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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. Electronic properties of TiO2 doped with Sc, Y, La, Zr, Hf, V, Nb and Ta

    NASA Astrophysics Data System (ADS)

    Pan, J. W.; Li, C.; Zhao, Y. F.; Liu, R. X.; Gong, Y. Y.; Niu, L. Y.; Liu, X. J.; Chi, B. Q.

    2015-05-01

    The segregation of dopant inevitably affects the thermodynamic stability and electronic properties of transition metal (TM) doped TiO2 which were studied using first principles calculations. Here we show that the thermodynamic stability of doped systems is related with the doped position which is different for the considered TM dopants. The second phase could appear in V-doped TiO2 due to the Vsbnd Osbnd V bonding. The thermodynamic stability and electronic properties of the doped systems will be slightly infected by dopant concentration. Moreover, the band gaps are approximately proportional to the Mulliken population values of TMsbnd O bond.

  3. 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.

  4. 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.

  5. Optimization of antimicrobial and physical properties of alginate coating containing carvacrol and methyl cinnamate for strawberry application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Response surface methodology (RSM) was used to evaluate the effect of different concentrations of carvacrol (0.25 – 0.5 % w/w) and methyl cinnamate (0.5 - 2.5 % w/w), natural active compounds, in alginate coating solutions to improve the antimicrobial and physical properties of the coating. Antimicr...

  6. Enhanced aggregation of alginate-coated iron oxide (hematite) nanoparticles in the presence of calcium, strontium, and barium cations.

    PubMed

    Chen, Kai Loon; Mylon, Steven E; Elimelech, Menachem

    2007-05-22

    Early-stage aggregation kinetics studies of alginate-coated hematite nanoparticles in solutions containing alkaline-earth metal cations revealed enhanced aggregation rates in the presence of Ca2+, Sr2+, and Ba2+, but not with Mg2+. Transmission electron microscopy (TEM) imaging of the aggregates provided evidence that alginate gel formation was essential for enhanced aggregation to occur. Dynamic light scattering (DLS) aggregation results clearly indicated that a much lower concentration of Ba2+ compared to Ca2+ and Sr2+ was required to achieve a similar degree of enhanced aggregation in each system. To elucidate the relationship between the alginate's affinities for divalent cations and the enhanced aggregation of the alginate-coated hematite nanoparticles, atomic force microscopy (AFM) was employed to probe the interaction forces between alginate-coated hematite surfaces under the solution chemistries used for the aggregation study. Maximum adhesion forces, maximum pull-off distances, and the work of adhesion were used as indicators to gauge the alginate's affinity for the divalent cations and the resulting attractive interactions between alginate-coated hematite nanoparticles. The results showed that alginate had higher affinity for Ba2+ than either Sr2+ or Ca2+. This same trend was consistent with the cation concentrations required for comparable enhanced aggregation kinetics, suggesting that the rate of alginate gel formation controls the enhanced aggregation kinetics. An aggregation mechanism incorporating the gelation of alginate is proposed to explain the accelerated aggregate growth in the presence of Ca2+, Sr2+, and Ba2+. PMID:17469860

  7. Bioactive alginate coatings to control Listeria monocytogenes on cold-smoked salmon slices and fillets.

    PubMed

    Neetoo, Hudaa; Ye, Mu; Chen, Haiqiang

    2010-01-01

    The relatively high incidence of Listeria monocytogenes in cold smoked salmon (CSS) is of concern as CSS is a ready-to-eat product. No post-processing measures are currently available to control this pathogen in CSS. The objective of this study was to develop an effective antimicrobial edible coating containing organic salts to control the growth of L. monocytogenes in CSS slices and fillets. An in-house made formulation consisting of sodium lactate (SL, 0-2.4%) and sodium diacetate (SD, 0-0.25%) as well as 2.5% OptiForm (a commercial formulation of SL and SD) were incorporated into five edible coatings: alginate, kappa-carrageenan, pectin, gelatin or starch. The coatings were applied onto the surface of CSS slices inoculated with L. monocytogenes to an inoculum level of 500 CFU/cm(2) ( approximately 3 log CFU/g) and stored at room temperature (22 degrees C) for 6 days. Alginate coating was found to be the most effective carrier for the various antimicrobial treatments in inhibiting the growth of L. monocytogenes. In the second phase of the study, CSS slices and fillets inoculated with the pathogen at a level of 500 CFU/cm(2) were coated with alginate incorporating the in-house made and the commercial (OptiForm) SL/SD based formulations and stored for 30 days at 4 degrees C. When cold-smoked salmon slices and fillets were stored at 4 degrees C, alginate coatings supplemented with 2.4%SL/0.25%SD and the commercial product OptiForm significantly delayed the growth of L. monocytogenes during the 30-day storage with final counts reaching 4.1 and 3.3 log CFU/g (slices) and 4.4 and 3.8 log CFU/g (fillets), respectively, while the counts in their untreated counterparts were significantly higher (P<0.05) reaching 7.3 and 6.8 log CFU/g for slices and fillets, respectively. Therefore, this study demonstrates the effectiveness of using an alginate-based coating containing lactate and diacetate to control the growth of L. monocytogenes to enhance the microbiological safety of

  8. 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

  9. Synthesis of TiO2/functionalized graphene sheets (FGSs) nanocomposites in super critical CO2

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chen, Bo; Charpentier, Paul A.

    2010-06-01

    Highly ordered TiO2 nanowire arrays were prepared on the surface of Functionalized Graphene sheets (FGSs) by solgel method using titanium isopropoxide monomer with acetic acid as the polycondensation agent in the green solvent, supercritical carbon dioxide (sc-CO2). Morphology of synthesized materials was studied by SEM and TEM. Optical properties of the nanocomposites studied by UV spectroscopy which showed high absorption in visible area as well as reduction in their band gap compared to TiO2. By high resolution XPS, chelating bidentate structure of TiO2 with carboxylic group on the surface of graphene sheets can be confirmed. Improvement in the optical properties of the synthesized composites compared to TiO2 alone was confirmed by photocurrent measurements.

  10. Polycrystalline TiO2 (B) Nanosheet Films Deposited via Langmuir-Blodgett Method

    NASA Astrophysics Data System (ADS)

    Biedermann, Laura; Kotula, Paul; Beechem, Thomas; Dylla, Anthony; Stevenson, Keith; Chan, Calvin

    2014-03-01

    As an energy storage material, TiO2 offers higher Li+ capacities and smaller volume changes with lithiation than graphite electrodes. In particular, the bronze phase, TiO2(B) has a higher lithiation capacity (1.0 Li+/Ti) and faster lithiation kinetics due to its larger lattice parameters than other TiO2 polymorphs. Direct observation of lithiation will require TiO2(B) monolayers, such as those prepared via Langmuir-Blodgett deposition of the nanosheets (NS). Optical microscopy of the TiO2(B)-NS Langmuir monolayer at the air/water interface shows that these nanosheets assemble into large (>1 mm) islands. These elastic TiO2(B)-NS monolayers are deposited on diverse substrates for further characterization. Electron diffraction in both transmission electron microscopy (TEM) and low-energy electron microscopy (LEEM) of these films confirm that their polycrystalline structure is predominately composed of TiO2(B) nanocrystals, ~10s nm across. Discrimination of monolayer and bilayer TiO2(B) is evident in LEEM. Thermal stability of these nanosheets is investigated via in-situ TEM and ex-situ Raman spectroscopy. This monolayer TiO2(B) deposition will allow future observations of lithiation and phase changes. Sandia is managed by Sandia Corp., a subsidiary Lockheed Martin, for the U.S. DOE NNSA (DE-AC04-94AL85000). Work was supported by an U.S. DOE BES EFRC (DE-SC0001091).

  11. 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

  12. 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.

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

    PubMed

    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

  14. 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

  15. 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

  16. Diameter-sensitive biocompatibility of anodic TiO2 nanotubes treated with supercritical CO2 fluid

    PubMed Central

    2013-01-01

    This work reports on the diameter-sensitive biocompatibility of anodic TiO2 nanotubes with different nanotube diameters grown by a self-ordering process and subsequently treated with supercritical CO2 (ScCO2) fluid. We find that highly hydrophilic as-grown TiO2 nanotubes become hydrophobic after the ScCO2 treatment but can effectively recover their surface wettability under UV light irradiation as a result of photo-oxidation of C-H functional groups formed on the nanotube surface. It is demonstrated that human fibroblast cells show more obvious diameter-specific behavior on the ScCO2-treated TiO2 nanotubes than on the as-grown ones in the range of diameters of 15 to 100 nm. This result can be attributed to the removal of disordered Ti(OH)4 precipitates from the nanotube surface by the ScCO2 fluid, thus resulting in purer nanotube topography and stronger diameter dependence of cell activity. Furthermore, for the smallest diameter of 15 nm, ScCO2-treated TiO2 nanotubes reveal higher biocompatibility than the as-grown sample. PMID:23547743

  17. Porous TiO2 Assembled from Monodispersed Nanoparticles.

    PubMed

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

    2016-12-01

    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. PMID:27000026

  18. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  19. Formation mechanism of TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Yao, B. D.; Chan, Y. F.; Zhang, X. Y.; Zhang, W. F.; Yang, Z. Y.; Wang, N.

    2003-01-01

    Transmission electron microscopic observation showed that TiO2 nanotubes synthesized via a simple hydrothermal chemical process formed a crystalline structure with open-ended and multiwall morphologies. Unlike multiwalled carbon nanotubes, the TiO2 nanotube walls were not seamless. During alkali treatment, crystalline TiO2 raw material underwent delamination in the alkali solution to produce single-layer TiO2 sheets. TiO2 nanotubes were formed by rolling up the single-layer TiO2 sheets with a rolling-up vector of [001] and attracting other sheets to surround the tubes.

  20. Instability of hydrogenated TiO2.

    PubMed

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

    2015-11-19

    Hydrogenated TiO2 (H-TiO2) is touted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using nuclear reaction analysis (NRA), Rutherford backscattering spectrometry, ultraviolet photoelectron spectroscopy, and X-ray photoelectron spectroscopy. 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 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 at low temperatures, as well as its interfacial activity toward reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. PMID:26545303

  1. 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.

  2. 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.

  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. Double-layer coating of SrCO3/TiO2 on nanoporous TiO2 for efficient dye-sensitized solar cells.

    PubMed

    Wang, Shutao; Zhang, Xi; Zhou, Gang; Wang, Zhong-Sheng

    2012-01-14

    Surface modification plays a crucial role in improving the efficiency of dye-sensitized solar cells (DSSCs), but the reported surface treatments are in general superior to the untreated TiO(2) but inferior to the typical TiCl(4)-treated TiO(2) in terms of solar cell performance. This work demonstrates a two-step treatment of the nanoporous titania surface with strontium acetate [Sr(OAc)(2)] and TiCl(4) in order, each step followed by sintering. An electronically insulating layer of SrCO(3) is formed on the TiO(2) surface via the Sr(OAc)(2) treatment and then a fresh TiO(2) layer is deposited on top of the SrCO(3) layer via the TiCl(4) treatment, corresponding to a double layer of Sr(OAc)(2)/TiO(2) coated on the TiO(2) surface. As compared to the typical TiCl(4)-treated DSSC, the Sr(OAc)(2)-TiCl(4) treated DSSC improves short-circuit photocurrent (J(sc)) by 17%, open-circuit photovoltage (V(oc)) by 2%, and power conversion efficiency by 20%. These results indicate that the Sr(OAc)(2)-TiCl(4) treatment is better than the often used TiCl(4) treatment for fabrication of efficient DSSCs. Charge density at open circuit and controlled intensity modulated photocurrent/photovoltage spectroscopy reveal that the two electrodes show almost same conduction band level but different electron diffusion coefficient and charge recombination rate constant. Owing to the blocking effect of the SrCO(3) layer on electron recombination with I(3)(-) ions, the charge recombination rate constant of the Sr(OAc)(2)-TiCl(4) treated DSSC is half that of the TiCl(4)-treated DSSC, accounting well for the difference of their V(oc). The improved J(sc) is also attributed to the middle SrCO(3) layer, which increases dye adsorption and may improve charge separation efficiency due to the blocking effect of SrCO(3) on charge recombination. PMID:22108906

  5. Photoinduced interaction between riboflavin and TiO 2 colloid

    NASA Astrophysics Data System (ADS)

    Kathiravan, A.; Renganathan, R.

    2008-12-01

    The adsorption of riboflavin on the surface of TiO 2 colloidal particles and the electron transfer process from its singlet excited state to the conduction band of TiO 2 were examined by absorption and fluorescence quenching measurements. The apparent association constants ( Kapp) were determined. The quenching mechanism is discussed involving electron transfer from riboflavin to TiO 2.

  6. 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.

  7. In-vivo delivery of therapeutic proteins by genetically-modified cells: comparison of organoids and human serum albumin alginate-coated beads.

    PubMed

    Shinya, E; Dervillez, X; Edwards-Lévy, F; Duret, V; Brisson, E; Ylisastigui, L; Lévy, M C; Cohen, J H; Klatzmann, D

    1999-12-01

    We have designed a self-assembling multimeric soluble CD4 molecule by inserting the C-terminal fragment of the alpha chain of human C4-binding protein (C4bp alpha) at the C-terminal end of human soluble CD4 genes. This CD4-C4bp alpha fusion protein (sMulti-CD4) and two other reference molecules, a fusion protein of human serum albumin (HSA) and the first two domains of CD4 (HSA-CD4) and monomeric soluble CD4 (sMono-CD4), were delivered in vivo by genetically modified 293 cells. These cells were implanted in mice as organoids and also encapsulated in HSA alginate-coated beads. sMulti-CD4 showed an apparent molecular weight of about 300-350 kDa, in accordance with a possible heptamer formula. sMulti-CD4 produced either in cell culture or in vivo in mice appeared to be a better invitro inhibitor of HIV infection than sMono-CD4. Plasma levels of sMulti-CD4, HSA-CD4, and sMono-CD4 reached approximately 2,300, 2,700, and 170 ng/mL, respectively, 13 weeks after in-vivo organoid implantation, which had formed tumours at that time. This suggests that the plasma half-life of sMulti-CD4 is much longer than that of sMono-CD4. The 293 xenogeneic cells encapsulated in HSA alginate-coated beads remained alive and kept secreting sMono-CD4 or HSA-CD4 continuously at significant levels for 18 weeks in nude mice, without tumour formation. When implanted in immunocompetent Balb/c mice, they were rejected two to three weeks after implantation. In contrast, encapsulated BL4 hybridoma cells remained alive and kept secreting BL4 anti-CD4 mAb for at least four weeks in Balb/c mice. These results suggest the clinical potential of the C4bp-multimerizing system, which could improve both the biological activity and the poor in-vivo pharmacokinetic performance of a monomeric functional protein like soluble CD4. These data also show that a systemic delivery of therapeutic proteins, including immunoglobulins, can be obtained by the in-vivo implantation of engineered allogeneic cells encapsulated

  8. 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.

  9. 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.

  10. Fine designing 3-dimensional ZnO nanowalls with TiO2 nanoparticles for DSSC application

    NASA Astrophysics Data System (ADS)

    Polkoo, Sajad Saghaye; Saievar-Iranizad, Esmaiel; Bayatloo, Elham

    2015-06-01

    In this research, we report a low-cost low-temperature hydrothermal technique for covering 3-dimensional (3-D) electrodeposited ZnO nanowall with thin layer of aggregated TiO2 nanoparticles on FTO substrate for dye-sensitized solar cell application, in a way that morphology and crystal structure of ZnO nanowalls were preserved. Comparing photovoltaic characteristics of devices with and without TiO2-coating layer, it was revealed that the 3-D ZnO/TiO2-nanostructured photoanode resulted in a 35 % cell performance improved mostly because of enhancement of short-circuit current density ( J sc) and open-circuit voltage ( V oc). The XRD pattern showed that 3-D ZnO nanowalls and TiO2 compose of wurtzite and anatase phases, respectively.

  11. Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lee, Sun Hong; Chae, Sang Youn; Hwang, Yun Jeong; Koo, Kee-Kahb; Joo, Oh-Shim

    2013-09-01

    Dye-sensitized solar cells (DSSCs) were fabricated using TiO2 nanoparticles (NPs), TiO2 nanotube arrays (NTAs), and surface-modified NTAs with a TiCl4 treatment. The photovoltaic efficiencies of the DSSCs using TiO2 NP, NTA, and TiCl4-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl4-treated TiO2 NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge-transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO2 NTAs contributes to the smaller charge-transfer resistance, resulting in a higher short circuit current ( J sc), even at lower dye adsorption. Furthermore, the TiCl4-treated NTAs showed even smaller charge-transfer resistance, resulting in the highest J sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl4-treated TiO2 electrodes.

  12. 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

  13. Biocidal effects of photocatalytic semiconductor TiO2.

    PubMed

    Rajagopal, G; Maruthamuthu, S; Mohanan, S; Palaniswamy, N

    2006-08-15

    Photocatalytic action of the commercial TiO(2) was the subject of study on the destruction of the microbes within the biofilms. The TiO(2) powder was characterized by X-ray diffraction (XRD) for identifying its type and the particle size was determined. The biofilm was allowed to form over TiO(2) coatings over glass slides irradiated with polychromatic light for different time durations and distances. It indicates that a five-fold decrease in bacterial count due to the formation of H(2)O(2) at TiO(2)/biofilm interface. The formation of H(2)O(2) at the TiO(2)/biofilm interface is estimated and it does not destroy the entire bacterial population within the biofilm. Bacterial killing effect is supported by FT-IR analysis. PMID:16870404

  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 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.

  15. 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.

  16. Fabrication of TiO2 Thick Film for Photocatalyst from Commercial TiO2 Powder

    NASA Astrophysics Data System (ADS)

    Asteti, S. Fuji; Syarif, D. Gustaman

    2008-03-01

    Photocatalytic activity of TiO2 thick film ceramics made of commercial TiO2 powder has been studied. The TiO2 powder was nano sized one that was derived from dried TiO2 suspension. The TiO2 suspension was made by pouring some blended commercial TiO2 powder into some amount of water. The paste of TiO2 was made by mixing the nano sized TiO2 powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 °C and heated at different temperatures (400 °C and 500 °C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue.

  17. 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.

  18. 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.

  19. 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. PMID:27416515

  20. 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

  1. 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

  2. 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

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  5. 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...

  6. Preparation of SiO2/TiO2 and TiO2/TiO2 micropattern and their effects on platelet adhesion and endothelial cell regulation

    NASA Astrophysics Data System (ADS)

    Li, Jing-an; Yang, Ping; Zhang, Kun; Ren, Hui-lan; Huang, Nan

    2013-07-01

    TiO2 films were applied on blood contact biomaterials for its excellent biocompatibility. The topological structure of the biomaterial surfaces have a significant impact on cell adhesion, spreading and proliferation. Thus, it is anticipated that the combination of TiO2 film deposition and surface micro-patterning will provide a potential application for cardiovascular implants materials. In this work, TiO2/TiO2 and SiO2/TiO2 micro-groove/ridge stripes on Si (100) were prepared by photolithography, wet etching and unbalanced magnetron sputtering (UBMS). Their surface morphology, chemical composition and wettability were investigated. The crystal structure of TiO2 films was characterised by X-ray diffraction (XRD). Platelet adhesion on the SiO2/TiO2 and TiO2/TiO2 surfaces was tested, and the morphology and behaviour of endothelial cells cultured on the micropatterned surfaces were observed. It was proved that the SiO2/TiO2 pattern could reduce platelet adhesion and aggregation compared with TiO2/TiO2 pattern, endothelial cells grew along the micro-stripes and their behaviour could be effectively regulated by micropatterned surface. So, it is suggested that the micropatterned SiO2/TiO2 surface can contribute more bio-compatible function of regulating and coordinating the behaviour of endothelial cells and platelets.

  7. 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.

  8. 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.

  9. TiO2 Nanoparticles Induced Hippocampal Neuroinflammation in Mice

    PubMed Central

    Ze, Xiao; Yu, Xiaohong; Pan, Xiaoyu; Lin, Anan; Zhao, Yue; Zhang, Chi; Zhou, Qiuping; Wang, Ling; Hong, Fashui

    2014-01-01

    Titanium dioxide nanoparticles (TiO2 NPs) have been used in various medical and industrial areas. However, the impacts of these nanoparticles on neuroinflammation in the brain are poorly understood. In this study, mice were exposed to 2.5, 5, or 10 mg/kg body weight TiO2 NPs for 90 consecutive days, and the TLRs/TNF-α/NF-κB signaling pathway associated with the hippocampal neuroinflammation was investigated. Our findings showed titanium accumulation in the hippocampus, neuroinflammation and impairment of spatial memory in mice following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly activated the expression of Toll-like receptors (TLR2, TLR4), tumor necrosis factor-α, nucleic IκB kinase, NF-κB-inducible kinase, nucleic factor–κB, NF-κB2(p52), RelA(p65), and significantly suppressed the expression of IκB and interleukin-2. These findings suggest that neuroinflammation may be involved in TiO2 NP-induced alterations of cytokine expression in mouse hippocampus. Therefore, more attention should be focused on the application of TiO2 NPs in the food industry and their long-term exposure effects, especially in the human central nervous system. PMID:24658543

  10. 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.

  11. 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.

  12. 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

  13. Low temperature fabrication of perovskite solar cells with TiO2 nanoparticle layers

    NASA Astrophysics Data System (ADS)

    Kanayama, Masato; Oku, Takeo; Suzuki, Atsushi; Yamada, Masahiro; Sakamoto, Hiroki; Minami, Satoshi; Kohno, Kazufumi

    2016-02-01

    TiO2/CH3NH3PbI3-based photovoltaic devices were fabricated by a spin-coating method using a mixture solution. TiO2 require high-temperature processing to achieve suitably high carrier mobility. TiO2 electron transport layers and TiO2 scaffold layers for the perovskite were fabricated from TiO2 nanoparticles with different grain sizes. The photovoltaic properties and microstructures of solar cells were characterized. Nanoparticle sizes of these TiO2 were 23 nm and 3 nm and the performance of solar cells was improved by combination of two TiO2 nanoparticles

  14. Elementary photocatalytic chemistry on TiO2 surfaces.

    PubMed

    Guo, Qing; Zhou, Chuanyao; Ma, Zhibo; Ren, Zefeng; Fan, Hongjun; Yang, Xueming

    2016-07-01

    Photocatalytic hydrogen production and pollutant degradation provided both great opportunities and challenges in the field of sustainable energy and environmental science. Over the past few decades, we have witnessed fast growing interest and efforts in developing new photocatalysts, improving catalytic efficiency and exploring the reaction mechanism at the atomic and molecular levels. Owing to its relatively high efficiency, nontoxicity, low cost and high stability, TiO2 becomes one of the most extensively investigated metal oxides in semiconductor photocatalysis. Fundamental studies on well characterized single crystals using ultrahigh vacuum based surface science techniques could provide key microscopic insight into the underlying mechanism of photocatalysis. In this review, we have summarized recent progress in the photocatalytic chemistry of hydrogen, water, oxygen, carbon monoxide, alcohols, aldehydes, ketones and carboxylic acids on TiO2 surfaces. We focused this review mainly on the rutile TiO2(110) surface, but some results on the rutile TiO2(011), anatase TiO2(101) and (001) surfaces are also discussed. These studies provided fundamental insights into surface photocatalysis as well as stimulated new investigations in this exciting field. At the end of this review, we have discussed how these studies can help us to develop new photocatalysis models. PMID:26335268

  15. Tailoring of electron diffusion through TiO2 nanowires

    NASA Astrophysics Data System (ADS)

    Jose, R.; Yusoff, M. M.

    2012-11-01

    Charge transport through a random network of onedimensional TiO2 nanostructures such as nanorods, nanowires, and nanofibers developed by electrospinning technique has been studied in the presence of an electrolyte by electrochemical impedance spectroscopy and transient photocurrent measurements. The results have been compared with the charge transport parameters of random TiO2 nanoparticle (25 nm) network. The charge transport was discussed under the framework of hopping transport. Continuous nanofibers had longer charge collecting times and short nanorods have enhanced scattering losses. The TiO2 films containing random network of nanowires of aspect ratio 10:1 can have an order of magnitude higher diffusion coefficient than other morphologies. Furthermore, charge transport through Nb-doped anatase TiO2 nanofibers was studied. It was observed that the Fermi level of TiO2 rise close to its conduction band and result in a band-edge type diffusion mechanism even at low bias voltages when 2 wt% Nb atoms replaces the Ti atoms in the anatase lattice. The Nb-doped anatase electrospun nanofibers showed high chemical capacitance, high effective diffusion coefficient, and lower transport resistance compared to the undoped samples and conventional nanoparticles.

  16. Hydrogen Impurity Defects in Rutile TiO2.

    PubMed

    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

  17. 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

  18. 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

  19. 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.

  20. Water - Based TiO2 Suspensions: A Raman Study

    NASA Astrophysics Data System (ADS)

    Rangel, Roberto; Chipara, Dorina; Yust, Brian; Padilla, Desiree; Chipara, Mircea

    The antibacterial features of TiO2 are under scrutiny due to the UV radiation, which contributes to the generation of reactive oxygen species, mainly in water environments. A study of TiO2 suspensions in water and broth is reported. TiO2 has a low solubility in water. TiO2 (anatase), with average diameter of 15 nm from Nanostructured & Amorphous Materials, Inc. has been added to the fluid (water, broth) and the mixture was stirred for 1-10 h, followed by a 10-60 minutes sonication. The suspension was left to sediment for 1 day before measurements. Quasistable suspensions of TiO2 in water and broth were investigated by Raman spectroscopy using a Renishaw InVia spectrometer operating at 532 and 785 nm. The spectra of the nanofiller have been simulated by a collection of Breit-Wigner Fano line shapes and the effect of the preparation conditions (stirring and sonication time) on the parameters of Raman lines are reported. The differences are explained by observing that the sonication destroys the agglomerates of anatase resulting in a better dispersion of nanoparticles and consequently a longer sedimentation time. Sample preparation/storage have been done both under dark and UV light conditions.

  1. 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

  2. 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.

  3. Semiconducting ferroelectric SbSI quantum dots in organically modified TiO2 matrix

    NASA Astrophysics Data System (ADS)

    Ye, Hui; Xu, Yuhuan; Mackenzie, John D.

    2000-05-01

    Semiconducting ferro electric antimony sulphoiodide (SbSI) microcrystallite doped organically modified TiO2 thin film and bulk solids are successfully fabricated by the sol- gel process. Ferro electric SbSI crystallites have some attractive properties, including high dielectric permittivity, high electro-optical coefficient and high photoconductivity. SbSI is also an intrinsic semiconductor with a relatively narrow energy gap. If the crystal size is near its Bohr radius and the microcrystallites are dispersed in a suitable matrix, a dramatic improvement of the third order non linearity will be achieved due to the quantum confinement effect. It is clear that the SbSI quantum dot composites are good candidates for electro-optical devices. Glycidoxypropyltrimetroxysilane modified TiO2 is used as the matrix and SbSI is synthesized in situ by using SbI3 SC9NH2)2 and H2S gas. The size is controlled by the heat-treatment conditions and is characterized by the XRD and HRTEM measurements. The optical absorption spectrum gives evidence of the quantum confinement effect. The third order susceptibility of the SbSI quantum dot is measured by the degenerate four wave mixing method.

  4. Photoinduced underwater superoleophobicity of TiO2 thin films.

    PubMed

    Sawai, Yusuke; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Fujii, Eiji; Miyake, Michihiro

    2013-06-11

    The photoinduced wettabilities of water, n-hexadecane, dodecane, and n-heptane on a flat TiO2 surface prepared by a sol-gel method-based coating were investigated. An amphiphilic surface produced by UV irradiation exhibited underwater superoleophobicity with an extremely high static oil contact angle (CA) of over 160°. The TiO2 surface almost completely repelled the oil droplet in water. A robust TiO2 surface with no fragile nanomicrostructure was fabricated on a Ti mesh with a pore size of approximately 150 μm. The fabricated mesh was found to be applicable as an oil/water separation filter. PMID:23701360

  5. Photoelectrical properties of TiO2-Si structures

    NASA Astrophysics Data System (ADS)

    Petrova, Yu S.; Zarubin, A. N.; Kalygina, V. M.; Zupiy, S. Yu

    2014-10-01

    The effect of thermal annealing at 500 and 750°C as well as treatment in oxygen plasma on electrical and photoelectrical characteristics of TiO2-Si structures were investigated. TiO2 films were deposited on n-Si substrates by magnetron sputtering. It was found that in the structures annealed at 500°C and treated in oxygen plasma a substantial part of the enhanced photocurrent was observed over a long time after removing of illumination with λ = 400 nm.

  6. 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.

  7. 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

  8. Polymer TiO2 solar cells: TiO2 interconnected network for improved cell performance

    NASA Astrophysics Data System (ADS)

    Oey, C. C.; Djurisic, A. B.; Wang, H.; Man, K. K. Y.; Chan, W. K.; Xie, M. H.; Leung, Y. H.; Pandey, A.; Nunzi, J.-M.; Chui, P. C.

    2006-02-01

    A titanium dioxide porous network structure was synthesized using a poly(styrene-block-polyethylene oxide) diblock copolymer template. The influence of the titanium precursor concentration and annealing temperature on the obtained morphology was studied. Heterojunction solar cells consisting of TiO2 porous network structure and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) were fabricated. The influence of the MEH-PPV layer thickness and device architecture on the solar cell performance was investigated. For an optimized device structure, a short-circuit current as high as 3.3 mA cm-2 is obtained under simulated solar illumination with an air mass AM 1.5 filter. The improved higher short-circuit current compared to other reports on MEH-PPV /TiO2 heterojunction cells can be attributed to improved morphology of the TiO2 layer.

  9. Photocatalytic degradation of methylene blue under UV light irradiation on prepared carbonaceous TiO2.

    PubMed

    Ramli, Zatil Amali Che; 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 m(2) 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

  10. 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

  11. TiO(2) nanotube arrays: intrinsic peroxidase mimetics.

    PubMed

    Zhang, Lingling; Han, Lei; Hu, Peng; Wang, Li; Dong, Shaojun

    2013-11-18

    TiO2 nanotube arrays (NTA), prepared by potentiostatic anodization, were discovered to possess an intrinsic peroxidase-like activity. The colorimetric and electrochemical assays both demonstrated their excellent catalytic activity towards H2O2 reduction. On this basis, a simple and inexpensive electrochemical biosensor for glucose detection was developed. PMID:24084751

  12. TiO2 Photocatalytic Degradation of Phenylarsonic Acid

    PubMed Central

    Zheng, Shan; Cai, Yong; O’Shea, Kevin E.

    2010-01-01

    Phenyl substituted arsenic compounds are widely used as feed additives in the poultry industry and have become a serious environmental concern. We have demonstrated that phenylarsonic acid (PA) is readily degraded by TiO2 photocatalysis. Application of the Langmuir–Hinshelwood kinetic model for the initial stages of the TiO2 photocatalysis of PA yields an apparent rate constant (kr) of 2.8 µmol/L·min and the pseudo-equilibrium constant (K) for PA is 34 L/mmol. The pH of the solution influences the adsorption and photocatalytic degradation of PA due to the surface charge of TiO2 photocatalyst and speciation of PA. Phenol, catechol and hydroquinone are observed as the predominant products during the degradation. The roles of reactive oxygen species, •OH, 1O2, O2−• and hVB+ were probed by adding appropriate scavengers to the reaction medium and the results suggest that •OH plays a major role in the degradation of PA. By-products studies indicate the surface of the catalyst plays a key role in the formation of the primary products and the subsequent oxidation pathways leading to the mineralization to inorganic arsenic. TiO2 photocatalysis results in the rapid destruction of PA and may be attractive for the remediation of a variety of organoarsenic compounds. PMID:20473340

  13. The Synthesis of Cadmium Doped Mesoporous TiO2

    SciTech Connect

    Li, Xiaohong S.; Fryxell, Glen E.; Engelhard, Mark H.; Wang, Chong M.

    2007-06-01

    Cd doped mesoporous titanium oxide was prepared using non-ionic surfactants and easily handled titanium precursors. The Cd doping was found to be able to significantly inhibit the growth of anatase crystal size, stabilize the mesoporous structure, and retard the densification of nanoporous TiO2 at elevated temperatures.

  14. 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.

  15. 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

  16. 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.

  17. The synthesis of TiO2 and TiO2-Pt and their application in the removal of Cr (VI).

    PubMed

    Fan, Jian-Wei; Liu, Xiang-Hu; Zhang, Jie

    2011-01-01

    The deposition of noble metal on titanium dioxide (TiO2) has been considered as an effective strategy to improve the activity of TiO2. In this paper, TiO2 nanoparticles were prepared via a sol-gel route, followed by heat treatment at elevated temperatures. TiO2-Pt catalyst was prepared by deposition of platinum (Pt) on the surface of as-prepared TiO2 nanoparticles. TiO2 and TiO2-Pt were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, ultraviolet-visible differential reflectance spectra and infrared spectroscopy. TiO2 and TiO2-Pt were used as heterogeneous catalysts for the removal of Cr (VI) under ultraviolet-light illumination. TiO2 prepared at low temperature had smaller particle size and higher specific surface area, and consequently had higher activity on the removal of Cr (VI). The Pt deposited on the surface of TiO2 favoured the separation of photo-produced electrons (e-) and holes (h+), inhibited the recombination of e- and h+, and enhanced Cr (VI) removal. However, its blocking of active sites also inhibited the removal of Cr (VI). The deposition of 1% (wt.%) Pt to TiO2 produced the optimum activity for the removal of Cr (VI). A lower pH favoured the adsorption of Cr (VI) on the surface of TiO2, and correspondingly enhanced the removal of Cr (VI). PMID:21780710

  18. 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.

  19. A facile hydrothermal approach for construction of carbon coating on TiO2 nanoparticles

    PubMed Central

    Olurode, Kehinde; Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiphing

    2012-01-01

    Herein a facile hydrothermal approach is used to construct carbon coated TiO2 nanoparticles employing dextrose as the source of carbon. The procedure is operated at a low temperature of 200 °C. Fourier infrared spectroscopy demonstrated the successful coating of carbon on TiO2 nanoparticles. The phase composition of TiO2 and carbon coated TiO2 nanoparticles were studied using X-ray diffraction and the surface morphology was analyzed by scanning and transmission electron microscopy. The existence of carbon coating on TiO2 nanoparticles was revealed by thermogravimetric analysis through different thermograms exhibited for TiO2 and carbon coated TiO2 nanoparticles. The reported method offers a simple and efficient approach for production of carbon coating TiO2 nanoparticles. PMID:22297036

  20. Dry-spray deposition of TiO2 for a flexible dye-sensitized solar cell (DSSC) using a nanoparticle deposition system (NPDS).

    PubMed

    Kim, Min-Saeng; Chun, Doo-Man; Choi, Jung-Oh; Lee, Jong-Cheon; Kim, Yang Hee; Kim, Kwang-Su; Lee, Caroline Sunyong; Ahn, Sung-Hoon

    2012-04-01

    TiO2 powders were deposited on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates for application to the photoelectrode of a dye-sensitized solar cell (DSSC). In the conventional DSSC manufacturing process, a semiconductor oxide such as TiO2 powder requires a sintering process at higher temperature than the glass transition temperature (T(g)) of polymers, and thus utilization of flexible polymer substrates in DSSC research has been constrained. To overcome this restriction related to sintering, we used a nanoparticle deposition system (NPDS) that could produce a thin coating layer through a dry-spray method under atmospheric pressure at room temperature. The powder was sprayed through a slit-type nozzle having a 0.4 x 10 mm2 rectangular outlet. In order to determine the deposited TiO2 thickness, five kinds of TiO2 layered specimens were prepared, where the specimens have single and double layer structures. Deposited powders on the ITO coated PET substrates were observed using FE-SEM and a scan profiler The thicker TiO2 photoelectrode with a DSSC having a double layer structure showed higher energy efficiency than the single layer case. The highest fabricated flexible DSSC displayed a short circuit current density J(sc) = 1.99 mA cm(-2), open circuit voltage V(oc) = 0.71 V, and energy efficiency eta = 0.94%. These results demonstrate the possibility of utilizing the dry-spray method to fabricate a TiO2 layer on flexible polymer substrates at room temperature under atmospheric pressure. PMID:22849129

  1. Photocatalytic degradation of diethyl phthalate using TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Singla, Pooja; Pandey, O. P.; Singh, K.

    2014-04-01

    TiO2 nanoparticles predominantly in rutile phase are synthesized by ultrasonication assisted sol-gel method. TiO2 powder is characterized using X-ray powder diffraction and UV-vis diffuse reflectance. TiO2 is used as catalyst in photocatalytic degradation of Diethyl Phthalate. TiO2 exhibits good photocatalytic activity for the degradation of diethyl phthalate.

  2. Photocatalytic synthesis of TiO(2) and reduced graphene oxide nanocomposite for lithium ion battery.

    PubMed

    Qiu, Jingxia; Zhang, Peng; Ling, Min; Li, Sheng; Liu, Porun; Zhao, Huijun; Zhang, Shanqing

    2012-07-25

    In this work, we synthesized graphene oxide (GO) using the improved Hummers' oxidation method. TiO2 nanoparticles can be anchored on the GO sheets via the abundant oxygen-containing functional groups such as epoxy, hydroxyl, carbonyl, and carboxyl groups on the GO sheets. Using the TiO2 photocatalyst, the GO was photocatalytically reduced under UV illumination, leading to the production of TiO2-reduced graphene oxide (TiO2-RGO) nanocomposite. The as-prepared TiO2, TiO2-GO, and TiO2-RGO nanocomposite were used to fabricate lithium ion batteries (LIBs) as the active anode materials and their corresponding lithium ion insertion/extraction performance was evaluated. The resultant LIBs of the TiO2-RGO nanocomposite possesses more stable cyclic performance, larger reversible capacity, and better rate capability, compared with that of the pure TiO2 and TiO2-GO samples. The electrochemical and materials characterization suggest that the graphene network provides efficient pathways for electron transfer, and the TiO2 nanoparticles prevent the restacking of the graphene nanosheets, resulting in the improvement in both electric conductivity and specific capacity, respectively. This work suggests that the TiO2 based photocatalytic method could be a simple, low-cost, and efficient approach for large-scale production of anode materials for lithium ion batteries. PMID:22738305

  3. TiO2/methylcellulose nanocomposite films for photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Rosu, M. C.; Suciu, R. C.; Dreve, S. V.; Silipas, T. D.; Bratu, I.; Indrea, E.

    2012-02-01

    TiO2/methylcellulose (MeC) nanocomposite films were obtained by wet-chemical techniques using MeC and/or additives (acetylacetone, polyethylene glycol and Triton X-100). Thin films were obtained by spin-coating the colloidal suspensions on conductive indium tin oxide (ITO) glass, followed by a heat-treatment. The effect of MeC and additives on TiO2 nanoparticles dispersion was investigated by FTIR microscopy and X-ray diffraction (for structural and morphological properties), UV-VIS absorption spectroscopy and spectrofluorimetry (for optoelectronic properties) and wet technique adhesion test (for mechanical integrity). The composite film with methylcellulose and additives has good integrity and better adhesion to ITO substrate, without losing its photocatalytic activity. The results of these experiments showed that such nanocomposite films are interesting candidate for applications in the field of photocatalytic degradation of organic pollutants.

  4. Hydrogenation and disorder in engineered black TiO2.

    PubMed

    Liu, Lei; Yu, Peter Y; Chen, Xiaobo; Mao, Samuel S; Shen, D Z

    2013-08-01

    A new form of TiO2 which is black in color has been shown to exhibit high efficiency for photocatalytic reactions under solar radiation [X. Chen, L. Liu, P. Y. Yu, and S. S. Mao, Science 331, 746 (2011)]. However, the mechanism behind this disorder-engineering process is not fully understood. In this Letter, based on density functional theory, we describe the role of hydrogen in producing lattice disorder in the anatase nanocrystals. We clarify further that the highly localized nature of the midgap states results in spatial separation of photoexcited electrons and holes in black TiO2, and that accounts for its high photocatalytic efficiency. PMID:23971586

  5. 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. PMID:23427896

  6. Photocatalytic Activity of Immobilized Geometries of TiO2

    NASA Astrophysics Data System (ADS)

    Koohestani, Hassan; Sadrnezhaad, Sayed Khatiboleslam

    2015-07-01

    Photocatalysts that are used for waste water treatment are often suspended in the waste water during processing and then must be removed from the water after treatment. To reduce the post-degradation expenses and time, separation is facilitated by an immobilization process. The effect of immobilized TiO2 geometries on the photocatalytic behavior of the photocatalyst is investigated in this work. Powder, fiber, film, and network-shaped TiO2 nanocatalysts were produced by using different templates. The cellulose fiber and ceramic templates were used as substrates for fiber and film/network geometry production. The products were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurement. The photocatalytic performance was determined by methyl orange degradation and cyanide photo-oxidation under ultraviolet irradiation. From the SEM images, the size range of the TiO2 particles in the film and in the network geometries were 20-60 nm. The nanoparticles had covered the surface of the substrate, uniformly. Removal of the cellulose substrate by heat treatment yielded hollow TiO2 fibers with diameters of 0.5-1 µm and lengths of 30 µm. The efficiencies of both photocatalytic reactions were obtained in the following order: powder > network > film > fiber geometry. The rate constant of the dye degradation reaction using powder catalyst was 0.0118 min-1. For network catalyst, it was 0.0083 min-1. Corresponding results for cyanide disinfection were 0.0055 and 0.0046 min-1. Although powder samples had higher rate constants, network geometry was preferred due to its higher immobility.

  7. Methanethiol Chemistry on TiO2-Supported Ni Clusters

    SciTech Connect

    Ozturk,O.; Park, J.; Black, T.; Rodriguez, J.; Hrbek, J.; Chen, D.

    2008-01-01

    The thermal decomposition of methanethiol on Ni clusters grown on TiO2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiOx and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

  8. Methanethiol chemistry on TiO 2-supported Ni clusters

    NASA Astrophysics Data System (ADS)

    Ozturk, O.; Park, J. B.; Black, T. J.; Rodriguez, J. A.; Hrbek, J.; Chen, D. A.

    2008-10-01

    The thermal decomposition of methanethiol on Ni clusters grown on TiO 2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO 2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO 2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO 2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiO x and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Characteristics of dye-sensitized solar cell with TiO2 anode under UV irradiation

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Kwei; Hsiao, Chih-Chen; Weng, Hao-Wei

    2016-03-01

    The anatase phase crystalline quality of commercial TiO2 (P25) nanoparticle sintered in air and N2 is improved. Compared DSSC with air-sintered TiO2 anode, DSSC with N2-sintered TiO2 anode has better performance mainly from high optical absorption efficiency. Under UV irradiation, organic contaminants adsorbed on TiO2 are dissociated by the photocatalysis, and the dye adsorption is enhanced. The DSSC performance with UV-treated/N2-sintered TiO2 anode is further improved.

  14. Photocatalytic degradation of textile dyestuffs using TiO2 nanotubes prepared by sonoelectrochemical method

    NASA Astrophysics Data System (ADS)

    Tekin, Derya

    2014-11-01

    TiO2 nanotubes were prepared by anodization of Ti plates by conventional electrochemical technique as well as by an emerging sonoelectrochemical technique. Scanning electron miscroscope (SEM) analysis showed that ultrasound assisted anodization yielded more ordered and controllable TiO2 tube banks with higher tube diameter. The photocatalytical activities of TiO2 nanotubes were tested in the photocatalytical degradation of Orange G dye. The results showed that sonoelectrochemically prepared TiO2 tubes exhibited 10% higher photocatalytic performance than the electrochemical prepared ones, and more than 18% higher activity than the other TiO2 samples.

  15. In situ processed gold nanoparticle-embedded TiO2 nanofibers enabling plasmonic perovskite solar cells to exceed 14% conversion efficiency.

    PubMed

    Mali, Sawanta S; Shim, Chang Su; Kim, Hyungjin; Patil, Pramod S; Hong, Chang Kook

    2016-02-01

    We have demonstrated organometallic perovskite solar cells (PSCs) based on Au decorated TiO2 nanofibers and methylammonium lead iodide (MAPbI3). A power conversion efficiency of 14.92% was achieved, which is significantly higher than that of conventional mesoporous (mp) TiO2, as well as TiO2 nanofiber-based devices. The present synthetic process provides new opportunities for the development of efficient plasmonic PSCs based on metal oxide nanofibers. Solar cells based on these architectures exhibit a short-circuit current density J(SC) of 21.63 ± 0.36 mA cm(-2), V(OC) of 0.986 ± 0.01 V and fill factor of 70% ± 3%, which provide a power conversion efficiency of 14.92% ± 0.33% under standard AM 1.5 conditions. The results of time-resolved photoluminescence (TRPL) spectroscopy and solid-state impedance spectroscopy (ssIS) revealed that PSCs based on Au-decorated TiO2 nanofibers exhibit a low recombination rate. The present results are much higher than those for reported PSCs based on a Au@TiO2 electron-transporting layer (ETL). PMID:26759073

  16. 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.

  17. 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.

  18. A study on electrospun nylon-6/TiO2 composite nanofibers

    NASA Astrophysics Data System (ADS)

    Nirmala, R.; Won, Jeong Jin; Kim, Hak Yong; Navamathavan, R.; Chuan, Yi; El-Newehy, Mohamed; Al-Deyab, Salem S.

    2012-05-01

    We report on the preparation and the characterization of TiO2 nanoparticles incorporated with nylon-6 composite nanofibers by using electrospinning technique. Two different composite nanofiber mats with TiO2 nanoparticles sizes of 20 and 300 nm were prepared. The resultant nanofibers exhibited good incorporation of TiO2 nanoparticles. The doping of TiO2 nanoparticles into the nylon-6 nanofibers was confirmed by using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy. The measurement of the electrical conductivity of the TiO2 nanoparticles incorporated with nylon-6 nanofibers were carried out. Current-voltage (I-V) characteristics revealed that the current was enhanced for the sample with 300 nm TiO2 nanoparticles compared to that with 20-nm TiO2 nanoparticles.

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

    PubMed

    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

  20. 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

  1. Spray deposition of electrospun TiO2 nanorods for dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Fujihara, K.; Kumar, A.; Jose, R.; Ramakrishna, S.; Uchida, S.

    2007-09-01

    A simple technique was developed to fabricate a large-area TiO2 electrode layer using electrospun nanorods for dye-sensitized solar cells (DSSCs). Using this technique, we assembled DSSCs of area ~1 cm2 consisting of a thin TiO2 nanoparticle layer and a thick TiO2 nanorod layer as electrode. The TiO2 nanorods were obtained by mechanically grinding electrospun TiO2 nanofibers. A titania sol was first spin-coated on a conductive glass plate and a TiO2 nanorod layer was next spray dried on it to fabricate TiO2 nanoparticle/nanorod layers. These layers were subsequently sintered. The best-performing DSSC evaluated under AM1.5G (1 sun) condition gave current density ~13.6 mA cm-2, open circuit voltage ~0.8 V, fill factor ~51% and energy conversion efficiency ~5.8%.

  2. 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

  3. 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

  4. 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.

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

    PubMed

    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

  6. 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.

  7. Development of TiO2 and TiO2/Fe-based polymeric nanocomposites by single-step laser pyrolysis

    NASA Astrophysics Data System (ADS)

    Alexandrescu, R.; Morjan, I.; Dumitrache, F.; Scarisoreanu, M.; Fleaca, C. T.; Morjan, I. P.; Barbut, A. D.; Birjega, R.; Prodan, G.

    2013-08-01

    Polymer-based nanocomposites provided with inorganic cores were simultaneously manufactured by the single-step laser pyrolysis. A comparative study was performed on two types of nanocomposites, starting from two different systems: TiO2/methyl methacrylate (MMA) and TiO2/Fe/hexamethyl disiloxane (HMDSO) polymer. The reactive mixture contained TiCl4 as Ti precursor and alternatively, Fe(CO)5 (in case of TiO2/Fe mixture). The analytical techniques used for the characterization indicate distinct morphologies for the obtained nanostructures. Polyhedral and almost spherical nanoparticles in a coalescent matrix and very rare individual core-shell particles are noticed for the TiO2/MMA nanocomposites. Instead, nanoparticles presenting core-shell structures were often present in the TiO2/Fe/HMDSO polymeric nanocomposites.

  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. Hierarchically organized nanostructured TiO2 for photocatalysis applications.

    PubMed

    Di Fonzo, F; Casari, C S; Russo, V; Brunella, M F; Li Bassi, A; Bottani, C E

    2009-01-01

    A template-free process for the synthesis of nanocrystalline TiO2 hierarchical microstructures by reactive pulsed laser deposition (PLD) is here presented. By a proper choice of deposition parameters a fine control over the morphology of TiO2 microstructures is demonstrated, going from classical compact/columnar films to a dense forest of distinct hierarchical assemblies of ultrafine nanoparticles (<10 nm), up to a more disordered, aerogel-type structure. Correspondingly, the film density varies with respect to bulk TiO2 anatase, with a degree of porosity going from 48% to over 90%. These structures are stable with respect to heat treatment at 400 degrees C, which results in crystalline ordering but not in morphological changes down to the nanoscale. Both as deposited and annealed films exhibit very promising photocatalytic properties, even superior to standard Degussa-P25 powder, as demonstrated by the degradation of stearic acid as a model molecule. The observed kinetics are correlated to the peculiar morphology of the PLD grown material. We show that the 3D multiscale hierarchical morphology enhances reaction kinetics and creates an ideal environment for mass transport and photon absorption, maximizing the surface area-to-volume ratio while at the same time providing readily accessible porosity through the large inter-tree spaces that act as distributing channels. The reported strategy provides a versatile technique to fabricate high aspect ratio 3D titania microstructures through a hierarchical assembly of ultrafine nanoparticles. Beyond photocatalytic and catalytic applications, this kind of material could be of interest for those applications where high surface-to-volume and efficient mass transport are required at the same time. PMID:19417258

  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. 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. PMID:26164250

  12. 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. PMID:22760594

  13. 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.

  14. 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.

  15. Activity of laccase immobilized on TiO2-montmorillonite complexes.

    PubMed

    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

  16. 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.

  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. Role of Cl - ions in photooxidation of propylene on TiO 2 surface

    NASA Astrophysics Data System (ADS)

    Guo, Jianhui; Mao, Liqun; Zhang, Jiwei; Feng, Caixia

    2010-01-01

    The effect of Cl - ions on photooxidation of propylene on TiO 2 semiconductor was investigated. Cl -/TiO 2 catalysts were prepared by annealing Degussa P25 TiO 2 in the gas flow of N 2 and Cl 2 under 100-400 °C. The photocatalytic oxidation of propylene was carried out in a continuous flow system, with the chromatograph to analyze the products on line. The experimental results showed that the activity of Cl -/TiO 2 catalysts increased as heat-treated temperature decreased. The activity of the sample heat-treated at 100 °C was about two times higher than that of pure TiO 2. Moreover, as to TiO 2, the main product of the propylene photocatalytic oxidation was CO 2, but with Cl -/TiO 2 catalysts, not only CO 2 but also trace CO was determined. The adsorbed species on TiO 2 surface before and after reaction were analyzed by X-ray photoelectron spectroscopy (XPS) and thermogravimetric/differential thermal analyses (TG-DTA) coupled to a mass spectrometer (MS). XPS analysis showed that there was Cl - absorbed on the Cl -/TiO 2 surface, and the absorption amount of Cl - decreased after the photooxidation reaction of propylene. TG-DTA-MS analysis confirmed chlorine absorbed on the surface of TiO 2 in the form of Cl - ion. These results illuminated that absorbed Cl - on the surface of TiO 2 formed a weak physical absorption on TiO 2 at low temperature, and subsequently participated in the photooxidation of propylene, finally removed from TiO 2 surface.

  19. Preparation of rutile TiO(2) coating by thermal chemical vapor deposition for anticoking applications.

    PubMed

    Tang, Shiyun; Wang, Jianli; Zhu, Quan; Chen, Yaoqiang; Li, Xiangyuan

    2014-10-01

    To inhibit the metal catalytic coking and improve the oxidation resistance of TiN coating, rutile TiO2 coating has been directly designed as an efficient anticoking coating for n-hexane pyrolysis. TiO2 coatings were prepared on the inner surface of SS304 tubes by a thermal CVD method under varied temperatures from 650 to 900 °C. The rutile TiO2 coating was obtained by annealing the as-deposited TiO2 coating, which is an alternative route for the deposition of rutile TiO2 coating. The morphology, elemental and phase composition of TiO2 coatings were characterized by SEM, EDX and XRD, respectively. The results show that deposition temperature of TiO2 coatings has a strong effect on the morphology and thickness of as-deposited TiO2 coatings. Fe, Cr and Ni at.% of the substrate gradually changes to 0 when the temperature is increased to 800 °C. The thickness of TiO2 coating is more than 6 μm and uniform by metalloscopy, and the films have a nonstoichiometric composition of Ti3O8 when the deposition temperature is above 800 °C. The anticoking tests show that the TiO2 coating at a deposition temperature of 800 °C is sufficiently thick to cover the cracks and gaps on the surface of blank substrate and cut off the catalytic coke growth effect of the metal substrate. The anticoking ratio of TiO2 coating corresponding to each 5 cm segments is above 65% and the average anticoking ratio of TiO2 coating is up to 76%. Thus, the TiO2 coating can provide a very good protective layer to prevent the substrate from severe coking efficiently. PMID:25192018

  20. 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.

  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. 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.

  3. Electronic properties of vanadium-doped TiO2.

    PubMed

    Islam, Mazharul M; Bredow, Thomas; Gerson, Andrea

    2011-12-01

    The electronic properties of vanadium-doped rutile TiO(2) are investigated theoretically with a Hartree-Fock/DFT hybrid approach. The most common oxidation states (V(2+), V(3+), V(4+), and V(5+)) in different spin states are investigated and their relative stability is calculated. The most stable spin states are quartet, quintet, doublet, and singlet for V(2+), V(3+), V(4+), and V(5+) doping, respectively. By comparing the formation energy with respect to the parent oxides and gas-phase oxygen (ΔE), we conclude that V(4+) (ΔE=145.3 kJ mol(-1)) is the most likely oxidation state for vanadium doping with the possibility of V(5+) doping (ΔE=283.5 kJ mol(-1)). The energetic and electronic properties are converged with dopant concentrations in the range of 0.9 to 3.2%, which is within the experimentally accessible range. The investigation of electronic properties shows that V(4+) doping creates both occupied and unoccupied vanadium states in the band gap and V(5+) doping creates unoccupied states at the bottom of the conduction band. In both cases there is a significant reduction of the band gap by 0.65 to 0.75 eV compared to that of undoped rutile TiO(2). PMID:22025455

  4. Birefringence enhancement in annealed TiO2 thin films

    NASA Astrophysics Data System (ADS)

    van Popta, Andy C.; Cheng, June; Sit, Jeremy C.; Brett, Michael J.

    2007-07-01

    Postdeposition thermal annealing is used to enhance the form birefringence of nanostructured TiO2 thin films grown by electron-beam evaporation using the serial bideposition technique. Thin films were grown on fused silica substrates using oblique deposition angles between 60° and 75° and repetitive 180° substrate rotations to produce birefringent thin films that are structurally anisotropic. Postdeposition annealing in air, between 200 and 900°C, was used to increase the form birefringence of the films by changing the TiO2 phase from the as-deposited amorphous state to a polycrystalline state that exhibits a greater inherent density and larger bulk refractive index. The optical properties, microstructure, and crystallinity were characterized by Mueller matrix ellipsometry, scanning electron microscopy, atomic force microscopy, and x-ray diffraction. It was found that the in-plane birefringence increased significantly upon thermal annealing, in some cases yielding birefringence values that doubled in magnitude, from 0.11 to 0.22 at a wavelength of 550nm for films annealed at 400°C.

  5. Composite WO3/TiO2 nanostructures for high electrochromic activity.

    PubMed

    Reyes-Gil, Karla R; Stephens, Zachary D; Stavila, Vitalie; Robinson, David B

    2015-02-01

    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 performance were studied. 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. PMID:25562778

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  8. Two-Dimensional Hollow TiO2 Nanoplates with Enhanced Photocatalytic Activity.

    PubMed

    Song, Chuang; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-04-25

    Two-dimensional anatase TiO2 hollow nanoplates were firstly synthesized through a facile synthesis route by using α-Fe2 O3 nanoplates as removable templates. Two-dimensional hollow TiO2 nanoplates with different ratios of anatase and rutile phases were obtained by adjusting the calcining temperature. The average diameters were around 600 nm, and the shell thickness was approximately 30 nm. The photocatalytic performance of TiO2 was investigated by decomposing rhodamine B under simulated sunlight. Among the TiO2 samples, the anatase TiO2 hollow nanoplates manifested a significant enhancement in the photocatalytic performances. The excellent catalytic performance can be attributed to the unique structure of the two-dimensional anatase TiO2 hollow nanoplates, including a large surface area and increased dye-photocatalyst contact areas as well as more active sites for photodegradation. PMID:26996999

  9. 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.

  10. 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

  11. 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.

  12. Synthesis and characterization of TiO2 and Ag/TiO2 nanostructure

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Thakur, Amit Kumar; Kulshrestha, Vaibhav; Shahi, V. K.

    2013-02-01

    Single phase anatase TiO2 nanoparticles were prepared using Titanium tertachloride (TiCl4) as precursor through an inexpensive method. Well dispersed nanocomposites of silver at TiO2 were synthesized successfully by photochemical route. Both TiO2 and Ag/TiO2 were characterized using X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). The particle size of TiO2 is found to be ˜ 11 nm and ˜ 22 nm for Ag/TiO2, by XRD and confirmed by TEM. TEM micrographs also show the single phase crystal of TiO2 and confirm the deposition of silver among TiO2.

  13. Photocatalytic degradation of monoethanolamine in wastewater using nanosized TiO2 loaded on clinoptilolite

    NASA Astrophysics Data System (ADS)

    Khodadoust, Saeid; Sheini, Azarmidokht; Armand, Nezam

    2012-06-01

    The use of titanium dioxide (TiO2) as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. In this investigation photocatalytic degradation of monoethanolamine (MEA) using TiO2 (in form of anatase) loaded on surface of clinoptilolite (CP) (TiO2-CP) in wastewater was studied. The surface interaction between TiO2 and CP was investigated by means of transmission electron microscope (TEM), atom force microscope (AFM), IR and X-ray diffraction (XRD). Then the effects of some parameters such as pH, amount of photocatalyst, and initial concentration of MEA on degradation percentage of MEA were examined. The obtained results show that the TiO2-CP is an active photocatalyst as compared with TiO2 nanopowders. All these results indicated that this proposed method can be useful for the development of wastewater treatment applications.

  14. 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

  15. 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.

  16. Enhanced magnetoresistance in half-metallic CrO2-TiO2 composites

    NASA Astrophysics Data System (ADS)

    Fan, Yinbo; Zhang, Caiping; Du, Xiaobo; Wen, Gehui; Ma, Hongan; Jia, Xiaopeng

    2013-06-01

    CrO2-TiO2 composites were synthesized by a high temperature and high pressure method (HTHP). The CrO2-TiO2 composites are composed of large rod-like CrO2 crystals separated by TiO2 nanoparticles. The saturation magnetization of the CrO2 in the composites is very close to the theoretical value. The CrO2-TiO2 composites show greatly enhanced magnetoresistance than that of pure CrO2. This is mainly attributed to spin-dependent tunneling between adjacent CrO2 grains enhanced by the addition of TiO2. The tunneling mechanism in the composites can be best described by the fluctuation-induced tunneling model as convinced by the temperature dependence of the conductivity of the CrO2-TiO2 composites at low temperature.

  17. 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

  18. 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.

  19. Orientated anatase TiO2 nanocrystal array thin films for self-cleaning coating.

    PubMed

    Zhao, Zhao; Tan, Huaqiao; Zhao, Haifeng; Li, Di; Zheng, Min; Du, Peng; Zhang, Guoqiang; Qu, Dan; Sun, Zaicheng; Fan, Hongyou

    2013-10-11

    We developed a simple method to synthesize TiO2 nanowire arrays with nearly 100% exposed {001} facets. The coating exhibits good transparency. The thin films of TiO2 nanowire arrays display a very good photocatalytic degradation of dye molecules and good durability. Based on the above features, the TiO2 nanowire array coating is advantageous for self-cleaning coating. PMID:23963053

  20. 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

  1. 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. PMID:26223014

  2. 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.

  3. 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.

  4. 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

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

    PubMed

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

    2016-12-01

    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. PMID:27389344

  6. Determination of electron and hole lifetimes of rutile and anatase TiO2 single crystals

    NASA Astrophysics Data System (ADS)

    Yamada, Yasuhiro; Kanemitsu, Yoshihiko

    2012-09-01

    The dynamical behavior of photoexcited states of TiO2 governs the activities of TiO2-based solar cells and photocatalysts. We determined the lifetimes of photoexcited electrons and holes in rutile and anatase TiO2 single crystals by combining advantages of time-resolved photoluminescence, photoconductance, and transient absorption spectroscopy. Electrons and holes in rutile show exponential decays with the lifetime of a few tens of nanoseconds, while non-exponential decays are observed in anatase, indicating the presence of multiple carrier trapping processes. We revealed the generic features of the carrier recombination processes in rutile and anatase TiO2.

  7. Solubility of TiO2 in Olivine from 1 to 8 Gpa

    NASA Astrophysics Data System (ADS)

    Tinker, D.; Lesher, C. E.

    2001-12-01

    Laboratory experiments have been conducted to determine the solubility of TiO2 in olivine from 1 to 8 GPa, between 1127° and 1560° C. These experiments were performed in the piston cylinder device (1 and 2 GPa) and the MA6/MA8 multianvil apparatus (3 to 8 GPa), using starting materials consisting of San Carlos olivine and 20 wt % TiO2 powder. Excess TiO2 forms rutile in all run products. The presence of rutile imposes unit activity of TiO2 in olivine and, thus, we measure maximum solubilities of Ti in olivine. This situation differs from studies in which olivine is in equilibrium with ilmenite [1,2,3]. Electron microprobe analyses of run products show that the TiO2 content of olivine has positive pressure dependence between 1 and 8 GPa. Olivine contains 0.2 wt % TiO2 between 1 and 3 GPa, at 1127° and 1460° C; TiO2 contents increase to 0.5 wt % between 3 and 8 GPa. Dobrzhinetskaya et al. [1] and Green et al. [2] observed a similar positive pressure dependence on TiO2 solubility in olivine between 6 and 14 GPa. However, TiO2 contents of olivine from 6 to 8 GPa in these studies are lower than TiO2 contents we find between 6 and 8 GPa. Lower TiO2 contents presumably reflect ilmenite-olivine equilibria. In contrast, Okamoto et al. [3] and Ulmer and Trommsdorff [4] did not report a positive pressure dependence on TiO2 solubility in olivine, although rutile was stable in the experiments of [4]. The positive pressure dependence of TiO2 solubility is important for the interpretation of high pressure metamorphic rocks containing abundant exsolved titanate rods, which on recombination can yield 0.6 wt % TiO2 in host olivine before exsolution [5]. We estimate from our data that olivine containing 0.6 wt % TiO2 originated at a minimum depth of 10 GPa. The positive pressure dependence of TiO2 in olivine offers an additional pathway for the transport of Ti and other high field strength elements into the mantle, and these elements may later be recovered by rising mantle plumes. [1] Dobrzhinetskaya et al. (2000) Chem. Geol., 163, 325-338; [2] Green et al. (1997) Tectonics, 279, 1-21; [3] Okamoto et al. (1997) EOS, F761; [4] Ulmer and Trommsdorff (1997) TERRA, 9, 39; [5] Green et al. (1997) Science, 278, 704-707

  8. 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.

  9. 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.

  10. 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

  11. 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.

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

    PubMed

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

    2015-01-01

    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 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. PMID:26044406

  13. Synthesis, characterization and photocatalytic activity of 1D TiO2 nanostructures.

    PubMed

    Cabrera, Julieta; Alarcón, Hugo; López, Alcides; Candal, Roberto; Acosta, Dwight; Rodriguez, Juan

    2014-01-01

    Nanowire/nanorod TiO(2) structures of approximately 8 nm in diameter and around 1,000 nm long were synthesized by alkaline hydrothermal treatment of two different TiO(2) nanopowders. The first precursor was TiO(2) obtained by the sol-gel process (SG-TiO(2)); the second was the well-known commercial TiO(2) P-25 (P25-TiO(2)). Anatase-like 1D TiO(2) nanostructures were obtained in both cases. The one-dimensional (1D) nanostructures synthesized from SG-TiO(2) powders turned into rod-like nanostructures after annealing at 400 °C for 2 h. Conversely, the nanostructures synthesized from P25-TiO(2) preserved the tubular structure after annealing, displaying a higher Brunauer-Emmett-Teller surface area than the first system (279 and 97 m²/g, respectively). Despite the higher surface area shown by the 1D nanostructures, in both cases the photocatalytic activity was lower than for the P25-TiO(2) powder. However, the rod-like nanostructures obtained from SG-TiO(2) displayed slightly higher efficiency than the sol-gel prepared powders. The lower photocatalytic activity of the nanostructures with respect to P-25 can be associated with the lower crystallinity of 1D TiO(2) in both materials. PMID:25259484

  14. 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.

  15. Beta zeolite supported sol-gel TiO2 materials for gas phase photocatalytic applications.

    PubMed

    Lafjah, Mama; Djafri, Fatiha; Bengueddach, Abdelkader; Keller, Nicolas; Keller, Valérie

    2011-02-28

    Beta zeolite supported sol-gel TiO(2) photocatalytic materials were prepared according to a sol-gel route in which high specific surface area Beta zeolite powder was incorporated into the titanium isopropoxide sol during the course of the sol-gel process. This led to an intimate contact between the zeolite surface and the TiO(2) precursors, and resulted in the anchorage of large amounts of dispersed TiO(2) nanoparticles and in the stabilization of TiO(2) in its anatase form, even for high TiO(2) wt. contents and high calcination temperatures. Taking the UV-A photocatalytic oxidation of methanol as gas phase target reaction, high methanol conversions were obtained on the Beta zeolite supported TiO(2) photocatalysts when compared to bulk sol-gel TiO(2), despite lower amounts of TiO(2) within the photoactive materials. The methanol conversion was optimum for about 40 wt.% TiO(2) loading and calcination temperatures of 500-600°C. PMID:21177024

  16. 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.

  17. 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

  18. Amorphous TiO2 nanotube-derived synthesis of highly ordered anatase TiO2 nanorod arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Cong; Zhu, Dachuan; Cao, Shixiu

    2016-02-01

    A facile method by combining anodic oxidation and hydrothermal method was developed to construct highly ordered anatase TiO2 nanorods (TNRs) and nanotubes (TNTs). In this method, the anodic oxidation was used for preparing highly ordered amorphous TNTs, which subsequently served as highly ordered template for next reaction process. Upon hydrothermal treatment, the as-anodized amorphous template got converted to highly ordered anatase TNTs (blank sample) in without cobalt nitrate solution and TNRs (doped sample) in cobalt nitrate solution, respectively. To our best knowledge, this is first successful attempt to prepare highly ordered anatase TNRs based on the above amorphous template. The scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicate that the as-prepared anatase TNRs are composed by a large number of anatase TiO2 nanoparticles (TNPs) and the morphology at top of TNRs is different from that of its trunk. Details of the morphology, phase transformation, and growth mechanism of the obtained TNRs are discussed. In addition, the role of Co2+ in the crystallization process had been also discussed.

  19. 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.

  20. 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.

  1. 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%. PMID:26369182

  2. 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

  3. Modelling of nanostructured TiO2-based memristors

    NASA Astrophysics Data System (ADS)

    Shinde, S. S.; Dongle, T. D.

    2015-03-01

    The fourth fundamental circuit element memristor completes the missing link between charge and magnetic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the memristor depends on the magnitude and direction of applied potential. This unique property makes it the primitive building block for many applications such as resistive memories, soft computing, neuromorphic systems and chaotic circuits etc. In this paper we report TiO2-based nanostructured memristor modelling. The present memristor model is constructed in MATLAB environment with consideration of the linear drift model of memristor. The result obtained from the linear drift model is well matched with earlier reported results by other research groups.

  4. Imaging Surface Reactions of Formaldehyde on TiO2

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenrong; Tang, Miru; Wang, Zhi-Tao; Ke, Zhu; Xia, Yaobiao; Park, Kenneth; Lyubinetsky, Igor; Dohnálek, Zdenek; Ge, Qingfeng

    2015-03-01

    Formaldehyde is involved in many surface catalytic and photo-catalytic reactions on metal oxides. We studied surface reactions of formaldehyde on reduced TiO2(110) surfaces using variable-temperature scanning tunneling microscopy (STM) and density functional theory (DFT). STM images taken from a same area at various temperatures clearly show that formaldehyde preferentially adsorbs on the bridge-bonded oxygen vacancy (VO) defect sites. Bias-dependent STM images suggest the bonding configurations of the Ti-bound CH2O and the VO-bound CH2O. The isothermal time dependent images show the rotation of VO-bound CH2O and the two diffusion channels of formaldehyde at different temperatures. We also directly observed the formation of formaldehyde dimmer.

  5. Antioxidant defences and haemocyte internalization in Limnoperna fortunei exposed to TiO2 nanoparticles.

    PubMed

    Girardello, Francine; Leite, Camila Custódio; Branco, Catia Santos; Roesch-Ely, Mariana; Fernandes, Andreia Neves; Salvador, Mirian; Henriques, João Antonio Pêgas

    2016-07-01

    TiO2 nanoparticles (TiO2-NP) have been incorporated into a large range of materials for different applications in the last decades and are very likely to appear in wastewater and effluents, eventually reaching the aquatic environment. Therefore, the assessment of the biological impact of TiO2-NP on aquatic ecosystem is of a major concern. The mussels represent a target group for TiO2-NP toxicity, as they are filter feeders and are capable of bioaccumulating toxic compounds. Furthermore, the exotic organism Limnoperna fortunei, golden mussel, is a freshwater bivalve that has been used in biomonitoring environmental conditions. In this work, the TiO2-NP's ability to interact with haemocytes of golden mussel was assessed by transmission electron microscopy. The enzymatic and non-enzymatic antioxidant defenses were evaluated by superoxide dismutase (Sod) and catalase (Cat) activities and protein sulfhydryl content, which were measured after the golden mussel was exposed to TiO2-NP (1, 5, 10 and 50μgmL(-1)). Results demonstrate that TiO2-NP was internalized by cells, causing alterations in haemocytes membrane. Antioxidant activity of Sod and Cat decreased after 2h TiO2-NP exposure. After 4h exposure, the enzymatic antioxidant activity was restored. Notably, the protein sulfhydryl content decreased after 2h to all the TiO2-NP concentrations and no alterations were observed after 4h of TiO2-NP exposure. These results demonstrate the potential of golden mussel as sentinel organism to TiO2-NP exposure. PMID:27152940

  6. 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

  7. 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.

  8. Water diffusion on TiO2 anatase surface

    NASA Astrophysics Data System (ADS)

    Agosta, L.; Gala, F.; Zollo, G.

    2015-06-01

    Compatibility between biological molecules and inorganic materials, such as crystalline metal oxides, is strongly dependent on the selectivity properties and the adhesion processes at the interface between the two systems. Among the many different aspects that affect the adsorption processes of peptides or proteins onto inorganic surfaces, such as the charge state of the amino acids, the peptide 3D structure, the surface roughness, the presence of vacancies or defects on and below the surface, a key role is certainly played by the water solvent whose molecules mediate the interaction. Then the surface hydration pattern may strongly affect the adsorption behavior of biological molecules. For the particular case of (101) anatase TiO2 surface that has a fundamental importance in the interaction of biocompatible nano-devices with biological environment, it was shown, both theoretically and experimentally, that various hydration patterns are close in energy and that the water molecules are mobile at as low temperature values as 190 K. Then it is important to understand the dynamical behavior of first hydration layer of the (101) anatase surface. As a first approach to this problem, density functional calculations are used to investigate water diffusion on the (101) anatase TiO2 surface by sampling the potential energy surface of water molecules of the first hydration layer thus calculating the water molecule migration energy along some relevant diffusion paths on the (101) surface. The measured activation energy of water migration seems in contrast with the observed surface mobility of the water molecules that, as a consequence could be explained invoking a strong role of the entropic term in the context of the transition state theory.

  9. The Effects of Anchor Groups on (1) TiO2-Catalyzed Photooxidation and (2) Linker-Assisted Assembly on TiO2

    NASA Astrophysics Data System (ADS)

    Anderson, Ian Mark

    Quantum dot-sensitized solar cells (QDSSCs) are a popular target for research due to their potential for highly efficient, easily tuned absorption. Typically, light is absorbed by quantum dots attached to a semiconductor substrate, such as TiO2, via bifunctional linker molecules. This research aims to create a patterned monolayer of linker molecules on a TiO2 film, which would in turn allow the attachment of a patterned layer of quantum dots. One method for the creation of a patterned monolayer is the functionalization of a TiO2 film with a linker molecule, followed by illumination with a laser at 355 nm. This initiates a TiO 2-catalyzed oxidation reaction, causing loss of surface coverage. A second linker molecule can then be adsorbed onto the TiO2 surface in the illuminated area. Towards that end, the behaviors of carboxylic and phosphonic acids adsorbed on TiO2 have been studied. TiO2 films were functionalized by immersion in solutions a single adsorbate and surface coverage was determined by IR spectroscopy. It is shown that phosphonic acids attain higher surface coverage than carboxylic acids, and will displace them from TiO2 when in a polar solvent. Alkyl chain lengths, which can influence stabilities of monolayers, are shown not to have an effect on this relationship. Equilibrium binding data for the adsorption of n-hexadecanoic acid to TiO2 from a THF solution are presented. It is shown that solvent polarity can affect monolayer stability; carboxylates and phosphonates undergo more desorption into polar solvents than nonpolar. Through illumination, it was possible to remove nearly all adsorbed linkers from TiO2. However, the illuminated areas were found not to be receptive to attachment by a second adsorbate. A possible reason for this behavior is presented. I also report on the synthesis and characterization of a straight-chain, thiol-terminated phosphonic acid. Initial experiments involving monolayer formation and quantum dot attachment are presented. Finally, it was found that quantum dots attach in high amounts to linker-functionalized TiO2 when suspended in pyridine. This increased surface attachment was present even when the linker molecule used lacked a functional group which would bind to the CdSe surface.

  10. 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.

  11. 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

  12. 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. PMID:26754938

  13. 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.

  14. 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.

  15. 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.

  16. Hierarchical TiO2 flowers built from TiO2 nanotubes for efficient Pt-free based flexible dye-sensitized solar cells.

    PubMed

    Lei, Bing-Xin; Luo, Qiu-Ping; Yu, Xiao-Yun; Wu, Wu-Qiang; Su, Cheng-Yong; Kuang, Dai-Bin

    2012-10-14

    A novel hierarchical TiO(2) flower consisting of anatase TiO(2) nanotubes on a Ti foil substrate has been prepared via a mild hydrothermal reaction of TiO(2) nanoparticles/Ti foil. The photovoltaic performance of DSSC based on hierarchical TiO(2) flowers/Ti (7.2%) is much higher than that of TiO(2) nanoparticle/Ti (6.63%) because of its superior light scattering ability and fast electron transport. Moreover, full flexible DSSC based on the novel hierarchical TiO(2) flowers/Ti foil photoelectrode and electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) on indium tin oxide-coated poly(ethylene terephthalate) (ITO-PET) counter electrode shows a significant power conversion efficiency of 6.26%, accompanying a short-circuit current density of 11.96 mA cm(-2), an open-circuit voltage of 761 mV and a fill factor of 0.69. PMID:22914771

  17. 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

  18. 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.

  19. 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

  20. Superstructure of TiO2 Crystalline Nanoparticles Yields Effective Conduction Pathways for Photogenerated Charges.

    PubMed

    Bian, Zhenfeng; Tachikawa, Takashi; Majima, Tetsuro

    2012-06-01

    Materials with intricate nanostructures display fascinating properties, which have inspired extensive research on the synthesis of materials with controlled structures. In this study, we investigated the properties of superstructures of TiO2 to understand the inter-relationship between structural ordering and photocatalytic performance. The nanoplate anatase TiO2 mesocrystals were chosen as the typical investigation objects, which were newly synthesized by a topotactic structural transformation. The TiO2 mesocrystals displayed the superstructure of crystallographically ordered alignment of anatase TiO2 nanocrystals with high surface area and large high-energy surface {001} planes exposed. The photoconductive atomic force microscopy and time-resolved diffuse reflectance spectroscopy were utilized to determine the charge transport properties of TiO2 mesocrystals, and their features were highlighted by a comparison with reference TiO2 samples, for example, anatase TiO2 nanocrystals with similar surface area and single crystal structure. Consequently, it was found for the first time that such a superstructure of TiO2 could largely enhance charge separation and had remarkably long-lived charges, thereby exhibiting greatly increased photoconductivity and photocatalytic activity. PMID:26285616

  1. 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.

  2. 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

  3. Electrospinning processed nanofibrous TiO(2) membranes for photovoltaic applications.

    PubMed

    Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

    2006-02-28

    We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO(2) membranes as electrode materials. A thin TiO(2) film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF(4) aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO(2) film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO(2) membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO(2) membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N(')-bis(2,2(')-bipyridyl-4,4(')-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO(2) film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO(2) membranes. The efficiency of the fibrous TiO(2) photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%. PMID:21727376

  4. Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

    2006-02-01

    We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

  5. Adsorption properties and photocatalytic activity of TiO2/activated carbon fiber composite

    NASA Astrophysics Data System (ADS)

    Yao, Shuhua; Song, Shuangping; Shi, Zhongliang

    2014-06-01

    Photocatalysts of titanium dioxide (TiO2) and TiO2/activated carbon fiber (TiO2/ACF) composite were prepared by sol-gel method, followed by calcining the pure TiO2 sols and the TiO2/ACF sols at 500°C for 2 h in a N2 atmosphere, respectively. These photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms measurement. Batch experiments were conducted to study the adsorption property of TiO2/ACF composite using methylene blue as adsorbate. The adsorption data obtained from different batch experiments were analyzed using pseudo-second-order kinetic model, the experimental data can be adequately described by the pseudo-second-order equation. The photodecomposition behavior of TiO2/ACF was investigated in aqueous solution using methylene blue as target pollutant. It was found that methylene blue could be removed rapidly from water by TiO2/ACF, the photocatalytic decomposition was obviously improved when the photocatalyst was used. Kinetics analysis revealed that the photocatalytic decomposition reaction can be described well by a first-order rate equation.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. Reprint of: photostability of wool fabrics coated with pure and modified TiO2 colloids.

    PubMed

    Pakdel, Esfandiar; Daoud, Walid A; Sun, Lu; Wang, Xungai

    2015-06-01

    The surface of wool fabrics was coated with TiO2 and TiO2-based nanocomposite colloids and the impact of this coating on the photostability of wool was investigated. TiO2 along with TiO2/Metal and TiO2/Metal/SiO2 sols were synthesized through a low-temperature sol-gel method and applied to fabrics. Composite colloids were synthesized through integrating the silica and three noble metals of silver (Ag), gold (Au) and platinum (Pt) into the synthesis process of sols. Four different molar ratios of Metal to TiO2 (0.01%, 0.1%, 0.5% and 1%) were used to elucidate the role of metal type and amount on the obtained features. Photostability and UV protection features of fabrics were evaluated through measuring the photo-induced chemiluminescence (PICL), photoyellowing rate and ultraviolet protection factor (UPF) of fabrics. PICL and photoyellowing tests were carried out under UVA and UVC light sources, respectively. PICL profiles demonstrated that the presence of pure and modified TiO2 nanoparticles on fabrics reduced the intensity of PICL peak indicating a lower amount of polymer free radicals in coated wool, compared to that of pristine fabric. Moreover, a higher PICL peak intensity as well as photoyellowing rate was observed on fabrics coated with modified colloids in comparison with pure TiO2. The surface morphology of fabrics was further characterized using FESEM images. PMID:25746934

  12. 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

  13. TiO2 photoanode sensitized with nanocrystalline Bi2S3: the effect of sensitization time and annealing on its photovoltaic performance

    NASA Astrophysics Data System (ADS)

    Kulkarni, Anil N.; Rajendra Prasad, M. B.; Pathan, Habib M.; Patil, Rajendra S.

    2016-04-01

    This work deals with the sensitization of the porous TiO2 films of thickness about 4 µm deposited on fluorine-doped tin oxide with nanocrystalline Bi2S3 for photovoltaic application. The sensitization was achieved for four different sensitization times employing chemical solution deposition with bismuth nitrate and sodium thiosulphate as precursors for Bi3+ and S2-, respectively. The unsensitized and sensitized photoelectrodes were characterized using X-ray diffractometry, scanning electron microscopy and diffused reflectance spectroscopy. XRD patterns show the signatures of both anatase TiO2 and orthorhombic Bi2S3 in the sensitized photoanodes. However, crystallinity of Bi2S3 increased with increase in sensitization time from 10 to 40 min. The temporal effect of sensitization and annealing on the photovoltaic performance of the solar cells fabricated using four different photoelectrodes was studied using the photocurrent density versus photovoltage curves. Annealing apparently improved the photovoltaic performance of photoanodes. The best performance was obtained for cell fabricated using annealed TiO2/Bi2S3 photoanode after 30 min sensitization time showing V oc ~ 0.37 mV, J sc ~ 0.52 mA/cm2, FF ~ 68 and 0.43 %.

  14. Enhanced Luminescence of Eu-Doped TiO2Nanodots

    PubMed Central

    2009-01-01

    Monodisperse and spherical Eu-doped TiO2nanodots were prepared on substrate by phase-separation-induced self-assembly. The average diameters of the nanodots can be 50 and 70 nm by changing the preparation condition. The calcined nanodots consist of an amorphous TiO2matrix with Eu3+ions highly dispersed in it. The Eu-doped TiO2nanodots exhibit intense luminescence due to effective energy transfer from amorphous TiO2matrix to Eu3+ions. The luminescence intensity is about 12.5 times of that of Eu-doped TiO2film and the luminescence lifetime can be as long as 960 μs. PMID:20596343

  15. 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. PMID:25852353

  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. Nb doping effect on TiO2-x films for bolometer applications

    NASA Astrophysics Data System (ADS)

    Shin, Young Bong; Kumar Reddy, Y. Ashok; Kang, In-Ku; Lee, Hee Chul

    2016-04-01

    Nb-doped TiO2-x thin films were deposited using a 1 at% niobium doped titanium target by RF reactive magnetron sputtering at various oxygen partial pressures (pO2). The films appeared amorphous in the pO2 range of 4.4-4.7% with resistivity ranging from 0.39 Ω cm to 2.48 Ω cm. Compared to pure TiO2-x films, the resistivity of the Nb-doped TiO2-x films did not change sensitively with the oxygen partial pressure, indicating that the resistivity of the films can be accurately controlled. 1/f noise parameter of Nb-doped TiO2-x films were found to decrease largely while the measured temperature coefficient of resistance (TCR) of the films was still high. The obtained results indicate that Nb-doped TiO2-x films have great potential as an alternative bolometric material.

  18. Effect of Xe ion irradiation on photocatalytic performance of oblique TiO2 nanowire arrays

    NASA Astrophysics Data System (ADS)

    Li, Zhengcao; Teng, Yi; Chen, Chienhua; Lv, Shasha; Wang, Guojing; Zhang, Zhengjun

    2015-02-01

    In this work oblique TiO2 nanowire arrays (NWs) were prepared by magnetron sputtering method and irradiated by 200 keV Xe ion with different doses. The photocatalytic activity of TiO2 was studied by degrading methyl orange dye (MO) under ultraviolet (UV) light, which indicates that the photocatalytic performance of as-deposited and irradiated TiO2 NWs. It was found that when the dose was relatively low, the Ti3+ content on the surface was increased upon irradiation, dominating the enhancement of the photocatalytic property of the TiO2 NWs. By this means, an optimization of Xe ion dose can largely improve the photocatalytic performance of TiO2 NWs.

  19. Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.

    PubMed

    Wang, Hairong; Sun, Quantao; Chen, Lei; Zhao, Yulong

    2013-09-01

    In this paper, we investigated the sensing properties of sandwich structure of TiO2/Pd/TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2/Pd/TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2/Pd/TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240 °C. PMID:24089853

  20. 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.

  1. Photoconductivity studies on amorphous and crystalline TiO2 films doped with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Valverde-Aguilar, G.; García-Macedo, J. A.; Rentería-Tapia, V.; Aguilar-Franco, M.

    2011-06-01

    In this work, amorphous and crystalline TiO2 films were synthesized by the sol-gel process at room temperature. The TiO2 films were doped with gold nanoparticles. The films were spin-coated on glass wafers. The crystalline samples were annealed at 100°C for 30 minutes and sintered at 520°C for 2 h. All films were characterized using X-ray diffraction, transmission electronic microscopy and UV-Vis absorption spectroscopy. Two crystalline phases, anatase and rutile, were formed in the matrix TiO2 and TiO2/Au. An absorption peak was located at 570 nm (amorphous) and 645 nm (anatase). Photoconductivity studies were performed on these films. The experimental data were fitted with straight lines at darkness and under illumination at 515 nm and 645 nm. This indicates an ohmic behavior. Crystalline TiO2/Au films are more photoconductive than the amorphous ones.

  2. Effects of annealed temperature on the properties of TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Kumar, Avesh

    2016-05-01

    In this work, the structural, morphological and electrical properties of TiO2 thin films are studied. The phase transformation of TiO2 from anatase to rutile is occurred at a certain temperature. This transformation increases defects concentration onthe surface of the film which acts as trapping sites for carriers, thereby affecting the Fermi level of TiO2 film.Quantitative estimation of Fermi level shifting is measured in terms of work function measurement using scanning Kelvin probe measurement. Work function of TiO2 was found to decrease with increasing annealed temperature indicating shifting of Fermi level towards conduction band. Position of Fermi level plays an important role in phase transformation and electronic properties of TiO2.

  3. Characterization and acetone gas sensing properties of electrospun TiO2 nanorods

    NASA Astrophysics Data System (ADS)

    Bian, Haiqin; Ma, Shuyi; Sun, Aimin; Xu, Xiaoli; Yang, Guijin; Gao, Jiming; Zhang, Zhengmei; Zhu, Haibin

    2015-05-01

    In this work, random network structure of titanium dioxides (TiO2) nanorods was synthesized by calcining electrospun TiO2/PVP hybrid rods. Structural, optical and acetone gas sensing properties of the nanorods were investigated. The TiO2 nanorods are polycrystalline with a mixture of anatase and rutile structures. The diameter of TiO2 nanorods is about 500 nm. The photoluminescence (PL) spectra measurement at room temperature revealed that a broad emission band including the two emission peaks are about at 401 and 467 nm. The sensor shows the high response, good reproducibility and selectivity for acetone (CH3COCH) with a fast response and recovery time at 500 °C. In addition, the acetone sensing mechanism of the TiO2 nanorods sensors is discussed.

  4. Synthesis of anatase and rutile TiO2 nanostructures from natural ilmenite

    NASA Astrophysics Data System (ADS)

    Wahyuingsih, Sayekti; Ramelan, Ari Handono; Pramono, Edi; Sulistya, Ariantama Djati; Argawan, Panji Rofa; Dharmawan, Frenandha Dwi; Rinawati, Ludfiaastu; Hanif, Qonita Awliya; Sulistiyono, Eko; Firdiyono, Florentinus

    2016-02-01

    Nanostructure anatase and rutile type TiO2 were synthesized from dissolution roasted ilmenite from natural ilmenite sand as the starting materials. Anatase TiO2 and rutile TiO2 (high crystallinity) with the diameters of 20-100 nm were obtained by calcined soluble ilmenite sand produced by leaching process. Calcinations of the xerogel TiO2 from liquor products were conducted for 4 hours at temperature of 450 °C. The samples were characterized by XRD (X-ray diffraction), STA (simultant thermal analysis), TEM (Transmission Electron Microscopy), and BET surface area. Titania Anatase-Rutile form as a mixture were produced by titania slag with the hydrolysis product. While, in another route, complete titania anatase phase was produced through hydrolysis and condensation steps of leach liquors. This synthesis methods provide a simple route to fabricate nanostructure TiO2 from low cost material.

  5. Effect of Porosity on Photocatalytic Activity of Plasma-Sprayed TiO2 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Chaudhary, Ujwal; Das, Santanu; Godavarty, Anuradha; Agarwal, Arvind

    2013-10-01

    The effect of porosity on photocatalytic activity of plasma-sprayed TiO2 coating on steel substrate is studied by varying processing parameters viz. plasma power and powder feed rate. The relationship between porosity content and methylene blue (MB) dye decomposition rate was established to correlate coating microstructure and its photocatalytic activity. The coating with the highest porosity content exhibited best photocatalytic efficiency. The same processing parameters were used to deposit TiO2 coating on FTO glass. The photocatalytic activity of TiO2 coating on FTO was 2.5 times better than TiO2 coating on the steel substrate. TiO2 coating on FTO glass contains bimodal porosity distribution (micropores and submicron pores) which accelerated MB decomposition by accelerated diffusion of ionic species.

  6. 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.

  7. 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.

  8. Synthesis of hierarchical TiO2 nanowires with densely-packed and omnidirectional branches

    NASA Astrophysics Data System (ADS)

    Lee, Daeho; Rho, Yoonsoo; Allen, Frances I.; Minor, Andrew M.; Ko, Seung Hwan; Grigoropoulos, Costas P.

    2013-10-01

    In this study, a hierarchical TiO2 nanostructure with densely-packed and omnidirectional branches grown by a hydrothermal method is introduced. This morphology is achieved via high-concentration TiCl4 treatment of upright backbone nanowires (NWs) followed by hydrothermal growth. Secondary nanobranches grow in all directions from densely distributed, needle-like seeds on the jagged round surface of the backbone NWs. In addition, hierarchical, flower-like branches grow on the top surface of each NW, greatly increasing the surface area. For dye-sensitized solar cell (DSSC) applications, the TiO2 nanostructure demonstrated a photoconversion efficiency of up to 6.2%. A parametric study of the DSSC efficiency showed that branched TiO2 DSSCs can achieve nearly four times the efficiency of non-branched TiO2 nanowire DSSCs, and up to 170% the efficiency of previously-reported sparsely-branched TiO2 NW DSSCs.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Removal of benzene and toluene by carbonized bamboo materials modified with TiO2.

    PubMed

    Chuang, Chih Shen; Wang, Ming-Kuang; Ko, Chun-Han; Ou, Chia-Chih; Wu, Chien-Hou

    2008-03-01

    Carbonized moso bamboo (Phyllostachys pubescens) was coated with TiO(2) nanoparticles to enhance its removal efficiency of harmful gases. Carbonized bamboo-TiO(2) composite (CBC) was prepared by heating mixtures of carbonized bamboo powder (CB) and TiO(2) nanoparticles, denoted as CBM, under nitrogen condition. TiO(2) nanoparticle and carbonized bamboo powder were mixed with the mass ratios of 1/1 and 2/1, respectively. At the same mass ratio of TiO(2) to CB, the benzene and toluene removal efficiencies follow the trend: CBC>CBM>CB, which is consistent with the amount of TiO(2) validated by elemental analysis. Sorption mechanism of benzene and toluene by CB, CBM and CBC might belong to hydrophobic-hydrophobic interaction, observed by depletion of untreated bamboo (UB) carbohydrates during carbonization. Sorption kinetics was further analyzed, and optimal correlation was found by fitting with the Elovich kinetic equation. PMID:17459699

  14. Photocatalytic oxidation of chloroform using immobilized-biogenic TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Cho, Y.; Yoo, H.

    2011-12-01

    Although commercial titanium dioxide (TiO2) nanoparticles as a suspension in water are one of the most popular photocatalysts for treatment of chlorinated organic compounds, the reuse and recovery of the nanoscale phtocatalyst is a practical challenge for application in water and groundwater treatment system. As part of efforts to overcome this practical limitation, development of immobilized TiO2 is needed. Diatom Pinnularia sp. were found to be capable of producing nanoscale TiO2 in their microscale silica shells. In order to obtain biogenic TiO2 nanoparticles from Pinnularia sp., soluble Ti was fed to the silicon-starved cells, resulting in deposition of titanium on the microscale features of the silica shells. After thermal treatment at 720 oC for 2 hr, the titanium was eventually converted to nanoscale TiO2. In order to determine the physical and chemical properties of the immobilized TiO2, material characterization such as TEM, STEM-EDS, BET and XRD analysis was carried out. In this study, a novel type of immobilized photocatalytic nanoparticles, biogenic TiO2 on silica shells was used for the mineralization of chloroform in water. Batch tests were conducted to evaluate the chloroform removal efficiency of biogenic and commercial TiO2 nanoparticles. Also, the amount of Cl- ions in water during the mineralization was measured to check mineralization of chloroform by biogenic TiO2 nanoparticles. Kinetic models were used to determine the rate of chloroform mineralization. In addition, the effect of UVA (ultraviolet-A) intensity on chloroform mineralization was investigated. The results obtained from this study could provide useful information for practical application of biogenic TiO2 in the groundwater treatment contaminated with some chlorinated organic compounds.

  15. Achieving enhanced DSSC performance by microwave plasma incorporation of carbon into TiO2 photoelectrodes

    NASA Astrophysics Data System (ADS)

    Dang, Binh H. Q.; MacElroy, Don; Dowling, Denis P.

    2013-06-01

    The photoactivity of carbon-incorporated titanium dioxide (TiO2) has been widely reported. This study involves a novel approach to the incorporation of carbon into TiO2 through the use of microwave plasma processing. The process involved thermally treating printed TiO2 nanoparticle coatings in a microwave-induced argon-oxygen plasma containing low concentrations of methane. The resulting deposited carbon layer was characterized using XRD, XPS, Raman, UV-vis, ellipsometry, and optical profilometry. It was found that the methane gas was dissociated in the microwave plasma into its carbon species, which were then deposited as a nm-thick layer onto the TiO2 coatings, most likely in the form of graphite. The photovoltaic performances of both the TiO2 and the carbon-incorporated TiO2 were assessed through J-V and IPCE measurements of the N719-sensitized solar cells using the titania as their photoanodes. Up to a 72% improvement in the maximum power density (Pd-max) was observed for the carbon-incorporated TiO2 samples as compared to the TiO2, onto which no carbon was added. This improvement was found to be mainly associated with an increase in the short-circuit current density (Jsc), but independent from the open-circuit voltage (Voc), the filter factor (FF), and the level of dye adsorption. Possible contributory factors to the improved performance of the carbon-incorporated TiO2 were the enhanced electron conductivity and electron lifetime, both of which were elucidated through electrochemical impedance spectroscopy (EIS). When the surface layer was examined using XPS, the optimal carbon content on the TiO2 coating surface was found to be 8.4%, beyond which there was a reduction in the DSSC efficiency.

  16. 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.

  17. 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

  18. High photocatalytic activity of immobilized TiO2 nanorods on carbonized cotton fibers.

    PubMed

    Wang, Bin; Karthikeyan, Rengasamy; Lu, Xiao-Ying; Xuan, Jin; Leung, Michael K H

    2013-12-15

    In this study, TiO2 nanorods were successfully immobilized on carbon fibers by a facile pyrolysis of natural cotton in nitrogen atmosphere followed by a one-pot hydrothermal method. Carbonized cotton fibers (CCFs) and TiO2-CCFs composites were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffractometer (XRD), diffuse reflectance UV-vis spectroscopy (DRS) and photoluminescence (PL) spectroscopy. Results implied that the band gap narrowing of TiO2 was achieved after integration of CCFs. Dye adsorption isotherm indicated that the maximum dye adsorption capacity (qm) of CCFs-1000 (13.4 mg/g) was 2 times higher than that of cotton fibers and qm of TiO2-CCFs-1000 (9.0mg/g) was 6-7 times higher than that of TiO2 nanorods. Photocatalytic activity of TiO2 nanorods prepared with 3 mL Ti(OBu)4 showed the highest photocatalytic activity. TiO2-CCFs-1000 exhibited higher activity than TiO2 immobilized on CCFs-400, CCFs-600 and CCFs-800. Good photostability of TiO2-CCFs-1000 was found for dye degradation under visible light irradiation. The enhancement of photocatalytic dye degradation was due to the high adsorptivity of dye molecules, enhanced light adsorption and effective separation of electron-hole pairs. This work provides a low-cost and sustainable approach to immobilize nanostructured TiO2 on carbon fibers for environmental remediation. PMID:24220193

  19. Interface actions between TiO2 and porous diatomite on the structure and photocatalytic activity of TiO2-diatomite

    NASA Astrophysics Data System (ADS)

    Xia, Yue; Li, Fangfei; Jiang, Yinshan; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-06-01

    TiO2-diatomite photocatalysts were prepared by sol-gel process with various pre-modified diatomite. In order to obtain diatomite with different surface characteristics, two modification approaches including calcination and phosphoric acid treatment on the micro-structure of diatomite are introduced. The photocatalysts were characterized by XRD, XPS, nitrogen adsorption-desorption isotherms and micromorphology analysis. The results indicate that, compared with pure TiO2, the anatase-to-rutile phase transition temperature of TiO2 loaded on diatomite carrier is significantly increased to nearly 900 °C, depending on the different pretreatment method of diatomite. The photocatalytic activities of different samples were evaluated by their degradation rate of methyl orange (MO) dye under UV and visible-light irradiation. The samples prepared by phosphoric acid pretreatment method exhibit the highest photocatalytic activity. After 90 min of UV irradiation, about 90% of MO is decomposed by the best effective photocatalyst. And after 8 h visible-light irradiation, nearly 60% of MO is decomposed by the same sample. Further mechanism investigation reveals that the H3PO4 pretreatment process can obviously change the surface features of diatomite carrier, cause the formation of Si-O-Ti bond, increase the binding strength between TiO2 and diatomite, restrain crystal growth of loaded TiO2, and thus form thermal-stable mesoporous structure at the granular spaces. It helps to build micro-, meso- and macro-porous hierarchical porous structure in TiO2-diatomite, and improves the charge and mass transfer efficiency during catalyzing process, resulting in the significantly increased photocatalytic activity of TiO2-diatomite pretreated by phosphoric acid.

  20. 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.

  1. 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

  2. Self-cleaning properties of cement plates loaded with N,C-modified TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Janus, Magdalena; Zatorska, Justyna; Czyżewski, Adam; Bubacz, Kamila; Kusiak-Nejman, Ewelina; Morawski, Antoni W.

    2015-03-01

    The photocatalytic activity of cement pastes containing nitrogen and carbon co-modified TiO2 photocatalysts (TiO2-N,C) were evaluated trough the degradation of model organic water contaminate (Reactive Red 198) under UV-vis light source. It was found that cement plates containing TiO2-N,C photocatalysts exhibited higher photocatalytic efficiency than those containing unmodified TiO2.

  3. New evidence for TiO2 uniform surfaces leading to complete bacterial reduction in the dark: critical issues.

    PubMed

    Nesic, Jelena; Rtimi, Sami; Laub, Danièle; Roglic, Goran M; Pulgarin, Cesar; Kiwi, John

    2014-11-01

    This study presents new evidence for the events leading to Escherichia coli reduction in the absence of light irradiation on TiO2-polyester (from now on TiO2-PES. By transmission electron microscopy (TEM) the diffusion of TiO2 NP's aggregates with the E. coli outer lipo-polyssacharide (LPS) layer is shown to be a prerequisite for the loss of bacterial cultivability. Within 30 min in the dark the TiO2 aggregates interact with E. coli cell wall leading within 120 min to the complete loss of bacterial cultivability on a TiO2-PES 5% TiO2 sample. The bacterial reduction was observed to increase with a higher TiO2 loading on the PES up to 5%. Bacterial disinfection on TiO2-PES in the dark was slower compared to the runs under low intensity simulated sunlight light irradiation. The interaction between the TiO2 aggregates and the E. coli cell wall is discussed in terms of the competition between the TiO2 units collapsing to form TiO2-aggregates at a physiologic pH-value followed by the electrostatic interaction with the bacteria surface. TiO2-PES samples were able to carry repetitive bacterial inactivation. This presents a potential for practical applications. X-ray photoelectron spectroscopy (XPS) evidence was found for the reduction of Ti4+ to Ti3+ contributing to redox interactions between TiO2-PES and the bacterial cell wall. Insight is provided into the mechanism of interaction between the E. coli cell wall and TiO2 NP's. The properties of the TiO2-PES surface like percentage atomic concentration, TiO2-loading, optical absorption, surface charge and crystallographic phases are reported in this study. PMID:25444660

  4. 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.

  5. TiO2-graphene nanocomposites for enhanced osteocalcin induction.

    PubMed

    Kandiah, Kavitha; Muthusamy, Prabhu; Mohan, Selvam; Venkatachalam, Rajendran

    2014-05-01

    Bone defects and damages are common these days, which increases the usage of biomaterial for humans. To prepare a potential biomaterial, we synthesised a series of titania-graphene nanocomposites (TGS) (2:x (0.25, 0.5, 1.0, 2.0, and 4.0 g)) using in situ sol-gel method. The obtained structural results show that the prepared TGS nanocomposites are an irregular sheet with spherical TiO2 intercalated morphology. The SSA of the nanocomposites ranging from 167.98 to 234.56 m(2) g(-1) with mesoporosity and swelling tendency ranging from 11.55 to 26.13% leads to an enhancement in human cell attachment as well as avoids the migration and agglomeration of the nanoparticles in the body. Further, the biological analysis in simulated body fluid and human cell lines (AGS and MG-63) collectively reveals that the TG2 (2:2) and TG4 (2:4) samples are found to be more favourable materials for biomimic bone action among the prepared TGS nanocomposites. PMID:24656376

  6. The potential health challenges of TiO2 nanomaterials.

    PubMed

    Sha, Baoyong; Gao, Wei; Cui, Xingye; Wang, Lin; Xu, Feng

    2015-10-01

    Titanium dioxide (TiO2 ) nanomaterials (NMs) have found widespread applications owing to their attractive physical and chemical properties. As a result, the potential adverse impacts of nano-TiO2 exposure on humans have become a matter of concern. This review presents the state-of-the-art advances on the investigations of the adverse effects of NMs, including the potential exposure routes of nano-TiO2 (e.g. respiratory system, skin absorption and digestive system), the physico-chemical characterizations of nano-TiO2 (e.g. crystal structure, shape,size, zeta potential, treatment media, aggregation and agglomeration tendency, surface characteristics and coatings), risk evaluation of nanotoxicity (e.g. cytotoxicity, ecotoxicity, phototoxicity, and phytotoxicity) and potential mechanisms of adverse effects (e.g. generation of reactive oxygen species, oxidative stress and organelle dysfunction). The review aims to facilitate scientific assessments of health risks to nano-TiO2 , which would guide the safe applications of NMs in our daily life. PMID:26179748

  7. 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.

  8. Crystallinity of anodic TiO2 nanotubes and bioactivity.

    PubMed

    An, Sang-Hyun; Narayanan, Ramaswamy; Matsumoto, Takuya; Lee, Hyo-Jin; Kwon, Tae-Yub; Kim, Kyo-Han

    2011-06-01

    Anodic TiO2 nanotubes were produced on titanium at 20 V using 1 M Na2SO4 and 0.5 wt% NaF. Oxidation for 3 hours produced amorphous tubes of diameter 100 nm and thicknesses 2 microm. Heat-treatments were done for 3 hours at different temperatures. 300 degrees C treatment converted the amorphous coatings to anatase. 550 and 700 degrees C treatments formed dual anatase and rutile; 850 degrees C treatment crystallized to rutile. The treatment at 700 degrees C produced an oxide surface with higher roughness, lower wetting angle and higher coating adhesion. Bioactivity of the as-oxidized and heated coatings were evaluated by treating them in a simulated body fluid (SBF) to form hydroxyapatite (HA) and the rates of HA formation were compared. Deposits of HA could be seen on the dual oxide structure within 3 days. HA was detected after 7 days in the anatase structure and only after 21 days in the amorphous and rutile structures. In vitro cell culture tests done using mouse osteoblasts indicated that, the 700 degrees C-heated surface showed higher levels of cell activity than the other surfaces. It is concluded that the dual rutile and anatase structure formed by heating the oxide at 700 degrees C is the best of the five surfaces tested. PMID:21770121

  9. Quantum Dot TiO2-Ge Solar Cells

    NASA Astrophysics Data System (ADS)

    Church, Carena; Muthuswamy, Elayaraja; Kauzlarich, Susan; Carter, Sue

    2014-03-01

    Colloidal germanium (Ge) quantum dots (CQDs) are attractive solar materials due to their low toxicity compared to Pb- or Cd- based nanocrystals (NC), low cost, and optimal, tunable bandgap for both increased IR response and potential power conversion efficiency (η) boosts from Multiple Exciton Generation (MEG). We report on the successful fabrication and characterization of spun-cast donor/acceptor type TiO2-Ge CQD solar cells utilizing Ge colloidal quantum dots (CQD) synthesized via a facile microwave method as the active layer. We find that our Ge QD size performance-related trends are similar to other QD systems studied. Additionally, our best heterojunction devices achieved short circuit currents (JSC) of 450 μA and open circuit voltages (VOC) of 0.335 V, resulting in η = 0.022 %. While this represents significant increases over previous Ge CQD PV (85 % over hybrid Ge-P3HT PV, 350 % over Ge NC PV), our photocurrents are still much lower than other NC systems. Analysis of intensity-dependent J-V characteristics reveal that our currents are limited by a space-charge region that forms leading to unbalanced charge extraction. We conclude by discussing a variety of film treatments and device structures we have tested to increase JSC.

  10. Adsorption and solar light decomposition of acetone on anatase TiO2 and niobium doped TiO2 thin films.

    PubMed

    Mattsson, Andreas; Leideborg, Michael; Larsson, Karin; Westin, Gunnar; Osterlund, Lars

    2006-01-26

    Adsorption and solar light decomposition of acetone was studied on nanostructured anatase TiO2 and Nb-doped TiO2 films made by sol-gel methods (10 and 20 mol % NbO2.5). A detailed characterization of the film materials show that films contain only nanoparticles with the anatase modification with pentavalent Nb oxide dissolved into the anatase structure, which is interpreted as formation of substituted Nb=O clusters in the anatase lattice. The Nb-doped films displayed a slight yellow color and an enhanced the visible light absorption with a red-shift of the optical absorption edge from 394 nm for the pure TiO2 film to 411 nm for 20 mol % NbO2.5. In-situ Fourier transform infrared (FTIR) transmission spectroscopy shows that acetone adsorbs associatively with eta1-coordination to the surface cations on all films. On Nb-doped TiO2 films, the carbonyl bonding to the surface is stabilized, which is evidenced by a lowering of the nu(C=O) frequency by about 20 cm(-1) to 1672 cm(-1). Upon solar light illumination acetone is readily decomposed on TiO2, and stable surface coordinated intermediates are formed. The decomposition rate is an order of magnitude smaller on the Nb-doped films despite an enhanced visible light absorption in these materials. The quantum yield is determined to be 0.053, 0.004 and 0.002 for the pure, 10% Nb:TiO2, and 20%Nb:TiO2, respectively. Using an interplay between FTIR and DFT calculations we show that the key surface intermediates are bidentate bridged formate and carbonate, and H-bonded bicarbonate, respectively, whose concentration on the surface can be correlated with their heats of formation and bond strength to coordinatively unsaturated surface Ti and Nb atoms at the surface. The oxidation rate of these intermediates is substantially slower than the initial acetone decomposition rate, and limits the total oxidation rate at t>7 min on TiO2, while no decrease of the rate is observed on the Nb-doped films. The rate of degradation of key surface intermediates is different on pure TiO2 and Nb-doped TiO2, but cannot explain the overall lower total oxidation rate for the Nb-doped films. Instead the inferior photocatalytic activity in Nb-doped TiO2 is attributed to an enhanced electron-hole pair recombination rate due to Nb=O cluster and cation vacancy formation. PMID:16471666

  11. Natural dye sensitized TiO2 nanorods assembly of broccoli shape based solar cells.

    PubMed

    Yuvapragasam, Akila; Muthukumarasamy, N; Agilan, S; Velauthapillai, Dhayalan; Senthil, T S; Sundaram, Senthilarasu

    2015-07-01

    TiO2 nanorods based thin films with rutile phase have been synthesized using template free low temperature hydrothermal method. The scanning electron microscope images showed that the prepared TiO2 samples were made of TiO2 nanorods and the nanorods had arranged by itself to form a broccoli like shape. The X-ray diffraction studies revealed that the prepared TiO2 samples exhibit rutile phase. The grown TiO2 nanorods had been sensitized using the flowers of Sesbania (S) grandiflora, leaves of Camellia (C) sinensis and roots of Rubia (R) tinctorum. Dye sensitized solar cells had been fabricated using the natural dye sensitized TiO2 nanorods based thin film photoelectrode and the open circuit voltage and short circuit current density were found to lie in the range of 0.45-0.6 V and 5.6-6.4 mA/cm(2) respectively. The photovoltaic performance of all the fabricated natural dye sensitized TiO2 solar cells indicate that natural dyes have the potential to be used as effective sensitizer in dye sensitized solar cells. PMID:25974906

  12. Noble metal nanoparticle-decorated TiO2 nanobelts for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    He, Haiyan; Yang, Ping; Jia, Changchao; Miao, Yanping; Zhao, Jie; Du, Yingying

    2014-07-01

    TiO2 nanobelts have been fabricated through a hydrothermal method and subsequently sulfuric-acid-corrosion-treated for a rough surface. Noble metal nanoparticles such as Ag and Au were deposited on the coarse surface of TiO2 nanobelts via a coprecipitation procedure. Ag-TiO2 nanobelts were prepared in ethanolic solution contained silver nitrate (AgNO3) and sodium hydroxide (NaOH). Au-TiO2 nanobelts were obtained in chloroauric acid (HAuCl4) using sodium borohydride (NaBH4) as the reductant. It is confirmed by the results of XRD patterns together with the SEM images that the composite of noble metal and TiO2 nanobelts were obtained successfully and the Ag or Au nanoparticles were well-dispersed on the TiO2 nanobelts. Moreover, the as-prepared Ag and Au nanoparticle-decorated TiO2 nanobelts represent an enhanced photocatalytic activity compared with pure TiO2 nanobelts, which is due to the fact that the Ag and Au nanoparticles on the surface of TiO2 nanobelts act as sinks for the photogenerated electrons and promote the separation of the electrons and holes.

  13. Preparation and photocatalytic activity of CeO 2/TiO 2 interface composite film

    NASA Astrophysics Data System (ADS)

    Jiang, Bangtong; Zhang, Shengyi; Guo, Xiaozhu; Jin, Baokang; Tian, Yupeng

    2009-03-01

    The CeO 2/TiO 2 and TiO 2/CeO 2 interface composite films were prepared on glass substrates by the sol-gel process via dip-coating and calcining technique. The scanning electron microscopy (SEM) revealed that the TiO 2 layer has a compact and uniformity glasslike surface with 200 nm in thickness, and the CeO 2 layer has a coarse surface with 240 nm in thickness. The X-ray diffractometer (XRD) analysis showed that the TiO 2 layer is made up of anatase phase, and the CeO 2 layer is structured by cubic fluorite phase. Through a series of photo-degradation experiments, the relationship of the photocatalytic activity with the constituents of the films was studied. In virtue of the efficient interfacial charge separation via the process of electron transfer from TiO 2 to CeO 2, the photocatalytic activity of the CeO 2/TiO 2 composite film is high. Contrarily, the photocatalytic activity of the TiO 2/CeO 2 composite film is low, due to its inert surface made up of CeO 2 with broad bandwidth. Apart from the effect of the film structure, the effect of film thickness on photocatalytic activity was also discussed.

  14. Thermal evolution of structure and photocatalytic activity in polymer microsphere templated TiO2 microbowls

    NASA Astrophysics Data System (ADS)

    Erdogan, Deniz Altunoz; Polat, Meryem; Garifullin, Ruslan; Guler, Mustafa O.; Ozensoy, Emrah

    2014-07-01

    Polystyrene cross-linked divinyl benzene (PS-co-DVB) microspheres were used as an organic template in order to synthesize photocatalytic TiO2 microspheres and microbowls. Photocatalytic activity of the microbowl surfaces were demonstrated both in the gas phase via photocatalytic NO(g) oxidation by O2(g) as well as in the liquid phase via Rhodamine B degradation. Thermal degradation mechanism of the polymer template and its direct influence on the TiO2 crystal structure, surface morphology, composition, specific surface area and the gas/liquid phase photocatalytic activity data were discussed in detail. With increasing calcination temperatures, spherical polymer template first undergoes a glass transition, covering the TiO2 film, followed by the complete decomposition of the organic template to yield TiO2 exposed microbowl structures. TiO2 microbowl systems calcined at 600 °C yielded the highest per-site basis photocatalytic activity. Crystallographic and electronic properties of the TiO2 microsphere surfaces as well as their surface area play a crucial role in their ultimate photocatalytic activity. It was demonstrated that the polymer microsphere templated TiO2 photocatalysts presented in the current work offer a promising and a versatile synthetic platform for photocatalytic DeNOx applications for air purification technologies.

  15. The behaviors of anatase and TiO2(B) phase coexisting nanosheets under high pressure

    NASA Astrophysics Data System (ADS)

    Huang, Yanwei; Li, Wentao; Ren, Xiangting; Yu, Zhenhai; Samanta, Sudeshna; Yan, Shuai; Zhang, Jun; Wang, Lin

    2016-03-01

    High pressure behaviors of anatase TiO2 and TiO2(B) coexisting nanosheets were investigated using in situ synchrotron X-ray diffraction and Raman Spectroscopy. The X-ray diffraction revealed that upon compression an α-PbO2 phase appeared at 11.4 GPa, and then the baddeleyite phase appeared at 23.6 GPa. Upon decompression the anatase phase still existed obviously and TiO2(B) phase almost cannot be observed. The Raman spectrum at ambient pressure presented the typical curve of anatase TiO2, however the pressure dependence for compression and decompression did not show the common phase transion from anatase to α-PbO2 or to baddeleyite. This is different from high pressure behaviors of other TiO2 nanostructures and could be attributed to the existence of small amount of TiO2(B) at the starting materials. The pressure relationship of the Raman frequencies shift slope indicated the coexistence nanosheet has high incompressibility compared with other TiO2 nanomaterials and corresponding bulks.

  16. Phase dependent photocatalytic activity of Ag loaded TiO2 films under sun light

    NASA Astrophysics Data System (ADS)

    Madhavi, V.; Kondaiah, P.; Shaik, Habibuddin; Rao, G. Mohan

    2016-02-01

    Well-crystallized anatase and mixed (anatase-rutile) phase TiO2 thin films were deposited by DC magnetron sputtering technique at various DC powers in the range of 80-140 W. Pure anatase phase was observed in the TiO2 films deposited at low power of 80 W. Films deposited at 120 W were composed of both anatase and rutile phases. At higher power of 140 W, the films are rutile dominated and the rutile percentage increased from 0 to 82% with increase of DC power. The same results of phase change were confirmed by Raman studies. The surface morphology of the TiO2 films showed that the density of the films increased with increase of sputter power. The optical band gap of the films varied from 3.35 to 3.14 eV with increase of DC power. The photocatalytic activity of the TiO2 films increased with increasing DC power up to 120 W and after that it decreases. We found that the TiO2 films deposited at 120 W with 48% of rutile phase, exhibited high photocatalytic activity (43% of degradation) under UV light compared with other TiO2 films. After loading the optimized Ag nanoparticles on the mixed phase TiO2 films, the photocatalytic activity shifted from UV to visible region with enhancement of photocatalytic activity (55% of degradation).

  17. Density functional theory study of dopants in polycrystalline TiO2

    NASA Astrophysics Data System (ADS)

    Körner, Wolfgang; Elsässer, Christian

    2011-05-01

    We present a density functional theory (DFT) study of doped rutile and anatase TiO2 in which we investigate the impact of grain boundaries on the physics of atomic defects. The main goal is to obtain information about the positions of the defect levels generated by an oxygen vacancy, a titanium interstitial, cation dopants Nb, Al, and Ga, and an anion dopant N in the electronic band gap having in mind the application of TiO2 as a transparent conducting oxide (TCO) or its use in heterogeneous catalysis. Due to the known deficiency of the local density approximation (LDA) of DFT to yield accurate values for band gap energies for insulators such as TiO2, a self-interaction correction (SIC) to the LDA is employed. The main result of our study is that grain boundaries do affect the defect formation energies as well as the position and shape of the dopant-induced electronic energy levels significantly with respect to the single crystal. According to our study Nb doping may lead to n-conducting TiO2 whereas doping with N, Al, or Ga is not promising in order to achieve p-conducting TiO2. Furthermore an increase in the photoconductivity of TiO2:N and the colorlessness of TiO2:Al may be explained by our results.

  18. 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

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

    PubMed

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

    2016-01-01

    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. PMID:26840294

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. Preparation of mesoporous nanocrystalline anatase TiO2 for dye sensitized solar cell application

    NASA Astrophysics Data System (ADS)

    Jacob, K. Stanly; Abraham, P. A.; Panicker, N. Rani; Pramanik, N. C.

    2014-01-01

    Dye sensitized solar cell (DSSC) introduced by Prof.M.Gratzel is a low cost alternative to the existing silicon based solar cells. Solar light conversion efficiency of the current DSSC can be further improved by replacing the conventional anatase TiO2 having lesser surface area with mesoporous high surface area anatase TiO2. This paper describes the sol-gel synthesis of mesoporous high surface area nanocrystalline anatase TiO2 by the controlled hydrolysis and condensation of titanium isopropoxide followed by heat treatment. XRD reveals that xerogel heat treated at 500°C is phase pure anatase. Crystallite size of prepared anatase TiO2 calculated using Scherrer equation was found to be 15 nm. BET analysis of prepared anatase TiO2 exhibited relatively high specific surface area of 97 m2/g, which is found to be almost double to that of the anatase TiO2 generally used for DSSC photo anode fabrication. The pore size distribution (BJH plot) also revealed the mesoporous nature of prepared anatase TiO2 having an average pore size of 7.4 nm.

  5. 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

  6. Carbon functionalized TiO2 nanofibers for high efficiency photocatalysis

    NASA Astrophysics Data System (ADS)

    Raghava Reddy, Kakarla; Gomes, Vincent G.; Hassan, Mahbub

    2014-03-01

    TiO2 nanofibers (30-50 nm diameter), fabricated by the electro-spinning process, were modified with organo-silane agents via a coupling reaction and were grafted with carbohydrate molecules. The mixture was carbonized to produce a uniform coating of amorphous carbon on the surface of the TiO2 nanofibers. The TiO2@C nanofibers were characterized by high resolution electron microscopy (HRTEM), x-ray diffraction (XRD), x-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-vis spectroscopy. The photocatalytic property of the functional TiO2 and carbon nanocomposite was tested via the decomposition of an organic pollutant. The catalytic activity of the covalently functionalized nanocomposite was found to be significantly enhanced in comparison to unfunctionalized composite and pristine TiO2 due to the synergistic effect of nanostructured TiO2 and amorphous carbon bound via covalent bonds. The improvement in performance is due to bandgap modification in the 1D co-axial nanostructure where the anatase phase is bound by nano-carbon, providing a large surface to volume ratio within a confined space. The superior photocatalytic performance and recyclability of 1D TiO2@C nanofiber composites for water purification were established through dye degradation experiments.

  7. 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.

  8. 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

  9. 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.

  10. Light-induced antifungal activity of TiO 2 nanoparticles/ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Haghighi, N.; Abdi, Y.; Haghighi, F.

    2011-09-01

    Antifungal activity of TiO2/ZnO nanostructures under visible light irradiation was investigated. A simple chemical method was used to synthesize ZnO nanowires. Zinc acetate dihydrate, Polyvinyl Pyrrolidone and deionized water were used as precursor, capping and solvent, respectively. TiO2 nanoparticles were deposited on ZnO nanowires using an atmospheric pressure chemical vapor deposition system. X-ray diffraction pattern of TiO2/ZnO nano-composite has represented the diffraction peaks relating to the crystal planes of the TiO2 (anatase and rutile) and ZnO. TiO2/ZnO nanostructure antifungal effect on Candida albicans biofilms was studied and compared with the activity of TiO2 nanoparticles and ZnO nanowires. The high efficiency photocatalytic activity of TiO2 nanoparticles leads to increased antifungal activity of ZnO nanowires. Scanning electron microscope was utilized to study the morphology of the as prepared nanostructures and the degradation of the yeast.

  11. 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.

  12. 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.

  13. Light induced hydrophilicity and osteoblast adhesion promotion on amorphous TiO2.

    PubMed

    Terriza, Antonia; Díaz-Cuenca, Aránzazu; Yubero, Francisco; Barranco, Angel; González-Elipe, Agustín R; Gonzalez Caballero, Juan Luis; Vilches, José; Salido, Mercedes

    2013-04-01

    We have studied the effect of the UV induced superhydrophilic wetting of TiO(2) thin films on the osteoblasts cell adhesion and cytoskeletal organization on its surface. To assess any effect of the photo-catalytic removal of adventitious carbon as a factor for the enhancement of the osteoblast development, 100 nm amorphous TiO(2) thin layers were deposited on polyethylene terephthalate (PET), a substrate well known for its poor adhesion and limited wettability and biocompatibility. The TiO(2) /PET materials were characterized by X-ray photoelectron spectroscopy, and atomic force microscopy and their wetting behavior under light illumination studied by the sessile drop method. The amorphous TiO(2) thin films showed a very poor photo-catalytic activity even if becoming superhydrophilic after illumination. The illuminated samples recovered partially its initial hydrophobic state only after their storage in the dark for more than 20 days. Osteoblasts (HOB) were seeded both on bare PET and on TiO(2) /PET samples immediately after illumination and also after four weeks storage in darkness. Cell attachment was much more efficient on the immediately illuminated TiO(2)/PET samples, with development of focal adhesions and cell traction forces. Although we cannot completely discard some photo-catalytic carbon removal as a factor contributing to this cell enhanced attachment, our photodegradation experiments on amorphous TiO(2) are conclusive to dismiss this effect as the major cause for this behavior. PMID:22965473

  14. Air detoxification with nanosize TiO2 aerosol tested on mice.

    PubMed

    Besov, A S; Krivova, N A; Vorontsov, A V; Zaeva, O B; Kozlov, D V; Vorozhtsov, A B; Parmon, V N; Sakovich, G V; Komarov, V F; Smirniotis, P G; Eisenreich, N

    2010-01-15

    A method for fast air purification using high concentration aerosol of TiO(2) nanoparticles is evaluated in a model chemical catastrophe involving toxic vapors of diisopropyl fluorophosphate (DFP). Mice are used as human model in a closed 100 dm(3) chamber. Exposure of mice to 37 ppm of DFP vapor for 15 min resulted in acute poisoning. Spraying TiO(2) aerosol in 2 min after the start of exposure to DFP vapors resulted in quick removal of DFP vapors from the chamber's air. Animals did not show signs of poisoning after the decontamination experiment and exposure to TiO(2) aerosol alone. Reactive oxygen species (ROS) and antioxidant activity (AOA) of mice blood plasma were measured for animals exposed to sound of aerosol generator, DFP vapors, TiO(2) aerosol and DFP vapors+TiO(2) aerosol. Reduced ROS and increased AOA were found for mice exposure to sound, DFP and TiO(2) aerosol. Exposure to DFP and decontamination with TiO(2) nanoparticles resulted in decreased AOA in 48 h following the exposure. The results suggest that application of TiO(2) aerosol is a powerful method of air purification from toxic hydrolysable compounds with moderate health aftermaths and requires further study and optimization. PMID:19765900

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Layered TiO2 :PVK nano-composite thin films for photovoltaic applications. TiO2 :PVK nano-composite thin films

    NASA Astrophysics Data System (ADS)

    Kaune, G.; Wang, W.; Metwalli, E.; Ruderer, M.; Roßner, R.; Roth, S. V.; Müller-Buschbaum, P.

    2008-05-01

    The influence of the solvent used for spin-coating on the homogeneity of poly(N-vinylcarbazole) (PVK) films is investigated. Homogenous films are obtained only by the use of toluene, solution in tetrahydrofuran (THF) and chloroform results in radially oriented inhomogeneities and films prepared by use of N-methylpyrrolidone and dimethylacetamide show particle formation during spin-coating. Layered nano-composite thin films are prepared by spin-coating a PVK film on top of a nano-structured titanium dioxide ( TiO2 layer. The TiO2 thin films are prepared by a sol-gel process using an amphiphilic copolymer as structure-directing agent. Structural characterisation of the TiO2 :PVK nano-composite films is done by field emission scanning electron microscopy (FESEM) and grazing-incidence small-angle scattering (GISAXS). Bare TiO2 films are probed for comparison. Light is basically only absorbed in the ultraviolet regime and absorption slightly increases upon addition of PVK, which makes the layered TiO2 :PVK nano-composite thin films good candidates for UV photovoltaic devices. Furthermore, absorption remains stable over a period of several days.

  20. Directly patterned TiO2 nanostructures for efficient light harvesting in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ram, Sanjay K.; Rizzoli, Rita; Desta, Derese; Jeppesen, Bjarke R.; Bellettato, Michele; Samatov, Ivan; Tsao, Yao-Chung; Johannsen, Sabrina R.; Neuvonen, Pekka T.; Pedersen, Thomas Garm; Pereira, Rui N.; Pedersen, Kjeld; Balling, Peter; Nylandsted Larsen, Arne

    2015-09-01

    A novel, scalable, and low-cost strategy for fabricating sub-wavelength scale hierarchical nanostructures by direct patterning of TiO2 nanoparticles on glass substrates is reported. Two nanostructural designs of light-trapping back-surface reflectors (BSR) have been fabricated for increasing the photon-harvesting properties of thin-film solar cells: a quasi-periodic nano-crater design and a random nano-bump design. The efficient light-scattering properties of the nano-crater design over a broad wavelength range are demonstrated by the measured haze factor being larger than 40% at wavelengths (~700 nm) near the band edge of amorphous silicon (a-Si:H). The a-Si:H-based n-i-p solar cell fabricated with an only ~200 nm thick absorber layer on the nano-crater BSR shows a short-circuit current density (J sc) of ~16.1 mA cm-2 representing a 28% enhancement compared to the cell deposited on a non-textured flat substrate. Measurements of the external quantum efficiency of the cell fabricated on the quasi-periodic nano-crater surface at long wavelengths, λ  >  700 nm, demonstrate an increase of a factor of 5 relative to that of a flat reference solar cell. The theoretical modeling results of optical absorption corroborate well with the experimental findings and are used to identify the volumes of strong optical absorption in the a-Si:H active layer of the textured BSR devices.

  1. Photocatalysis of Phenolic Compounds with Synthesized Nanoparticles TiO2/Sn2

    NASA Astrophysics Data System (ADS)

    Khuanmar, Kulyakorn; Wirojanagud, Wanpen; Kajitvichyanukul, Puangrat; Maensiri, Santi

    This study was aimed to determine the photocatalytic degradation of phenolic compounds contaminated in the pulp and paper wastewater with the synthesized nanoparticle TiO2/Sn2 and the commercial TiO2 (Sigma Aldrich). The studied phenolic compounds included 2-methoxy phenol (guaiacol), 2,6-dimethoxy phenol (syringol) and phenol. The synthesized TiO2/Sn2 was prepared by sol-gel technique, mixture of titanium solution and ethanol/polymer with 2% of tin. The characterization of the synthesized TiO2/Sn2 and the commercial TiO2 were performed by XRD, BET and SEM. The synthesized TiO2/Sn2 were: mixed phase of anatase:rutile of 85: 15, 14 nm crystalline size of anatase (101) and 47 nm rutile (110) and 65.7 m2 g-1 surface area by BET. On the other hand the commercial TiO2 (Sigma aldrich) only showed the anatase phase with particle size of 41 nm and 10.9 m2 g-1 surface area by BET. The photocatalytic degradation were tested on the individual and mixed phenolic compounds. The phenolic compound solution suspended with the catalyst was irradiated with UV light. The photocatalytic degradation of phenolic compounds by such two types was significantly different. TiO2/Sn2 presented the sequential degradation as syringol > guaiacol > phenol for both individual and mixed phenolic compounds. While the commercial TiO2 indicated the degradation as phenol>guaiacol>syringol for the individual phenolic compound and the reverse order of degradation as syringol>guaiacol>phenol for the mixed compounds.

  2. Structural and optoelectronic characterization of TiO2 films prepared using the sol gel technique

    NASA Astrophysics Data System (ADS)

    Jiménez González, A. E.; Gelover Santiago, S.

    2007-07-01

    TiO2 is a versatile material that makes for fascinating study in any of its several physical forms: monocrystal, polycrystal, powder or thin film. Its enhanced photosensitivity to UV radiation and excellent chemical stability in acidic and aqueous media point to its excellent potential for use in a variety of applications, such as solar cells, electronic devices, chemical sensors and photocatalysts. Of late, thin films of TiO2 have permitted the study of physical and chemical properties that are almost impossible to examine in powders. Using the sol-gel technique, it was possible to prepare TiO2 films, and to specifically modify their characteristic properties by means of annealing treatments. Optical measurements carried out on sol-gel derived films produced results similar to those found in films prepared using the sputtering technique. The use of TiO2 films facilitates the study of the behaviour of crystalline structure, grain size, photoresponse, electrical conductivity in both darkness and light and energy band gap (Eg) as a function of treatment temperature. For the first time, it has been demonstrated that the photoconductivity of TiO2 becomes apparent at a treatment temperature of 350 °C, which means that below this temperature the material is not photosensitive. The photosensitivity (S) of TiO2 films prepared by the sol-gel technique reaches values between 100 and 104, surpassing by more than two orders of magnitude the photosensitivity of TiO2 in powder form. In addition, it was possible to study the surface crystalline structure, where TEM studies clearly revealed both the polycrystalline order and the atomic arrangements of the TiO2 films. Our findings will afford us an opportunity to better study the nature of TiO2 and to enhance its performance with respect to the above-mentioned applications.

  3. 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. 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. PMID:19758597

  5. Beneficial surface passivation of hydrothermally grown TiO2 nanowires for solar water oxidation

    NASA Astrophysics Data System (ADS)

    Yun, Gun; Song, Gwang Yeom; Ahn, Bo-Eun; Lee, Sang-Kwon; Heo, Jaeyeong; Ahn, Kwang-Soon; Kang, Soon Hyung

    2016-03-01

    Rutile TiO2 nanowires (TONWs) with a length of 2.0 μm were synthesized using a facile hydrothermal method in a strong acid solution. To investigate the effect of surface passivation of TONW arrays, a TiO2 layer with a thickness varying from 5 to 20 nm on TONW arrays was applied by atomic layer deposition (ALD). No distinct morphological modification was observed in all prepared TONW arrays in the environment where the diameter of the TONW arrays was systematically increased from 10 to 40 nm. In this study, Mott-Schottky analysis revealed that 10 nm TiO2-coated TONW (denoted as TiO2(10 nm)/TONW) arrays showed the highest electronic conductivity, followed by the 5 nm, 20 nm, and 0 nm TiO2/TONW arrays. The photoelectrochemical (PEC) performance was assessed in 0.1 M KOH, which revealed that TiO2(10 nm)/TONW arrays displayed a photocurrent density (3.92 mA/cm2 at 0.5 VNHE) higher than that (2.72 mA/cm2) of TONW arrays. This may be ascribed to the surface passivation of trap or defect sites by the thin TiO2 surface coating, leading to the increased electron densities and improving the PEC performance. For a more definitive examination, photovoltage decay measurement was performed to calculate the decay lifetime, which is closely correlated to the electron-hole recombination reaction. In this study, TiO2(10 nm)/TONW arrays exhibited a decay lifetime (0.7 s) shorter than that (1.1 s) of TONW arrays, proving the suppressed charge recombination in the thin TiO2/TONW arrays.

  6. 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.

  7. Electrochromism in sol-gel deposited TiO2 films

    NASA Astrophysics Data System (ADS)

    Bell, John M.; Barczynska, Joanna; Evans, L. A.; MacDonald, Kathleen A.; Wang, J.; Green, David C.; Smith, Geoffrey B.

    1994-09-01

    Electrochromism is sol-gel deposited TiO2 films and films containing TiO2 and WO3 has been observed. The films are deposited by dip-coating from a precursor containing titanium isopropoxide in ethanol or titanium propoxide in ethanol, and after deposition the films are heat treated to between 250 degree(s)C and 300 degree(s)C. The films do not show any signs of crystallinity. However substantial coloration is observed using Li+ ions in a non-aqueous electrolyte, both in pure TiO2 films and in mixed metal oxide films (WO3:TiO2), although the voltage required to produce coloration is different in the two cases. Results will be presented detailing the optical switching and charge transport properties of the films during cyclic voltammetry. These results will be used to compare the performance of the TiO2 films with other electrochromics. The TiO2 and mixed metal films all color cathodically, and the colored state is a neutral greyish color for TiO2, while the bleached state is transparent and colorless, Results on coloration efficiency and the stability under repeated electrochemical cycling will also be presented. The neutral color of the TiO2 films and mixed-metal films means that electrochromic windows based on TiO2 may have significant advantages over WO3-based windows. A detailed analysis of the optical properties of the colored state of the films will be presented. The dynamics of coloration for these films is also under investigation, and preliminary results will be presented.

  8. 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

  9. 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.

  10. 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.

  11. Electrolyte/photoanode engineered performance of TiO2 based dye sensitised solar cells

    NASA Astrophysics Data System (ADS)

    Divya, S.; Thankappan, Aparna; Vallabhan, C. P. G.; Nampoori, V. P. N.; Radhakrishnan, P.; Mujeeb, A.

    2014-02-01

    The performance of dye sensitized solar cells (DSSCs) depends on the collective contribution from its constituents which include the nanoparticle film, dye, electrolyte, and the counter electrode. In this report, we have tried to elucidate the varying performance of the TiO2 based DSSCs standardised using N719 dye and Platinum as counter electrode with various electrolytes including quasi static electrolytes. We have also evaluated the photovoltaic characteristics of the cells employing different morphological structured TiO2 photoanode. The DSSC based on the hierarchical anatase TiO2 nanotree photoelectrode showed the highest light-to-electricity conversion efficiency of 10.2%.

  12. Behavior of TiO2 thin film in a nanocapacitor.

    PubMed

    Jia, Dongdong; Shaffer, C; Pickering, S; Goonewardene, A; Wang, Xiao-Jun

    2008-03-01

    Gold and platinum nanocapacitors have been fabricated using a magnetron sputtering technique. TiO2 is used as a dielectric material to separate the metal layers which act as the parallel plates for the capacitors. The thickness for metal films and TiO2 layer is 80 nm and 400 nm, respectively. Capacitance of the nanocapacitors has been measured and dielectric constant of TiO2 calculated. Both capacitance and dielectric constant are observed to have strong frequency dependence. PMID:18468130

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

    DOE PAGESBeta

    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

  14. Effect of Mg ion bioactivity on the TiO2 nano-network surface.

    PubMed

    Jung, Sang-Chul; Lee, Kang; Seo, Ki-Won; Lee, Woo-Geun; Kim, Byung-Hoon

    2013-01-01

    Magnesium (Mg) ion is well known for improving the Ca-P nucleation and growth. TiO2 nano-network (NT) surface was prepared by alkali-treatment. To introduce the Mg ion to TiO2 NT surface, acrylic acid plasma polymerization was used. Bioactivity of the Mg ions coated samples was evaluated by immersed in simulated body fluid (SBF). Surface morphology and chemical composition of all samples were characterized by SEM, XRD and XPS. Mg ion promotes hydroxyapatite (HA) nucleation and growth on TiO2 NT in SBF and improves crystallinity of HA deposited layer. PMID:23646785

  15. 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

  16. Improved photocatalytic activity of zeolite- and silica-incorporated TiO2 film.

    PubMed

    Tanaka, K; Fukuyoshi, J; Segawa, H; Yoshida, K

    2006-09-21

    Porous TiO2 film was prepared by sol-gel method from TiO2 sol containing polyvinylpyrolidone (PVP). Photocatalytic activity of the film was evaluated by the elimination rate of ethylene. Several adsorbents including zeolite and silica powders were incorporated into the TiO2 film. All the adsorbents enhanced the activity. The optimum adsorbent content was 0.005-0.01 g/ml of the coating sol solution. Silica provided better activity than zeolite. At high humidity and in dry air the activity decreased. PMID:16704899

  17. TiO2 controlling photoluminescence of AWO4 (A =Ca,Sr,Ba) nanofilms

    NASA Astrophysics Data System (ADS)

    Jia, Runping; Zhang, Guoxin; Wu, Qingsheng; Ding, Yaping

    2006-07-01

    AWO4 (A =Ca,Sr,Ba) nanofilms are prepared by a self-inventive technique using collodion to disperse nanoparticles and form film, and their photoluminescence (PL) properties are controlled by a nano-TiO2 doping method. This cannot only reach the results of uniform film and PL enhancement, but also realize a PL increase/decrease shift effect. The PL behaviors of AWO4 nanofilms doped by TiO2 are in good agreement with Gaussion function relation. In addition, there is a positive correlation between the critical concentrations of TiO2 in AWO4-TiO2 nanofilm series and A's ionic potential.

  18. N-Ion-implanted TiO2 photoanodes in quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sudhagar, P.; Asokan, K.; Ito, E.; Kang, Yong Soo

    2012-03-01

    Hierarchical nanostructured titanium dioxide (TiO2) clumps were fabricated using electrostatic spray with subsequent nitrogen-ion doping by an ion-implantation technique for improvement of energy conversion efficiency for quantum dot-sensitized solar cells (QDSCs). CdSe quantum dots were directly assembled on the produced N-ion-implanted TiO2 photoanodes by chemical bath deposition, and their photovoltaic performance was evaluated in a polysulfide electrolyte with a Pt counter electrode. We found that the photovoltaic performance of TiO2 electrodes was improved by nearly 145% upon N-ion implantation. The efficiency improvement seems to be due to (1) the enhancement of electron transport through the TiO2 layer by inter-particle necking of primary TiO2 particles and (2) an increase in the recombination resistance at TiO2/QD/electrolyte interfaces by healing the surface states or managing the oxygen vacancies upon N-ion doping. Therefore, N-ion-doped photoanodes offer a viable pathway to develop more efficient QD or dye-sensitized solar cells.Hierarchical nanostructured titanium dioxide (TiO2) clumps were fabricated using electrostatic spray with subsequent nitrogen-ion doping by an ion-implantation technique for improvement of energy conversion efficiency for quantum dot-sensitized solar cells (QDSCs). CdSe quantum dots were directly assembled on the produced N-ion-implanted TiO2 photoanodes by chemical bath deposition, and their photovoltaic performance was evaluated in a polysulfide electrolyte with a Pt counter electrode. We found that the photovoltaic performance of TiO2 electrodes was improved by nearly 145% upon N-ion implantation. The efficiency improvement seems to be due to (1) the enhancement of electron transport through the TiO2 layer by inter-particle necking of primary TiO2 particles and (2) an increase in the recombination resistance at TiO2/QD/electrolyte interfaces by healing the surface states or managing the oxygen vacancies upon N-ion doping. Therefore, N-ion-doped photoanodes offer a viable pathway to develop more efficient QD or dye-sensitized solar cells. Electronic supplementary information (ESI) available: Details of SRIM 2008 simulation, optical absorption, and Bode plots. See DOI: 10.1039/c2nr11953f

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

    NASA Astrophysics Data System (ADS)

    Choudhuri, Bijit; Mondal, Aniruddha; Saha, Ardhendu

    2016-05-01

    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.

  20. 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.

  1. Impact of bimetal electrodes on dielectric properties of TiO2 and Al-doped TiO2 films.

    PubMed

    Kim, Seong Keun; Han, Sora; Jeon, Woojin; Yoon, Jung Ho; Han, Jeong Hwan; Lee, Woongkyu; Hwang, Cheol Seong

    2012-09-26

    Rutile structured Al-doped TiO(2) (ATO) and TiO(2) films were grown on bimetal electrodes (thin Ru/thick TiN, Pt, and Ir) for high-performance capacitors. The work function of the top Ru layer decreased on TiN and increased on Pt and Ir when it was thinner than ~2 nm, suggesting that the lower metal within the electrodes influences the work function of the very thin Ru layer. The use of the lower electrode with a high work function for bottom electrode eventually improves the leakage current properties of the capacitor at a very thin Ru top layer (≤2 nm) because of the increased Schottky barrier height at the interface between the dielectric and the bottom electrode. The thin Ru layer was necessary to achieve the rutile structured ATO and TiO(2) dielectric films. PMID:22869517

  2. Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres: Splitting of magnetic dipole modes in anisotropic TiO 2 micro-spheres

    DOE PAGESBeta

    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

  3. 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. PMID:16269195

  4. Biological response to nano-scale titanium dioxide (TiO2): role of particle dose, shape, and retention.

    PubMed

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

    2013-01-01

    Titanium dioxide (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 (1) establish a lowest-observed-effect level (LOEL) for nano-scale TiO2, (2) determine TiO2 uptake in the lungs, and (3) estimate toxicity based on physicochemical 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 administered TiO2 (0, 20, 70, or 200 μg) via intratracheal instillation. Bronchoalveolar lavage fluid (BALF) and lung tissue were obtained for analysis 1 and 7 d post exposure. Despite abundant TiO2 inclusions in all exposed animals, only TiO2-NB displayed any significant degree of inflammation seen in BALF at the 1-d time point. This inflammation resolved by 7 d, although TiO2 particles had not cleared from alveolar macrophages recovered from the lung. Histological examination showed TiO2-NB produced cellular changes at d 1 that were still evident at d 7. Data indicate TiO2-NB is the most inflammatory with a LOEL of 200 μg at 1 d post instillation. PMID:24156719

  5. Enhancing photoactivity of TiO2(B)/anatase core-shell nanofibers by selectively doping cerium ions into the TiO2(B) core.

    PubMed

    Yang, Dongjiang; Zhao, Jian; Liu, Hongwei; Zheng, Zhanfeng; Adebajo, Moses O; Wang, Hongxia; Liu, Xiaotang; Zhang, Hongjie; Zhao, Jin-cai; Bell, John; Zhu, Huaiyong

    2013-04-15

    Cerium ions (Ce(3+)) can be selectively doped into the TiO2(B) core of TiO2(B)/anatase core-shell nanofibers by means of a simple one-pot hydrothermal treatment of a starting material of hydrogen trititanate (H2Ti3O7) nanofibers. These Ce(3+) ions (≈0.202 nm) are located on the (110) lattice planes of the TiO2(B) core in tunnels (width≈0.297 nm). The introduction of Ce(3+) ions reduces the defects of the TiO2(B) core by inhibiting the faster growth of (110) lattice planes. More importantly, the redox potential of the Ce(3+)/Ce(4+) couple (E°(Ce(3+)/Ce(4+))=1.715 V versus the normal hydrogen electrode) is more negative than the valence band of TiO2(B). Therefore, once the Ce(3+)-doped nanofibers are irradiated by UV light, the doped Ce(3+) ions--in close vicinity to the interface between the TiO2(B) core and anatase nanoshell--can efficiently trap the photogenerated holes. This facilitates the migration of holes from the anatase shell and leaves more photogenerated electrons in the anatase nanoshell, which results in a highly efficient separation of photogenerated charges in the anatase nanoshell. Hence, this enhanced charge-separation mechanism accelerates dye degradation and alcohol oxidation processes. The one-pot treatment doping strategy is also used to selectively dope other metal ions with variable oxidation states such as Co(2+/3+) and Cu(+/2+) ions. The doping substantially improves the photocatalytic activity of the mixed-phase nanofibers. In contrast, the doping of ions with an invariable oxidation state, such as Zn(2+), Ca(2+), or Mg(2+), does not enhance the photoactivity of the mixed-phase nanofibers as the ions could not trap the photogenerated holes. PMID:23417892

  6. 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.

  7. 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

  8. 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

  9. Understanding electronic and optical properties of anatase TiO2 photocatalysts co-doped with nitrogen and transition metals.

    PubMed

    Meng, Qingsen; Wang, Tuo; Liu, Enzuo; Ma, Xinbin; Ge, Qingfeng; Gong, Jinlong

    2013-06-28

    This paper describes an investigation into the general trend in electronic properties of anatase TiO2 photocatalysts co-doped with transition metals and nitrogen employing first-principles density functional theory. Fourteen different transition metals (M), including Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, and Cd, have been considered. The characteristic band structures of the co-doping systems involving the transition metal series are presented. Our results indicate that the absorption edges of TiO2 are shifted to the visible-light region upon introduction of dopants, due to the reduced conduction band minimum (CBM) and the formation of impurity energy levels (IELs) in the band gap. These IELs are primarily formed from (a) the anti-bonding orbitals of the M-O (M indicates the doped transition metal) bonds, (b) the unsaturated nonbonding d orbitals of the doped transition metal (mainly d(xy), d(yz), and d(xz)), and (c) the Ti-O bonding/Ti-N anti-bonding orbitals of the bond next to the doped transition metal. When the valence d electrons of the doped metal are between 3 and 7, all three types of IELs appear in the band gap of the (M, N) co-doped systems. For systems doped with a metal of more than 7 valence electrons, only types (a) and (c) of IELs as well as the unoccupied pz state of N are observed. Based on our analysis, we propose that the co-doping systems such as (V, N), (Cr, N), and (Mn, N), which have the IELs with a significant bandwidth, are of great potential as candidates for photovoltaic applications in the visible light range. PMID:23652827

  10. Electron transfer in colloidal TiO 2 semiconductors sensitized by hypocrellin A

    NASA Astrophysics Data System (ADS)

    Zhou, Zhixiang; Qian, Suping; Yao, Side; Zhang, Zhiyi

    2002-10-01

    The electron transfer from singlet states of hypocrellin A (HA) to colloidal TiO 2 nanometer-sized particles has been examined by absorption, fluorescence quenching, fluorescence lifetime measurements, laser flash photolysis and pulse radiolysis techniques. Adsorption of HA onto the surface of TiO 2 particles extended its absorption spectrum further into the visible region, and the apparent association constant ( Kapp) for the association between HA and colloidal TiO 2 was 3600 (mol/l) -1 determined by fluorescence quenching method. Fluorescence lifetime measurement was used to elucidate the process of electron transfer from the singlet state of HA to conduction band of TiO 2 ( Ket=4.26×10 9 s -1). Laser flash photolysis and pulse radiolysis studies demonstrated formation of the radical cation of HA.

  11. PCDDs, PCDFs, and PCBs co-occurrence in TiO2 nanoparticles.

    PubMed

    Ctistis, Georgios; Schön, Peter; Bakker, Wouter; Luthe, Gregor

    2016-03-01

    In the present study, we report on the co-occurrence of persistent organic pollutants (POPs) adsorbed on nanoparticular titanium dioxide (TiO2). We report on the finding of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) on the surface of commercially available TiO2 nanoparticles, being formed during the fabrication process of the TiO2. Thereby, the samples comprise PCBs with higher congener numbers or, in the absence of PCBs, a high concentration of PCDDs and PCDFs. This new class of POPs on an active catalytic surface and the great range of applications of nanoparticular TiO2, such as in color pigments, cosmetics, and inks, give rise to great concern due to their potential toxicity. PMID:26545886

  12. 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

  13. Photocatalytic activity of nanosized TiO2 thin film prepared by magnetron sputtering method.

    PubMed

    Kang, Sang-Jun; Kim, Ki-Joong; Chung, Min-Chul; Jung, Sang-Chul; Boo, Su-Il; Cho, Soon Kye; Jeong, Woon-Jo; Ahn, Ho-Geun

    2011-02-01

    Nanosized TiO2 thin film on the substrate such as stainless steel plate and slide glass film were prepared by magnetron sputtering method, and these TiO2 thin films were characterized by field emission-scanning electron microscopy (FE-SEM). Photocatalytic activity for Methyl-ethyl-ketone (MEK) and acetaldehyde were measured using a closed circulating reaction system through the various ultra violet (UV) sources. From the results of SEM images, nanosized TiO2 thin film was uniformly coated on slide glass, ranging from 360 nm to 370 nm. Photocatalytic activity of MEK over TiO2 thin film on stainless steel plate did not occur by UV-A irradiation, but was efficiently decomposed by UV-B and UV-C. Also, acetaldehyde could be decomposed than MEK. The effect of sputtering conditions on their structure and photocatalytic activities were investigated in detail. PMID:21456269

  14. Enhanced optical properties of TiO2 nanoceramic films by oxygen atmosphere.

    PubMed

    Lin, Su-Shia; Wu, Ding-Kun

    2010-02-01

    TiO2 nanoceramic films were deposited on glasses by rf magnetron sputtering and corresponded to nanocrystalline anatase. The porosity and surface roughness decreased with the oxygen pressure. The optical transmission of TiO2 nanoceramic films obviously increased with the decrease of film thickness or the increase of oxygen pressure, especially in the visible region. Moiré deflectometry was used to measure the nonlinear refractive indices of TiO2 films deposited in a mixed Ar-O2 atmosphere. The nonlinear refractive index was measured to be of the order of 10(-8) cm2 W(-1) and the change in refractive index was of the order of 10(-5). As the oxygen pressure increased, the transparent TiO2 film exhibited a high linear refractive index, a low stress and a low stress-optical coefficient. PMID:20352762

  15. 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.

  16. Transport properties in single-crystalline rutile TiO2 nanorods

    NASA Astrophysics Data System (ADS)

    Chen, R. S.; Chen, C. A.; Wang, W. C.; Tsai, H. Y.; Huang, Y. S.

    2011-11-01

    Electronic transport properties of the single-crystalline titanium dioxide (TiO2) nanorods (NRs) with single rutile phase have been investigated. The conductivity values for the individual TiO2 NRs grown by metal-organic chemical vapor deposition are in the range of 1-10 Ω-1 cm-1. The temperature-dependent measurement shows the presence of two shallow donor levels/bands with activation energies at 8 and 28 meV, respectively. On the photoconductivity (PC), the TiO2 NRs exhibit the much higher normalized PC gain and sensitive excitation-power dependence than the polycrystalline nanotubes. The results demonstrate the superior photoconduction efficiency and distinct mechanism in the monocrystalline one-dimensional TiO2 nanostructures in comparison to the polycrystalline or nanoporous counterparts.

  17. TiO2 hollow microspheres with mesoporous surface: Superior adsorption performance for dye removal

    NASA Astrophysics Data System (ADS)

    Wang, Ran; Cai, Xia; Shen, Fenglei

    2014-06-01

    TiO2 hollow microspheres with mesoporous surface were synthesized by a facile template-assisted solvothermal reaction. The adsorption performance of TiO2 hollow microspheres for removing Methylene Blue from aqueous solution has been investigated. The comparative adsorption study indicated that adsorption capacity of TiO2 hollow microspheres with mesoporous surface is markedly higher than that of solid microsphere. The equilibrium data fitted well with the Langmuir model and the maximum adsorption capacity reached 196.83 mg/g. The kinetics of dye adsorption followed the pseudo-second-order model and the adsorbed dye could be degraded completely by the subsequent photocatalytic process. These TiO2 hollow microspheres can be considered as a low-cost alternative adsorbent for removal of organic pollutants from wastewater.

  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. 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

  20. 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.

  1. Photocatalytic activity of heterostructures based on TiO2 and halloysite nanotubes.

    PubMed

    Wang, Rijing; Jiang, Guohua; Ding, Yuanwei; Wang, Yin; Sun, Xinke; Wang, Xiaohong; Chen, Wenxing

    2011-10-01

    A one-step solvothermal method was used to prepare TiO(2)/halloysite composites. TiO(2) nanoparticles were deposited on the platform of the halloysite nanotubes (HNTs). XRD, FT-IR, FE-SEM, and TEM were applied to investigate the structures and morphologies of the resultant samples. The as-prepared TiO(2)/HNTs photocatalyst exhibits pH sensibility on the degradation of methanol and a higher photocatalytic activity on the degradation of acetic acid. The combination of the photocatalytic property of TiO(2) and the unique structure of halloysite endowed this material with a bright perspective in degradation of organic pollutant. PMID:21916434

  2. 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.

  3. TIO2 ADVANCED PHOTO-OXIDATION TECHNOLOGY: EFFECT OF ELECTRON ACCEPTORS

    EPA Science Inventory

    The effects of electron acceptors (additives) such as hydrogen peroxide, ammonium persulphate, potassium bromate and potassium peroxymonosulphate (ozone) on the TiO2 photocatalytic degradation of various organic pollutants were examined at various conditions. he individual and th...

  4. A stable, label-free optical interferometric biosensor based on TiO2 nanotube arrays.

    PubMed

    Mun, Kyu-Shik; Alvarez, Sara D; Choi, Won-Youl; Sailor, Michael J

    2010-04-27

    Optical interferometry of a thin film array of titanium dioxide (TiO2) nanotubes allows the label-free sensing of rabbit immunoglobulin G (IgG). A protein A capture probe is used, which is immobilized on the inner pore walls of the nanotubes by electrostatic adsorption. Control experiments using IgG from chicken (which does not bind to protein A) confirms the specificity of the protein A-modified TiO2 nanotube array sensor. The aqueous stability of the TiO2 nanotube array was examined and compared with porous silica (SiO2), a more extensively studied thin film optical biosensor. The TiO2 nanotube array is stable in the pH range 2 to 12, whereas the porous SiO2 sensor displays significant degradation at pH > 8. PMID:20356100

  5. Ultralong Rutile TiO2 Nanowire Arrays for Highly Efficient Dye-Sensitized Solar Cells.

    PubMed

    Li, Hailiang; Yu, Qingjiang; Huang, Yuewu; Yu, Cuiling; Li, Renzhi; Wang, Jinzhong; Guo, Fengyun; Jiao, Shujie; Gao, Shiyong; Zhang, Yong; Zhang, Xitian; Wang, Peng; Zhao, Liancheng

    2016-06-01

    Vertically aligned rutile TiO2 nanowire arrays (NWAs) with lengths of ∼44 μm have been successfully synthesized on transparent, conductive fluorine-doped tin oxide (FTO) glass by a facile one-step solvothermal method. The length and wire-to-wire distance of NWAs can be controlled by adjusting the ethanol content in the reaction solution. By employing optimized rutile TiO2 NWAs for dye-sensitized solar cells (DSCs), a remarkable power conversion efficiency (PCE) of 8.9% is achieved. Moreover, in combination with a light-scattering layer, the performance of a rutile TiO2 NWAs based DSC can be further enhanced, reaching an impressive PCE of 9.6%, which is the highest efficiency for rutile TiO2 NWA based DSCs so far. PMID:27097727

  6. 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.

  7. Mesoporous Foam TiO2 Nanomaterials for Effective Hydrogen Production.

    PubMed

    Krishnappa, Manjunath; Souza, Virgínia S; Ganganagappa, Nagaraju; Scholten, Jackson D; Teixeira, Sérgio R; Dupont, Jairton; Thippeswamy, Ramakrishnappa

    2015-12-01

    Hydrolysis of TiCl4 in a diether-functionalized imidazolium ionic liquid (IL), namely 1-methyl-3-[2-(2-methoxy(ethoxy)ethyl]imidazolium methane sulfonate (M(MEE)I⋅CH3 SO3 ), results in a heterostructured organic/inorganic and sponge-like porous TiO2 material. The thermal treatment (300 °C) followed by calcination (500 °C) affords highly porous TiO2 . The characterization of the obtained samples (with and without IL, before and after calcination) by XRD, SEM, and TEM reveals TiO2 anatase crystalline phases and irregular-shaped particles with different porous structures. These hierarchical-structured mesoporous TiO2 nanomaterials were employed as efficient photocatalysts in the water-splitting process, yielding up to 1304 μmol g(-1) on hydrogen production. PMID:26492871

  8. 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.

  9. 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

  10. 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

  11. 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...

  12. 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.

  13. Self-assembled TiO2-Graphene Hybrid Nanostructures for Enhanced Li-ion Insertion

    SciTech Connect

    Wang, Donghai; Choi, Daiwon; Li, Juan; Yang, Zhenguo; Nie, Zimin; Kou, Rong; Hu, Dehong; Wang, Chong M.; Saraf, Laxmikant V.; Zhang, Jiguang; Aksay, Ilhan A.; Liu, Jun

    2009-04-01

    We used anionic sulfate surfactants to assist the stabilization of graphene in aqueous solutions and facilitate the self-assembly of in-situ grown nanocrystalline TiO2, rutile and anatase, with graphene. These nanostructured TiO2-graphene hybrid materials were used for investigation of Li-ion insertion properties. The hybrid materials showed significantly enhanced Li-ion insertion/extraction in TiO2. The specific capacity was more than doubled at high charge rates, as compared with the pure TiO2 phase. The improved capacity at high charge-discharge rate may be attributed to increased electrode conductivity in presence of a percolated graphene network embedded into the metal oxide electrodes.

  14. Preparation and photoluminescence properties of europium ions doped TiO2 nanocrystals.

    PubMed

    Liu, Hai; Yu, Lixin

    2013-07-01

    In this paper, pure and Eu3+ doped TiO2 nanocrystals (NCs) have been fabricated successfully by a two steps of sol-gel and hydrothermal methods. The microstructures, morphologies and photoluminescent properties of Eu(3+)-TiO2 were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence spectroscopy (PL). XRD and PL results show that the existent of rare earth can inhibit the transformation of TiO2 NCs from anatase to rutile phase and can improve the luminescence intensity of the prepared samples. The room-temperature PL emission of the as-grown samples is dominated by the 5D(0)-7F(j) transitions of Eu3+ ions. But the luminescence intensity drops dramatically when the annealing temperature reaches a relatively high degree because of the formation of the rutile phase of TiO2 NCs hosts. PMID:23901539

  15. 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.

  16. 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.

  17. 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).

  18. 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.

  19. Phase stability frustration on ultra-nanosized anatase TiO2.

    PubMed

    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

  20. High performance binderless TiO2 nanowire arrays electrode for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Li, Yueming; Lv, Xiaojun; Li, Jinghong

    2009-09-01

    Binderless lithium ion battery electrode fabricated by anodizing Ti foil, in which TiO2 nanowire serves as active materials and unreacted Ti foil as the current collector, exhibited high electrochemical performance.

  1. UV/thermally driven rewritable wettability patterns on TiO2-PDMS composite films.

    PubMed

    Nakata, Kazuya; Kimura, Hiroaki; Sakai, Munetoshi; Ochiai, Tsuyoshi; Sakai, Hideki; Murakami, Taketoshi; Abe, Masahiko; Fujishima, Akira

    2010-09-01

    Composite films of TiO2 and polydimethylsiloxane (PDMS) are prepared by a sol-gel method, cured with UV irradiation, and then treated in hot water to crystallize the TiO2 in the film. The presence of anatase TiO2 contributes to the photoinduced superhydrophilicity of the film under UV irradiation. Contact angle studies reveal that the TiO2-PDMS composite film recovers its original hydrophobic state. Hydrophobic-superhydrophilic patterns are successfully formed on the films. The wettability patterns can be erased by UV irradiation and thermal treatment. New wettability patterns can be reconstructed, demonstrating that the film exhibits rewritable wettability without the need for organic chemicals. PMID:20712336

  2. 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.

  3. 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

  4. 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. PMID:26891152

  5. Photocatalytic degradation of N-nitrosodimethylamine: mechanism, product distribution, and TiO2 surface modification.

    PubMed

    Lee, Jaesang; Choi, Wonyong; Yoon, Jeyong

    2005-09-01

    The photocatalytic degradation (PCD) reaction of N-nitrosodimethylamine (NDMA) in water was investigated using pure and surface-modified TiO2. The PCD products of NDMA were methylamine (MA), dimethylamine (DMA), nitrite, nitrate, and ammonium, and their distribution could be changed by modifying the surface of TiO2. The PCD reaction of NDMA seems to be initiated mostly by OH radicals, not valence band holes, because the addition of excess oxalates (hole scavengers) only moderately retarded the PCD rate. The presence of oxalate, however, enabled a new reductive transformation path in which the CO2-* radicals generated from the oxalate converted NDMA into DMA. In acidic suspensions of pure TiO2, the formation of MA was highly favored over DMA and NH3, whereas all degradation products (MA, DMA, and NH3) were generated at comparable concentrations at basic pH. It is suggested that there are three parallel paths depending on the position of the initial attack of OH radical on NDMA and the product distribution is closely related with which path is favored under a specific condition. DMA production is related to the OH radical attack on the nitrosyl nitrogen. Platinum deposition, silica loading, Nafion coating, and surface fluorination were tested to investigate the effects of TiO2 surface modification on the product distribution. The surface platinization of TiO2 had little effect on the PCD reaction of NDMA under air-equilibrated conditions but accelerated the PCD reaction under deaerated conditions. An enhanced PCD reaction of NDMA was achieved with the silica-loaded TiO2 and Nafion-coated TiO2, both of which favored the formation of DMA over MA. The PCD of NDMA on surface-fluorinated TiO2 was also highly enhanced but favored the formation of MA over the formation of DMA. PMID:16190242

  6. Zr-doped rutile TiO2: a nuclear quadrupole interaction study

    NASA Astrophysics Data System (ADS)

    Banerjee, D.; Das, S. K.; Das, P.; Thakare, S. V.; Butz, T.

    2010-04-01

    Role of Zr atom on the quadrupole interaction of 181Ta in rutile TiO2 has been investigated by time differential perturbed angular correlation (TDPAC) study. The quadrupole frequency remains same as that in the pure rutile TiO2 but its distribution increases with the amount of Zr. This indicates a metal-metal interaction between probe atom and Zr-atom in the nearest neighbour.

  7. 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.

  8. Verification of effect of electric field on electron transport in TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Chuang, Kai-Ling; Chen, Yi-Jia; Wong, Ming-Show; Ling, Hong Syuan; Tsai, Chih-Hung; Wang, Chien Chin

    2015-09-01

    We demonstrated that the dense TiO2 planar negative electrode is an effective electron transport material in the perovskite solar cells. The highest Voc is 900 mV using negative electrode with a dense TiO2 layer of 400 nm plus a mesoporous TiO2 layer of 400 nm. For conventional dye-sensitized solar cells (DSSCs) the thickness of the mesoporous negative electrode is around 15 μm. The ideal range of film thickness in DSSCs is usually 12~16 μm, suggesting that the electron has comparable diffusion length in the mesoporous negative electrode such that the electron recombination is insignificant below 15 μm. However, design of thicker mesoporous TiO2 negative electrode in perovskite solar cells is not usually encouraged as the solar cell efficiency decreases with electrode thickness greater than 500 nm. In this study, we would like to verify if the efficiency decrease of perovskite solar cells with electrode thickness is really due to the increase of thickness of TiO2 electrode itself or some consequences that come with the increase of thickness, such as increased roughness. We will report the solar cell efficiency dependence on the thickness of dense TiO2 layer in negative electrode so to verify if the electric field does play a role in electron transport in the TiO2 electrode. With this understanding, we will be able to design a novel structure of TiO2 electrode that is suitable for perovskite solar cells.

  9. Photocatalytic CO2 conversion over alkali modified TiO2 without loading noble metal cocatalyst.

    PubMed

    Meng, Xianguang; Ouyang, Shuxin; Kako, Tetsuya; Li, Peng; Yu, Qing; Wang, Tao; Ye, Jinhua

    2014-10-01

    Surface modification of TiO2 with NaOH promoted the chemisorption, activation and photocatalytic CO2 reduction. An optimized loading amount of NaOH kept a good balance between CO2 chemisorption quantity and BET surface area of TiO2. This noble metal free method provides a simple pathway for effective multiple H(+)/e(-) CO2 photoreduction. PMID:25130434

  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. PMID:25497036

  11. Magnetic and electrical properties of TiO2:Nb thin films

    NASA Astrophysics Data System (ADS)

    Yu, Chang-Feng; Sun, Shih-Jye; Chen, Jian-Ming

    2014-02-01

    This study investigated the electrical and especially the magnetic properties of Niobium (Nb) doped TiO2 (TiO2:Nb) thin films. Experiments evidently present that both minimum of ferromagnetism and resistivity exist in a same Nb doping ratio (3.0%). The XPS experiments revealed that Nb doping simultaneously increases and compensates for oxygen vacancies. The proposed model explains magnetic and electrical properties by analyzing oxygen vacancies induced by vacuum annealing or by Nb doping.

  12. Nb doped TiO2 nanotubes for enhanced photoelectrochemical water-splitting.

    PubMed

    Das, Chittaranjan; Roy, Poulomi; Yang, Min; Jha, Himendra; Schmuki, Patrik

    2011-08-01

    Nanostructured titanium dioxide is one of the classic materials for photoelectrochemical water splitting. In the present work we dope TiO(2) nanotube anodes. For this, various low concentration bulk-Nb-doped TiO(2) nanotube layers were grown by self-organizing anodization of Ti-Nb alloys. At Nb-contents around 0.1 at%, and after an adequate heat-treatment, a strongly increased and stable photoelectrochemical water-splitting rate is obtained. PMID:21761039

  13. Microglial cells (BV-2) internalize titanium dioxide (TiO2) nanoparticles: toxicity and cellular responses.

    PubMed

    Rihane, Naima; Nury, Thomas; M'rad, Imen; El Mir, Lassaad; Sakly, Mohsen; Amara, Salem; Lizard, Gérard

    2016-05-01

    Because of their whitening and photocatalytic effects, titanium dioxide nanoparticles (TiO2-NPs) are widely used in daily life. These NPs can be found in paints, plastics, papers, sunscreens, foods, medicines (pills), toothpastes, and cosmetics. However, the biological effect of TiO2-NPs on the human body, especially on the central nervous system, is still unclear. Many studies have demonstrated that the brain is one of the target organs in acute or chronic TiO2-NPs toxicity. The present study aimed to investigate the effect of TiO2-NPs at different concentrations (0.1 to 200 μg/mL) on murine microglial cells (BV-2) to assess their activity on cell growth and viability, as well as their neurotoxicity. Different parameters were measured: cell viability, cell proliferation and DNA content (SubG1 peak), mitochondrial depolarization, overproduction of reactive oxygen species (especially superoxide anions), and ultrastructural changes. Results showed that TiO2-NPs induced some cytotoxic effects with a slight inhibition of cell growth. Thus, at high concentrations, TiO2-NPs were not only able to inhibit cell adhesion but also enhanced cytoplasmic membrane permeability to propidium iodide associated with a loss of mitochondrial transmembrane potential and an overproduction of superoxide anions. No induction of apoptosis based on the presence of a SubG1 peak was detected. The microscopic observations also indicated that small groups of nanosized particles and micron-sized aggregates were engulfed by the BV-2 cells and sequestered as intracytoplasmic aggregates after 24-h exposure to TiO2-NPs. Altogether, our data show that the accumulation TiO2-NPs in microglial BV-2 cells favors mitochondrial dysfunctions and oxidative stress. PMID:26846246

  14. 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

  15. Photoconductivity and trap-related decay in porous TiO2/ZnO nanocomposites

    NASA Astrophysics Data System (ADS)

    Wu, Jun; Li, Huayao; Liu, Yuan; Xie, Changsheng

    2011-12-01

    Photoconductivity and trap-related decay were investigated in porous TiO2/ZnO nanocomposites. Photoconductivity responses of TiO2 and ZnO were completely different, which were attributed to electron-scavenging effect and hole trapping effect, respectively. When the mole ratio of TiO2:ZnO was from 9:1 to 6:4, the photoconductivity responses were consistent with TiO2. On the contrary, when the mole ratio of TiO2:ZnO was from 4:6 to 1:9, the photoconductivity responses were controlled by ZnO. Time constants were obtained by fitting the experiment data with an exponential function. We found that they tended to get larger with the percentage of ZnO while a turning point appeared at TiO2:ZnO = 1:9. The pattern was assigned to different carrier trapping mechanisms as well as carrier separation. Composition effect was defined by a quantitative formula to evaluate the recombination processes of composite materials. A mechanism was proposed to explain this phenomenon.

  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. 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

  18. 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.

  19. Degradation of parathion and the reduction of acute toxicity in TiO2 photocatalysis.

    PubMed

    Zoh, K D; Kim, T S; Kim, J G; Choi, K H

    2005-01-01

    Photocatalytic degradation of methyl parathion was done using a circulating TiO2/UV and TiO2/solar reactor. Indoor experimental results showed that, under the photocatalysis conditions, parathion was more effectively degraded than under the photolysis and TiO2 only conditions. Parathion (38 microM) was completely degraded under photocatalysis within 90 min, and more than 80% TOC decrease after 150 minutes. The main ionic byproducts during the photocatalysis were measured, and almost complete nitrogen recovery was achieved as mainly NO3- NO2-, and NH4+, and 80% of sulfur as recovered as SO4(2)-. Organic intermediates such as nitrophenol and methyl paraoxon were also identified during the photocatalysis of parathion, and these were further degraded after 90 minutes. Microtox bioassay using Vibrio fischeri was used in evaluating the toxicity of solutions treated by photocatalysis and photolysis of parathion. The results showed that the acute toxicity expressed as EC50 almost reduced after 90 min under the photocatalysis condition whereas only 40% reduction of toxicity as EC50 was achieved in photolysis condition. The outdoor results using a TiO2/solar system were similar to the TiO2 indoor system, indicating the possibility of applying TiO2/solar system for the treatment of parathion-contaminated water. PMID:16312950

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

    PubMed

    Jang, JaeMyung; Kwon, TaeYub; Kim, KyoHan

    2008-10-01

    For an application as biomedical materials of high performance with a good biocompatibility, the TiO2 nanotube-type oxide film on Ti substrate has been fabricated by electrochemical method, and the effects of surface characteristics of TiO2 naotube layer have been investigated. The surface morphology of TiO2 nanotube layer depends on factors such as anodizing time, current density, and electrolyte temperature. Moreover, the cell and pore size gradually were increased with the passage of anodizing time. X-ray diffraction (XRD) results indicated that the TiO2 nanotube layer formed in acidic electrolytes was mainly composed of anatase structure containing rutile. From the analysis of chemical states of TiO2 nanotube layer using X-ray photoelectron spectroscopy (XPS), Ti2p, P2p and O1s were observed in the nanotubes layer, which were penetrated from the electrolyte into the oxide layer during anodic process. The incorporated phosphate species were found mostly in the forms of HPO4-, PO4-, and PO3-. From the result of biological evaluation in simulated body fluid (SBF) the TiO2 nanotube layer was effective for bioactive property. PMID:19198362

  1. 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.

  2. Enhanced photoelectrochemical performance by synthesizing CdS decorated reduced TiO2 nanotube arrays.

    PubMed

    Zhang, Qian; Wang, Ling; Feng, Jiangtao; Xu, Hao; Yan, Wei

    2014-11-14

    The efficient utilization of solar spectrum and photo-induced charge transport are critical aspects in improving the light conversion efficiency of solar cells and hydrogen generation. In this work, reduced TiO2 nanotube arrays with CdS decoration were fabricated through the simple cathodic polarization of annealed TiO2 nanotube arrays followed by the chemical deposition of CdS nanoparticles. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy confirmed the successful fabrication of the target material. UV-visible diffuse reflectance spectra showed a Burstein-Moss shift for reduced TiO2 NTs and a red shift of the absorption edge towards ca. 563 nm for CdS-decorated R-TiO2 NTs. Cyclic voltammetry and impedance spectra together demonstrate the decreased charge transport resistance for reduced TiO2 NTs. Under the excitation of monochromatic light at 420 nm, the proposed CdS-decorated reduced TiO2 NTs exhibit the maximum IPCE value of 30.12% in 1 M Na2SO3 electrolyte, which is almost twice higher than that achieved on CdS-decorated pristine TiO2 NTs. Therefore, the results here highlight the significance of charge transport in the light conversion process. The enhanced charge transport properties are ascribed to the increased number of electrons, which is brought about by the lattice oxygen vacancies (Ti(3+)) during the cathodic polarization. PMID:25265452

  3. Electrically polarized micro-arc oxidized TiO2 coatings with enhanced surface hydrophilicity.

    PubMed

    Ma, Chufan; Nagai, Akiko; Yamazaki, Yuko; Toyama, Takeshi; Tsutsumi, Yusuke; Hanawa, Takao; Wang, Wei; Yamashita, Kimihiro

    2012-02-01

    The use of micro-arc oxidation titania (MAO TiO2) coatings to modify titanium surfaces improves the biocompatibility of implant surfaces. To obtain hydrophilic MAO TiO2 coating surfaces electric polarization, which induces surface electric fields in the materials and produces surface charges, was performed in this study. Electric polarization of the MAO TiO2 coatings was confirmed by measuring the thermally stimulated depolarization current. After electric polarization treatment the MAO TiO2 coatings did not exhibit any obvious changes in surface roughness, morphology, or phase components. X-ray photoelectron spectroscopy results indicated that electric polarization resulted in oxidation of the cathodic-faced surfaces and reduction of the anodic-faced surfaces. This result suggests that the existence of a concentration gradient of oxide ions/oxygen vacancies produced the stored space charge in the coatings. Reduction of the deionized water contact angle on the polarized MAO TiO2 surfaces was maintained for longer periods compared with the non-polarized surface. Our study demonstrated that metastable electric fields across the MAO TiO2 coating produced by electric polarization made it durably wettable by reducing the interfacial surface tension between the material and water. PMID:21971419

  4. 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

  5. Preparation and tribological properties of stearic acid-modified hierarchical anatase TiO 2 microcrystals

    NASA Astrophysics Data System (ADS)

    Qian, Jianhua; Yin, Xiangyu; Wang, Ning; Liu, Lin; Xing, Jinjuan

    2012-01-01

    Hierarchical TiO2 microcrystals were synthesized through a facile solvothermal method. X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements were used to characterize the structure of the as-prepared samples. The results indicated that the synthesized hierarchical titania (TiO2) microspheres were composed of numerous anatase phase TiO2 particles. The as-prepared samples were chemically modified with stearic acid to improve their dispersion in oil. Fourier transmission infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA) were carried out to evaluate the characteristics of the modified TiO2 microcrystals. The tribological properties of the modified TiO2 microcrystals as additives of liquid paraffin were studied by a four-ball tester, and the results showed that they could significantly improve anti-wear performance, friction-reduction property and load-carrying capacity of liquid paraffin. These advantages make the modified TiO2 microcrystals promising for green lubricating oil additives.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. Composite WO3/TiO2 nanostructures for high electrochromic activity

    DOE PAGESBeta

    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

  11. [Fluorescence spectra and quantum yield of TiO2 nanocrystals synthesized by alcohothermal method].

    PubMed

    Song, Cui-Hong; Li, Yan-Ting; Li, Jing; Wei, Yong-Ju; Hu, Yu-Zhu; Wei, Yu

    2008-01-01

    Fluorescence spectra and fluorescence quantum yield of TiO2 nanocrystals were studied. Using tetra n-butyl titanate as a starting material, a facile alcohothermal technique was used to synthesize TiO2 nanocrystals. As can be seen from the transmittance electron microscopy (TEM) image, TiO2 nanocrystals with a relatively uniform particle size distribution of < 10 nm are present in the transparent sol. The transparent sol presents a strong stable fluorescence emission with a maximum at 450 nm, which is greatly dependent on the size quantization effects, defect energy level and the surface state of TiO2 nanocrystals. The quantum yield (gamma) of TiO2 was determined by the relative comparison procedure, using freshly prepared analytical purity quinine sulfate in 0.05 mol x L(-1) H2SO4 as a relative quantum yield standard. The emission quantum yield of TiO2 nanocrystals prepared in alcoholic media was calculated to be about 0.20 at wavelengths ranging from 330 to 370 nm, which was much higher than the values reported in previous works. So, it is supposed that nano-TiO2 will be applied as a potential quantum dots fluorescence probe in biological analysis. PMID:18422145

  12. 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.

  13. 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).

  14. Methanol Conversion into Dimethyl Ether on the Anatase TiO2(001) Surface.

    PubMed

    Xiong, Feng; Yu, Yan-Yan; Wu, Zongfang; Sun, Guanghui; Ding, Liangbing; Jin, Yuekang; Gong, Xue-Qing; Huang, Weixin

    2016-01-11

    Exploring reactions of methanol on TiO2 surfaces is of great importance in both C1 chemistry and photocatalysis. Reported herein is a combined experimental and theoretical calculation study of methanol adsorption and reaction on a mineral anatase TiO2(001)-(1×4) surface. The methanol-to-dimethyl ether (DME) reaction was unambiguously identified to occur by the dehydration coupling of methoxy species at the fourfold-coordinated Ti(4+) sites (Ti(4c)), and for the first time confirms the predicted higher reactivity of this facet compared to other reported TiO2 facets. Surface chemistry of methanol on the anatase TiO2(001)-(1×4) surface is seldom affected by co-chemisorbed water. These results not only greatly deepen the fundamental understanding of elementary surface reactions of methanol on TiO2 surfaces but also show that TiO2 with a high density of Ti(4c) sites is a potentially active and selective catalyst for the important methanol-to-DME reaction. PMID:26593777

  15. Doping mode, band structure and photocatalytic mechanism of B-N-codoped TiO 2

    NASA Astrophysics Data System (ADS)

    Yuan, Jixiang; Wang, Enjun; Chen, Yongmei; Yang, Wensheng; Yao, Jianghong; Cao, Yaan

    2011-06-01

    The photocatalyst B and N codoped TiO 2 (B-N-TiO 2) was prepared via the sol-gel method by using boric acid and ammonia as B and N precursors. The doping mode, band structure and photocatalytic mechanism of B-N-TiO 2 were investigated well and elucidated in detail. B-N-TiO 2 showed the narrowed band gap and thus extended the optical absorption due to interstitial N and [NOB] species in the TiO 2 crystal lattice. The coexistence of interstitial N and [NOB] species in the TiO 2 crystal lattice and surface NO x species allowed the more efficient utilization of visible light. Simultaneously, interstitial [NOB] and N species and surface B 2O 3 and NO x species facilitated the separation of photo generated electrons and holes and suppress their recombination effectively. Hence, B-N-TiO 2 showed a higher photocatalytic activity than pure TiO 2, N-doped TiO 2 (N-TiO 2) and B-doped TiO 2 (B-TiO 2) under both UV and visible light irradiation.

  16. Modulation of protein behavior through light responses of TiO2 nanodots films

    NASA Astrophysics Data System (ADS)

    Cheng, Kui; Hong, Yi; Yu, Mengfei; Lin, Jun; Weng, Wenjian; Wang, Huiming

    2015-08-01

    In this work, the behavior of protein molecules adsorbed on TiO2 nanodots films are modulated through the light responses of the nanodots. TiO2 nanodots films are first prepared through phase separation induced self assembly. Then, bovine serum albumin (BSA) is adsorbed on TiO2 nanodots films and exposed to ultraviolet (365 nm) illumination. It is found the conformation of surface-bound BSA molecules changes with ultraviolet illumination. Moreover, the BSA molecules conjugate to the surface-bound molecules, which are in the overlayer, are released. The reason is ascribed to that TiO2 nanodots absorb ultraviolet and result in the increase of surface hydroxyl groups on nanodots. Such increase further leads to intensified attraction of -NH3 groups in the surface-bound BSA molecules. That not only changes the conformation of the surface-bound BSA molecules, but also weaken the conjugation between surface-bound molecules and other BSA molecules in the overlayer. Eventually, the overlayer of BSA molecules is released. It is believed that such protein conformation variation and release behavior induced through light responses of TiO2 nanodots are crucial in understanding the biomedical performance of TiO2 nanostructures. Also, it could be widely utilized in tailoring of the materials-protein interactions.

  17. A facile method to synthesize the photocatalytic TiO2/montmorillonite nanocomposites with enhanced photoactivity

    NASA Astrophysics Data System (ADS)

    Chen, Daimei; Zhu, Honglei; Wang, Xue

    2014-11-01

    A new method for immobilizing nano-scaled TiO2 on the surface of montmorillonite (Mt) clay has been developed. First, cationic surfactants were introduced into the Mt galleries through ion exchange and physical adsorption processes. Next a titanium precursor with negative charges was allowed to hydrolyze and condense around the nature clay to form meso-phase assemblies on the external and internal surface of the Mt. After the removal of the surfactant, a highly porous TiO2 pillared clay with mesopores was formed. The cationic surfactant has a templating role, which not only tailored the formation of TiO2 but also controlled the TiO2 content in the composite. The photocatalytic performances of these new porous materials were evaluated by using methylene blue degradation. The photocatalytic activity of these TiO2 composite is higher than that of P25 although TiO2 only accounts for about one-third of the sample's mass in the composite samples.

  18. 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.

  19. 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

  20. 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

  1. Controlled synthesis of hierarchical TiO2 nanoparticles on glass fibres and their photocatalytic performance.

    PubMed

    Chen, Lin; Yang, Sudong; Mäder, Edith; Ma, Peng-Cheng

    2014-09-01

    This paper reports the synthesis of novel photocatalysts consisting of TiO2 nanoparticles and glass fibres (GF) using a two-step process. The method involves the hydrolysis of titanium tetrachloride in the presence of GF and a following hydrothermal process under alkaline conditions. Various techniques are employed to characterize the morphology, structure and crystallinity of TiO2 on the fibre surface. The results show that depending on the experiment setups, TiO2 nanoparticles exhibit spherical or flake-like morphology, forming characteristic hierarchical structures along with flexible GF. Flake-like TiO2/GF exhibits much enhanced photocatalytic activity thanks to the large surface area and the hetero-junction of anatase and TiO2-B phases observed in its structure. An interesting observation is that the alkali treatment of GF leads to the formation of porous structures on the fibre surface, facilitating the adsorption-concentration-promoted photocatalytic process. The removal ratio of the organic dye by employing TiO2/GF remains more than 80% after six cyclic runs, showing the reusability of photocatalysts in real application. The novelty of this work lies in the synergy arising from materials with unique morphologies, structures and availabilities as well as capabilities in separating photogenerated electron-hole pairs, which have not been specifically considered previously in photocatalytic semiconductors. PMID:25011616

  2. Photochemical grafting and patterning of biomolecular layers onto TiO2 thin films.

    PubMed

    Li, Bo; Franking, Ryan; Landis, Elizabeth C; Kim, Heesuk; Hamers, Robert J

    2009-05-01

    TiO2 thin films are highly stable and can be deposited onto a wide variety of substrate materials under moderate conditions. We demonstrate that organic alkenes will graft to the surface of TiO2 when illuminated with UV light at 254 nm and that the resulting layers provide a starting point for the preparation of DNA-modified TiO2 thin films exhibiting excellent stability and biomolecular selectivity. By using alkenes with a protected amino group at the distal end, the grafted layers can be deprotected to yield molecular layers with exposed primary amino groups that can then be used to covalently link DNA oligonucleotides to the TiO2 surface. We demonstrate that the resulting DNA-modified surfaces exhibit excellent selectivity toward complementary versus noncomplementary target sequences in solution and that the surfaces can withstand 25 cycles of hybridization and denaturation in 8.3 M urea with little or no degradation. Furthermore, the use of simple masking methods provides a way to directly control the spatial location of the grafted layers, thereby providing a way to photopattern the spatial distribution of biologically active molecules to the TiO2 surfaces. Using Ti films ranging from 10 to 100 nm in thickness allows the preparation of TiO2 films that range from highly reflective to almost completely transparent; in both cases, the photochemical grafting of alkenes can be used as a starting point for stable surfaces with good biomolecular recognition properties. PMID:20355886

  3. A facile solvothermal route to photocatalytically active nanocrystalline anatase TiO 2 from peroxide precursors

    NASA Astrophysics Data System (ADS)

    Perera, Sujith; Gillan, Edward G.

    2008-07-01

    This report describes the rapid synthesis of nanocrystalline powders of anatase TiO 2 using exothermic metathesis (exchange) reactions moderated by a high-boiling hexadecane solvent. One reagent, TiBr 4, dissolved in hexadecane interacts with a dispersion of Na 2O 2 at elevated temperatures to produce TiO 2 and NaBr. Reactions occur within a few hours near the reflux point of hexadecane (bp 287 °C). The isolated crystalline TiO 2 powders are either anatase or anatase/brookite mixtures, depending on how quickly the reagents were heated to reflux. Locally exothermic solution-surface events occur and are likely responsible for crystalline TiO 2 formation directly from the solvothermal reaction without need for any post-reaction annealing. Rapidly synthesized nanocrystalline TiO 2 exhibits elongated nanostructural features. Results from variations in reaction conditions and use of other halide and oxygen reagents are also discussed. The isolated TiO 2 powders have organic surface coatings, but brief air calcination yields water-dispersible titania nanoparticulate powders that function as active UV photocatalysts for methylene blue solution oxidation.

  4. 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.

  5. 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

  6. 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.

  7. TiO2 Nanoparticles Produced by Electric-Discharge-Nanofluid-Process as Photoelectrode of DSSC

    NASA Astrophysics Data System (ADS)

    Chen, Sih-li; Su, Hung-ting; Chang, Ho; Jwo, Ching-song; Feng, Hsiao Ju

    2010-04-01

    Self-made TiO2 nanoparticles were used as photoelectrode material of dye sensitized solar cell. The TiO2 thin film coats through spreading nanoparticles evenly onto the ITO glass via self-made spin-heat platform, and then TiO2 thin film is soaked in the dye N-719 more than 12 h to prepare the photoelectrode device. The TiO2 nanoparticles produced by electric-discharge-nanofluid-process have premium anatase crystal property, and its diameter can be controlled within a range of 20-50 nm. The surface energy zeta potential of nanofluid is from -22 mV to -28.8 mV, it is a stable particle suspension in the deionized water. A trace of surfactant Triton X-100 put upon the surface of ITO glass can produce a uniform and dense TiO2 thin film and heating up the spin platform to 200 °C is able to eliminate mixed surfactant. Self-made TiO2 film presents excellent dye absorption performance and even doesn't need heat treatment procedure to enhance essential property. Results of energy analysis show the thicker film structure will increase the short-circuit current density that causes higher conversion efficiency. But, as the film structure is large and thick, both the open-circuit voltage and fill factor will decline gradually to lead bad efficiency of dye-sensitized solar cell.

  8. 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. PMID:23240759

  9. 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. PMID:23901537

  10. On the photocatalytic properties of elongated TiO2 nanoparticles for phenol degradation and Cr(VI) reduction.

    PubMed

    Mu, Rongxin; Xu, Zhaoyi; Li, Liyuan; Shao, Yun; Wan, Haiqing; Zheng, Shourong

    2010-04-15

    Elongated TiO(2) nanoparticles with high aspect ratio have specific advantages in separation processes. In this study, TiO(2) nanofiber was prepared via a hydrothermal reaction, and TiO(2) nanoparticles with varied structural properties were obtained using hydrothermal and calcination post-treatments. Photocatalytic phenol degradation and Cr(VI) reduction over these catalysts was investigated. Results showed that hydrothermally prepared TiO(2) nanofiber consisted of titanate with high aspect ratio. Calcining the as-prepared TiO(2) nanofiber at 400 and 600 degrees C led to the crystalline phase transformation from titanate to TiO(2)-B and to the presence of mixed crystalline phases composed of TiO(2)-B and anatase. In contrast, hydrothermal post-treatment results in the generation of pure anatase TiO(2) nanoparticles. For photocatalytic phenol degradation, calcining the as-prepared TiO(2) nanofiber resulted in an enhanced catalytic activity, whereas TiO(2) nanoparticles obtained by calcination post-treatment showed lower catalytic activities for photocatalytic Cr(VI) reduction compared to as-prepared TiO(2) nanofiber. TiO(2) nanofiber modified using the hydrothermal post-treatment, however, exhibited the highest catalytic activity among TiO(2) nanoparticles examined for both photocatalytic phenol degradation and Cr(VI) reduction. Furthermore, TiO(2) nanoparticles obtained by hydrothermal post-treatment showed the best sedimentation efficiency, highlighting its prominent potential as a readily separable and recoverable photocatalyst. PMID:19969418

  11. Improved lithium storage properties of electrospun TiO2 with tunable morphology: from porous anatase to necklace rutile

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Wang, Haiying; Zhou, Qiwen; Kong, Mengqi; Ye, Haitao; Yang, Gang

    2013-10-01

    Three-dimensional TiO2 with tunable morphology and crystalline phase was successfully prepared by the electrospinning technique and subsequent annealing. Porous-shaped anatase TiO2, cluster-shaped anatase TiO2, hierarchical-shaped rutile (minor) TiO2 and nano-necklace rutile (major) TiO2 were achieved at 500, 600, 700 and 800 °C, respectively. The mechanism of the formation of these tailored morphologies and crystallinity was investigated. Lithium insertion properties were evaluated by galvanostatic and potentiostatic modes in half-cell configurations. By combining the large surface area, open mesoporosity and stable crystalline phase, the porous-shaped anatase TiO2 exhibited the highest capacity, best rate and cycling performance among the four samples. The present results demonstrated the usefulness of three-dimensional TiO2 as an anode for lithium storage with improved electrode performance.Three-dimensional TiO2 with tunable morphology and crystalline phase was successfully prepared by the electrospinning technique and subsequent annealing. Porous-shaped anatase TiO2, cluster-shaped anatase TiO2, hierarchical-shaped rutile (minor) TiO2 and nano-necklace rutile (major) TiO2 were achieved at 500, 600, 700 and 800 °C, respectively. The mechanism of the formation of these tailored morphologies and crystallinity was investigated. Lithium insertion properties were evaluated by galvanostatic and potentiostatic modes in half-cell configurations. By combining the large surface area, open mesoporosity and stable crystalline phase, the porous-shaped anatase TiO2 exhibited the highest capacity, best rate and cycling performance among the four samples. The present results demonstrated the usefulness of three-dimensional TiO2 as an anode for lithium storage with improved electrode performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02819d

  12. 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. PMID:24040965

  13. 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

  14. 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

  15. Preparation and Characterization of SiO 2/TiO 2 composite microspheres with microporous SiO 2 core/mesoporous TiO 2 shell

    NASA Astrophysics Data System (ADS)

    Zhao, Li; Yu, Jiaguo; Cheng, Bei

    2005-06-01

    SiO 2/TiO 2 composite microspheres with microporous SiO 2 core/mesoporous TiO 2 shell structures were prepared by hydrolysis of titanium tetrabutylorthotitanate (TTBT) in the presence of microporous silica microspheres using hydroxypropyl cellulose (HPC) as a surface esterification agent and porous template, and then dried and calcined at different temperatures. The as-prepared products were characterized with differential thermal analysis and thermogravimetric (DTA/TG), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption. The results showed that composite particles were about 1.8 μm in diameter, and had a spherical morphology and a narrow size distribution. Uniform mesoporous titania coatings on the surfaces of microporous silica microspheres could be obtained by adjusting the HPC concentration to an optimal concentration of about 3.2 mmol L -1. The anatase and rutile phase in the SiO 2/TiO 2 composite microspheres began to form at 700 and 900 °C, respectively. At 700 °C, the specific surface area and pore volume of the SiO 2/TiO 2 composite microspheres were 552 and 0.652 mL g -1, respectively. However, at 900 °C, the specific surface area and pore volume significantly decreased due to the phase transformation from anatase to rutile.

  16. 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. PMID:18767641

  17. 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. PMID:27241615

  18. Plasmonic photocatalysis properties of Au nanoparticles precipitated anatase/rutile mixed TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Wen, Yan; Liu, Bitao; Zeng, Wei; Wang, Yuhua

    2013-09-01

    Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail.Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03024e

  19. 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.

  20. 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. PMID:25905566

  1. 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

  2. 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

  3. Novel TiO2-Pt@SiO2 nanocomposites with high photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Wu, Hao-Shuai; Sun, Ling-Dong; Zhou, Huan-Ping; Yan, Chun-Huan

    2012-05-01

    This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the nanocomposites but also prevent their aggregation during the photocatalytic reactions, which is highly important for the good durability of the photocatalyst. This strategy is simple, albeit efficient, and can be extended to the synthesis of other composites of noble metals. It has opened a new window for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest.This article reports a facile and controllable two-step method to construct TiO2-Pt@SiO2 nanocomposites. TiO2 nanoparticles (NPs), with small size and high surface energy, were synthesized by a solvothermal reaction process. The TiO2-Pt@SiO2 nanocomposites were fabricated by a reverse micro-emulsion method. SiO2 shell coated NPs were adopted for further photocatalytic reaction. Because of their small size and high surface energy, TiO2@SiO2 and TiO2-Pt@SiO2 nanocomposites show higher photocatalytic activity than commercial Degussa P25. Compared with TiO2@SiO2, TiO2-Pt@SiO2nanocomposites have improved photocatalytic activity due to the Pt induced spatial separation of electrons and holes. The silica shells not only maintain the structure of the nanocomposites but also prevent their aggregation during the photocatalytic reactions, which is highly important for the good durability of the photocatalyst. This strategy is simple, albeit efficient, and can be extended to the synthesis of other composites of noble metals. It has opened a new window for the construction of hetero-nanocomposites with high activity and durability, which would serve as excellent models in catalytic systems of both theoretical and practical interest. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30523b

  4. 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

    2016-06-01

    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.

  5. Nanostructured AgBr loaded TiO2: An efficient sunlight active photocatalyst for degradation of Reactive Red 120.

    PubMed

    Velmurugan, Rengasamy; Sreedhar, Bojja; Swaminathan, Meenakshisundaram

    2011-01-01

    The AgBr loaded TiO2 catalyst was prepared by a feasible approach with AgBr and tetraisopropyl orthotitanate and characterized by BET surface area measurement, diffuse reflectance spectra (DRS), scanning electron microscope (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscope (AFM) analysis. The results of characterization reveal that AgBr loaded TiO2 has a nanostructure. Formation of the nanostructure in AgBr loaded TiO2 results in substantial shifting of the absorption edge of TiO2 to red and enhancement of visible light absorption. Electrochemical impedance spectroscopy measurements reveal that AgBr loaded TiO2 has a higher photoconductivity than prepared TiO2 due to higher separation efficiency of electron-hole pairs. Cyclic voltammetric studies reveal enhanced conductivity in AgBr loaded TiO2, which causes an increase in its photocatalytic activity. AgBr loaded TiO2 exhibited a higher photocatalytic activity than TiO2-P25 and prepared TiO2 in the photodegradation of Reactive Red 120 (RR 120). PMID:21801445

  6. 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. PMID:24734539

  7. Nanostructured AgBr loaded TiO2: An efficient sunlight active photocatalyst for degradation of Reactive Red 120

    PubMed Central

    2011-01-01

    The AgBr loaded TiO2 catalyst was prepared by a feasible approach with AgBr and tetraisopropyl orthotitanate and characterized by BET surface area measurement, diffuse reflectance spectra (DRS), scanning electron microscope (SEM), energy dispersive spectra (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM) and atomic force microscope (AFM) analysis. The results of characterization reveal that AgBr loaded TiO2 has a nanostructure. Formation of the nanostructure in AgBr loaded TiO2 results in substantial shifting of the absorption edge of TiO2 to red and enhancement of visible light absorption. Electrochemical impedance spectroscopy measurements reveal that AgBr loaded TiO2 has a higher photoconductivity than prepared TiO2 due to higher separation efficiency of electron-hole pairs. Cyclic voltammetric studies reveal enhanced conductivity in AgBr loaded TiO2, which causes an increase in its photocatalytic activity. AgBr loaded TiO2 exhibited a higher photocatalytic activity than TiO2-P25 and prepared TiO2 in the photodegradation of Reactive Red 120 (RR 120). PMID:21801445

  8. 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

  9. Effect of calcined atmosphere on the photocatalytic activity of P-doped TiO2

    NASA Astrophysics Data System (ADS)

    Xia, Yue; Jiang, Yinshan; Li, Fangfei; Xia, Maosheng; Xue, Bing; Li, Yanjuan

    2014-01-01

    Titanium dioxide doped with phosphorus was synthesized by the sol-gel method with H3PO4 addition. The samples were calcined at different temperatures under different atmospheres, in order to affect the Tisbnd O combination behavior in P-doped TiO2. The physicochemical properties of the prepared samples were investigated using TG-DTA, XRD, FTIR, XPS, TEM and UV-vis. The photocatalytic activity was evaluated by degradation of methyl orange (MO) dye under UV and visible-light irradiation. The results show that P-doped TiO2 calcined in different thermal atmosphere reveals entirely different performances. The XRD and UV-vis analysis reveal that the effect of P species in TiO2 is increased by calcining in reducing atmosphere. Further photocatalytic experiments also display that P-doped TiO2 calcined under carbothermal reduction atmosphere (R-PT) exhibits higher photocatalytic activity than that calcined in air (A-PT). The XPS results confirms that the calcining atmosphere changes the distribution concentration of surface and interface species in P-doped TiO2, such as surface oxygen and Ti3+ sites, resulting in the improved photocatalytic activity and enhanced reutilization performance of R-PT. Further mechanism study illustrates that the promoting photocatalytic activity of P-doped TiO2 are ascribed to the formation of Ti3+ sites rather than exceeding oxygen on the surface. And the carbothermal process helps to reserve these Ti3+ sites during high temperature calcination, resulting in the increased photocatalytic activity of P-doped TiO2, especially when the doping level of P species is relative low.

  10. 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. PMID:24123999

  11. Bolometric properties of reactively sputtered TiO2-x films for thermal infrared image sensors

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Kang, In-Ku; Shin, Young Bong; Lee, Hee Chul

    2015-09-01

    A heat-sensitive layer (TiO2-x ) was successfully deposited by RF reactive magnetron sputtering for infrared (IR) image sensors at different relative mass flow of oxygen gas (R O2) levels. The deposition rate was decreased with an increase in the percentage of R O2 from 3.4% to 3.7%. TiO2-x samples deposited at room temperature exhibited amorphous characteristics. Oxygen deficiency causes a change in the oxidation state and is assumed to decrease the Ti4+ component on the surfaces of TiO2-x films. The oxygen stoichiometry (x) in TiO2-x films decreased from 0.35 to 0.05 with increasing the R O2 level from 3.4% to 3.7%, respectively. In TiO2-x -test-patterned samples, the resistivity decreased with the temperature, confirming the typical semiconducting property. The bolometric properties of the resistivity, temperature coefficient of resistance (TCR), and the flicker (1/ f) noise parameter were determined at different x values in TiO2-x samples. The rate of TCR dependency with regard to the 1/ f noise parameter is a universal bolometric parameter (β), acting as the dynamic element in a bolometer. It is high when a sample has a relatively low resistivity (0.82 Ω·cm) and a lower 1/ f noise parameter (3.16   ×   10-12). The results of this study indicate that reactively sputtered TiO2-x is a viable bolometric material for uncooled IR image sensor devices.

  12. Removal of Cr(VI) and humic acid by using TiO2 photocatalysis.

    PubMed

    Yang, Jae-Kyu; Lee, Seung-Mok

    2006-06-01

    The removal efficiencies of Cr(VI) and HA, using a TiO(2)-mediated photocatalytic process, were investigated with variations in the pH, TiO(2) dosage and Cr(VI)/HA ratio. During the photocatalytic reaction, the total removal of Cr(VI) occurred through adsorption onto TiO(2), as well as its reduction to Cr(III). However, oxidation and adsorption were identified as important removal processes for the treatment of HA. Due to the anionic type adsorption onto TiO(2) and its acid-catalyzed photocatalytic reduction, the removal of Cr(VI) decreased with increasing pH, while that of HA increased with increasing pH. The TiO(2) dosage was also an important parameter for the removal of Cr(VI). As the TiO(2) dosage was increased to 2.5 g l(-1), the removal of Cr(VI) was continuously enhanced, but decreased at dosages above 3 g l(-1) due to the increased blockage of the incident UV light used for the photocatalytic reaction. The removal of Cr(VI) was greatly enhanced when the system contained both HA and Cr(VI) compared to Cr(VI) alone. Also, the removal of HA was greatly enhanced when the system contained both HA and Cr(VI) compared to HA alone. The removal of Cr(VI) was continuously enhanced as the HA concentration gradually increased; however, no further increase was observed above 20 mg l(-1) HA due to the increased absorption of the UV light. This result supports that the photocatalytic reaction, with illuminated TiO(2), could be applied to more effectively treat wastewater containing both Cr(VI) and HA than that containing a single species only. PMID:16325231

  13. 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. PMID:16173589

  14. Cytotoxic and inflammatory responses of TiO2 nanoparticles on human peripheral blood mononuclear cells.

    PubMed

    Kongseng, Supunsa; Yoovathaworn, Krongtong; Wongprasert, Kanokpan; Chunhabundit, Rodjana; Sukwong, Patinya; Pissuwan, Dakrong

    2016-10-01

    Titanium dioxide nanoparticles (TiO2 -NPs) have been widely used in many applications. Owing to their nanoscale size, interactions between cells and NPs have been expansively investigated. With the health concerns raised regarding the adverse effects of these interactions, closer examination of whether TiO2 -NPs can induce toxicity towards human cells is greatly needed. Therefore, in this study, we investigated the cytotoxicity of TiO2 -NPs towards human blood cells (peripheral blood mononuclear cells [PBMCs]) in serum-free medium, for which there is little information regarding the cytotoxic effects of TiO2 -NPs. Our results provide evidence that PBMCs treated with TiO2 -NPs (at concentrations ≥25 μg ml(-1) ) for 24 h significantly reduced cell viability and significantly increased production of toxic mediators such as reactive oxygen species and inflammatory response cytokines such as interleukin-6 and tumor necrosis factor-α (P < 0.05). Cell apoptosis induction also occurred at these concentrations. Significant expressions of cyclooxygenase-2 and interleukin-1β were also observed in PBMCs treated with TiO2 -NPs at concentrations ≥125 μg ml(-1) . Our data presented here clearly indicate that the concentration of TiO2 -NPs (at size ~26.4 ± 1.2 nm) applied to human blood cells has a strong impact on cytotoxic induction. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27225715

  15. TiO2@Carbon Photocatalysts: The Effect of Carbon Thickness on Catalysis.

    PubMed

    Zhang, Jianming; Vasei, Mitra; Sang, Yuanhua; Liu, Hong; Claverie, Jerome P

    2016-01-27

    Nanocomposites composed of TiO2 and carbon materials (C) are widely popular photocatalysts because they combine the advantages of TiO2 (good UV photocatalytic activity, low cost, and stability) to the enhanced charge carrier separation and lower charge transfer resistance brought by carbon. However, the presence of carbon can also be detrimental to the photocatalytic performance as it can block the passage of light and prevent the reactant from accessing the TiO2 surface. Here using a novel interfacial in situ polymer encapsulation-graphitization method, where a glucose-containing polymer was grown directly on the surface of the TiO2, we have prepared uniform TiO2@C core-shell structures. The thickness of the carbon shell can be precisely and easily tuned between 0.5 and 8 nm by simply programming the polymer growth on TiO2. The resulting core@shell TiO2@C nanostructures are not black and they possess the highest activity for the photodegradation of organic compounds when the carbon shell thickness is 1-2 nm, corresponding to ∼3-5 graphene layers. Photoluminescence and photocurrent generation tests further confirm the crucial contribution of the carbon shell on charge carrier separation and transport. This in situ polymeric encapsulation approach allows for the careful tuning of the thickness of graphite-like carbon, and it potentially constitutes a general and efficient route to prepare other oxide@C catalysts, which can therefore largely expand the applications of nanomaterials in catalysis. PMID:26716463

  16. 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.

  17. 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.

  18. 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.

  19. 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%.

  20. 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.

  1. Thermal Behavior and Phase Transformation of TiO2 Nanocrystallites Prepared by a Coprecipitation Route

    NASA Astrophysics Data System (ADS)

    Yeh, Shang-Wei; Chen, Yen-Ling; Hsi, Chi-Shiung; Ko, Horng-Huey; Wang, Moo-Chin

    2014-01-01

    TiO2 freeze-dried precursor powders were synthesized using a coprecipitation route that includes titanium tetrachloride (TiCl4) as initial material prepared at 348 K (75 °C) and pH 7. Differential scanning calorimetry/thermogravimetry (DSC/TG), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) and high resolution TEM were utilized to characterize the thermal behavior and phase transformation of the TiO2 freeze-dried precursor powders after calcination. The main compound of the TiO2 freeze-dried precursor powders was TiO2·H2O based on a TG analysis conducted at a heating rate of 20 K (20 °C)/min. The anatase TiO2 (a-TiO2) first appeared at 473 K (200 °C), then from a-TiO2 transformed to rutile TiO2 (r-TiO2) at 773 K (500 °C). The activation energy of a-TiO2 formation from TiO2 freeze-dried precursor powders was 242.4 ± 33.9 kJ/mol, whereas, the activation energy of phase transformation from a-TiO2 to r-TiO2 was 267.5 ± 19.1 kJ/mol. The crystallite size of a-TiO2 grew from 3.5 to 23.2 nm when raising the calcination temperature from 473 K to 873 K (200 °C to 600 °C). In addition, the crystallite size of r-TiO2 increased from 17.4 to 48.1 nm when calcination temperature increased from 773 K to 1073 K (500 °C to 800 °C).

  2. Preparation and characterization of TiO2 barrier layers for dye-sensitized solar cells.

    PubMed

    Zheng, Yichen; Klankowski, Steven; Yang, Yiqun; Li, Jun

    2014-07-01

    A TiO2 barrier layer is critical in enhancing the performance of dye-sensitized solar cells (DSSCs). Two methods to prepare the TiO2 barrier layer on fluorine-doped tin dioxide (FTO) surface were systematically studied in order to minimize electron-hole recombination and electron backflow during photovoltaic processes of DSSCs. The film structure and materials properties were correlated with the photovoltaic characteristics and electrochemical properties. In the first approach, a porous TiO2 layer was deposited by wet chemical treatment of the sample with TiCl4 solution for time periods varying from 0 to 60 min. The N719 dye molecules were found to be able to insert into the porous barrier layers. The 20 min treatment formed a nonuniform but intact TiO2 layer of ∼100-300 nm in thickness, which gave the highest open-circuit voltage VOC, short-circuit photocurrent density JSC, and energy conversion efficiency. But thicker TiO2 barrier layers by this method caused a decrease in JSC, possibly limited by lower electrical conductance. In the second approach, a compact TiO2 barrier layer was created by sputter-coating 0-15 nm Ti metal films on FTO/glass and then oxidizing them into TiO2 with thermal treatment at 500 °C in the air for 30 min. The dye molecules were found to only attach at the outer surface of the barrier layer and slightly increased with the layer thickness. These two kinds of barrier layer showed different characteristics and may be tailored for different DSSC studies. PMID:24927111

  3. Spectral characteristics and photosensitization of TiO2 nanoparticles in reverse micelles by perylenes.

    PubMed

    Hernández, Laura I; Godin, Robert; Bergkamp, Jesse J; Llansola Portolés, Manuel J; Sherman, Benjamin D; Tomlin, John; Kodis, Gerdenis; Méndez-Hernández, Dalvin D; Bertolotti, Sonia; Chesta, Carlos A; Mariño-Ochoa, Ernesto; Moore, Ana L; Moore, Thomas A; Cosa, Gonzalo; Palacios, Rodrigo E

    2013-04-25

    We report on the photosensitization of titanium dioxide nanoparticles (TiO2 NPs) synthesized inside AOT (bis(2-ethylhexyl) sulfosuccinate sodium salt) reverse micelles following photoexcitation of perylene derivatives with dicarboxylate anchoring groups. The dyes, 1,7-dibromoperylene-3,4,9,10-tetracarboxy dianhydride (1), 1,7-dipyrrolidinylperylene-3,4,9,10-tetracarboxy dianhydride (2), and 1,7-bis(4-tert-butylphenyloxy)perylene-3,4,9,10-tetracarboxy dianhydride (3), have considerably different driving forces for photoinduced electron injection into the TiO2 conduction band, as estimated by electrochemical measurements and quantum mechanical calculations. Fluorescence anisotropy measurements indicate that dyes 1 and 2 are preferentially solubilized in the micellar structure, creating a relatively large local concentration that favors the attachment of the dye to the TiO2 surface. The binding process was followed by monitoring the hypsochromic shift of the dye absorption spectra over time for 1 and 2. Photoinduced electron transfer from the singlet excited state of 1 and 2 to the TiO2 conduction band (CB) is indicated by emission quenching of the TiO2-bound form of the dyes and confirmed by transient absorption measurements of the radical cation of the dyes and free carriers (injected electrons) in the TiO2 semiconductor. Steady state and transient spectroscopy indicate that dye 3 does not bind to the TiO2 NPs and does not photosensitize the semiconductor. This observation was rationalized as a consequence of the bulky t-butylphenyloxy groups which create a strong steric impediment for deep access of the dye within the micelle structure to reach the semiconductor oxide surface. PMID:23189921

  4. 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.

  5. Spectroscopic analyses on ROS generation catalyzed by TiO2, CeO2/TiO2 and Fe2O3/TiO2 under ultrasonic and visible-light irradiation

    NASA Astrophysics Data System (ADS)

    Zou, Mingming; Kong, Yumei; Wang, Jun; Wang, Qi; Wang, Zhiqiu; Wang, Baoxin; Fan, Ping

    2013-01-01

    In this work, the TiO2, CeO2/TiO2 and Fe2O3/TiO2 powders were irradiated, respectively, by ultrasound and visible-light, and the generation of reactive oxygen species (ROS) were estimated by the method of Oxidation-Extraction Photometry (OEP). That is, the 1,5-diphenyl carbazide (DPCI) can be oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed solvent of benzene and carbon tetrachloride. The DPCO extract liquor displays an obvious absorbance at 563 nm wavelength. In addition, some influencing factors, such as (ultrasonic or visible-light) irradiation time, catalyst addition amount and DPCI concentration, on the generation of ROS were also reviewed. The results indicated that the quantities of generated ROS increase with the increase of (ultrasonic or visible-light) irradiation time and catalyst addition amount. Moreover, the displayed quantities of ROS are also related with DPCI concentration. And then, several radical scavengers were used to determine the kinds of the generated ROS. At last, the researches on the sonocatalytic and photocatalytic degradation of several organic dyes have also been performed. It is wished that this paper might offer some important subjects for broadening the applications of sonocatalytic and photocatalytic technologies in future environment treatment.

  6. 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%). PMID:24071636

  7. 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

  8. 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.

  9. Photocatalitic Properties of Tio2 and ZnO Nanopowders / Tio2 un Zno Nanopulveru Fotokatalitiskās Īpašības

    NASA Astrophysics Data System (ADS)

    Grigorjeva, L.; Rikveilis, J.; Grabis, J.; Jankovica, Dz.; Monty, C.; Millers, D.; Smits, K.

    2013-08-01

    Photocatalytic activity of TiO2 and ZnO nanopowders is studied depending on the morphology, grain sizes and method of synthesizing. Photocatalysis of the prepared powders was evaluated by degradation of the methylene blue aqueous solution. Absorbance spectra (190-100 nm) were measured during exposure of the solution to UV light. The relationships between the photocatalytic activity and the particle size, crystal polymorph phases and grain morphology were analyzed. The photocatalytic activity of prepared TiO2 nanopowders has been found to depend of the anatase-to-rutile phase ratio. Comparison is given for the photocatalytic activity of ZnO nanopowders prepared by sol-gel and solar physical vapour deposition (SPVD) methods Darbā pētīta fotokatalīzes efektivitāte ar dažādām metodēm sintezētiem TiO2 and ZnO nanopulveriem, kuriem ir atšķirīga morfoloģija un grauda izmērs. Foto katalīzes process raksturots ar metilenzilā sagraušanu ūdens šķīdumā, to apstarojot ar UV gaismu. Analizēta fotokatalīzes efektivitātes atkarība no grauda izmēra, nanokristālu graudu morfoloģijas, TiO2 nanopulveru anatasa-rutīla fāžu svara attiecībām. Parādīts, ka fotokatalītiskā efektivitāte ir atšķirīga TiO2 nanopulveriem sintezētiem ar dažādām metodēm: sola-gēla un tvaicēšanu-kondensēšanu saules reaktorā. Salīdzināta fotokatalīzes efektivitāte ZnO un TiO2 nanopulveriem un secināts, ka ZnO nanopulveri ar tetrapodu morfoloģiju ir labs fotokatalizators

  10. 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

  11. 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.

  12. Structure and Formation Mechanism of Black TiO2 Nanoparticles

    DOE PAGESBeta

    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

  13. 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.

  14. Structure compatibility of TiO2 and SiO2 surfaces

    NASA Astrophysics Data System (ADS)

    Tokarský, Jonáš; Čapková, Pavla

    2013-11-01

    A simple method for the estimation of the most suitable mutual crystallographic orientations of TiO2 nanoparticles anchored on SiO2 substrate is presented in this work. Number of overlapping titanium and oxygen atoms creating atomic pairs can be used to quantify the structure compatibility. These atomic pairs are obtained directly from non-optimized TiO2 and SiO2 atomic planes. The descriptions of algorithms being implemented as scripts into the MATLAB environment in order to make the method more effective are also provided. This method can help with the selection of the most promising (h k l) planes of TiO2 and SiO2 adjacent surfaces and the outputs are in good agreement with results of molecular modeling of TiO2 nanoparticles anchored on SiO2 surfaces within the meaning of ability to determine the optimized models with the highest and the lowest TiO2-SiO2 adhesion energies. To the best of our knowledge, there is no other such simple and efficient method providing this information, which is very important for molecular modeling of nanoparticle-crystalline substrate systems.

  15. 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. PMID:17214486

  16. 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

  17. 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.

  18. Vibrational features of confined water in nanoporous TiO2 by Raman spectra

    NASA Astrophysics Data System (ADS)

    Xin, Gao; Qiang, Wang; Gang, Sun; Chen-Xi, Li; Lin, Hu

    2016-02-01

    Raman spectra of confined water adsorbed in nanoporous TiO2 are obtained in experiment. TiO2 samples with different pore diameters under different humidity conditions are investigated. The results indicate that the symmetric vibrational mode of water molecule is destroyed when relative humidity decreases. This indicates that the interaction between water molecules and surface of TiO2 becomes stronger when the distance between water molecules and surface turns smaller, and the interaction plays a major role in depressing the symmetric vibrational peak. The spectra of confined water in TiO2 and Vycor are compared. When filling fractions are the same, their spectra show distinctions no matter whether they are in partial filling condition or in full filling condition. The spectra of HDO confined in TiO2 with different filling fractions are compared with each other. There is no clear distinction among their vibrational peaks, and the peaks mainly relate to asymmetric vibration. Therefore, the interaction between water molecules and the wall of pore decouples the symmetric vibrational mode only, and the influences on asymmetric vibrational mode show little differences among different filling fractions. Project supported by the National Natural Science Foundation of China (Grant Nos. 11304049 and 11264006), the Guizhou Provincial Science and Technology Foundation, China (Grant No. J[2010]2132), and the Doctor Funds of Guizhou University, China (Grant No. [2012] 020).

  19. 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. PMID:26429596

  20. 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

  1. 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. PMID:26674237

  2. 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.

  3. 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

  4. Photoconductivity and stabilization of dopamine embedded in sol-gel TiO2 matrix

    NASA Astrophysics Data System (ADS)

    Prado-Prone, Gina; Valverde-Aguilar, Guadalupe; García-Macedo, Jorge; Vergara-Aragón, P.

    2012-09-01

    This work reports the synthesis of amorphous TiO2 matrix by sol-gel method at atmospheric conditions. DA was encapsulated in a TiO2 matrix to reduce its chemical instability. To TiO2/DA sample was added the 15C5 to diminish the oxidation process. The stabilization process was followed by absorption spectra, colour change and infrared spectroscopy. Oxidation processes of the DA were identified by the presence of DA-quinone and DA-chrome. The TiO2/DA complex retarded the oxidation process for 30 days, while the TiO2/DA/15C5 complex this period was extended for 47 days. Photoconductivity studies were performed on both kinds of samples to analyze their charge transports. The experimental data were fitted with straight lines at darkness and under illumination at 320 nm, 400 nm, and 515 nm. This indicates an ohmic behavior. Transport parameters were calculated. The conductive effect is stronger under darkness than under illumination at 320 nm because the oxidation process in the darkness is less intense than under illumination.

  5. 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.

  6. 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.

  7. 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.

  8. Selective defunctionalization by TiO2 of monomeric phenolics from lignin pyrolysis into simple phenols.

    PubMed

    Mante, Ofei D; Rodriguez, Jose A; Babu, Suresh P

    2013-11-01

    This study is focused on defunctionalizing monomeric phenolics from lignin into simple phenols for applications such as phenol/formaldehyde resins, epoxidized novolacs, adhesives and binders. Towards this goal, Titanium dioxide (TiO2) was used to selectively remove hydroxyl, methoxy, carbonyl and carboxyl functionalities from the monomeric phenolic compounds from lignin to produce mainly phenol, cresols and xylenols. The results showed that anatase TiO2 was more selective and active compared to rutile TiO2. Catechols were found to be the most reactive phenolics and 4-ethylguaiacol the least reactive with anatase TiO2. An overall conversion of about 87% of the phenolics was achieved at 550°C with a catalyst-to-feed ratio of 5 w/w. Over 97% conversion of phenolics is achievable at moderate temperatures (550°C or ≤ 600°C) and a moderate catalyst-to-feed ratio of 6.5:1. The reactivity of catechols on TiO2 suggests that titania is a promising catalyst in the removal of hydroxyl moiety. PMID:24080289

  9. Comparative study of TiO2 nanoparticles applied to dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Yacoubi, Besma; Bennaceur, Jamila; Ben Taieb, S.; Chtourou, Rathowan

    2014-02-01

    Microcrystalline titanium oxide (TiO2) particles of anatase crystal phase were prepared by the sol-gel route, varying thermal treatment conditions (400 °C and 600 °C), for a comparison purpose with commercial TiO2 (P25). Structural, optical and electrical properties were investigated for dye-sensitized solar cells (DSSCs) application. Both microcrystalline TiO2 particles, synthesized by the sol-gel method and obtained from the P25 powder were used to prepare a light scattering layer of the working electrode. The obtained electrodes were then immersed in a solution of N-719 (ruthenium) dye, at the ambient temperature, during 24 h. Finally, the DSSCs were assembled, the short circuit photocurrent, the open circuit photovoltage, and the power conversion efficiency were measured using an I-V measurement system. The overall conversion efficiencies for all elaborated DSSCs were proximate. A maximum efficiency of 2.3% was achieved for the sol-gel TiO2 thin film annealed at 400 °C, under one sun irradiation, with an open circuit voltage of 0.61 V and a current density of 6.54 mA/cm2. The higher efficiency value of the sol-gel TiO2 sample, annealed at 400 °C, was attributed to the uniformity of the prepared titanium oxide substrate, which provides a better surface for the dye absorption.

  10. Plasmonic photocatalysis properties of Au nanoparticles precipitated anatase/rutile mixed TiO2 nanotubes.

    PubMed

    Wen, Yan; Liu, Bitao; Zeng, Wei; Wang, Yuhua

    2013-10-21

    Anatase/rutile mixed titania nanotubes (TiO2 NTs) precipitated with gold nanoparticles (Au NPs), i.e. Au/TiO2, have been synthesized and investigated on visible photocatalysis properties. A deposition-precipitation (DP) method was adopted to reduce the gold precursor to Au NPs within the preformed TiO2 NTs by the emulsion electrospinning technique. The optimal visible photocatalytic activity was found in the sample Au3(DP350)/TiO2 with a loading of 3 wt% Au NPs and calcining at 350 °C. Through transmission electron microscopy, Au NPs of 4.16 nm diameter were observed at the interface between the anatase and rutile phases in the optimal Au3(DP350)/TiO2 sample, and these joint active sites at the interface were beneficial for charge separation. The obtained optimal photocatalytic efficiency of Au3(DP350)/TiO2 was ascribed to the synergistic effect of the enhanced visible absorption and the anatase/rutile mixed-phase composition, and the possible mechanism for this was discussed in detail. PMID:23963545

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Annealing effect on structural and optical properties of hydrothermally synthesized TiO2 nanowires.

    PubMed

    Hadia, N M A

    2014-07-01

    TiO2 nanowires (TiO2 NWs) were successfully synthesized in large amounts through the one step hydrothermal process in 10 M NaOH aqueous solution at 150 degrees C for 15 h followed by annealing at 300-800 degrees C for 2 h. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scan electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The optical properties of TiO2 nanowires were characterized using UV-VIS-NIR Spectrophotometers. It was found that the TiO2 nanowires persist in the anatase phase even after annealing at 500 degrees C and that the morphology of the nanowires was maintained. At 800 degrees C, the nanowires transformed into a rod-like shapes with a rutile structure. The optical band gap of TiO2 nanowires was found to decrease when the annealing temperature increases. PMID:24758068

  16. Calcination Conditions on the Properties of Porous TiO2 Film

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjie; Pei, Xiaobei; Bai, Jiawei; He, Hongbo

    2014-03-01

    Porous TiO2 films were deposited on SiO2 precoated glass-slides by sol-gel method using PEG1000 as template. The strongest XRD diffraction peak at 2θ = 25.3° is attributed to [101] plane of anatase TiO2 in the film. The increases of calcination temperature and time lead to stronger diffraction peak intensity. High transmittance and blue shift of light absorption edge are the properties of the film prepared at high calcination temperature. The average pore size of the films increases with the increasing calcination temperature as the result of TiO2 crystalline particles growing up and aggregation, accompanied with higher specific surface area. Photocatalytic activity of porous TiO2 films increases with the increasing calcination temperature. The light absorption edge of the films slightly moves to longer wavelength region along with the increasing calcination time. The mesoporous film calcinated at 500 °C for 2 h has the highest transmittance, the maximum surface area, and the maximum total pore volume. Consequently, the optimum degradation activity is achieved on the porous TiO2 film calcinated at 500 °C for 2 h.

  17. 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.

  18. 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

  19. TiO2 microboxes with controlled internal porosity for high-performance lithium storage

    DOE PAGESBeta

    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

  20. Photolithographically Patterned TiO2 Films for Electrolyte-Gated Transistors.

    PubMed

    Valitova, Irina; Kumar, Prajwal; Meng, Xiang; Soavi, Francesca; Santato, Clara; Cicoira, Fabio

    2016-06-15

    Metal oxides constitute a class of materials whose properties cover the entire range from insulators to semiconductors to metals. Most metal oxides are abundant and accessible at moderate cost. Metal oxides are widely investigated as channel materials in transistors, including electrolyte-gated transistors, where the charge carrier density can be modulated by orders of magnitude upon application of relatively low electrical bias (2 V). Electrolyte gating offers the opportunity to envisage new applications in flexible and printed electronics as well as to improve our current understanding of fundamental processes in electronic materials, e.g. insulator/metal transitions. In this work, we employ photolithographically patterned TiO2 films as channels for electrolyte-gated transistors. TiO2 stands out for its biocompatibility and wide use in sensing, electrochromics, photovoltaics and photocatalysis. We fabricated TiO2 electrolyte-gated transistors using an original unconventional parylene-based patterning technique. By using a combination of electrochemical and charge carrier transport measurements we demonstrated that patterning improves the performance of electrolyte-gated TiO2 transistors with respect to their unpatterned counterparts. Patterned electrolyte-gated (EG) TiO2 transistors show threshold voltages of about 0.9 V, ON/OFF ratios as high as 1 × 10(5), and electron mobility above 1 cm(2)/(V s). PMID:27193379

  1. The Partial Oxidation of Isobutene and Propene on TiO2(110)

    SciTech Connect

    Robbins, Matthew D.; Henderson, Michael A.

    2006-02-15

    General techniques for the partial oxidation of alkenes by molecular oxygen are a goal for surface science and catalysis research as they may lead to more efficient and environmentally friendly industrial processes. In order to better understand the thermal surface chemistry of metal oxides toward alkene partial oxidation, the interactions of isobutene and propene on TiO2(110) were studied using temperature programmed desorption (TPD). Isobutene was found to adsorb and desorb molecularly below 250 K on the clean surface. With exposure to oxygen (>1000 L) and unknown quantities of water (< 10 L), isobutene monolayers on TiO2(110) react to form products that include methacrolein and isobutanal, as well as a third product that possesses a C4H8O stoichiometry. We tentatively assign this species to 2,2-dimethyloxirane (isobutene oxide). Structural conservation within this family of products points to a common surface intermediate which we propose to result from addition of O from a hydrogen peroxo (HOO) species to the C=C bond of isobutene. This hydrogen peroxo (HOO) species forms from the reaction of physisorbed water and oxygen assisted by partial charge transfer from the TiO2(110) substrate. Initial studies reveal a similar reaction pathway for the partial oxidation of propene on TiO2(110), yielding acetone and propanal. This work suggests that TiO2 surface sites on supported Au/TiO2 catalysts are active for partial oxidation of alkenes.

  2. Interface feature characterization and Schottky interfacial layer confirmation of TiO2 nanotube array film

    NASA Astrophysics Data System (ADS)

    Li, Hongchao; Tang, Ningxin; Yang, Hongzhi; Leng, Xian; Zou, Jianpeng

    2015-11-01

    We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO2) nanotube array films fabricated by anodization. Field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the interface of the film. With increasing annealing temperature from 200 °C to 800 °C, the interfacial fusion between the film and the Ti substrate increased. The phase transformation of the TiO2 nanotube film from amorphous to anatase to rutile took place gradually; as the phase transformation progressed, the force needed to break the film increased. The growth of TiO2 nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO2 nanotubes grow from the Schottky interface layer rather than from the Ti substrate. The Schottky interface layer's thickness of 35-45 nm was identified as half the diameter of the corresponding nanotube, which shows good agreement to the Schottky interface layer growth model. The TiO2 nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

  3. 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

  4. Fe doped TiO2-graphene nanostructures: synthesis, DFT modeling and photocatalysis.

    PubMed

    Farhangi, Nasrin; Ayissi, Serge; Charpentier, Paul A

    2014-08-01

    In this work, Fe-doped TiO(2) 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 TiO(2) 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 TiO(2) analogs, showing a plateau at 0.6% Fe. Interactions between graphene and Fe-doped anatase TiO(2) 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 TiO(2). 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. PMID:25002220

  5. 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. PMID:25397324

  6. Fabrication of nano-structured TiO2 coatings using a microblast deposition technique

    NASA Astrophysics Data System (ADS)

    McDonnell, Kevin A.; English, Niall J.; Stallard, Charlie P.; Rahman, Mahfujur; Dowling, Denis P.

    2013-06-01

    Micron thick titanium dioxide (TiO2) coatings exhibiting a nano-structured, anatase, meso-porous structure were successfully deposited across a range of polymer, conductive glass and metallic substrates at low velocities using a microblasting technique. This process was conducted at atmospheric pressure using compressed air as the carrier gas and commercially available agglomerated nano particles of TiO2 as the feedstock. An examination of the effect of impact kinetics on the agglomerated powder before and after deposition was undertaken. A further examination of the coating microstructure along with photocurrent density measurements before and after thermal treatments was explored. Owing to the low temperature and velocity of the powder during deposition no change in phase of the powder or damage to the substrate was observed. The resulting TiO2 coatings exhibited relatively good adhesion on both titanium and FTO coated glass substrates with coating thickness of approximately 1.5 μm. Photo-catalytic performance was measured under solar simulator illumination using a photo-electrochemical cell (PEC) with a 5-fold increase in performance observed after thermal treatment of the TiO2 coated substrates. Microblasting was demonstrated to be a rapid and cost effective method for the deposition of nano-structured, photo-catalytic, anatase TiO2 coatings.

  7. Facile Synthesis of Robust Free-Standing TiO2 Nanotubular Membranes for Biofiltration Applications

    PubMed Central

    Schweicher, Julien; Desai, Tejal A.

    2014-01-01

    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

  8. 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

  9. Homogeneous Photosensitization of Complex TiO2 Nanostructures for Efficient Solar Energy Conversion

    PubMed Central

    Luo, Jingshan; Karuturi, Siva Krishna; Liu, Lijun; Su, Liap Tat; Tok, Alfred Iing Yoong; Fan, Hong Jin

    2012-01-01

    TiO2 nanostructures-based photoelectrochemical (PEC) cells are under worldwide attentions as the method to generate clean energy. For these devices, narrow-bandgap semiconductor photosensitizers such as CdS and CdSe are commonly used to couple with TiO2 in order to harvest the visible sunlight and to enhance the conversion efficiency. Conventional methods for depositing the photosensitizers on TiO2 such as dip coating, electrochemical deposition and chemical-vapor-deposition suffer from poor control in thickness and uniformity, and correspond to low photocurrent levels. Here we demonstrate a new method based on atomic layer deposition and ion exchange reaction (ALDIER) to achieve a highly controllable and homogeneous coating of sensitizer particles on arbitrary TiO2 substrates. PEC tests made to CdSe-sensitized TiO2 inverse opal photoanodes result in a drastically improved photocurrent level, up to ~15.7 mA/cm2 at zero bias (vs Ag/AgCl), more than double that by conventional techniques such as successive ionic layer adsorption and reaction. PMID:22693653

  10. 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

  11. Synthesis of hierarchical TiO2 nanowires with densely-packed and omnidirectional branches.

    PubMed

    Lee, Daeho; Rho, Yoonsoo; Allen, Frances I; Minor, Andrew M; Ko, Seung Hwan; Grigoropoulos, Costas P

    2013-11-21

    In this study, a hierarchical TiO2 nanostructure with densely-packed and omnidirectional branches grown by a hydrothermal method is introduced. This morphology is achieved via high-concentration TiCl4 treatment of upright backbone nanowires (NWs) followed by hydrothermal growth. Secondary nanobranches grow in all directions from densely distributed, needle-like seeds on the jagged round surface of the backbone NWs. In addition, hierarchical, flower-like branches grow on the top surface of each NW, greatly increasing the surface area. For dye-sensitized solar cell (DSSC) applications, the TiO2 nanostructure demonstrated a photoconversion efficiency of up to 6.2%. A parametric study of the DSSC efficiency showed that branched TiO2 DSSCs can achieve nearly four times the efficiency of non-branched TiO2 nanowire DSSCs, and up to 170% the efficiency of previously-reported sparsely-branched TiO2 NW DSSCs. PMID:24071926

  12. 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

  13. 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

  14. Preparation and characterization of TiO2 coated Fe nanofibers for electromagnetic wave absorber.

    PubMed

    Jang, Dae-Hwan; Song, Hanbok; Lee, Young-In; Lee, Kun-Jae; Kim, Ki Hyeon; Oh, Sung-Tag; Lee, Sang-Kwan; Choa, Yong-Ho

    2011-01-01

    Recently, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) have become serious problems due to the growth of electronic device and next generation telecommunication. It is necessary to develop new electromagnetic wave absorbing material to overcome the limitation of electromagnetic wave shielding materials. The EMI attenuation is normally related to magnetic loss and dielectric loss. Therefore, magnetic material coating dielectric materials are required in this reason. In this study, TiO2 coated Fe nanofibers were prepared to improve their properties for electromagnetic wave absorption. Poly(vinylpyrrolidone) (PVP) and Iron (III) nitrate nonahydrate (Fe(NO3)3 x 9H2O) were used as starting materials for the synthesis of Fe oxide nanofibers. Fe oxide nanofibers were prepared by electrospinning in an electric field and heat treatment. TiO2 layer was coated on the surface of Fe oxide nanofibers using sol-gel process. After the reduction of TiO2 coated Fe oxide nanofibers, Fe nanofibers with a TiO2 coating layer of about 10 nm were successfully obtained. The morphology and structure of fibers were characterized by SEM, TEM, and XRD. In addition, the absorption properties of TiO2 coated Fe nanofibers were measured by network analyzer. PMID:21446541

  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. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE PAGESBeta

    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

  17. Photoinduced hydroxyl radical and photocatalytic activity of samarium-doped TiO(2) nanocrystalline.

    PubMed

    Xiao, Qi; Si, Zhichun; Zhang, Jiang; Xiao, Chong; Tan, Xiaoke

    2008-01-15

    Sm(3+)-doped TiO(2) nanocrystalline has been prepared by sol-gel auto-combustion technique and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and also UV-vis diffuse reflectance spectroscopy (DRS). These Sm(3+)-doped TiO(2) samples were tested for methylene blue (MB) decomposition and *OH radical formation. The analysis of *OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with using terephthalic acid, which readily reacted with *OH radical to produce highly fluorescent product, 2-hydroxyterephthalic acid. It was observed that the presence of Sm(3+) ion as a dopant significantly enhanced the photocatalytic activity for MB degradation under UV light irradiation because both the larger specific surface area and the greater the formation rate of *OH radical were simultaneously obtained for Sm(3+)-doped TiO(2) nanocrystalline. The adsorption experimental demonstrated that Sm(3+)-TiO(2) had a higher MB adsorption capacity than undoped TiO(2) and the adsorption capacity of MB increased with the increase of samarium ion content. The results also indicated that the greater the formation rate of *OH radical was, the higher photocatalytic activity was achieved. In this study, the optimum amount of Sm(3+) doping was 0.5 mol%, at which the recombination of photo-induced electrons and holes could be effectively inhibited, the highest formation rate of *OH radicals was, and thereby the highest photocatalytic activity was achieved. PMID:17540502

  18. 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. PMID:18342358

  19. 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

  20. Decomposition of 3-chlorophenol on nitrogen modified TiO2 photocatalysts.

    PubMed

    Mozia, Sylwia; Bubacz, Kamila; Janus, Magdalena; Morawski, Antoni W

    2012-02-15

    Photocatalytic activity of nitrogen modified TiO(2) calcined at temperatures of 100-350°C toward 3-chlorophenol (3-CP) degradation was studied. In the experiments the fluorescent UV lamp and the incandescent lamp emitting mainly Vis light were applied. The degradation efficiency was evaluated on a basis of changes of 3-CP, total organic carbon and Cl(-) concentration. A significant improvement of the photoactivity of the N-modified photocatalysts compared to the reference sample was observed. The rate of 3-CP degradation increased with the calcination temperature, and the highest efficiency was achieved for TiO(2) annealed at 350°C. After 5h of UV irradiation in the presence of TiO(2)/N-350 and reference TiO(2) the 3-CP concentration decreased for 77% and 36%, respectively. The 3-CP removal after 24h of Vis irradiation was 30% and 12% for the N-modified and reference samples, respectively. The 3-CP decomposition and mineralization were greatly influenced by pH of the solution, achieving the highest rate at pH 7 for the modified photocatalysts. An increase of the calcination temperature resulted in an increase of the rate of OH formation. The photocatalytic activity of the N-modified TiO(2) remained unchanged during repeated photocatalytic degradation cycles. PMID:22192586

  1. 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.

  2. Dye adsorption and bactericidal properties of TiO2/chitosan coating layer.

    PubMed

    Kamal, Tahseen; Anwar, Yasir; Khan, Sher Bahadar; Chani, Muhammad Tariq Saeed; Asiri, Abdullah M

    2016-09-01

    A new kind of titanium oxide dispersed in chitosan (TiO2/CS) nanocomposite adsorbent was prepared and adhered to high surface area substrate, cellulose microfibers mat (CMM). CS-CMM and TiO2/CS-CMM were used for the thymol violet (TV) dye removal from wastewater. Characterization of materials was carried out by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The adsorption properties of both the CS-CMM and TiO2/CS-CMM were investigated as a function of adsorbent dosage, solution pH, and contact time. It was revealed that the composites pretreated in the solution with higher pH value exhibited larger adsorption capacities. Kinetic studies showed that the composites could adsorb TV dye rapidly and reached the equilibrium in 90min. The adsorption process followed pseudo-second order kinetics and involved particle diffusion mechanism. The calculated maximum adsorption capacities of CS-CMM and TiO2/CS-CMM were 84.32 and 97.51mgg(-1), respectively. Compare to CS, the TiO2/CS nanocomposite coated CMM showed higher antibacterial characteristics as tested against Escherichia coli. PMID:27185126

  3. 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.

  4. 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.

  5. Excited-state dynamics of size-dependent colloidal TiO2-Au nanocomposites.

    PubMed

    Karam, Tony E; Khoury, Rami A; Haber, Louis H

    2016-03-28

    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. PMID:27036472

  6. 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.

  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. 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.

  9. Highly enhanced luminescence of nanocrystalline TiO 2:Eu 3+ phosphors

    NASA Astrophysics Data System (ADS)

    Yi, Soung-soo; Bae, Jong Seong; Moon, Byung Kee; Jeong, Jung Hyun; Kim, Jung Hwan

    2006-05-01

    Narrow-dispersed nanocrystalline TiO 2:Eu 3+ phosphors have been synthesized by reverse micelles and solvothermal synthetic method in toluene solutions. Different concentrations of europium nitrate pentahydrate (5.0, 10.0, 20.0 and 25.0 mol%) were dissolved in water. After the solution was thermally treated at 250 °C for 20 h in an autoclave, low-dispersed TiO 2:Eu 3+ nanocrystalline particles with average size of <5 nm were synthesized. The nanocomposites were composed nominally of TiO 2 shell with Eu 2O 3 core. The crystalline phase and microstructure of the nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Also, luminescent spectra and composition ratio were measured using luminescent spectrometer and energy dispersive X-ray spectrometer. The radiation was dominated by the red emission peak at 616 nm and the highest emission intensity was observed with TiO 2:Eu 0.2, whose brightness was increased by a factor of 1.9 in comparison with that of TiO 2:Eu 0.05. The photoluminescence and excitation spectra show similar behavior as a function of Eu concentration.

  10. 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.

  11. Preparation of atomically flat TiO2(001) surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Weitering, Hanno H.; Snijders, Paul C.

    2015-03-01

    Transition metal oxides with the rutile structure (MO2, M = e.g. Ti, V, or Nb) have highly directional partially occupied t2g orbitals. Some of these orbitals form quasi-1D electronic bands along the rutile c-axis, and Peierls-like ordering phenomena have been observed in VO2 and NbO2. Tailoring the electronic properties of these materials via quantum confinement requires epitaxial growth on suitable substrates such as low index TiO2 surfaces. Because of the high surface energy of rutile TiO2(001), the standard approach of sputtering and annealing usually introduces faceting. Here we demonstrate a facile method to create atomically flat, non-faceted TiO2(001) surfaces. Using scanning tunneling microscopy we observe terraces with a width of approximately 150 nm. Step heights of approximately 0.3 nm are observed, consistent with the c lattice parameter of rutile TiO2. Low energy electron diffraction patterns reveal sharp diffraction spots with an in-plane lattice constant of 0.358 nm which is consistent with a (1x1) ordering of the (001) plane. These TiO2(001) single crystal surfaces can serve as an ideal substrate for further growth of rutile heterostructures. Research sponsored by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  12. The properties of TiO2 nanoceramic films prepared by electron beam evaporation.

    PubMed

    Lin, Su-Shia; Hung, Yuan-Hsun; Chen, Shin-Chi

    2009-06-01

    TiO2 nanoceramic films were deposited on polycarbonate (PC) substrate by electron beam evaporation. This deposition technique is well established for producing dense and adhesive optical films. At high power, the particles arrived at the substrate with high kinetic energy, and high impact also led to low density due to porous structure. The porous TiO2 films resulted in low linear refractive index. As the film thickness increased, the surface of TiO2 films exhibited the grain growth obviously, resulting in high surface roughness. The transparent TiO2 films showed red-shift because of large grain size. Transparent materials generally have optical Kerr effect. The knowledge of nonlinear refractive index of materials is of great interest due to its potential applications in designing optical devices. Moiré deflectometry is a powerful tool for measuring nonlinear refractive index of materials. In this study, this method is applied for measuring the nonlinear refractive index of TiO2 nanoceramic films on PC substrates. The nonlinear refraction index can be measured to be in order of 10(-8) cm2 W(-1) and the change in refractive index is in order of 10(-5). PMID:19504888

  13. Self-induced preparation of TiO2 nanowires by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Du, Jun; Gu, Xin; Guo, Haizhi; Liu, Jiao; Wu, Qi; Zou, Jianguo

    2015-10-01

    High-density single-crystalline TiO2 nanowires are successfully fabricated on a TiSi2 layer using a new self-induced catalyst-free method by APCVD. The results show that the high aspect ratio nanowires with diameters of 20-50 nm and lengths of about 3 μm are obtained on a TiSi2 layer at 720 °C. The length of TiO2 nanowires increases with the preparation time until Ti is exhausted. The nanowires shape changes with the concentration of O2 and temperature. When the temperature is above 720 °C or the flux of O2 is over 6 sccm, the density and length of nanowires decrease under the combined effect of the increasing lateral surface diffusion and longitudinal growth. The formation of TiO2 nanowires comes along with the consumption of TiSi2, TiO2 nanowires grow along the [001] direction of the tetragonal rutile TiO2 crystal from the bottom, with the tip being pushed upwards. The growth process is proposed which is consistent with our experiment results.

  14. 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.

  15. Samarium-doped mesoporous TiO2 nanoparticles with improved photocatalytic performance for elimination of gaseous organic pollutants

    NASA Astrophysics Data System (ADS)

    Tang, Jianting; Chen, Xiaomiao; Liu, Yu; Gong, Wei; Peng, Zhenshan; Cai, Tiejun; Luo, Lianjing; Deng, Qian

    2013-01-01

    Mesoporous TiO2 doped with different amounts of Sm were prepared via a sol-gel route with Pluronic P123 as template. The materials were characterized by X-ray diffraction, transmission electron microscopy, and N2 sorption experiments, etc. The photocatalytic activity of the mesoporous TiO2 was tested in elimination of gaseous methanol and acetone. The Sm doped mesoporous TiO2 have higher activity than those of the commercial photocatalyst (Degussa, P25) and Sm doped TiO2 counterparts without mesopore structure under ultraviolet light irradiation. A possible mechanism was proposed to account for the high photocatalytic activity of the Sm doped mesoporous TiO2. The superior activity of the Sm doped mesoporous TiO2 may be attributed to the synergic effect of the high surface area, mesopore structure and doped Sm species.

  16. 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

  17. Influence of VB group doped TiO2 on photovoltaic performance of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Duan, Yandong; Zhou, Xiaowen; Lin, Yuan

    2013-07-01

    Dye-sensitized solar cell with VB group (vanadium (V), niobium (Nb) and tantalum (Ta)) doped TiO2 prepared by hydrothermal method shows a higher photovoltaic efficiency compared with the undoped TiO2. All the VB doping shift the flat band potential positively and increase the doping density which is investigated by Mott-Schottky plot. The positive shift of flat band potential improves the driving force of injecting electron from the LUMO of dye to the conduction band of TiO2 and the photocurrent. On the other hand, the increase of doping density accelerates transfer rate of electrons in TiO2 than the un-doped, which is confirmed by intensity-modulated photocurrent. V-, Nb-, Ta-doped TiO2 exhibited photovoltaic performance with 7.80%, 8.33%, 8.18%, respectively, compared with that of the cells based on pure TiO2 (7.42%).

  18. A facile and versatile method for preparation of colored TiO2 with enhanced solar-driven photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Tan, Huaqiao; Zhao, Zhao; Niu, Mang; Mao, Chengyu; Cao, Dapeng; Cheng, Daojian; Feng, Pingyun; Sun, Zaicheng

    2014-08-01

    Colored TiO2 has attracted enormous attention due to its visible light absorption and excellent photocatalytic activity. In this report, we develop a simple and facile solid-state chemical reduction approach for a large-scale production of colored TiO2 at mild temperature (300-350 °C). The obtained sample possesses a crystalline core/amorphous shell structure (TiO2@TiO2-x). The oxygen vacancy results in the formation of a disordered TiO2-x shell on the surface of TiO2 nanocrystals. XPS and theoretical calculation results indicate that valence band tail and vacancy band below the conduction band minimum appear for the TiO2-x, which implies that the TiO2@TiO2-x nanocrystal has a narrow band gap and therefore leads to a broad visible light absorption. Oxygen vacancy in a proper concentration promotes the charge separation of photogenerated carriers, which improves the photocatalytic activity of TiO2@TiO2-x nanocrystals. This facile and general method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven H2 production.Colored TiO2 has attracted enormous attention due to its visible light absorption and excellent photocatalytic activity. In this report, we develop a simple and facile solid-state chemical reduction approach for a large-scale production of colored TiO2 at mild temperature (300-350 °C). The obtained sample possesses a crystalline core/amorphous shell structure (TiO2@TiO2-x). The oxygen vacancy results in the formation of a disordered TiO2-x shell on the surface of TiO2 nanocrystals. XPS and theoretical calculation results indicate that valence band tail and vacancy band below the conduction band minimum appear for the TiO2-x, which implies that the TiO2@TiO2-x nanocrystal has a narrow band gap and therefore leads to a broad visible light absorption. Oxygen vacancy in a proper concentration promotes the charge separation of photogenerated carriers, which improves the photocatalytic activity of TiO2@TiO2-x nanocrystals. This facile and general method could be potentially used for large scale production of colored TiO2 with remarkable enhancement in the visible light absorption and solar-driven H2 production. Electronic supplementary information (ESI) available: More XRD, UV-Vis spectra, XPS, SEM, TEM and photocatalytic degradation of MO. See DOI: 10.1039/c4nr02677b

  19. 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). PMID:25924333

  20. Defective TiO2-supported Cu nanoparticles as efficient and stable electrocatalysts for oxygen reduction in alkaline media

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Song, Yang; Chen, Shaowei

    2014-12-01

    Nanocomposites based on TiO2-supported copper nanoparticles were prepared by a hydrothermal method where copper nanoparticles with or without the passivation of 1-decyne were chemically grown onto TiO2 nanocolloid surfaces (and hence denoted as CuHC10/TiO2 and Cu/TiO2, respectively). Transmission electron microscopy measurements showed that the size of the hybrid nanoparticles was 5-15 nm in diameter with clearly defined lattice fringes for anatase TiO2(101) and Cu(111). The formation of anatase TiO2 nanoparticles was also observed by X-ray diffraction measurements. FTIR measurements confirmed successful attachment of alkyne ligands onto the surface of the copper nanoparticles via Cu-C&z.tbd; interfacial bonds in CuHC10/TiO2. XPS measurements suggested the formation of CuO in both samples with a higher concentration in Cu/TiO2, and interestingly Ti3+ species were found in CuHC10/TiO2 but were absent in Cu/TiO2 or TiO2 nanoparticles. Electrochemical studies demonstrated that both Cu/TiO2 and CuHC10/TiO2 exhibited a markedly improved electrocatalytic performance in the oxygen reduction reaction, as compared to TiO2 nanocolloids alone, in the context of the onset potential, the number of electrons transferred and the kinetic current density. Importantly, among the series, CuHC10/TiO2 exhibited the best ORR activity with a high current density, an almost four-electron reduction pathway and long-term stability after 4000 cycles at high potentials, which may be ascribed to the defective TiO2 structures in combination with surface ligand engineering.Nanocomposites based on TiO2-supported copper nanoparticles were prepared by a hydrothermal method where copper nanoparticles with or without the passivation of 1-decyne were chemically grown onto TiO2 nanocolloid surfaces (and hence denoted as CuHC10/TiO2 and Cu/TiO2, respectively). Transmission electron microscopy measurements showed that the size of the hybrid nanoparticles was 5-15 nm in diameter with clearly defined lattice fringes for anatase TiO2(101) and Cu(111). The formation of anatase TiO2 nanoparticles was also observed by X-ray diffraction measurements. FTIR measurements confirmed successful attachment of alkyne ligands onto the surface of the copper nanoparticles via Cu-C&z.tbd; interfacial bonds in CuHC10/TiO2. XPS measurements suggested the formation of CuO in both samples with a higher concentration in Cu/TiO2, and interestingly Ti3+ species were found in CuHC10/TiO2 but were absent in Cu/TiO2 or TiO2 nanoparticles. Electrochemical studies demonstrated that both Cu/TiO2 and CuHC10/TiO2 exhibited a markedly improved electrocatalytic performance in the oxygen reduction reaction, as compared to TiO2 nanocolloids alone, in the context of the onset potential, the number of electrons transferred and the kinetic current density. Importantly, among the series, CuHC10/TiO2 exhibited the best ORR activity with a high current density, an almost four-electron reduction pathway and long-term stability after 4000 cycles at high potentials, which may be ascribed to the defective TiO2 structures in combination with surface ligand engineering. Electronic supplementary information (ESI) available: FTIR spectra and Koutecky-Levich plots. See DOI: 10.1039/c4nr06128d

  1. Comparison of electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb, Ge, Zr-added TiO2 composite electrodes.

    PubMed

    Imahori, Hiroshi; Hayashi, Shinya; Umeyama, Tomokazu; Eu, Seunghun; Oguro, Akane; Kang, Soonchul; Matano, Yoshihiro; Shishido, Tetsuya; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h. PMID:17154633

  2. 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

  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. PMID:21762957

  4. Band gap engineered, oxygen-rich TiO2 for visible light induced photocatalytic reduction of CO2.

    PubMed

    Tan, Lling-Lling; Ong, Wee-Jun; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2014-07-01

    A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light. PMID:24841282

  5. Photoelectrochemical characterization of a robust TiO2/BDD heterojunction electrode for sensing application in aqueous solutions.

    PubMed

    Han, Yanhe; Zhang, Shanqing; Zhao, Huijun; Wen, William; Zhang, Haimin; Wang, Hongjuan; Peng, Feng

    2010-04-20

    Titanium dioxide (TiO(2)) and boron-doped diamond (BDD) are two of the most popular functional materials in recent years. In this work, TiO(2) nanoparticles were immobilized onto the BDD electrodes by a dip-coating technique. Continuous and uniform mixed-phase (anatase and rutile) and pure-anatase TiO(2)/BDD electrodes were obtained after calcination processes at 700 and 450 degrees C, respectively. The particle sizes of both types of TiO(2) film range from 20 to 30 nm. In comparison with a TiO(2)/indium tin oxide (ITO) electrode, the TiO(2)/BDD electrode demonstrates a higher photoelectrocatalytic activity toward the oxidation of organic compounds, such as glucose and potassium hydrogen phthalate. Among all the tested TiO(2) electrodes, the mixed-phase TiO(2)/BDD electrode demonstrated the highest photoelectrocatalytic activity, which can be attributed to the formation of the p-n heterojunction between TiO(2) and BDD. The electrode was subsequently used to detect a wide spectrum of organic compounds in aqueous solution using a steady-state current method. An excellent linear relationship between the steady-state photocurrents and equivalent organic concentrations was attained. The steady-state oxidation photocurrents of the mixed-phase TiO(2)/BDD electrode were insensitive to pH in the range of pH 2-10. Furthermore, the electrodes exhibited excellent robustness under strong acidic conditions that the TiO(2)/ITO electrodes cannot stand. These characteristics bestow the mixed-phase TiO(2)/BDD electrode to be a versatile material for the sensing of organic compounds. PMID:20030335

  6. 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

  7. Optimizing TiO2-based phosphopeptide enrichment for automated multidimensional liquid chromatography coupled to tandem mass spectrometry

    PubMed Central

    Cantin, Greg T.; Shock, Teresa R.; Park, Sung Kyu; Madhani, Hiten D.; Yates, John R.

    2008-01-01

    An automated online multidimensional liquid chromatography system coupled to ESI-based tandem mass spectrometry was used to assess the effectiveness of TiO2 in the enrichment of phosphopeptides from tryptic digests of protein mixtures. By monitoring the enrichment of phosphopeptides, an optimized set of loading, wash, and elution conditions were realized for TiO2. A comparison of TiO2 with other resins used for phosphopeptide enrichment, Fe(III)-IMAC and ZrO2, was also carried out using tryptic digests of both simple and moderately complex protein mixtures; where TiO2 was shown to be superior in performance. PMID:17523591

  8. Properties of dye-sensitized solar cells with TiO2 passivating layers prepared by electron-beam evaporation.

    PubMed

    Jin, Young Sam; Choi, Hyung Wook

    2012-01-01

    The aim of this work is to prevent back transfer of electrons due to direct contact between the electrolyte and the FTO glass substrate using a TiO2 passivating layer. The TiO2 passivating layer was deposited on FTO glass by e-beam evaporation. The TiO2 film was prepared with different deposition rates. The specific surface area was reduced with increasing deposition rate. The nanoporous TiO2 upper layer was coated by screen-printing on the TiO2 passivating layer prepared by e-beam evaporation. The optical transmittance and absorbance of the TiO2 films depend on the morphology of the TiO2 passivating layer. The dye-sensitized solar cells influenced the surface morphology of the TiO2 passivating layer. The dye-sensitized solar cell using the TiO2 passivating layer recorded a maximum conversion efficiency of 4.93% due to effective prevention of the electron recombination to the electrolyte. PMID:22524036

  9. Novel TiO2/C nanocomposites: synthesis, characterization, and application as a photocatalyst for the degradation of organic pollutants.

    PubMed

    da Costa, Elias; Zamora, Patricio P; Zarbin, Aldo J G

    2012-02-15

    Novel TiO(2)/carbon nanocomposites were prepared through the pyrolysis of TiO(2)/poly(furfuryl alcohol) hybrid materials, which were obtained by the sol-gel method, starting from titanium tetraisopropoxide (TTIP) and furfuryl alcohol (FA) precursors. Six different TiO(2)/C samples were prepared based on different TiO(2) nanoparticle sizes and TiO(2)/FA ratios. All of the samples were characterized using X-ray diffraction, infrared, and Raman spectroscopy. The results indicated effective FA polymerization onto the TiO(2) (anatase) nanoparticles, polymer conversion to disordered carbon following the pyrolysis, and a simultaneous TiO(2) anatase-rutile phase transition. The resulting TiO(2)/carbon composites were used as photocatalysts in the advanced oxidative process (AOP) for the degradation of reactive organic dyes in aqueous solution. The results indicate excellent photocatalytic performance (degradation of 99% of the dye after 60 min) with several advantages over traditional TiO(2)-based photocatalysts. PMID:22056275

  10. Nanostructured TiO2 films for dye-sensitized solar cells prepared by the sol-gel method.

    PubMed

    Jin, Young Sam; Kim, Kyung Hwan; Park, Sang Joon; Yoon, Hyon Hee; Choi, Hyung Wook

    2011-12-01

    TiO2 films were prepared on glass substrates using the sol-gel process for a dye-sensitized solar cell application. The TiO2 sol was prepared using hydrolysis/polycondensation. Titanium (IV) Tetra Isopropoxide (TTIP) was used as precursor and Nitric acid (HNO3) was used as a catalyst for the peptization. The crystal structure and morphology of the prepared materials were characterized by XRD, and an SEM. The observations confirmed the nanocrystalline nature of the TiO2. The reaction parameters, such as the catalyst concentrations, the calcination time, and the calcination temperature were varied during the synthesis in order to achieve nanosize TiO2 particles. The prepared TiO2 particles were coated onto FTO glass using a screen printing technique. The prepared TiO2 films were characterized by UV-vis. The TiO2 particles calcinated at low temperatures showed an anatase phase they grew into a rutile phase when the calcination temperature increased. The size and structure of the TiO2 particles were adjusted to specific surface areas. It was found that the conversion efficiency of the DSSC was highly affected by the properties of the TiO2 particles. PMID:22409037

  11. Enhanced methanol oxidation activity and stability of Pt particles anchored on carbon-doped TiO2 nanocoating support

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Li, Yunfeng; Lv, Ren-Liang; Wang, Tie-Lin; Wang, Wei-Guo; Wang, Cun-Wen

    2015-03-01

    In this work, carbon-doped TiO2 nanocoating (TiO2-C) was prepared by a sol-gel process and employed as the support of Pt nanoparticles for methanol oxidation reaction (MOR). The obtained Pt/TiO2-C catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. XRD characterization shows that the average crystallite sizes of Pt particles and TiO2-C support are 2.7 and 6.5 nm, respectively. TEM characterizations show that Pt particles are highly dispersed on TiO2 nanocoating, which preserves its nanoscale structure without no apparent sintering after carbon doping. XPS characterization shows that the Pt particles anchored on TiO2-C exhibit positively shifted binding energies of Pt 4f. Cyclic voltammetry (CV) and chronoamperometry (CA) characterizations show that TiO2-C has a greatly enhanced electrical conductivity and Pt/TiO2-C catalyst has better electrocatalytic activity and stability than Pt/C catalyst for MOR, which could be attributed to the high dispersion of Pt particles on TiO2-C support, the strong metal-support interactions between Pt particles and TiO2-C support, and the rich active -OH species on TiO2-C support.

  12. Modification of physicochemical and thermal properties of starch films by incorporation of TiO2 nanoparticles.

    PubMed

    Oleyaei, Seyed Amir; Zahedi, Younes; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

    2016-08-01

    In this research, potato starch and TiO2 nanoparticles (0.5, 1 and 2wt%) films were developed. Influences of different concentrations of TiO2 on the functional properties of nanocomposite films (water-related properties, mechanical characteristics, and UV transmittance) were investigated. XRD, FTIR, and DSC analyses were used to characterize the morphology and thermal properties of the films. The results revealed that TiO2 nanoparticles dramatically decreased the values of water-related properties (water vapor permeability: 11-34%; water solubility: 1.88-9.26%; moisture uptake: 2.15-11.18%). Incorporation of TiO2 led to a slight increment of contact angle and tensile strength, and a decrease in elongation at break of the films. TiO2 successfully blocked more than 90% of UV light, while opacity and white index of the films were enhanced. Glass transition temperature and melting point of the films were positively affected by the addition of TiO2 nanoparticles. The result of XRD study exhibited that due to a limited agglomeration of TiO2 nanoparticles, the mean crystal size of TiO2 increased. Formation of new hydrogen bonds between the hydroxyl groups of starch and nanoparticles was confirmed by FTIR spectroscopy. In conclusion, TiO2 nanoparticles improved the functional properties of potato starch film and extended the potential for food packaging applications. PMID:27132884

  13. 3D silk fibroin scaffold incorporating titanium dioxide (TiO2) nanoparticle (NPs) for tissue engineering.

    PubMed

    Kim, Jung-Ho; Sheikh, Faheem A; Ju, Hyung Woo; Park, Hyun Jung; Moon, Bo Mi; Lee, Ok Joo; Park, Chan Hum

    2014-07-01

    The present study deals with fabrication of scaffolds composing of silk fibroin and TiO2 NPs fabricated using a salt-leaching process. At first instance, the TiO2 NPs were prepared by using sol-gel synthesis, affording to have average diameter of 77±21μm. Furthermore, the aqueous solutions of silk fibroin were mixed with 0.2%, 2.0% and 4.0% of TiO2 NPs and salt-leaching process was introduced which resulted in creation of porous scaffolds modified with TiO2 NPs. The presence of TiO2 NPs in scaffolds was confirmed by VP-FE-SEM-EDS, TGA and XRD. The presence of TiO2 NPs influenced in decrease in pore size and swelling behavior of composite scaffolds. The resultant mechanical property of scaffolds was improved upon the introduction of TiO2 NPs. Moreover, cell cytotoxicity results for 1, 3 and 7 days; revealed no toxic behavior to osteoblasts. However, a mild toxicity to NIH 3T3 fibroblasts was observed with the scaffolds containing 4.0% TiO2 NPs. The cell fixation results from 1 and 7 days of incubation indicated the attachment, spreading and subsequent proliferation of fibroblasts. However, these findings were independent to the amount of TiO2 NPs in scaffolds. PMID:24794196

  14. Nano porous Al2O3-TiO2 thin film based humidity sensor prepared by spray pyrolysis technique

    NASA Astrophysics Data System (ADS)

    Chandrashekara, H. D.; Angadi, Basavaraj; Ravikiran, Y. T.; Poornima, P.; Shashidhar, R.; Murthy, L. C. S.

    2016-05-01

    The nano porous surface structured TiO2 and Al2O3-TiO2 thin films were prepared using spray pyrolysis technique at 350°C. The XRD pattern of Al2O3-TiO2 film shows anatase phase and mixed phase of Al2TiO5. The surface morphology of films show a uniformly distributed nano porous structure. The elemental analysis through EDAX shows good stoichiometry. The sensitivity for humidity sensing were determined for both films of TiO2 and Al2O3-TiO2 and corresponding values are found to be 74.2% and 84.02%, this result reveal that Al2O3-TiO2 films shows higher sensing percent than the TiO2 due to the nano porous surface nature. The Al2O3-TiO2 film shows fast response time and long recovery time than the TiO2 film, this may be due to the meso-porous morphology of these films.

  15. Effect of sulfur doped TiO2 on photovoltaic properties of dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Seo, Hyunwoong; Nam, Sang-Hun; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Boo, Jin-Hyo

    2016-07-01

    In a dye-sensitized solar cell (DSC), a nano-porous semiconductor layer plays an important role in the performance. It determines open-circuit voltage and it affects the dye adsorption capacity and charge transfer, which are closely associated with photocurrent and overall performance. TiO2 is the most proper material for nano-porous layer since the first development of DSCs. This work focuses on the enhancement of TiO2 by doping. Sulfur (S) doping enhances charge transfer and the photoconversion of TiO2. Therefore, the increase in photocurrent and efficiency is expected by S doping. S is doped into TiO2 by hydrolysis method. The amount of S is varied and their photo-responses are verified. The most effective S doped TiO2 is applied to DSCs. Overall performance of DSC is enhanced by the addition of S doped TiO2. Especially, the photocurrent is much increased by the improvement on charge transfer, electron lifetime, and photo-conversion. The photovoltaic properties of DSCs are investigated with various ratios of undoped and S doped TiO2. Finally, a DSC based on undoped and S doped TiO2 ratio of 1:1 has the highest efficiency, better than that of a standard DSC based on undoped TiO2. [Figure not available: see fulltext.

  16. Preparation of nanostructured TiO2-based photocatalyst by controlling the calcining temperature and pH

    NASA Astrophysics Data System (ADS)

    Uddin, Mohammed Jasim; Islam, Md Akhtarul; Haque, Sheikh Ariful; Hasan, Saidul; Amin, Mohammad Shaiful Alam; Rahman, Mohammed Mastabur

    2012-08-01

    Nanostructured TiO2 has been synthesized using one-step sol-gel method and characterized by different characterization techniques (SEM, EDS, XRD, and UV-vis spectroscopy). The photocatalytic degradation of methylene blue (MB) and Congo red (CR) is studied with the synthesized TiO2. The photocatalytic degradation data has been validated using several kinetic models. The TiO2 showed efficient photocatalytic degradation performance on MB and CR. In addition to this, the effect of pH on the photocatalytic degradation has been investigated. The TiO2 showed enhanced photocatalytic performance in basic media than that in neutral or acidic ones.

  17. Hydrogen plasma reduced black TiO2sbnd B nanowires for enhanced photoelectrochemical water-splitting

    NASA Astrophysics Data System (ADS)

    Tian, Zhangliu; Cui, Huolei; Zhu, Guilian; Zhao, Wenli; Xu, JiJian; Shao, Feng; He, Jianqiao; Huang, Fuqiang

    2016-09-01

    Black TiO2 with various nanostructures and phase constitutions have been reported to exhibit excellent photocatalytic and photoelectrochemical (PEC) performance. Here, we report the fabrication of black nanostructured TiO2sbnd B through hydrogen plasma assisted reduction and its enhanced PEC properties for the first time. Both the obtained TiO2sbnd B and black TiO2sbnd B are single crystalline nanowires, while the black TiO2sbnd B samples exhibit much stronger visible and infrared light absorption. The optimal black TiO2sbnd B sample obtained by hydrogen plasma treatment at 425 °C yields a photocurrent density of 0.85 mA cm-2, a rather low onset potential of -0.937 VAg/AgCl and a high applied bias photon-to-current efficiency (ABPE) of 0.363%, which is far superior to the TiO2sbnd B (0.15 mA cm-2 photocurrent, -0.917 VAg/AgCl onset potential and 0.138% ABPE). The significantly enhanced PEC performance of the black TiO2sbnd B is ascribed to the introduction of moderate surface oxygen vacancies. These results indicate that the black TiO2sbnd B is a promising material for PEC application and solar energy utilization.

  18. 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. PMID:26353679

  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. Fabrication of UV Photodetector on TiO2/Diamond Film

    NASA Astrophysics Data System (ADS)

    Liu, Zhangcheng; Li, Fengnan; Li, Shuoye; Hu, Chao; Wang, Wei; Wang, Fei; Lin, Fang; Wang, Hongxing

    2015-09-01

    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.