR-dsRNA injection group were reduced by 8.05%, 6.28%, and 6.98%, respectively, compared to the control. After TiO2 NPs treatment for 72h, the transcriptional levels of BmNPFR, BmNPF1a, and BmNPF1b in the midgut were 1.58, 1.43, and 1.34-folds, respectively, of those of the control, but 1.99, 2.26, and 2.19-folds, respectively, of the BmNPFR-dsRNA injection group; the phosphorylation level of MAPK was 24.03% higher than the control, while the phosphorylation level of BmNPFR-dsRNA injection group was 71.00% of control. The results indicated that TiO2 NPs affect B. mori feeding and growth through increasing the expression of BmNPFR. This study helps clarify the roles of BmNPF/BmNPFR system in TiO2 NPs' effects on B. mori feeding, growth, and development.

  5. Nanoparticle size and combined toxicity of TiO2 and DSLS (surfactant) contribute to lysosomal responses in digestive cells of mussels exposed to TiO2 nanoparticles.

    PubMed

    Jimeno-Romero, A; Oron, M; Cajaraville, M P; Soto, M; Marigómez, I

    2016-10-01

    The aim of this investigation was to understand the bioaccumulation, cell and tissue distribution and biological effects of disodium laureth sulfosuccinate (DSLS)-stabilised TiO2 nanoparticles (NPs) in marine mussels, Mytilus galloprovincialis. Mussels were exposed in vivo to 0.1, 1 and 10 mg Ti/L either as TiO2 NPs (60 and 180 nm) or bulk TiO2, as well as to DSLS alone. A significant Ti accumulation was observed in mussels exposed to TiO2 NPs, which were localised in endosomes, lysosomes and residual bodies of digestive cells, and in the lumen of digestive tubules, as demonstrated by ultrastructural observations and electron probe X-ray microanalysis. TiO2 NPs of 60 nm were internalised within digestive cell lysosomes to a higher extent than TiO2 NPs of 180 nm, as confirmed by the quantification of black silver deposits after autometallography. The latter were localised mainly forming large aggregates in the lumen of the gut. Consequently, lysosomal membrane stability (LMS) was significantly reduced upon exposure to both TiO2 NPs although more markedly after exposure to TiO2-60 NPs. Exposure to bulk TiO2 and to DSLS also affected the stability of the lysosomal membrane. Thus, effects on the lysosomal membrane depended on the nanoparticle size and on the combined biological effects of TiO2 and DSLS.

  6. Structure -- Magnetic Property Correlations in TiO 2 Nanotube Arrays

    NASA Astrophysics Data System (ADS)

    Mohammad Hosseinpour, Pegah

    TiO2 nanotube arrays are promising candidates for applications such as photocatalysis and for potential employment in spin-electronic (spintronic) devices. The functionality of TiO2-based nanotubes is highly dependent on their structure (microstructure and crystallographic symmetry) and magnetic properties. Unified understanding of the influence of these factors on the electronic structure of TiO2 is of paramount importance towards engineering these materials. This Dissertation aims at investigating the correlations of the morphology, crystallinity, crystal structure, electronic structure and magnetic properties of TiO2 nanotubes, with potential relevance to their functionality. Self-ordered arrays of amorphous TiO2 nanotubes (pure and Fe-doped with cationic concentration of ~2.1 at%) were synthesized by the electrochemical anodization technique, followed by subjecting them to thermal treatments up to 450 °C to crystallize these nanostructures. A variety of probes---morphological, structural, magnetic and spectroscopic---were used to characterize the properties of these nanostructures as functions of their processing conditions and the dopant content. Structure-functionality relationships in these nanostructures were verified by examining the photodegradation rate of methyl orange (a model water pollutant) in presence of TiO2 nanotubes under UV-Visible light irradiation. Results from this Dissertation research demonstrated that post-synthesis processing conditions---specifically, the nature of the annealing environment, as well as the presence of an external dopant, can alter the crystal structure and local electronic environment in TiO2 nanotubes, with subsequent effects on the magnetic properties of these nanostructures. The fundamental knowledge obtained in this research, on the interrelations of structural-magnetic properties and their potential influence on the functionality of TiO 2-based nanotubes, can be extended to the metal oxide semiconducting systems in general and is anticipated to provide avenues toward novel materials with enhanced functionality that originates from such tailored structural and magnetic characteristics. Despite the success achieved in this Dissertation, there are still open questions to be addressed in order to further enhance the fundamental knowledge of structure---magnetic property correlations in TiO2 nanotubes. In this regard, the concluding section of this Dissertation provides recommendations for additional experiments. Accomplishment of these recommendations is anticipated to provide enhanced insight into the various aspects of property-functionality relationships in TiO2-based nanomaterials, and provides paths to engineer novel multifunctional oxide-based materials for energy-related applications.

  7. High Mobility of Graphene-Based Flexible Transparent Field Effect Transistors Doped with TiO2 and Nitrogen-Doped TiO2.

    PubMed

    Wu, Yu-Hsien; Tseng, Po-Yuan; Hsieh, Ping-Yen; Chou, Hung-Tao; Tai, Nyan-Hwa

    2015-05-13

    Graphene with carbon atoms bonded in a honeycomb lattice can be tailored by doping various species to alter the electrical properties of the graphene for fabricating p-type or n-type field-effect transistors (FETs). In this study, large-area and single-layer graphene was grown on electropolished Cu foil using the thermal chemical vapor deposition method; the graphene was then transferred onto a poly(ethylene terephthalate) (PET) substrate to produce flexible, transparent FETs. TiO2 and nitrogen-doped TiO2 (N-TiO2) nanoparticles were doped on the graphene to alter its electrical properties, thereby enhancing the carrier mobility and enabling the transistors to sense UV and visible light optically. The results indicated that the electron mobility of the graphene was 1900 cm(2)/(V·s). Dopings of TiO2 and N-doped TiO2 (1.4 at. % N) lead to n-type doping effects demonstrating extremely high carrier mobilities of 53000 and 31000 cm(2)/(V·s), respectively. Through UV and visible light irradiation, TiO2 and N-TiO2 generated electrons and holes; the generated electrons transferred to graphene channels, causing the FETs to exhibit n-type electric behavior. In addition, the Dirac points of the graphene recovered to their original state within 5 min, confirming that the graphene-based FETs were photosensitive to UV and visible light. In a bending state with a radius of curvature greater than 2.0 cm, the carrier mobilities of the FETs did not substantially change, demonstrating the application possibility of the fabricated graphene-based FETs in photosensors.

  8. Novel hollow mesoporous 1D TiO2 nanofibers as photovoltaic and photocatalytic materials

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Thavasi, Velmurugan; Mhaisalkar, S. G.; Ramakrishna, Seeram

    2012-02-01

    Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (η = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts.Hollow mesoporous one dimensional (1D) TiO2 nanofibers are successfully prepared by co-axial electrospinning of a titanium tetraisopropoxide (TTIP) solution with two immiscible polymers; polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell spinneret, followed by annealing at 450 °C. The annealed mesoporous TiO2 nanofibers are found to having a hollow structure with an average diameter of 130 nm. Measurements using the Brunauer-Emmett-Teller (BET) method reveal that hollow mesoporous TiO2 nanofibers possess a high surface area of 118 m2 g-1 with two types of mesopores; 3.2 nm and 5.4 nm that resulted from gaseous removal of PEO and PVP respectively during annealing. With hollow mesoporous TiO2 nanofibers as the photoelectrode in dye sensitized solar cells (DSSC), the solar-to-current conversion efficiency (η) and short circuit current (Jsc) are measured as 5.6% and 10.38 mA cm-2 respectively, which are higher than those of DSSC made using regular TiO2 nanofibers under identical conditions (η = 4.2%, Jsc = 8.99 mA cm-2). The improvement in the conversion efficiency is mainly attributed to the higher surface area and mesoporous TiO2 nanostructure. It facilitates the adsorption of more dye molecules and also promotes the incident photon to electron conversion. Hollow mesoporous TiO2 nanofibers with close packing of grains and crystals intergrown with each other demonstrate faster electron diffusion, and longer electron recombination time than regular TiO2 nanofibers as well as P25 nanoparticles. The surface effect of hollow mesoporous TiO2 nanofibers as a photocatalyst for the degradation of rhodamine dye was also investigated. The kinetic study shows that the hollow mesoporous surface of the TiO2 nanofibers influenced its interactions with the dye, and resulted in an increased catalytic activity over P25 TiO2 nanocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11251e

  9. Novel phosphorus doped carbon nitride modified TiO2 nanotube arrays with improved photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Su, Jingyang; Geng, Ping; Li, Xinyong; Zhao, Qidong; Quan, Xie; Chen, Guohua

    2015-10-01

    Novel phosphorus-doped graphitic-carbon nitride (P-C3N4) modified vertically aligned TiO2 nanotube arrays (NTs) were designed and synthesized. They can significantly enhance the conduction and utilization of photogenerated charge carriers of TiO2 NTs. The heterostructure was successfully fabricated through a three-step process: electrochemical anodization and wet-dipping followed by thermal polymerization. The prepared P-C3N4/TiO2 NTs exhibit enhanced light-absorption characteristics and improved charge separation and transfer ability, thus resulting in a 3-fold photocurrent (1.98 mA cm-2 at 0 V vs. Ag/AgCl) compared with that of pure TiO2 NTs (0.66 mA cm-2 at 0 V vs. Ag/AgCl) in 1 M NaOH solution. The prepared P-C3N4/TiO2 NT photoelectrodes also present excellent photocatalytic and photoelectrocatalytic capabilities in the degradation of methylene blue (MB). The kinetic rate of P-C3N4/TiO2 NTs in the photoelectrocatalytic process for MB is 2.7 times that of pristine TiO2 NTs. Furthermore, the prepared sample was used as a photoanode for solar-driven water splitting, giving a H2 evolution rate of 36.6 μmol h-1 cm-2 at 1.0 V vs. RHE under simulated solar light illumination. This novel structure with a rational design for a visible light response shows potential for metal free materials in photoelectrochemical applications.Novel phosphorus-doped graphitic-carbon nitride (P-C3N4) modified vertically aligned TiO2 nanotube arrays (NTs) were designed and synthesized. They can significantly enhance the conduction and utilization of photogenerated charge carriers of TiO2 NTs. The heterostructure was successfully fabricated through a three-step process: electrochemical anodization and wet-dipping followed by thermal polymerization. The prepared P-C3N4/TiO2 NTs exhibit enhanced light-absorption characteristics and improved charge separation and transfer ability, thus resulting in a 3-fold photocurrent (1.98 mA cm-2 at 0 V vs. Ag/AgCl) compared with that of pure TiO2 NTs (0.66 mA cm-2 at 0 V vs. Ag/AgCl) in 1 M NaOH solution. The prepared P-C3N4/TiO2 NT photoelectrodes also present excellent photocatalytic and photoelectrocatalytic capabilities in the degradation of methylene blue (MB). The kinetic rate of P-C3N4/TiO2 NTs in the photoelectrocatalytic process for MB is 2.7 times that of pristine TiO2 NTs. Furthermore, the prepared sample was used as a photoanode for solar-driven water splitting, giving a H2 evolution rate of 36.6 μmol h-1 cm-2 at 1.0 V vs. RHE under simulated solar light illumination. This novel structure with a rational design for a visible light response shows potential for metal free materials in photoelectrochemical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04562b

  10. Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time.

    PubMed

    Lv, Jinze; Zhu, Lizhong

    2013-01-01

    A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m(-3) cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4-7.9 times higher than that on P25. Removal efficiency via photocatalysis followed'the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180 > P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

  11. The interactions between TiO2 and graphene with surface inhomogeneity determined using density functional theory.

    PubMed

    Bukowski, Brandon; Deskins, N Aaron

    2015-11-28

    TiO2/graphene composites have shown promise as photocatalysts, leading to improved electronic properties. We have modeled using density functional theory TiO2/graphene interfaces formed between graphene with various defects/functional groups (C vacancy, epoxide, and hydroxyl) and TiO2 clusters of various sizes. We considered clusters from 3 to 45 atoms, the latter a nanoparticle of ∼1 nm in size. Our results show that binding to pristine graphene is dominated by van der Waals forces, and that C vacancies or epoxide groups lead to much stronger binding between the graphene and TiO2. Such sites may serve to anchor TiO2 to graphene. Graphene surfaces with hydroxyls however lead to OH transfer to TiO2 and weak interactions between the graphene and the hydroxylated TiO2 cluster. Charge transfer may occur between TiO2 and graphene in various directions (graphene to TiO2 or TiO2 to graphene), depending on the state of the graphene surface, based on overlap of the density of states. Our work indicates that graphene surface defects or functional groups may have a significant effect on the stability, structure, and photoactivity of these materials.

  12. Synthesis and anti-staphylococcal activity of TiO2 nanoparticles and nanowires in ex vivo porcine skin model.

    PubMed

    Nataraj, Namrata; Anjusree, G S; Madhavan, Asha Anish; Priyanka, P; Sankar, Deepthi; Nisha, N; Lakshmi, S V; Jayakumar, R; Balakrishnan, Avinash; Biswas, Raja

    2014-05-01

    Staphylococcus aureus is one of the major causes of skin and soft tissue infections. In this study we compared the antimicrobial activity of two different TiO2 nanoformulations against Staphylococcus aureus. We synthesized TiO2 nanoparticles of approximately 80 nm diameter and TiO2 nanowires of approximately 100 nm diameter. Both nanoformulations possess anti-microbial activity; were non-hemolytic and cytocompatible. However, the anti-staphylococcal activity of TiO2 nanowires was better than the nanoparticles. In broth culture, growth of S. aureus was only partially inhibited by 2% and 4 wt% TiO2 nanoparticles and completely inhibited by TiO2 nanowires till 24 h. TiO2 nanowires treated S. aureus cells exhibits diminished membrane potential than nanoparticle treated cells. The anti-microbial properties of both TiO2 nanoformulations were validated using ex vivo porcine skin model which supplements the in vitro assays. Anti-bacterial activity of the TiO2 nanowires were also validated against multi drug resistant pathogenic strains of S. aureus, showing the clinical potency of the TiO2 nanowires compared to its nanoparticles.

  13. Influence of TiO2 Nanorod Arrays on the Bilayered Photoanode for Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Cao, Ya; Li, Zhen; Wang, Yang; Zhang, Tao; Li, Yinchang; Liu, Xueqin; Li, Fei

    2016-10-01

    A TiO2 bilayered structure consisting of TiO2 nanoparticles (TiO2NP) as an overlayer and single-crystal rutile TiO2 nanorods (TiO2 NRs) as an underlayer on a transparent conductive fluorine-doped tin oxide substrate was designed as the photoanode of dye-sensitized solar cells (DSSCs) through a facile hydrothermal treatment followed by a doctor-blade method. DSSCs based on the hierarchical TiO2 nano-architecture photoelectrode shows a power conversion efficiency of 7.39% because the relatively large specific surface area of TiO2NP increased the dye absorption, and oriented one-dimensional TiO2 NRs enhanced the light harvesting capability, accelerating interfacial electron transport. In particular, we observed the growth morphology of the TiO2 nanorod arrays in the bilayered photoanode and the influence of the whole solar cell. The result indicated that the TiO2 NRs layer clearly impacted the photoelectron chemical properties, while the vertical and intensive nanorod arrays significantly increased their performance.

  14. Improved efficiency of dye-sensitized solar cells applied with nanostructured N-F doped TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Yang, Shuming; Xue, Hongbin; Wang, Hongjun; Kou, Huizhi; Wang, Jichao; Zhu, Guanghui

    2012-07-01

    Dye-sensitized solar cells (DSSCs) were fabricated with N-F-doped TiO2 electrodes. The XRD pattern of the N-F-doped TiO2 is almost the same as that of pure TiO2, showing that N and F doping has little influence on the formation of anatase titania. The influence of dopant N and F on band energetics and photoelectrochemical properties of nanostructured TiO2 electrodes were investigated. Compared with pure TiO2 electrodes, the Efb of N-F-doped TiO2 electrodes shifted a little in electrolytes containing LiClO4. However the total trap densities were remarkably decreased as TiO2 electrodes were doped with N and F. Finally the N-F-doped TiO2 electrodes were sensitized with N3 and their photoelectrochemical properties were studied. Experimental results showed that the photoelectric conversion efficiency of N3 sensitized N-F-doped TiO2 electrodes was 8.61% under irradiation of 100 mW cm-2 white light, about 17.1% higher than that of a pure TiO2 electrode.

  15. The design, fabrication, and photocatalytic utility of nanostructured semiconductors: focus on TiO2-based nanostructures

    PubMed Central

    Banerjee, Arghya Narayan

    2011-01-01

    Recent advances in basic fabrication techniques of TiO2-based nanomaterials such as nanoparticles, nanowires, nanoplatelets, and both physical- and solution-based techniques have been adopted by various research groups around the world. Our research focus has been mainly on various deposition parameters used for fabricating nanostructured materials, including TiO2-organic/inorganic nanocomposite materials. Technically, TiO2 shows relatively high reactivity under ultraviolet light, the energy of which exceeds the band gap of TiO2. The development of photocatalysts exhibiting high reactivity under visible light allows the main part of the solar spectrum to be used. Visible light-activated TiO2 could be prepared by doping or sensitizing. As far as doping of TiO2 is concerned, in obtaining tailored material with improved properties, metal and nonmetal doping has been performed in the context of improved photoactivity. Nonmetal doping seems to be more promising than metal doping. TiO2 represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as an antibacterial agent because of its strong oxidation activity and superhydrophilicity. Therefore, applications of TiO2 in terms of photocatalytic activities are discussed here. The basic mechanisms of the photoactivities of TiO2 and nanostructures are considered alongside band structure engineering and surface modification in nanostructured TiO2 in the context of doping. The article reviews the basic structural, optical, and electrical properties of TiO2, followed by detailed fabrication techniques of 0-, 1-, and quasi-2-dimensional TiO2 nanomaterials. Applications and future directions of nanostructured TiO2 are considered in the context of various photoinduced phenomena such as hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis. PMID:24198485

  16. 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.

  17. Tailoring of antibacterial Ag nanostructures on TiO2 nanotube layers by magnetron sputtering.

    PubMed

    Uhm, Soo-Hyuk; Song, Doo-Hoon; Kwon, Jae-Sung; Lee, Sang-Bae; Han, Jeon-Geon; Kim, Kyoung-Nam

    2014-04-01

    To reduce the incidence of postsurgical bacterial infection that may cause implantation failure at the implant-bone interface, surface treatment of titanium implants with antibiotic materials such as silver (Ag) has been proposed. The purpose of this work was to create TiO2 nanotubes using plasma electrolytic oxidation (PEO), followed by formation of an antibacterial Ag nanostructure coating on the TiO2 nanotube layer using a magnetron sputtering system. PEO was performed on commercially pure Ti sheets. The Ag nanostructure was added onto the resulting TiO2 nanotube using magnetron sputtering at varying deposition rates. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the surface, and Ag content on the TiO2 nanotube layer was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Scanning probe microscopy for surface roughness and contact angle measurement were used to indirectly confirm enhanced TiO2 nanotube hydrophilicity. Antibacterial activity of Ag ions in solution was determined by inductively coupled plasma mass spectrometry and antibacterial testing against Staphylococcus aureus (S. aureus). In vitro, TiO2 nanotubes coated with sputtered Ag resulted in significantly reduced S. aureus. Cell viability assays showed no toxicity for the lowest sputtering time group in the osteoblastic cell line MC3T3-E1. These results suggest that a multinanostructured layer with a biocompatible TiO2 nanotube and antimicrobial Ag coating is a promising biomaterial that can be tailored with magnetron sputtering for optimal performance.

  18. Cotransport of TiO2 nanoparticles and Pseudomonas putida in porous media

    NASA Astrophysics Data System (ADS)

    Zaharis, Ioannis; Manariotis, Ioannis D.; Chrysikopoulos, Constantinos V.

    2015-04-01

    The scope of this study was to investigate the cotransport of Pseudomonas putida and TiO2 nanoparticles (NPs) in porous media. Flowthrough experiments were conducted in glass columns with diameter of 2.5 cm and length of 30 cm, packed with 2-mm diameter spherical glass beads. Anatase TiO2 NPs solutions were prepared in distilled water of at two different concentrations: 5 and 50 mg/L. The concentration of P. putida solutions varied from 105 to 109 cfu/mL. Initially, transport experiments were conducted separately for P. putida and TiO2 NPs. Subsequently, TiO2 and P. putida cotransport experiments were conducted. The concentration of TiO2 NPs was measured by a fluorescence spectrophotometer and P. putida concentration was determined by plate counts on agar plates and optical density measurements. All experiments were conducted with two different flow rates: 1 and 2 mL/min. The transport experiments with P. putida exhibited similar transport behavior with the tracer (NaBr) indicating that there was not considerable retention. The mass recovery of P. putida was close to 100% in all of the transport experiments conducted. However, the transport experiments with TiO2 NPs suggested that a significant portion of the NPs was retained in the column. Based on the cotransport experimental data, it is evident that the transport of P. putida was not significantly affected by the presence of TiO2. It should be noted that the mass recovery of NPs in the transport and costransport experiments was between 40 and 60%.

  19. Photocatalytic oxidation of organic dyes with visible-light-driven codoped TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Zhang, Dongfang; Zeng, Fanbin

    2011-06-01

    A novel copper (II) and zinc (II) codoped TiO2 photocatalyst was synthesized by a modified sol-gel method using titanium (IV) isopropoxide, Zn(NO3)2 · 6H2O and copper(Il) nitrate as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and photo-luminescence spectra (PL). The XRD results showed undoped and Zn, Cu-codoped TiO2 nanoparticles mainly including anatase phase and a tiny amount of Zn- and Cu-oxides exist in the mixed system, which is attributed to the decomposition of copper and zinc nitrates in the TiO2 gel to form CuO and ZnO and randomly dispersed on the TiO2 surface. On the basis of the optical characterization results, we found that the codoping of copper (II) and zinc (II) resulted a red shift of adsorption and lower recombination probability between electrons and holes, which were the reasons for high photocatalytic activity of Zn, Cu-codoped TiO2 nanoparticles under visible light (λ > 400 nm). The photocatalytic activity of samples was tested for degradation of methyl orange (MO) in solutions. The results indicated that the visible-light driven capability of the codoped catalyst were much higher than that of the pure TiO2 catalyst under visible irradiation. Because of the synergetic effect of copper (II) and zinc (II) element, the Zn, Cu-codoped TiO2 catalyst will show higher quantum yield and enhance absorption of visible light. In the end, a key mechanism was proposed in order to account for the enhanced activity.

  20. Visible light Cr(VI) reduction and organic chemical oxidation by TiO2 photocatalysis.

    PubMed

    Sun, Bo; Reddy, Ettireddy P; Smirniotis, Panagiotis G

    2005-08-15

    Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength > 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light.

  1. Gold nanoparticles-immobilized, hierarchically ordered, porous TiO2 nanotubes for biosensing of glutathione.

    PubMed

    Mers, Sv Sheen; Kumar, Elumalai Thambuswamy Deva; Ganesh, V

    2015-01-01

    Glutathione (GSH) is vital for several functions of our human body such as neutralization of free radicals and reactive oxygen compounds, maintaining the active forms of vitamin C and E, regulation of nitric oxide cycle, iron metabolism, etc. It is also an endogenous antioxidant in most of the biological reactions. Given the importance of GSH, a simple strategy is proposed in this work to develop a biosensor for quantitative detection of GSH. This particular biosensor comprises of gold nanoparticles (Au NPs)-immobilized, hierarchically ordered titanium dioxide (TiO2) porous nanotubes. Hexagonally arranged, honeycomb-like nanoporous tubular TiO2 electrodes are prepared by using a simple electrochemical anodization process by applying a constant potential of 30 V for 24 hours using ethylene glycol consisting of ammonium fluoride as an electrolytic medium. Structural morphology and crystalline nature of such TiO2 nanotubes are analyzed using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Interestingly, nanocomposites of TiO2 with Au NPs is prepared in an effort to alter the intrinsic properties of TiO2, especially tuning of its band gap. Au NPs are prepared by a well-known Brust and Schiffrin method and are immobilized onto TiO2 electrodes which act as a perfect electrochemical sensing platform for GSH detection. Structural characterization and analysis of these modified electrodes are performed using FESEM, XRD, and UV-visible spectroscopic studies. GSH binding events on Au NPs-immobilized porous TiO2 electrodes are monitored by electrochemical techniques, namely, cyclic voltammetry (CV) and chronoamperometry (CA). Several parameters such as sensitivity, selectivity, stability, limit of detection, etc are investigated. In addition, Au NPs dispersed in aqueous medium are also explored for naked-eye detection of GSH using UV-visible spectroscopy in order to compare the performance of the proposed sensor. Our studies clearly indicate that these materials could potentially be used for GSH sensing applications.

  2. Superhydrophilic TiO2 thin film by nanometer scale surface roughness and dangling bonds

    NASA Astrophysics Data System (ADS)

    Bharti, Bandna; Kumar, Santosh; Kumar, Rajesh

    2016-02-01

    A remarkable enhancement in the hydrophilic nature of titanium dioxide (TiO2) films is obtained by surface modification in DC-glow discharge plasma. Thin transparent TiO2 films were coated on glass substrate by sol-gel dip coating method, and exposed in DC-glow discharge plasma. The plasma exposed TiO2 film exhibited a significant change in its wetting property contact angle, which is a representative of wetting property, has reduced to considerable limits 3.02° and 1.85° from its initial value 54.40° and 48.82° for deionized water and ethylene glycol, respectively. It is elucidated that the hydrophilic property of plasma exposed TiO2 films dependent mainly upon nanometer scale surface roughness. Variation, from 4.6 nm to 19.8 nm, in the film surface roughness with exposure time was observed by atomic force microscopy (AFM). Analysis of variation in the values of contact angle and surface roughness with increasing plasma exposure time reveal that the surface roughness is the main factor which makes the modified TiO2 film superhydrophilic. However, a contribution of change in the surface states, to the hydrophilic property, is also observed for small values of the plasma exposure time. Based upon nanometer scale surface roughness and dangling bonds, a variation in the surface energy of TiO2 film from 49.38 to 88.92 mJ/m2 is also observed. X-ray photoelectron spectroscopy (XPS) results show change in the surface states of titanium and oxygen. The observed antifogging properties are the direct results of the development of the superhydrophilic wetting characteristics to TiO2 films.

  3. Nuclear microscopy as a tool in TiO2 nanoparticles bioaccumulation studies in aquatic species

    NASA Astrophysics Data System (ADS)

    Pinheiro, Teresa; Moita, Liliana; Silva, Luís; Mendonça, Elsa; Picado, Ana

    2013-07-01

    Engineered Titanium nanoparticles are used for a wide range of applications from coatings, sunscreen cosmetic additives to solar cells or water treatment agents. Inevitably environmental exposure can be expected and data on the ecotoxicological evaluation of nanoparticles are still scarce. The potential effects of nanoparticles of titanium dioxide (TiO2) on two model organisms, the water flea, Daphnia magna and the duckweed Lemna minor, were examined in semichronic toxicity tests. Daphnia and Lemna were exposed to TiO2 nanoparticles (average particle size value of 28 ± 11 nm (n = 42); concentration range, 1.4-25 mg/L) by dietary route and growth in medium containing the nanoparticles of TiO2, respectively. Both morphology and microdistribution of Ti in the individuals were examined by nuclear microscopy techniques. A significant amount of TiO2 was found accumulated in Daphnia exposed to nanoparticles. Nuclear microscopy imaging revealed that Ti was localized only in the digestive tract of the Daphnia, which displayed difficulty in eliminating the nanoparticles from their body. Daphnia showed higher mortality when exposed to higher concentrations of TiO2 (>10 mg/L). The exposure to TiO2 nanoparticles above 25 mg/L caused morphological alterations in Lemna. The roots became stiff and fronds colorless. The Ti mapping of cross-sections of roots and fronds showed that Ti was mainly deposited in the epidermis of the fronds and roots, with minor internalization. In summary, exposure of aquatic organisms to TiO2 nanoparticles may alter the physiology of these organisms at individual and population levels, posing risks to aquatic ecosystems.

  4. Catalytic combustion of toluene on Pd/CeO2-TiO2 catalysts.

    PubMed

    Chen, Yu-Wen; Lee, Der-Shing

    2013-03-01

    Pd/TiO2 and Pd/CeO2 were reported to be very active to destruct toluene. Combination of TiO2 and CeO2 is an interesting candidate to achieve a catalyst with higher activity. In this study, a series of Pd/CeO2-TiO2 catalysts with various Pd loadings were prepared. CeO2-TiO2 was prepared by impregnation of aqueous solution of cerium nitrate into TiO2 support. It was then calcined at 400 degrees C. Pd was loaded by incipient-wetness impregnation method. The Pd loadings in all samples were fixed at 0.5 wt.%. The catalysts were characterized by powder X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, temperature-programmed reduction of hydrogen, and X-ray photoelectron spectroscopy. The catalysts were tested for total oxidation of toluene. The feed concentration of toluene was 8.564 g/m3 (2085 ppm), with GHSV = 10,000 h(-1). Pd particle sizes were 3-5 nm and well-dispersed on the support. CeO2 on TiO2 was easier to reduce than the bulk CeO2, therefore it could enhance the activity of VOC destruction. Pd/CeO2-TiO2 was more active than Pd/CeO2 and Pd/TiO2. Pd/CeO2-TiO2 with Ce/Ti ratio of 2/8 was very active for toluene destruction, due to its lower oxygen reduction temperature of ceria and higher concentration of Pd(0). PMID:23755662

  5. Surface modification of mixed-phase hydrogenated TiO2 and corresponding photocatalytic response

    NASA Astrophysics Data System (ADS)

    Samsudin, Emy Marlina; Hamid, Sharifah Bee Abd; Juan, Joon Ching; Basirun, Wan Jefrey; Kandjani, Ahmad Esmaeiljadeh

    2015-12-01

    Preparation of highly photo-activated TiO2 is achievable by hydrogenation at constant temperature and pressure, with controlled hydrogenation duration. The formation of surface disorders and Ti3+ is responsible for the color change from white unhydrogenated TiO2 to bluish-gray hydrogenated TiO2. This color change, together with increased oxygen vacancies and Ti3+ enhanced the solar light absorption from UV to infra-red region. Interestingly, no band gap narrowing is observed. The photocatalytic activity in the UV and visible region is controlled by Ti3+ and oxygen vacancies respectively. Both Ti3+ and oxygen vacancies increases the electron density on the catalyst surface thus facilitates rad OH radicals formation. The lifespan of surface photo-excited electrons and holes are also sustained thus prevents charge carrier recombination. However, excessive amount of oxygen vacancies deteriorates the photocatalytic activity as it serves as charge traps. Hydrogenation of TiO2 also promotes the growth of active {0 0 1} facets and facilitates the photocatalytic activity by higher concentration of surface OH radicals. However, the growth of {0 0 1} facets is small and insignificant toward the overall photo-kinetics. This work also shows that larger role is played by Ti3+ and oxygen vacancies rather than the surface disorders created during the hydrogenation process. It also demonstrates the ability of hydrogenated TiO2 to absorb wider range of photons even though at a similar band gap as unhydrogenated TiO2. In addition, the photocatalytic activity is shown to be decreased for extended hydrogenation duration due to excessive catalyst growth and loss in the total surface area. Thus, a balance in the physico-chemical properties of hydrogenated TiO2 is crucial to enhance the photocatalytic activity by simply controlling the hydrogenation duration.

  6. High photocatalytic activity of mixed anatase-rutile phases on commercial TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ruu Siah, Wai; Lintang, Hendrik O.; Shamsuddin, Mustaffa; Yuliati, Leny

    2016-02-01

    Titanium dioxide (TiO2) is well-known as an active photocatalyst for degradation of various organic pollutants. Over the years, a wide range of TiO2 nanoparticles with different phase compositions, crystallinities, and surface areas have been developed. Due to the different methods and conditions used to synthesize these commercial TiO2 nanoparticles, the properties and photocatalytic performance would also be different from each other. In this study, the photocatalytic removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5- trichlorophenoxyacetic acid (2,4,5-T) was investigated on commercial Evonik P25, Evonik P90, Hombikat UV100 and Hombikat N100 TiO2 nanoparticles. Upon photocatalytic tests, it was found that overall, the photocatalytic activities of the P25 and the P90 were higher than the N100 and the UV100 for the removal of both 2,4-D and 2,4,5-T. The high activities of the P25 and the P90 could be attributed to their phase compositions, which are made up of a mixture of anatase and rutile phases of TiO2. Whereas, the UV100 and the N100 are made up of 100% anatase phase of TiO2. The synergistic effect of the anatase/rutile mixture was reported to slow down the recombination rate of photogenerated electron-hole pairs. Consequently, the photocatalytic activity was increased on these TiO2 nanoparticles.

  7. Genetic variation influences immune responses in sensitive rats following exposure to TiO2 nanoparticles.

    PubMed

    Gustafsson, Asa; Jonasson, Sofia; Sandström, Thomas; Lorentzen, Johnny C; Bucht, Anders

    2014-12-01

    This study examines the immunological responses in rats following inhalation to titanium dioxide nanoparticles (TiO2 NPs), in naïve rats and in rats with induced allergic airway disease. The responses of two different inbred rat strains were compared: the Dark Aguoti (DA), susceptible to chronic inflammatory disorders, and the Brown Norwegian (BN), susceptible to atopic allergic inflammation. Naïve rats were exposed to an aerosol of TiO2 NPs once daily for 10 days. Another subset of rats was sensitized to the allergen ovalbumin (OVA) in order to induce airway inflammation. These sensitized rats were exposed to TiO2 NPs before and during the allergen challenge. Naïve rats exposed to TiO2 NPs developed an increase of neutrophils and lymphocytes in both rat strains. Airway hyperreactivity and production of inflammatory mediators typical of a T helper 1 type immune response were significantly increased, only in DA rats. Sensitization of the rats induced a prominent OVA-specific-IgE and IgG response in the BN rat while DA rats only showed an increased IgG response. Sensitized rats of both strains developed airway eosinophilia following allergen challenge, which declined upon exposure to TiO2 NPs. The level of neutrophils and lymphocytes increased upon exposure to TiO2 NPs in the airways of DA rats but remained unchanged in the airways of BN rats. In conclusion, the responses to TiO2 NPs were strain-dependent, indicating that genetics play a role in both immune and airway reactivity. DA rats were found to be higher responder compared to BN rats, both when it comes to responses in naïve and sensitized rats. The impact of genetically determined factors influencing the inflammatory reactions pinpoints the complexity of assessing health risks associated with nanoparticle exposures.

  8. Anatase TiO2 nanorod-decoration for highly efficient photoenergy conversion

    NASA Astrophysics Data System (ADS)

    Kim, Dong Hoe; Seong, Won Mo; Park, Ik Jae; Yoo, Eun-Sang; Shin, Seong Sik; Kim, Ju Seong; Jung, Hyun Suk; Lee, Sangwook; Hong, Kug Sun

    2013-11-01

    In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries.In recent studies of inorganic materials for energy applications, surface modification processes have been shown to be among the most effective methods to enhance the performance of devices. Here, we demonstrate a facile nano-decoration method which is generally applicable to anatase TiO2 nanostructures, as well as a nano-decorated hierarchical TiO2 nanostructure which improves the energy conversion efficiency of a dye-sensitized solar cell (DSSC). Using a facile sol-gel method, 0-D, 1-D, and 2-D type anatase TiO2 nanostructures were decorated with 200 nm long anatase TiO2 nanorods to create various hierarchical nanostructures. A structural analysis reveals that the branched nanorod has a highly crystalline anatase phase with anisotropic growth in the [001] longitudinal direction. When one of the hierarchical structures, a chestnut bur-like nanostructure, was employed in a dye-sensitized solar cell as a scattering layer, offering increased dye-loading properties, preserving a sufficient level of light-scattering ability and preserving superior charge transport and recombination properties as well, the energy conversion efficiency of the cell improved by 19% (from 7.16% to 9.09%) compared to a cell with a 0-D TiO2 sphere as a scattering layer. This generally applicable anatase nanorod-decorating method offers potential applications in various energy-conversion applications, especially in DSSCs, quantum-dot solar cells, photoelectrochemical water-splitting devices, photocatalysis, and lithium ion batteries. Electronic supplementary information (ESI) available: XRD of three types of TiO2 hosts, TEM images of nanorod-decorated TiO2 hierarchical nanostructures and host 0S-TiO2, reflectance of the free-standing TiO2 nanorod, SEM images of photoelectrodes employing various scattering layers with tmax, the amount of adsorbed dye molecules per surface volume on 0S and BS monolayer films, J-V curves of the DSSCs employing each active layer with tmax thickness, the transport time constants and recombination time constants versus various scattering layer thicknesses at constant Jsc (Jsc = 0.5 mA cm-2) and the photovoltaic parameters of each DSSC employing each tmax of various scattering layers. See DOI: 10.1039/c3nr03439a

  9. Preparation of flexible TiO2 photoelectrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Wen-Ren; Wang, Hsiu-Hsuan; Lin, Chia-Feng; Su, Chaochin

    2014-09-01

    Dye-sensitized solar cells (DSSCs) based on nanocrystalline TiO2 photoelectrodes on indium tin oxide (ITO) coated polymer substrates have drawn great attention due to its lightweight, flexibility and advantages in commercial applications. However, the thermal instability of polymer substrates limits the process temperature to below 150 °C. In order to assure high and firm interparticle connection between TiO2 nanocrystals (TiO2-NC) and polymer substrates, the post-treatment of flexible TiO2 photoelectrodes (F-TiO2-PE) by mechanical compression was employed. In this work, Degussa P25 TiO2-NC was mixed with tert-butyl alcohol and DI-water to form TiO2 paste. F-TiO2-PE was then prepared by coating the TiO2 paste onto ITO coated polyethylene terephthalate (PET) substrate using doctor blade followed by low temperature sintering at 120 °C for 2 hours. To study the effect of mechanical compression, we applied 50 and 100 kg/cm2 pressure on TiO2/PET to complete the fabrication of F-TiO2-PE. The surface morphology of F-TiO2-PE was characterized using scanning electron microscopy. The resultant F-TiO2-PE sample exhibited a smooth, crack-free structure indicating the great improvement in the interparticle connection of TiO2-NC. Increase of compression pressure could lead to the increase of DSSC photoconversion efficiency. The best photoconversion efficiency of 4.19 % (open circuit voltage (Voc) = 0.79 V, short-circuit photocurrent density (Jsc) = 7.75 mA/cm2, fill factor (FF) = 0.68) was obtained for the F-TiO2-PE device, which showed great enhancement compared with the F-TiO2-PE cell without compression treatment. The effect of compression in DSSC performance was vindicated by the electrochemical impedance spectroscopy measurement.

  10. Sol-gel TiO2 films as NO2 gas sensors

    NASA Astrophysics Data System (ADS)

    Georgieva, V.; Gadjanova, V.; Grechnikov, A.; Donkov, N.; Sendova-Vassileva, M.; Stefanov, P.; Kirilov, R.

    2014-05-01

    TiO2 films were prepared by a sol-gel technique with commercial TiO2 powder as a source material (P25 Degussa AG). After a special treatment, printing paste was prepared. The TiO2 layers were formed by means of drop-coating on Si-control wafers and on the Au-electrodes of quartz resonators. The surface morphology of the films was examined by scanning electron microscopy (SEM). Their structure was studied by Raman spectroscopy and the surface composition was determined by X-ray photoelectron spectroscopy (XPS). The layers had a grain-like surface morphology and consisted mainly of anatase TiO2 phase. The sensitivity of the TiO2 films to NO2 was assessed by the quartz crystal microbalance (QCM) technique. To this end, the films were deposited on both sides of a 16-MHz QCM. The sensing characteristic of the TiO2-QCM structure was investigated by measuring the resonant frequency shift (ΔF) of the QCM due to the mass loading caused by NO2 adsorption. The Sauerbrey equation was applied to establish the correlation between the QCM frequency changes measured after exposure to different NO2 concentrations and the mass-loading of the QCM. The experiments were carried out in a dynamic mode on a special laboratory setup with complete control of the process parameters. The TiO2 films were tested in the NO2 concentration interval from 10 ppm to 5000 ppm. It was found that a TiO2 loading of the QCM by 5.76 kHz corresponded to a system sensitive to NO2 concentrations above 250 ppm. On the basis of the frequency-time characteristics (FTCs) measured, AF at different NO2 concentrations was defined, the adsorption/desorption cycles were studied and the response and recovery times were estimated. The results obtained show that the process is reversible in the NO2 interval investigated. The results further suggested that TiO2 films prepared by a sol-gel method on a QCM can be used as a sensor element for NO2 detection.

  11. Structural and electrical properties of TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Rao, M. C.; Ravindranadh, K.; Shekhawat, M. S.

    2016-05-01

    Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. Titanium dioxide (TiO2) is traditionally the most widely used white pigment due to its high refractive index. TiO2 has received considerable attention and it has been used for optical coatings, photo-catalysis agents, gas sensors and solar cells. In this work, nano-structured TiO2 thin films were grown by pulsed laser deposition (PLD) technique on glass substrates. The prepared thin films were annealed from 400-600 °C in air for a period of 2 hours. Effect of annealing on the structural and electrical properties was studied. X-ray diffraction pattern exhibits peaks correspond to tetragonal anatase phase of TiO2 and the evaluated average crystallite size of the prepared materials are in the range of 16 to 30 nm. Electrical properties of the prepared samples are analyzed.

  12. Facile Synthesis of Robust Free-Standing TiO2 Nanotubular Membranes for Biofiltration Applications.

    PubMed

    Schweicher, Julien; Desai, Tejal A

    2014-03-01

    Robust monodisperse nanoporous membranes have a wide range of biotechnological applications, but are often difficult or costly to fabricate. Here, a simple technique is reported to produce free-standing TiO2 nanotubular membranes with through-hole morphology. It consists in a 3-step anodization procedure carried out at room temperature on a Ti foil. The first anodization (1 h at 80 V) is used to pattern the surface of the metallic foil. Then, the second anodization (24 h at 80 V) produces the array of TiO2 nanotubes that will constitute the final membrane. A higher voltage anodization (3-5 minutes at 180 V) is finally applied to detach the TiO2 nanotubular layer from the underlying Ti foil. In order to completely remove the barrier layer that obstructs some pores of the membrane, the latter is etched 2 minutes in a buffered oxide etch solution. The overall process produces 60 μm-thick TiO2 nanotubular membranes with tube openings of 110 nm on one side and 73 nm on the other side. The through-hole morphology of these membranes has been verified by performing diffusion experiments with glucose, insulin and immunoglobulin G where in differences in diffusion rate are observed based on molecular weight. Such biocompatible TiO2 nanotubular membranes, with controlled pore size and morphology, have broad biotechnological and biomedical applications. PMID:24634542

  13. TiO2 microboxes with controlled internal porosity for high-performance lithium storage

    DOE PAGES

    Gao, Xuehui; Li, Gaoran; Xu, Yangyang; Hong, Zhanglian; Liang, Chengdu; Lin, Zhan

    2015-10-02

    Titanium dioxide (TiO2) is considered a promising anode material for high-power lithium ion batteries (LIBs) because of its low cost, high thermal/chemical stability, and good safety performance without solid electrolyte interface formation. However, the poor electronic conductivity and low lithium ion diffusivity of TiO2 result in poor cyclability and lithium ion depletion at high current rates, which hinder them from practical applications. Herein we demonstrate that hierarchically structured TiO2 microboxes with controlled internal porosity can address the aforementioned problems for high-power, long-life LIB anodes. A self-templating method for the synthesis of mesoporous microboxes was developed through Na2EDTA-assisted ion exchange ofmore » CaTiO3 microcubes. The resulting TiO2 nanorods were organized into microboxes that resemble the microcube precursors. Furthermore, this nanostructured TiO2 material has superior lithium storage properties with a capacity of 187 mAh g-1 after 300 cycles at 1C and good rate capabilities up to 20C.« less

  14. TiO2 Thin Film via Sol-Gel Method: Investigation on Molarity Effect

    NASA Astrophysics Data System (ADS)

    Mohamad Saad, Puteri Sarah; Sutan, Hanis Binti; Sobihana Shariffudin, Shafinaz; Hashim, Hashimah; Mohd Noor, Uzer

    2015-11-01

    We have systematically investigated the current-voltage (I-V), absorbance and optical band gap of TiO2 thin film prepared through varying the molarity of the TiO2 precursor by sol-gel spin coating technique. In addition to the electrical and optical characteristics, the surface morphology was examined by using Atomic Force Microscope (AFM). From the image of the AFM, we were able to observe the uniformity of the TiO2 thin film. From the experimental results, we found that the uniformity of the TiO2 thin film is optimized at 0.2M sample. It is also found that, as the molarity increased, there is tendency of the resistivity to decrease. Not only that, the absorbance measurement and optical band gap also gave its best value for 0.2M sample. Therefore, in this work it is concluded that 0.20M of TiO2 gave the best characteristics for all measurements.

  15. Functionalization of TiO2 with graphene quantum dots for efficient photocatalytic hydrogen evolution

    NASA Astrophysics Data System (ADS)

    Hao, Xuqiang; Jin, Zhiliang; Xu, Jing; Min, Shixiong; Lu, Gongxuan

    2016-06-01

    Graphene quantum dots (GQDs) serve as a novel solid-state electron transfer reagent anchored on TiO2 by in situ photo-assisted strategy and greatly enhanced photocatalytic H2 evolution activity in methanol aqueous solution without the noble mental cocatalyst. The excellent photocatalytic activities were ascribed to the GQDs which act as an excellent electron transporters and acceptors, as well as photosensitizer. GQDs not only acted as efficient electron reservoirs and a solid-state electron transfer reagent from the conduction band of TiO2 to GQDs, but also acted as an excellent photosensitizer to sensitize TiO2, in which the photoinduced electrons transfer from excited GQDs to TiO2 to produce H2. In addition, GQDs is nanoscale fragments of graphene which can provide a larger active surface and greatly increase the contact area with the TiO2, which is conducive to rapidly transfer photo-generated electrons due to the large specific area and high carrier mobility of GQDs. Thus, GQDs improved the photocatalytic activity for H2 evolution.

  16. Bioactive TiO2 fiber films prepared by electrospinning method.

    PubMed

    Chen, S J; Yu, H Y; Yang, B C

    2013-01-01

    Electrospining method was used to prepare bioactive TiO(2) fibers films in this study. The acetic acid/ethanol/tetrabutyl titanate/polyvinylpyrrolidone (PVP) solvent system was used as precursor for the electrospining. The TiO(2) fiber structures (including its fiber diameter, morphology, and phase composition) could be controlled by changing feeding rate, PVP concentration and sinter temperature. The fiber films were subjected to simulated body fluid soaking experiments and MG63 cells culture experiments to study their bioactivity. According to the X-ray diffraction and MTT assay results, the fiber containing with anatase showed better apatite formation ability than that without anatase at the early stage, while cell proliferated on anatase-rutile TiO(2) fiber was better than that on other samples (p < 0.05).Some string beads in the fiber were beneficial for apatite formation, while the cell proliferated best on the fiber film without string beads (p < 0.05). The fiber with a diameter of 200 nm had the best apatite formation ability and osteoblast compatibility (p < 0.05). The results showed that the TiO(2) fiber film structure had great influence on its bioactivity. It indicated that the electronspining method is an effective way to prepare bioactive titania fiber films, and it is possible to control the structure of the films in the spinning process to optimize the bioactivity of TiO(2) fiber.

  17. Aggregation and deposition of engineered TiO2 nanoparticles in natural fresh and brackish waters

    NASA Astrophysics Data System (ADS)

    Sillanpää, Markus; Paunu, Tiina-Mari; Sainio, Pirjo

    2011-07-01

    The use and thus environmental release potential of metal-based nanoparticles have rapidly increased. Due to their size-dependent new properties, the fate and effect of nanomaterial may differ from those of the conventional form of corresponding material. The agglomeration and sedimentation were studied by spiking the TiO2-P25 particles in natural fresh and brackish water samples. The natural waters were determined for conductivity, pH, salinity, total organic carbon, turbidity, common nutrients and trace elements. The hydrodynamic diameter and concentration of TiO2-P25 particle dispersions were monitored by using a dynamic light scattering and a spectrophotometer, respectively. The experiments were performed at two particle concentrations 100 mg/l and 1 mg/l (10 mg/l for deposition studies). The aggregation rates in brackish waters were clearly higher in higher initial concentration and the sedimentation of aggregates decreased the TiO2 concentration down to 20% and 80% of initial higher and lower concentrations, respectively. One fresh water sample favoured the destabilisation of TiO2-P25 particles whereas another fresh water sample stabilised the TiO2 particle dispersion. The aggregation had a strong dependence on the particle concentration. High ionic content of brackish water probably explains the formation of aggregates, whereas organic substances and pH may account for the different agglomeration behaviour in fresh waters.

  18. TiO2/EVOH based reactive interlayer in Surlyn for organic device encapsulation

    NASA Astrophysics Data System (ADS)

    Kopanati, Gayathri N.; Ramamurthy, Praveen C.; Madras, Giridhar

    2016-02-01

    Barrier materials are important for improving the stability and lifetimes of organic electronic devices. A simple technique for improving the barrier properties of polymer films was considered in this work by using TiO2 nanoparticles in the interlayer to be incorporated in the polymer film. TiO2 was synthesized by the solution combustion technique, was further functionalized using stearic acid or octadecylamine to induce hydrophobicity and enhance processing of the composite interlayer. The grafting of these compounds on to TiO2 was investigated using Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis and thermo-gravimetric analysis. The functionalized and neat TiO2 were blended with poly (vinyl alcohol-ethylene) (EVOH) and were melt compressed between Surlyn films. The resulting nanocomposite films were tested for their transparency and barrier properties using UV-visible spectroscopy and calcium degradation test, respectively. Further, the effectiveness of these barrier films in encapsulating organic devices was determined from accelerated aging tests. Therefore, the synthesized barrier films with neat and functionalized TiO2 in the interlayers proved to be effective as moisture barrier composite films.

  19. Paramagnetic behavior of Co doped TiO2 nanocrystals controlled by self-purification mechanism

    NASA Astrophysics Data System (ADS)

    Anitha, B.; Khadar, M. Abdul; Banerjee, Alok

    2016-07-01

    Doping in nanocrystals is a challenging process because of the self- purification mechanism which tends to segregate out the dopants resulting in a greater dopant concentration near the surface than at the interior of nanocrystals. In the present work nanocrystals of TiO2 doped with different atom % of Co were synthesized by peroxide gel method. XRD analysis confirmed the tetragonal anatase structure and HRTEM images showed the rod-like morphology of the samples. Raman modes of anatase phase of TiO2 along with weak intensity peaks of Co3O4 for higher Co dopant concentrations were observed for the samples. EPR measurements revealed the presence of cobalt in +2 oxidation state in the TiO2 matrix. SQUID measurements indicated paramagnetic behavior of the Co doped TiO2 nanocrystals. The paramagnetic behavior is attributed to an increased concentration of Co2+ ions and an increased presence of Co3O4 phase near the surface of the TiO2 nanocrystals due to self-purification mechanism.

  20. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    PubMed

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-01

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells. PMID:26953635

  1. Thermoelectric Properties of Self Assemble TiO2/SnO2 Nanocomposites

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 (mu)W/m sq K at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  2. Thermoelectric Properties of Self Assembled TiO2/SnO2 Nanocomposites

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Sayir, Ali; Sehirlioglu, Alp

    2008-01-01

    Recent advances in improving efficiency of thermoelectric materials are linked to nanotechnology. Thermodynamically driven spinodal decomposition was utilized to synthesize bulk nanocomposites. TiO2/SnO2 system exhibits a large spinodal region, ranging from 15 to 85 mole % TiO2. The phase separated microstructures are stable up to 1400 C. Semiconducting TiO2/SnO2 powders were synthesized by solid state reaction between TiO2 and SnO2. High density samples were fabricated by pressureless sintering. Self assemble nanocomposites were achieved by annealing at 1000 to 1350 C. X-ray diffraction reveal phase separation of (Ti(x)Sn(1-x))O2 type phases. The TiO2/SnO2 nanocomposites exhibit n-type behavior; a power factor of 70 W/mK2 at 1000 C has been achieved with penta-valent doping. Seebeck, thermal conductivity, electrical resistivity and microstructure will be discussed in relation to composition and doping.

  3. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    PubMed

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials. PMID:27381513

  4. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    NASA Astrophysics Data System (ADS)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-06-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage (I-V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  5. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE PAGES

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

  6. 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.

  7. Both Enhanced Biocompatibility and Antibacterial Activity in Ag-Decorated TiO2 Nanotubes

    PubMed Central

    Lan, Ming-Ying; Liu, Chia-Pei; Huang, Her-Hsiung; Lee, Sheng-Wei

    2013-01-01

    In this study, Ag is electron-beam evaporated to modify the topography of anodic TiO2 nanotubes of different diameters to obtain an implant with enhanced antibacterial activity and biocompatibility. We found that highly hydrophilic as-grown TiO2 nanotubes became poorly hydrophilic with Ag incorporation; however they could effectively recover their wettability to some extent under ultraviolet light irradiation. The results obtained from antibacterial tests suggested that the Ag-decorated TiO2 nanotubes could greatly inhibit the growth of Staphylococcus aureus. In vitro biocompatibility evaluation indicated that fibroblast cells exhibited an obvious diameter-dependent behavior on both as-grown and Ag-decorated TiO2 nanotubes. Most importantly, of all samples, the smallest diameter (25-nm-diameter) Ag-decorated nanotubes exhibited the most obvious biological activity in promoting adhesion and proliferation of human fibroblasts, and this activity could be attributed to the highly irregular topography on a nanometric scale of the Ag-decorated nanotube surface. These experimental results demonstrate that by properly controlling the structural parameters of Ag-decorated TiO2 nanotubes, an implant surface can be produced that enhances biocompatibility and simultaneously boosts antibacterial activity. PMID:24124484

  8. Atomistic Simulation Studies of the Bulk Lithiated TiO2

    NASA Astrophysics Data System (ADS)

    Ngoepe, Phuti; Matshaba, Malili; Sayle, Dean

    2013-03-01

    TiO2 has been confirmed as a safe anode material in lithium ion batteries due to its higher Li-insertion potential, (1.5V) in comparison with commercialised carbon anode materials. In the current study, amorphisation recrystallization method is used to produce bulk TiO2 with a brookite structure and lithium is inserted at different concentrations. In accordance with pair distribution function experiments, it is found that lithiation tends to amorphise the structures. Simulated X-ray diffraction patterns are produced from such structures and compared with the experimental XRDs. Microstructures of TiO2 are generated and are found to be highly twinned hence forming straight and zigzag tunnels. The microstructures of lithiated TiO2 display limited twinning and tunnels with less pathways available for lithium transport. The microstructures are compared with those of nanostructural TiO2 and suggestions for the preference of the latter in anodes are put forward. SARChI Chair, under the National Research Foundation, Pretoria

  9. Synthesis and photocatalytic activities of Nd-doped TiO2 mesoporous microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xijian; Sun, Yangang; Wang, Yeying; Zhang, Lijuan; Lu, Jie

    2016-11-01

    Nd-doped TiO2 mesoporous microspheres with possessing regular micro/nanostructure were synthesized by a simple and facile method. The structure and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms and UV-Visible absorbance spectroscopy. It was revealed that Nd-doped TiO2 mesoporous microspheres are composed of primary nanoparticles with a particle size of ˜25nm. The photocatalytic activities of all the samples were evaluated by degradation methyl orange (MO) in aqueous solution as a model reaction under xenon lamp light irradiation. The results showed that the doped samples demonstrated a higher photocatalytic activity than TiO2 mesoporous microspheres, and the MO of 10mg/mL almost could be completely degraded by the Nd-doped TiO2 mesoporous sample (the dosage of Nd salt to TiO2 is 6%) under xenon lamp light irradiation within 1h.

  10. Kinetics and mechanism of TNT degradation in TiO2 photocatalysis.

    PubMed

    Son, Hyun-Seok; Lee, So-Jin; Cho, Il-Hyoung; Zoh, Kyung-Duk

    2004-10-01

    The photocatalytic degradation of TNT in a circular photocatalytic reactor, using a UV lamp as a light source and TiO(2) as a photocatalyst, was investigated. The effects of various parameters such as the initial TNT concentration, and the initial pH on the TNT degradation rate of TiO(2) photocatalysis were examined. In the presence of both UV light illumination and TiO(2) catalyst, TNT was more effectively degraded than with either UV or TiO(2) alone. The reaction rate was found to obey pseudo first-order kinetics represented by the Langmuir-Hinshelwood model. In the mineralization study, TNT (30 mg/l) photocatalytic degradation resulted in an approximately 80% TOC decrease after 150 min, and 10% of acetate and 57% of formate were produced as the organic intermediates, and were further degraded. NO(-)(3) NO(-)(2), and NH(+)(4) were detected as the nitrogen byproducts from photocatalysis and photolysis, and more than 50% of the total nitrogen was converted mainly to NO(-)(3)in the photocatalysis. However, NO(-)(3) did not adsorbed on the TiO(2) surface. TNT showed higher photocatalytic degradation efficiency at neutral and basic pH.

  11. Efficient bioconversion of rice straw to ethanol with TiO2/UV pretreatment.

    PubMed

    Kang, Hee-Kyoung; Kim, Doman

    2012-01-01

    Rice straw is a lignocellulosic biomass that constitutes a renewable organic substance and alternative source of energy; however, its structure confounds the liberation of monosaccharides. Pretreating rice straw using a TiO(2)/UV system facilitated its hydrolysis with Accellerase 1000(™), suggesting that hydroxyl radicals (OH·) from the TiO(2)/UV system could degrade lignin and carbohydrates. TiO(2)/UV pretreatment was an essential step for conversion of hemicellulose to xylose; optimal conditions for this conversion were a TiO(2) concentration of 0.1% (w/v) and an irradiation time of 2 h with a UV-C lamp at 254 nm. After enzymatic hydrolysis, the sugar yields from rice straw pretreated with these parameters were 59.8 ± 0.7% of the theoretical for glucose (339 ± 13 mg/g rice straw) and 50.3 ± 2.8% for xylose (64 ± 3 mg/g rice straw). The fermentation of enzymatic hydrolysates containing 10.5 g glucose/L and 3.2 g xylose/L with Pichia stipitis produced 3.9 g ethanol/L with a corresponding yield of 0.39 g/g rice straw. The maximum possible ethanol conversion rate is 76.47%. TiO(2)/UV pretreatment can be performed at room temperature and atmospheric pressure and demonstrates potential in large-scale production of fermentable sugars. PMID:21909680

  12. Microstructure design of nanoporous TiO2 photoelectrodes for dye-sensitized solar cell modules.

    PubMed

    Hu, Linhua; Dai, Songyuan; Weng, Jian; Xiao, Shangfeng; Sui, Yifeng; Huang, Yang; Chen, Shuanghong; Kong, Fantai; Pan, Xu; Liang, Linyun; Wang, Kongjia

    2007-01-18

    The optimization of dye-sensitized solar cells, especially the design of nanoporous TiO2 film microstructure, is an urgent problem for high efficiency and future commercial applications. However, up to now, little attention has been focused on the design of nanoporous TiO2 microstructure for a high efficiency of dye-sensitized solar cell modules. The optimization and design of TiO2 photoelectrode microstructure are discussed in this paper. TiO2 photoelectrodes with three different layers, including layers of small pore size films, larger pore size films, and light-scattering particles on the conducting glass with the desirable thickness, were designed and investigated. Moreover, the photovoltaic properties showed that the different porosities, pore size distribution, and BET surface area of each layer have a dramatic influence on short-circuit current, open-circuit voltage, and fill factor of the modules. The optimization and design of TiO2 photoelectrode microstructure contribute a high efficiency of DSC modules. The photoelectric conversion efficiency around 6% with 15 x 20 cm2 modules under illumination of simulated AM1.5 sunlight (100 mW/cm2) and 40 x 60 cm2 panels with the same performance tested outdoor have been achieved by our group.

  13. Structural, electrical and optical properties of TiO 2 doped WO 3 thin films

    NASA Astrophysics Data System (ADS)

    Patil, P. S.; Mujawar, S. H.; Inamdar, A. I.; Shinde, P. S.; Deshmukh, H. P.; Sadale, S. B.

    2005-12-01

    TiO 2 doped WO 3 thin films were deposited onto glass substrates and fluorine doped tin oxide (FTO) coated conducting glass substrates, maintained at 500 °C by pyrolytic decomposition of adequate precursor solution. Equimolar ammonium tungstate ((NH 4) 2WO 4) and titanyl acetyl acetonate (TiAcAc) solutions were mixed together at pH 9 in volume proportions and used as a precursor solution for the deposition of TiO 2 doped WO 3 thin films. Doping concentrations were varied between 4 and 38%. The effect of TiO 2 doping concentration on structural, electrical and optical properties of TiO 2 doped WO 3 thin films were studied. Values of room temperature electrical resistivity, thermoelectric power and band gap energy ( Eg) were estimated. The films with 38% TiO 2 doping in WO 3 exhibited lowest resistivity, n-type electrical conductivity and improved electrochromic performance among all the samples. The values of thermoelectric power (TEP) were in the range of 23-56 μV/K and the direct band gap energy varied between 2.72 and 2.86 eV.

  14. Enhancing antimicrobial activity of TiO2/Ti by torularhodin bioinspired surface modification.

    PubMed

    Ungureanu, Camelia; Dumitriu, Cristina; Popescu, Simona; Enculescu, Monica; Tofan, Vlad; Popescu, Marian; Pirvu, Cristian

    2016-02-01

    Implant-associated infections are a major cause of morbidity and mortality. This study was performed using titanium samples coated by anodization with a titanium dioxide (TiO2) shielded nanotube layer. TiO2/Ti surface was modified by simple immersion in torularhodin solution and by using a mussel-inspired method based on polydopamine as bio adhesive for torularhodin immobilization. SEM analysis revealed tubular microstructures of torularhodin and the PDA ability to function as a catchy anchor between torularhodin and TiO2 surface. Corrosion resistance was associated with TiO2 barrier oxide layer and nano-organized oxide layer and the torularhodin surface modification does not bring significant changes in resistance of the oxide layer. Our results demonstrated that the torularhodin modified TiO2/Ti surface could effectively prevent adhesion and proliferation of Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and Pseudomonas aeruginosa. The new modified titanium surface showed good biocompatibility and well-behaved haemocompatibility. This biomaterial with enhanced antimicrobial activity holds great potential for future biomedical applications.

  15. Surface functionalization of cyclic olefin copolymer (COC) with evaporated TiO2 thin film

    NASA Astrophysics Data System (ADS)

    El Fissi, Lamia; Vandormael, Denis; Houssiau, Laurent; Francis, Laurent A.

    2016-02-01

    Cyclic olefin copolymer (COC) is a new class of thermoplastic polymers used for a variety of applications ranging from bio-sensing to optics. However, the hydrophobicity of native COC hampers the further development and application of this material [1]. In this work, we report the structural, morphological, and optical properties of the TiO2/COC hybrid material, which provides a desirable substrate for optical devices and subsequent surface modifications. The TiO2 film on COC substrate was deposited by the evaporation method, and it was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), profilometry and atomic force microscope (AFM). Using an UV-vis spectrophotometer, we found that the transmittance of the TiO2/COC hybrid material in the visible domain reached 80%. The TiO2/COC hybrid appeared to be stable in most of the assessed polar solvents and acid/basic solutions. The new TiO2/COC hybrid material and the robust fabrication method are expected to enable a variety of BioMEMS applications.

  16. Inkjet printed highly porous TiO2 films for improved electrical properties of photoanode.

    PubMed

    Bernacka-Wojcik, I; Wojcik, P J; Aguas, H; Fortunato, E; Martins, R

    2016-03-01

    The aim of presented work is to show the improvements obtained in the properties of TiO2 films for dye sensitized solar cells fabricated by inkjet printing using an innovative methodology. We describe the development and properties of TiO2-based inks used in a lab-scale printer, testing various commercial TiO2 pastes. The porosity of the deposited inkjet printed TiO2 films is much higher than using the conventional "doctor blade" deposition technique, as the ink solvent evaporates during the droplet fly from the nozzle to the substrate due to its picoliter volume and the applied heating of a printing stage (70°C). Thanks to higher surface area, the dye sensitized solar cells incorporating inkjet printed TiO2 film gave higher efficiencies (ηmax≈3.06%) than the more compact films obtained by the "doctor blade" method (ηmax≈2.56%). Furthermore, electrochemical analysis indicates that for whole tested thickness range, the inkjet printed layers have higher effective electron diffusion length indicating their better transport properties.

  17. Foldable and Cytocompatible Sol-gel TiO2 Photonics

    PubMed Central

    Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B.; Geiger, Sarah J.; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

    2015-01-01

    Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices. PMID:26344823

  18. Deliberate Design of TiO2 Nanostructures towards Superior Photovoltaic Cells.

    PubMed

    Sun, Ziqi; Liao, Ting; Sheng, Liyuan; Kou, Liangzhi; Kim, Jung Ho; Dou, Shi Xue

    2016-08-01

    TiO2 nanostructures are being sought after as flexibly utilizable building blocks for the fabrication of the mesoporous thin-film photoelectrodes that are the heart of the third-generation photovoltaic devices, such as dye-sensitized solar cells (DSSCs), quantum-dot-sensitized solar cells (QDSSCs), and the recently promoted perovskite-type solar cells. Here, we report deliberate tailoring of TiO2 nanostructures for superior photovoltaic cells. Morphology engineering of TiO2 nanostructures is realized by designing synthetic protocols in which the precursor hydrolysis, crystal growth, and oligomer self-organization are precisely controlled. TiO2 nanostructures in forms varying from isolated nanocubes, nanorods, and cross-linked nanorods to complex hierarchical structures and shape-defined mesoporous micro-/nanostructures were successfully synthesized. The photoanodes made from the shape-defined mesoporous TiO2 microspheres and nanospindles presented superior performances, owing to the well-defined overall shapes and the inner ordered nanochannels, which allow not only a high amount of dye uptake, but also improved visible-light absorption. This study provides a new way to seek an optimal synthetic protocol to meet the required functionality of the nanomaterials.

  19. Foldable and Cytocompatible Sol-gel TiO2 Photonics.

    PubMed

    Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B; Geiger, Sarah J; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

    2015-09-07

    Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

  20. Structure and Formation Mechanism of Black TiO2 Nanoparticles

    DOE PAGES

    Tian, Mengkun; Mahjouri-Samani, Masoud; Eres, Gyula; Sachan, Ritesh; Yoon, Mina; Chisholm, Matthew F.; Wang, Kai; Puretzky, Alexander A.; Rouleau, Christopher M.; Geohegan, David B.; et al

    2015-10-27

    The remarkable properties of black TiO2 are due to its disordered surface shell surrounding a crystalline core. However, the chemical composition and the atomic and electronic structure of the disordered shell and its relationship to the core remain poorly understood. Using advanced transmission electron microscopy methods, we show that the outermost layer of black TiO2 nanoparticles consists of a disordered Ti2O3 shell. The measurements show a transition region that connects the disordered Ti2O3 shell to the perfect rutile core consisting first of four to five monolayers of defective rutile, containing clearly visible Ti interstitial atoms, followed by an ordered reconstructionmore » layer of Ti interstitial atoms. Our data suggest that this reconstructed layer presents a template on which the disordered Ti2O3 layers form by interstitial diffusion of Ti ions. In contrast to recent reports that attribute TiO2 band-gap narrowing to the synergistic action of oxygen vacancies and surface disorder of nonspecific origin, our results point to Ti2O3, which is a narrow-band-gap semiconductor. In conclusion, as a stoichiometric compound of the lower oxidation state Ti3+ it is expected to be a more robust atomic structure than oxygen-deficient TiO2 for preserving and stabilizing Ti3+ surface species that are the key to the enhanced photocatalytic activity of black TiO2.« less

  1. Both enhanced biocompatibility and antibacterial activity in Ag-decorated TiO2 nanotubes.

    PubMed

    Lan, Ming-Ying; Liu, Chia-Pei; Huang, Her-Hsiung; Lee, Sheng-Wei

    2013-01-01

    In this study, Ag is electron-beam evaporated to modify the topography of anodic TiO2 nanotubes of different diameters to obtain an implant with enhanced antibacterial activity and biocompatibility. We found that highly hydrophilic as-grown TiO2 nanotubes became poorly hydrophilic with Ag incorporation; however they could effectively recover their wettability to some extent under ultraviolet light irradiation. The results obtained from antibacterial tests suggested that the Ag-decorated TiO2 nanotubes could greatly inhibit the growth of Staphylococcus aureus. In vitro biocompatibility evaluation indicated that fibroblast cells exhibited an obvious diameter-dependent behavior on both as-grown and Ag-decorated TiO2 nanotubes. Most importantly, of all samples, the smallest diameter (25-nm-diameter) Ag-decorated nanotubes exhibited the most obvious biological activity in promoting adhesion and proliferation of human fibroblasts, and this activity could be attributed to the highly irregular topography on a nanometric scale of the Ag-decorated nanotube surface. These experimental results demonstrate that by properly controlling the structural parameters of Ag-decorated TiO2 nanotubes, an implant surface can be produced that enhances biocompatibility and simultaneously boosts antibacterial activity.

  2. Comparative study of (N, Fe) doped TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Larumbe, S.; Monge, M.; Gómez-Polo, C.

    2015-02-01

    The effect of N and Fe doping on the structural, optical, photocatalytic and magnetic properties of TiO2 nanoparticles is analyzed. Undoped, N and Fe doped TiO2 nanoparticles were synthesized by sol-gel method. Titanium tetraisopropoxide (TTIP) was used as the alkoxyde precursor and iron (III) nitrate and urea were the employed precursors to obtain Fe and N doped TiO2 nanoparticles, respectively. Differential Scanning Calorimetry (DSC) and Thermogravimetrical Analysis (TGA) enabled the analysis of the thermal decomposition process and the final calcination temperature. X-Ray Diffraction patterns of the calcined nanoparticles displayed a monophasic anatase structure in all the samples with mean crystallite diameter around 4-6 nm. The introduction of Fe or N induced a red-shift in the absorption spectra. Such a red-shift is characterized by a decrease in the band-gap energy and the occurrence of an absorption (Urbach) tail in the visible region. Finally, the photocatalytic efficiency was evaluated under UV and Visible light, obtaining an improvement of the kinetic constants in the nitrogen doped TiO2 nanoparticles with respect to undoped and Fe doped TiO2. The differences in the photocatalytic response under Fe and N doping are also analyzed in terms of the magnetic response of the analyzed photocatalysts.

  3. Colloidal TiO2 nanocrystals prepared from peroxotitanium complex solutions: phase evolution from different precursors.

    PubMed

    Seok, Sang Il; Vithal, Muga; Chang, Jeong Ah

    2010-06-01

    We report the preparation of nanocrystalline anatase and rutile TiO(2) from aqueous peroxotitanium complex (PTC) solutions and their characterization by powder X-ray diffraction (XRD), infrared spectroscopy, and Raman spectroscopy. The phase evolution of TiO(2) prepared using PTC derived from different precursors, i.e., TiCl(4) and titanium tetraisopropoxide (TTIP), is related to the nature of the intermediate steps. Phase-pure nanoanatase was formed in PTC solution derived from TiCl(4), while a mixture of minor anatase and dominant rutile were prepared from PTC when TTIP was used as precursor. On the other hand, in the case of calcining PTC powders in air, a pure anatase phase of TiO(2) was obtained, regardless of the precursor used. Thus, the formation and attachment of hydrated TiO(6) units or TiO(2)·xH(2)O under a different environment, especially pH, plays a critical role in determining the phase during the crystallization of TiO(2). PMID:20227087

  4. Detecting HER2 on cancer cells by TiO2 spheres Mie scattering.

    PubMed

    Tsai, Min-Chiao; Tsai, Tsung-Lin; Shieh, Dar-Bin; Chiu, Hsin-Tien; Lee, Chi-Young

    2009-09-15

    This work is the first to describe a bioimaging method that uses highly uniformly sized TiO(2) submicrometer and micrometer spheres based on Mie scattering. Transmembrane proteins (HER2) located on the surface of cancer cells were detected by bonded antibody-linked TiO(2) spheres using optic microscopy and UV-vis spectroscopy. A particular HER2 bond on cancer cells, which has a weaker binding affinity than the biotin/avidin interaction, can be identified between TiO(2) spheres that are linked to anti-HER2 antibodies and those that are linked to nonspecific mouse IgG antibodies by observing the cells under an optical microscope or by measuring absorbance from a UV-vis spectrum. The TiO(2) spheres used in this work was prepared by reacting TTIP with carboxylic acid, as described elsewhere and the uniformity of the TiO(2) sphere was further improved by adjusting the amount of water used. The water content was inversely related to particle size and the size distribution: as more water was used, smaller spheres with a narrower size distribution were obtained. The most uniform sphere obtained had a diameter of about 1 microm with a size variation of 3%. PMID:19653662

  5. Efficient Electrochemical Reduction of Nitrobenzene by Defect-Engineered TiO2-x Single Crystals.

    PubMed

    Liu, Chang; Zhang, Ai-Yong; Pei, Dan-Ni; Yu, Han-Qing

    2016-05-17

    TiO2 is a typical semiconductor and has been extensively used as an effective photocatalyst for environmental pollution control. But it could not be used as an electrochemical reductive catalyst because of its low electric conductivity and electrocatalytic activity. In this work, however, we demonstrate that TiO2 can act as an excellent cathodic electrocatalyst when its crystal shape, exposed facet and oxygen-stoichiometry are finely tailored by the local geometric and electronic structures. The defect-engineered TiO2-x single crystals dominantly exposed by high-energy {001} facets exhibits a high cathodic activity and great stability for electrochemical reduction of nitrobenzene, a typical refractory pollutant with high toxicity in environment. The single crystalline structure, the high-energy {001} facet and the defective oxygen vacancy of the defect-engineered TiO2-x single crystals are found to be mainly responsible for their cathodic superiority. With the findings in this work, a more practical non-Pd cathodic electrocatalyst could be prepared and applied for electrocatalytic reduction of refractory pollutants in water and wastewater, and extend the promising applications of TiO2 in the fields of environmental science. PMID:27128346

  6. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls.

    PubMed

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g(-1)·h(-1) and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  7. Foldable and Cytocompatible Sol-gel TiO2 Photonics

    NASA Astrophysics Data System (ADS)

    Li, Lan; Zhang, Ping; Wang, Wei-Ming; Lin, Hongtao; Zerdoum, Aidan B.; Geiger, Sarah J.; Liu, Yangchen; Xiao, Nicholas; Zou, Yi; Ogbuu, Okechukwu; Du, Qingyang; Jia, Xinqiao; Li, Jingjing; Hu, Juejun

    2015-09-01

    Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

  8. Direct imaging of Pt single atoms adsorbed on TiO2 (110) surfaces.

    PubMed

    Chang, Teng-Yuan; Tanaka, Yusuke; Ishikawa, Ryo; Toyoura, Kazuaki; Matsunaga, Katsuyuki; Ikuhara, Yuichi; Shibata, Naoya

    2014-01-01

    Noble metal nanoparticles (e.g., gold and platinum) supported on TiO2 surfaces are utilized in many technological applications such as heterogeneous catalysts. To fully understand their enhanced catalytic activity, it is essential to unravel the interfacial interaction between the metal atoms and TiO2 surfaces at the level of atomic dimensions. However, it has been extremely difficult to directly characterize the atomic-scale structures that result when individual metal atoms are adsorbed on the TiO2 surfaces. Here, we show direct atomic-resolution images of individual Pt atoms adsorbed on TiO2 (110) surfaces using aberration-corrected scanning transmission electron microscopy. Subangstrom spatial resolution enables us to identify five different Pt atom adsorption sites on the TiO2 (110) surface. Combining this with systematic density functional theory calculations reveals that the most favorable Pt adsorption sites are on vacancy sites of basal oxygen atoms that are located in subsurface positions relative to the top surface bridging oxygen atoms.

  9. Plasmonic Effect in Au-Added TiO2-Based Solar Cell

    NASA Astrophysics Data System (ADS)

    Van Hong, Le; Cat, Do Tran; Chi, Le Ha; Thuy, Nguyen Thi; Van Hung, Tran; Tai, Ly Ngoc; Long, Pham Duy

    2016-10-01

    TiO2 nano thin films have been fabricated on fluoride tin oxide (FTO) film electrodes by hydrothermal synthesis at temperatures of 80°C, 120°C, 150°C, and 200°C for different synthesis times of 1 h, 2 h, and 3 h in 2.5 mol, 5 mol, and 7.5 mol NaOH solution. X-ray diffraction patterns and field-emission scanning electron microscopy (FESEM) images were recorded for all the film samples, and the results confirmed that TiO2 anatase phase was generally formed in nanowire form. The influence of synthesis temperature, processing time, and NaOH content on the structure and morphology of the TiO2 material was studied. Au nanoparticles with size of around 2 × 10-8 m were added into the TiO2 thin films by thermal evaporation in vacuum combined with thermal annealing. Based on photocurrent-voltage ( I- V) characteristics measured under irradiation with visible light, the short-circuit current, open-circuit voltage, and efficiency of solar cells with FTO/Au-added TiO2/(I-/I2-) electrolyte/Pt configuration were evaluated. The short-circuit current and efficiency of the Au-added solar cell were greatly improved, which is supposed to be related to a contribution of the surface plasmon resonance effect.

  10. Comparisons between TiO2- and SiO2-flux assisted TIG welding processes.

    PubMed

    Tseng, Kuang-Hung; Chen, Kuan-Lung

    2012-08-01

    This study investigates the effects of flux compounds on the weld shape, ferrite content, and hardness profile in the tungsten inert gas (TIG) welding of 6 mm-thick austenitic 316 L stainless steel plates, using TiO2 and SiO2 powders as the activated fluxes. The metallurgical characterizations of weld metal produced with the oxide powders were evaluated using ferritoscope, optical microscopy, and Vickers microhardness test. Under the same welding parameters, the penetration capability of TIG welding with TiO2 and SiO2 fluxes was approximately 240% and 292%, respectively. A plasma column made with SiO2 flux exhibited greater constriction than that made with TiO2 flux. In addition, an anode root made with SiO2 flux exhibited more condensation than that made with TiO2 flux. Results indicate that energy density of SiO2-flux assisted TIG welding is higher than that of TiO2-flux assisted TIG welding.

  11. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    PubMed Central

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g−1·h−1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  12. TiO2 Sub-microsphere Film as Scaffold Layer for Efficient Perovskite Solar Cells.

    PubMed

    Huang, Yang; Zhu, Jun; Ding, Yong; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan

    2016-03-01

    TiO2 sub-microspheres composed of anatase granular-like nanocrystallines with an average diameter ∼250 nm are synthesized using sol-gel method and employed as the scaffold layer for efficient mesocopic perovskite solar cells. Compared with mesoporous TiO2 films composed of ∼18 nm nanoparticles, the sub-microsphere films show superior light-trapping characteristics and significantly improve the light-harvesting capability of the solar cells. In addition, the charge-transport performance is also dramatically improved according to the transient photocurrent decay despite there being no significant difference in the perovskite layer surface morphology. As a result, an average power conversion efficiency of 15% with a highly uniform distribution is achieved for the solar cells with TiO2 sub-microsphere films, 12% higher than those with TiO2 nanoparticle films. The combination of light-harvesting capability and fast charge transfer make the TiO2 sub-microsphere film a good candidate as the scaffold layer for efficient perovskite solar cells.

  13. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A.

    2014-08-01

    In this work, Fe-doped TiO2 nanoparticles ranging from a 0.2 to 1 weight % were grown from the surface of graphene sheet templates containing -COOH functionalities using sol-gel chemistry in a green solvent, a mixture of water/ethanol. The assemblies were characterized by a variety of analytical techniques, with the coordination mechanism examined theoretically using the density functional theory (DFT). Scanning electron microscopy and transmission electron microscopy images showed excellent decoration of the Fe-doped TiO2 nanoparticles on the surface of the graphene sheets >5 nm in diameter. The surface area and optical properties of the Fe-doped photocatalysts were measured by BET, UV and PL spectrometry and compared to non-graphene and pure TiO2 analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO2 were also studied theoretically using the Vienna ab initio Simulation Package based on DFT. Our first-principles theoretical investigations validated the experimental findings, showing the strength in the physical and chemical adsorption between the graphene and Fe-doped TiO2. The resulting assemblies were tested for photodegradation under visible light using 17β-estradiol (E2) as a model compound, with all investigated catalysts showing significant enhancements in photocatalytic activity in the degradation of E2.

  14. Photocatalytic degradation of L-acid by TiO2 supported on the activated carbon.

    PubMed

    Wang, Yu-Ping; Wang, Lian-Jun; Peng, Pan-Ying

    2006-01-01

    TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be effectively suppressed by added polyethylene glycol (PEG) as a surface modifier. The average particle diameter of TiO2, specific surface area and absorbability of catalyst can be modified. Based on characteristics of the TiO2 photocatalyst with XRD, specific surface area, adsorption valves of methylene blue and the amount of TiO2 supported on the activated carbon, the photocatalytic degradation of L-acid was studied. The effect of the factors, such as pH of the solution, the initial concentration of L-acid on the photocatalytic degradation of L-acid, were studied also. It was found that when the pH of the solution is 1.95, the amount of photocatalyst is 0.5 g, the concentration of the L-acid solution is 1.34 x 10(-3) mol/L and the illumination time is 7 h, the photocatalytic degradation efficiency of L-acid can reach 89.88%. The catalyst was reused 6 times and its degradation efficiency hardly changed.

  15. Excited-state dynamics of size-dependent colloidal TiO2-Au nanocomposites

    NASA Astrophysics Data System (ADS)

    Karam, Tony E.; Khoury, Rami A.; Haber, Louis H.

    2016-03-01

    The ultrafast excited-state dynamics of size-dependent TiO2-Au nanocomposites synthesized by reducing gold nanoclusters to the surface of colloidal TiO2 nanoparticles are studied using pump-probe transient absorption spectroscopy with 400 nm excitation pulses. The results show that the relaxation processes of the plasmon depletion band, which are described by electron-phonon and phonon-phonon scattering lifetimes, are independent of the gold nanocluster shell size surrounding the TiO2 nanoparticle core. The dynamics corresponding to interfacial electron transfer between the gold nanoclusters and the TiO2 bandgap are observed to spectrally overlap with the gold interband transition signal, and the electron transfer lifetimes are shown to significantly decrease as the nanocluster shell size increases. Additionally, size-dependent periodic oscillations are observed and are attributed to acoustic phonons of a porous shell composed of aggregated gold nanoclusters around the TiO2 core, with frequencies that decrease and damping times that remain constant as the nanocluster shell size increases. These results are important for the development of improved catalytic nanomaterial applications.

  16. Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.

    PubMed

    Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained.

  17. Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.

    PubMed

    Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained. PMID:25550120

  18. TiO2 hierarchical nanostructures: Hydrothermal fabrication and application in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liang, Jia; Zhang, Gengmin; Yang, Jin; Sun, Wentao; Shi, Mingji

    2015-01-01

    Arrays of TiO2 hierarchical nanostructures that consisted of rutile nanorods and anatase branches were hydrothermally fabricated and employed as photoanodes in dye-sensitized solar cells (DSSCs). Each hierarchical nanostructure array was attained in two steps. First, a primary nanorod array was synthesized in aqueous solutions of hydrochloric acid (HCl) and tetrabutyl titanate (C16H36O4Ti); subsequently, secondary branches were grown on the nanorods in aqueous solutions of ammonium hexafluorotitanate ((NH4)2TiF6) and boric acid (H3BO3). The secondary anatase branches filled part of the space among the primary rutile nanorods and gave rise to a larger surface area. Light-harvesting capability of the DSSCs with TiO2 hierarchical nanostructures as photoanodes was appreciably improved because more dye molecules could be loaded on the photoanodes and more light could be scattered inside the DSSCs. Therefore, the conversion efficiencies of the DSSCs were doubled by replacing the photoanode of primary TiO2 nanorod array with the photoanodes of TiO2 hierarchical nanostructure arrays. Furthermore, in order to reach a compromise between the photoanode surface area and the inter-nanorod space volume, the growth time of the secondary TiO2 anatase branches was optimized.

  19. An innovative ultrasound, Fe(2+) and TiO(2) photoassisted process for bisphenol A mineralization.

    PubMed

    Torres-Palma, Ricardo A; Nieto, Jessica I; Combet, Evelyne; Pétrier, Christian; Pulgarin, Cesar

    2010-04-01

    This paper explores the degradation of a model pollutant, bisphenol A, by an advanced oxidation process that combines sonolysis, Fe(2+), and TiO(2) in a photoassisted process. Experiments were done under saturated oxygen conditions. The effect of different Fe(2+) (0.56 and 5.6 mg/L) and TiO(2) (10 and 50 mg/L) concentrations was investigated on both the elimination and mineralization of the pollutant. A pronounced synergistic effect that led to the complete and rapid elimination of dissolved organic carbon (DOC) was observed even at low catalyst loadings. In this system, almost a complete removal of DOC (93%) was observed after 4 h using 10 and 5.6 mg/L of TiO(2) and Fe(2+), respectively, whereas at the same time, only 5, 6, and 22% of DOC was removed by an individual process alone (TiO(2) photocatalysis, ultrasound, and photo-Fenton, respectively). In this system, ultrasound has the principal role of eliminating the initial substrate and providing hydrogen peroxide for the photocatalytic systems, while photo-Fenton and TiO(2) photocatalysis are mainly responsible for the transformation of the intermediates in CO(2) and H(2)O. The role of H(2)O(2) generated from the sonochemical process is also discussed. PMID:20106498

  20. Arsenic removal from water employing heterogeneous photocatalysis with TiO2 immobilized in PET bottles.

    PubMed

    Fostier, Anne Hélène; Pereira, Maria do Socorro Silva; Rath, Susanne; Guimarães, José Roberto

    2008-05-01

    Arsenic oxidation (As(III) to As(V)) and As(V) removal from water were assessed by using TiO2 immobilized in PET (polyethylene terephthalate) bottles in the presence of natural sunlight and iron salts. The effect of many parameters was sequentially studied: TiO2 concentration of the coating solution, Fe(II) concentration, pH, solar irradiation time; dissolved organic carbon concentration. The final conditions (TiO2 concentration of the coating solution: 10%; Fe(II): 7.0 mg l(-1); solar exposure time: 120 min) were applied to natural water samples spiked with 500 microg l(-1) As(III) in order to verify the influence of natural water matrix. After treatment, As(III) and total As concentrations were lower than the limit of quantitation (2 microg l(-1)) of the voltammetric method used, showing a removal over 99%, and giving evidence that As(III) was effectively oxidized to As(V). The results obtained demonstrated that TiO2 can be easily immobilized on a PET surface in order to perform As(III) oxidation in water and that this TiO2 immobilization, combined with coprecipitation of arsenic on Fe(III) hydroxides(oxides) could be an efficient way for inorganic arsenic removal from groundwaters.

  1. Structure and Formation Mechanism of Black TiO2 Nanoparticles.

    PubMed

    Tian, Mengkun; Mahjouri-Samani, Masoud; Eres, Gyula; Sachan, Ritesh; Yoon, Mina; Chisholm, Matthew F; Wang, Kai; Puretzky, Alexander A; Rouleau, Christopher M; Geohegan, David B; Duscher, Gerd

    2015-10-27

    The remarkable properties of black TiO2 are due to its disordered surface shell surrounding a crystalline core. However, the chemical composition and the atomic and electronic structure of the disordered shell and its relationship to the core remain poorly understood. Using advanced transmission electron microscopy methods, we show that the outermost layer of black TiO2 nanoparticles consists of a disordered Ti2O3 shell. The measurements show a transition region that connects the disordered Ti2O3 shell to the perfect rutile core consisting first of four to five monolayers of defective rutile, containing clearly visible Ti interstitial atoms, followed by an ordered reconstruction layer of Ti interstitial atoms. Our data suggest that this reconstructed layer presents a template on which the disordered Ti2O3 layers form by interstitial diffusion of Ti ions. In contrast to recent reports that attribute TiO2 band-gap narrowing to the synergistic action of oxygen vacancies and surface disorder of nonspecific origin, our results point to Ti2O3, which is a narrow-band-gap semiconductor. As a stoichiometric compound of the lower oxidation state Ti(3+) it is expected to be a more robust atomic structure than oxygen-deficient TiO2 for preserving and stabilizing Ti(3+) surface species that are the key to the enhanced photocatalytic activity of black TiO2.

  2. Low Frequency Ultrasonication of Degussa P25 TiO2 and Its Superior Photocatalytic Properties.

    PubMed

    Vijayarangamuthu, K; Han, EunJi; Jeon, Ki-Joon

    2016-05-01

    We report the simple and effective method for enhancing the photocatalytic properties of Degussa P25 TiO2 by low frequency ultrasonication. The improvement in the crystallinity of ultrasonicated TiO2 was confirmed by the X-ray diffraction and Raman spectroscopy studies. Further, the X-ray photoelectron spectroscopy was utilized to study the changes in chemical nature and band edge due to the effect of ultrasonication and H2O2 solvent. The transmission electron microscope (TEM) was used to analysis the surface distortion. The Moire fringes in TEM were examined to understand the partial transformation of amorphous to crystalline anatase structure and overlapping of rutile over anatase crystal. The photocatalytic results indicated improvement in the degradation of methylene blue dye. The degradation efficiency was estimated to be 86% for ultrasonicated TiO2, which is higher as compared to 40% of P25. The rate constant values revealed four times superior degradation property of ultrasonicated TiO2. The improvement in the photocatalytic efficiency was correlated to the formation of rutile/anatase TiO2 aggregation and its consequences on electron-hole recombination. PMID:27483763

  3. Solid-state, planar photoelectrocatalytic devices using a nanosized TiO2 layer.

    PubMed

    Shang, Jing; Xie, Shaodong; Zhu, Tong; Li, Jia

    2007-11-15

    Solid-state planar photoelectrocatalytic devices using a nanosized Ti02 layer have been fabricated and used in the photodegradation of gaseous formaldehyde (HCHO). It is discovered for the first time that in the photocatalytic degradation of HCHO over TiO2 film, besides a well-known process of exciton dissociation expressed as TiO2* --> e(-) + h+ (process A), there exists an HCHO-involved process of exciton dissociation expressed as TiO2 + HCHO* --> TiO2(-) + HCHO+ (process B); these two processes have comparable contributions to the electron photogeneration. A biased photocatalytic device is unable to photodegrade HCHO under the nitrogen condition, but under the air condition, a positive synergic effect of bias on the photodegradation of HCHO over the planar photoelectrocatalytic device has been observed, mainly attributed to it that the horizontal electric field can displace electrons generated via process B away from their counterparts, effectively suppressing hole-electron recombination on TiO2 surface and thereby leading to the enhanced formation of O2- species. The current research points out that the planar photoelectrocatalytic device can provide the in-depth investigations on the mechanisms of the photocatalytic degradation over nanosized semiconductor oxide films, and also have potential application in decomposing and mineralizing organic gas-phase pollutants. PMID:18075102

  4. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    NASA Astrophysics Data System (ADS)

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-10-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g-1·h-1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts.

  5. WO3/TiO2 nanotube photoanodes for solar water splitting with simultaneous wastewater treatment.

    SciTech Connect

    Reyes, Karla Rosa; Robinson, David B.

    2013-05-01

    Nanostructured WO3/TiO2 nanotubes with properties that enhance solar photoconversion reactions were developed, characterized and tested. The TiO2 nanotubes were prepared by anodization of Ti foil, and WO3 was electrodeposited on top of the nanotubes. SEM images show that these materials have the same ordered structure as TiO2 nanotubes, with an external nanostructured WO3 layer. Diffuse reflectance spectra showed an increase in the visible absorption relative to bare TiO2 nanotubes, and in the UV absorption relative to bare WO3 films. Incident simulated solar photon-to-current efficiency increased from 30% (for bare WO3) to 50% (for WO3/TiO2 composites). With the addition of diverse organic pollutants, the photocurrent densities exhibited more than a 5-fold increase. Chemical oxygen demand measurements showed the simultaneous photodegradation of organic pollutants. The results of this work indicate that the unique structure and composition of these composite materials enhance the charge carrier transport and optical properties compared with the parent materials.

  6. Equilibrium lithium transport between nanocrystalline phases in intercalated TiO(2) anatase.

    PubMed

    Wagemaker, M; Kentgens, A P M; Mulder, F M

    2002-07-25

    Microcrystalline TiO(2) with an anatase crystal structure is used as an anode material for lithium rechargeable batteries, and also as a material for electrochromic and solar-cell devices. When intercalated with lithium, as required for battery applications, TiO(2) anatase undergoes spontaneous phase separation into lithium-poor (Li(0.01)TiO(2)) and lithium-rich (Li(0.6)TiO(2)) domains on a scale of several tens of nanometres. During discharge, batteries need to maintain a constant electrical potential between their electrodes over a range of lithium concentrations. The two-phase equilibrium system in the electrodes provides such a plateau in potential, as only the relative phase fractions vary on charging (or discharging) of the lithium. Just as the equilibrium between a liquid and a vapour is maintained by a continuous exchange of particles between the two phases, a similar exchange is required to maintain equilibrium in the solid state. But the time and length scales over which this exchange takes place are unclear. Here we report the direct observation by solid-state nuclear magnetic resonance of the continuous lithium-ion exchange between the intermixed crystallographic phases of lithium-intercalated TiO(2). We find that, at room temperature, the continuous flux of lithium ions across the phase boundaries is as high as 1.2 x 10(20) s(-1) m(-2).

  7. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

    PubMed

    Li, Xin; Dai, Si-Min; Zhu, Pei; Deng, Lin-Long; Xie, Su-Yuan; Cui, Qian; Chen, Hong; Wang, Ning; Lin, Hong

    2016-08-24

    Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process. PMID:27480286

  8. Comparisons between TiO2- and SiO2-flux assisted TIG welding processes.

    PubMed

    Tseng, Kuang-Hung; Chen, Kuan-Lung

    2012-08-01

    This study investigates the effects of flux compounds on the weld shape, ferrite content, and hardness profile in the tungsten inert gas (TIG) welding of 6 mm-thick austenitic 316 L stainless steel plates, using TiO2 and SiO2 powders as the activated fluxes. The metallurgical characterizations of weld metal produced with the oxide powders were evaluated using ferritoscope, optical microscopy, and Vickers microhardness test. Under the same welding parameters, the penetration capability of TIG welding with TiO2 and SiO2 fluxes was approximately 240% and 292%, respectively. A plasma column made with SiO2 flux exhibited greater constriction than that made with TiO2 flux. In addition, an anode root made with SiO2 flux exhibited more condensation than that made with TiO2 flux. Results indicate that energy density of SiO2-flux assisted TIG welding is higher than that of TiO2-flux assisted TIG welding. PMID:22962749

  9. Ta2O5- and TiO2-based nanostructures made by atomic layer deposition.

    PubMed

    Kemell, Marianna; Härkönen, Emma; Pore, Viljami; Ritala, Mikko; Leskelä, Markku

    2010-01-22

    Nanotubular Ta(2)O(5)- and TiO(2)-based structures were prepared by atomic layer deposition of Ta(2)O(5) and TiO(2) thin films, conformally on pore walls of porous alumina membranes. Both self-supporting alumina membranes and Si-supported thin-film membranes were studied as templates. Long Ta(2)O(5) and TiO(2) nanotubes were prepared successfully with the self-supporting membranes. The TiO(2) nanotubes showed photocatalytic activity in methylene blue degradation under UV illumination. The Ta(2)O(5) and TiO(2) nanotubes were further modified by depositing Pt nanoparticles inside them. The Si-supported thin-film membranes were used as templates for the preparation of robust Ta(2)O(5)-coated Ni nanorod arrays on a Si substrate using electrodeposition, chemical etching and atomic layer deposition. In addition to photocatalysis, the nanostructures prepared in this work may find applications as other catalysts and as solid-state or electrochemical capacitors.

  10. Self-referenced luminescence thermometry with Sm(3+) doped TiO2 nanoparticles.

    PubMed

    Dramićanin, M D; Antić, Ž; Ćulubrk, S; Ahrenkiel, S P; Nedeljković, J M

    2014-12-01

    The performance of Sm(3+) doped TiO2 nanoparticles for luminescence temperature sensing was tested over a temperature range from room to 110 °C. The Sm(3+) ions were incorporated into TiO2 nanocrystals using hydrolytic sol-gel route. Microstructural characterization of the obtained material was performed using transmission electron microscopy and x-ray diffraction measurements. Luminescence emission spectra of Sm(3+) doped TiO2 nanoparticles consists of two distinct spectral regions: the high energy region associated with the trap emission of the TiO2 host, and the low energy region with well-resolved emission peaks of the Sm(3+) ions. The ratio between Sm(3+) emission and TiO2 trap emission shows strong temperature dependence, and is tested for temperature sensing. The relative sensor sensitivity was found to be higher than 1% °C(-1) over given temperature range with the maximum value of 10.54% °C(-1) at 57.5 °C. Lifetime data derived from the Sm(3+) emission decay revealed that time-resolved measurements provide comparable quality of temperature sensing as corresponding ratiometric measurements, with a maximum relative sensitivity of 10.14% °C(-1) at 66.5 °C.

  11. Searching for new TiO2 crystal phases with better photoactivity

    NASA Astrophysics Data System (ADS)

    Shang, Cheng; Zhao, Wei-Na; Liu, Zhi-Pan

    2015-04-01

    Using the recently developed stochastic surface walking global optimization method, this work explores the potential energy surface of TiO2 crystals aiming to search for likely phases with higher photocatalytic activity. Five new phases of TiO2 are identified and the lowest energy phase transition pathways connecting to the most abundant phases (rutile and anatase) are determined. Theory shows that a high-pressure phase, α-PbO2-like form (TiO2II) acts as the key intermediate in between rutile and anatase. The phase transition of anatase to rutile belongs to the diffusionless Martensitic phase transition, occurring through a set of habit planes, rutile(101)//TiO2II(001), and TiO2II(100)//anatase(112). With regard to the photocatalytic activity, three pure phases (#110, pyrite and fluorite) are found to possess the band gap narrower than rutile, but they are unstable at the low-pressure condition. Instead, a mixed anatase-TiO2II phase is found to have good stability and narrower band gap than both parent phases. Because of the phase separation, the mixed phase is also expected to improve the photocatalytic performance by reducing the probability of the electron-hole pair recombination.

  12. Fine and ultrafine TiO2 particles in aerosol in Kraków (Poland)

    NASA Astrophysics Data System (ADS)

    Wilczyńska-Michalik, Wanda; Rzeźnikiewicz, Kamil; Pietras, Bartłomiej; Michalik, Marek

    2014-12-01

    During single particle analysis of aerosol in Kraków (Poland) we noticed a new component, that is, aggregates of TiO2 particles. These aggregates are from 0.5 to 4 μm and are composed of individual particles whose size typically varies from between 100 and 350 nm. Smaller particles (below 100 nm) also occur. TiO2 particles are relatively abundant in the summer. The size distribution of the particles corresponds to "pigmentary" TiO2, which indicates that they could be derived from paints and building materials. TiO2 particles were not previously identified in aerosol samples in Kraków, and therefore this phenomenon is likely to be related to the common usage of new building materials and paints. A review of the literature suggests that TiO2 particles, especially within the nanosize range, could result in health and environmental impacts; however, evaluation of the actual threat is difficult.

  13. Environmental risk induced by TiO2 dispersions in waters and sediments: a case study.

    PubMed

    Lettino, Antonio; Belviso, Claudia; Cavalcante, Francesco; Fiore, Saverio

    2016-02-01

    A southern Italian area that is characterized by large outcrops of rocks that are rich in titanium oxide (TiO2) phases were investigated to determine the mineralogical risk induced by the natural dispersion of TiO2 minerals. Rock, sediment and surface water samples were collected to determine the physicochemical and mineralogical factors (i.e., size distribution, morphology and alteration) indicative of potential TiO2 toxicity. X-ray diffraction data suggested that titanium oxides were present as rutile and anatase. Scanning electron microscopy images showed elongated TiO2 morphologies; fibres were found as either isolated or embedded/enclosed in flake-like phyllosilicates. The concentration of fibres in stream water ranged from 1.7 to 4.6 million fibres per litre. The highest fibre amounts in the sediments were in the <8-µm fraction, while single fibres were primarily concentrated in the <2-µm fraction. The results indicate that titanium oxide minerals represent a natural source of environmental risk and that the geomineralogical characterization of rich TiO2 areas is indispensable for understanding their geoavailability, dispersion and distribution. PMID:25682128

  14. TiO2 Microboxes with Controlled Internal Porosity for High-Performance Lithium Storage.

    PubMed

    Gao, Xuehui; Li, Gaoran; Xu, Yangyang; Hong, Zhanglian; Liang, Chengdu; Lin, Zhan

    2015-11-23

    Titanium dioxide (TiO2) is considered a promising anode material for high-power lithium ion batteries (LIBs) because of its low cost, high thermal/chemical stability, and good safety performance without solid electrolyte interface formation. However, the poor electronic conductivity and low lithium ion diffusivity of TiO2 result in poor cyclability and lithium ion depletion at high current rates, which hinder them from practical applications. Herein we demonstrate that hierarchically structured TiO2 microboxes with controlled internal porosity can address the aforementioned problems for high-power, long-life LIB anodes. A self-templating method for the synthesis of mesoporous microboxes was developed through Na2 EDTA-assisted ion exchange of CaTiO3 microcubes. The resulting TiO2 nanorods were organized into microboxes that resemble the microcube precursors. This nanostructured TiO2 material has superior lithium storage properties with a capacity of 187 mAh g(-1) after 300 cycles at 1 C and good rate capabilities up to 20 C.

  15. Efficient Perovskite Solar Cells Depending on TiO2 Nanorod Arrays.

    PubMed

    Li, Xin; Dai, Si-Min; Zhu, Pei; Deng, Lin-Long; Xie, Su-Yuan; Cui, Qian; Chen, Hong; Wang, Ning; Lin, Hong

    2016-08-24

    Perovskite solar cells (PSCs) with TiO2 materials have attracted much attention due to their high photovoltaic performance. Aligned TiO2 nanorods have long been used for potential application in highly efficient perovskite solar cells, but the previously reported efficiencies of perovskite solar cells based on TiO2 nanorod arrays were underrated. Here we show a solvothermal method based on a modified ketone-HCl system with the addition of organic acids suitable for modulation of the TiO2 nanorod array films to fabricate highly efficient perovskite solar cells. Photovoltaic measurements indicated that efficient nanorod-structured perovskite solar cells can be achieved with the length of the nanorods as long as approximately 200 nm. A record efficiency of 18.22% under the reverse scan direction has been optimized by avoiding direct contact between the TiO2 nanorods and the hole transport materials, eliminating the organic residues on the nanorod surfaces using UV-ozone treatment and tuning the nanorod array morphologies through addition of different organic acids in the solvothermal process.

  16. Effects of calcination treatment on the morphology, crystallinity, and photoelectric properties of all-solid-state dye-sensitized solar cells assembled by TiO2 nanorod arrays.

    PubMed

    Sun, Xianmiao; Sun, Qiong; Li, Yang; Sui, Lina; Dong, Lifeng

    2013-11-14

    TiO2 has been extensively investigated due to its unique photoelectric properties. In this study, oriented single-crystal rutile TiO2 nanorod arrays were synthesized and then calcined at different temperatures in the atmosphere. The morphology and crystalline characterization indicated that the length of TiO2 nanorods increased rapidly and the nanorods became aggregated and fragile after calcination, yet the sintering treatment seemed to have almost no effect on the crystallinity. To obtain the all-solid-state, dye-sensitized solar cells (DSSCs), a newly reported solid inorganic semiconductor, CsSnI2.95F0.05, was employed as the electrolyte, and the Pt deposited on the conductive side of the fluorine-doped tin oxide (FTO) glass substrate was used as the counter-electrode. The effects of the calcination treatment on the photoelectric properties of the solar cells, including external quantum efficiency (EQE), open circuit voltage (V(OC)), short-circuit current (J(SC)), and photoelectric conversion efficiency (η), were investigated under the illumination of a solar simulator. As a result, all of the EQE, V(OC), J(SC), and η values of the cells first increased and then declined with the increase of calcination temperatures, and the highest η of 2.81% was obtained by the cell assembled with its TiO2 electrode sintered at 450 °C for 3 h, a value almost 2.5 times that of the non-sintered sample (1.1%).

  17. Modification of the photocatalytic activity of TiO2 by β-Cyclodextrin in decoloration of ethyl violet dye

    PubMed Central

    Velusamy, Ponnusamy; Pitchaimuthu, Sakthivel; Rajalakshmi, Subramanian; Kannan, Nagarathinam

    2012-01-01

    The photocatalytic decoloration of an organic dye, ethyl violet (EV), has been studied in the presence of TiO2 and the addition of β-Cyclodextrin (β-CD) with TiO2 (TiO2-β-CD) under UV-A light irradiation. The different operating parameters like initial concentration of dye, illumination time, pH and amount of catalyst used have also been investigated. The photocatalytic decoloration efficiency is more in the TiO2-β-CD/UV-A light system than TiO2/UV-A light system. The mineralization of EV has been confirmed by Chemical Oxygen Demand (COD) measurements. The complexation patterns have been confirmed with UV–Visible and FT-IR spectral data and the interaction between TiO2 and β-CD have been characterized by powder XRD analysis and UV–Visible diffuse reflectance spectroscopy. PMID:25685468

  18. Self-organized TiO2 nanorod arrays on glass substrate for self-cleaning antireflection coatings.

    PubMed

    Mu, Qinghui; Li, Yaogang; Wang, Hongzhi; Zhang, Qinghong

    2012-01-01

    Herein we report the direct fabrication of TiO(2) subwavelength structures with 1-dimensional TiO(2) nanorods on glass substrate through solvothermal process to form self-cleaning antireflection coatings. TiO(2) precursor solutions with different solvent constituents create TiO(2) nanorods with much different morphologies grown on glass substrates. Apiculate TiO(2) nanorods with vertical orientation are grown on the glass substrate which is solvothermally treated in the precursor solution containing ethylene glycol. This glass substrate exhibit the highest transmittance of 70-85% in the range of 520-800 nm and negligible absorption in visible light region (400-800 nm). Furthermore, the TiO(2) nanorod arrays show high hydrophobicity and photocatalytic degradation ability which offer the glass substrate self-cleaning properties for both hydrophilic and oily contaminants.

  19. Hydrofluoric Acid Controlled TiO2 Phase Transformation from Rutile to Anatase at Room Temperature and Their Photocatalytic Performance.

    PubMed

    Ge, Suxiang; Li, Dapeng; Jia, Gaoyang; Wang, Beibei; Yang, Zhen; Yang, Zongyang; Qiao, Hui; Zhang, Yange; Zheng, Zhi

    2015-09-01

    In this study, we first present rutile TiO2 superstructures could be successfully transformed into anatase TiO2 nanoparticles at room temperature by adjusting the amount of hydrofluoric acid (HF) used in aqueous solution. Photocatalytic experiments demonstrated that the as prepared anatase TiO2 exhibited better photocatalytic performance than that of rutile TiO2. We further studied the photocatalytic degradation of RhB on different TiO2 via active species trapping experiments and confirmed that the presence of surface F- on TiO2 was beneficial for the formation of *OH, which was thought to be mainly responsible for the enhancement of photocatalytic performance.

  20. Promotion effect of Pd on TiO2 for visible light photocatalytic degradation of gaseous formaldehyde.

    PubMed

    Wu, Ren-Jang; Liu, Yung-Shiuan; Lai, Hsiao-Fang; Wang, Jhe-Hao; Chavali, Murthy

    2014-09-01

    TiO2 and Pd doped TiO2 (Pd/TiO2) nanoparticles were prepared by sol gel method. Pd/TiO2 material was characterized by XRD, TEM, TPR, XPS and BET. From XRD data, the crystalline type of TiO2 is known to as Anatase type. TiO2 and Pd/TiO2 were in the order of 9-10 nm and 10-13 nm respectively. The photocatalytic activities of the TiO2 and Pd/TiO2 nanomaterials were evaluated and compared for the photodegradation of formaldehyde (HCHO). HCHO degradation on Pd/TiO2 catalyst, at 60 min, the degradation rate of gaseous HCHO is 95%. Using Pd/TiO2, the rate was faster than TiO2 or doped with other metals (Au/TiO2; Ag/TiO2; Pt/TiO2).

  1. A novel drug delivery of 5-fluorouracil device based on TiO2/ZnS nanotubes.

    PubMed

    Faria, Henrique Antonio Mendonça; de Queiroz, Alvaro Antonio Alencar

    2015-11-01

    The structural and electronic properties of titanium oxide nanotubes (TiO2) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO2 has typically been within ultraviolet spectrum. In this study, the surface modification of TiO2 nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO2 nanotubes used in this work were obtained by sol-gel template synthesis. The ZnS quantum dots were deposited onto TiO2 nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO2/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO2 nanotubes exhibited a high emission at 380nm (3.26eV), whereas TiO2/ZnS exhibited an emission at 410nm (3.02eV). The TiO2/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells-CHO) suggesting that TiO2/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO2/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO2/ZnS nanotubes are a promising candidate for anticancer drug delivery systems. PMID:26249588

  2. Cr, N-Codoped TiO2 Mesoporous Microspheres for Li-ion Rechargeable Batteries with Enhanced Electrochemical Performance

    SciTech Connect

    Bi, Zhonghe; Paranthaman, Mariappan Parans; Guo, Bingkun; Unocic, Raymond R; Meyer III, Harry M; Bridges, Craig A; Sun, Xiao-Guang; Dai, Sheng

    2014-01-01

    Cr,N-codoped TiO2 mesoporous microspheres synthesized using hydrothermal and subsequent nitridation treatment, exhibited higher solubility of nitrogen, and improved electrical conductivity than N-doped TiO2, as anode for Lithium-ion rechargeable batteries, which led to improving charge-discharge capacity at 0.1 C and twice higher rate capability compared to that of nitrogen-doped TiO2 mesoporous microsphere at 10 C

  3. Effect of sunlight irradiation on photocatalytic pyrene degradation in contaminated soils by micro-nano size TiO2.

    PubMed

    Chang Chien, S W; Chang, C H; Chen, S H; Wang, M C; Madhava Rao, M; Satya Veni, S

    2011-09-01

    The enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils by micro-nano size TiO(2) in the presence and absence of sunlight was investigated. The results showed that the synergistic effect of sunlight irradiation and TiO(2) was more efficient on pyrene degradation in quartz sand and red and alluvial soils than the corresponding reaction system without sunlight irradiation. In the presence of sunlight irradiation, the photooxidation (without TiO(2)) of pyrene was very pronounced in alluvial and red soils and especially in quartz sand. However, in the absence of sunlight irradiation, the catalytic pyrene degradation by TiO(2) and the photooxidation (without TiO(2)) of pyrene were almost nil. This implicates that ultra-violet (UV) wavelength range of sunlight plays an important role in TiO(2)-enhanced photocatalytic pyrene degradation and in photooxidation (without TiO(2)) of pyrene. The percentages of photocatalytic pyrene degradation by TiO(2) in quartz sand, alluvial and red soils under sunlight irradiation were 78.3, 23.4, and 31.8%, respectively, at 5h reaction period with a 5% (w/w) dose of the amended catalyst. The sequence of TiO(2)-enhanced catalytic pyrene degradation in quartz sand and alluvial and red soils was quartz sand>red soil>alluvial soil, due to different texture and total organic carbon (TOC) contents of the quartz sand and other two soils. The differential Fourier transform infrared (FT-IR) spectra of degraded pyrene in alluvial soil corroborate that TiO(2)-enhanced photocatalytic degradation rate of degraded pyrene was much greater than photooxidation (without TiO(2)) rate of degraded pyrene. Based on the data obtained, the importance for the application of TiO(2)-enhanced photocatalytic pyrene degradation and associated organic contaminants in contaminated soils was elucidated.

  4. A novel drug delivery of 5-fluorouracil device based on TiO2/ZnS nanotubes.

    PubMed

    Faria, Henrique Antonio Mendonça; de Queiroz, Alvaro Antonio Alencar

    2015-11-01

    The structural and electronic properties of titanium oxide nanotubes (TiO2) have attracted considerable attention for the development of therapeutic devices and imaging probes for nanomedicine. However, the fluorescence response of TiO2 has typically been within ultraviolet spectrum. In this study, the surface modification of TiO2 nanotubes with ZnS quantum dots was found to produce a red shift in the ultra violet emission band. The TiO2 nanotubes used in this work were obtained by sol-gel template synthesis. The ZnS quantum dots were deposited onto TiO2 nanotube surface by a micelle-template inducing reaction. The structure and morphology of the resulting hybrid TiO2/ZnS nanotubes were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. According to the results of fluorescence spectroscopy, pure TiO2 nanotubes exhibited a high emission at 380nm (3.26eV), whereas TiO2/ZnS exhibited an emission at 410nm (3.02eV). The TiO2/ZnS nanotubes demonstrated good bio-imaging ability on sycamore cultured plant cells. The biocompatibility against mammalian cells (Chinese Hamster Ovarian Cells-CHO) suggesting that TiO2/ZnS may also have suitable optical properties for use as biological markers in diagnostic medicine. The drug release characteristic of TiO2/ZnS nanotubes was explored using 5-fluorouracil (5-FU), an anticancer drug used in photodynamic therapy. The results show that the TiO2/ZnS nanotubes are a promising candidate for anticancer drug delivery systems.

  5. Low-temperature fabrication of brown TiO2 with enhanced photocatalytic activities under visible light.

    PubMed

    Wang, Mingzheng; Nie, Biao; Yee, Ka-Kit; Bian, Haidong; Lee, Chris; Lee, Hung Kay; Zheng, Bo; Lu, Jian; Luo, Linbao; Li, Yang Yang

    2016-02-18

    Here we report a facile one-step low-temperature solution-based method to treat native TiO2 with NaH. The NaH treatment effectively induces the Ti(iii) species and oxygen vacancies into the TiO2 host lattice, and enables the absorption edge of TiO2 to be conveniently adjusted from the UV region to the red end of the visible spectrum.

  6. Synthesis and photonic band calculations of NCP face-centered cubic photonic crystals of TiO2 hollow spheres.

    PubMed

    Zhu, Yong-zheng; Cao, Yan-ling; Li, Zhi-hui; Ding, Juan; Liu, Jun-song; Chi, Yuan-bin

    2007-02-01

    With the help of self-assembly, thermal sintering, selective etching techniques and sol-gel process, the non-close packed (ncp) face-centered cubic (fcc) photonic crystals of titanium dioxide (TiO2) hollow spheres connected by TiO2 cylindrical tubes have been fabricated using silica template. The photonic bandgap calculations indicate that the ncp structure of TiO2 hollow spheres was easier to open the pseudogaps than close packed system at the lowest energy.

  7. Enhanced retention of bacteria by TiO2 nanoparticles in saturated porous media

    NASA Astrophysics Data System (ADS)

    Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.

    2016-08-01

    The simultaneous transport of TiO2 nanoparticles and bacteria Pseudomonas aeruginosa in saturated porous media was investigated. Nanoparticle and bacterium size and surface charge were measured as a function of electrolyte concentration. Sand column breakthrough curves were obtained for single and combined suspensions, at four different ionic strengths. DLVO and classical filtration theories were employed to model the interactions between particles and between particles and sand grains. Attachment of TiO2 to the sand was explained by electrostatic forces and these nanoparticles acted as bonds between the bacteria and the sand, leading to retention. Presence of TiO2 significantly increased the retention of bacteria in the sand bed, but microorganisms were released when nanomaterial influx ceased. The inclusion of nanomaterials in saturated porous media may have implications for the design and operation of sand filters in water treatment.

  8. Enhanced photodegradation of methyl orange with TiO2 nanoparticles using a triboelectric nanogenerator

    NASA Astrophysics Data System (ADS)

    Su, Yuanjie; Yang, Ya; Zhang, Hulin; Xie, Yannan; Wu, Zhiming; Jiang, Yadong; Fukata, Naoki; Bando, Yoshio; Wang, Zhong Lin

    2013-07-01

    Methyl orange (MO) can be degraded by a photocatalytic process using TiO2 under UV irradiation. The photo-generated holes and electrons can migrate to the surface of TiO2 particles and serve as redox sources that react with adsorbed reactants, leading to the formation of superoxide radical anions, hydrogen peroxide and hydroxyl radicals involved in the oxidation of dye pollution. Here, we fabricated a polytetrafluoroethylene-Al based triboelectric nanogenerator (TENG) whose electric power output can be used for enhancing the photodegradation of MO with the presence of TiO2 nanoparticles, because the TENG generated electric field can effectively boost the separation and restrain the recombination of photo-generated electrons and holes. Due to the photoelectrical coupling, the degradation percentages of MO for 120 min with and without TENG assistance are 76% and 27%, respectively. The fabricated TENGs have potential applications in wastewater treatment, water splitting, and pollution degradation.

  9. Low crystallinity TiO2 film with inherent low oxygen vacancy for sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Tang, Xiao; Liu, Xiaoyan; Zhang, Ling; Xing, Yali; Tian, Yi

    2014-09-01

    Instead of perfect crystallization or surface defect-removing treatments, this study suggests an alternative route of oxygen vacancy reduction, i.e. amorphization, to improve the electron transport properties of TiO2 mesoporous films. In this paper, a low crystallinity TiO2 mesoporous film with inherent low content of oxygen vacancies is used as the photoanode of dye-sensitized solar cells (DSCs). Electrochemical impedance spectroscopy (EIS) analysis indicates the high electron diffusion coefficient and long electron life time of the low crystallinity TiO2 photoanode. An extraordinary high open photovoltage of 860 mV is achieved owing to the low oxygen vacancy. And also the charge recombination of the internal cell significantly decreases, thus enhances the utilization efficiency of dye, which has been characterized with the high ratio of short circuit photocurrent to dye-loading.

  10. Influence of supported gold particles on the surface reactions of diethylamine on TiO2

    NASA Astrophysics Data System (ADS)

    Sarmiento-Lopez, Adan G.; Berumen-España, Gerardo; Lopez-Serrano, Cesar; Fierro-Gonzalez, Juan C.

    2016-11-01

    The adsorption and reactions of diethylamine on the surfaces of TiO2 and TiO2-supported gold samples were investigated by infrared (IR) spectroscopy and mass spectrometry. IR spectra measured as the samples were treated in flowing diethylamine at room temperature indicate that the amine was preferentially adsorbed molecularly on surface Ti4 + sites. Thermal treatment of the samples with flowing diethylamine led to the formation of ethylene and acetonitrile as dehydrogenation products. The data show that the reactions occurred at lower temperatures in the presence of supported gold samples than on TiO2, and IR spectra recorded under reaction conditions show evidence of amine-derived surface species bonded to gold nanoparticles that could be regarded as reaction intermediates. The results indicate that the gold nanoparticles provide sites for subtraction and recombination of hydrogen atoms from the amine, ensuing its dehydrogenation.

  11. Vibrational spectra and the structure peculiarity of TiO2 different polycrystalline forms

    NASA Astrophysics Data System (ADS)

    Shimanovskaya, V. V.; Khalyavka, T. A.; Puchkovska, Galina A.; Bezrodna, T. V.; Strelko, V. V.; Veblaya, T. S.; Baran, J.; Ratajczak, H.

    2002-12-01

    Particularly pure samples of titanium dioxide with a different crystalline structure and a different construction of TiO2 polycrystaline particles which were produced by thermal hydrolysis of TiCl4 hydrochloric acid solutions, were studied by methods of IR and Raman spectroscopy. The assignment of IR and Raman spectral bands to vibrations of different symmetry types has been performed. In accordance with positions and half-width of Raman lattice vibrational band 'ν=143 cm-1'. The stoichiometric composition estimation of TiO2 different crystalline phases has been carried out according to data obtained about the position and half-width of the lattice Raman vibrational band. The intensity and frequency of IR bands in the region of 1250-900 cm-1 were shown to be sensitive to a type of TiO2 crystalline composition and to the physically adsorbed water content.

  12. New structural and electronic properties of (TiO2)10

    NASA Astrophysics Data System (ADS)

    Aguilera-Granja, F.; Vega, A.; Balbás, L. C.

    2016-06-01

    We present, based on state of the art density functional theoretic calculations, a new putative ground state (GS) for the cluster (TiO2)10, which results more than 1 eV lower in energy than all those previously reported in the literature. The geometric and electronic properties of this new cluster are discussed in detail and in comparison with the rest. We analyze the implications of the new GS in the context of recent experiments of reactivity regarding oxygen exchange with gaseous CO2 in TiO2 nanostructures, and also in connection with a recent interpretation of photoelectron spectroscopic measurements of the band gap of gas phase TiO 2- clusters.

  13. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.

    PubMed

    Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  14. Surface chemistry influences cancer killing effect of TiO2 nanoparticles.

    PubMed

    Thevenot, Paul; Cho, Jai; Wavhal, Dattatray; Timmons, Richard B; Tang, Liping

    2008-09-01

    Photocatalyzed titanium dioxide (TiO2) nanoparticles have been shown to eradicate cancer cells. However, the required in situ introduction of ultraviolet light limits the use of such a therapy in humans. In the present study the nonphotocatalytic anticancer effect of surface-functionalized TiO2 was examined. Nanoparticles bearing -OH, -NH(2), or -COOH surface groups were tested for their effect on in vitro survival of several cancer and control cell lines. The cells tested included B16F10 melanoma, Lewis lung carcinoma, JHU prostate cancer cells, and 3T3 fibroblasts. Cell viability was observed to depend on particle concentrations, cell types, and surface chemistry. Specifically, -NH(2) and -OH groups showed significantly higher toxicity than -COOH. Microscopic and spectrophotometric studies revealed nanoparticle-mediated cell membrane disruption leading to cell death. The results suggest that functionalized TiO2, and presumably other nanoparticles, can be surface-engineered for targeted cancer therapy.

  15. Optimum Thickness Conditions of TiO2 Nanotubes Layer for Efficient Electrochemical Luminescence Cells Application.

    PubMed

    Choi, Min-Ki; Sung, Youl-Moon; Park, Min-Woo

    2015-02-01

    We report a TiO2 nanotubes (NTs)-based Electrochemical luminescence (ECL) cell. The ECL cell was fabricated using the electrode of TiO2 NTs and Ru(II) complex (Ru(bpy)2+(3)) as a luminescence materials. The fabricated ECL cell is composed of F-doped SnO2 (FTO) glass/Ru(II)/TiO2 NTs/Ti plate. At a bias voltage of 3 V, the measured ECL efficiencies were 0 Im/W for cell without NTs, 0.03 Im/W for NTs-6.5 µm, 0.07 Im/W for NTs-8 µm and 0.1 Im/W for NTs-10 µm, respectively. The use of Ti02 NTs increases ECL intensities by about 2 times compared to the typical ECL cell without the use of TiO2 NTs.

  16. Comparison of photovoltaic performance of TiO2 nanoparticles based thin films via different routes

    NASA Astrophysics Data System (ADS)

    Ji, Yajun

    2015-11-01

    Well crystallized TiO2 nanoparticles were prepared by hydrothermal and sol-gel routes, respectively. The morphologies, structures, crystallinity and optical properties of resulted TiO2 nanoparticles-based thin films via the two methods were examined by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and reflectance spectra. In addition, comparison of photovoltaic performance of TiO2 nanoparticles-based thin films by the two methods was performed. It is found that the maximum energy conversion efficiency of 4.06% was achieved based on the obtained electrode via hydrothermal, which is much better than that of the sol-gels route. The uniform film structure with improved dye absorption capability, increased diffused reflectance property and relatively low charge recombination rates for injected electrons are believed to be responsible to the superior photoelectrochemical properties of dye-sensitized solar cells (DSSC) via hydrothermal route.

  17. Core-shell TiO2 microsphere with enhanced photocatalytic activity and improved lithium storage

    NASA Astrophysics Data System (ADS)

    Guo, Hong; Tian, Dongxue; Liu, Lixiang; Wang, Yapeng; Guo, Yuan; Yang, Xiangjun

    2013-05-01

    Inorganic hollow core-shell spheres have attracted considerable interest due to their singular properties and wide range of potential applications. Herein a novel facile generic strategy of combining template assisted and solvothermal alcoholysis is employed to prepare core-void-shell anatase TiO2 nanoparticle aggregates with an excellent photocatalytic activity, and enhanced lithium storage in large quantities. Amorphous carbon can be loaded on the TiO2 nanoparticles uniformly under a suitably formulated ethanol/water system in the solvothermal alcoholysis process, and the subsequent calcination results of the formation of core-shell-shell anatase TiO2 nanoparticle aggregates. The intrinsic core-void-shell nature as well as high porosity of the unique nanostructures contributes greatly to the superior photocatalytic activity and improved performance as anode materials for lithium ion batteries.

  18. Preparation and photocatalytic properties of TiO2/mica composite for acetaldehyde degradation

    NASA Astrophysics Data System (ADS)

    Ozawa, Masakuni; Matui, Hidetomo; Suzuki, Suguru

    2016-01-01

    TiO2/mica composite was prepared by mixing mica and acidic solution of hydrolyzed titanium tetraisopropoxide, and characterized by X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), and N2 adsorption measurement. The results of experiments showed that the material had a catalytic composite powder structure containing pillared fragments with TiO2 after calcination at 300-800 °C. The resulting TiO2/mica exhibited good thermal stability, as indicated by its porosity and surface area, and interlayer stability of powders after calcination at 800 °C. The photocatalytic performances of these porous mica/TiO2 composites were evaluated by gaseous acetaldehyde degradation. The superior photocatalyic property was demonstrated and the maximum removal efficiency was up to 99% within 90 min, and the reaction kinetics was discussed.

  19. The origin of the strong microwave absorption in black TiO2

    NASA Astrophysics Data System (ADS)

    Li, Kexue; Xu, Jilian; Yan, Xiaodong; Liu, Lei; Chen, Xiaobo; Luo, Yongshi; He, Jun; Shen, D. Z.

    2016-05-01

    In this study, the mechanism of the strong microwave absorption in black TiO2 nanoparticles has been investigated both experimentally and theoretically. In experiment, the amorphous TiO2 nanoparticles/paraffin wax composites show the reflection loss (RL) of -4.0 dB, which is much smaller compared with the RL of -49.0 dB in those core/shell structure ones. Theoretically, the calculation illustrates that the accumulated charge of 1013 cm-3 at the core/shell interface results in the plasmon resonance with the incident microwave frequency at 9.3 GHz and 27.0 GHz. The microwave absorption enhancement of the black TiO2 nanoparticles is proposed to originate from the synergy mechanism between their crystalline-cores and amorphous-shells, rather than the defects and impurities in amorphous phase.

  20. Pure single crystallographic form of TiO2 nanoparticles: Preparation and characterization

    NASA Astrophysics Data System (ADS)

    Bhatt, Piyush J.; Tomar, Laxmi J.; Desai, Rahul K.; Chakrabarty, Bishwajit S.

    2015-06-01

    TiO2 nanoparticles in three pure crystallographic forms (anatase, rutile and Brookite) have been prepared by hydrothermal and precipitation method. XRD analysis showed that the prepared nanoparticles using hydrothermal method for 2h and 24h were pure Brookite and pure anatase respectively. Pure rutile phase of TiO2 nanoparticles has been obtained by precipitation method. The average crystallite size for anatase, rutile and Brookite was found to be 14.71 nm, 12.88 nm and 5.27 nm respectively. This nano size of crystals has produced lattice strain in material, and this strain varies with size and structure. The UV-Visible absorption analysis showed that the energy gaps for anatase, rutile and Brookite are 3.32 eV, 2.45 eV and 2.60 eV respectively. Refractive index of all the samples has been changed compared to the bulk TiO2.

  1. Structural, electronic, and dynamical properties of Pca21-TiO2 by first principles

    NASA Astrophysics Data System (ADS)

    Abbasnejad, M.; Mohammadizadeh, M. R.; Maezono, R.

    2012-03-01

    First-principles calculations of the structural, electronic, and mechanical properties of the modified fluorite structure of TiO2 with Pca21 symmetry are obtained using the plane-wave pseudopotential density functional theory. The results indicate that Pca21-TiO2 is a semiconductor with an indirect band gap. The calculated static dielectric constants are larger than those of anatase and brookite, but they are much smaller than those of rutile. The calculated bulk modulus using the equation of state is in good agreement with that calculated from elastic constants. The calculated bulk modulus is in agreement with a recent theoretical and experimental report, which confirms that the experimentally claimed structure (cubic fluorite phase) can be Pca21-TiO2.

  2. Electrochemical Properties of Rutile TiO2 Nanorod Array in Lithium Hydroxide Solution

    NASA Astrophysics Data System (ADS)

    Yu, Yan; Sun, Dan; Wang, Haibo; Wang, Haiyan

    2016-10-01

    In this paper, rutile TiO2 nanorod arrays are fabricated by a template-free method and proposed as a promising anode for aqueous Li-ion battery. The as-prepared TiO2 nanorod arrays exhibited reversible Li-ion insertion/extraction ability in aqueous LiOH electrolyte. Moreover, galvanostatic charge/discharge test results demonstrated that the reversible capacity of TiO2 nanorods could reach about 39.7 mC cm-2, and 93.8 % of initial capacity was maintained after 600 cycles at a current density of 1 mA cm-2 (=240 C rate), indicating excellent cycling stability and rate capability.

  3. PAMAM-grafted TiO2 nanotubes as novel versatile materials for drug delivery applications.

    PubMed

    Torres, Cecilia C; Campos, Cristian H; Diáz, Carola; Jiménez, Verónica A; Vidal, Felipe; Guzmán, Leonardo; Alderete, Joel B

    2016-08-01

    PAMAM-grafted TiO2 nanotubes (PAMAM-TiO2NT) have been synthesized and evaluated as new drug nanocarriers, using curcumin (CUR), methotrexate (MTX), and silibinin (SIL) as model therapeutic compounds. TiO2NT were surface-modified using a silane coupling agent and subsequently conjugated with PAMAM dendrimer of the third generation. The characterization of PAMAM-TiO2NT nanomaterials was performed by FTIR, TEM, N2 adsorption-desorption isotherms, XRD, and TGA techniques, which accounted for a 2.6wt.% of PAMAM grafting in the prepared materials. The drug loading capacity, drug release properties, and cytotoxicity of PAMAM-TiO2NT showed a significant improvement compared to pristine TiO2NT, thus revealing the promising properties of these new materials for drug delivery purposes. PMID:27157739

  4. Photoresponsive polypyrrole- TiO 2 nanoparticles film fabricated by a novel surface initiated polymerization

    NASA Astrophysics Data System (ADS)

    Wang, Jiao; Ni, Xiuyuan

    2008-05-01

    A Photosensitized electrode was fabricated through a novel polymerization of pyrrole initiated by TiO 2 nanoparticles under UV irradiation. Conjugated polypyrrole (PPy) continuously grows on the surface of the TiO 2 film, resulting in fully covered film with the stably-bound PPy layer. The film structures were analysed using Raman and X-ray photoelectron spectroscopy (XPS). It was found that the film electrode exhibits improved photoresponse including the flat band potential, photocurrent and separation of charges. The lowest unoccupied molecular orbital (LUMO) level of the PPy is higher in energy than the LUMO of PPy in electrodeposited electrodes, providing a stronger driving force for the electron injection into the TiO 2.

  5. 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

  6. TiO2 nanosized powders controlling by ultrasound sol-gel reaction.

    PubMed

    Latt, Kyaing Kyaing; Kobayashi, Takaomi

    2008-04-01

    We studied that anatase-TiO2 powders prepared from sol-gel process of titanium tetra-isopropoxide (TTIP) were developed under ultrasonic irradiation with different frequency of 28, 45 and 100 kHz. The irradiated ultrasound (US) was controlled by using semi-cylindrical reflection plate that was placed onto the vicinity of reaction vessel. The focused US influenced the reduction of particles size and increased the surface area of resultant nanosized TiO2 powders. We also examined photodegradation of rhodamine 640 dye (Rh-640) solution by the resultant TiO2 under UV light exposure. It was observed that low frequency for TiO2 photocatalyst preparation and low calcination temperature were more affected onto the photodegradation of the dye. PMID:17904404

  7. On the Effect of TiO2 Nanoparticles on the Crystallization of PEO

    NASA Astrophysics Data System (ADS)

    Saldana, Jesus Eduardo; Chipara, Alin Cristian; Castillo, Alejandro; Hinthorne, James; Ibrahim, Elamin; Chipara, Mircea

    2014-03-01

    Nanocomposite consisting of various amounts of TiO2 nanoparticles dispersed within polyethylene oxide (PEO) have been prepared by melt mixing. The thermal properties of these nanocomposites have been investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). TGA data revealed a weak increase of the thermal stability of the PEO matrix upon the loading with nanoparticles. The crystalline structure of PEO and TiO2 has been confirmed by Wide Angle X-Ray Scattering and electron microscopy. Isothermal and non isothermal DSC was used to investigate the melting/crystallization process. Additional information regarding the nanofiller has been obtained via Raman and FTIR spectroscopy. The shift of the melting and crystallization temperature due to the loading with TiO2 nanoparticles is analyzed.

  8. Enhanced retention of bacteria by TiO2 nanoparticles in saturated porous media.

    PubMed

    Gentile, Guillermina J; Fidalgo de Cortalezzi, María M

    2016-08-01

    The simultaneous transport of TiO2 nanoparticles and bacteria Pseudomonas aeruginosa in saturated porous media was investigated. Nanoparticle and bacterium size and surface charge were measured as a function of electrolyte concentration. Sand column breakthrough curves were obtained for single and combined suspensions, at four different ionic strengths. DLVO and classical filtration theories were employed to model the interactions between particles and between particles and sand grains. Attachment of TiO2 to the sand was explained by electrostatic forces and these nanoparticles acted as bonds between the bacteria and the sand, leading to retention. Presence of TiO2 significantly increased the retention of bacteria in the sand bed, but microorganisms were released when nanomaterial influx ceased. The inclusion of nanomaterials in saturated porous media may have implications for the design and operation of sand filters in water treatment. PMID:27258326

  9. Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.

    PubMed

    Yang, Chang-Hu; Ma, Zhong-Quan

    2012-08-01

    TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples.

  10. Preparation of {0 1 0}-faceted anatase TiO2 nanocuboids from peroxotitanium complex solution

    NASA Astrophysics Data System (ADS)

    Miao, Yigao; Gao, Jiacheng

    2012-12-01

    {0 1 0}-faceted anatase TiO2 nanocuboids have been fabricated by hydrothermal route using peroxotitanium complex solution as precursor. The effects of reaction time, the amount of urea and temperature on the formation of {0 1 0}-faceted anatase TiO2 were characterized by XRD, FESEM and TEM. The growth mechanism of nanocuboids was proposed that the nanocuboids were formed by the transition from H2Ti2O5·H2O phase to anatase TiO2 in the basic condition. The photocatalytic performance of the prepared samples was tested in the degradation of Rhodamine B and the anatase nanocuboids exhibited enhanced photocatalytic activity compared with the standard P25 powders.

  11. [Photocatalytic degradation kinetics of diuron by TiO2 and simulated sunlight].

    PubMed

    Yang, Hai; Zeng, Jian; Li, Yuan; Yang, Li-Ping; Yi, Bing

    2013-08-01

    Photocatalytic degradation kinetics of diuron in aqueous solution was systematically investigated using TiO2 as the photocatalyst. The single-variable-at-a-time (SVAT) method and the central composite design (CCD) based on response surface methodology (RSM) were employed to study the individual and synergistic effects of several classical parameters on photocatalytic efficiencies. Three different parameters, namely TiO2 concentration, pH value and initial temperature of the model pollutant, were found to independently determine the degradation efficiencies. From the SVAT experiments, it could be concluded that neutral solutions were favorable for the degradation of diuron, and the degradation rate increased with the increasing temperature. Moreover, the results from CCD indicated that the optimum degradation conditions were as follows: TiO2 concentration at 2.98 g x L(-1), pH value at 7.78, and temperature at 40 degrees C.

  12. Photoconductive detection of hydrogen in ZnO and rutile TiO2

    NASA Astrophysics Data System (ADS)

    Lavrov, E. V.; Mchedlidze, T.; Herklotz, F.

    2016-08-01

    Hydrogen donors in ZnO and rutile TiO2 are probed by means of photoconductivity and IR absorption. It is shown that the O-H bonds giving rise to the local vibrational modes (LVMs) of interstitial hydrogen at 3611 and 3290 cm-1 in the case of ZnO and TiO2, respectively, also occur in the photoconductivity spectra as Fano resonances. The effects of isotope substitution, concentration, sample thickness, influence of other donors present in both oxides are considered. Based on the shape and frequency of these resonances, it is concluded that the apparent ionization energy of interstitial hydrogen in rutile TiO2 is less than 300 meV. By a direct comparison, we also demonstrate that photoconductive detection of LVMs of defects in thin semiconductor films is superior to the standard IR absorption.

  13. TiO2-coated nanostructures for dye photo-degradation in water

    PubMed Central

    2014-01-01

    The photocatalytic efficiency of a thin-film TiO2-coated nanostructured template is studied by dye degradation in water. The nanostructured template was synthesized by metal-assisted wet etching of Si and used as substrate for the deposition of a thin film of TiO2 (10 nm thick) by atomic layer deposition. A complete structural characterization was made by scanning and transmission electron microscopies. The significant photocatalytic performance was evaluated by the degradation of two dyes in water: methylene blue and methyl orange. The relevance of the reported results is discussed, opening the route toward the application of the synthesized nanostructured TiO2 for water purification. PMID:25246868

  14. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island

    PubMed Central

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  15. Characterization and photocatalytic activity of Zn 2+-TiO 2/AC composite photocatalyst

    NASA Astrophysics Data System (ADS)

    Lu, Xincheng; Jiang, Jianchun; Sun, Kang; Cui, Dandan

    2011-12-01

    Activated carbon (AC) supported Zn 2+-TiO 2 photocatalyst was prepared by sol-gel method. The prepared samples were characterized by X-ray diffraction, scanning electron micrograph, nitrogen absorption, diffuse reflectance UV/VIS and X-ray photoelectron spectroscopy. Using toluene as a pollution target, the photocatalytic activity of photocatalyst was evaluated. The results showed that prepared photocatalyst was obviously helpful for the removal of toluene in air. The photocatalytic degradation of toluene by Zn 2+-TiO 2/AC reached 100% for 40 min and remained 75% after 160 min, while degradation by TiO 2 was only 30%. It indicated that the photocatalytic activity of prepared photocatalyst was enhanced. It is due to Zn 2+-doping increased the oxidation and reduction of hole-electron pairs, which was the important factor in heterogeneous photocatalysis.

  16. Enhanced Photocatalytic Performance Using One Dimensional Ordered TiO2 Nanorods Modified by Graphene Oxide.

    PubMed

    Huang, Jinzhao; Fu, Ke; Yao, Nannan; Deng, Xiaolong; Ding, Meng; Shao, Minghui; Xu, Xijin; Wei, Mingzhi

    2016-02-01

    A new architecture of one dimensional ordered TiO2 nanorods modified by graphene oxide (GO) was assembled. The GO as the higher carrier mobility can reduce the recombination of carriers, which is more favourable for the methy orange (MO) degradation. Incorporating GO with the unblocked passageway for carrier transportation of the TiO2 nanorods can separate the transport pathway of electron and hole effectively. Furthermore, the large surface areas of TiO2 nanorods grown on the GO are beneficial to the enhancement of photocatalytic properties, and the reasonable band energy level can be obtained for the architecture, which is favorable for enhancing carrier separation and transportation. Finally, the higher transparency of the structure can enhance the light absorption. The photocatalyst grown on FTO substrates makes it easier to collect and recycle. PMID:27433607

  17. Fabrication of UV Photodetector on TiO2/Diamond Film.

    PubMed

    Liu, Zhangcheng; Li, Fengnan; Li, Shuoye; Hu, Chao; Wang, Wei; Wang, Fei; Lin, Fang; Wang, Hongxing

    2015-09-24

    The properties of ultraviolet (UV) photodetector fabricated on TiO2/diamond film were investigated. Single crystal diamond layer was grown on high-pressure-high-temperature Ib-type diamond substrate by microwave plasma chemical vapor deposition method, upon which TiO2 film was prepared directly using radio frequency magnetron sputtering technique in Ar and O2 mixing atmosphere. Tungsten was used as electrode material to fabricate metal-semiconductor-metal UV photodetector. The dark current is measured to be 1.12 pA at 30 V. The photo response of the device displays an obvious selectivity between UV and visible light, and the UV-to-visible rejection ratio can reach 2 orders of magnitude. Compared with that directly on diamond film, photodetector on TiO2/diamond film shows higher responsivity.

  18. Influence of Atomic Layer Deposition Temperatures on TiO2/n-Si MOS Capacitor

    SciTech Connect

    Wei, Daming; Hossain, T; Garces, N. Y.; Nepal, N.; Meyer III, Harry M; Kirkham, Melanie J; Eddy, C.R., Jr.; Edgar, J H

    2013-01-01

    This paper reports on the influence of temperature on the structure, composition, and electrical properties of TiO2 thin films deposited on n-type silicon (100) by atomic layer deposition (ALD). TiO2 layers around 20nm thick, deposited at temperatures ranging from 100 to 300 C, were studied. Samples deposited at 250 C and 200 C had the most uniform coverage as determined by atomic force microscopy. The average carbon concentration throughout the oxide layer and at the TiO2/Si interface was lowest at 200 C. Metal oxide semiconductor capacitors (MOSCAPs) were fabricated, and profiled by capacitance-voltage techniques. Negligible hysteresis was observed from a capacitance-voltage plot and the capacitance in the accumulation region was constant for the sample prepared at a 200 C ALD growth temperature. The interface trap density was on the order of 1013 eV-1cm-2 regardless of the deposition temperature.

  19. Stability of TiO2 Nanoparticles in Deionized Water with ZrP Nanoplatelets.

    PubMed

    Liu, Zhuowei; Chen, Ying; Mo, Songping; Cheng, Zhengdong; Li, Huawel

    2015-04-01

    The stability of nanofluid is an important property that needs to be researched. In our study, a novel method using Zirconium phosphate (ZrP) discotic colloid to disperse nanoparticles was proposed for improving stability. TiO2 nanofluid was prepared by dispersing TiO2 nanoparticles into exfoliated a-ZrP suspensions at different concentrations. Scanning electron microscopy and X-ray diffraction were used to characterize the shape, average size, and components of primary ZrP nanoplatelets. The absorbance of the suspensions was measured by a UV-VIS spectrophotometer. The results show that the stability first increased, and then decreased with increasing ZrP concentration at 1 wt.% TiO2. The effect was optimal at 2 wt.% ZrP. Thus, the hindrance of nanoplatelets in the aggregation and sedimentation of nanoparticles is the main reason for improving the stability of nanofluids. PMID:26353576

  20. TiO2 Nanotube Array Sensor for Detecting the SF6 Decomposition Product SO2

    PubMed Central

    Zhang, Xiaoxing; Zhang, Jinbin; Jia, Yichao; Xiao, Peng; Tang, Ju

    2012-01-01

    The detection of partial discharge through analysis of SF6 gas components in gas-insulated switchgear, is significant for the diagnosis and assessment of the operating state of power equipment. The present study proposes the use of a TiO2 nanotube array sensor for detecting the SF6 decomposition product SO2, and the application of the anodic oxidation method for the directional growth of highly ordered TiO2 nanotube arrays. The sensor response of 10–50 ppm SO2 gas is tested, and the sensitive response mechanism is discussed. The test results show that the TiO2 nanotube sensor array has good response to SO2 gas, and by ultraviolet radiation, the sensor can remove attached components very efficiently, shorten recovery time, reduce chemical poisoning, and prolong the life of the components. PMID:22737009