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Sample records for ag doped tio2

  1. 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.

  2. The Synthesis of Ag-Doped Mesoporous TiO2

    SciTech Connect

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

    2008-04-15

    Ag-doped mesoporous titanium oxide was prepared using non-ionic surfactants and easily handled titanium precursors, under mild reaction conditions. In contrast to the stabilizing effect of Cd-doping on mesoporous TiO2, Ag-doping was found to significantly destabilize the mesoporous structure.

  3. Photocatalytic comparison of Cu- and Ag-doped TiO2/GF for bioaerosol disinfection under visible light

    NASA Astrophysics Data System (ADS)

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2015-12-01

    Photocatalysts, TiO2/glass fiber (TiO2/GF), Cu-doped TiO2/glass fiber (Cu-TiO2/GF) and Ag-doped TiO2/glass fiber (Ag-TiO2/GF), were synthesized by a sol-gel method. They were then used to disinfect Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in bioaerosols under visible light irradiation. TiO2/GF did not show any significant disinfection effect. Both Cu and Ag acted as intermediate agents to enhance separation efficiency of electron-hole pairs of TiO2, leading to improved photocatalytic activity of Cu-TiO2/GF and Ag-TiO2/GF under visible light. Cu in Cu-TiO2/GF acted as a defective agent, increasing the internal quantum efficiency of TiO2, while Ag in Ag-TiO2/GF acted as a sensitive agent, enhancing the transfer efficiency of the electrons generated. The highest disinfection efficiencies of E. coli and S. aureus by Cu-TiO2/GF were 84.85% and 65.21%, respectively. The highest disinfection efficiencies of E. coli and S. aureus by Ag-TiO2/GF were 94.46% and 73.12%, respectively. Among three humidity conditions - 40±5% (dry), 60±5% (moderate), and 80±5% (humid) - the moderate humidity condition showed the highest disinfection efficiency for both E. coli and S. aureus. This study also showed that a Gram-negative bacterium (E. coli) were more readily disinfected by the photocatalysts than a Gram-positive bacterium (S. aureus).

  4. Antibacterial Activity of As-Annealed TiO2 Nanotubes Doped with Ag Nanoparticles against Periodontal Pathogens

    PubMed Central

    Yeniyol, Sinem; He, Zhiming; Yüksel, Behiye; Boylan, Robert Joseph; Ürgen, Mustafa; Özdemir, Tayfun; Ricci, John Lawrence

    2014-01-01

    It is important to develop functional transmucosal implant surfaces that reduce the number of initially adhering bacteria and they need to be modified to improve the anti-bacterial performance. Commercially pure Ti sheets were anodized in an electrolyte containing ethylene glycol, distilled water and ammonium fluoride at room temperature to produce TiO2 nanotubes. These structures were then annealed at 450°C to transform them to anatase. As-annealed TiO2 nanotubes were then treated in an electrolyte containing 80.7 g/L NiSO4·7H2O, 41 g/L MgSO4·7H2O, 45 g/L H3BO3, and 1.44 g/L Ag2SO4 at 20°C by the application of 9 V AC voltage for doping them with silver. As-annealed TiO2 nanotubes and as-annealed Ag doped TiO2 nanotubes were evaluated by SEM, FESEM, and XRD. Antibacterial activity was assessed by determining the adherence of A. actinomycetemcomitans, T. forsythia, and C. rectus to the surface of the nanotubes. Bacterial morphology was examined using an SEM. As-annealed Ag doped TiO2 nanotubes revealed intense peak of Ag. Bacterial death against the as-annealed Ag doped TiO2 nanotubes were detected against A. actinomycetemcomitans, T. forsythia, and C. rectus indicating antibacterial efficacy. PMID:25202230

  5. 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.

  6. Photocatalytic characteristics for the nanocrystalline TiO2 on the Ag-doped CaAl2O4:(Eu,Nd) phosphor

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Sik; Sung, Hyun-Je; Kim, Bum-Joon

    2015-04-01

    This study investigated the photocatalytic behavior of nanocrystalline TiO2 deposited on Ag-doped long-lasting phosphor (CaAl2O4:Eu2+,Nd3+). The CaAl2O4:Eu2+,Nd3+ phosphor powders were prepared via conventional sintering using CaCO3, Al2O3, Eu2O3, and Nd2O3 as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO2 was deposited on Ag-doped CaAl2O4:Eu2+,Nd3+ powders via low-pressure chemical vapor deposition (LPCVD). The TiO2 coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO2, which is almost non-reactive. The coupling of TiO2 with phosphor may result in an energy band bending in the junction region, which then induces the TiO2 crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO3 that formed at the interface between TiO2 and the CaAl2O4:(Eu2+,Nd3+) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO2/CaAl2O4:Eu2+,Nd3+ phosphor. TiO2 on the Ag-doped phosphor presented a higher benzene gas decomposition rate than the TiO2 did on the phosphor without Ag-doping under both irradiation with ultraviolet and visible light.

  7. Synthesis of Ag-doped TiO2 nanoparticles by combining laser decomposition of titanium isopropoxide and ablation of Ag for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Al-Kamal, Ahmed Kamal

    Nanostructured powders of TiO2 and Ag-doped TiO2 are synthesized by a novel pulsed-laser process that combines laser ablation of a silver (Ag) disc with laser decomposition of a titanium tetra-isopropoxide (TTIP) solution. Nanoparticles are formed by rapid condensation of vaporized species in the plasma plume generated by the high power laser, resulting in the formation of rapidly quenched Ag-doped TiO2 nanoparticles that have far-from-equilibrium or metastable structures. The uniqueness of the new ablation process is that it is a one-step process, in contrast to the two-step process developed by previous researchers in the field. Moreover, its ability to synthesize an extended-solid solution phase of Ag in TiO 2 may also be unique. The present work implies that other oxide phases, such as Al2O3, MgO and MgAl2O4, can be doped with normally insoluble metals, such as Pt and Ir, thus opening new opportunities for catalytic applications. Again, there is the prospect of being able to synthesize nanopowders of diamond, c-BN, and mixtures thereof, which are of interest for applications in machine tools, rock-drill bits, and lightweight armor. A wet-chemistry method is also investigated, which has much in common with that adopted by previous workers in the field. However, photo-voltaic properties do not measure up to expectations based on published data. A possible explanation is that the selected Ag concentrations are too high, so that recombination of holes and electrons occurs via a quantum-tunneling mechanism reduces photo-activity. Future work, therefore, will investigate lower concentrations of Ag dopant in TiO2, while also examining the effects of metastable states, including extended solid solution, amorphous, and semi-crystalline structures.

  8. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures.

    PubMed

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-03-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements. PMID:24457831

  9. Synthesis and characterization of cube-like Ag@AgCl-doped TiO2/fly ash cenospheres with enhanced visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Shaomin; Zhu, Jinglin; Yang, Qing; Xu, Pengpeng; Ge, Jianhua; Guo, Xuetao

    2016-03-01

    A cube-like Ag@AgCl-doped TiO2/fly ash cenosphere composite (denoted Ag@AgCl-TiO2/fly ash cenospheres) was successfully synthesized via a two-step approach. The as-prepared catalysts were characterized by scanning electron microscopy, X-ray diffraction, diffuse reflectance ultraviolet-visible spectroscopy, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy. The photocatalytic experiment showed that the rhodamine B degradation rate with Ag@AgCl-TiO2/fly ash cenospheres was 1.56 and 1.33 times higher than that with AgCl-TiO2/fly ash cenospheres and Ag@AgCl, respectively. The degradation ratio of rhodamine B with Ag@AgCl-TiO2/fly ash cenospheres was nearly 100% within 120 min under visible light. Analysis of active species indicated that radO2- and h+ dominated the reaction, and radOH participated in the photocatalytic reactions as an active species. A mechanism for the photocatalytic degradation by the Ag@AgCl-TiO2/fly-ash cenospheres was also proposed based on the experimental results.

  10. Improving the visible light photocatalytic activity of mesoporous TiO2 via the synergetic effects of B doping and Ag loading

    NASA Astrophysics Data System (ADS)

    Tian, Baozhu; Shao, Zhimang; Ma, Yunfei; Zhang, Jinlong; Chen, Feng

    2011-11-01

    B-doped together with Ag-loaded mesoporous TiO2 (Ag/B-TiO2) was prepared by a two-step hydrothermal method in the presence of boric acid, triblock copolymer surfactant, and silver nitrate, followed by heat treatment. The obtained samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption. It was revealed that all samples consist of highly crystalline anatase with mesoporous structure. For Ag/B-TiO2, B was doped into TiO2 matrix in the form of both interstitial B and substitutional B while Ag was deposited on the surface of B-TiO2 in the form of metallic silver. Compared with the single B-doped or Ag-loaded TiO2 one, mesoporous Ag/B-TiO2 exhibits much higher visible light photocatalytic activity for the degradation of Rhodamine 6G, which can be ascribed to the synergistic effects of B doping and Ag loading by narrowing the band gap of the photocatalyst and preventing the fast recombination of the photogenerated charge carriers, respectively.

  11. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures

    NASA Astrophysics Data System (ADS)

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-02-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements.TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped

  12. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens.

    PubMed

    Boxi, Siddhartha Sankar; Mukherjee, Khushi; Paria, Santanu

    2016-02-26

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated (•)OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling. PMID:26808118

  13. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens

    NASA Astrophysics Data System (ADS)

    Sankar Boxi, Siddhartha; Mukherjee, Khushi; Paria, Santanu

    2016-02-01

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated •OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.

  14. Enhanced photo-catalytic activity of Sr and Ag co-doped TiO2 nanoparticles for the degradation of Direct Green-6 and Reactive Blue-160 under UV & visible light.

    PubMed

    Naraginti, Saraschandra; Thejaswini, T V L; Prabhakaran, D; Sivakumar, A; Satyanarayana, V S V; Arun Prasad, A S

    2015-10-01

    This work is focused on sol-gel synthesis of silver and strontium co-doped TiO2 nanoparticles and their utilization as photo-catalysts in degradation of two textile dyes. Effect of pH, intensity of light, amount of photo-catalyst, concentration of dye, sensitizers, etc., were studied to optimize conditions for obtaining enhanced photo-catalytic activity of synthesized nanoparticles. XRD, BET, HR-TEM, EDAX and UV-Vis (diffused reflectance mode) techniques were used to characterize the nanoparticles. Interestingly, band gap of Sr and Ag co-doped TiO2 nanoparticles showed considerable narrowing (2.6 eV) when compared to Ag doped TiO2 (2.7 eV) and undoped TiO2 (3.17 eV) nanoparticles. Incorporation of Ag and Sr in the lattice of TiO2 could bring isolated energy levels near conduction and valence bands thus narrowing band gap. The XRD analysis shows that both Ag and Sr nanoparticles are finely dispersed on the surface of titania framework, without disturbing its crystalline structure. TEM images indicate that representative grain sizes of Ag-doped TiO2 & Sr and Ag co-doped TiO2 nanoparticles are in the range of 8-20 nm and 11-25 nm, respectively. Effective degradation of Direct Green-6 (DG-6) and Reactive Blue-160 (RB-160) under UV and visible light has been achieved using the photo-catalysts. Sr and Ag co-doped TiO2 photo-catalysts showed higher catalytic activity during degradation process in visible region when compared to Ag-doped and undoped TiO2 nanoparticles which could be attributed to the interactive effect caused by band gap narrowing and enhancement in charge separation. For confirming degradation of the dyes, total organic carbon (TOC) content was monitored periodically. PMID:25983059

  15. Visible-Light-Responsive Photocatalysis: Ag-Doped TiO2 Catalyst Development and Reactor Design Testing

    NASA Technical Reports Server (NTRS)

    Coutts, Janelle L.; Hintze, Paul E.; Meier, Anne; Shah, Malay G.; Devor, Robert W.; Surma, Jan M.; Maloney, Phillip R.; Bauer, Brint M.; Mazyck, David W.

    2016-01-01

    In recent years, the alteration of titanium dioxide to become visible-light-responsive (VLR) has been a major focus in the field of photocatalysis. Currently, bare titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Hg-vapor fluorescent light sources are used in photocatalytic oxidation (PCO) reactors to provide adequate levels of ultraviolet light for catalyst activation; these mercury-containing lamps, however, hinder the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. VLR-TiO2 would allow for use of ambient visible solar radiation or highly efficient visible wavelength LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Over the past three years, Kennedy Space Center has developed a VLR Ag-doped TiO2 catalyst with a band gap of 2.72 eV and promising photocatalytic activity. Catalyst immobilization techniques, including incorporation of the catalyst into a sorbent material, were examined. Extensive modeling of a reactor test bed mimicking air duct work with throughput similar to that seen on the International Space Station was completed to determine optimal reactor design. A bench-scale reactor with the novel catalyst and high-efficiency blue LEDs was challenged with several common volatile organic compounds (VOCs) found in ISS cabin air to evaluate the system's ability to perform high-throughput trace contaminant removal. The ultimate goal for this testing was to determine if the unit would be useful in pre-heat exchanger operations to lessen condensed VOCs in recovered water thus lowering the burden of VOC removal for water purification systems.

  16. Tuning the charge state of Ag and Au atoms and clusters deposited on oxide surfaces by doping: a DFT study of the adsorption properties of nitrogen- and niobium-doped TiO2 and ZrO2.

    PubMed

    Schlexer, Philomena; Ruiz Puigdollers, Antonio; Pacchioni, Gianfranco

    2015-09-14

    The charge state of Ag and Au atoms and clusters (Ag4 and Au4, Ag5 and Au5) adsorbed on defective TiO2 anatase(101) and tetragonal ZrO2(101) has been systematically investigated as a function of oxide doping and defectivity using a DFT+U approach. As intrinsic defects, we have considered the presence of oxygen vacancies. As extrinsic defects, substitutional nitrogen- and niobium-doping have been investigated, respectively. Both surface and sub-surface defects and dopants have been considered. Whereas on surfaces with oxygen vacancies or Nb-doping, atoms and clusters may become negatively charged, N-doping always leads to the formation of positively charged adsorbates, independently of the supporting material (TiO2 or ZrO2). This suggests the possibility to tune the electronic properties of supported metal clusters by selective doping of the oxide support, an effect that may result in complete changes in chemical reactivity. PMID:26248205

  17. Evolution of structural and magnetic properties of Co-doped TiO2 thin films irradiated with 100 MeV Ag7+ ions

    NASA Astrophysics Data System (ADS)

    Mohanty, P.; Singh, V. P.; Mishra, N. C.; Ojha, S.; Kanjilal, D.; Rath, Chandana

    2014-08-01

    In continuation to our earlier studies where we have shown room temperature ferromagnetism observed in TiO2 and Co-doped TiO2 (CTO) thin films independent of their phase (Mohanty et al 2012 J. Phys. D: Appl. Phys. 45 325301), here the modifications in structure and magnetic properties in CTO thin films using 100 MeV Ag7+ ion irradiation are reported. Owing to the important role of defects in tailoring the magnetic properties of the material, we vary the ion fluence from 5 × 1011 to 1 × 1012 ions cm-2 to create post-deposition defects. While the film deposited under 0.1 mTorr oxygen partial pressure retains its crystallinity showing radiation-resistant behaviour even at a fluence of 1 × 1012 ions cm-2, films deposited under 1 to 300 mTorr oxygen partial pressure becomes almost amorphous at the same fluence. Using Poisson's law, the diameter of the amorphized region surrounding the ion path is calculated to be ˜4.2 nm from the x-ray diffraction peak intensity ((1 1 0) for rutile phase) as a function of ion fluence. The saturation magnetization (Ms) decreases exponentially similar to the decrease in x-ray peak intensity with fluence, indicating magnetic disordered region surrounding the ion path. The diameter of the magnetic disordered region is found to be ˜6.6 nm which is larger than the diameter of the amorphized latent track. Therefore, it is confirmed that swift heavy ion irradiation induces a more significant magnetic disorder than the structural disorder.

  18. Fabrication of pure and Ag-doped TiO2 nanorods and study of the lattice strain and the activation energy of the crystalline phases

    NASA Astrophysics Data System (ADS)

    Riazian, Mehran; Rad, Shima Daliri; Azinabadi, Reza Ramezani

    2013-02-01

    TiO2 nanorods can be used as dye-sensitized solar cells and as various sensors and photocatalysts. These nanorods are synthesized by using a thermal corrosion process in a NaOH solution at 200 °C with TiO2 powder as a source material. In the present work, the synthesis of TiO2 nanorods in anatase, rutile and Ti8O15 phases and the synthesis of TiO2 nanorods by using the sol-gel method and alkaline corrosion to incorporate silver and silver-oxide dopants are reported. The morphologies and the crystalline structures of the TiO2 nanorods are characterized using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), tunneling electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The obtained results show an aggregation structure at high calcining temperatures with spherical particles and with Ti-O-Ti, Ti-O and Ag-O bonds. The effects of the chemical composition and the calcining temperature on the surface topography, lattice strain and phase crystallization are studied. The activation energy (E) of nanoparticle formation in a pure state during thermal treatment is calculated.

  19. 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.

  20. Effect of Erbium on the Photocatalytic Activity of TiO2 /Ag Nanocomposites under Visible Light Irradiation.

    PubMed

    Prakash, Natarajan; Karthikeyan, Rajan; Thangaraju, Dheivasigamani; Navaneethan, Mani; Arivanandhan, Mukannan; Koyama, Tadanobu; Hayakawa, Yasuhiro

    2015-10-01

    Erbium co-doped TiO2 /Ag catalysts are synthesized by using a simple, one-step solvothermal method and characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Raman analysis, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The catalysts exhibit anatase crystal structures with increased visible light absorption compared with pure TiO2 . Enhanced photocatalytic activity is observed with Er co-doped TiO2 /Ag nanocomposites for Rhodamine B degradation under visible light irradiation. The photocatalytic activity of 1 % Er co-doped TiO2 /Ag is much higher than that of TiO2 /Ag, TiO2 /Er, pure TiO2 , and commercial Degussa P25. The kinetics of the degradation process are studied and the pseudo-first-order rate constant (k) and half-life time (t1/2 ) of the reaction are calculated. The enhanced activity might be accredited to the efficient separation of electron-hole pairs by silver and higher visible light absorption of TiO2 induced by Er. PMID:26274932

  1. Synthesis and visible light photoactivity of anatase Ag, and garlic loaded TiO2 nanocrystalline catalyst

    EPA Science Inventory

    An excellent visible light activated Ag and S doped TiO2 nanocatalyst was prepared by using AgNO3 and garlic (Allium sativum) as Ag+ and sulfur sources, respectively. The catalyst resisted the change from anatase to rutile phase even at calcination at 700 oC. The photocatalytic e...

  2. Antibacterial activity of single crystalline silver-doped anatase TiO2 nanowire arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Xiangyu; Li, Meng; He, Xiaojing; Hang, Ruiqiang; Huang, Xiaobo; Wang, Yueyue; Yao, Xiaohong; Tang, Bin

    2016-05-01

    Well-ordered, one-dimensional silver-doped anatase TiO2 nanowire (AgNW) arrays have been prepared through a hydrothermal growth process on the sputtering-deposited AgTi layers. Electron microscope analyses reveal that the as-synthesized AgNW arrays exhibit a single crystalline phase with highly uniform morphologies, diameters ranging from 85 to 95 nm, and lengths of about 11 μm. Silver is found to be doped into TiO2 nanowire evenly and mainly exists in the zerovalent state. The AgNW arrays show excellent efficient antibacterial activity against Escherichia coli (E. coli), and all of the bacteria can be killed within 1 h. Additionally, the AgNW arrays can still kill E. coli after immersion for 60 days, suggesting the long-term antibacterial property. The technique reported here is environmental friendly for formation of silver-containing nanostructure without using any toxic organic solvents.

  3. 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.

  4. 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

  5. Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique.

    PubMed

    Achamo, Temesgen; Yadav, O P

    2016-01-01

    Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO2) was prepared by using sol-gel-synthesized Ag-doped TiO2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. As-synthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Average crystallite size of the studied photocatalysts was within 39-46 nm. Whereas doped Ag in TiO2 minimized the photogenerated electron-hole recombination, doped N and P extended its photoabsorption edge to visible region. Tridoping of Ag, N, and P in TiO2 exhibited synergetic effect toward enhancing its photocatalytic degradation of 4-nitrophenol (4-NP), separately, under UV and visible irradiations. At three hours, degradations of 4-NP over Ag-N-P-tridoped TiO2 under UV and visible radiations were 73.8 and 98.1%, respectively. PMID:27081309

  6. 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.

  7. Plasmonic TiO2/AgBr/Ag ternary composite nanosphere with heterojunction structure for advanced visible light photocatalyst

    NASA Astrophysics Data System (ADS)

    Dai, Kai; Li, Dongpei; Lu, Luhua; Liu, Qi; Liang, Changhao; Lv, Jiali; Zhu, Guangping

    2014-09-01

    In this work, TiO2/AgBr/Ag ternary composite nanosphere photocatalyst has been synthesized by in situ deposition of AgBr onto hollow spherical TiO2 template and followed by sun light reduction of AgBr into AgBr/Ag. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images have shown that the diameter of hollow TiO2 nanospheres is 250-350 nm and AgBr/Ag nanoparticles are well dispersed on the outer surface of TiO2 nanosphere. UV-vis spectrum analysis has shown largely improved visible light absorption of this ternary composite, in comparison to pure TiO2 and AgBr. The building-in AgBr/Ag, TiO2/AgBr and TiO2/Ag junctions within the ternary composite enhanced the visible light absorption because of plasmonic resonance and narrow bandgap. The pseudo-first-order rate constant kapp of the TiO2/AgBr/Ag ternary composite for methylene blue photodegradation displays 24.5 times and 3.3 times than the pure TiO2 nanosphere and AgBr/Ag nanoparticles, respectively. Furthermore, the stability of TiO2/AgBr/Ag ternary composite is characterized through cyclic photocatalytic test. Results indicate that 92.7% of photocatalytic degradation can be achieved by TiO2/AgBr/Ag ternary composite even after five recycles.

  8. 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.

  9. Preparation and characterization of Cu-doped TiO2 materials for electrochemical, photoelectrochemical, and photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Ganesh, Ibram; Kumar, Polkampally P.; Annapoorna, Ibram; Sumliner, Jordan M.; Ramakrishna, Mantripragada; Hebalkar, Neha Y.; Padmanabham, Gade; Sundararajan, Govindan

    2014-02-01

    The Cu-doped TiO2 (Cu = 0-50 wt.%) powders and thin films were prepared by following a homogeneous co-precipitation method and sol-gel dip-coating technique, respectively, and were treated through 400-800 °C, and then thoroughly investigated by following various characterization techniques. The characterization results suggest that the pure TiO2 powder formed at 550 °C is in rutile phase, whereas the 0.1-10 wt.% Cu-doped TiO2 powders formed at 550 °C are mainly in anatase phase. These latter powders possess low band-gap energies (3.247-3.265 eV) and flat-band potentials amenable to water oxidation reaction. The 0.5-wt.% Cu-doped TiO2 thin film formed at 550 °C exhibited n-type semiconducting behavior and considerable photocurrent among various investigated powders. The CO2 reduction with a Faradaic efficiency of 82% and ˜ 96% CO selectivity in a two-compartment electrochemical cell was noted at -2500 mV (vs. Ag/Ag+) on pre-reduced (at -2000 mV vs. Ag/AgCl) 50 wt.% Cu-doped TiO2 thin film electrode in conjunction with an ionic liquid. The UV-light-induced TiO2 was found to be responsible for photocatalytic methylene blue (MB) degradation, and TiO2 is not sensitized by MB. The in situ formed compounds of TiO2 and CuO/Cu2O were found to absorb visible light, but showed little visible-light-induced photocatalytic activity.

  10. 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

  11. 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

  12. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Feasibility of silver doped TiO2/glass fiber photocatalyst under visible irradiation as an indoor air germicide.

    PubMed

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-03-01

    This study investigated the feasibility of using Ag-TiO2 photocatalyst supported on glass fiber (Ag-TiO2/GF) prepared by a sol-gel method as an indoor air germicide. An experimental model was designed to investigate the bacterial disinfection efficiency of Staphylococcus (Staph), the most popular bacterium in hospitals in Korea, by the Ag-TiO2/GF photocatalyst. The silver content in Ag/TiO2 was altered from 1 to 10% to investigate the optimal ratio of Ag doped on TiO2/glass fiber (TiO2/GF) for photocatalytic disinfection of Staph. This study confirmed that Ag in Ag-TiO2/GF could work as an electron sink or donor to increase photocatalytic activity and promote the charge separation of electron-hole pairs generated from TiO2 after photon absorption. Ag also acts as an intermediate agent for the transfer of photo-generated electrons from the valence band of TiO2 to an acceptor (O2 gas) to promote photo-oxidation processes. The photocatalytic disinfection activity of Ag-TiO2/GF under visible light increased with the increase in silver content up to 7.5% and then slightly decreased with further increasing silver content. The highest disinfection efficiency and disinfection capacity of Staph using 7.5% Ag-TiO2/GF were 75.23% and 20 (CFU∙s-1∙cm-2) respectively. The medium level of humidity of 60% ± 5% showed better photocatalytic disinfection than the lower (40% ± 5%) or higher (80% ± 5%) levels. PMID:24658408

  19. Feasibility of Silver Doped TiO2/Glass Fiber Photocatalyst under Visible Irradiation as an Indoor Air Germicide

    PubMed Central

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-01-01

    This study investigated the feasibility of using Ag-TiO2 photocatalyst supported on glass fiber (Ag-TiO2/GF) prepared by a sol-gel method as an indoor air germicide. An experimental model was designed to investigate the bacterial disinfection efficiency of Staphylococcus (Staph), the most popular bacterium in hospitals in Korea, by the Ag-TiO2/GF photocatalyst. The silver content in Ag/TiO2 was altered from 1 to 10% to investigate the optimal ratio of Ag doped on TiO2/glass fiber (TiO2/GF) for photocatalytic disinfection of Staph. This study confirmed that Ag in Ag-TiO2/GF could work as an electron sink or donor to increase photocatalytic activity and promote the charge separation of electron-hole pairs generated from TiO2 after photon absorption. Ag also acts as an intermediate agent for the transfer of photo-generated electrons from the valence band of TiO2 to an acceptor (O2 gas) to promote photo-oxidation processes. The photocatalytic disinfection activity of Ag-TiO2/GF under visible light increased with the increase in silver content up to 7.5% and then slightly decreased with further increasing silver content. The highest disinfection efficiency and disinfection capacity of Staph using 7.5% Ag-TiO2/GF were 75.23% and 20 (CFU∙s−1∙cm−2) respectively. The medium level of humidity of 60% ± 5% showed better photocatalytic disinfection than the lower (40% ± 5%) or higher (80% ± 5%) levels. PMID:24658408

  20. Doping and compensation in Nb-doped anatase and rutile TiO2

    NASA Astrophysics Data System (ADS)

    Lee, Hsin-Yi; Robertson, John

    2013-06-01

    The substitutional Nb donor states in anatase and rutile TiO2 are calculated using the screened exchange hybrid density functional. The calculations find that Nb forms a shallow state in anatase and a deep state in rutile TiO2, as in experiment. Donors in anatase are found to become compensated in O-rich conditions because oxygen interstitial acceptors acquire a negative formation energy for Fermi energies high in the band gap. O-poor conditions permit doping, not by creating O vacancies but by inhibiting the formation of oxygen interstitials which compensate doping.

  1. 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

  2. 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.

  3. Photocatalysis with chromium-doped TiO2: bulk and surface doping.

    PubMed

    Ould-Chikh, Samy; Proux, Olivier; Afanasiev, Pavel; Khrouz, Lhoussain; Hedhili, Mohamed N; Anjum, Dalaver H; Harb, Moussab; Geantet, Christophe; Basset, Jean-Marie; Puzenat, Eric

    2014-05-01

    The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts. PMID:24737636

  4. 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

  5. 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

  6. Enhanced hydrogen evolution from water splitting using Fe-Ni codoped and Ag deposited anatase TiO2 synthesized by solvothermal method

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Liu, Enzhou; Liang, Xuhua; Hu, Xiaoyun; Fan, Jun

    2015-08-01

    In this paper, the Fe-Ni co-doped and Ag deposited anatase TiO2 (Fe-Ni/Ag/TiO2) nanocomposites were successfully prepared by a simple one-pot solvothermal approach. The investigations indicated that all as-prepared TiO2 samples were single anatase phase, and the impurity level was generated due to the Fe3+ or Ni2+ being located in the intrinsic band gap of TiO2, while the Ag+ ions could be transformed into metallic silver due to the reduction reaction and then loaded onto the surface of TiO2. Compared with pure TiO2, Fe-Ni/Ag/TiO2 composites with the sizes of Ag nanoparticles from 1.0 to 3.0 nm displayed the well optical property including higher visible light absorption activity and lower electron-hole pair recombination rate, and its absorption wavelength edge moved remarkably with a red shift to 700 nm. The photocatalytic water splitting was performed to produce H2 over the samples, and the experimental results indicate that Fe-Ni/Ag/TiO2 composites presented the highest H2 evolution rate, it can reach up to 793.86 μmol h-1 gcat-1 (λ > 400 nm for 6 h, energy efficiency is 0.25%), which was much higher than that of pure TiO2 for 9.57 μmol h-1 gcat-1. In addition, a tentative photocatalytic mechanism is proposed to understand the enhancement mechanism over Fe-Ni codoped and Ag deposited anatase TiO2.

  7. 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.

  8. Fabrication of plasmonic AgBr/Ag nanoparticles-sensitized TiO2 nanotube arrays and their enhanced photo-conversion and photoelectrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Qingyao; Qiao, Jianlei; Jin, Rencheng; Xu, Xiaohui; Gao, Shanmin

    2015-03-01

    Plasmonic photosensitizer AgBr/Ag nanospheres supported on TiO2 nanotube arrays (TiO2 NTs) are prepared by successive ionic layer adsorption and reaction (SILAR) technique followed by photoreduction methods. The structural and surface morphological properties of AgBr/Ag nanoparticles sensitized TiO2 NTs and their photoelectrochemical performance are investigated and discussed. A detailed formation mechanism of the TiO2 NTs/AgBr/Ag is proposed. The TiO2 NTs/AgBr/Ag exhibit excellent photocurrent and photoelectrocatalytic activities under visible light irradiation. Efficient utilization of solar energy to create electron-hole pairs is attributed to the significant visible light response and surface plasmon resonance of Ag nanoparticles. This finding indicates that the high photosensitivity of the TiO2 NTs-based surface plasmon resonance materials could be applied toward the development of new plasmonic visible-light-sensitive photovoltaic fuel cells and photocatalysts.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.

    PubMed

    Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  15. 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).

  16. 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

  17. 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

  18. 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.

  19. 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

  20. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-02-01

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future.Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the

  1. 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

  2. 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

  3. Hydrothermal synthesis of Fe-doped TiO2 nanostructure photocatalyst

    NASA Astrophysics Data System (ADS)

    Nghia Nguyen, Van; Khoa Truong Nguyen, Ngoc; Nguyen, Phi Hung

    2011-09-01

    Fe-doped TiO2 catalyst was prepared by the hydrothermal method. The resulting nanopowders were characterized by x-ray diffraction, transmission electron microscopy and Raman and UV-visible spectroscopies. The photocatalytic activity of the Fe-doped TiO2 was tested by decomposition of methylene orange with a concentration of 10 mg l‑1 in aqueous solution. The obtained results showed that methylene orange was significantly degraded after irradiation for 90 min under a halogen lamp and sunlight. The doping effect on the photocatalytic activity of the iron-doped catalyst samples are discussed.

  4. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites.

    PubMed

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-03-01

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future. PMID:26884248

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

    PubMed Central

    2014-01-01

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

  6. 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.

  7. 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.

  8. 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.

  9. Antibacterial ability and osteogenic activity of porous Sr/Ag-containing TiO2 coatings.

    PubMed

    He, Xiaojing; Zhang, Xiangyu; Bai, Long; Hang, Ruiqiang; Huang, Xiaobo; Qin, Lin; Yao, Xiaohong; Tang, Bin

    2016-01-01

    Implant-associated infection and poor osseointegration remains a major clinical challenge in Ti-based implant materials. A versatile strategy to endow Ti-based implants with long-term antibacterial ability as well as better osteogenic activity is highly desirable for high quality implantation. Strontium (Sr) has been shown to be a significant element to favor bone growth by promoting new bone formation and inhibiting bone resorption. In this study, a novel duplex-treatment technique encompassing magnetron sputtering with micro-arc oxidation is utilized to fabricate porous Sr/Ag-containing TiO2 coatings loaded with different concentrations of Ag and Sr. All coatings are porous with pore size less than 5 µm. Ag is primarily distributed homogeneously inside the pores, and the concentrations of Ag in Sr/Ag-containing TiO2 coatings with low and high Ag contents are 0.40 at.% and 0.83 at.% respectively. We have demonstrated that this kind of coating displays long-lasting antibacterial ability even up to 28 d due to the incorporation of Ag. Further, Sr/Ag-containing TiO2 coatings with optimum Ag and Sr contents revealed good cytocompatibility, enhanced osteoblast spreading and osseointegration, which stemmed primarily from the synergistic effect exerted by the porous surface topography and the bioactive element Sr. However, this study has also identified, for the first time, that proper addition of Ag would further facilitate osteogenic effects. Besides, Sr may be able to alleviate the potential cytotoxic effect of excessive Ag. Thus, integration of optimum functional elements Ag and Sr into Ti-based implant materials would be expected to expedite osseointegration while simultaneously sustaining long-term antibacterial activity, which would provide new insights for relevant fundamental investigations and biomedical applications. PMID:27508428

  10. 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.

  11. 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.

  12. 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.

  13. 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%).

  14. 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

  15. Modulating TiO2 photocatalyst by Al doping: Density functional theory approach

    NASA Astrophysics Data System (ADS)

    Zhao, Ya Fei; Li, Can; Lu, Song; Gong, Yin Yan; Niu, Leng Yuan; Liu, Xin Juan

    2016-06-01

    In this work, systematic study of the thermal stability, crystal structure and electronic properties of Al doped TiO2 were studied by the first principles calculations. The results showed that Al atoms preferentially occupying the interstitial site under Ti-rich condition, but substituting the Ti atom under O-rich condition. In contrast to pure TiO2, the values of VBM and CBM are reduced for Al substituting Ti doped mode, but increased for Al interstitial atom doped mode. Thus, we can modulate the preparation condition and dosage concentration for preparing the optimal photocatalyst.

  16. 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.

  17. 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

  18. 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.

  19. SiO2/TiO2/Ag multilayered microspheres: Preparation, characterization, and enhanced infrared radiation property

    NASA Astrophysics Data System (ADS)

    Ye, Xiaoyun; Cai, Shuguang; Zheng, Chan; Xiao, Xueqing; Hua, Nengbin; Huang, Yanyi

    2015-08-01

    SiO2/TiO2/Ag core-shell multilayered microspheres were successfully synthesized by the combination of anatase of TiO2 modification on the surfaces of SiO2 spheres and subsequent Ag nanoparticles deposition and Ag shell growth with face-centered cubic (fcc) Ag. The composites were characterized by TEM, FT-IR, UV-vis, Raman spectroscopy and XRD, respectively. The infrared emissivity values during 8-14 μm wavelengths of the composites were measured. The results revealed that TiO2 thin layers with the thickness of ∼10 nm were coated onto the SiO2 spheres of ∼220 nm in diameter. The thickness of the TiO2 layers was controlled by varying the amount of TBOT precursor. Homogeneous Ag nanoparticles of ∼20 nm in size were successfully deposited by ultrasound on the surfaces of SiO2/TiO2 composites, followed by complete covering of Ag shell. The infrared emissivity value of the SiO2/TiO2 composites was decreased than that of pure SiO2. Moreover, the introduction of the Ag brought the remarkably lower infrared emissivity value of the SiO2/TiO2/Ag multilayered microspheres with the lowest value down to 0.424. Strong chemical effects in the interface of SiO2/TiO2 core-shell composites and high reflection performance of the metal Ag are two decisive factors for the improved infrared radiation performance of the SiO2/TiO2/Ag multilayered microspheres.

  20. Influence of Ag-Au microstructure on the photoelectrocatalytic performance of TiO2 nanotube array photocatalysts.

    PubMed

    Wang, Qingyao; Wang, Xiaotong; Zhang, Miao; Li, Guihua; Gao, Shanmin; Li, Mingyang; Zhang, Yiqing

    2016-02-01

    In this work, vertically-aligned TiO2 nanotube arrays (TiO2 NTs) were grown on Ti substrates via a facile electrochemical anodization method followed by calcinations. Then, Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles were deposited on the obtained TiO2 NTs via UV reduction and displacement reaction, respectively. X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that Ag-Au alloy nanoparticles and Ag@Au core-shell nanoparticles grew uniformly on the walls of TiO2 NTs. Investigation results from removal of methyl orange (MO) and Cr(IV) ions indicated that the as-prepared bimetal plasmonic photocatalysts exhibited excellent photoelectrocatalytic (PEC) activities. The influences of Ag-Au alloy and core-shell microstructures on PEC properties of TiO2 NTs were investigated and the TiO2 NTs/Ag@Au photocatalyst showed more outstanding PEC removal efficiency than that of TiO2 NTs/Ag-Au due to the regular core-shell microstructure and low recombination of photogenerated electrons and holes. PMID:26555961

  1. 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.

  2. 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

  3. Effect of silver-doping on the crystal structure, morphology and photocatalytic activity of TiO2 nanofibers

    NASA Astrophysics Data System (ADS)

    Barakat, N. A. M.; Kim, H. Y.

    2012-09-01

    In this study, effect of sliver-doping on the crystal structure, the nanofibrous morphology and the photocatalytic activity of titanium oxide nanofibers have been investigated. Silver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600 °C. The results affirmed formation of silver-doped TiO2 nanofibers composed of anatase and rutile when the silver nitrate content in the original electrospun solution was more than 3 wt%. The rutile phase content was directly proportional with the AgNO3 concentration in the electrospun solution. Negative impact of the silver-doping on the nanofibrous morphology was observed as increase the silver content caused to decrease the aspect ratio, i.e. producing nanorods rather nanofibers. However, silver-doping leads to modify the surface roughness. Study of the photocatalytic degradation of methylene blue dye clarified that increase the silver content strongly enhances the dye oxidation process.

  4. Gamma Radiation Monitoring Through Thin Film of ClAlPc Doped With TiO2

    NASA Astrophysics Data System (ADS)

    Roy, M. S.; Gautam, A. K.; Kumar, M.; Prasad, N.; Janu, Y.; Deol, Y. S.; Mishra, R. K.; Choudhary, G. R.; Sadh, A. K.

    2008-04-01

    Chloroaluminum phthalocyanine (ClAlPc) synthesized by adopting focused microwave synthesis approach was doped with nanocrystalline TiO2 (5% by weight) and developed into the thin film sandwiched device having ITO/ClAlPc:TiO2/Ag Schottky configuration by spin coating technique covering 1 cm2 as an active area. The so fabricated device having initial dark current of the order of 0.2 5 m A was exposed to variable dose of gamma radiation ranging from lcGy to 10 Gy at a dose rate of 1 Gy/hour. The experimental observation reveals the generation of localized traps leading to structural disorder within the solid material. Doping with TiO2 enhances the surface area of the film which in tern improves sensitivity of device to wider dose rage. Exposure of the device to variable dose of gamma radiation imparts decrease in forward bias current and capacitance characteristics with increase in radiation dose. Also, absorbance characteristics of the Al Pc: TiO2 was analyzed before & after exposure to radiation which reveals that absorbance decreases with radiation dose leading to decrease in optical band gap.

  5. 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

  6. 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

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

    PubMed

    Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

    2016-02-01

    This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2. PMID:26499197

  8. 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

  9. 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.

  10. Ag-loaded TiO2/reduced graphene oxide nanocomposites for enhanced visible-light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Vasilaki, E.; Georgaki, I.; Vernardou, D.; Vamvakaki, M.; Katsarakis, N.

    2015-10-01

    In this work, Ag nanoparticles were loaded by chemical reduction onto TiO2 P25 under different loadings ranging from 1 up to 4 wt% and hydrothermally deposited on reduced graphene oxide sheets. Chemical reduction was determined to be an effective preparation approach for Ag attachment to titania, leading to the formation of small silver nanoparticles with an average diameter of 4.2 nm. The photocatalytic performance of the hybrid nanocomposite materials was evaluated via methylene blue (MB) dye removal under visible-light irradiation. The rate of dye decolorization was found to depend on the metal loading, showing an increase till a threshold value of 3 wt%, above which the rate drops. Next, the as prepared sample of TiO2/Ag of better photocatalytic response, i.e., at a 3 wt% loading value, was hydrothermally deposited on a platform of reduced graphene oxide (rGO) of tunable content (mass ratio). TiO2/Ag/rGO coupled nanocomposite presented significantly enhanced photocatalytic activity compared to the TiO2/Ag, TiO2/rGO composites and bare P25 titania semiconductor photocatalysts. In particular, after 45 min of irradiation almost complete decolorization of the dye was observed for the TiO2/Ag/rGO nanocatalyst, while the respective removal efficiency was 92% for TiO2/Ag, 93% for TiO2/rGO and only 80% for the bare TiO2 nanoparticles. This simple step by step preparation strategy allows for optimum exploitation of the advanced properties of metal plasmonic effect and reduced graphene oxide as the critical host for boosting the overall photocatalytic activity towards visible-light.

  11. A hydrothermal synthesis of Pr3+ doped mesoporous TiO2 for UV light photocatalysis.

    PubMed

    Wang, Yong; Chen, Guihua; Shen, Qianhong; Yang, Hui; Li, Liquan; Song, Yanjiang

    2014-07-01

    Pr3+ doped mesoporous TiO2 photocatalysts with a different molar ratio of Pr to Ti were prepared by a hydrothermal method using triblock copolymer as the template. The as-prepared samples were systematically characterized by X-ray diffraction, N2 adsorption-desorption, X-ray photoelectron spectra, transmission electron microscopy and UV-visible diffuse reflectance spectroscopy. The characterizations indicated all the samples had mesoporous structure and narrow pore size distribution. Pr3+ doping enlarged the surface area and decreased the crystallite size. The surface area of the samples varied from 136 to 170 m2/g, and the average crystallite size ranged between 5.04 and 7.60 nm. The effect of Pr3+ doping amount on the photocatalytic activity of mesoporous TiO2 was evaluated by the degradation of methyl orange under UV light irradiation. The results showed that the suitable amount of Pr3+ doped samples exhibited the higher photocatalytic activity than mesoporous TiO2. Among the samples, 1 at.% Pr3+ doped mesoporous TiO2 showed the highest photocatalytic activity. PMID:24757971

  12. Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

    PubMed

    Cheng, Zhi-Lin; Han, Shuai

    2016-01-01

    A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment. PMID:26877029

  13. Influence of Ce doping on optical and dielectric properties of TiO2

    NASA Astrophysics Data System (ADS)

    Naseem, Swaleha; Khan, Wasi; Naqvi, A. H.

    2016-05-01

    Rare earth ion (Ce) doped TiO2 and pure TiO2 nanostructured were prepared by sol gel acid modified technique and calcinated at 450°C. Microstructural studies and thermal analysis were carried by XRD and TGA respectively. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible spectroscopy and band gap energy was estimated 3.04 eV and 3.14 eV for pure and Ce doped TiO2 respectively. Room temperature dielectric constant (ɛ') decreases abruptly at lower frequencies owing to the charge transport relaxation. The observed behavior of the dielectric properties can be attributed on the basis of Koop's theory based on Maxwell-Wagner's two layer model in studied nanoparticles.

  14. Preparation of Fe-doped TiO2 nanoparticles immobilized on polyamide fabric

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Zhu, Hong

    2012-10-01

    A thin layer of nano-scaled Fe-doped TiO2 particles prepared by hydrothermal method is immobilized on the surface of polyamide 6 (PA6) fiber using tetrabutyl titanate as the precursor, ferric trichloride as the doping agent and chitosan as the dispersant agent. The morphology, crystal structure, thermal behavior, composition and chemical structure of PA6 fabric before and after treatments are characterized by means of scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry and thermal gravimetric analysis techniques. The properties of diffuse reflectance spectrum, tensile, air permeability, whiteness, yellowness and photocatalytic activity are also analyzed. It is found that the anatase phase Fe-doped TiO2 nanoparticles with crystal size of 12 nm or so are synthesized, and simultaneously grafted onto the fiber surface during the processing. Compared with the TiO2-coated fabric, the thermal stability of the Fe-doped TiO2-coated fabric changes a little. The absorption ability to ultraviolet (UV) rays and visible light is greatly improved. The breaking force and breaking elongation increase to some extent because of the shrinkage of fabric. The air permeability decreases distinctly. The color of PA6 fabric changes from white to light brownish because of the introduction of ferric trichloride. The photocatalytic activity of methylene blue decolorization is enhanced under sunlight and UV irradiation.

  15. Visible light induced photobleaching of methylene blue over melamine-doped TiO2 nanocatalyst

    EPA Science Inventory

    TiO2 doping with N-rich melamine produced a stable, active and visible light sentisized nanocatalyst that showed a remarkable efficiency towards the photobleaching of a model compound – methylene blue (MB) in aqueous solution. The photobleaching followed a mixed reaction order ki...

  16. Preparation and Characterization of Fe-Doped TiO2 Films Covered on Silicagel

    NASA Astrophysics Data System (ADS)

    Nghia, Nguyen Manh; Hue, Nguyen Thi; Thu, Ma Thi Anh; Len, Phung Thi; Thu, Vu Thi; Lam, Tran Dai

    2016-07-01

    This study describes sol-gel preparation of (TiO2:Fe x )/SiO2 ( x = 0-0.8%) on silicagel grains using titanium tetraisopropoxide and iron (III) chloride as titanium precursor and doping agent, respectively. The structural properties, morphology, and chemical composition of the samples were thoroughly studied using x-ray diffraction, field emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy, respectively. The results demonstrated the formation of highly pure anatase TiO2:Fe x crystals with diameters of several tens of nanometers. With increasing doping level, no significant change in porosity of TiO2 material was observed, whereas the decrease in crystalline size was easily recorded. In addition, the bandgap (observed by UV-Vis) was dramatically shifted from 2.9 eV to 1.7 eV as doping with TiO2 with Fe at doping content as low as 0.8%. The use of silicagel as a solid support to carry photocatalytic crystals enables recycling of the material. These findings represent a simple pathway to design reusable catalyst for highly effective water detoxification under visible illumination.

  17. Preparation and Characterization of Fe-Doped TiO2 Films Covered on Silicagel

    NASA Astrophysics Data System (ADS)

    Nghia, Nguyen Manh; Hue, Nguyen Thi; Thu, Ma Thi Anh; Len, Phung Thi; Thu, Vu Thi; Lam, Tran Dai

    2016-04-01

    This study describes sol-gel preparation of (TiO2:Fe x )/SiO2 (x = 0-0.8%) on silicagel grains using titanium tetraisopropoxide and iron (III) chloride as titanium precursor and doping agent, respectively. The structural properties, morphology, and chemical composition of the samples were thoroughly studied using x-ray diffraction, field emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy, respectively. The results demonstrated the formation of highly pure anatase TiO2:Fe x crystals with diameters of several tens of nanometers. With increasing doping level, no significant change in porosity of TiO2 material was observed, whereas the decrease in crystalline size was easily recorded. In addition, the bandgap (observed by UV-Vis) was dramatically shifted from 2.9 eV to 1.7 eV as doping with TiO2 with Fe at doping content as low as 0.8%. The use of silicagel as a solid support to carry photocatalytic crystals enables recycling of the material. These findings represent a simple pathway to design reusable catalyst for highly effective water detoxification under visible illumination.

  18. p-Type hydrogen sensing with Al- and V-doped TiO2 nanostructures

    PubMed Central

    2013-01-01

    Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, anatase TiO2 nanofilms doped with Al and V elements were fabricated through anodic oxidation of Ti6Al4V alloy and further annealing treatment. Hydrogen sensing behavior of the crystallized Ti-Al-V-O nanofilms at various working temperatures was investigated through exposure to 1,000 ppm H2. Different from n-type hydrogen sensing characteristics of undoped TiO2 nanotubes, the Al- and V-doped nanofilms presented a p-type hydrogen sensing behavior by showing increased resistance upon exposure to the hydrogen-containing atmosphere. The Ti-Al-V-O nanofilm annealed at 450°C was mainly composed of anatase phase, which was sensitive to hydrogen-containing atmosphere only at elevated temperatures. Annealing of the Ti-Al-V-O nanofilm at 550°C could increase the content of anatase phase in the oxide nanofilm and thus resulted in a good sensitivity and resistance recovery at both room temperature and elevated temperatures. The TiO2 nanofilms doped with Al and V elements shows great potential for use as a robust semiconducting hydrogen sensor. PMID:23311459

  19. 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

  20. Ag@helical chiral TiO2 nanofibers for visible light photocatalytic degradation of 17α-ethinylestradiol.

    PubMed

    Zhang, Chi; Li, Yi; Wang, Dawei; Zhang, Wenlong; Wang, Qing; Wang, Yuming; Wang, Peifang

    2015-07-01

    Ag-modified helical chiral TiO2 NFs (Ag@chiral TiO2 NFs) were fabricated and characterized by ultraviolet-visible absorption spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. This novel material exhibited efficient photocatalytic activity for the degradation of 17α-ethinylestradiol (EE2) in water under visible light irradiation with an optimum size of deposited silver nanoparticles (Ag NPs) in the range of 12 ∼ 14 nm. The pseudo-first-order rate constant (k obs) for EE2 photodegradation by Ag@chiral TiO2 NFs increased by up to a factor of 20.1 when compared with that of pure chiral TiO2 NFs. The high photocatalytic activity can be attributed to the interactions between helical chiral TiO2 NFs and surface plasmon resonance effect of Ag NPs. The new catalyst retains its photocatalytic activity at least up to five consecutive cycles. The results clearly demonstrate the feasibility of using Ag@chiral TiO2 NFs for the photocatalytic removal of EE2 and other endocrine-disrupting chemicals from water. PMID:25721529

  1. The preparation and characterization of La doped TiO 2 nanoparticles and their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liqiang, Jing; Xiaojun, Sun; Baifu, Xin; Baiqi, Wang; Weimin, Cai; Honggang, Fu

    2004-10-01

    In this paper, pure and La doped TiO2 nanoparticles with different La content were prepared by a sol-gel process using Ti (OC4H9)4 as raw material, and also were characterized by XRD, TG-DTA, TEM, XPS, DRS and Photoluminescence (PL) spectra. We mainly investigated the effects of calcining temperature and La content on the properties and the photocatalytic activity for degrading phenol of as-prepared TiO2 samples, and also discussed the relationships between PL spectra and photocatalytic activity as well as the mechanisms of La doping on TiO2 phase transformation. The results showed that La3+ did not enter into the crystal lattices of TiO2 and was uniformly dispersed onto TiO2 as the form of La2O3 particles with small size, which possibly made La dopant have a great inhibition on TiO2 phase transformation; La dopant did not give rise to a new PL signal, but it could improve the intensity of PL spectra with a appropriate La content, which was possibly attributed to the increase in the content of surface oxygen vacancies and defects after doping La; La doped TiO2 nanoparticles calcined at 600°C exhibited higher photocatalytic activity, indicating that 600°C was an appropriate calcination temperature. The order of photocatalytic activity of La doped TiO2 samples with different La content was as following: 1>1.5>3>0.5>5>0 mol%, which was the same as the order of their PL intensity, namely, the stronger the PL intensity, the higher the photocatalytic activity, demonstrating that there were certain relationships between PL spectra and photocatalytic activity. This could be explained by the points that PL spectra mainly resulted from surface oxygen vacancies and defects during the process of PL, while surface oxygen vacancies and defects could be favorable in capturing the photoinduced electrons during the process of photocatalytic reactions.

  2. Microstructure and dielectric properties of (Nb + In) co-doped rutile TiO2 ceramics

    NASA Astrophysics Data System (ADS)

    Li, Jinglei; Li, Fei; Zhuang, Yongyong; Jin, Li; Wang, Linghang; Wei, Xiaoyong; Xu, Zhuo; Zhang, Shujun

    2014-08-01

    The (Nb + In) co-doped TiO2 ceramics recently attracted considerable attention due to their colossal dielectric permittivity (CP) (˜100,000) and low dielectric loss (˜0.05). In this research, the 0.5 mol. % In-only, 0.5 mol. % Nb-only, and 0.5-7 mol. % (Nb + In) co-doped TiO2 ceramics were synthesized by standard conventional solid-state reaction method. Microstructure studies showed that all samples were in pure rutile phase. The Nb and In ions were homogeneously distributed in the grain and grain boundary. Impedance spectroscopy and I-V behavior analysis demonstrated that the ceramics may compose of semiconducting grains and insulating grain boundaries. The high conductivity of grain was associated with the reduction of Ti4+ ions to Ti3+ ions, while the migration of oxygen vacancy may account for the conductivity of grain boundary. The effects of annealing treatment and bias filed on electrical properties were investigated for co-doped TiO2 ceramics, where the electric behaviors of samples were found to be susceptible to the annealing treatment and bias field. The internal-barrier-layer-capacitance mechanism was used to explain the CP phenomenon, the effect of annealing treatment and nonlinear I-V behavior for co-doped rutile TiO2 ceramics. Compared with CaCu3Ti4O12 ceramics, the high activation energy of co-doped rutile TiO2 (3.05 eV for grain boundary) was thought to be responsible for the low dielectric loss.

  3. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    NASA Astrophysics Data System (ADS)

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-01

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1

  4. Research Update: Doping ZnO and TiO2 for solar cells

    NASA Astrophysics Data System (ADS)

    Hoye, Robert L. Z.; Musselman, Kevin P.; MacManus-Driscoll, Judith L.

    2013-12-01

    ZnO and TiO2 are two of the most commonly used n-type metal oxide semiconductors in new generation solar cells due to their abundance, low-cost, and stability. ZnO and TiO2 can be used as active layers, photoanodes, buffer layers, transparent conducting oxides, hole-blocking layers, and intermediate layers. Doping is essential to tailor the materials properties for each application. The dopants used and their impact in solar cells are reviewed. In addition, the advantages, disadvantages, and commercial potential of the various fabrication methods of these oxides are presented.

  5. Revisiting the mechanism of photocatalytic activities in N-doped TiO2

    NASA Astrophysics Data System (ADS)

    Umezawa, Naoto; Ye, Jinhua

    2012-02-01

    Photocatalysis possesses a great potential for environmental remediation and fuel production [1]. Nitrogen doped TiO2 is a well-known visible-light sensitive photocatalyst where deep impurity states associated with substitutional nitrogen at oxygen sites (NO) are believed to be the source of the red shift in photo-absorption edge. However, such a deep level should trap hole carriers, degrading oxidation process. The contradiction between the deep NO level and rather a high oxidation power of N-doped TiO2 has been an unsolved puzzle. Here, we propose a convincing mechanism which successfully solves the riddle. NO strongly binds with a titanium atom at an interstitial site, forming a defect-impurity band, which consists of bonding and anti-bonding states of nitrogen p and titanium d and narrows the band gap. Such a newly formed band, which is connected to the valence band maximum of the host TiO2, becomes the migration path of photo-induced hole carriers, assisting carrier transfer to the surface. This clearly explains the photocatalytic activity of N-doped TiO2 both for the visible-light absorption and the oxidation reaction. [1] Hua Tong, Shuxin Ouyang, Yingpu Bi, Naoto Umezawa, Mitsutake Oshikiri, and Jinhua Ye, Advanced Materials DOI: 10.1002/adma.20110275

  6. Preparation and photocatalytic activity of nanoglued Sn-doped TiO2.

    PubMed

    Li, Xiang; Xiong, Rongchun; Wei, Gang

    2009-05-30

    In this paper, Sn-doped TiO(2) photocatalyst was prepared and immobilized on a glass substrate using an about-to-gel SiO(2) sol as a nanoglue. The characterization of the Sn-doped TiO(2) by XRD showed that 5% Sn content is formed by anatase and rutile crystallites. Characterization of the nanoglued photocatalyst by the BET measurement, TEM, and SEM showed that the photocatalyst was a nanoporous material with a high-surface area. The Sn-doped TiO(2) was uniformly dispersed within the three-dimensional network of the silica in the form of nanoparticles. The nanoglued photocatalyst showed high photocatalytic activity during the degradation of penicillin under UV light. The effect of different Sn content on the amount of hydroxyl radical was discussed by using salicylic acid as probe molecules. The results show that an appropriate amount of Sn dopant can greatly increase the amount of hydroxyl radicals generated by TiO(2) nanoparticles, which are responsible for the obvious increase of photocatalytic activity. PMID:18834665

  7. Effect of doping on electronic structure and photocatalytic behavior of amorphous TiO2.

    PubMed

    Ghuman, Kulbir Kaur; Singh, Chandra Veer

    2013-11-27

    Visible light photocatalysts based on doped crystalline forms of titanium dioxide (TiO2) have attracted significant scientific attention in recent decades. Amorphous TiO2, despite many merits over crystalline phases, has not been studied as thoroughly. In this paper, an in-depth analysis of the electronic properties of doped amorphous TiO2 is performed using density functional theory with Hubbard's energy correction (DFT + U). Monodoping with p-type (N) and n-type (Nb) dopants shows appreciable bandgap reduction, but leads to recombination centers due to the presence of uncompensated charges. To resolve this issue, charge compensation via codoping is attempted. The charge compensated codoping not only reduces the bandgap by 0.4 eV but also eliminates the bandgap states present in monodoped systems responsible for charge carrier recombination. Furthermore, the localized tail states present in the aTiO2 system are eliminated to a large extent which leads to a decrease in the charge recombination and an increase in the charge migration. Thus, appropriate doping of amorphous TiO2 may lead to an alternative route for the development of visible light photocatalysts. PMID:24172752

  8. Effect of doping on electronic structure and photocatalytic behavior of amorphous TiO2

    NASA Astrophysics Data System (ADS)

    Ghuman, Kulbir Kaur; Veer Singh, Chandra

    2013-11-01

    Visible light photocatalysts based on doped crystalline forms of titanium dioxide (TiO2) have attracted significant scientific attention in recent decades. Amorphous TiO2, despite many merits over crystalline phases, has not been studied as thoroughly. In this paper, an in-depth analysis of the electronic properties of doped amorphous TiO2 is performed using density functional theory with Hubbard’s energy correction (DFT + U). Monodoping with p-type (N) and n-type (Nb) dopants shows appreciable bandgap reduction, but leads to recombination centers due to the presence of uncompensated charges. To resolve this issue, charge compensation via codoping is attempted. The charge compensated codoping not only reduces the bandgap by 0.4 eV but also eliminates the bandgap states present in monodoped systems responsible for charge carrier recombination. Furthermore, the localized tail states present in the aTiO2 system are eliminated to a large extent which leads to a decrease in the charge recombination and an increase in the charge migration. Thus, appropriate doping of amorphous TiO2 may lead to an alternative route for the development of visible light photocatalysts.

  9. Photocatalytic Activity of W-Doped TiO2 Nanofibers for Methylene Blue Dye Degradation.

    PubMed

    Song, Yo-Seung; Cho, Nam-Ihn; Lee, Myung-Hyun; Kim, Bae-Yeon; Lee, Deuk Yong

    2016-02-01

    Photocatalytic degradation of methylene blue (MB) in water was examined using W-doped TiO2 nanofibers prepared by a sol-gel derived electrospinning and subsequent calcination for 4 h at 550 degrees C. Different concentrations of W dopant in the range of 0 to 8 mol% were synthesized to evaluate the effect of W concentration on the photocatalytic activity of TiO2. XRD results indicated that the undoped TiO2 is composed of anatase and rutile phases. The rutile phase was transformed to anatase phase completely with the W doping. Among W-TiO2 catalysts, the 2 mol% W-TiO2 catalyst showed the highest MB degradation rate. The degradation kinetic constant increased from 1.04 x 10(-3) min(-1) to 3.54 x 10(-3) min(-1) with the increase of W doping from 0 to 2 mol%, but decreased down to 1.77 x 10(-3) min(-1) when the W content was 8 mol%. It can be concluded that the degradation of MB under UV radiation was more efficient with W-TiO2 catalysts than with pure TiO2- PMID:27433681

  10. Zirconium and silver co-doped TiO2 nanoparticles as visible light catalyst for reduction of 4-nitrophenol, degradation of methyl orange and methylene blue

    NASA Astrophysics Data System (ADS)

    Naraginti, Saraschandra; Stephen, Finian Bernard; Radhakrishnan, Adhithya; Sivakumar, A.

    2015-01-01

    Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst.

  11. Zirconium and silver co-doped TiO2 nanoparticles as visible light catalyst for reduction of 4-nitrophenol, degradation of methyl orange and methylene blue.

    PubMed

    Naraginti, Saraschandra; Stephen, Finian Bernard; Radhakrishnan, Adhithya; Sivakumar, A

    2015-01-25

    Catalytic activity of Zr and Ag co-doped TiO2 nanoparticles on the reduction of 4-nitrophenol, degradation of methylene blue and methyl orange was studied using sodium borohydride as reducing agent. The nanoparticles were characterized using X-ray diffraction, energy dispersive X-ray, high resolution transmission electron microscopy, selected area electron diffraction and UV-Vis spectroscopy. The rate of the reduction/degradation was found to increase with increasing amount of the photocatalyst which could be attributed to higher dispersity and small size of the nanoparticles. The catalytic activity of Zr and Ag co-doped TiO2 nanoparticles showed no significant difference even after recycling the catalyst four times indicating a promising potential for industrial application of the prepared photocatalyst. PMID:25150432

  12. Zirconium doped TiO2 thin films: A promising dielectric layer

    NASA Astrophysics Data System (ADS)

    Kumar, Arvind; Mondal, Sandip; Rao, K. S. R. Koteswara

    2016-05-01

    In the present work, we have fabricated the zirconium doped TiO2 thin (ZTO) films from a facile spin - coating method. The addition of Zirconium in TiO2 offers conduction band offset to Si and consequently decreased the leakage current density by approximately two orders as compared to pure TiO2 thin (TO) films. The ZTO thin film shows a high dielectric constant 27 with a very low leakage current density ˜10-8 A/cm2. The oxide capacitate, flat band voltage and change in flat band voltage are 172 pF, -1.19 V and 54 mV. The AFM analysis confirmed the compact and pore free flat surface. The RMS surface roughness is found to be 1.5 Å. The ellipsometry analysis also verified the fact with a high refractive index 2.21.

  13. N-doped TiO2/C nanocomposites and N-doped TiO2 synthesised at different thermal treatment temperatures with the same hydrothermal precursor.

    PubMed

    Wang, Jia; Fan, Chenyao; Ren, Zhimin; Fu, Xinxin; Qian, Guodong; Wang, Zhiyu

    2014-09-28

    A hydrothermal precursor was first obtained by isopropyl titanate reacting with tetramethylammonium hydroxide (TMAOH), which acts as a source of nitrogen and carbon. A facile post-thermal treatment was employed to enhance the crystallinity and visible light photocatalytic activity of the as-prepared precursor. The resulting products of post-thermal treatment between 200 °C and 700 °C display different colours from brown to white. Black N-doped TiO2 nanoparticles modified with carbon (denoted as N-TiO2/C) were obtained at 300 °C, while yellow N-doped TiO2 nanoparticles (denoted as N-TiO2) were obtained at 500 °C. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were applied to characterize N-TiO2/C, N-TiO2 and the evolution process during thermal treatment. The results show that for both N-TiO2/C and N-TiO2, nitrogen was doped into the lattice, thus narrowing the band gap and increasing the absorption in the visible light region. Moreover, for N-TiO2/C, the carbon species modified on the surface and between the nanocrystals enhanced the visible light harvesting and increased the adsorption of the dye in the photodegradation measurement. The photocatalytic performance under visible light irradiation is N-TiO2/C > N-TiO2 > undoped TiO2. PMID:25104087

  14. Charge and magnetic states of rutile TiO2 doped with Cr ions.

    PubMed

    Kim, Rokyeon; Cho, Suyeon; Park, Won-Goo; Cho, Deok-Yong; Oh, Se-Jung; Saint-Martin, Romuald; Berthet, Patrick; Park, Je-Geun; Yu, Jaejun

    2014-04-01

    We observe that the electronic and magnetic properties of Cr-doped rutile TiO2 single crystals are highly dependent on growth conditions. The ferromagnetic component of magnetic susceptibility is observed to be enhanced for samples grown under oxygen-rich conditions. To understand the charge state of Cr dopants and their role in response to an external magnetic field, we carry out density functional theory calculations for Cr-doped rutile TiO2. Using the results of formation energy calculations in the presence of oxygen vacancies and Cr atom substitution at the Ti sites, we demonstrate that the Cr3+ state is a source of Curie-Weiss-type magnetic response, whereas the Cr4+ defect states contribute to the ferromagnetic component. We also provide the electronic structures of various defect configurations and attempt to explain the optical and electronic properties of the Cr-doped system. PMID:24651728

  15. Reduced graphene oxide and Ag wrapped TiO2 photocatalyst for enhanced visible light photocatalysis

    NASA Astrophysics Data System (ADS)

    Leong, Kah Hon; Sim, Lan Ching; Bahnemann, Detlef; Jang, Min; Ibrahim, Shaliza; Saravanan, Pichiah

    2015-10-01

    A well-organised reduced graphene oxide (RGO) and silver (Ag) wrapped TiO2 nano-hybrid was successfully achieved through a facile and easy route. The inherent characteristics of the synthesized RGO-Ag/TiO2 were revealed through crystalline phase, morphology, chemical composition, Raman scattering, UV-visible absorption, and photoluminescence analyses. The adopted synthesis route significantly controlled the uniform formation of silver nanoparticles and contributed for the absorption of light in the visible spectrum through localized surface plasmon resonance effects. The wrapped RGO nanosheets triggered the electron mobility and promoted visible light shift towards red spectrum. The accomplishment of synergised effect of RGO and Ag well degraded Bisphenol A under visible light irradiation with a removal efficiency of 61.9%.

  16. TiO 2 nanopowders doped with boron and nitrogen for photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Gombac, V.; De Rogatis, L.; Gasparotto, A.; Vicario, G.; Montini, T.; Barreca, D.; Balducci, G.; Fornasiero, P.; Tondello, E.; Graziani, M.

    2007-10-01

    TiO 2-based systems have attracted an increasing interest for their potential use as photocatalysts under visible-light irradiation. In this context, the present work was dedicated to the tailored synthesis of TiO 2 nanopowders doped with boron, nitrogen or both species for the photocatalytic degradation of organic dyes. In particular, the systems were synthesized by a sol-gel route starting from titanium(IV) butoxide as a Ti source and thoroughly characterized by the combined use of N 2 physisorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis reflectance spectroscopy and temperature-programmed oxidation (TPO). Finally, the photocatalytic performances in the decomposition of the azo-dye methyl orange (MO) were investigated. The obtained results suggest that both dopants promote the photocatalytic activity with respect to pure TiO 2 systems. Nevertheless, while our surface N-doping does not appreciably modify the titania structure and texture, B incorporation inhibits the TiO 2 crystallite growth and induces an increase in the surface area. As regards the codoped systems, a remarkable reactivity improvement was observed only when B is present in excess with respect to N. A rational interpretation of the observed behaviour was attempted by calculations based on the density functional theory (DFT). We suggest that the presence of B in molar excess with respect to N generates reactive Ti(III) sites, which, in turn, might induce the formation of reactive superoxide species.

  17. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation

    DOE PAGESBeta

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-09-10

    In this paper, a two-step process is developed to synthesize rare earth doped titania nanorods (RE–TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE–TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu–TiO2more » NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10-3 s-1. The La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. Finally, we further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.« less

  18. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products. PMID:26400095

  19. Improvement of (004) texturing by slow growth of Nd doped TiO2 films

    NASA Astrophysics Data System (ADS)

    Ali, A.; Yassitepe, E.; Ruzybayev, I.; Ismat Shah, S.; Bhatti, A. S.

    2012-12-01

    In this work, we present preferred (004) texturing of sputter deposited titanium dioxide (TiO2) films on glass substrates as a consequence of Nd doping at very slow growth rate. Nd concentration was varied from 0.0 to 2.0 atomic percent (at. %) in TiO2 thin films deposited under identical growth conditions, i.e., the growth rate of 0.6 Å/s and at 500 °C. At 2 at. % Nd, complete texturing along (004) plane was observed, as indicated by the X-ray diffraction analyses. Morphology of the deposited TiO2 films from pure to 2 at. % Nd doped TiO2 films showed faceted to planar growth. Visualization of electrical and structural analysis (VESTA) software revealed that the change in the morphology was due to preferential growth in (004) orientation. Raman spectroscopy highlighted the phonon confinement in the Eg mode, and a red shift was observed due to an increase in the anti-symmetry in bonding with increased Nd concentration. XPS results confirmed the variation in oxygen vacancy concentration along with the reduction of Ti and Nd valance states with the change in the dopant concentration. Our experiments confirmed that the substitution of Nd at Ti sites was responsible for texturing in (004) orientation and this was possible by growing films at a very slow rate.

  20. Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres with enhanced visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Jiang, Zhifeng; Wei, Wei; Mao, Danjun; Chen, Cheng; Shi, Yunfei; Lv, Xiaomeng; Xie, Jimin

    2014-12-01

    Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres (Ag-N-TiO2-YSM) were prepared by employing acetic acid as the hollowing controller and triethanolamine as the N source for the first time. Ag nanoparticles (NPs) were uniformly deposited by a simple in situ photo-reduction method, which can prevent the aggregation of Ag NPs. The efficiency of the as-prepared samples was investigated by monitoring the degradation of rhodamine B and ciprofloxacin under visible light irradiation. The experimental results indicate that N-doped yolk-shell mesoporous TiO2 hollow microspheres show higher photocatalytic activity than P25 TiO2 under visible light irradiation because of N doping and the unique yolk-shell structure. In addition, Ag-N-TiO2-YSM shows enhanced activity compared with N-TiO2-YSM due to the SPR absorption of silver NPs and the fast generation, separation and transportation of the photogenerated carriers. Moreover, the Ag contents can affect the photocatalytic activity of the Ag-N-TiO2-YSM composite. A suitable amount of Ag deposition gives the highest photocatalytic activity. A higher loading does not improve the photocatalytic activity of N-TiO2-YSM further. The active species generated in the photocatalytic system were also investigated. Based on our experimental results, a possible photocatalytic mechanism was proposed. The strategy presented here gives a promising route towards the development of delicate metal@hollow semiconductor composites for many applications in photocatalysis.Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres (Ag-N-TiO2-YSM) were prepared by employing acetic acid as the hollowing controller and triethanolamine as the N source for the first time. Ag nanoparticles (NPs) were uniformly deposited by a simple in situ photo-reduction method, which can prevent the aggregation of Ag NPs. The efficiency of the as-prepared samples was investigated by monitoring the degradation of rhodamine B and

  1. Effect of doping level of colored TiO2 nanotube arrays fabricated by electrochemical self-doping on electrochemical properties.

    PubMed

    Kim, Choonsoo; Kim, Seonghwan; Hong, Sung Pil; Lee, Jaehan; Yoon, Jeyong

    2016-06-01

    Recently, two types of TiO2 nanotube arrays (NTAs) (blue- and black-colored TiO2 NTAs), which are easily fabricated by electrochemical self-doping, have gained much attention due particularly to their enhanced capacitive and oxidant-generating properties. These enhanced electrochemical properties mean that they have potential as basic materials for energy and environmental applications, such as in supercapacitors and anodes for water treatment. However, the understanding of the effect of the doping level of these TiO2 NTAs on their electrochemical properties is limited because there is no direct comparison or relevant discussion of their respective electrochemical properties under the same conditions, despite the similar surface characteristics of the TiO2 NTAs obtained by comparable electrochemical doping. Therefore, the objective of this study was to investigate the effect of the doping level of blue and black TiO2 NTAs on their electrochemical properties, including the capacitive and oxidant-generating properties. Although no significant difference in their surface properties was found using SEM, XRD and XPS, the black TiO2 NTA revealed a slightly higher doping level than the blue TiO2 NTA, which is caused by the order of the electrochemical self-doping and annealing conditions. With the different doping levels of the two TiO2 NTAs, the black TiO2 NTA showed a higher areal capacitance, indicating good capacitive properties, and better service life in oxidant-generation than that of the blue TiO2 NTA. The blue TiO2 NTA exhibited a larger oxygen evolution overpotential and higher chlorine evolution efficiency than that of the black TiO2 NTA. We report that the new knowledge on blue and black TiO2 NTAs from this study can contribute to the further development of supercapacitors and oxidant-generating anodes for water treatment. PMID:27169417

  2. Photonic, and photocatalytic behavior of TiO2 mediated by Fe, CO, Ni, N doping and co-doping

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Zhao, Y. F.; Wang, T.; Li, H.; Li, C.

    2015-12-01

    Fe, Co, Ni, or N addition could modulate the photonic and catalytic responses of TiO2 for photocatalysts applications. Their morphologies, structures, compositions and photocatalytic performance in the degradation of methylene blue were characterized by scanning electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy, Raman spectra and X-ray photoelectron spectroscopy. The results showed that dopants affect the electronic transition energies by changing the optical band gap and the impurity absorption peaks of the specimens. Especially, co-doping enhances the visible-light photocatalytic activity of TiO2 by 4-10 times that of pure TiO2, and the Co and N co-doping derives 10-fold photocatalytic activity.

  3. Chemical assembly of TiO2 and TiO2@Ag nanoparticles on silk fiber to produce multifunctional fabrics.

    PubMed

    Li, Guohong; Liu, Hong; Zhao, Hongshi; Gao, Yuqiang; Wang, Jiyang; Jiang, Huaidong; Boughton, R I

    2011-06-01

    A carefully designed surface modification technique for the manufacture of multifunctional silk textile nanocomposite materials is successfully developed by the functionalization of silk with TiO(2) and TiO(2)@Ag nanoparticles (NPs). The NPs are assembled onto a silk substrate through covalent linkages, including enediol ligand-metal oxide bonding, resin dehydration and the acylation of silk. Owing to the strong chemical bonding, silk fibroin fabric (SFF) and the NPs form a stable composite system. The functionalized SFF, especially TiO(2)@Ag NP-functionalized SFF are endowed with remarkable UV protection properties, and an efficient anti-bacterial capability toward Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Furthermore, the nearly total photodegradation of methylene orange (MO) under UV illumination illustrates that functionalized SFF possesses high photocatalytic and self-cleaning capability. This multifunctional silk material satisfies the market demand for natural "smart" products, and is a promising practical material for use in the textile industry, hospital sterilization and environmental cleanup. PMID:21419419

  4. 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

  5. Influence of rhodamine 6G doping on the optical properties of TiO2 sol-gel films

    NASA Astrophysics Data System (ADS)

    Tomás, S. A.; Stolik, S.; Palomino, R.; Lozada, R.; Persson, C.; Pepe, I.; da Silva, A. Ferreira

    2005-10-01

    Amorphous titanium dioxide (TiO2) thin films doped with rhodamine 6G (R6G) were deposited on glass substrates by the sol-gel process. The optical properties of the films were characterized by photoacoustic, excitation, and fluorescence spectroscopies. The absorption spectra of the R6G-doped TiO2 films exhibited two well-defined absorption regions: an absorption band over 2.0 eV attributed to rhodamine 6G and a band above 3.0 eV corresponding to TiO2 absorption. While the onset of the R6G absorption band was shifted by 0.06 eV towards lower energies as the R6G doping concentration increased within the interval of 0.01-0.10 mol %, the onset to high absorption (TiO2 band) for the doped films decreased only by 0.01 eV within the same interval. In addition, the optical absorption of undoped rutile-phase bulk TiO2 was calculated and compared to the experimental results. The estimated theoretical value of rutile TiO2 sample was 3.0 eV. This theoretical result shows good agreement when compared with the experimental data of undoped TiO2 sol-gel films, as well as the undoped TiO2 film prepared by sputtering.

  6. Plasma induced tungsten doping of TiO2 particles for enhancement of photocatalysis under visible light.

    PubMed

    Ishida, Yohei; Motokane, Yasutomo; Tokunaga, Tomoharu; Yonezawa, Tetsu

    2015-10-14

    Here we report a novel method for modifying commercially available TiO2 nanoparticles by a microwave-induced plasma technique. After the plasma treatment TiO2 nanoparticles showed enhanced visible absorption due to the doped W atoms, and the photocatalytic methylene blue degradation above 440 nm was successfully improved. PMID:26344653

  7. Photoelectrochemical oxidation of ibuprofen via Cu2O-doped TiO2 nanotube arrays.

    PubMed

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-12-01

    A p-n junction based Cu2O-doped TiO2 nanotube arrays (Cu2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu2O-TNAs was greatly reduced. SEM images revealed that the supported TiO2 nanotubes had diameters of approximately 80nm and lengths of about 2.63μm. Upon doping with Cu2O, the TiO2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τel, of TNAs and Cu2O/TNAs were 6.91 and 26.26ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured. PMID:27021261

  8. Flame-made Nb-doped TiO2 ethanol and acetone sensors.

    PubMed

    Phanichphant, Sukon; Liewhiran, Chaikarn; Wetchakun, Khatcharin; Wisitsoraat, Anurat; Tuantranont, Adisorn

    2011-01-01

    Undoped TiO(2) and TiO(2) nanoparticles doped with 1-5 at.% Nb were successfully produced in a single step by flame spray pyrolysis (FSP). The phase and crystallite size were analyzed by XRD. The BET surface area (SSA(BET)) of the nanoparticles was measured by nitrogen adsorption. The trend of SSA(BET) on the doping samples increased and the BET equivalent particle diameter (d(BET)) (rutile) increased with the higher Nb-doping concentrations while d(BET) (anatase) remained the same. The morphology and accurate size of the primary particles were further investigated by high-resolution transmission electron microscopy (HRTEM). The crystallite sizes of undoped and Nb-doped TiO(2) spherical were in the range of 10-20 nm. The sensing films were prepared by spin coating technique. The mixing sample was spin-coated onto the Al(2)O(3) substrates interdigitated with Au electrodes. The gas sensing of acetone (25-400 ppm) was studied at operating temperatures ranging from 300-400 °C in dry air, while the gas sensing of ethanol (50-1,000 ppm) was studied at operating temperatures ranging from 250-400 °C in dry air. PMID:22346586

  9. Ni-doped TiO2 nanotubes for wide-range hydrogen sensing

    PubMed Central

    2014-01-01

    Doping of titania nanotubes is one of the efficient way to obtain improved physical and chemical properties. Through electrochemical anodization and annealing treatment, Ni-doped TiO2 nanotube arrays were fabricated and their hydrogen sensing performance was investigated. The nanotube sensor demonstrated a good sensitivity for wide-range detection of both dilute and high-concentration hydrogen atmospheres ranging from 50 ppm to 2% H2. A temperature-dependent sensing from 25°C to 200°C was also found. Based on the experimental measurements and first-principles calculations, the electronic structure and hydrogen sensing properties of the Ni-doped TiO2 with an anatase structure were also investigated. It reveals that Ni substitution of the Ti sites could induce significant inversion of the conductivity type and effective reduction of the bandgap of anatase oxide. The calculations also reveal that the resistance change for Ni-doped anatase TiO2 with/without hydrogen absorption was closely related to the bandgap especially the Ni-induced impurity level. PMID:24624981

  10. Flame-Made Nb-Doped TiO2 Ethanol and Acetone Sensors

    PubMed Central

    Phanichphant, Sukon; Liewhiran, Chaikarn; Wetchakun, Khatcharin; Wisitsoraat, Anurat; Tuantranont, Adisorn

    2011-01-01

    Undoped TiO2 and TiO2 nanoparticles doped with 1–5 at.% Nb were successfully produced in a single step by flame spray pyrolysis (FSP). The phase and crystallite size were analyzed by XRD. The BET surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption. The trend of SSABET on the doping samples increased and the BET equivalent particle diameter (dBET) (rutile) increased with the higher Nb-doping concentrations while dBET (anatase) remained the same. The morphology and accurate size of the primary particles were further investigated by high-resolution transmission electron microscopy (HRTEM). The crystallite sizes of undoped and Nb-doped TiO2 spherical were in the range of 10–20 nm. The sensing films were prepared by spin coating technique. The mixing sample was spin-coated onto the Al2O3 substrates interdigitated with Au electrodes. The gas sensing of acetone (25–400 ppm) was studied at operating temperatures ranging from 300–400 °C in dry air, while the gas sensing of ethanol (50–1,000 ppm) was studied at operating temperatures ranging from 250–400 °C in dry air. PMID:22346586

  11. Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

  12. Understanding the dispersion of Ag on high surface area TiO2 supports using XPS intensity ratios

    NASA Astrophysics Data System (ADS)

    Davis, Zenda D.; Tatarchuk, Bruce J.

    2015-10-01

    Silver-titania (Ag/TiO2) adsorbents, in the range of 4 wt% Ag, display high selectivity toward sulfur heterocyclic compounds from complex fuel streams containing other aromatics. An experimental investigation of Ag on TiO2 has been undertaken to understand the state of dispersion and growth of Ag. XPS is one of the more promising characterization tools for the state of dispersion. Silver loading from 1 wt% to 20 wt% on 150 m2/g titania was investigated. Ag/Ti intensity ratios increased linearly with Ag content up to 4 wt% and increased less significantly thereafter from 8 wt% to 20 wt% indicating nucleation and growth of Ag crystallites. Inelastic mean free path (IMFP) calculations were used to estimate Ag crystallite size based on the attenuation of the Ag signal, realizing in this regime there is insufficient Ag to attenuate background titania. At 4, 8, 12, and 20 wt% the estimated average crystallite sizes were 0.35, 0.71, 0.84, and 1.11 nm respectively. Ag loadings up to 4 wt% were present in the form of Ag+1 adatoms presumably occupying TiO2 surface defects. Saturation of surface TiO2 defects is in good agreement with quantitative sulfur heterocycle adsorption.

  13. Effects of TiO2 and Ag nanoparticles on polyhydroxybutyrate biosynthesis by activated sludge bacteria.

    PubMed

    Priester, John H; Van De Werfhorst, Laurie C; Ge, Yuan; Adeleye, Adeyemi S; Tomar, Shivira; Tom, Lauren M; Piceno, Yvette M; Andersen, Gary L; Holden, Patricia A

    2014-12-16

    Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L(-1)). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers. PMID:25409530

  14. First principles study of oxygen vacancies in (Mo + C)-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Cui, Jie; Liang, Shuhua; Wang, Xianhui; Zhang, Jianmin

    2015-05-01

    The structural and electronic properties of neutral oxygen vacancies in (Mo + C)-doped anatase TiO2 were investigated using frozen-core projector-augmented wave (PAW) method within GGA +U approximation. Six possible oxygen vacancy sites were considered in the present work. The results show that the octahedral vertex adjacent to Mo and opposite from C is the most stable position for oxygen vacancy based on the results of the formation energy. The Fermi level is located at above the bottom of the conduction band and a typical n-type metallic behavior occurs as a result of the oxygen vacancy appeared in (Mo + C) doped TiO2.

  15. Low temperature resistivity, thermoelectricity, and power factor of Nb doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Jaćimović, J.; Gaál, R.; Magrez, A.; Piatek, J.; Forró, L.; Nakao, S.; Hirose, Y.; Hasegawa, T.

    2013-01-01

    The resistivity of a very high quality anatase TiO2 doped with 6% of Nb was measured from 300 K down to 40 mK. No sign of superconductivity was detected. Instead, a minute quantity of cation vacancies resulted in a Kondo scattering. Measurements of thermo-electric power and resistivity were extended up to 600 K. The calculated power factor has a peak value of 14 μW/(K2cm) at 350 K, which is comparable to that of Bi2Te3 [Venkatasubramanian et al., Nature 413, 597 (2001)], the archetype thermolectrics. Taking the literature value for the thermal conductivity of Nb doped TiO2 thin films, the calculated figure of merit (ZT) is in the range of 0.1 above 300 K. This value is encouraging for further engineering of the material in order to reach ZT of 1 suitable for high temperature thermoelectrics.

  16. Experimental study of transition metal ion doping on TiO2 with photocatalytic behavior.

    PubMed

    Siddhapara, K S; Shah, D V

    2014-08-01

    In this research, we have studied the doping behaviors of three transition metal ion dopants on the crystal phase, particle sizes, XRD patterns, EDAX spectra, and photoreactivity of TiO2 nanoparticles. Test metal ion concentrations ranged from 1% to 4 at.%, we report the growth of [Fe, Co and Mn]xTiO2 nanocrystals prepared by Sol-Gel technique, followed by freeze-drying treatment at -30 °C temperature for 12 hrs. The obtained Gel was thermally treated at different temperature like 200 °C, 400 °C, 600 °C, 800 °C. Thermal gravimetric analysis (TGA) shows that dopant concentration affects thermal decomposition. The photoreactivities of transition metal ion-doped TiO2 nanoparticles under UV irradiation were quantified by the degradation of formaldehyde. PMID:25936115

  17. 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.

  18. Sequential laser and ultrasonic wave generation of TiO2@Ag core-shell nanoparticles and their anti-bacterial properties.

    PubMed

    Hamad, Abubaker Hassan; Li, Lin; Liu, Zhu; Zhong, Xiang Li; Wang, Tao

    2016-02-01

    Core-shell nanoparticles have unusual physical, chemical and biological properties. Until now, for the Ag and TiO2 combination, only Ag core and TiO2 shell nanoparticles have been practically demonstrated. In this investigation, novel TiO2@Ag core-shell (TiO2 core and Ag shell) nanoparticles were produced via ultrasonic vibration of Ag-TiO2 compound nanoparticles. A bulk Ti/Ag alloy plate was used to generate colloidal Ag-TiO2 compound nanoparticles via picosecond laser ablation in deionised water. The colloidal nanoparticles were then sonicated in an ultrasonic bath to generate TiO2@Ag core-shell nanoparticles. They were characterised using a UV-VIS spectrometer, transmission electron microscopy (TEM), high-angle annular dark-field-Scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The Ag-TiO2 compound and the TiO2@Ag core-shell nanoparticles were examined for their antibacterial activity against Escherichia coli (E. coli) JM109 strain bacteria and compared with those of Ag and TiO2 nanoparticles. The antibacterial activity of the core-shell nanoparticles was slightly better than that of the compound nanoparticles at the same concentration under standard laboratory light conditions and both were better than the TiO2 nanoparticles but not as good as the Ag nanoparticles. PMID:26714980

  19. Towards TiO2sbnd Ag porous nanocomposites based SERS sensors for chemical pollutant detection

    NASA Astrophysics Data System (ADS)

    Iancu, Vlad; Baia, Lucian; Tarcea, Nicolae; Popp, Jürgen; Baia, Monica

    2014-09-01

    Since the TiO2 environmental friendly character and the affinity of a large variety of molecules to bind to the silver surfaces are well-known, novel porous nanoarchitectures based on TiO2 aerogel and Ag colloidal particles deposited on a poly(methyl methacrylate) (PMMA) substrate were obtained. The ability of the deposited porous structures to detect by surface-enhanced Raman spectroscopy (SERS) contaminant species adsorbed from aqueous media was tested. The morphological particularities of the bulk samples during the deposition on the PMMA substrates were preserved. The SERS detection efficiency was assessed by using congo red as a test molecule. No matter the average size of the Ag nanoparticles, the lowest detectable concentrations were found be of around 5 × 10-6 M for all samples. The morphological parameters such as median pore diameter and cumulative pore volume were also taken into consideration when discussing the detection performances. Moreover, calibration curves have been obtained in order to estimate an unknown concentration of the analyte. The obtained results show the real potential of the prepared porous composites for further use in the development of new SERS-based sensors for monitoring of water quality, especially when the contaminants are dye molecules.

  20. Narrow-linewidth red-emission Eu3+-doped TiO2 spheres for light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Zhu, Peifen; Zhu, Hongyang; Qin, Weiping; Dantas, Breno H.; Sun, Wei; Tan, Chee-Keong; Tansu, Nelson

    2016-03-01

    In this work, the amorphous Eu3+-doped TiO2 spheres were synthesized by low cost mixed-solvent method, while the anatase and rutile spheres can be obtained by annealing the as-synthesized amorphous TiO2 spheres at elevated temperatures. The optical properties of Eu3+-doped TiO2 spheres were also investigated, and strong red emission (centered at 610 nm) with narrow line-width of 30 nm was observed under 465 nm or 394 nm excitations for the Eu3+-doped anatase TiO2 spheres. Our findings indicate the potential of using Eu3+-doped TiO2 spheres to achieve red emission with InGaN blue light emitting diodes (LEDs). Owing to the high light extraction efficiency in the GaN-based LEDs using anatase TiO2 spheres as demonstrated in our previous works, this work shows the strong potential of Eu3+-doped TiO2 spheres as the red phosphor material for high efficiency GaN-based white light-emitting diode.

  1. Contributions of Ag Nanowires to the Photoelectric Conversion Efficiency Enhancement of TiO2 Dye-Sensitized Solar Cells.

    PubMed

    Liu, Yunyu; She, Guangwei; Qi, Xiaopeng; Mu, Lixuan; Wang, Xuesong; Shi, Wensheng

    2015-09-01

    Ag nanowires (AgNWs) were employed in mesoporous TiO2 dye-sensitized solar cells (DSSCs) to enhance the photoelectric conversion efficiency (PCE). The possible reasons for PCE improvement, i.e., improvement in electron transport and light harvesting due to light scattering and plasmonic resonance effect of AgNWs are investigated. Electrochemical impedance spectra (EIS) study proved that addition of AgNWs can enhance the conductivity of TiO2 thin film photoanode, which is an important reason for the increase of photocurrent. Furthermore, through the comparison experiments as well as the UV-Vis absorption and IPCE characterization, contributions of the light scattering and plasmonic resonance effect to the enhancement of light harvest, and thus PCE of the DSSCs were demonstrated. It was found that fast electron transport of AgNWs played more important role for the PCE improvement than the light harvest enhancement due to light scattering and plasmonic effect. Based on these investigations, the AgNWs modified TiO2 thin film DSSCs were optimized. After integrating AgNWs into the photoanode, the photocurrent increased significantly and PCE increased -50% comparing with the pure TiO2-based DSSCs. PMID:26716285

  2. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-05-01

    TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

  3. C-doped mesoporous anatase TiO2 comprising 10nm crystallites.

    PubMed

    Xie, Chong; Yang, Shenghui; Li, Beibei; Wang, Hongkong; Shi, Jian-Wen; Li, Guodong; Niu, Chunming

    2016-08-15

    We report a C-doped mesoporous anatase TiO2 with high surface area synthesized using multi-walled carbon nanotube (MWCNT) mat as a "rigid" template and carbon doping source. The characterization by SEM, HRTEM, X-ray diffraction and nitrogen adsorption revealed that TiO2 samples have a porous structure which are figuratively a inverse copy of MWCNT network and pore walls are formed by interconnected TiO2 nanoparticles with average diameter of ∼10nm. We found that annealing temperatures from 400 to 1000°C before MWCNT template removal had very limited effect on particle size (∼10nm), surface area (112-129m(2)/g) and total pore volume (0.74-0.85m(2)/g) of the samples through a significantly delayed phase transition from anatase to rutile started at 800°C, resulting in only ∼9.1% conversion at 1000°C. The pore size distribution is in mesopore range from 6 to 60nm peaked at ∼24nm. XPS analysis showed a relatively strong C1s peak at 288.4eV, indicating C doping at Ti sites, which is responsible for red shift of adsorption edge of UV-vis spectra and photocatalytic activity in visible-light region. PMID:27179173

  4. Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Tao, Junguang; Pan, H.; Wong, Lai Mun; Wong, Ten It; Chai, J. W.; Pan, Jisheng; Wang, S. J.

    2014-03-01

    Heavily Nb-doped anatase TiO2 (TNO) thin films were prepared by pulsed dc magnetron sputtering using an Nb-doped TiO2 target. The as-grown films exhibit high resistivity whose resistance decreases by ˜2 × 104-fold upon vacuum annealing. The ˜40% Nb-doped anatase TiO2 film shows a low resistivity of 5.7 × 10-4 Ω cm and a high electron concentration of 3.07 × 1021 cm-3. Combined in situ x-ray photoelectron spectroscopy (XPS) measurement and density-functional theory (DFT) calculations show that oxygen interstitial (Oint) and Nb interstitial (Nbint) defect clusters introduce localized shallow p-type accepter states that trap the electrons and reduce the conductivity. These defect clusters can be eliminated by vacuum annealing which is companied by outward diffusion of Nb. As a result, the trapped electrons backfill the Ti sites which are delocalized to promote conductivity.

  5. Huge low-frequency dielectric response of (Nb,In)-doped TiO2 ceramics

    NASA Astrophysics Data System (ADS)

    Wu, Y. Q.; Zhao, X.; Zhang, J. L.; Su, W. B.; Liu, J.

    2015-12-01

    The (Nb,In)-doped TiO2 ceramics have drawn considerable attention as a type of promising giant-permittivity dielectric materials in recent years. However, a significant controversy concerning the giant dielectric mechanism currently exists, and clarifying it is vitally important from both scientific and technological viewpoints. This letter reports the results of a systematical comparison study, where two kinds of (Nb,In)-doped TiO2 ceramics with a substantial difference in dielectric loss are used. Dielectric properties and complex impedance are investigated over a broad frequency band of 3 mHz-110 MHz. A huge low-frequency dielectric response in addition to the giant dielectric relaxation appearing above 1 MHz is observed for both kinds of (Nb,In)-doped TiO2 ceramics in dielectric dispersion. The huge dielectric response observed in the low frequency range can be ascribed to a non-ohmic electrode-contact, and the dielectric relaxation appearing above 1 MHz can be attributed to an internal barrier layer capacitance effect. An electrical equivalent circuit model suggested can well describe the observed dielectric properties and electrical behaviors.

  6. Photocatalytic activity of multielement doped TiO 2 in the degradation of congo red

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, R.; Kalaivani, S.; Amala Infant Joice, J.; Sivakumar, T.

    2012-01-01

    TiO2 although considered a promising photocatalyst for the degradation of aqueous pollutants, it suffers from poor absorption in the visible region and hence requires ultraviolet (UV) light for activation. To make TiO2 a visible active photocatalyst, multielement (C, N, B, and F) doping has been done. The synthesised CNBF/TiO2 catalysts were calcined at different temperatures and characterized by XRD, BET surface area, UV DRS, XPS, HRSEM-EDAX, and TEM techniques. These catalysts found to show less band gap values when compared to bare TiO2. These catalysts were tested for their catalytic activity towards the degradation of a textile dye - congo red (CR) under different reaction conditions. It was found that the photocatalytic activity was dependent on both doping of multielement and the calcination temperature of CNBF/TiO2. The co-doped catalysts which were calcined at 400 °C and 600 °C (100% intensity in anatase phase) were found to be the best catalysts (100% decolourisation of CR in 21/2 h and 2 h respectively). TOC analysis carried out for the samples at the reaction time of 5 h showed very high percentage (83%) degradation of CR over CNBF/TiO2 catalysts calcined at 600 °C when compared to the other catalysts calcined at different temperatures. CNBF/TiO2 (1000 °C) showed very less photocatalytic activity due to the formation of rutile phase.

  7. Effects of charging and doping on orbital hybridizations and distributions in TiO2 clusters

    NASA Astrophysics Data System (ADS)

    Zhao, Hong Min; Wu, Miao Miao; Wang, Qian; Jena, Puru

    2011-11-01

    Charging and doping are two important strategies used in TiO2 quantum dots for photocatalysis and photovoltaics. Using small clusters as the prototypes for quantum dots, we have carried out density functional calculations to study the size-specific effects of charging and doping on geometry, electronic structure, frontier orbital distribution, and orbital hybridization. We find that in neutral (TiO2)n clusters the charge transfer from Ti to O is almost size independent, while for the anionic (TiO2)n clusters the corresponding charge transfer is reduced but it increases with size. When one O atom is substituted with N, the charge transfer is also reduced due to the smaller electron affinity of N. As the cluster size increases, the populations of 3d and 4s orbitals of Ti decrease with size, while the populations of the 4p orbital increase, suggesting size dependence of spd hybridizations. The present study clearly shows that charging and doping are effective ways for tailoring the energy gap, orbital distributions, and hybridizations.

  8. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    NASA Astrophysics Data System (ADS)

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  9. Boron-Doped Anatase TiO2 as a High-Performance Anode Material for Sodium-Ion Batteries.

    PubMed

    Wang, Baofeng; Zhao, Fei; Du, Guodong; Porter, Spencer; Liu, Yong; Zhang, Peng; Cheng, Zhenxiang; Liu, Hua Kun; Huang, Zhenguo

    2016-06-29

    Pristine and boron-doped anatase TiO2 were prepared via a facile sol-gel method and the hydrothermal method for application as anode materials in sodium-ion batteries (SIBs). The sol-gel method leads to agglomerated TiO2, whereas the hydrothermal method is conducive to the formation of highly crystalline and discrete nanoparticles. The structure, morphology, and electrochemical properties were studied. The crystal size of TiO2 with boron doping is smaller than that of the nondoped crystals, which indicates that the addition of boron can inhibit the crystal growth. The electrochemical measurements demonstrated that the reversible capacity of the B-doped TiO2 is higher than that for the pristine sample. B-doping also effectively enhances the rate performance. The capacity of the B-doped TiO2 could reach 150 mAh/g at the high current rate of 2C and the capacity decay is only about 8 mAh/g over 400 cycles. The remarkable performance could be attributed to the lattice expansion resulting from B doping and the shortened Li(+) diffusion distance due to the nanosize. These results indicate that B-doped TiO2 can be a good candidate for SIBs. PMID:27258029

  10. 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.

  11. Wide-range hydrogen sensing with Nb-doped TiO2 nanotubes.

    PubMed

    Liu, Hegang; Ding, Dongyan; Ning, Congqin; Li, Zhaohui

    2012-01-13

    Anatase-type titania nanotubes doped with Nb element were fabricated through an anodization of Ti35Nb alloy substrate and further annealing at 450 °C. Hydrogen sensitivity of the Nb-doped TiO(2) nanotubes at room temperature was investigated through exposure of the nanotube samples to different hydrogen atmospheres. At room temperature, the Nb-doped nanotubes demonstrated a good sensitivity for wide-range detection of both dilute and high-concentration hydrogen atmospheres ranging from 50 ppm to 2% H(2). The Nb-doped nanotubes also presented remarkable reversibility and repeatability as well as a quick response to the hydrogen atmosphere. The Nb-doped titania nanotubes have great advantages as robust and wide-range hydrogen sensors operating at room temperature. PMID:22156054

  12. The effects of n-type doping on lithium storage in TiO2.

    PubMed

    Shin, Ji-Yong; Joo, Jong Hoon; Adepalli, Kiran K; Samuelis, Dominik; Maier, Joachim

    2016-04-01

    In this report, we discuss the Li-storage performance of niobium-doped TiO2 nanostructures (Ti(1-y)Nb(y)O(2+δ)), with a special focus on the effects of ionic/electronic charge carrier concentration (defect chemistry) on Li storage and transport properties. By Nb-doping, Li storage kinetics of titania electrode material is significantly improved mainly due to the increased electronic charge carrier concentration (n-type doping). However, it was found that there is a maximum beyond which further doping is rather detrimental to Li diffusion kinetics. Defect chemical analysis indicates that this limited doping effect is due to the trapping of free lithium ions by the critical electron-ion association reactions at room temperature such as Li(i)(•) + e' ⇌ Li(i)(×) and Nb(Ti)(•) + e' ⇌ Nb(Ti)(×). PMID:26961152

  13. Nb doping of TiO2 nanotubes for an enhanced efficiency of dye-sensitized solar cells.

    PubMed

    Yang, Min; Kim, Doohun; Jha, Himendra; Lee, Kiyoung; Paul, Jonathan; Schmuki, Patrik

    2011-02-21

    Nb-doped TiO(2) nanotube (with C(Nb) < 1 wt%) layers were successfully fabricated by self-ordered electrochemical anodization of Ti-Nb alloys. When used in dye-sensitized solar cells the efficiency enhanced by up to 30% compared to non-doped TiO(2) nanotubes. IMVS measurements indicate the beneficial effect to be due to lower recombination losses. PMID:21184009

  14. Fabrication and characterization of perovskite-type solar cells with Nb-doped TiO2 layers

    NASA Astrophysics Data System (ADS)

    Saito, Jo; Oku, Takeo; Suzuki, Atsushi; Akiyama, Tsuyoshi

    2016-02-01

    Organic-inorganic hybrid heterojunction solar cells containing perovskite CH3NH3PbI3 using Nb-doped TiO2 as an electron-transporting layer were fabricated and characterized. Nb-doped TiO2 layer showed an improvement of the short-circuit current density and power conversion efficiency using Ti0.95Nb0.05O2.

  15. Origin of leakage paths driven by electric fields in Al-doped TiO2 films.

    PubMed

    Park, Gyeong-Su; Park, Seong Yong; Heo, Sung; Kwon, Ohseong; Cho, Kyuho; Han, Kwan-Young; Kang, Sung Jin; Yoon, Aram; Kim, Miyoung

    2014-12-23

    The growth of leakage current paths in Al-doped TiO2 (ATO) films is observed by in situ TEM under negative bias stress. Through systematic HAADF-STEM, STEM-EDS, and STEM-EELS studies, it is confirmed that the electric field-induced growth of the Ru-doped TiO2 phase is the main reason for the ATO film's negative leakage. PMID:25366700

  16. Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films.

    PubMed

    Cordova, Isvar A; Peng, Qing; Ferrall, Isa L; Rieth, Adam J; Hoertz, Paul G; Glass, Jeffrey T

    2015-05-14

    TiO2 is an exemplary semiconductor anode material for photoelectrochemical (PEC) water-splitting electrodes due to its functionality, long-term stability in corrosive environments, nontoxicity, and low cost. In this study, TiO2 photoanodes with enhanced photocurrent density were synthesized by atomic layer deposition (ALD) of TiO2 onto a porous, transparent, and conductive fluorine-doped tin oxide nanoparticle (nanoFTO) scaffold fabricated by solution processing. The simplicity and disordered nature of the nanoFTO nanostructure combined with the ultrathin conformal ALD TiO2 coatings offers advantages including decoupling charge carrier diffusion length from optical penetration depth, increased photon absorption probability through scattering, complimentary photon absorption, and favorable interfaces for charge separation and transfer across the various junctions. We examine the effects of porosity of the nanoFTO scaffold and thickness of the TiO2 coating on PEC performance and achieve an optimal photocurrent of 0.7 mA cm(-2) at 0 V vs. Ag/AgCl under 100 mW cm(-2) AM 1.5 G irradiation in a 1 M KOH aqueous electrolyte. Furthermore, the fundamental mechanisms behind the improvements are characterized via cyclic voltammetry, incident photon-to-current efficiency, transient photocurrent spectroscopy, and electrochemical impedance spectroscopy and are contrasted with those of single crystal rutile TiO2 nanowires. The strategies employed in this work highlight the opportunities inherent to these types of heteronanostructures, where the lessons may be applied to improve the PEC conversion efficiencies of other promising semiconductors, such as hematite (α-Fe2O3) and other materials more sensitive to visible light. PMID:25899449

  17. Electrical Conductivity, Thermoelectric Power, and Equilibration Kinetics of Nb-Doped TiO2.

    PubMed

    Nowotny, Janusz; Bak, Tadeusz; Dickey, Elisabeth C; Sigmund, Wolfgang; Alim, Mohammad A

    2016-09-01

    This work considers the equilibration kinetics of Nb-doped TiO2 single crystal (0.066 atom % Nb) during oxidation and reduction within a wide range of temperature (1073-1298 K) and oxygen activity (10(-14)-10(5) Pa). The associated semiconducting properties were determined using simultaneous measurements of both electrical conductivity and thermoelectric power. It is shown that the chemical diffusion coefficient in the strongly reducing regime, p(O2) < 10(-5) Pa, is 4 orders of magnitude larger than that in the reducing and oxidizing regimes, 10 Pa < p(O2) < 22 kPa. The derived theoretical model considers the gas/solid kinetics for the TiO2/O2 system in terms of two diffusion regimes: the fast regime related to fast defects (oxygen vacancies and titanium interstitials) and leading to quasi-equilibrium, and the slow regime associated with slow defects (titanium vacancies) resulting in the gas/solid equilibrium. It has been shown that incorporation of donor-type elements, such as niobium, and imposition of oxygen activity above a certain critical value, results in a substantial reduction in the concentration of high mobility defects and leads to slowing down the equilibration kinetics. In consequence, the fast kinetic regime is not observed. Comparison of the kinetic data for Nb-doped TiO2 single crystal (this work) and polycrystalline Nb-doped TiO2 (reported before) indicates that the gas/solid kinetics for the polycrystalline specimen at higher oxygen activities is rate controlled by the transport of oxygen within individual grains. PMID:27490974

  18. Preparation and use of photocatalytically active segmented Ag|ZnO and coaxial TiO2-Ag nanowires made by templated electrodeposition.

    PubMed

    Maijenburg, A Wouter; Rodijk, Eddy J B; Maas, Michiel G; Ten Elshof, Johan E

    2014-01-01

    Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 µm were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution. PMID:24837535

  19. Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

    PubMed Central

    Maijenburg, A. Wouter; Rodijk, Eddy J.B.; Maas, Michiel G.; ten Elshof, Johan E.

    2014-01-01

    Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 µm were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution. PMID:24837535

  20. Effect on Electron Structure and Magneto-Optic Property of Heavy W-Doped Anatase TiO2.

    PubMed

    Hou, Qingyu; Zhao, Chunwang; Guo, Shaoqiang; Mao, Fei; Zhang, Yue

    2015-01-01

    The spin or nonspin state of electrons in W-doped anatase TiO2 is very difficult to judge experimentally because of characterization method limitations. Hence, the effect on the microscopic mechanism underlying the visible-light effect of W-doped anatase TiO2 through the consideration of electronic spin or no-spin states is still unknown. To solve this problem, we establish supercell models of W-doped anatase TiO2 at different concentrations, followed by geometry optimization and energy calculation based on the first-principle planewave norm conserving pseudo-potential method of the density functional theory. Calculation results showed that under the condition of nonspin the doping concentration of W becomes heavier, the formation energy becomes greater, and doping becomes more difficult. Meanwhile, the total energy increases, the covalent weakens and ionic bonds strengthens, the stability of the W-doped anatase TiO2 decreases, the band gap increases, and the blue-shift becomes more significant with the increase of W doping concentration. However, under the condition of spin, after the band gap correction by the GGA+U method, it is found that the semimetal diluted magnetic semiconductors can be formed by heavy W-doped anatase TiO2. Especially, a conduction electron polarizability of as high as near 100% has been found for the first time in high concentration W-doped anatase TiO2. It will be able to be a promising new type of dilute magnetic semiconductor. And the heavy W-doped anatase TiO2 make the band gap becomes narrower and absorption spectrum red-shift. PMID:25955308

  1. Effect on Electron Structure and Magneto-Optic Property of Heavy W-Doped Anatase TiO2

    PubMed Central

    Hou, Qingyu; Zhao, Chunwang; Guo, Shaoqiang; Mao, Fei; Zhang, Yue

    2015-01-01

    The spin or nonspin state of electrons in W-doped anatase TiO2 is very difficult to judge experimentally because of characterization method limitations. Hence, the effect on the microscopic mechanism underlying the visible-light effect of W-doped anatase TiO2 through the consideration of electronic spin or no-spin states is still unknown. To solve this problem, we establish supercell models of W-doped anatase TiO2 at different concentrations, followed by geometry optimization and energy calculation based on the first-principle planewave norm conserving pseudo-potential method of the density functional theory. Calculation results showed that under the condition of nonspin the doping concentration of W becomes heavier, the formation energy becomes greater, and doping becomes more difficult. Meanwhile, the total energy increases, the covalent weakens and ionic bonds strengthens, the stability of the W-doped anatase TiO2 decreases, the band gap increases, and the blue-shift becomes more significant with the increase of W doping concentration. However, under the condition of spin, after the band gap correction by the GGA+U method, it is found that the semimetal diluted magnetic semiconductors can be formed by heavy W-doped anatase TiO2. Especially, a conduction electron polarizability of as high as near 100% has been found for the first time in high concentration W-doped anatase TiO2. It will be able to be a promising new type of dilute magnetic semiconductor. And the heavy W-doped anatase TiO2 make the band gap becomes narrower and absorption spectrum red-shift. PMID:25955308

  2. Synthesis and characterization of high photocatalytic activity and stable Ag3PO4/TiO2 fibers for photocatalytic degradation of black liquor

    NASA Astrophysics Data System (ADS)

    Cai, Li; Long, Qiyi; Yin, Chao

    2014-11-01

    The TiO2 fiber was prepared by using cotton fiber as a template, and then Ag3PO4/TiO2 fibers were synthesized via in situ Ag3PO4 particles onto the surface of TiO2 fiber. Their structure and physical properties were characterized by means of scanning electron microscopy (SEM), specific surface analyzer, X-ray diffraction (XRD), UV-vis absorption spectra and photoluminescence spectra (PL). SEM analysis indicated that the well-defined surface morphology of natural cotton fiber was mostly preserved in TiO2 and Ag3PO4/TiO2 fibers. Compared with TiO2 fiber, the absorbance wavelengths of Ag3PO4/TiO2 fibers were apparently red shifted and the PL intensities revealed a significant decrease. By using the photocatalytic degradation of black liquor as a model reaction, the visible light and ultraviolet light catalytic efficiencies of TiO2, Ag3PO4 and Ag3PO4/TiO2 fibers were evaluated. The reaction results showed that Ag3PO4/TiO2 fibers had stronger photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared Ag3PO4/TiO2 fibers could act as an efficient catalyst for the photocatalytic degradation of black liquor, which suggested their promising applications. It was proposed that the •OH radicals played the leading role in the photocatalytic degradation of the black liquor by Ag3PO4/TiO2 fibers system.

  3. Charge compensation in trivalent cation doped bulk rutile TiO2

    NASA Astrophysics Data System (ADS)

    Iwaszuk, Anna; Nolan, Michael

    2011-08-01

    Doping of TiO2 is a very active field, with a particularly large effort expended using density functional theory (DFT) to model doped TiO2; this interest has arisen from the potential for doping to be used in tuning the band gap of TiO2 for photocatalytic applications. Doping is also of importance for modifying the reactivity of an oxide. Finally, dopants can also be unintentionally incorporated into an oxide during processing, giving unexpected electronic properties. To unravel properly how doping impacts on the properties of a metal oxide requires a modelling approach that can describe such systems consistently. Unfortunately, DFT, as used in the majority of studies, is not suitable for application here and in many cases cannot even yield a qualitatively consistent description. In this paper we investigate the doping of bulk rutile TiO2 with trivalent cations, Al, Ga and In, using DFT, DFT corrected for on-site Coulomb interactions (DFT + U, with U on oxygen 2p states) and hybrid DFT (the screened exchange HSE06 exchange correlation functional) in an effort to better understand the performance of DFT in describing such fundamental doping scenarios and to analyse the process of charge compensation with these dopants. With all dopants, DFT delocalizes the oxygen hole polaron that results from substitution of Ti with the lower valence cation. DFT also finds an undistorted geometry and does not produce the characteristic polaron state in the band gap. DFT + U and hybrid DFT both localize the polaron, and this is accompanied by a distortion to the structure around the oxygen hole site. DFT + U and HSE06 both give a polaron state in the band gap. The band gap underestimation present in DFT + U means that the offset of the gap state from both the valence and the conduction band cannot be properly described, while the hybrid DFT offsets should be correct. We have investigated dopant charge compensation by formation of oxygen vacancies. Due to the large number of

  4. Characterization of nanocrystalline cobalt doped TiO2 sol-gel material

    NASA Astrophysics Data System (ADS)

    Siddhapara, Kirit; Shah, Dimple

    2012-08-01

    Nanocrystalline 1%, 2% and 4% Cobalt-doped TiO2 were prepared by sol-gel technique, followed by freeze-drying treatment at -30 °C temperature for 12 h. The obtained gels were thermally treated at 200, 400, 600 and 800 °C. X-ray Powder Diffraction (XRD), Scanning Electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDAX) were used to study its structural properties. The XRD pattern shows the coexistence of anatase phase and minor brookite phase. UV-vis Spectroscopy and Photoluminescence (PL) were used to study its optical properties. Optical band gap was calculated with the incorporation of different concentrations of cobalt. UV-visible spectroscopy shows variation in band gap for the sample treated at different temperatures for same concentration. All Cobalt doped TiO2 nanostructures show an appearance of Red shift relative to the bulk TiO2. The determination of magnetic properties was also carried out by Gouy balance method.

  5. Thermal analysis and temperature dependent dielectric responses of Co doped anatase TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Alamgir, Khan, Wasi; Ahmad, Shabbir; Ahammed, Nashiruddin; Naqvi, A. H.

    2015-05-01

    Nanoparticles (NPs) of pure and 5 mol % cobalt doped TiO2 synthesized through acid modified sol-gel method were characterized to understand their thermal, structural, morphological, and temperature dependent dielectric properties. Thermogravimetric analysis (TGA) has been used for thermal studies and indicates the weight loss in two steps due to the removal of residual organics. X-ray diffraction study was employed to confirm the formation of single anatase phase with tetragonal symmetry for both pure and 5 mol % Co doped TiO2 NPs. The average crystallite size of both samples was calculated from the Scherrer's formula and was found in the range from 9-11 nm. TEM micrographs of these NPs reflect their shape and distribution. The dielectric constant (ɛ'), dielectric loss (tanδ) and ac conductivity (σac) were also studied as a function of temperature at different frequencies. Electrical responses of the synthesized NPs have been analyzed carefully in the framework of relevant models. It is also noticed that the dielectric constant (ɛ') of the samples found to decrease with increasing frequency but increases with increasing temperature up to a particular value and then sharply decreases. Temperature variation of dielectric constant exhibits step like escalation and shows relaxation behavior. Study of dielectric properties shows dominant dependence on the grain size as well as Co ion incorporation in TiO2.

  6. Photocatalytic activity of Cr-doped TiO2 nanoparticles deposited on porous multicrystalline silicon films.

    PubMed

    Hajjaji, Anouar; Trabelsi, Khaled; Atyaoui, Atef; Gaidi, Mounir; Bousselmi, Latifa; Bessais, Brahim; El Khakani, My Ali

    2014-01-01

    This work deals with the deposition of Cr-doped TiO2 thin films on porous silicon (PS) prepared from electrochemical anodization of multicrystalline (mc-Si) Si wafers. The effect of Cr doping on the properties of the TiO2-Cr/PS/Si samples has been investigated by means of X-ray diffraction (XRD), atomic force microcopy (AFM), photoluminescence, lifetime, and laser beam-induced current (LBIC) measurements. The photocatalytic activity is carried out on TiO2-Cr/PS/Si samples. It was found that the TiO2-Cr/PS/mc-Si type structure degrades an organic pollutant (amido black) under ultraviolet (UV) light. A noticeable degradation of the pollutant is obtained for a Cr doping of 2 at. %. This result is discussed in light of LBIC and photoluminescence measurements. PMID:25313302

  7. Photocatalytic activity of Cr-doped TiO2 nanoparticles deposited on porous multicrystalline silicon films

    PubMed Central

    2014-01-01

    This work deals with the deposition of Cr-doped TiO2 thin films on porous silicon (PS) prepared from electrochemical anodization of multicrystalline (mc-Si) Si wafers. The effect of Cr doping on the properties of the TiO2-Cr/PS/Si samples has been investigated by means of X-ray diffraction (XRD), atomic force microcopy (AFM), photoluminescence, lifetime, and laser beam-induced current (LBIC) measurements. The photocatalytic activity is carried out on TiO2-Cr/PS/Si samples. It was found that the TiO2-Cr/PS/mc-Si type structure degrades an organic pollutant (amido black) under ultraviolet (UV) light. A noticeable degradation of the pollutant is obtained for a Cr doping of 2 at. %. This result is discussed in light of LBIC and photoluminescence measurements. PMID:25313302

  8. Synthesis and photocatalytic activity of N-doped TiO2 produced in a solid phase reaction

    NASA Astrophysics Data System (ADS)

    Xin, Gang; Pan, Hongfei; Chen, Dan; Zhang, Zhihua; Wen, Bin

    2013-02-01

    N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light.

  9. Electrical and electron paramagnetic resonance spectroscopy characterization of Mn-doped nanostructured TiO2 for capacitor applications

    NASA Astrophysics Data System (ADS)

    Vazquez-Reina, Rafael; Chao, Sheng; Petrovsky, Vladimir; Dogan, Fatih; Greenbaum, Steven

    2012-07-01

    Nanostructured TiO2 has shown promise as a dielectric material for high energy density ceramic capacitors because of its high dielectric breakdown strength and dielectric constant. Strategies to increase the insulation resistance or to reduce the leakage current of TiO2 include doping with transition metal ions. It is shown that Mn doping followed by an appropriate thermal treatment increases the grain boundary resistivity significantly and lowers the dielectric loss. Electrical measurements along with electron paramagnetic resonance and scanning electron microscopy of Mn-doped nanoscopic TiO2 demonstrate that sintering at 900 °C leads to optimal electrical properties that are correlated with a non-uniform distribution of dopant ions, concentrated at the grain boundaries. Nanostructured TiO2 dielectrics with improved insulation resistance are promising for the development of higher energy density capacitors.

  10. Surface Plasmons and Optical Properties of TiO2/X(X = Au and Ag) Nanostructure Thin Films

    NASA Astrophysics Data System (ADS)

    Zolanvari, A.; Sadeghi, H.; Norouzi, R.; Ranjgar, A.

    2013-09-01

    TiO2/X(X = Au and Ag) nanolayers are fabricated by depositing TiO2 films using rf magnetron sputtering on thin quartz substrates embedded with Au and Ag nanoparticles. Enhancement of light absorption of the nanostructural layers is observed. These plasmonic and non-plasmonic materials are ordered in geometric arrangements with dimensions that are fractions of the wavelength of light. The light absorption enhancement of synthesized structure in comparison to TiO2 is originated from near-field enhancement caused by the plasmonic effect of metallic nanoparticles, which can be demonstrated by the optical absorption spectra. We show that plasmon modes can exist for the infrared region of the optical spectrum. Also, we analyze the optical properties of the metal-insulator films, in order to clarify the role of metal inclusions in the TiO2 dielectric matrix. Optical band gaps of the nanolayer films are calculated by using Tauc's relation, and the n values of optical band gaps with the variation composition are found from 1.80 to 3.69 eV. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of TiO2/X(X=Au and Ag) nanolayers enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

  11. Enhanced photoelectrochemical water oxidation via atomic layer deposition of TiO2 on fluorine-doped tin oxide nanoparticle films

    NASA Astrophysics Data System (ADS)

    Cordova, Isvar A.; Peng, Qing; Ferrall, Isa L.; Rieth, Adam J.; Hoertz, Paul G.; Glass, Jeffrey T.

    2015-04-01

    TiO2 is an exemplary semiconductor anode material for photoelectrochemical (PEC) water-splitting electrodes due to its functionality, long-term stability in corrosive environments, nontoxicity, and low cost. In this study, TiO2 photoanodes with enhanced photocurrent density were synthesized by atomic layer deposition (ALD) of TiO2 onto a porous, transparent, and conductive fluorine-doped tin oxide nanoparticle (nanoFTO) scaffold fabricated by solution processing. The simplicity and disordered nature of the nanoFTO nanostructure combined with the ultrathin conformal ALD TiO2 coatings offers advantages including decoupling charge carrier diffusion length from optical penetration depth, increased photon absorption probability through scattering, complimentary photon absorption, and favorable interfaces for charge separation and transfer across the various junctions. We examine the effects of porosity of the nanoFTO scaffold and thickness of the TiO2 coating on PEC performance and achieve an optimal photocurrent of 0.7 mA cm-2 at 0 V vs. Ag/AgCl under 100 mW cm-2 AM 1.5 G irradiation in a 1 M KOH aqueous electrolyte. Furthermore, the fundamental mechanisms behind the improvements are characterized via cyclic voltammetry, incident photon-to-current efficiency, transient photocurrent spectroscopy, and electrochemical impedance spectroscopy and are contrasted with those of single crystal rutile TiO2 nanowires. The strategies employed in this work highlight the opportunities inherent to these types of heteronanostructures, where the lessons may be applied to improve the PEC conversion efficiencies of other promising semiconductors, such as hematite (α-Fe2O3) and other materials more sensitive to visible light.TiO2 is an exemplary semiconductor anode material for photoelectrochemical (PEC) water-splitting electrodes due to its functionality, long-term stability in corrosive environments, nontoxicity, and low cost. In this study, TiO2 photoanodes with enhanced photocurrent

  12. Room-temperature ferromagnetism in Co and Nb co-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hachisu, M.; Mori, K.; Hyodo, K.; Morimoto, S.; Yamazaki, T.; Ichiyanagi, Y.

    2015-02-01

    Co- and Nb-doped TiO2 nanoparticles encapsulated with amorphous SiO2 were synthesized by our novel preparation method. An anatase TiO2 single-phase structure was confirmed using X-ray diffraction. The particle size could be controlled to be about 5 nm. The composition of these nanoparticles was investigated by X-ray fluorescence analysis. X-ray absorption near-edge structure spectra showed that the Ti4+ and Co2+ states were dominant in our prepared samples. A reduction in the coordination number was also confirmed. The dependence of the electrical conductivity on the frequency was measured by an LCR meter, and the carrier concentration was determined. The magnetization curves for the nanoparticles indicated ferromagnetic behavior at room temperature. We concluded that the ferromagnetism originated in oxygen vacancies around the transition metal ions.

  13. The doping mechanism of Cr into TiO2 and its influence on the photocatalytic performance.

    PubMed

    Li, Xuemin; Guo, Zhengkai; He, Tao

    2013-12-14

    The chromium doped titanium dioxide (Cr-TiO2) has been synthesized using a hydrothermal method. The as-prepared samples have been characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HR-TEM), XPS valence band spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-vis DR), photoluminescence (PL) spectroscopy and time resolved PL (TR-PL) spectroscopy. The doping mechanism and related influence on the photocatalytic performance of TiO2 are thus proposed. The doped Cr(3+) ions can replace the Ti atoms in the lattice with oxygen vacancy compensation, distribute homogeneously in the framework of TiO2 crystals, and may make the n-type TiO2 less n-type or more p-type due to the resultant formation of oxygen vacancies, resulting in absorption of visible light, decrease of the intensity of PL emission and prolonged lifetime of photogenerated charge carriers. Compared with TiO2, the doped samples exhibit an improved visible-light photocatalytic activity. The influence of nitrogen modification has also been studied. We envision that these results would afford a better understanding of the doping mechanism of TiO2 using metal ions and, therefore, may provide a feasible way to prepare the TiO2-based photocatalysts for real applications. PMID:24154550

  14. Fabrication of bioactive, antibacterial TiO2 nanotube surfaces, coated with magnetron sputtered Ag nanostructures for dental applications.

    PubMed

    Uhm, Soo-Hyuk; Lee, Sang-Bae; Song, Doo-Hoon; Kwon, Jae-Sung; Han, Jeon-Geon; Kim, Kyoung-Nam

    2014-10-01

    We investigated whether a silver coating on an anodic oxidized titania (TiO2) nanotube surface would be useful for preventing infections in dental implants. We used a magnetron sputtering process to deposit Ag nanoparticles onto a TiO2 surface. We studied different sputtering input power densities and maintained other parameters constant. We used scanning electron microscopy, X-ray diffraction, and contact angle measurements to characterize the coated surfaces. Staphylococcus aureus was used to evaluate antibacterial activity. The X-ray diffraction analysis showed peaks that corresponded to metallic Ag, Ti, O, and biocompatible anatase phase TiO2 on the examined surfaces. The contact angles of the Ag nanoparticle-loaded surfaces were significantly lower at 2.5 W/cm2 input power under pulsed direct current mode compared to commercial, untreated Ti surfaces. In vitro antibacterial analysis indicated that a significantly reduced number of S. aureus were detected on an Ag nanoparticle-loaded TiO2 nanotube surface compared to control untreated surfaces. No cytotoxicity was noted, except in the group treated with 5 W/cm2 input power density, which was the highest input of power density we tested for the magnetron sputtering process. Overall, we concluded that it was feasible to create antibacterial Ag nanoparticle-loaded titanium nanotube surfaces with magnetron sputtering. PMID:25942879

  15. High power TiO2 and high capacity Sn-doped TiO2 nanomaterial anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lübke, Mechthild; Johnson, Ian; Makwana, Neel M.; Brett, Dan; Shearing, Paul; Liu, Zhaolin; Darr, Jawwad A.

    2015-10-01

    A range of phase-pure anatase TiO2 (∼5 nm) and Sn-doped TiO2 nanoparticles with the formula Ti1-xSnxO2 (where x = 0, 0.06, 0.11 and 0.15) were synthesized using a continuous hydrothermal flow synthesis (CHFS) reactor. Charge/discharge cycling tests were carried out in two different potential ranges of 3 to 1 V and also a wider range of 3 to 0.05 V vs Li/Li+. In the narrower potential range, the undoped TiO2 nanoparticles display superior electrochemical performance to all the Sn-doped titania crystallites. In the wider potential range, the Sn-doped samples perform better than undoped TiO2. The sample with composition Ti0.85Sn0.15O2, shows a capacity of ca. 350 mAh g-1 at an applied constant current of 100 mA g-1 and a capacity of 192.3 mAh g-1 at a current rate of 1500 mA g-1. After 500 charge/discharge cycles (at a high constant current rate of 382 mA g-1), the same nanomaterial anode retains a relatively high specific capacity of 240 mAh g-1. The performance of these nanomaterials is notable, particularly as they are processed into electrodes, directly from the CHFS process (after drying) without any post-synthesis heat-treatment, and they are made without any conductive surface coating.

  16. Controlled preparation of Ag nanoparticle films by a modified photocatalytic method on TiO2 films with Ag seeds for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Fu, Xin; Pan, Lujun; Li, Shuai; Wang, Qiao; Qin, Jun; Huang, Yingying

    2016-02-01

    Uniform Ag nanoparticle (NP) films were synthesized by a modified photocatalytic method on TiO2 films with Ag seeds for surface-enhanced Raman scattering, which combine the advantages of the spurting method (high nucleation density) and the traditional photocatalytic method (suitable particle size). The Ag seeds were prepared by magnetron sputtering with different time, which would adjust the distribution and transfer of electrons on the surface of TiO2 film in the process of photocatalytic reduction. The distribution and morphology of Ag NP films can be adjusted by the sputtering time and the UV irradiation time. The Raman enhancement of as-prepared Ag NP films was calculated by finite-difference time-domain to validate the experiment data. It is found that the Ag NP films synthesized on TiO2 films with suitable pre-deposited Ag seeds exhibit a much higher Raman enhancement activity than the optimum Ag NP film synthesized directly on the TiO2 film without Ag seeds.

  17. Si NW network by Ag nanoparticle assisted etching and TiO2/Si NWs as photodetector

    NASA Astrophysics Data System (ADS)

    Bhowmik, Kishan; Mondal, Aniruddha

    2015-03-01

    Glancing angle deposited silver (Ag) nanoparticles (NPs) were employed to fabricate the silicon (Si) nanowire (NW) network on p-type Si substrate. The Si NWs were characterized by X-ray diffraction, which shows the (311) oriented single crystalline nature. The FEG-SEM images show that the nanowire diameters are in the order of 60-180 nm. The photoluminescence emission at 525 nm was recognized from the Si NWs. The Ag-TiO2 contacts exhibit Schottky behavior and higher photoconduction was observed for TiO2-Si NW detector than that of TiO2 Thin film under illumination up to 2.5 V applied potential. A threefold enhanced photodetection for the Silicon nanowire device was observed compared to the TiO2 thin film device, under applied voltages of 0.4-1.5 V. [Figure not available: see fulltext.

  18. Optical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol-gel method

    NASA Astrophysics Data System (ADS)

    Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

    2013-12-01

    Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol-gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films.

  19. Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO2.

    PubMed

    Ozmen, Murat; Güngördü, Abbas; Erdemoglu, Sema; Ozmen, Nesrin; Asilturk, Meltem

    2015-08-01

    The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO2. Undoped and Mn-doped TiO2 nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO2 was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO2 nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO2 increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2-4h of degradation. However, biochemical assays showed that both Mn-doped TiO2 and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn-doped TiO2 should be considered due to nanomaterial applications and for spilled nanoparticles in an aquatic ecosystem. Also, the risk of nanoparticles should be considered using indicator reference biochemical markers to verify the environmental health impacts. PMID:26037099

  20. Enhancement removal of tartrazine dye using HCl-doped polyaniline and TiO2-decorated PANI particles

    NASA Astrophysics Data System (ADS)

    Elsayed, M. A.; Gobara, Mohamed

    2016-08-01

    HCl-doped polyaniline (HCl-PANI) and titanium dioxide decorated with polyaniline (TiO2-decorated PANI) with different TiO2:PANI ratios were chemically prepared and utilized for the removal of tartrazine (TZ) dye from a synthetic aqueous solution. The mechanism of preparation of the sample suggested that aniline was adsorbed on the TiO2 surface before the polymerization process took place. Samples were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy and x-ray diffraction. The results showed that HCl-PANI and TiO2-decorated PANI have an amorphous structure. The thermal stability of the prepared samples was characterized using thermo-gravimetric (TG) analysis. HCl-PANI is stable up to 200 °C and the relative weight per cent of PANI in the TiO2-decorated PANI was 20, 25, 40 and 45%. The removal activity of TiO2-decorated PANI via TZ azo dye was investigated under UV light irradiations and compared with HCl-PANI and TiO2 particles. The results indicated the superiority of the TiO2-decorated PANI over pure HCl-PANI and TiO2. However, the excessive PANI percentage tends to form a relatively thick layer, and even aggregates on the surface of TiO2. This hinders the migration of excited electrons from the outer PANI layer to the inner TiO2 particles, which consequently leads to a decrease in the removal efficiency. A possible mechanism for the removal oxidative degradation is also mentioned.

  1. Modification mechanism of praseodymium doping for the photocatalytic performance of TiO2: a combined experimental and theoretical study.

    PubMed

    Duan, Zhi-Gang; Zhao, Zong-Yan; Shi, Qing-Nan

    2015-07-15

    Impurity doping is a simple and efficient modification method to improve the photocatalytic performance of wide band gap photocatalysts. However, some basic and important issues about the mechanism of impurity doping modification still need to be further confirmed and explained. In the present work, Pr-doped TiO2 with a mono-phase crystal structure was prepared by a sol-gel method. Then, the crystal structure, binding information, optical absorption, and photocatalytic activity were systematically investigated. The experimental results show that Pr doping could significantly enhance the photocatalytic activity of TiO2, and the effects of modification on rutile TiO2 are more obvious than for anatase TiO2. In order to understand the underlying mechanism, density functional theory was utilized to calculate the crystal structure and electronic structure of pure and Pr-doped TiO2. The differences in electronic structure between anatase and rutile phases lead to the above photocatalytic performance. The experimental measurements and theoretical calculations mutually support each other in the present work. Two points are confirmed: the position of the band edge determines the redox activity of the photocatalyst, and the shallow energy bands induced by impurity doping could improve the photocatalytic performance. PMID:26130404

  2. Synthesis and characterization of zirconium-doped mesoporous nano-crystalline TiO2

    NASA Astrophysics Data System (ADS)

    Bineesh, Kanattukara Vijayan; Kim, Dong-Kyu; Park, Dae-Won

    2010-07-01

    A series of zirconium-doped nano-titania (Zr/TiO2) with various amounts of Zr were prepared by sol-gel method using titanium(iv) isopropoxide and zirconium nitrate as precursors. Zr/TiO2 samples were characterized using X-ray diffraction (XRD), surface area-pore volume measurements, infrared (FTIR) spectroscopy, UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric (TG) analysis, and transmission electron microscopy (TEM) techniques. XRD data and Raman spectra indicated that even after 5 mol% doping of zirconium in the crystal lattice of TiO2, the samples were phase pure with the anatase structure. The crystalline size of the anatase decreased with increasing Zr content. An increase in the BET surface area was also observed after doping of zirconium on nano-titania.

  3. Synthesis and characterization of zirconium-doped mesoporous nano-crystalline TiO2.

    PubMed

    Bineesh, Kanattukara Vijayan; Kim, Dong-Kyu; Park, Dae-Won

    2010-07-01

    A series of zirconium-doped nano-titania (Zr/TiO(2)) with various amounts of Zr were prepared by sol-gel method using titanium(iv) isopropoxide and zirconium nitrate as precursors. Zr/TiO(2) samples were characterized using X-ray diffraction (XRD), surface area-pore volume measurements, infrared (FTIR) spectroscopy, UV-vis-diffuse reflectance spectroscopy (UV-vis-DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, thermogravimetric (TG) analysis, and transmission electron microscopy (TEM) techniques. XRD data and Raman spectra indicated that even after 5 mol% doping of zirconium in the crystal lattice of TiO(2), the samples were phase pure with the anatase structure. The crystalline size of the anatase decreased with increasing Zr content. An increase in the BET surface area was also observed after doping of zirconium on nano-titania. PMID:20648353

  4. Defect Complex Effect in Nb Doped TiO2 Ceramics with Colossal Permittivity

    NASA Astrophysics Data System (ADS)

    Li, Fuchao; Shang, Baoqiang; Liang, Pengfei; Wei, Lingling; Yang, Zupei

    2016-07-01

    Donor-doped Nb x Ti1-x O2 (x = 1%, 2%, 4%, 6%, and 8%) ceramics with giant permittivity (>104) and a very low dielectric loss (˜0.05) were sintered under flowing N2 at 1400°C for 10 h. By increasing Nb doping concentration, two different dielectric responses were evidenced in the frequency dependence of dielectric properties of Nb doped TiO2 ceramics, which corresponded to the space charge polarization and the electron-pinned defect-dipoles effect, respectively. Especially, combined with the x-ray photoelectron spectroscopy results, the electron-pinned defect-dipoles induced by the 2({Nb}^{5 + } )_{{Ti}}^{ bullet } to 4({Ti}^{3 + } )^'_{{Ti}} leftarrow {V}_{{o}}^{ bullet bullet } defect complex were further confirmed to give rise to both their high ɛr and low tan δ in the high frequency range for the Nb x Ti1-x O2 ceramics with x > 4%.

  5. Visible light photocatalytic antibacterial activity of Ni-doped and N-doped TiO2 on Staphylococcus aureus and Escherichia coli bacteria.

    PubMed

    Ananpattarachai, Jirapat; Boonto, Yuphada; Kajitvichyanukul, Puangrat

    2016-03-01

    The Ni-doped and N-doped TiO2 nanoparticles were investigated for their antibacterial activities on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. Their morphological features and characteristics such as particle size, surface area, and visible light absorbing capacity were compared and discussed. Scanning electron microscopy, X-ray diffraction, and UV-visible spectrophotometry were used to characterize both materials. The inactivation of E. coli (as an example of Gram-negative bacteria) and S. aureus (as an example of Gram-positive bacteria) with Ni-doped and N-doped TiO2 was investigated in the absence and presence of visible light. Antibacterial activity tests were conducted using undoped, Ni-doped, and N-doped TiO2. The N-doped TiO2 nanoparticles show higher antibacterial activity than Ni-doped TiO2. The band gap narrowing of N-doped TiO2 can induce more visible light absorption and leads to the superb antibacterial properties of this material. The complete inactivation time for E. coli at an initial cell concentration of 2.7 × 10(4) CFU/mL was 420 min which is longer than the 360 min required for S. aureus inactivation. The rate of inactivation of S. aureus using the doped TiO2 nanoparticles in the presence of visible light is greater than that of E. coli. The median lethal dose (LD50) values of S. aureus and E. coli by antibacterial activity under an 18-W visible light intensity were 80 and 350 mg/ml for N-doped TiO2, respectively. PMID:26028352

  6. Europium Doped TiO2 Hollow Nanoshells: Two-Photon Imaging of Cell Binding

    PubMed Central

    Sandoval, Sergio; Yang, Jian; Alfaro, Jesus G.; Liberman, Alexander; Makale, Milan; Chiang, Casey E.; Schuller, Ivan K.

    2012-01-01

    A simple scalable method to fabricate luminescent monodisperse 200 nm europium doped hollow TiO2 nanoshell particles is reported. Fluorophore reporter, Eu3+ ions, are incorporated directly in the NS matrix, leaving the surface free for functionalization and the core free for payload encapsulation. Amine functionalized polystyrene beads were used as templates, and the porous walls of europium doped titania nanoshells were synthesized using titanium(IV) t-butoxide and europium(III) nitrate as reactants. X-ray diffraction analysis identified anatase as the predominant titania phase of the rigid nanoshell wall structure, and photoluminescence spectra showed that the Eu(III) doped TiO2 nanoshells exhibited a red emission at 617 nm due to an atomic f-f transition. Nanoshell interactions with HeLa cervical cancer cells in vitro were visualized using two-photon microscopy of the Eu(III) emission, and studied using a luminescence ratio analysis to assess nanoshell adhesion and endocytosis. PMID:23185106

  7. TiO2 doped UO2 fuels sintered by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Yao, Tiankai; Scott, Spencer M.; Xin, Guoqing; Lian, Jie

    2016-02-01

    UO2 fuels doped with oxide additives Cr2O3 and TiO2 display larger grain size, improving fission product retention capability and thus accident tolerance. Spark plasma sintering (SPS) was applied to consolidate TiO2-doped UO2 fuel pellets with 0.5 wt % dopant concentration, above its solubility, in order to induce eutectic phase formation and promote sintering kinetics. The grain size can reach 80 μm by sintering at 1700 °C for 20 min, and liquid U-Ti-O eutectic phase occurs at the triple junction of grain boundaries and significantly improves grain growth during sintering. The oxide additive also impedes the reduction of the initial hyperstoichiometric fuel powders to more stoichiometric fuel pellets upon SPS process. Thermal-mechanical properties of the sintered doped fuel pellets including thermal conductivity and hardness are measured and compared with undoped fuel pellets. The enlarged grain size (80 μm) and densification within short sintering duration highlight the immense possibility of SPS in fabricating large grained UO2 fuel pellets to improve fuel performance.

  8. Monodisperse spherical mesoporous Eu-doped TiO2 phosphor particles and the luminescence properties

    NASA Astrophysics Data System (ADS)

    Yin, Jianbo; Xiang, Liqin; Zhao, Xiaopeng

    2007-03-01

    Monodisperse spherical and mesoporous Eu-doped TiO2 phosphor particles were prepared by nonionic surfactant-assisted soft-chemistry method. It is shown that the phosphor particles possess submicron diameter of about 250nm and narrow size distribution. Under ultraviolet irradiation the particles show characteristic luminescence corresponding to D05-Fj7 of Eu3+. Especially, the calcined particles consisted of mesopores and semicrystalline framework shows the strongest photoluminescence compared to the amorphous particles without annealing and the completely crystalline particles annealed at higher temperature. This is attributed to the energy transfer from titania nanocrystallite to Eu3+ ions dispersed in glassy amorphous titania region.

  9. Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO2)/TiO2 heterojunction semiconductors with varied Sb doping concentration

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen-Long; Ma, Wen-Hai; Mao, Yan-Li

    2014-09-01

    In this paper, antimony-doped tin oxide (Sb-SnO2) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO2/TiO2 heterojunction semiconductors were prepared with Sb-SnO2 and TiO2. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO2 and TiO2, Sb-SnO2/TiO2 presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO2/TiO2 composed of Sb-SnO2 with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO2 and TiO2 in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO2 and TiO2 were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO2/TiO2 composed of Sb-SnO2 with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.

  10. Hydrothermal synthesis of Mo-doped VO2/TiO2 composite nanocrystals with enhanced thermochromic performance.

    PubMed

    Li, Dengbing; Li, Ming; Pan, Jing; Luo, Yuanyuan; Wu, Hao; Zhang, Yunxia; Li, Guanghai

    2014-05-14

    This paper reports a one-step TiO2 seed-assistant hydrothermal synthesis of Mo-doped VO2(M)/TiO2 composite nanocrystals. It was found that excess Mo doping can promote formation of the VO2(M) phase, and rutile TiO2 seed is beneficial to morphology control, size reduction, and infrared modulation of Mo-doped VO2(M) nanocrystals. The Mo-doped VO2 nanocrystals epitaxially grow on TiO2 seeds and have a quasi-spherical shape with size down to 20 nm and a nearly 35% infrared modulation near room temperature. The findings of this work demonstrate important progress in the near-room-temperature thermochromic performance of VO2(M) nanomaterials, which will find potential application in constructing VO2(M) nanocrystal-based smart window coatings. PMID:24734771

  11. P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method

    NASA Astrophysics Data System (ADS)

    Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

    2014-11-01

    Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

  12. Preparation and photocatalytic activity of B, Ce Co-doped TiO2 hollow fibers photocatalyst

    NASA Astrophysics Data System (ADS)

    Qiu, Jingping; Sun, Xiaogang; Xing, Jun; Liu, Xiaobo

    2014-07-01

    A series of B, Ce co-doped TiO2 (B, Ce-TiO2) photocatalytic materials with a hollow fiber structure were successfully prepared by template method using boric acid, ammonium ceric nitrate and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500°C in an N2 atmosphere for 2 h. Scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption measurements, and UV-visible spectroscopy (UV-Vis) were employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photocatalytic performance of the samples was studied by photodegradation phenol in water under UV light irradiation. The results showed that the TiO2 fiber materials have hollow structures, and the fiber structure materials showed better photocatalytic properties for the degradation of phenol than pure TiO2 under UV light. In the experiment condition, the photocatalytic activity of B, Ce co-doped TiO2 fibers was optimal of all the prepared samples. In addition, the possibility of cyclic usage of B, Ce co-doped TiO2 fiber photocatalyst was also confirmed, the photocatalytic activity of TiO2 fibers remained above 90% of that of the fresh sample after being used four times. The material was easily removed by centrifugal separation from the medium. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

  13. Low Temperature Hydrothermal Synthesis of Visible-Light-Activated I-Doped TiO2 for Improved Dye Degradation.

    PubMed

    Wang, Dongting; Li, Jianwen; Zhou, Guangsheng; Wang, Wenxu; Zhang, Xianxi; Pan, Xu

    2016-06-01

    Iodine doped TiO2 with different iodine/Ti molar ratios has been firstly synthesized with a low temperature hydrothermal route and has been studied systematically in photocatalysis under visible light condition. The resulting iodine doped TiO2 were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance investigations were conducted by means of the degradation of Rhodamine B (RhB) under the visible light irradiation in aqueous solution. Under an optimized I/Ti doping ratio of 10 mol%, the photocatalytic performance is greatly better, with degradation efficiency of 95%, which is almost double that of pure TiO2. The superior photocatalytic activity of iodine-doped TiO2 could be mainly attributed to extended visible light absorption originated from the formation of continuous states existed in the band gap of the doped TiO2 introduced by iodine. Active oxygen species, that is, *OH and O2-, were evidenced to be involved in the degradation process and a possible mechanism was also proposed. PMID:27427614

  14. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    PubMed Central

    2013-01-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

  15. Colossal Dielectric Behavior of Ga+Nb Co-Doped Rutile TiO2.

    PubMed

    Dong, Wen; Hu, Wanbiao; Berlie, Adam; Lau, Kenny; Chen, Hua; Withers, Ray L; Liu, Yun

    2015-11-18

    Stimulated by the excellent colossal permittivity (CP) behavior achieved in In+Nb co-doped rutile TiO2, in this work we investigate the CP behavior of Ga and Nb co-doped rutile TiO2, i.e., (Ga(0.5)Nb(0.5))(x)Ti(1-x)O2, where Ga(3+) is from the same group as In(3+) but with a much smaller ionic radius. Colossal permittivity of up to 10(4)-10(5) with an acceptably low dielectric loss (tan δ = 0.05-0.1) over broad frequency/temperature ranges is obtained at x = 0.5% after systematic synthesis optimizations. Systematic structural, defect, and dielectric characterizations suggest that multiple polarization mechanisms exist in this system: defect dipoles at low temperature (∼10-40 K), polaronlike electron hopping/transport at higher temperatures, and a surface barrier layer capacitor effect. Together these mechanisms contribute to the overall dielectric properties, especially apparent observed CP. We believe that this work provides comprehensive guidance for the design of new CP materials. PMID:26512874

  16. Niobium Doping Effects on TiO2 Mesoscopic Electron Transport Layer-Based Perovskite Solar Cells.

    PubMed

    Kim, Dong Hoe; Han, Gill Sang; Seong, Won Mo; Lee, Jin-Wook; Kim, Byeong Jo; Park, Nam-Gyu; Hong, Kug Sun; Lee, Sangwook; Jung, Hyun Suk

    2015-07-20

    Perovskite solar cells (PSCs) are the most promising candidates as next-generation solar energy conversion systems. To design a highly efficient PSC, understanding electronic properties of mesoporous metal oxides is essential. Herein, we explore the effect of Nb doping of TiO2 on electronic structure and photovoltaic properties of PSCs. Light Nb doping (0.5 and 1.0 at %) increased the optical band gap slightly, but heavy doping (5.0 at %) distinctively decreased it. The relative Fermi level position of the conduction band is similar for the lightly Nb-doped TiO2 (NTO) and the undoped TiO2 whereas that of the heavy doped NTO decreased by as much as ∼0.3 eV. The lightly doped NTO-based PSCs exhibit 10 % higher efficiency than PSCs based on undoped TiO2 (from 12.2 % to 13.4 %) and 52 % higher than the PSCs utilizing heavy doped NTO (from 8.8 % to 13.4 %), which is attributed to fast electron injection/transport and preserved electron lifetime, verified by transient photocurrent decay and impedance studies. PMID:25891531

  17. Photoelectrochemical behavior of Nb-doped TiO2 electrodes.

    PubMed

    Emeline, Alexei V; Furubayashi, Yutaka; Zhang, Xintong; Jin, Ming; Murakami, Taketoshi; Fujishima, Akira

    2005-12-29

    The photoelectrochemical behavior of degenerate Nb-doped TiO2 (Ti(1-x)Nb(x)O2: x = 0, 0.01, 0.03, 0.06, 0.1) electrodes prepared by pulsed laser deposition on LaAlO3 (LAO) and SrTiO3 (STO) was examined, revealing that an increase in Nb concentration causes a significant decay of titania photoactivity. One reason for such behavior may be a Burstein-Moss effect, which leads to a blue shift of the spectral limit of photoactivity. Another reason typical for metal-doped photocatalysts is the increase of the efficiency of charge carrier recombination. PMID:16375445

  18. Electrode effects in dielectric spectroscopy measurements on (Nb +In) co-doped TiO2

    NASA Astrophysics Data System (ADS)

    Crandles, David; Yee, Susan; Savinov, Maxim; Nuzhnyy, Dimitri; Petzelt, Jan; Kamba, Stanislav; Prokes, Jan

    Recently, several papers reported the discovery of giant permittivity and low dielectric loss in (Nb+In) co-doped TiO2. A series of tests was performed which included the measurement of the frequency dependence of the dielectric permittivity and ac conductivity of co-doped (Nb+In)TiO2 as a function of electrode type, sample thickness and temperature. The data suggest that the measurements are strongly affected by the electrodes. The consistency between four contact van der Pauw dc conductivity measurements and bulk conductivity values extracted from two contact ac conductivity measurements suggest that the values of colossal permittivity are, at least in part, a result of Schottky barrier depletion widths that depend on electrode type and temperature. Nserc, Czech Science Foundation (Project 15-08389S).

  19. Preparation and Solar Light Photocatalytic Activity of N-Doped TiO2-Loaded Halloysite Nanotubes Nanocomposites

    NASA Astrophysics Data System (ADS)

    Cheng, Zhi-Lin; Sun, Wei

    2015-10-01

    A novel method to prepare N-doped TiO2-loaded halloysite nanotubes (N-TiO2/HNTs) nanocomposites was achieved by using the chemical vapor deposition in autoclave. The N-TiO2/HNTs nanocomposites obtained by the different form of the doping N source were studied through a series of characterizations. The XRD, SEM, and TEM characterizations verified the anatase structure of TiO2 nanoparticles with the size of ca.20nm loaded on the outer surface of HNTs. The UV-vis characterization of the N-TiO2/HNTs presented a further red-shift compared to the pure N-TiO2 nanoparticles.. The XPS characterizations confirmed the N element doped into the crystal structure of TiO2 nanoparticles. The photocatalytic activities of N-TiO2/HNTs nanocomposites prepared were evaluated by degradation of phenol at room temperature under simulated solar light irradiation.

  20. Rutile to anatase phase transition induced by N doping in highly oriented TiO2 films.

    PubMed

    Breeson, Andrew C; Sankar, Gopinathan; Goh, Gregory Kia Liang; Palgrave, Robert G

    2016-09-21

    Highly oriented TiO2 thin films were deposited onto Al2O3(0001), SrTiO3(001), and LaAlO3(001) substrates by spin coating a titanium alkoxide precursor solution followed by annealing. The films were nitrogen doped by two different routes: either by adding tetramethyethylenediamine (TMEDA) to the precursor solution or alternatively by high temperature ammonolysis. Undoped TiO2 films were highly oriented and the phase was dependent on the substrate. N doping by ammonolysis led to transformation of rutile films to anatase, confirmed by XRD and by XPS valence band spectroscopy. Significant differences were observed in the spatial distribution of the nitrogen dopant depending upon which synthesis method was used. These two factors may shed light on the increased photocatalytic efficiencies reported in N doped TiO2. PMID:27546382

  1. Photochromism-based detection of volatile organic compounds by W-doped TiO2 nanofibers.

    PubMed

    Jin, Ming; Zhang, Xintong; Pu, Hongting; Nishimoto, Shunsuke; Murakami, Taketoshi; Fujishima, Akira

    2011-10-01

    W-doped TiO(2) nanofibers with various compositions (W/Ti: 2-8%) were fabricated by the electrospinning method from respective precursor solutions containing tungsten(V) pentaethoxide, titanium tetraisopropoxide (TTIP), and polyvinylpyrrolidone (PVP), followed with calcination at 550 °C. Morphological and structural characteristics of these nanofibers were studied with SEM, XRD and XPS. W-doping inhibited the crystal growth and anatase-to-rutile transformation of TiO(2) nanofibers. W-doped TiO(2) nanofiber mats showed good photocatalytic oxidation abilities for acetone. Obvious color change from white to blue of mats during the photocatalysis process can be detected by naked eyes, which provides a good way in detection of pollutants in indoor air, especially for the volatile organic compounds (VOCs). PMID:21741658

  2. SiO2/TiO2/n-Si/Ag(Cr)/TiO2 thin films with superhydrophilicity and low-emissivity

    NASA Astrophysics Data System (ADS)

    Loka, Chadrasekhar; Ryeol Park, Kyoung; Lee, Kee-Sun

    2016-01-01

    In this study, SiO2/TiO2/n-Si/Ag(Cr)/TiO2 multilayer structures have been designed and deposited by the RF and DC magnetron sputtering at room temperature. The as-deposited TiO2/glass films which are initially amorphous in nature were subjected to post annealing at 673 K for anatase phase TiO2. The anatase TiO2 films showed an optical bandgap ˜3.32 eV. The Ag(Cr)/TiO2 showed very low-emissivity (low-e) value ˜0.081 which is evaluated by using the sheet resistance (6.51 Ω/□) of the films. All the deposited films showed high visible transmittance (˜81%) and high infrared reflectance (72%) which are recorded by using the UV-vis-NIR spectrophotometer. In addition, experimentally obtained optical properties were in good agreement with the simulation data. The TiO2/n-Si heterojunction concept has been employed to enhance the superhydrophilicity of the deposited multilayer stack, TiO2/n-Si/Ag(Cr)/TiO2 films exhibited best superhydrophilicity with water contact angle ˜2°. The deposited multilayer structures SiO2/TiO2/n-Si/Ag(Cr)/TiO2 and TiO2/n-Si/Ag(Cr)/TiO2 achieved significant low-e and superhydrophilicity.

  3. Bacteria Adherence Properties of Nitrogen-Doped TiO2 Coatings by Plasma Surface Alloying Technique

    NASA Astrophysics Data System (ADS)

    Wang, Hefeng; Tang, Bin; Li, Xiuyan; Fan, Ailan

    Titanium nitride coatings on 316L stainless steel (S. S) were obtained by plasma surface alloying technique. Nitrogen-doped titanium dioxide (TiO2-xNx) was synthesized by oxidative annealing the resulted TiNx coatings in air. The reference TiO2 samples were also prepared by oxidation of sputtered Ti coatings. The as-prepared coatings were characterized by X-ray diffraction, glow discharge optical emission spectrometer (GDOES), scanning electron microscopy, X-ray hotoelectron spectroscopy and UV-Vis spectrophotometry, respectively. The bacteria adherence property of the TiO2-xNx coatings on stainless steel on the oral bacteria Streptococcus Mutans was investigated and compared with that of stainless steel by fluorescence microscopy. The mechanism of the bacteria adherence was discussed. The results show that the TiO2-xNx coatings are composed of anatase crystalline structure. SEM measurement indicates a rough surface morphology with three-dimensional homogenous protuberances after annealing treatment. Optical properties reveal an extended tailing of the absorption edge toward the visible region due to nitrogen presence. The band gap of the N-doped sample is reduced from 2.29 eV to 1.90 eV compared with the pure TiO2 one. Because of the different roughness and microstructure, the TiO2-xNx coatings inhibit the bacteria adherence.

  4. Energetic, electronic and optical properties of lanthanide doped TiO2: An ab initio LDA+U study

    NASA Astrophysics Data System (ADS)

    Mulwa, Winfred M.; Ouma, Cecil N. M.; Onani, Martin O.; Dejene, Francis B.

    2016-05-01

    Substitutional energies, thermodynamic charge transition levels and optical properties of lanthanide doped anatase TiO2 has been investigated using local density approximation with the Hubbard U correction (LDA+U) within the density functional theory formalism. All the lanthanides apart from La introduced impurity states in the host band gap on doping. The calculated substitutional energies indicate that it is possible to dope TiO2 with lanthanide ions. The optimal doping percentage was predicted to be ~3% and dopant levels resulting from Ce, Nd, Sm, Gd and Tm doping were found to possess negative U characteristics. In addition the calculated thermodynamic transition levels predicted Lu as not having any possible charge transitions within the host band gap. The calculated optical absorption coefficients indicate that lanthanide doping led to optical absorption in the visible regime.

  5. Visible light photocatalytic degradation of 4-chlorophenol using vanadium and nitrogen co-doped TiO2

    NASA Astrophysics Data System (ADS)

    Jaiswal, R.; Patel, N.; Kothari, D. C.; Miotello, A.

    2013-02-01

    Vanadium and Nitrogen were codoped in TiO2 photocatalyst by Sol-gel method to utilize visible light more efficiently for photocatalytic reactions. A noticeable shift of absorption edge to visible light region was obtained for the singly-doped namely V-TiO2, N-TiO2 and codoped V-N-TiO2 samples in comparison with undoped TiO2, with smallest band gap obtained with codoped-TiO2. The photocatalytic activities for all TiO2 photocatalysts were tested by 4-chlorophenol (organic pollutant) degradation under visible light irradiation. It was found that codoped TiO2 exhibits the best photocatalytic activity, which could be attributed to the synergistic effect produced by V and N dopants.

  6. Recyclable three-dimensional Ag nanoparticle-decorated TiO2 nanorod arrays for surface-enhanced Raman scattering.

    PubMed

    Fang, Hui; Zhang, Chang Xing; Liu, Luo; Zhao, Yong Mei; Xu, Hai Jun

    2015-02-15

    Multifunctional Ag nanoparticle-decorated TiO2 nanorod arrays were prepared by two simple processes. TiO2 nanorod arrays were first fabricated by the hydrothermal route and then Ag nanoparticles were decorated on the nanorods by the chemical reduction impregnation method. Three-dimensional Ag/TiO2 arrays were used as an active substrate for surface-enhanced Raman scattering (SERS). The results show that the detection limit for rhodamine 6G (R6G) was as low as 10(-7)M and the Raman enhancement factor was as large as 10(5). After calibrating the Raman peak intensities of R6G, it could be quantitatively detected. More importantly, the photocatalytic activity of TiO2 provides a self-cleaning capability to the SERS substrate, which can be recycled and used to degrade many Ag surface adsorbates such as R6G, methyl orange, Congo red, and methylene blue after exposure to visible light. The absorbed small molecules can all be rapidly and completely removed from the SERS substrate, which has been successfully reused four times without a decrease in accuracy or sensitivity. Our results reveal that the unique recyclable property not only paves a new way to solve the single-use problem of traditional SERS substrates but also provides more SERS platforms for multiple detections of other organic molecular species. PMID:25282397

  7. Photodeposition of Ag2S on TiO2 nanorod arrays for quantum dot-sensitized solar cells

    PubMed Central

    2013-01-01

    Ag2S quantum dots were deposited on the surface of TiO2 nanorod arrays by a two-step photodeposition. The prepared TiO2 nanorod arrays as well as the Ag2S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag2S quantum dots on the ordered TiO2 nanorod arrays. UV–vis absorption spectra of Ag2S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm2 with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm2 was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm2. PMID:23286551

  8. Synthesis of Ag or Pt nanoparticle-deposited TiO2 nanorods for the highly efficient photoreduction of CO2 to CH4

    NASA Astrophysics Data System (ADS)

    Wang, Qingli; Dong, Peimei; Huang, Zhengfeng; Zhang, Xiwen

    2015-10-01

    Ag or Pt-deposited TiO2 nanocomposites were prepared by a simple method, in which oriented TiO2 nanorods were synthesized by a hydrothermal method and a noble metal (Ag or Pt) was deposited on TiO2 by photocatalytic reduction under UV irradiation. The oriented TiO2 nanorods with Ag or Pt nanoparticles (<20 nm) exhibited high CO2 photoreduction efficiency, with CH4 yield rates up to 16.0 ppm/g h and 10.8 ppm/g h, respectively, considerably higher than that of the pure TiO2 nanorods (4.2 ppm/g h). The improvement in the CH4 yield was attributed to the formation of a Schottky barrier and surface plasmon resonance.

  9. The growth of Ag films on a TiO 2(110)-(1×1) surface

    NASA Astrophysics Data System (ADS)

    Su, C.; Yeh, J.-C.; Lin, J.-L.; Lin, J.-C.

    2001-01-01

    We report here the growth of Ag film and its thermal stability on the TiO 2(1 1 0)-(1×1) surface using combination techniques of low-energy ion scattering (LEIS), X-ray photoelectron spectroscopy (XPS), and low-energy electron diffraction (LEED). At a surface temperature as low as 125 K, a 2D growth of Ag films seems to occur for submonolayer coverages up to ˜0.8 ML. Annealing of low temperature grown Ag films to 500 K for coverage of 1-2.4 ML would result in the formation of metastable Ag layers with rest of Ag forming 3D needle-like islands on top of this Ag film.

  10. Preparation and Characterization of Ni-Doped TiO2 Materials for Photocurrent and Photocatalytic Applications

    PubMed Central

    Ganesh, Ibram; Gupta, A. K.; Kumar, P. P.; Sekhar, P. S. C.; Radha, K.; Padmanabham, G.; Sundararajan, G.

    2012-01-01

    Different amounts of Ni-doped TiO2 (Ni = 0.1 to 10%) powders and thin films were prepared by following a conventional coprecipitation and sol-gel dip coating techniques, respectively, at 400 to 800°C, and were thoroughly characterized by means of XRD, FT-IR, FT-Raman, DRS, UV-visible, BET surface area, zeta potential, flat band potential, and photocurrent measurement techniques. Photocatalytic abilities of Ni-doped TiO2 powders were evaluated by means of methylene blue (MB) degradation reaction under simulated solar light. Characterization results suggest that as a dopant, Ni stabilizes TiO2 in the form of anatase phase, reduces its bandgap energy, and adjusts its flat band potentials such that this material can be employed for photoelectrochemical (PEC) oxidation of water reaction. The photocatalytic activity and photocurrent ability of TiO2 have been enhanced by doping of Ni in TiO2. The kinetic studies revealed that the MB degradation reaction follows the Langmuir-Hinshelwood first-order reaction relationship. PMID:22619580

  11. Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis

    PubMed Central

    Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

    2015-01-01

    This study developed a facile approach for preparing Ti3+ self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti3+ doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti3+ in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications. PMID:25716132

  12. Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

    2015-02-01

    This study developed a facile approach for preparing Ti3+ self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti3+ doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti3+ in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications.

  13. Fabrication of Au@Ag core/shell nanoparticles decorated TiO2 hollow structure for efficient light-harvesting in dye-sensitized solar cells.

    PubMed

    Yun, Juyoung; Hwang, Sun Hye; Jang, Jyongsik

    2015-01-28

    Improving the light-harvesting properties of photoanodes is promising way to enhance the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). We synthesized Au@Ag core/shell nanoparticles decorated TiO2 hollow nanoparticles (Au@Ag/TiO2 HNPs) via sol-gel reaction and chemical deposition. The Au@Ag/TiO2 HNPs exhibited multifunctions from Au@Ag core/shell NPs (Au@Ag CSNPs) and TiO2 hollow nanoparticles (TiO2 HNPs). These Au@Ag CSNPs exhibited strong and broadened localized surface plasmon resonance (LSPR), together with a large specific surface area of 129 m(2) g(-1), light scattering effect, and facile oxidation-reduction reaction of electrolyte from TiO2 HNPs, which resulted in enhancement of the light harvesting. The optimum PCE of η = 9.7% was achieved for the DSSCs using photoanode materials based on TiO2 HNPs containing Au@Ag/TiO2 HNPs (0.2 wt % Au@Ag CSNPs with respect to TiO2 HNPs), which outperformed by 24% enhancement that of conventional photoanodes formed using P25 (η = 7.8%). PMID:25562329

  14. Synthesis, characterization, and photoconductivity studies on nanocrystalline TiO2 films doped with gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Valverde-Aguilar, G.; García-Macedo, J. A.; Galván-Ramírez, P.; Rentería-Tapia, V.

    2009-08-01

    Nanocrystalline TiO2 films doped with gold nanoparticles were synthesized by the sol-gel process at room temperature. The TiO2 films were synthesized by using tetrabutyl orthotitanate as the inorganic precursor. The films were spin-coated on glass wafers. The samples were annealed at 100°C for 30 minutes and sintered at 520°C for 1 hour to generated anatase and rutile phases. The films were characterized using UV-Vis absorption spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. An absorption peak located at around 651 nm is due to the surface plasmon resonance of the gold nanoparticles. Optical absorption spectrum was fitted by Gans model by using a high refractive index (nlocal = 2.6). This high index is related to the high content of anatase nanoparticles embedded in the film. Photoconductivity studies were performed on nanocrystalline (anatase phase) 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. Transport parameters were calculated. Results are discussed.

  15. Nd-Doping Induced Lattice Distortion in TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Wu, Da-Jian; Yang, Yue-Tao; Liu, Xiao-Jun

    2011-02-01

    Nd-doping effects are investigated in TiO2 nanoparticles with various annealing temperatures T from 70°C to 1100°C by means of x-ray diffraction (XRD) and Raman scattering spectroscopy. XRD results indicate that the sample shows a rutile phase at 1100°C, which changes to anatase phase at 900°C. With decreasing T down to 300°C, a significant lattice shrink is found, that is, the lattice parameter c is significantly suppressed while the a value shows a gradual decrease. With further decrease of T, the c-value shows an unexpected increase while the α-value keeps a gradual decrease. Thus, a lattice distortion takes place with changing the annealing temperature. In Raman investigation, all the Raman modes for the anatase phase show hardening behaviors with decreasing T in the range 900-300°C, and then the Eg and A1g modes show softening behaviors below 300°C, suggesting the variation of the lattice distortion. The variation of the lattice distortion at different annealing temperatures is ascribed to different depositions of Nd ions on the surface of TiO2 nanoparticles.

  16. Copper and nitrogen doping on TiO2 photoelectrodes and their functions in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Park, Jun-Yong; Kim, Chan-Soo; Okuyama, Kikuo; Lee, Hye-Moon; Jang, Hee-Dong; Lee, Sung-Eun; Kim, Tae-Oh

    2016-02-01

    The influence of Cu doping on the function of dye-sensitized solar cells (DSSCs) dependent on Cu/N-doped TiO2 photoelectrodes was examined. Cu/N-doped TiO2 photoelectrodes with diverse Cu concentration were synthesized using the sol-gel process. Upon adequate addition of Cu, the nanoparticles exhibited small particle sizes, high surface area, and a significant red alteration of their absorption to the visible region in relation to Degussa P25 nanomaterials. Furthermore, the traces of Cu/N-doped TiO2 nanoparticles enhanced the charge transfer and reduced the charge recombination. The addition of sufficient Cu and N increased the surface area, elevating the dye adsorption degree, and decreasing the level of electron recombination. A DSSC fabricated with a 1 mM Cu/N-doped TiO2 nanoparticles accomplished 11.35% of the highest power conversion efficiency, with a short-circuit current of 22.5 mA/cm2. The energy conversion efficiency of this photoelectrode was approximately 37% greater than that of the control, Degussa P25. The increased energy efficiency can be resulted from the extension in surface area, which enabled larger dye charging amount, and the deduction in charge recombination, which accelerated the charge transfer.

  17. Enhanced electron transport in Nb-doped TiO2 nanoparticles via pressure-induced phase transitions.

    PubMed

    Lü, Xujie; Yang, Wenge; Quan, Zewei; Lin, Tianquan; Bai, Ligang; Wang, Lin; Huang, Fuqiang; Zhao, Yusheng

    2014-01-01

    Anatase TiO2 is one of the most important energy materials but suffers from poor electrical conductivity. Nb doping has been considered as an effective way to improve its performance in the applications of photocatalysis, solar cells, Li batteries, and transparent conducting oxide films. Here, we report the further enhancement of electron transport in Nb-doped TiO2 nanoparticles via pressure-induced phase transitions. The phase transition behavior and influence of Nb doping in anatase Nb-TiO2 have been systematically investigated by in situ synchrotron X-ray diffraction and Raman spectroscopy. The bulk moduli are determined to be 179.5, 163.3, 148.3, and 139.0 GPa for 0, 2.5, 5.0, and 10.0 mol % Nb-doped TiO2, respectively. The Nb-concentration-dependent stiffness variation has been demonstrated: samples with higher Nb concentrations have lower stiffness. In situ resistance measurements reveal an increase of 40% in conductivity of quenched Nb-TiO2 in comparison to the pristine anatase phase. The pressure-induced conductivity evolution is discussed in detail in terms of the packing factor model, which provides direct evidence for the rationality of the correlation of packing factors with electron transport in semiconductors. Pressure-treated Nb-doped TiO2 with unique properties surpassing those in the anatase phase holds great promise for energy-related applications. PMID:24320708

  18. Enhanced lithium ion storage in TiO2 nanoparticles, induced by sulphur and carbon co-doping

    NASA Astrophysics Data System (ADS)

    Ivanov, Svetlozar; Barylyak, Adriana; Besaha, Khrystyna; Dimitrova, Anna; Krischok, Stefan; Bund, Andreas; Bobitski, Jaroslav

    2016-09-01

    Sulphur and carbon codoped anatase nanoparticles are synthesized by one-step approach based on interaction between thiourea and metatitanic acid. Electron microscopy shows micrometer-sized randomly distributed crystal aggregates, consisting of many 25-40 nm TiO2 nanoparticles. The obtained phase composition and chemical states of the elements in the structure are analyzed by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD shows that after doping the tetragonal anatase structure is preserved. Further data assessment by Rietveld refinement allows detection of a slight increase of the c lattice parameter and volume related to incorporation of the doping elements. XPS confirms the coexistence of both elemental and oxide carbon forms, which are predominantly located on the TiO2 particle surface. According to XPS analysis sulphur occupies titanium sites and the element is present in S6+ sulfate environment. Analysis based on cyclic voltammetry and galvanostatic intermittent titration (GITT) suggests an accelerated Li+ transport in the doped TiO2 structure. The synthesized S and C co-doped anatase has an excellent electrochemical performance in terms of capacity and very fast lithiation kinetics, superior to the non-doped TiO2. The material displays 83% capacity retention for 500 galvanostatic cycles and nearly 100% current efficiency.

  19. Zirconium-doped and silicon-doped TiO2 photocatalysts synthesis from ionic-liquid-like precursors.

    PubMed

    Estruga, Marc; Domingo, Concepción; Domènech, Xavier; Ayllón, José A

    2010-04-15

    Nanocrystalline titania powders doped with either zirconium or silicon were synthesized at low temperature via destabilization of ionic-liquid-like precursors. Titania materials prepared at low temperature (85 degrees C) consisted of anatase nanocrystals of about 25 nm, according to powder X-ray diffraction and transmission electron microscopy. Dopant incorporation was evaluated using inductively coupled plasma-optical emission spectrometry, and it was found that dopant/titanium ratios in the powder (0.011 for Zr and 0.026 for Si) were lower than those in the precursor (0.11 for both). Low-temperature nitrogen adsorption-desorption isotherms displayed the characteristic hysteresis loop of mesoporous materials. Specific surface areas reached values of 130 and 155 m(2) g(-1) for Zr-doped and Si-doped TiO(2), respectively. The photocatalytic activity of the synthesized nanopowders was tested using methyl orange and 4-chlorophenol as target pollutants. PMID:20138629

  20. Microcystin-LR removal from aqueous solutions using a magnetically separable N-doped TiO2 nanocomposite under visible light irradiation

    EPA Science Inventory

    The performance of magnetically separable N-doped TiO2 was found to be significantly improved when compared with a non-magnetic N-doped TiO2 for the aqueous removal of cyanotoxin Microcystin-LR. The observed enhanced photocatalytic activity may be related to the presence of ferri...

  1. Fabrication and investigation of gas sensing properties of Nb-doped TiO2 nanotubular arrays

    NASA Astrophysics Data System (ADS)

    Galstyan, Vardan; Comini, Elisabetta; Faglia, Guido; Vomiero, Alberto; Borgese, Laura; Bontempi, Elza; Sberveglieri, Giorgio

    2012-06-01

    Synthesis of Nb-containing titania nanotubular arrays at room temperature by electrochemical anodization is reported. Crystallization of pure and Nb-doped TiO2 nanotubes was carried out by post-growth annealing at 400 °C. The morphology of the tubes obtained was characterized by scanning electron microscopy (SEM). Crystal structure and composition of tubes were investigated by glancing incidence x-ray diffraction (GIXRD) and total reflection x-ray fluorescence (TXRF). For the first time gas sensing characteristics of Nb-doped TiO2 nanotubes were investigated and compared to those of undoped nanotubes. The functional properties of nanotubular arrays towards CO, H2, NO2, ethanol and acetone were tested in a wide range of operating temperature. The introduction of Nb largely improves conductivity and enhances gas sensing performances of TiO2 nanotubes.

  2. Effect of nitrogen doping on the performance of dye-sensitized solar cells composed of mesoporous TiO2 photoelectrodes.

    PubMed

    Eom, Ki Heon; Yun, Tae Kwan; Hong, Jin-Yeon; Bae, Jae Young; Huh, Seong; Won, Yong Sun

    2014-12-01

    Nitrogen-doped mesoporous TiO2 (NMP TiO2) nanoparticles are synthesized using a soft triblock copolymer template by TiCl4 hydrolysis with ammonia water and applied to the photoelectrodes of dye-sensitized solar cells (DSSCs). The large surface area of a TiO2 mesoporous structure is favorable for dye uptake, and nitrogen doping of TiO2 is expected to increase the charge transport in the photoelectrode as well as the scattering of visible light. Structural characterizations for NMP TiO2 nanoparticles by XRD, XPS, BET, and BJH analyses revealed successful synthesis. However, the photovoltaic performances of the DSSCs prepared from NMP TiO2 were not improved, as had been expected: the photo-conversion efficiency (η) of DSSCs from undoped mesoporous TiO2 (MP TiO2) was 4.69%, an improvement over the 4.15% with the application of P25 TiO2, but the efficiency of DSSCs from NMP TiO2 decreased to 3.2-3.6%. The measured amounts of adsorbed dye showed that nitrogen doping did not significantly affect dye adsorption. Therefore, it can be concluded that nitrogen doping increases isotropic charge transport in a TiO2 nanoparticle to promote charge recombination into an electrolyte, despite its advantages. The full benefits of nitrogen doping may be obtained through measures such as the deposition of a thin barrier layer of oxide onto the TiO2 surface to prevent charge recombination during charge transport in the TiO2 network. PMID:25971066

  3. Effects of acceptor-donor complexes on electronic structure properties in co-doped TiO2: A first-principles study

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Cai, L. L.; Yuan, X. B.; Hu, G. C.; Ren, J. F.

    2016-07-01

    We theoretically investigate the doping effects induced by impurity complexes on the electronic structures of anatase TiO2 based on the density functional theory. Mono-doping and co-doping effects are discussed separately. The results show that the impurity doping can make the band-edges shift. The induced defect levels in the band gaps by impurity doping reduce the band gap predominantly. The compensated acceptor-donor pairs in the co-doped TiO2 will improve the photoelectrochemical activity. From the calculations, it is also found that (S+Zr)-co-doped TiO2 has the ideal band gap and band edge, at the same time, the binding energy is higher than other systems, so (S+Zr)-co-doping in TiO2 is more promise in photoelectrochemical experiments.

  4. Decorated TiO2 Nanoparticles with La and Ag Elements to Improve Photocatalytic Activity Under Visible Light for the Degradation of MO.

    PubMed

    Wang, Qinghua; Gao, Xuechuan; Zhang, Renfei; Shen, Beibei; Tan, Zhibing; Li, Zhao; Yu, Shiyong

    2016-04-01

    Visible-light photocatalyst of TiO2/La/Ag nanocomposites were successfully synthesized via the conventional sol-gel method and reducing agent of Ag+. The photocatalytic activities were evaluated by methyl orange (MO) degradation. They have remarkable photocatalytic activities compared to TiO2-Anatase, which is thanks to the separation of electron-hole pairs by Ag nanoparticles and lanthanum. The products were characterized by a series of techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Uv-vis. The results show that spherical nanocomposites have been prepared with the size 300 nm and Ag nanoparticles (~10 nm) are dispersed uniformly onto the surface of TiO2/La, which forms TiO2/La/Ag nanocomposites. TiO2/La/Ag nanocomposites have good absorption in the visible region (700 nm > λ > 400 nm). The reasons are as follows: (1) the efficient separation of photogenerated electrons and holes of the photocatalysts on the surface of TiO2/La/Ag nanocomposites and (2) a wide visible-light photoabsorption range (700 nm > λ > 400 nm). Therefore, this study may provide some new idea for the rational design and the facile synthesis of composite catalysts with a green, efficient pathway. PMID:27451670

  5. Enhanced sunlight photocatalytic activity of Ag3PO4 decorated novel combustion synthesis derived TiO2 nanobelts for dye and bacterial degradation.

    PubMed

    Eswar, Neerugatti KrishnaRao; Ramamurthy, Praveen Chandrashekarapura; Madras, Giridhar

    2015-07-01

    This study demonstrates the synthesis of TiO2 nanobelts using solution combustion derived TiO2 with enhanced photocatalytic activity for dye degradation and bacterial inactivation. Hydrothermal treatment of combustion synthesized TiO2 resulted in unique partially etched TiO2 nanobelts and Ag3PO4 was decorated using the co-precipitation method. The catalyst particles were characterized using X-ray diffraction analysis, BET surface area analysis, diffuse reflectance and electron microscopy. The photocatalytic properties of the composites of Ag3PO4 with pristine combustion synthesized TiO2 and commercial TiO2 under sunlight were compared. Therefore the studies conducted proved that the novel Ag3PO4/unique combustion synthesis derived TiO2 nanobelt composites exhibited extended light absorption, better charge transfer mechanism and higher generation of hydroxyl and hole radicals. These properties resulted in enhanced photodegradation of dyes and bacteria when compared to the commercial TiO2 nanocomposite. These findings have important implications in designing new photocatalysts for water purification. PMID:26056065

  6. Novel Fe doped mesoporous TiO 2 microspheres: Ultrasonic-hydrothermal synthesis, characterization, and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Li, Haibin; Liu, Guocong; Chen, Shuguang; Liu, Qicheng

    2010-04-01

    Novel Fe doped mesoporous TiO 2 microspheres were fabricated by an ultrasonic-hydrothermal method when tetrabutyl titanate was used as a precursor and octadecylamine was used as a structure-directing agent. The mesoporous materials were characterized by XRD, SEM, TEM, N 2 adsorption-desorption measurements, XPS, FL, and UV-vis. The results suggest that both ultrasonic treatment and hydrothermal procedure are critical for the fabrication of Fe doped mesoporous TiO 2 microspheres with a combination of regular morphology, large specific surface area, high crystallinity, and high thermal stability. Low-angle XRD and TEM images indicate that the disordered wormhole-like mesostructure of Fe doped TiO 2 microspheres with diameters of about 300-400 nm is actually formed by the agglomerization of nanoparticles with an average size of about 10 nm. The photocatalytic activity of Fe doped mesoporous TiO 2 microspheres was evaluated by the photodegradation of methyl orange. A small amount of Fe 3+ can obviously enhance their photocatalytic activity. The optimal atomic ratio of Fe to Ti for photocatalytic activity is about 0.5 at%.

  7. Synthesis of N-doped TiO2 Using Guanidine Nitrate: An Excellent Visible Light Photocatalyst

    EPA Science Inventory

    An excellent visible light active nitrogen-rich TiO2 photocatalyst have been synthesized by using guanidine nitrate as the doping material. The catalytic efficiency of the catalyst has been demonstrated by the decomposition of the dye, methyl orange (MO), and the pollutant, 2,4 d...

  8. TiO 2 thin films doped with Pd and Eu for optically and electrically active TOS-Si heterojunction

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Danuta; Domaradzki, Jaroslaw; Prociow, Eugeniusz L.; Berlicki, Tadeusz; Prociow, Krystyna

    2009-07-01

    In this work, optical and electrical characterization of transparent Eu and Pd-doped TiO 2 thin films has been presented. Thin films of TiO 2 doped with Eu (0.9 at.%) and Pd (5.8 at.%) were deposited on silicon and glass substrates from Ti-Eu-Pd mosaic target using modified magnetron sputtering method. X-ray diffraction measurements revealed nanocrystalline structure with the only rutile phase of TiO 2 in prepared thin films. Pd-doping, through formation of discontinuous paths for charge carriers brings the enhanced electrical conductivity and makes prepared thin films oxide semiconductors. It has been shown, that Eu dopant acts as an optical activator of light conversion from UV to the red-visible, corresponding to the optical working range of standard silicon devices. From electrical measurements it was found out that Eu-doping of TiO 2 results in the n-type of electrical conduction. From optical transmission spectroscopy measurements position of the fundamental absorption edge and optical band-gap energy have been determined. The current to voltage dependence and photovoltage observations confirmed the formation of heterojunction at thin film-silicon interface.

  9. Enhanced photocatalytic generation of hydrogen by Pt-deposited nitrogen-doped TiO2 hierarchical nanostructures

    NASA Astrophysics Data System (ADS)

    Naik, Brundabana; Moon, Song Yi; Kim, Sang Hoon; Park, Jeong Young

    2015-11-01

    We report the photocatalytic activity of hydrogen generation on Pt nanoparticles deposited on hierarchically porous N-doped TiO2 nanostructures (Pt-NHPT). The photocatalysts are composed of Pt nanoparticles well dispersed throughout hierarchical macroporous TiO2 fibrous channels. The interstitial N doping extends light absorption toward the visible region. We found that the porosity of N-doped TiO2 nanostructures can be tuned using different annealing temperatures. While Pt-NHPT catalysts calcined at 300 °C (Pt-NHPT-300) have both macro- and mesoporosity, Pt-NHPT catalysts calcined at 800 °C (Pt-NHPT-800) exhibit only macroporosity. We found that Pt-NHPT-300 shows a two-fold higher H2 evolution activity than that of Pt-NHPT-800, and 30% higher activity than undoped hierarchical catalysts (Pt-HPT-300). The enhanced photoactivity is attributed to the synergistic effects of N doping, hierarchical porosity, and charge transfer between the TiO2 nanostructures and the Pt co-catalyst.

  10. Carbamazepine degradation using a N-doped TiO2 coated photocatalytic membrane reactor: Influence of physical parameters.

    PubMed

    Horovitz, Inna; Avisar, Dror; Baker, Mark A; Grilli, Rossana; Lozzi, Luca; Di Camillo, Daniela; Mamane, Hadas

    2016-06-01

    Commercial α-Al2O3 photocatalytic membranes with a pore size of 200 and 800-nm were coated with N-doped TiO2 photocatalytic film using a sol-gel technique for concurrent bottom-up filtration and photocatalytic oxidation. X-ray diffraction confirmed that the deposited N-doped TiO2 films are in the form of anatase with 78-84% coverage of the membrane surface. The concentration of N found by X-ray photoelectron spectroscopy was in the range of 0.3-0.9 atomic percentage. Membrane permeability after coating decreased by 50% and 12% for the 200- and 800-nm membrane substrates, respectively. The impact of operational parameters on the photocatalytic activity (PCA) of the N-doped TiO2-coated membranes was examined in a laboratory flow cell based on degradation of the model micropollutant carbamazepine, using a solar simulator as the light source. The significant gap in degradation rate between flow through the membrane and flow on the surface of the membrane was attributed both to the hydraulic effect and in-pore PCA. N-doped TiO2-coated membranes showed enhanced activity for UV wavelengths, in addition to activity under visible light. Experiments of PCA under varying flow rates concluded that the process is in the mass-transfer control regime. Carbamazepine removal rate increased with temperature, despite the decrease in dissolved oxygen concentration. PMID:26900981

  11. Mechanism of strong visible light photocatalysis by Ag2O-nanoparticle-decorated monoclinic TiO2(B) porous nanorods.

    PubMed

    Paul, Kamal Kumar; Ghosh, Ramesh; Giri, P K

    2016-08-01

    We report on the ultra-high rate of photodegradation of organic dyes under visible light illumination on Ag2O-nanoparticle-decorated (NP) porous pure B-phase TiO2 (TiO2(B)) nanorods (NRs) grown by a solvothermal route. The as-grown TiO2(B) NRs are found to be nanoporous in nature and the Ag2O NPs are uniformly decorated over its surface, since most of the pores work as nucleation sites for the growth of Ag2O NPs. The effective band gap of the TiO2(B)/Ag2O heterostructure (HS), with a weight ratio of 1:1, has been significantly reduced to 1.68 eV from the pure TiO2(B) band gap of 2.8 eV. Steady state and time-resolved photoluminescence (PL) studies show the reduced intensity of visible PL and slower recombination dynamics in the HS samples. The photocatalytic degradation efficiency of the TiO2(B)/Ag2O HS has been investigated using aqueous methyl orange and methylene blue as reference dyes under visible light (390-800 nm) irradiation. It is found that photodegradation by the TiO2(B)/Ag2O HS is about one order of magnitude higher than that of bare TiO2(B) NRs and Ag2O NPs. The optimized TiO2(B)/Ag2O HS exhibited the highest photocatalytic efficiency, with 88.2% degradation for 30 min irradiation. The corresponding first order degradation rate constant is 0.071 min(-1), which is four times higher than the reported values. Furthermore, cyclic stability studies show the high stability of the HS photocatalyst for up to four cycles of use. The major improvement in photocatalytic efficiency has been explained on the basis of enhanced visible light absorption and band-bending-induced efficient charge separation in the HS. Our results demonstrate the long-term stability and superiority of the TiO2(B)/Ag2O HS over the bare TiO2(B) NRs and other TiO2-based photocatalysts for its cutting edge application in hydrogen production and environmental cleaning driven by solar light photocatalysis. PMID:27333816

  12. Mechanism of strong visible light photocatalysis by Ag2O-nanoparticle-decorated monoclinic TiO2(B) porous nanorods

    NASA Astrophysics Data System (ADS)

    Paul, Kamal Kumar; Ghosh, Ramesh; Giri, P. K.

    2016-08-01

    We report on the ultra-high rate of photodegradation of organic dyes under visible light illumination on Ag2O-nanoparticle-decorated (NP) porous pure B-phase TiO2 (TiO2(B)) nanorods (NRs) grown by a solvothermal route. The as-grown TiO2(B) NRs are found to be nanoporous in nature and the Ag2O NPs are uniformly decorated over its surface, since most of the pores work as nucleation sites for the growth of Ag2O NPs. The effective band gap of the TiO2(B)/Ag2O heterostructure (HS), with a weight ratio of 1:1, has been significantly reduced to 1.68 eV from the pure TiO2(B) band gap of 2.8 eV. Steady state and time-resolved photoluminescence (PL) studies show the reduced intensity of visible PL and slower recombination dynamics in the HS samples. The photocatalytic degradation efficiency of the TiO2(B)/Ag2O HS has been investigated using aqueous methyl orange and methylene blue as reference dyes under visible light (390–800 nm) irradiation. It is found that photodegradation by the TiO2(B)/Ag2O HS is about one order of magnitude higher than that of bare TiO2(B) NRs and Ag2O NPs. The optimized TiO2(B)/Ag2O HS exhibited the highest photocatalytic efficiency, with 88.2% degradation for 30 min irradiation. The corresponding first order degradation rate constant is 0.071 min‑1, which is four times higher than the reported values. Furthermore, cyclic stability studies show the high stability of the HS photocatalyst for up to four cycles of use. The major improvement in photocatalytic efficiency has been explained on the basis of enhanced visible light absorption and band-bending-induced efficient charge separation in the HS. Our results demonstrate the long-term stability and superiority of the TiO2(B)/Ag2O HS over the bare TiO2(B) NRs and other TiO2-based photocatalysts for its cutting edge application in hydrogen production and environmental cleaning driven by solar light photocatalysis.

  13. Low-temperature solvothermal synthesis of visible-light-responsive S-doped TiO2 nanocrystal

    NASA Astrophysics Data System (ADS)

    Yang, Guidong; Yan, Zifeng; Xiao, Tiancun

    2012-02-01

    In this work, a low-temperature solvothermal method has been developed to synthesize visible-light-responsive S-doped TiO2 nanocrystal photocatalyst, using thiourea as the sulfur source to enhance sulfur incorporation into TiO2 lattice. The effects of different S:Ti molar ratio on the crystal structure, chemical composition, surface property and catalytic performance have been studied. X-ray photoelectron spectroscopy (XPS) analysis and Fourier transform infrared (FT-IR) spectra displayed that the TiO2 was modified by the S element incorporated into the TiO2 network to form Tisbnd Osbnd S bond, which therefore led to the formation of intermediate energy level just above the O 2p valance band, and caused the absorption edge of TiO2 to shift into the visible light region up to 500 nm. Characterization results show that the pure nanocrystal anatase structure, with both the degree of S doping and oxygen vacancies makes contribution to the exceptional photocatalytic activity of TONS in visible-light degradation of Methylene Blue (MB) and phenol molecules.

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

    NASA Astrophysics Data System (ADS)

    Song, Myoung Geun; Bark, Chung Wung

    2016-06-01

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

  15. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  16. Combination study of DFT calculation and experiment for photocatalytic properties of S-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Liu, Rujun; Zhou, Xiaosong; Yang, Fan; Yu, Ying

    2014-11-01

    Although there are many publications about S-doped TiO2, the related mechanism is still not well elucidated. In order to investigate the origin and trend of S substituting for O in TiO2 crystal lattice with proper dopant concentration, a combination of DFT calculation and experiment was used. Bader charge and electronic location function analysis indicate that the largely ionic character between Ti and S bonding in titanium dioxide decreases and there is free electron gas like behavior around S and neighbor Ti for the S-doped anatase TiO2. From DFT calculation, ST2.78 model is found to stabilize the structure of S substitution for lattice O with lower formation energy and its absorbance in visible light increases. Experiment results demonstrate that the sulfur doping results in the shift of the absorption edge for TiO2 to lower energy region, which leads to the nanoparticles active within the wavelength range of 650 nm.

  17. A Pt-Doped TiO2 Nanotube Arrays Sensor for Detecting SF6 Decomposition Products

    PubMed Central

    Zhang, Xiaoxing; Tie, Jing; Zhang, Jinbin

    2013-01-01

    The detection of partial discharge and analysis of SF6 gas components in gas-insulated switchgear (GIS) is important for the diagnosis and operating state assessment of power equipment. The use of a Pt-doped TiO2 nanotube arrays sensor for detecting sulfur hexafluoride (SF6) decomposition products is proposed in this paper. The electrochemical pulse deposition method is employed to prepare the sensor array. The sensor's response to the main characteristic gaseous decomposition products of SF6 is evaluated. The gas sensing characteristic curves of the Pt-doped TiO2 nanotube sensor and intrinsic TiO2 nanotube arrays sensor are compared. The mechanism of the sensitive response is discussed. Test results showed that the Pt-doped nanoparticles not only change the gas sensing selectivity of the TiO2 nanotube arrays sensor with respect to the main characteristic SF6 decomposition products, but also reduce the operating temperature of the sensor. PMID:24177728

  18. Improve efficiency of perovskite solar cells by using Magnesium doped ZnO and TiO2 compact layers

    NASA Astrophysics Data System (ADS)

    Baktash, Ardeshir; Amiri, Omid; Sasani, Alireza

    2016-05-01

    Here the effect of Magnesium doped TiO2 and ZnO as hole blocking layers (HBLs) are investigated by using solar cell capacitance simulator (SCAPS). The Impact of Magnesium concentration into the TiO2 and ZnO and effect of operating temperature on the performance of the perovskite solar cell are investigated. Best cell performance for both TiO2 and ZnO HBLs (with cell efficiencies of 19.86% and 19.57% respectively) are concluded for the doping level of 10% of Mg into the structure of HBLs. Increase in operating temperature from 300 K to 400 K are decreased the performance of the perovskite solar cell with both pure and Mg-doped HBLs. However, the cells with pure ZnO layer and with Zn0.9 Mg0.1O layer show the highest (with a decline of 8.88% in efficiency) and the lowest stability (with a decline of 50.49% in efficiency) at higher temperatures respectively. Moreover, the cell with Ti0.9 Mg0.1O2 layer shows better stability (with 21.85% reduction in efficiency) than the cell with pure TiO2 compact layer (with 23.28% reduction in efficiency) at higher operating temperatures.

  19. First-principles GGA+U study of the different conducting properties in pentavalent-ion-doped anatase and rutile TiO2

    NASA Astrophysics Data System (ADS)

    Yang, Kesong; Dai, Ying; Huang, Baibiao; Feng, Yuan Ping

    2014-07-01

    The electronic properties of pentavalent-ion (Nb5+, Ta5+, and I5+) doped anatase and rutile TiO2 are studied using spin-polarized GGA + U calculations. Our calculated results indicate that these two phases of TiO2 exhibit different conductive behavior upon doping. For doped anatase TiO2, some up-spin-polarized Ti 3d states lie near the conduction band bottom and cross the Fermi level, showing an n-type half-metallic character. For doped rutile TiO2, the Fermi level is pinned between two up-spin-polarized Ti 3d gap states, showing an insulating character. In addition to the Nb (Ta)-doped anatase TiO2, we propose that the I-doped anatase TiO2 can also be a potential transparent conducting oxide, which is worthy of further experimental verification. These findings clarify the long-standing controversy of whether GGA + U calculation can successfully predict the conducting property in the Nb (Ta)-doped anatase phase and the insulating property in the rutile phase. Moreover, our results show that the symmetry breaking can cause a metal-insulating transition in pentavalent-ion-doped anatase TiO2, though this symmetry breaking may not occur spontaneously because of the relatively high energy barrier.

  20. Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer

    PubMed Central

    2011-01-01

    We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte. PMID:21777458

  1. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M.; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%).

  2. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells.

    PubMed

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%). PMID:26758549

  3. Enhanced electronic properties in mesoporous TiO2 via lithium doping for high-efficiency perovskite solar cells

    PubMed Central

    Giordano, Fabrizio; Abate, Antonio; Correa Baena, Juan Pablo; Saliba, Michael; Matsui, Taisuke; Im, Sang Hyuk; Zakeeruddin, Shaik M.; Nazeeruddin, Mohammad Khaja; Hagfeldt, Anders; Graetzel, Michael

    2016-01-01

    Perovskite solar cells are one of the most promising photovoltaic technologies with their extraordinary progress in efficiency and the simple processes required to produce them. However, the frequent presence of a pronounced hysteresis in the current voltage characteristic of these devices arises concerns on the intrinsic stability of organo-metal halides, challenging the reliability of technology itself. Here, we show that n-doping of mesoporous TiO2 is accomplished by facile post treatment of the films with lithium salts. We demonstrate that the Li-doped TiO2 electrodes exhibit superior electronic properties, by reducing electronic trap states enabling faster electron transport. Perovskite solar cells prepared using the Li-doped films as scaffold to host the CH3NH3PbI3 light harvester produce substantially higher performances compared with undoped electrodes, improving the power conversion efficiency from 17 to over 19% with negligible hysteretic behaviour (lower than 0.3%). PMID:26758549

  4. Synthesis of Metal Ion-Doped TiO2 Nanoparticles Using Two-Phase Method and Their Photocatalytic Activity Under Visible Light Irradiation.

    PubMed

    Nguyen, Duy-Trinh; Hong, Seong-Soo

    2016-02-01

    In this study, TiO2 and metal ion-doped TiO2 nanoparticles were successfully synthesized by solvothermal reaction of titanium butoxide precursor in the presence of oleic acid, oleylamine and vapor water and they were characterized by XRD, Raman, TEM and DRS. We also investigated the photocatalytic activity of these oxides for the decomposition of Rhodamine B. From XRD and Raman results, doping of the metal ion in the crystal lattice did not change the high crystallinity of the TiO2 structure, and all the metal ions were incorporated into the structures of titania as well as replaced titanium ion or located at interstitial site. The absorption band shifted to a higher wavelength on the metal ion-doped TiO2 samples compared to the pure TiO2 sample. The Ce ion- doped TiO2 catalysts showed the higher photocatalytic activity compared to the pure TiO2 and a commercial P-25 catalysts and 1% Ce-doped TiO2 showed the highest photocatalytic activity. PMID:27433699

  5. First-principles study of the electronic structure of nonmetal-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Wang, Yuan; Ma, Jing; Zhou, Jian-Ping; Chen, Xiao-Ming; Wang, Jing-Zhou

    2016-02-01

    In this paper, we present a detailed study of the structure, defect formation energy, and electronic and magnetic properties of nonmetal-doped TiO2 by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). The formation energy reduces with increasing electronegativity of the dopant. After doping with nonmetal elements, some band gaps of the doped-TiO2 become narrow, and others become wide, in which impurity states appear in the band gap. The relative positions of the impurity states are much different, mainly caused by the different electronegativities of the nonmetal elements F, O, B, C and N. When H is added to achieve a charge balance, the impurity states approach the valence band maximum, because the electronegativity difference among the nonmetal elements is decreased. Therefore, nonmetal and H codoping is an effective way to improve the visible-light catalytic activity of anatase TiO2. In addition, N-doping and C-doping can cause spin polarization of the TiO2 electronic structure and form 1.0 μ B and 2.0 μ B magnetic moment, respectively.

  6. Photocatalytic degradation of acephate in pak choi, Brassica chinensis, with Ce-doped TiO2.

    PubMed

    Liu, Xiangying; Wang, Lifeng; Zhou, Xiaomao; Liu, Kailin; Bai, Lianyang; Zhou, Xuguo

    2015-01-01

    The photocatalytic degradation of acephate was investigated using Ce-doped TiO2 (TiO2/Ce) hydrosol. In contrast to previous research conducted under artificial light in the laboratory, this study investigated the decomposition of acephate in a field trial. The results show that acephate can be efficiently degraded by the TiO2/Ce system under natural field conditions; the degradation efficiency was affected by the dosage of the photocatalyst and acephate. The optimum dosage of TiO2/Ce was 2400 g a.i.ha(-1), and the photodegradation efficiency of acephate reached 93.5% after 20 h at an acephate dosage of 675 g a.i.ha(-1). Ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) analysis detected and identified four degradation products-methamidophos, phosphorothioic acid O,O,S-trimethyl ester, S-methyl methanethiosulfonate and phosphorous acid-that were formed during the TiO2/Ce photodegradation of acephate. Based on the structural identification of the degradation products, a probable photodegradation pathway was proposed, and the first decomposition step may be the cleavage of the C‒N bond of acephate. Subsequently, the P‒S and P‒O bonds may be oxidized gradually or simultaneously to complete the mineralization. PMID:25826101

  7. Influence of transition metal doping on the structural, optical, and magnetic properties of TiO2 films deposited on Si substrates by a sol–gel process

    PubMed Central

    2013-01-01

    Transition metal (TM)-doped TiO2 films (TM = Co, Ni, and Fe) were deposited on Si(100) substrates by a sol–gel method. With the same dopant content, Co dopants catalyze the anatase-to-rutile transformation (ART) more obviously than Ni and Fe doping. This is attributed to the different strain energy induced by the different dopants. The optical properties of TM-doped TiO2 films were studied with spectroscopic ellipsometry data. With increasing dopant content, the optical band gap (EOBG) shifts to lower energy. With the same dopant content, the EOBG of Co-doped TiO2 film is the smallest and that of Fe-doped TiO2 film is the largest. The results are related to electric disorder due to the ART. Ferromagnetic behaviors were clearly observed for TM-doped TiO2 films except the undoped TiO2 film which is weakly magnetic. Additionally, it is found that the magnetizations of the TM-doped TiO2 films decrease with increasing dopant content. PMID:24350904

  8. TiO2 modified with Ag nanoparticles synthesized via ultrasonic atomization-UV reduction and the use of kinetic models to determine the acetic acid photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Xu, Yingcao; You, Hong

    2014-12-01

    TiO2 surfaces modified with noble metal nanoparticles have been found to effectively reduce the photogenerated carrier recombination rate and significantly extend the light absorption properties of TiO2, thereby greatly increasing its photocatalytic activity. In this paper, highly ordered, double-sided TiO2 nanotube arrays were prepared using an anodic oxidation method in a home-made reactor using glycerol/water (volume ratio 2:1) and NH4F (0.25 mol/L) as the electrolyte, titanium plates (10 cm × 2 cm × 0.5 mm) as the anode and graphite as the cathode at a constant voltage of 25 V. After a 2-h reaction, anatase TiO2 nanotubes were obtained upon calcination at 450 °C for 4 h. The Ag nanoparticles on the surfaces of the TiO2 were prepared via ultrasonic atomization-ultraviolet light reduction. First, a silver nitrate solution was sputtered into small droplets under ultrasonication. Then, the Ag+ droplets were reduced to Ag nanoparticles. The surface morphologies, structures and elemental compositions were characterized using SEM, EDS, XRD and XPS. The photocatalytic activities were determined in acetic acid solutions (40-200 mg/L), and a mathematical model for catalytic degradation was established based on a hyperbolic model. The SEM results showed that the diameters of the as-prepared Ag/TiO2 are approximately 100 nm and that the lengths are approximately 1.8 μm. The XRD crystal structure analysis shows that the anatase phase of the TiO2 does not change during the Ag modification, and there was a peak from Ag (2 2 0). The XPS determined that the Ag atom percentage was 1.11%. The degradation of acetic acid indicated that Ag/TiO2 has a higher photocatalytic activity than the undoped TiO2.

  9. Synergistic effect on the visible light activity of Ti3+ doped TiO2 nanorods/boron doped graphene composite

    PubMed Central

    Xing, Mingyang; Li, Xiao; Zhang, Jinlong

    2014-01-01

    TiO2/graphene (TiO2-x/GR) composites, which are Ti3+ self-doped TiO2 nanorods decorated on boron doped graphene sheets, were synthesized via a simple one-step hydrothermal method using low-cost NaBH4 as both a reducing agent and a boron dopant on graphene. The resulting TiO2 nanorods were about 200 nm in length with exposed (100) and (010) facets. The samples were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, X-band electron paramagnetic resonance (EPR), X-ray photoelectron spectra (XPS), transmission electron microscope (TEM), Raman, and Fourier-transform infrared spectroscopy (FTIR). The XRD results suggest that the prepared samples have an anatase crystalline structure. All of the composites tested exhibited improved photocatalytic activities as measured by the degradation of methylene blue and phenol under visible light irradiation. This improvement was attributed to the synergistic effect of Ti3+ self-doping on TiO2 nanorods and boron doping on graphene. PMID:24974890

  10. A stable and high resolution optical waveguide biosensor based on dense TiO2/Ag multilayer film

    NASA Astrophysics Data System (ADS)

    Jin, Zhao; Guan, Weiming; Liu, Chang; Xue, Tianyu; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

    2016-07-01

    Optical waveguide (OWG) biosensor has attracted much attention according to the high sensitivity and resolution compared with conventional surface plasmon resonance (SPR) biosensor. Nanoporous materials are usually used as the waveguide layer for absorbing analytes into the porous structure and enhancing the sensor signal. However, this kind of waveguide layer provides poor protection to the metal film and leads to the damage of the biosensor. Ag film can provide great sensitivity in SPR sensing comparing to other metal but was rarely used because of its poor chemical stability. Fabricating high stability Ag based SPR biosensor is still a challenge. In this work we produce an OWG biosensor using a dense TiO2 film as the waveguide layer which provides high resolution and remarkable protection to the metal film. This waveguide structure makes long time detection possible using Ag as the metal layer and is able to lead an enhancement of sensitivity comparing to the Au-based biosensor.

  11. Characteristics and anticorrosion performance of Fe-doped TiO2 films by liquid phase deposition method

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Xu, Chao; Feng, ZuDe

    2014-09-01

    Fe-doped TiO2 thin films were fabricated by liquid phase deposition (LPD) method, using Fe(III) nitrate as both Fe element source and fluoride scavenger instead of commonly-used boric acid (H3BO3). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectrum were employed to examine the effects of Fe element on morphology, structure and optical characteristics of TiO2 films. The as-prepared films were served as photoanode applied to photogenerated cathodic protection of SUS304 stainless steel (304SS). It was observed that the photoelectrochemical properties of the as-prepared films were enhanced with the addition of Fe element compared to the undoped TiO2 film. The highest photoactivity was achieved for Ti13Fe (Fe/Ti = 3 molar ratio) film prepared in precursor bath containing 0.02 M TiF4 + 0.06 M Fe(NO3)3 under white-light illumination. The effective anticorrosion behaviors can be attributed to the Fe element incorporation which decreases the probability of photogenerated charge-carrier recombination and extends the light response range of Fe-doped TiO2 films appeared to visible-light region.

  12. Cu-doped TiO(2) nanoparticles enhance survival of Shewanella oneidensis MR-1 under ultraviolet light (UV) exposure.

    PubMed

    Wu, Bing; Zhuang, Wei-Qin; Sahu, Manoranjan; Biswas, Pratim; Tang, Yinjie J

    2011-10-01

    It has been shown that photocatalytic TiO(2) nanoparticles (NPs) can be used as an efficient anti-microbial agent under UV light due to generation of reactive oxygen species (ROS), while Shewanella oneidensis MR-1 is a metal-reducing bacterium highly susceptible to UV radiation. Interestingly, we found that the presence of Cu-doped TiO(2) NPs in the cultural medium dramatically increased the survival rates (based on colony-forming unit) of strain MR-1 by over 10,000-fold (incubation without shaking) and ~200 fold (incubation with shaking) after a 2-h exposure to UV light. Gene expression results (via qPCR measurement) indicated that the DNA repair gene recA in MR-1 was significantly induced by UV exposure (indicating cellular damage under UV stress), but the influence of NPs on recA expression was not statistically evident. Plausible explanations to NP attenuation of UV stresses are: 1. TiO(2) based NPs are capable of scattering and absorbing UV light and thus create a shading effect to protect MR-1 from UV radiation; 2. more importantly, Cu-doped TiO(2) NPs can co-agglomerate with MR-1 to form large flocs that improves cells' survival against the environmental stresses. This study improves our understanding of NP ecological impacts under natural solar radiation and provides useful insights to application of photocatalytic-NPs for bacterial disinfection. PMID:21855961

  13. Characterization of Ni-doped TiO2 thin films deposited by dip-coating technique

    NASA Astrophysics Data System (ADS)

    Kharoubi, Abdelmalek; Bouaza, A.; Benrabah, B.; Ammari, A.; Khiali, A.

    2015-12-01

    Undoped and Ni-doped TiO2 thin films have been prepared by sol-gel dip-coating method on glass and silicon substrates. X-ray diffraction studies show that both TiO2 and Ni-doped TiO2 thin films are of anatase phase with (1 0 1) as preferential orientation. From the UV-visible spectroscopy analysis, all films exhibits a high transparency ~ 80% and shows that the optical band gap decreases from 3.66 to 3.59 eV, which may be related with the phase composition and impurities. Fourier transformed infrared spectroscopy (FTIR) study confirms the presence of Ti-O, Ti=O and O-H bands. Thermal analysis by differential scanning calorimetriy (DSC) shows endothermic reactions between 30 °C and 280 °C and exothermic reactions between 370 °C and 540 °C corresponding to the crystallization of TiO2 in the anatase phase. The Nyquist plots suggests that the equivalent circuit of the films is an RpCp parallel circuit and shows an increase in resistance Rp with increasing the Ni concentration and a decrease in capacity Cp.

  14. Controlling the Al-doping profile and accompanying electrical properties of rutile-phased TiO2 thin films.

    PubMed

    Jeon, Woojin; Rha, Sang Ho; Lee, Woongkyu; Yoo, Yeon Woo; An, Cheol Hyun; Jung, Kwang Hwan; Kim, Seong Keun; Hwang, Cheol Seong

    2014-05-28

    The role of Al dopant in rutile-phased TiO2 films in the evaluation of the mechanism of leakage current reduction in Al-doped TiO2 (ATO) was studied in detail. The leakage current of the ATO film was strongly affected by the Al concentration at the interface between the ATO film and the RuO2 electrode. The conduction band offset of the interface increased with the increase in the Al dopant concentration in the rutile TiO2, which reduced the leakage current in the voltage region pertinent to the next-generation dynamic random access memory application. However, the Al doping in the anatase TiO2 did not notably increase the conduction band offset even with a higher Al concentration. The detailed analyses of the leakage conduction mechanism based on the quantum mechanical transfer-matrix method showed that Schottky emission and Fowler-Nordheim tunneling was the dominant leakage conduction mechanism in the lower and higher voltage regions, respectively. The chemical analyses using X-ray photoelectron spectroscopy corroborated the electrical test results. PMID:24749990

  15. [Characterization and photocatalytic activity of Ni-doped tiO2 nano photocatalysts prepared by low temperature combustion synthesis].

    PubMed

    Liu, Chao; Tang, Xin-Hu; Mo, Ce-Hui; Wang, Jun

    2006-11-01

    Ni-doped TiO2 photocatalysts were prepared by low temperature combustion synthesis and some properties, such as optical absorption, crystal type, grain size distribution and chemistry transformation during temperature rising were characterized by UV-Vis DRS, X-ray diffraction (XRD), laser light dispersion grain size measurement machine and TG-DSC respectively. The photocatalytic activities of the prepared photocatalysts under visible light irradiation were evaluated by monitoring the degradation of methylene blue dye, a probe pollutant. The results indicate that the Ni-doped TiO2 photocatalysts prepared by low temperature combustion synthesis shift the optical absorption threshold to visible light, the band gap of 0.4 Ni-TiO2 (atomic ratio) is 2.3 eV, which corresponds to a 564 nm threshold in the visible light range. The crystal type of photocatalyst is anatase TiO2 and the content of NiTiO3 rise with the increase of Ni dopant. The grain size of photocatalyst distributes from 50 to 150nm, which account for 96.9% of entire quantity. During temperature rising, the TiO2 phase in photocatalyst transforms from amorphous structure to anatase and NiTiO3 crystallites appear at 445.2 degrees C. After 150 min visible light irradiation, 93.9% of methylene blue dye are degraded over 0.4 Ni-TiO2 photocatalyst. The photocatalytic activity of Ni doped TiO2 is higher than that of P25 under identical conditions. PMID:17326417

  16. TiS2 transformation into S-doped and N-doped TiO2 with visible-light catalytic activity

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chen; Chien, Tzu-En; Lai, Po-Chih; Chiang, Yu-Hsien; Li, Kun-Lin; Lin, Jong-Liang

    2015-12-01

    S-doped rutile has been prepared for the first time by hydrothermal reaction of TiS2 in hydrochloric acid at a low temperature (180 °C), with the S atoms in three states of Tisbnd Ssbnd Ti, Tisbnd Ssbnd O and SO4. TiS2 in nitric acid can also be transformed into TiO2, but with mixed phases of anatase and rutile, containing nitrogen atoms at interstitial sites in the form of Tisbnd Osbnd N or Tisbnd Nsbnd O. The Ssbnd TiO2 catalyst shows a better visible-light reactivity toward adsorbed methylene blue (MB) photodegradation and hydroxylation of terephthalic acid with respect to the Nsbnd TiO2. The possible reasons leading to the high photoactivity of the Ssbnd TiO2 are discussed in terms of the incorporated sulfur states.

  17. Carbonate Doping in TiO2 Microsphere: The Key Parameter Influencing Others for Efficient Dye Sensitized Solar Cell.

    PubMed

    Seddigi, Zaki S; Ahmed, Saleh A; Sardar, Samim; Pal, Samir Kumar

    2016-01-01

    Four key parameters namely light trapping, density of light harvesting centre, photoinduced electron injection and electron transport without self-recombination are universally important across all kinds of solar cells. In the present study, we have considered the parameters in the context of a model Dye Sensitized Solar Cell (DSSC). Our experimental studies reveal that carbonate doping of TiO2 mesoporous microspheres (doped MS) makes positive influence to all the above mentioned key parameters responsible for the enhanced solar cell efficiency. A simple method has been employed to synthesize the doped MS for the photoanode of a N719 (ruthenium dye)-based DSSC. A detail electron microscopy has been used to characterize the change in morphology of the MS upon doping. The optical absorption spectrum of the doped MS reveals significant shift of TiO2 (compared to that of the MS without doping) towards maximum solar radiance (~500 nm) and the excellent scattering in the entire absorption band of the sensitizing dye (N719). Finally, and most importantly, for the first time we have demonstrated that the solar cells with doped MS offers better efficiency (7.6%) in light harvesting compared to MS without doping (5.2%) and also reveal minimum self recombination of photoelectrons in the redox chain. PMID:26984765

  18. Carbonate Doping in TiO2 Microsphere: The Key Parameter Influencing Others for Efficient Dye Sensitized Solar Cell

    PubMed Central

    Seddigi, Zaki S.; Ahmed, Saleh A.; Sardar, Samim; Pal, Samir Kumar

    2016-01-01

    Four key parameters namely light trapping, density of light harvesting centre, photoinduced electron injection and electron transport without self-recombination are universally important across all kinds of solar cells. In the present study, we have considered the parameters in the context of a model Dye Sensitized Solar Cell (DSSC). Our experimental studies reveal that carbonate doping of TiO2 mesoporous microspheres (doped MS) makes positive influence to all the above mentioned key parameters responsible for the enhanced solar cell efficiency. A simple method has been employed to synthesize the doped MS for the photoanode of a N719 (ruthenium dye)-based DSSC. A detail electron microscopy has been used to characterize the change in morphology of the MS upon doping. The optical absorption spectrum of the doped MS reveals significant shift of TiO2 (compared to that of the MS without doping) towards maximum solar radiance (~500 nm) and the excellent scattering in the entire absorption band of the sensitizing dye (N719). Finally, and most importantly, for the first time we have demonstrated that the solar cells with doped MS offers better efficiency (7.6%) in light harvesting compared to MS without doping (5.2%) and also reveal minimum self recombination of photoelectrons in the redox chain. PMID:26984765

  19. Carbonate Doping in TiO2 Microsphere: The Key Parameter Influencing Others for Efficient Dye Sensitized Solar Cell

    NASA Astrophysics Data System (ADS)

    Seddigi, Zaki S.; Ahmed, Saleh A.; Sardar, Samim; Pal, Samir Kumar

    2016-03-01

    Four key parameters namely light trapping, density of light harvesting centre, photoinduced electron injection and electron transport without self-recombination are universally important across all kinds of solar cells. In the present study, we have considered the parameters in the context of a model Dye Sensitized Solar Cell (DSSC). Our experimental studies reveal that carbonate doping of TiO2 mesoporous microspheres (doped MS) makes positive influence to all the above mentioned key parameters responsible for the enhanced solar cell efficiency. A simple method has been employed to synthesize the doped MS for the photoanode of a N719 (ruthenium dye)-based DSSC. A detail electron microscopy has been used to characterize the change in morphology of the MS upon doping. The optical absorption spectrum of the doped MS reveals significant shift of TiO2 (compared to that of the MS without doping) towards maximum solar radiance (~500 nm) and the excellent scattering in the entire absorption band of the sensitizing dye (N719). Finally, and most importantly, for the first time we have demonstrated that the solar cells with doped MS offers better efficiency (7.6%) in light harvesting compared to MS without doping (5.2%) and also reveal minimum self recombination of photoelectrons in the redox chain.

  20. Comparative study of carbon dioxide sensing by Sn-doped TiO2 nanoparticles synthesized by microwave-assisted and solid-state diffusion route

    NASA Astrophysics Data System (ADS)

    Nemade, K. R.; Waghuley, S. A.

    2015-04-01

    Gas sensor based on Sn-doped titanium dioxide (TiO2) nanoparticles has been fabricated and evaluated for carbon dioxide (CO2) sensing. The Sn-doped TiO2 nanoparticles were synthesized by microwave-assisted and solid-state diffusion route. The structure and morphology of resulting samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ultraviolet-visible (UV-VIS) spectroscopy was employed to study the optical properties. The weight loss of samples was analyzed through thermo gravimetric analysis (TGA). The Sn-doped TiO2 nanoparticles synthesized through microwave route exhibited good sensing characteristics.

  1. In situ plasmonic Ag nanoparticle anchored TiO2 nanotube arrays as visible-light-driven photocatalysts for enhanced water splitting

    NASA Astrophysics Data System (ADS)

    Ge, Ming-Zheng; Cao, Chun-Yan; Li, Shu-Hui; Tang, Yu-Xin; Wang, Lu-Ning; Qi, Ning; Huang, Jian-Ying; Zhang, Ke-Qin; Al-Deyab, S. S.; Lai, Yue-Kun

    2016-02-01

    An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ >= 420 nm). It was found that the hydrogen production rate of the Ag@TiO2 NTAs prepared with ultrasonication-assisted deposition for 5 min was approximately 15 times higher than that of its pristine TiO2 NTAs counterpart. The highly efficient photocatalytic hydrogen evolution is attributed to the SPR effect of Ag for enhanced visible light absorption and boosting the photogenerated electron-hole separation/transfer. This strategy is promising for the design and construction of high efficiency TiO2 based photocatalysts for solar energy conversion.An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ >= 420 nm

  2. In situ plasmonic Ag nanoparticle anchored TiO2 nanotube arrays as visible-light-driven photocatalysts for enhanced water splitting.

    PubMed

    Ge, Ming-Zheng; Cao, Chun-Yan; Li, Shu-Hui; Tang, Yu-Xin; Wang, Lu-Ning; Qi, Ning; Huang, Jian-Ying; Zhang, Ke-Qin; Al-Deyab, S S; Lai, Yue-Kun

    2016-03-01

    An ultrasonication-assisted in situ deposition strategy was utilised to uniformly decorate plasmonic Ag nanoparticles on vertically aligned TiO2 nanotube arrays (NTAs) to construct a Ag@TiO2 NTA composite. The Ag nanoparticles act as efficient surface plasmon resonance (SPR) photosensitizers to drive photocatalytic water splitting under visible light irradiation. The Ag nanoparticles were uniformly deposited on the surface and inside the highly oriented TiO2 nanotubes. The visible-light-driven hydrogen production activities of silver nanoparticle anchored TiO2 nanotube array photocatalysts were evaluated using methanol as a sacrificial reagent in water under a 500 W Xe lamp with a UV light cutoff filter (λ ≥ 420 nm). It was found that the hydrogen production rate of the Ag@TiO2 NTAs prepared with ultrasonication-assisted deposition for 5 min was approximately 15 times higher than that of its pristine TiO2 NTAs counterpart. The highly efficient photocatalytic hydrogen evolution is attributed to the SPR effect of Ag for enhanced visible light absorption and boosting the photogenerated electron-hole separation/transfer. This strategy is promising for the design and construction of high efficiency TiO2 based photocatalysts for solar energy conversion. PMID:26878901

  3. Optical properties of Ag -TiO 2 nanocermet films prepared by cosputtering and multilayer deposition techniques.

    PubMed

    Dakka, A; Lafait, J; Sella, C; Berthier, S; Abd-Lefdil, M; Martin, J C; Maaza, M

    2000-06-01

    Ag -TiO2 nanocermet thin films, deposited for optical filtering applications by two sputtering techniques, codeposition and multilayer deposition, exhibit surface plasmon absorption in the spectral range 450 -500 nm. The cosputtering technique induces a columnar growth, whereas multilayer deposition produces a more-random distribution of silver inclusions. Both films have large, flat silver grains at the air -cermet interface. An optical double-heterogeneous layer model based on the experimental morphological parameters of the films accounts well for their experimental transmittance, notably for extra absorption near 700 nm, which is attributed to a surface plasmon in the flat silver grains of the surface. PMID:18345199

  4. 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

  5. Microemulsion synthesis of nanosized TiO(2) particles doping with rare-earth and their photocatalytic activity.

    PubMed

    Jian, Zicong; Pu, Yuying; Fang, Jianzhang; Ye, Zhiping

    2010-01-01

    Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO(2) and Ce-TiO(2) particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO(2) with doping TiO(2) , the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%. PMID:20630027

  6. Near-infrared electroluminescence from light-emitting devices based on Nd-doped TiO2/p+-Si heterostructures

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Lv, Chunyan; Zhu, Chen; Li, Si; Ma, Xiangyang; Yang, Deren

    2014-05-01

    We report on near-infrared (NIR) electroluminescence (EL) from the light-emitting devices based on Nd-doped TiO2/p+-Si heterostructures. NIR emissions peaking at ˜910, 1090, and 1370 nm, originated from intra-4f transitions in Nd3+ ions, can be activated by a forward bias voltage as low as ˜5 V. Such NIR EL is triggered by the energy transferred from TiO2 host to Nd3+ ions. It is found that the coexistence of anatase and rutile phases in the TiO2 host enables the device to exhibit pronounced Nd-related EL without concurrent emission from the TiO2 host itself, quite other than the case of existing only anatase phase in TiO2 host. We tentatively suggest that the anatase/rutile interface states play important role in the energy transfer from TiO2 host to Nd3+ ions.

  7. Study on the catalytic activity of vanadium doped TiO2: Anatase-to-rutile phase transition

    NASA Astrophysics Data System (ADS)

    Zhang, Huiming; Bian, He; Zhang, Shiguo

    2016-01-01

    The catalytic activity of vanadium doped TiO2 in the ethylbenzene oxidative dehydrogenation with CO2 was studied experimentally and theoretically. The experimental results showed that the reduction of ethylbenzene conversion and the styrene selectivity was caused by the transition of anatase to rutile phase. Theoretical results showed that the transition of the anatase to rutile phase was mainly caused by vanadium ions and oxygen vacancies.

  8. Comparison of Nb- and Ta-doping of anatase TiO2 for transparent conductor applications

    NASA Astrophysics Data System (ADS)

    Anh Huy, Huynh; Aradi, Bálint; Frauenheim, Thomas; Deák, Peter

    2012-07-01

    Nb- or Ta-doped anatase TiO2 was shown to be a viable candidate for replacing indium-tin-oxide as a transparent conductive oxide. Calculating the electronic structures we find that Ta has the considerably higher solubility and lower optical effective mass of the two dopants. Our calculations also show that a reducing atmosphere is necessary for efficient dopant incorporation, and oxygen vacancies do not necessarily play a role in their activation.

  9. Origin of the visible-light photoactivity of NH3-treated TiO2: Effect of nitrogen doping and oxygen vacancies

    NASA Astrophysics Data System (ADS)

    Chen, Yilin; Cao, Xiaoxin; Lin, Bizhou; Gao, Bifen

    2013-01-01

    N-doped and oxygen-deficient TiO2 photocatalysts were obtained by heating commercial TiO2 in NH3 atmosphere, followed by a postcalcination process. Catalysts were characterized by X-ray diffraction (XRD), N2-sorption BET surface area, X-ray photoelectron spectroscopy (XPS), Elemental analysis (EA), UV/vis diffuse reflectance spectroscopy (DRS), Electron spin resonance (ESR) and Photoluminescence (PL). It shows that the NH3-heat-treatment of TiO2 resulted in not only nitrogen doping but also creation of oxygen vacancies with optical absorption in visible-light region. The postcalcination achieved several beneficial effects including dramatic removal of surface amino species, a rapid decrease in surface Ti3+ species, and a low recombination rate of photogenerated carriers on the co-doped TiO2. The photocatalytic measurement was carried out by the degradation of gas-phase benzene under visible light irradiation. At steady state, the photocatalytic conversion rate of benzene over the postannealed catalyst was 35.8%, accompanied by the yield of 115 ppmv CO2, which was much higher than that on the NH3-treated TiO2 before postcalcination or the H2-treated TiO2 catalysts. Results show that the visible-light activity of the NH3-treated TiO2 is attributed to a synergistic effect of substitutional nitrogen species and oxygen vacancies in TiO2.

  10. Tungsten Doped TiO2 with Enhanced Photocatalytic and Optoelectrical Properties via Aerosol Assisted Chemical Vapor Deposition

    PubMed Central

    Sathasivam, Sanjayan; Bhachu, Davinder S.; Lu, Yao; Chadwick, Nicholas; Althabaiti, Shaeel A.; Alyoubi, Abdulrahman O.; Basahel, Sulaiman N.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-01-01

    Tungsten doped titanium dioxide films with both transparent conducting oxide (TCO) and photocatalytic properties were produced via aerosol-assisted chemical vapor deposition of titanium ethoxide and dopant concentrations of tungsten ethoxide at 500 °C from a toluene solution. The films were anatase TiO2, with good n-type electrical conductivities as determined via Hall effect measurements. The film doped with 2.25 at.% W showed the lowest resistivity at 0.034 Ω.cm and respectable charge carrier mobility (14.9 cm3/V.s) and concentration (×1019 cm−3). XPS indicated the presence of both W6+ and W4+ in the TiO2 matrix, with the substitutional doping of W4+ inducing an expansion of the anatase unit cell as determined by XRD. The films also showed good photocatalytic activity under UV-light illumination, with degradation of resazurin redox dye at a higher rate than with undoped TiO2. PMID:26042724

  11. Enhancement of Photo-Oxidation Activities Depending on Structural Distortion of Fe-Doped TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kim, Yeonwoo; Yang, Sena; Jeon, Eun Hee; Baik, Jaeyoon; Kim, Namdong; Kim, Hyun Sung; Lee, Hangil

    2016-01-01

    To design a high-performance photocatalytic system with TiO2, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO2 nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO2 nanoparticles (Fe@TiO2) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe2Ti3O9, indicating numerous Ti3+ and oxygen-vacancy sites. The Ti3+ sites act as electron trap sites to deliver the electron to O2 as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (-SH) of 2-aminothiophenol to sulfonic acid (-SO3H) under ultraviolet and visible light illumination.

  12. Synthesis, characterization and photocatalytic study of graphene oxide and cerium co-doped in TiO2

    NASA Astrophysics Data System (ADS)

    Li, Jia; Zhang, Quan; Zeng, Liping; He, Deliang

    2016-02-01

    The nanocomposite of titanium dioxide (TiO2) combined with graphene oxide (GO) and cerium (Ce) was successfully synthesized via sol-gel method followed by calcining at 300 °C for 2 h. The composite was characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM) and Brunauer-Emmett-Teller. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) under the irradiation of xenon lamp. This study demonstrated that GO and Ce co-doped in TiO2 could broaden absorption edge to the visible light and increase surface area of samples. SEM observation showed that addition of Ce could solve the problem of the agglomeration of GO under the same experimental conditions. Moreover, the MB photocatalytic degradation rate of the composite with GO doped for 0.2 % and Ce doped for 0.6 % (mass ratio) was up to 97.7 %, which was largely attributed to the synergistic effects in the GO, Ce and TiO2 system.

  13. Preparation of N-doped TiO2 by oxidizing TiN and its application on phenol degradation.

    PubMed

    Huang, Ji-Guo; Zhao, Xiao-Guang; Zheng, Meng-Yang; Li, Sen; Wang, Yu; Liu, Xing-Juan

    2013-01-01

    Incomplete oxidation of titanium nitride (TiN) to prepare nitrogen-doped TiO2 was verified by calcining TiN at different temperatures in air for 30 min. The as-prepared samples were characterized by X-ray diffraction, UV-Vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results confirmed that oxidizing TiN incompletely is an effective and simple method to prepare nitrogen-doped TiO2. Photocatalytic degradation of phenol was conducted to evaluate the photocatalytic activity of as-prepared samples. The results showed that phenol can be degraded efficiently by the as-prepared samples under visible light; low phenol concentration was conducive to degradation; the optimum calcination temperature and photocatalyst dosage are 650 °C and 0.5 g/L, respectively. The effects of different light sources on phenol degradation were compared. The reusability of nitrogen-doped TiO2 was tested and the results indicated a relatively good reusability under laboratory conditions. PMID:23985527

  14. Enhancement of Photo-Oxidation Activities Depending on Structural Distortion of Fe-Doped TiO2 Nanoparticles.

    PubMed

    Kim, Yeonwoo; Yang, Sena; Jeon, Eun Hee; Baik, Jaeyoon; Kim, Namdong; Kim, Hyun Sung; Lee, Hangil

    2016-12-01

    To design a high-performance photocatalytic system with TiO2, it is necessary to reduce the bandgap and enhance the absorption efficiency. The reduction of the bandgap to the visible range was investigated with reference to the surface distortion of anatase TiO2 nanoparticles induced by varying Fe doping concentrations. Fe-doped TiO2 nanoparticles (Fe@TiO2) were synthesized by a hydrothermal method and analyzed by various surface analysis techniques such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, scanning transmission X-ray microscopy, and high-resolution photoemission spectroscopy. We observed that Fe doping over 5 wt.% gave rise to a distorted structure, i.e., Fe2Ti3O9, indicating numerous Ti(3+) and oxygen-vacancy sites. The Ti(3+) sites act as electron trap sites to deliver the electron to O2 as well as introduce the dopant level inside the bandgap, resulting in a significant increase in the photocatalytic oxidation reaction of thiol (-SH) of 2-aminothiophenol to sulfonic acid (-SO3H) under ultraviolet and visible light illumination. PMID:26822520

  15. Tungsten Doped TiO2 with Enhanced Photocatalytic and Optoelectrical Properties via Aerosol Assisted Chemical Vapor Deposition.

    PubMed

    Sathasivam, Sanjayan; Bhachu, Davinder S; Lu, Yao; Chadwick, Nicholas; Althabaiti, Shaeel A; Alyoubi, Abdulrahman O; Basahel, Sulaiman N; Carmalt, Claire J; Parkin, Ivan P

    2015-01-01

    Tungsten doped titanium dioxide films with both transparent conducting oxide (TCO) and photocatalytic properties were produced via aerosol-assisted chemical vapor deposition of titanium ethoxide and dopant concentrations of tungsten ethoxide at 500 °C from a toluene solution. The films were anatase TiO2, with good n-type electrical conductivities as determined via Hall effect measurements. The film doped with 2.25 at.% W showed the lowest resistivity at 0.034 Ω.cm and respectable charge carrier mobility (14.9 cm(3)/V.s) and concentration (×10(19) cm(-3)). XPS indicated the presence of both W(6+) and W(4+) in the TiO2 matrix, with the substitutional doping of W(4+) inducing an expansion of the anatase unit cell as determined by XRD. The films also showed good photocatalytic activity under UV-light illumination, with degradation of resazurin redox dye at a higher rate than with undoped TiO2. PMID:26042724

  16. Fabrication of N-doped TiO2 coatings on nanoporous Si nanopillar arrays through biomimetic layer by layer mineralization.

    PubMed

    Yan, Yong; Wang, Dong; Schaaf, Peter

    2014-06-14

    Si/N-doped TiO2 core/shell nanopillar arrays with a nanoporous structure are fabricated through a simple protein-mediated TiO2 deposition process. The Si nanopillar arrays are used as templates and alternatively immersed in aqueous solutions of catalytic molecules (protamine, PA) and the titania precursor (titanium(iv) bis(ammonium lactato)dihydroxide, Ti-BALDH) for the layer by layer mineralization of a PA/TiO2 coating. After a subsequent calcination, a N-doped TiO2 layer is formed, and its thickness could be controlled by varying the cycles of deposition. Moreover, the nanoporous structure of the Si nanopillars strongly affects the formation of the TiO2 layer. The obtained Si/TiO2 nanocomposites show significantly improved solar absorption compared with commercially purchased TiO2 nanoparticles. PMID:24754039

  17. Kinetics stabilized doping: computational optimization of carbon-doped anatase TiO2 for visible-light driven water splitting.

    PubMed

    Sun, Yi-Yang; Zhang, Shengbai

    2016-01-28

    Using density functional theory calculation we investigate the carbon doping of anatase TiO2, a technique widely studied for visible-light driven water splitting. By a detailed analysis of the thermodynamics of C defects in TiO2, we show that any significant concentration of C dopants in the TiO2 lattice must be a result of non-equilibrium doping, which emphasizes the importance of kinetics stabilized C defects. Based on the band gaps calculated using hybrid density functionals, we exclude the possibility of C occupying Ti lattice sites or interstitial sites to enhance visible-light absorption of TiO2, as extensively discussed in the literature. Also, the recently proposed defect with a CO species occupying two O sites yields a too small band gap for water splitting. Two defects that can effectively reduce the band gap for the water splitting application are identified to be: (1) the CO-VO complex, i.e., a C substituting for O (CO) paired with an O vacancy (VO) and (2) the (C2)2O complex with a C dimer (C2) occupying two neighboring O vacancies. Compared with the CO-VO complex, (C2)2O exhibits strong binding (greater than 2.5 eV) between the two C atoms, which could significantly enhance its kinetic stability to survive from high temperature annealing. With a reduced band gap of about 1.4 eV, carbon dimers could be ideal for kinetic doping of anatase TiO2 to enhance its visible-light activity in photocatalytic reactions. Molecular doping using C2H2 or C2H4 as C precursors has been proposed to introduce the carbon dimers into TiO2. PMID:26725589

  18. Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

    NASA Astrophysics Data System (ADS)

    Ahamed, Maqusood; Khan, M. A. Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws

    2016-07-01

    We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells.

  19. Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells.

    PubMed

    Ahamed, Maqusood; Khan, M A Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A; Alshamsan, Aws

    2016-01-01

    We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1-10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV-3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation &glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells. PMID:27444578

  20. Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

    PubMed Central

    Ahamed, Maqusood; Khan, M. A. Majeed; Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws

    2016-01-01

    We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells. PMID:27444578

  1. Nitrogen-Doped Ordered Mesoporous Anatase TiO2 Nanofibers as Anode Materials for High Performance Sodium-Ion Batteries.

    PubMed

    Wu, Ying; Liu, Xiaowu; Yang, Zhenzhong; Gu, Lin; Yu, Yan

    2016-07-01

    Nitrogen-doped ordered mesoporous TiO2 nanofibers (N-MTO) have been fabricated by electrospinning and subsequent nitridation treatment. The N-doping in TiO2 leads to the formation of Ti(3+) , resulting in the improved electron conductivity of TiO2 . In addition, one-dimensional (1D) N-MTO nanostructure possesses very short diffusion length of Na(+) /e(-) in N-MTO, easy access of electrolyte, and high conductivity transport of electrons along the percolating fibers. The N-MTO shows excellent sodium storage performance. PMID:27185585

  2. Energy Storage: Nitrogen-Doped Ordered Mesoporous Anatase TiO2 Nanofibers as Anode Materials for High Performance Sodium-Ion Batteries (Small 26/2016).

    PubMed

    Wu, Ying; Liu, Xiaowu; Yang, Zhenzhong; Gu, Lin; Yu, Yan

    2016-07-01

    On page 3522, Y. Yu and co-workers fabricate nitrogen-doped ordered mesoporous TiO2 nanofibers (denoted as N-MTO) by electrospinning and subsequent nitridation treatment. Nitrogen atoms are successfully doped into the TiO2 lattice, accompanied by the formation of Ti(3+) and oxygen vacancies, contributing to the improvement of electronic conductivity of TiO2 . When used as an anode for a sodium-ion battery, the N-MTO demonstrates excellent rate capability and superior long cycling performance. PMID:27383035

  3. Solvothermal synthesis of carbon coated N-doped TiO2 nanostructures with enhanced visible light catalytic activity

    NASA Astrophysics Data System (ADS)

    Yan, Xue-Min; Kang, Jialing; Gao, Lin; Xiong, Lin; Mei, Ping

    2013-01-01

    Visible light-active carbon coated N-doped TiO2 nanostructures(CTS-TiO2) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180 °C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The CTS-TiO2 nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5-7 nm. A wormhole mesostructure can be observed in the CTS-TiO2 nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO2. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at λ ≥ 400 nm. The results show that CTS-TiO2 nanostructures display a higher visible light photocatalytic activity than pure TiO2, commercial P25 and C-coated TiO2 (C-TiO2) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons and holes by carbon modification.

  4. Synthesis of C-N-Y tri-doped TiO2 photo-catalyst for MO degradation and characterization

    NASA Astrophysics Data System (ADS)

    Hoseinian-Maleki, F.; Nemati, A.; Joya, Yasir F.

    2015-10-01

    In this research C-N-Y tri-doped TiO2 nanopowders were synthesized by the sol-gel method. The C-N-Y TiO2 photo-catalyst was prepared using hexamine and yttrium nitrate Hexahydrate as the dopant precursors. Methyl-orange (MO) was used to study the photocatalytic performance of the doped TiO2 under UV irradiation. The synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, Transmission electron microscopy, Photoluminescence and Field emission scanning electron microscopy. The tri-doped sample with 8% N, 0.4% Y and 1.5% C exhibited enhanced photocatalytic efficiencies. After 100 min of irradiation with UV light, 87% of MO was decomposed by C-N-Y tri-doped TiO2 sample. It is suggested that the co-activity of C and N could make the intra-gap localized states above the valence band of TiO2, and carbon in TiO2 structure causes carbonate species to appear. These carbonate species acted as photosensitizer on the TiO2 surface to promote photo-catalytic activity of the as synthesized sample.

  5. 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

  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. Efficiency enhancement of dye-sensitized solar cells by use of ZrO2-doped TiO2 nanofibers photoanode.

    PubMed

    Mohamed, Ibrahim M A; Dao, Van-Duong; Barakat, Nasser A M; Yasin, Ahmed S; Yousef, Ahmed; Choi, Ho-Suk

    2016-08-15

    Due to the good stability and convenient optical properties, TiO2 nanostructures still the prominent photoanode materials in the Dye Sensitized Solar Cells (DSCs). However, the well-known low bandgap energy and weak adsorption affinity for the dye distinctly constrain the wide application. This work discusses the impact of Zr-doping and nanofibrous morphology on the performance and physicochemical properties of TiO2. Zr-doped TiO2 nanofibers (NFs), with various zirconia content (0, 0.5, 1, 1.5 and 2wt%) were prepared by calcination of electrospun mats composed of polyvinyl acetate, titanium isopropoxyl and zirconium n-propoxyl. For all formulations, the results have shown that the prepared materials are continuous, randomly oriented, and good morphology nanofibers. The average diameter decreased from 353.85nm to 210.78nm after calcination without a considerable influence on the nanofibrous structure regardless the zirconia content. XRD result shows that there is no Rutile nor Brookite phases in the obtained material and the average crystallite size of the sample is affected by the presence of Zr-doping and changed from 23.01nm to 37.63nm for TiO2 and Zr-doped TiO2, respectively. Optical studies have shown Zr-doped TiO2 NFs have more absorbance in the visible region than that of pristine TiO2 NFs; the maximum absorbance is corresponding to the NFs having 1wt% zirconia. The improved spectra of Zr-doped TiO2 in the visible region is attributed to the heterostructure composition resulting from Zr-doping. The absorption bandgaps were calculated using Tauc model as 3.202 and 3.217 for pristine and Zr (1wt%)-doped TiO2 NFs, respectively. Furthermore, in Dye-sensitized Solar Cells, utilizing Zr (1wt%)-doped TiO2 nanofibers achieved higher efficiency of 4.51% compared to the 1.61% obtained from the pristine TiO2 NFs. PMID:27179174

  8. 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

  9. Capacitive and oxidant generating properties of black-colored TiO2 nanotube array fabricated by electrochemical self-doping.

    PubMed

    Kim, Choonsoo; Kim, Seonghwan; Lee, Jaehan; Kim, Jiye; Yoon, Jeyong

    2015-04-15

    Recently, black-colored TiO2 NTA (denoted as black TiO2 NTA) fabricated by self-doping of TiO2 NTA with the amorphous phase led to significant success as a visible-light-active photocatalyst. This enhanced photocatalytic activity is largely attributed to a higher charge carrier density as an effect of electrochemical self-doping resulting in a higher optical absorbance and lower transport resistance. Nevertheless, the potential of black TiO2 NTA for other electrochemical applications, such as a supercapacitor and an oxidant-generating anode, has not been fully investigated. Here, we report the capacitive and oxidant generating properties of black TiO2 NTA. The black TiO2 NTA exhibited significantly a high value for areal capacitance with a good rate capability and novel electrocatalytic activity in generating (•)OHs and Cl2 compared to pristine TiO2 NTA with the anatase phase. This study suggests that the black TiO2 NTA be applied as a supercapacitor and an oxidant generating anode. PMID:25793300

  10. Improvement of Charge Transportation in Si Quantum Dot-Sensitized Solar Cells Using Vanadium Doped TiO2.

    PubMed

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

    2016-05-01

    The multiple exciton generation characteristics of quantum dots have been expected to enhance the performance of photochemical solar cells. In previous work, we first introduced Si quantum dot for sensitized solar cells. The Si quantum dots were fabricated by multi-hollow discharge plasma chemical vapor deposition, and were characterized optically and morphologically. The Si quantum dot-sensitized solar cells had poor performance due to significant electron loss by charge recombination. Although the large Si particle size resulted in the exposure of a large TiO2 surface area, there was a limit to ho much the particle size could be decreased due to the reduced absorbance of small particles. Therefore, this work focused on decreasing the internal impedance to improve charge transfer. TiO2 was electronically modified by doping with vanadium, which can improve electron transfer in the TiO2 network, and which is stable in the redox electrolyte. Photogenerated electrons can more easily arrive at the conductive electrode due to the decreased internal impedance. The dark photovoltaic properties confirmed the reduction of charge recombination, and the photon-to-current conversion efficiency reflected the improved electron transfer. Impedance analysis confirmed a decrease in internal impedance and an increased electron lifetime. Consequently, these improvements by vanadium doping enhanced the overall performance of Si quantum dot-sensitized solar cells. PMID:27483838

  11. Photocatalytic degradation of 17α-ethinylestradiol (EE2) in the presence of TiO2-doped zeolite.

    PubMed

    Pan, Zhong; Stemmler, Elizabeth A; Cho, Hong Je; Fan, Wei; LeBlanc, Lawrence A; Patterson, Howard H; Amirbahman, Aria

    2014-08-30

    Current design limitations and ineffective remediation techniques in wastewater treatment plants have led to concerns about the prevalence of pharmaceutical and personal care products (PPCPs) in receiving waters. A novel photocatalyst, TiO2-doped low-silica X zeolite (TiO2-LSX), was used to study the degradation of the pharmaceutical compound, 17α-ethinylestradiol (EE2). The catalyst was synthesized and characterized using XRD, BET surface analysis, SEM-EDAX, and ICP-OES. The effects of different UV light intensities, initial EE2 concentrations, and catalyst dosages on the EE2 removal efficiency were studied. A higher EE2 removal efficiency was attained with UV-TiO2-LSX when compared with UV-TiO2 or UV alone. The EE2 degradation process followed pseudo-first-order kinetics. A comprehensive empirical model was developed to describe the EE2 degradation kinetics under different conditions using multiple linear regression analysis. The EE2 degradation mechanism was proposed based on molecular calculations, identification of photoproducts using HPLC-MS/MS, and reactive species quenching experiments; the results showed that oxidative degradation pathways initiated by hydroxyl radicals were predominant. This novel TiO2-doped zeolite system provides a promising application for the UV disinfection process in wastewater treatment plants. PMID:25036996

  12. Efficient Mineralization of Toluene by W-Doped TiO2 Nanofibers Under Visible Light Irradiation.

    PubMed

    Zhang, Li; Li, Yaogang; Xie, Hongyong; Wang, Hongzhi; Zhang, Qinghong

    2015-04-01

    Toxic toluene gas caused enormous harm to human health, and the traditional method to deal with this puzzle is using physical adsorption, which just transfer the toluene from one medium to another. Photocatalysis has great potential to mineralize toluene into CO2 under visible light irradiation, but their applications have been limited by difficulties in preparing efficient photocatalysts with fine crystallite size, considerable visible light response, and large surface area to contact with toluene gas. To address this problem, we have developed a film composed of W-doped TiO2 nanofibers to mineralize toluene under visible light irradiation. The electrospinning preparation route allows incorporation of up to 50 wt% of W in substitutional positions of titanium atom in the anatase network. The W-doped TiO2 nanofibers behave finer crystallite size, stronger visible light absorbance, and larger surface area comparing with pure TiO2 nanofibers. The nanofiber structured morphology on the quartz tube promotes the reaction rates for the gas-phase photo-oxidation of toluene. The concentrations of the produced CO2 keep steady during the photodegradation process, indicating the practicality and operability for the whole experiment. This research is conducive to the development of novel photocatalytic materials to efficiently mineralize toxic gas pollutants including toluene for practical application. PMID:26353518

  13. Migration of Ag- and TiO2-(Nano)particles from textiles into artificial sweat under physical stress: experiments and exposure modeling.

    PubMed

    von Goetz, N; Lorenz, C; Windler, L; Nowack, B; Heuberger, M; Hungerbühler, K

    2013-09-01

    Engineered nanoparticles (ENP) are increasingly used to functionalize textiles taking advantage, e.g., of the antimicrobial activity of silver (Ag)-ENP or the UV-absorption of titania (TiO2)-ENP. Mobilization and migration of ENPs from the textile into human sweat can result in dermal exposure to these nanoobjects and their aggregates and agglomerates (NOAA). In this study we assessed exposure to NOAA migrating from commercially available textiles to artificial sweat by an experimental setup that simulates wear-and-tear during physical activity. By combining physical stress with incubation in alkaline and acidic artificial sweat solutions we experimentally realized a worst case scenario for wearing functionalized textiles during sports activities. This experimental approach is not limited to NOAA, but can be used for any other textile additive. Out of four investigated textiles, one T-shirt and one pair of trousers with claimed antimicrobial properties were found to release Ag <450 nm in detectable amounts (23-74 μg/g/L). Textiles containing TiO2 for UV protection did not release significant amounts of TiO2 <450 nm, but the antimicrobial T-shirt released both TiO2 and Ag <450 nm. The silver was present in dissolved and particulate form, whereas TiO2 was mainly found as particulate. On the basis of our experimental results we calculated external dermal exposure to Ag and TiO2 for male and female adults per use. For silver, maximal amounts of 17.1 and 8.2 μg/kg body weight were calculated for total and particulate Ag <450 nm, respectively. For TiO2, the exposure levels amount to maximal 11.6 μg/kg body weight for total (mainly particulate) TiO2. In comparison with other human exposure pathways, dermal exposure to NOAA from textiles can be considered comparably minor for TiO2-NOAA, but not for Ag-NOAA. PMID:23786648

  14. Transparent conductive Nb-doped TiO2 films deposited by RF magnetron co-sputtering

    NASA Astrophysics Data System (ADS)

    Wan, Guangmiao; Wang, Shenwei; Zhang, Xinwu; Huang, Miaoling; Zhang, Yanwei; Duan, Wubiao; Yi, Lixin

    2015-12-01

    In this work, Nb-doped TiO2 films were deposited on glass substrates utilizing RF magnetron co-sputtering with a TiO2 target and a Nb target. In order to study the effect of Nb concentration, four groups of films with different Nb concentration were prepared and annealed in N2 at 500 °C. Crystal structure, surface morphology, electrical and optical property of the films were characterized. The lowest resistivity was measured to be 1.2 × 10-3 Ω cm at the Nb concentration of 7.0 at.%. Meanwhile, Hall mobility and carrier density were 2.0 cm2/Vs and 2.6 × 1021 cm-3, respectively.

  15. TiO2-doped MoO3 electrochromic thin films via sol-gel method

    NASA Astrophysics Data System (ADS)

    Wang, Zhongchun; Chen, Xiaofeng; Hu, Xingfang

    1998-02-01

    MoO3 films allow high intercalation rate, but deintercalation is difficult to perform. It is the reason the MoO3 film has lower response time for use as electrochromic display materials. The effect of additive on the electrochromic property of MoO3 thin films produced by sol-gel method has been studied. The pure and TiO2-doped MoO3 thin films were characterized optically and electrochemically in LiClO4-propylene carbonate solutions. The experimental results showed that the additive of TiO2 had improved remarkably the cyclic stability and reversibility of the MoO3 film electrochromic electrode.

  16. Disinfection of Escherichia coli Gram negative bacteria using surface modified TiO2: optimization of Ag metallization and depiction of charge transfer mechanism.

    PubMed

    Gomathi Devi, LakshmipathiNaik; Nagaraj, Basavalingaiah

    2014-01-01

    The antibacterial activity of silver deposited TiO2 (Ag-TiO2 ) against Gram negative Escherichia coli bacteria was investigated by varying the Ag metal content from 0.10 to 0.50% on the surface of TiO2 . Ag depositions by the photoreduction method were found to be stable. Surface silver metallization was confirmed by EDAX and XPS studies. Photoluminescence studies show that the charge carrier recombination is less for 0.1% Ag-TiO2 and this catalyst shows superior bactericidal activity under solar light irradiation compared to Sol gel TiO2 (SG-TiO2 ) due to the surface plasmon effect. The energy levels of deposited Ag are dependent on the Ag content and it varies from -4.64 eV to -1.30 eV with respect to the vacuum energy level based on atomic silver to bulk silver deposits. The ability of electron transfer from Ag deposit to O2 depends on the position of the energy levels. The 0.25% and 0.50% Ag depositions showed detrimental effect on bactericidal activity due to the mismatch of energy levels. The effect of the EROS (External generation of the Reactive Oxygen Species by 0.1% Ag-TiO2 ) and IROS (Interior generation of Reactive Oxygen Species within the bacteria) on the bactericidal inactivation is discussed in detail. PMID:24995499

  17. Highly oriented and physical properties of sprayed anatase Sn-doped TiO2 thin films with an enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Dhanapandian, S.; Arunachalam, A.; Manoharan, C.

    2016-03-01

    Pristine TiO2 and Sn-doped TiO2 thin films with different Sn doping levels (2, 4, 6 and 8 at.%) were deposited by employing a simplified spray pyrolysis technique. The XRD pattern of the films confirmed tetragonal structure with the polycrystalline nature. The films exhibited a pure anatase titanium dioxide (TiO2) with a strong orientation along (101) plane. The scanning electron microscopy image of 6 at.% Sn-doped TiO2 thin film depicted nanosized grains with porous nature. The atomic force microscopy study had shown the columnar arrangement of grains with the increase in particle size and surface roughness for 6 at.% Sn-doped TiO2 thin films. The optical transmittance was increased with the decrease in the optical energy band gap. The optical constants such as extinction coefficient and refractive index were determined. The intensity of the photoluminescence emission was observed at 398 nm for doped films. The resistivity decreased with the increasing carrier concentration and Hall mobility. The incorporation of Sn into TiO2 matrix yielded a well-pronounced antibacterial activity for Bacillus subtilis.

  18. Photocatalytic performance of nitrogen, osmium co-doped TiO2 for removal of eosin yellow in water under simulated solar radiation.

    PubMed

    Kuvarega, Alex T; Krause, Rui W M; Mamba, Bhekie B

    2013-07-01

    Nitrogen, osmium co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using ammonia as the nitrogen source and osmium tetroxide as the source of osmium. The role of rutile phase OsO2 in enhancing the photocatalytic activity of rutile TiO2 towards the degradation of Eosin Yellow was investigated. The materials were characterised by various techniques that include FTIR, Raman, XRD, SEM, EDS, TEM, TGA and DRUV-Vis. The amorphous, oven dried sample was transformed to the anatase and then the rutile phase with increasing calcination temperature. DRUV-Vis analysis revealed a red shift in absorption with increasing calcination temperature, confirmed by a decrease in the band gap of the material. The photocatalytic activity of N, Os co-doped TiO2 was evaluated using eosin yellow degradation and activity increased with increase in calcination temperature under simulated solar irradiation. The rutile phase of the co-doped TiO2 was found to be more effective in degrading the dye (k(a) = 1.84 x 10(-2) min(-1)) compared to the anatase co-doped phase (k(a) = 9.90 x 10(-3) min(-1)). The enhanced photocatalytic activity was ascribed to the synergistic effects of rutile TiO2 and rutile OsO2 in the N, Os co-doped TiO2. PMID:23901525

  19. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    PubMed

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH). PMID:26716202

  20. First-principle study of the electronic structure and optical property of Nb-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Hou, Q. Y.; Liu, Q. L.; Zhao, C. W.; Zhang, Y.

    2014-04-01

    The absorption edge shifted to long wavelength direction and short wavelength direction of two opposite experimental conclusions have been reported, when the band-gap and absorption spectra of Nb-doped anatase TiO2 were studied. In order to solve this contradiction, the electronic structure and the optical property of Nb heavy doped anatase TiO2 have been studied by the first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory with +U method modification. The calculated results indicate that the higher the Nb-doping is, the higher the total energy is, the worse the stability is, the higher the formation energy is, the more difficult the doping is, the wider the optical band-gap is, the more obvious the absorption edge shifting to short wavelength direction is, the lower the absorptivity and the reflectivity is, which is in agreement with the experimental results. The reasonable interpretation of the contradiction has been reported in this paper, too.

  1. Raman spectroscopic investigation on TiO2-N719 dye interfaces using Ag@TiO2 nanoparticles and potential correlation strategies.

    PubMed

    Qiu, Zhi; Zhang, Meng; Wu, De-Yin; Ding, Song-Yuan; Zuo, Qi-Qi; Huang, Yi-Fan; Shen, Wei; Lin, Xiao-Dong; Tian, Zhong-Qun; Mao, Bing-Wei

    2013-07-22

    Herein, we employ Ag@TiO2 core-shell nanoparticles for surface-enhanced Raman scattering (SERS) investigations of TiO2-N719 dye interfaces. In situ electrochemical SERS investigations of the Ag@TiO2-N719 interaction are systematically carried out under a series of electrode-potential controls. By comparing the potential dependence of resonant and pre-resonant SERS spectra recorded with different laser excitations, bidentate carboxylate linkage is considered to be involved in N719 adsorption on TiO2. Meanwhile, SCN ligand shows obvious interactions with TiO2, and their role in the adsorption and orientation of N719 on TiO2 should not be underestimated. The in situ SERS spectra of Ag@TiO2 show a clear bell-shaped intensity-potential relation for the major bands of N719. A molecule-to-TiO2 charge-transfer resonance is tentatively attributed to account for such a phenomenon. Under the influence of such a charge-transfer resonance, valuable information about the N719-TiO2 interaction as well as the intramolecular deformation of N719 is obtained. PMID:23824871

  2. Physical properties of Zn doped TiO2 thin films with spray pyrolysis technique and its effects in antibacterial activity.

    PubMed

    Arunachalam, A; Dhanapandian, S; Manoharan, C; Sivakumar, G

    2015-03-01

    Zinc doped Titanium dioxide (TiO2: Zn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 450°C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (101) plane at 8at.% of Zn-doped TiO2 film. Scanning electron microscopy (SEM) study showed the uniform distribution of grains with porous nature. Atomic force microscopy (AFM) observations indicated the tetragonal shape at 8at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398nm was observed at the 8at.% of Zn-doped TiO2 thin film. The carrier concentration and Hall mobility was increased with doping. The antibacterial activity was highly yielded for the Zn-doped TiO2 thin films. PMID:25479105

  3. Design of Ag@C@SnO2@TiO2 yolk-shell nanospheres with enhanced photoelectric properties for dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhao, Peilu; Li, Dan; Yao, Shiting; Zhang, Yiqun; Liu, Fengmin; Sun, Peng; Chuai, Xiaohong; Gao, Yuan; Lu, Geyu

    2016-06-01

    The hierarchical Ag@C@SnO2@TiO2 nanospheres (ACSTS) have been successfully synthesized by deposition of SnO2 and TiO2 on the Ag@C templates layer by layer. The size of ACSTS is ca. 360 nm while the Ag@C cores have an average diameter of about 300 nm. The rough and porous shell structure consisting of SnO2 and TiO2 ensures a large specific surface area (115.5 m2 g-1). To demonstrate how such a unique structure might lead to more excellent photovoltaic property, several kinds of dye-sensitized solar cells (DSSCs) are also fabricated using different nanospheres based photoanodes. It is found that the ACSTS based DSSC exhibits an obvious improvement in cell performance. According to various technical characterization, the ACSTS can provide dual-functions of light absorption and charge transfer, hence resulting in an enhanced short-circuit photocurrent density of 18.68 mA cm-2 and a higher FF of 63% compared with other DSSCs. The ACSTS cell finally obtains a PCE of up to 8.62%, increasing by 70.4% and 10.2% than hollow TiO2 nanospheres and Ag@C@TiO2 nanospheres based cells, respectively. The improved photovoltaic properties of ACSTS cell can be mainly ascribed to the unique microstructure and the synergistic effect of the encapsulated Ag@C cores.

  4. Interfacial n-Doping Using an Ultrathin TiO2 Layer for Contact Resistance Reduction in MoS2.

    PubMed

    Kaushik, Naveen; Karmakar, Debjani; Nipane, Ankur; Karande, Shruti; Lodha, Saurabh

    2016-01-13

    We demonstrate a low and constant effective Schottky barrier height (ΦB ∼ 40 meV) irrespective of the metal work function by introducing an ultrathin TiO2 ALD interfacial layer between various metals (Ti, Ni, Au, and Pd) and MoS2. Transmission line method devices with and without the contact TiO2 interfacial layer on the same MoS2 flake demonstrate reduced (24×) contact resistance (RC) in the presence of TiO2. The insertion of TiO2 at the source-drain contact interface results in significant improvement in the on-current and field effect mobility (up to 10×). The reduction in RC and ΦB has been explained through interfacial doping of MoS2 and validated by first-principles calculations, which indicate metallic behavior of the TiO2-MoS2 interface. Consistent with DFT results of interfacial doping, X-ray photoelectron spectroscopy (XPS) data also exhibit a 0.5 eV shift toward higher binding energies for Mo 3d and S 2p peaks in the presence of TiO2, indicating Fermi level movement toward the conduction band (n-type doping). Ultraviolet photoelectron spectroscopy (UPS) further corroborates the interfacial doping model, as MoS2 flakes capped with ultrathin TiO2 exhibit a reduction of 0.3 eV in the effective work function. Finally, a systematic comparison of the impact of selective doping with the TiO2 layer under the source-drain metal relative to that on top of the MoS2 channel shows a larger benefit for transistor performance from the reduction in source-drain contact resistance. PMID:26649572

  5. Enhanced ionic conductivity in polycrystalline TiO2 by "one-dimensional doping".

    PubMed

    Adepalli, Kiran Kumar; Kelsch, Marion; Merkle, Rotraut; Maier, Joachim

    2014-03-14

    The influence of line defects (dislocations) on the electrical properties of polycrystalline TiO2 was investigated. Line defects were created in TiO2 during spark plasma sintering at 1000 °C and 400 MPa. TEM characterisation indicates dislocations to be preferably oriented on {110} and {101} planes. The measured electrical conductivity as a function of oxygen partial pressure and temperature revealed that the dislocations play a vital role in modifying the defect chemistry of TiO2. The presence of dislocations enhanced the ionic conductivity over a wide range of oxygen partial pressures. The observed changes can be interpreted in terms of negatively charged dislocation cores and adjacent space charge accumulation layers. The present findings point towards an alternative method to tune the electrical properties of ionic solids. PMID:24477488

  6. Effect of Ce doping of TiO2 support on NH3-SCR activity over V2O5-WO3/CeO2-TiO2 catalyst.

    PubMed

    Cheng, Kai; Liu, Jian; Zhang, Tao; Li, Jianmei; Zhao, Zhen; Wei, Yuechang; Jiang, Guiyuan; Duan, Aijun

    2014-10-01

    CeO2-TiO2 composite supports with different Ce/Ti molar ratios were prepared by a homogeneous precipitation method, and V2O5-WO3/CeO2-TiO2 catalysts for the selective catalytic reduction (SCR) of NOx with NH3 were prepared by an incipient-wetness impregnation method. These catalysts were characterized by means of BET, XRD, UV-Vis, Raman and XPS techniques. The results showed that the catalytic activity of V2O5-WO3/TiO2 was greatly enhanced by Ce doping (molar ratio of Ce/Ti=1/10) in the TiO2 support. The catalysts that were predominantly anatase TiO2 showed better catalytic performance than the catalysts that were predominantly fluorite CeO2. The Ce additive could enhance the surface adsorbed oxygen and accelerate the SCR reaction. The effects of O2 concentration, ratio of NH3/NO, space velocity and SO2 on the catalytic activity were also investigated. The presence of oxygen played an important role in NO reduction. The optimal ratio of NH3/NO was 1/1 and the catalyst had good resistance to SO2 poisoning. PMID:25288555

  7. Atomic Layer Deposition of p-Type Epitaxial Thin Films of Undoped and N-Doped Anatase TiO2.

    PubMed

    Vasu, K; Sreedhara, M B; Ghatak, J; Rao, C N R

    2016-03-01

    Employing atomic layer deposition, we have grown p-type epitaxial undoped and N-doped anatase TiO2(001) thin films on c-axis Al2O3 substrate. From X-ray diffraction and transmission electron microscopy studies, crystallographic relationships between the film and the substrate are found to be (001)TiO2//(0001)Al2O3 and [1̅10]TiO2//[011̅0]Al2O3. N-doping in TiO2 thin films enhances the hole concentration and mobility. The optical band gap of anatase TiO2 (3.23 eV) decreases to 3.07 eV upon N-doping. The epitaxial films exhibit room-temperature ferromagnetism and photoresponse. A TiO2-based homojunction diode was fabricated with rectification from the p-n junction formed between N-doped p-TiO2 and n-TiO2. PMID:26963716

  8. Antimicrobial effects of TiO(2) and Ag(2)O nanoparticles against drug-resistant bacteria and leishmania parasites.

    PubMed

    Allahverdiyev, Adil M; Abamor, Emrah Sefik; Bagirova, Malahat; Rafailovich, Miriam

    2011-08-01

    Nanotechnology is the creation of functional materials, devices and systems at atomic and molecular scales (1-100 nm), where properties differ significantly from those at a larger scale. The use of nanotechnology and nanomaterials in medical research is growing rapidly. Recently, nanotechnologic developments in microbiology have gained importance in the field of chemotherapy. Bacterial strains that are resistant to current antibiotics have become serious public health problems that raise the need to develop new bactericidal materials. Metal oxide nanoparticles, especially TiO(2) and Ag(2)O nanoparticles, have demonstrated significant antibacterial activity. Therefore, it is thought that this property of metal oxide nanoparticles could effectively be used as a novel solution strategy. In this review, we focus on the unique properties of nanoparticles, their mechanism of action as antibacterial agents and recent studies in which the effects of visible and UV-light induced TiO(2) and Ag(2)O nanoparticles on drug-resistant bacteria have been documented. In addition, from to previous results of our studies, antileishmanial effects of metal oxide nanoparticles are also demonstrated, indicating that metal oxide nanoparticles can also be effective against eukaryotic infectious agents. Conversely, despite their significant potential in antimicrobial applications, the toxicity of metal oxide nanoparticles restricts their use in humans. However, recent studies infer that metal oxide nanoparticles have considerable potential to be the first-choice for antibacterial and antiparasitic applications in the future, provided that researchers can bring new ideas in order to cope with their main problem of toxicity. PMID:21861623

  9. In situ SERS monitoring of photocatalytic organic decomposition using recyclable TiO2-coated Ag nanowire arrays

    NASA Astrophysics Data System (ADS)

    Bao, Zhi Yong; Liu, Xin; Dai, Jiyan; Wu, Yucheng; Tsang, Yuen Hong; Lei, Dang Yuan

    2014-05-01

    Recently, semiconductor and noble metal complex nanomaterials have attracted ever-increasing attention because of the realization of multiple functionalities in a single entity. In this study, Ag-TiO2 core-shell nanocomposites were synthesized by hydrolysis of butyl titanate on the surface of Ag nanowires. Due to efficient electron transfer at the Ag-TiO2 interface, the as-prepared nanocomposites exhibit much higher photocatalytic activity than bare TiO2 films, as demonstrated by the enhanced photodegradation rate of R6G and methyl blue molecules. In the meanwhile, such nanocomposites serve as a high-sensitivity surface-enhanced Raman scattering (SERS) substrate for in situ monitoring of the photocatalytic decomposition reaction, and the substrate is recyclable due to its self-cleaning function. Full-wave numerical calculations reveal that the improved photocatalysis and SERS efficiencies are attributed to the largely enhanced electromagnetic near-field in the nanocomposites. Our results point out that bifunctional semiconductor-metal hybrids hold great promise for simultaneously detecting and decomposing organic pollutants in the environment.

  10. Catalyst performance and mechanism of catalytic combustion of dichloromethane (CH2Cl2) over Ce doped TiO2.

    PubMed

    Cao, Shuang; Wang, Haiqiang; Yu, Feixiang; Shi, Mengpa; Chen, Shuang; Weng, Xiaole; Liu, Yue; Wu, Zhongbiao

    2016-02-01

    TiO2 and Ce/TiO2 were synthesized and subsequently used for the catalytic combustion of DCM. TiO2 had abundant Lewis acid sites and was responsible for the adsorption and the rupture of C-Cl bonds. However, TiO2 tended to be inactivated because of chloride poisoning due to the adsorption and accumulation of Cl species over the surface. While, Ce/TiO2 obtained total oxidation of CH2Cl2 at 335°C and exhibited stable DCM removal activity on 100h long-time stability tests at 330°C without any catalyst deactivation. The doped cerium generated Ce(3+) chemical states and surface active oxygen, and therefore played important roles from two aspects as follows. First of all, the poisoning of Cl for Ce/TiO2 was inhibited to some extent by CeO2 due to the rapid removal of Cl on the surface of CeO2, which has been verified by NH3-IR characterization. In the other hand, CeO2 enhanced the further deep oxidation of C-H from byproducts and retained the certain oxidation of CO to CO2. Based on the DRIFT characterization and the catalysts activity tests, a two-step reaction pathway for the catalytic combustion of DCM on Ce/TiO2 catalyst was proposed. PMID:26550781

  11. Low temperature synthesis of iodine-doped TiO 2 nanocrystallites with enhanced visible-induced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ma, Yi; Fu, Ji-Wen; Tao, Xia; Li, Xin; Chen, Jian-Feng

    2011-03-01

    Iodine-doped TiO 2 nanocrystallites (denoted as I-TNCs) were prepared via a newly developed triblock copolymer-mediated sol-gel method at a temperature of 393 K. I-doping, crystallization and the formation of porous structure have been simultaneously achieved. The obtained particles were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-vis spectrophotometer. The results indicated that the as-prepared I-TNCs possessed a diameter of ca. 5 nm with anatase crystalline structure and a specific surface area of over 200 m 2 g -1. The presence of iodine expanded the photoresponse in visible light range, and led to enrich in surface hydroxyl group on the TiO 2 surface. Compared with the commercial photocatalyst P25, the I-TNCs significantly enhanced the photocatalytic efficiency in the degradation of rhodamine B and 2,4-dichlorophenol, and the I-TNCs with 2.5 mol% doping ratio exhibited the best photocatalytic activity.

  12. A First-Principle Study of Synergized O2 Activation and CO Oxidation by Ag Nanoparticles on TiO2(101) Support.

    PubMed

    Jia, Chuanyi; Zhang, Guozhen; Zhong, Wenhui; Jiang, Jun

    2016-04-27

    We performed density functional theory (DFT) calculations to investigate the synergized O2 activation and CO oxidation by Ag8 cluster on TiO2(101) support. The excellent catalytic activity of the interfacial Ag atoms in O2 dissociation is ascribed to the positive polarized charges, upshift of Ag d-band center, and assistance of surface Ti5c atoms. CO oxidation then takes place via a two-step mechanism coupled with O2 dissociation: (i) CO + O2 → CO2 + O and (ii) CO + O → CO2. The synergistic effect of CO and O2 activations reduces the oxidation energy barrier (Ea) of reaction (i), especially for the up-layered Ag atoms not in contact with support. It is found that the coadsorbed CO and O2 on the up-layered Ag atoms form a metal-stable four-center O-O-CO structure motif substantially promoting CO oxidation. On the oxygen defective Ag8/TiO2(101) surface, because of the decreased positive charges and the down-shift of d-band centers in Ag, the metal cluster exhibits low O2 adsorption and activation abilities. Although the dissociation of O2 is facilitated by the TiO2(101) defect sites, the dissociated O atoms would cover the defects so strongly that further CO oxidation would be prohibited unless much extra energy is introduced to recreate oxygen defects. PMID:27049335

  13. Agglomeration of Ag and TiO2 nanoparticles in surface and wastewater: Role of calcium ions and of organic carbon fractions.

    PubMed

    Topuz, Emel; Traber, Jacqueline; Sigg, Laura; Talinli, Ilhan

    2015-09-01

    This study aims to investigate factors leading to agglomeration of citrate coated silver (AgNP-Cit), polyvinylpyrrolidone coated AgNPPVP and titanium dioxide (TiO2) nanoparticles in surface waters and wastewater. ENPs (1 mg/L) were spiked to unfiltered, filtered, ultrafiltered (<10 kDa and <1 kDa) samples. Z-average particle sizes were measured after 1 h, 1 day and 1 week. AgNP-PVP was stable in all fractions of the samples and kept their original size around 60 nm over 1 week. Agglomeration of AgNP-Cit and TiO2 was positively correlated with Ca(2+) concentration, but dissolved organic carbon concentrations > 2 mg/L contributed to stabilizing these NP. Moreover, agglomeration of AgNP-Cit in the various organic matter fractions showed that high molecular weight organic compounds such as biopolymers provide stabilization in natural water. A generalized scheme for the agglomeration behavior of AgNP-Cit, AgNP-PVP and TiO2 in natural waters was proposed based on their relation with Ca(2+), Mg(2+) and DOC concentration. PMID:26057362

  14. Preparation of K-doped TiO2 nanostructures by wet corrosion and their sunlight-driven photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Shin, Eunhye; Jin, Saera; Kim, Jiyoon; Chang, Sung-Jin; Jun, Byung-Hyuk; Park, Kwang-Won; Hong, Jongin

    2016-08-01

    K-doped TiO2 nanowire networks were prepared by the corrosion reaction of Ti nanoparticles in an alkaline (potassium hydroxide: KOH) solution. The prepared nanostructures were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD) and photoluminescence (PL) spectra. Their sunlight-driven photocatalytic activity was also investigated with differently charged dye molecules, such as methylene blue, rhodamine B and methyl orange. The adsorption of the dye molecules on the photocatalyst surface would play a critical role in their selective photodegradation under sunlight illumination.

  15. Inkjet printable luminescent Eu3+-TiO2 doped in sol gel matrix for paper tagging.

    PubMed

    Attia, M S; Elsaadany, Soad A; Ahmed, Kawther A; El-Molla, Mohamed M; Abdel-Mottaleb, M S A

    2015-01-01

    Europium (III) with different concentrations (0.2, 0.4 and 0.8 %)-TiO(2) doped silica composite systems were sensitized by sol-gel method. Different spectroscopic and microscopic tools characterized the composites. The Europium ion incorporated into the liquid silica-titania solution acts as red light emission center in the luminescent materials. This luminescent nano composite pigment has great potential of application in preparing luminescent ink. Inkjet printer loaded with the prepared ink to show its potential usage as tagging material performed the printing test on a white paper. PMID:25591996

  16. Fabrication of Nb-Doped TiO2 Transparent Conducting Films by Postdeposition Annealing under Nitrogen Atmosphere

    NASA Astrophysics Data System (ADS)

    Okazaki, Sohei; Ohkubo, Junpei; Nakao, Shoichiro; Hirose, Yasushi; Hitosugi, Taro; Hasegawa, Tetsuya

    2012-11-01

    Here, we report that highly conductive polycrystalline anatase Nb-doped TiO2 (TNO) thin films can be prepared via crystallization of amorphous precursors under N2 atmosphere. An optimized TNO film on a glass substrate exhibited a low resistivity of 8.4 ×10-4 Ω cm and an absorbance of 6% at a wavelength of 460 nm. These transport and optical properties were comparable to those of TNO films fabricated by vacuum annealing. This demonstrates the potential of TNO as an electrode for GaN-based light-emitting diodes.

  17. Nanostructured Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel thin films for integrated optics

    NASA Astrophysics Data System (ADS)

    Predoana, Luminita; Preda, Silviu; Anastasescu, Mihai; Stoica, Mihai; Voicescu, Mariana; Munteanu, Cornel; Tomescu, Roxana; Cristea, Dana

    2015-08-01

    The nanostructured multilayer silica-titania or silica-titania-alumina films doped with Er3+ were prepared by sol-gel method. The sol-gel method is a flexible and convenient way to prepare oxide films on several types of substrates, and for this reason it was extensively investigated for optical waveguides fabrication. The selected molar composition was 90%SiO2-10%TiO2 or 85%SiO2-10%TiO2-5% Al2O3 and 0.5% Er2O3. The films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Spectroellipsometry (SE), as well as by Atomic Force Microscopy (AFM) and photoluminescence (PL). The films deposited on Si/SiO2 substrate by dip-coating or spin-coating, followed by annealing at 900 °C, presented homogenous and continuous surface and good adherence to the substrate. Differences were noticed in the structure and properties of the prepared films, depending on the composition and the number of deposited layers. Channel optical waveguides were obtained by patterning Er3+-doped SiO2-TiO2 and SiO2-TiO2-Al2O3 sol-gel layers deposited on oxidized silicon wafers.

  18. Facile synthesis of hierarchical Ag3PO4/TiO2 nanofiber heterostructures with highly enhanced visible light photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Xie, Jinlei; Yang, Yefeng; He, Haiping; Cheng, Ding; Mao, Minmin; Jiang, Qinxu; Song, Lixin; Xiong, Jie

    2015-11-01

    Heterostructured semiconductor nanostructures have provoked great interest in the areas of energy, environment and catalysis. Herein, we report a novel hierarchical Ag3PO4/TiO2 heterostructure consisting of nearly spherical Ag3PO4 particles firmly coupled on the surface of TiO2 nanofibers (NFs). The construction of Ag3PO4/TiO2 heterostructure with tailored morphologies, compositions and optical properties was simply achieved via a facile and green synthetic strategy involving the electrospinning and solution-based processes. Owing to the synergetic effects of the components, the resulting hybrid heterostructures exhibited much improved visible light photocatalytic performance, which could degrade the RhB dye completely in 7.5 min. In addition, the coupling of Ag3PO4 particles with UV-light-sensitive TiO2 NFs enabled full utilization of solar energy and less consumption of noble metals, significantly appealing for their practical use in new energy sources and environmental issues. The developed synthetic strategy was considered to be applicable for the rational design and construction of other heterostructured catalysts.

  19. A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO2/Ag-exchanged-zeolite-A nanocomposite

    NASA Astrophysics Data System (ADS)

    Nosrati, Rahimeh; Olad, Ali; Nofouzi, Katayoon

    2015-08-01

    The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO2/Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV-visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO2/Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO2/Ag-exchanged-zeolite-A nanocomposite additive with TiO2 to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination.

  20. Influence of the nanostructure of F-doped TiO2 films on osteoblast growth and function.

    PubMed

    Lozano, Daniel; Hernández-López, Juan M; Esbrit, Pedro; Arenas, Maria A; Gómez-Barrena, Enrique; de Damborenea, Juan; Esteban, Jaime; Pérez-Jorge, Concepción; Pérez-Tanoira, Ramón; Conde, Ana

    2015-06-01

    The aim of this study was to evaluate the proliferation and mineralization ability of mouse osteoblastic MC3T3-E1 cells on F-containing TiO2 films with different morphology and nanostructure that previously confirmed antibacterial properties. F-containing TiO2 films were fabricated by anodizing Ti-6Al-4V alloy ELI -grade 23. By using a mixture of H2SO4/HF acid at 20 V for 5 and 60 min, a TiO2 film grows with nanoporous (NP) and nanotubular (NT) features, characterized with a pore diameter of 20 and 100 nm, respectively. Fluoride-TiO2 barrier films (FBL) were produced in 1M NH4H2PO4/0.15M NH4F solution at constant voltage controlled at 20 V for 120 min. The amount of F incorporated in the nanostructured oxide films was 6 at % and of 4 at %, for the NP and NT, respectively, while for the FBL film was 12 at %. MC3T3-E1 cells exhibited different behavior when seeded and grown onto these surfaces. Thus, F-doped TiO2 films with NP structures increased proliferation as well as osteogenic gene expression and the mineralization capacity of these osteoblastic cells. These results confirm that anodizing process is suitable to fabricate multifunctional surfaces on Ti-6Al-4V alloy with improved not only antibacterial but also osteogenic properties useful for bone fixation of prosthetic devices PMID:25230841

  1. Improvement of sintering, nonlinear electrical, and dielectric properties of ZnO-based varistors doped with TiO2

    NASA Astrophysics Data System (ADS)

    Osama, A. Desouky; K, E. Rady

    2016-06-01

    The effects of TiO2 on sintering and nonlinear electrical properties of (98.5 ‑ x)ZnO–0.5MnO2–0.5Co,2O3‑0.5Bi2O3–xTiO2 (x = 0.3, 0.5, 0.7, 0.9 mol%) ceramic varistors prepared by the ceramic technique are investigated in this work. The optimum sintering temperature of the prepared samples is deduced by determining the firing shrinkage and water absorption percentages. The optimum sintering temperature is found to be 1200 °C, at which each of the samples shows a maximum firing shrinkage and minimum water absorption. Also minimum water absorption appears in a sample of x = 0.9 mol%. Higher sintering temperature and longer sintering time give rise to a reduction in bulk density due to the increased amount of porosity between the large grains of ZnO resulting from the rapid grain growth induced by the liquid phase sintering. The crystal size of ZnO decreases with increasing TiO2 doping. The addition of TiO2 improves the nonlinear coefficient and attains its maximum value at x = 0.7 mol% of TiO2, further addition negatively affects it. A decrease in capacitance consequently in the dielectric constant is recorded with increasing the frequency in a range of 30 kHz–200 kHz. The temperature and composition dependences of the dielectric constant and AC conductivity are also studied. The increase of temperature raises the dielectric constant because it increases ionic response to the field at any particular frequency.

  2. Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

    NASA Astrophysics Data System (ADS)

    Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

    2015-07-01

    Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet-visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films.

  3. Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

    PubMed Central

    Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

    2015-01-01

    Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet–visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films. PMID:26156001

  4. Efficient removal of herbicide 2,4-dichlorophenoxyacetic acid from water using Ag/reduced graphene oxide co-decorated TiO2 nanotube arrays.

    PubMed

    Tang, Yanhong; Luo, Shenglian; Teng, Yarong; Liu, Chengbin; Xu, Xiangli; Zhang, Xilin; Chen, Liang

    2012-11-30

    A new photocatalyst, Ag nanoparticles (NPs) and reduced graphene oxide (RGO) co-decorated TiO(2) nanotube arrays (NTs) (Ag/RGO-TiO(2) NTs), was designed and facilely produced by combining electrodeposition and photoreduction processes. The structures and properties of the photocatalysts were characterized. The ternary catalyst exhibited almost 100% photocatalytic removal efficiency of typical herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water under simulated solar light irradiation. The photodegradation rate toward 2,4-D over Ag/RGO-TiO(2) NTs is 11.3 times that over bare TiO(2) NTs. After 10 successive cycles with 1600 min of irradiation, Ag/RGO-TiO(2) NTs maintained as high 2,4-D removal efficiency as 97.3% with excellent stability and easy recovery, which justifies the photocatalytic system a promising application for herbicide removal from water. PMID:23062512

  5. Ag plasmonic nanostructures and a novel gel electrolyte in a high efficiency TiO2/CdS solar cell.

    PubMed

    Kumar, P Naresh; Deepa, Melepurath; Srivastava, Avanish Kumar

    2015-04-21

    A novel photoanode architecture with plasmonic silver (Ag) nanostructures embedded in titania (TiO2), which served as the wide band gap semiconducting support and CdS quantum dots (QDs), as light absorbers, is presented. Ag nanostructures were prepared by a polyol method and are comprised of clumps of nanorods, 15-35 nm wide, interspersed with globular nanoparticles and they were characterized by a face centered cubic lattice. Optimization of Ag nanostructures was achieved on the basis of a superior power conversion efficiency (PCE) obtained for the cell with a Ag/TiO2/CdS electrode encompassing a mixed morphology of Ag nano-rods and particles, relative to analogous cells with either Ag nanoparticles or Ag nanorods. Interfacial charge transfer kinetics was unraveled by fluorescence quenching and lifetime studies. Ag nanostructures improve the light harvesting ability of the TiO2/CdS photoanode via (a) plasmonic and scattering effects, which induce both near- and far-field enhancements which translate to higher photocurrent densities and (b) charging effects, whereby, photoexcited electron transfer from TiO2 to Ag is facilitated by Fermi level equilibration. Owing to the spectacular ability of Ag nanostructures to increase light absorption, a greatly increased PCE of 4.27% and a maximum external quantum efficiency of 55% (at 440 nm) was achieved for the cell based on Ag/TiO2/CdS, greater by 42 and 66%, respectively, compared to the TiO2/CdS based cell. In addition, the liquid S(2-) electrolyte was replaced by a S(2-) gel containing fumed silica, and the redox potential, conductivity and p-type conduction of the two were deduced to be comparable. Although the gel based cells showed diminished solar cell performances compared to their liquid counterparts, nonetheless, the Ag/TiO2/CdS electrode continued to outperform the TiO2/CdS electrode. Our studies demonstrate that Ag nanostructures effectively capture a significant chunk of the electromagnetic spectrum and aid QD

  6. Effects of acute systemic administration of TiO2, ZnO, SiO2, and Ag nanoparticles on hemodynamics, hemostasis and leukocyte recruitment.

    PubMed

    Haberl, Nadine; Hirn, Stephanie; Holzer, Martin; Zuchtriegel, Gabriele; Rehberg, Markus; Krombach, Fritz

    2015-01-01

    It has been suggested that engineered nanomaterials (ENM), once arrived in the circulation, may affect the cardiovascular system. The aim of this in vivo study was to screen major cardiovascular effects of acute systemic administration of a panel of five nanomaterials, TiO2 anatase (NM-101), TiO2 rutile (NM-104), ZnO (NM-110), SiO2 (NM-200) and Ag (NM-300). Mice were anesthetized and the ENM were injected at a dose of 1 mg/kg via a catheter placed in the left femoral artery. Hemodynamic parameters were determined by invasive measurement of blood pressure and non-invasive measurement of heart rate. Ten minutes after injection of the ENM, the formation of light/dye-induced thrombi was assessed in the cremasteric microcirculation by intravital microscopy. In addition, the numbers of rolling, firmly adherent and transmigrated leukocytes were recorded in postcapillary cremasteric venules over a time period of 120 min after injection of ENM by intravital microscopy. The systemic administration of a single dose of the ENM tested did not dramatically alter hemodynamic parameters or affect early steps of leukocyte recruitment. However, the presence of circulating TiO2 anatase, but not of TiO2 rutile, SiO2, ZnO or Ag nanoparticles, significantly accelerated thrombus formation in the murine microcirculation. Moreover, TiO2 anatase but not TiO2 rutile nanoparticles increased murine platelet aggregation in vitro. Taken together, only one of the five systemically administered ENM, TiO2 anatase, affected hemostasis, whereas none of the ENM tested in this screening study dramatically modulated hemodynamic parameters or early steps of leukocyte recruitment. PMID:25670207

  7. Photocatalytic removal of hazardous Ponceau S dye using Nano structured Ni-doped TiO2 thin film prepared by chemical method

    NASA Astrophysics Data System (ADS)

    Marathe, Sunil D.; Shrivastava, Vinod S.

    2015-02-01

    Many attempts have been made by researchers for the removal of various dyes using nano structured Ni-doped TiO2; however, removal of `hazardous Ponceau S dye' using nano structured Ni-doped TiO2 has been not studied yet. In the present work, environmental application of Nano structured Ni doped TiO2 has been studied. Nano structured Ni-doped TiO2 thin films were deposited by the chemical method on a glass substrate. The prepared thin film was characterized by XRD, SEM, and EDX. The crystal size calculated from XRD is about 26.2 nm. The SEM analysis reveals nano spherical morphology of average particle size about 92 nm. The optical analysis was carried by using UV-visible spectroscopy. The band gap estimated from absorbance spectra for thin film was around 3.5 eV, making suitable Ni-doped TiO2 for photocatalytic removal of hazardous Ponceau S dye. In photocatalytic application different parameters like dye concentration, contact time, pH, UV light and sunlight were optimized for the removal of Ponceau S dye, respectively. The change in chemical oxygen demand after photo catalytic treatment was also studied.

  8. Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application

    NASA Astrophysics Data System (ADS)

    Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

    2014-06-01

    A double-layered TiO2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm2), which is 105.7% higher than that of the CdS/TiO2 nanorod solar cell (0.53%).

  9. Sonophotocatalytic degradation of dye C.I. Acid Orange 7 by TiO2 and Ag nanoparticles immobilized on corona pretreated polypropylene non-woven fabric.

    PubMed

    Marković, Darka; Šaponjić, Zoran; Radoičić, Marija; Radetić, Tamara; Vodnik, Vesna; Potkonjak, Branislav; Radetić, Maja

    2015-05-01

    This study discusses the possibility of using corona pre-treated polypropylene (PP) non-woven fabric as a support for immobilization of colloidal TiO2 and Ag nanoparticles in order to remove dye C.I. Acid Orange 7 from aqueous solution. Dye removal efficiency by sonocatalysis, photocatalysis and sonophotocatalysis was evaluated on corona pre-treated fabric loaded with TiO2 nanoparticles, corona pre-treated fabric double loaded with TiO2 nanoparticles and corona pre-treated fabrics loaded with TiO2 nanoparticles before and after deposition of Ag nanoparticles. In addition, the stability of PP non-woven fabric during these processes was investigated. The substrates were characterized by SEM, EDX and AAS analyses. The change of the dye concentration was evaluated by UV-VIS spectrophotometry. Unlike sonocatalysis and photocatalysis, complete dye removal from both solution and non-woven fabric was obtained already after 240-270 min of sonophotocatalysis. Corona pre-treated PP non-woven fabric loaded with Ag nanoparticles prior to deposition of TiO2 nanoparticles provided excellent degradation efficiency and superior reusability. Sonophotocatalytic degradation of dye in the presence of all investigated samples was the most prominent in acidic conditions. Although this nanocomposite system ensured fast discoloration of dye solution, TOC values of water measured after sonophotocatalysis were not satisfactory because of PP degradation. Therefore, it is suggested to include TOC evaluation in each case study where different supports for TiO2 nanoparticles are used since these nanoparticles may guarantee the dye removal from solution but the stability of support could be problematic causing even more serious environmental impact. PMID:25487219

  10. Rapid flame synthesis of internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters for lithium ion storage

    NASA Astrophysics Data System (ADS)

    Li, Yunfeng; Hu, Yanjie; Shen, Jianhua; Jiang, Haibo; Min, Guoquan; Qiu, Shengjie; Song, Zhitang; Sun, Zhuo; Li, Chunzhong

    2015-11-01

    The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo6+ doping can improve the conductivity of electrode materials and facilitate rapid Li+ intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li+ ion storage ability as well as incorporates Mo6+. Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect of TiO2, Mo6+ and ultrafine MoO3 clusters. Moreover, the aerosol flame process with a unique temperature gradient opens a new strategy to design novel hybrid materials by the simultaneous doping and heteroassembly engineering for next-generation LIBs.The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo6+ doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo6+ doping can improve the conductivity of electrode materials and facilitate rapid Li+ intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li+ ion storage ability as well as incorporates Mo6+. Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect

  11. Synthesis rare earth doped TiO2 nanorods and their application in the photocatalytic degradation of lignin

    DOE PAGESBeta

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji Won; Gu, Baohua; Wang, Wei

    2015-01-01

    This research studied the degradation of macromolecular lignin in aqueous environments catalyzed by rare earth doped titania nonorods (RE-TiO2 NRs) under simulated sunlight irradiation. In this work, we developed a two-step process to synthesize the RE-TiO2 NRs. Protonated titanate nanotubes with layered structure and negative surface charges were first prepared by a hydrothermal approach, then rare earth metal ions were hemogeneously bound onto the titanate via electrostatic incorporation. The RE-TiO2 NRs with average diameter of ~10 nm were obtained through calcination treatment . Enhanced photocatalytic activities of the RE-TiO2 NRs were observed in comparison with undoped TiO2 NRs and commercialmore » TiO2 photocatalysts. Photooxidation of methyl orange, as probe reaction, was chosen to evaluate the efficiency of the photocatalysts, and Eu-TiO2 NRs showed the fastest apparent reaction rate constant, which was evaluated as 42*10-4 s-1 in this catalytic system. La3+, Sm3+, Eu3+ and Er3+ doped TiO2 NRs showed higher photocatalytic efficiency on the photo-oxidation of azo groups. We have demonstrated that natural macromolecule lignin could be photodegraded effectively and rapidly at room temperature under simulated sunlight irradiation with a light intensity of 36.8 0.2 mW cm-2. Catalyzed by RE-TiO2 NRs, the reaction mechanism of photocatalytic depolymerization of lignin was based on two reaction routes, which were revealed by spectroscopic analysis of intermediate products.« less

  12. Sol-gel synthesis, characterization and optical properties of mercury-doped TiO 2 thin films deposited on ITO glass substrates

    NASA Astrophysics Data System (ADS)

    Mechiakh, R.; Ben Sedrine, N.; Chtourou, R.

    2011-08-01

    The Hg-doped and undoped nano-crystalline TiO 2 films on ITO glass substrates surface and polycrystalline powders were prepared by sol-gel dip coating technique. The crystal structure and surface morphology of TiO 2 were characterized by means of X-ray diffractometer (XRD), atomic force microscope (AFM), spectrophotometer, Fourier-transform infrared (FTIR), and spectroscopic ellipsometry (SE). The results indicated that the powder of TiO 2, doped with 5% Hg in room temperature was only composed of the anatase phase whereas in the undoped powder exhibits an amorphous phase were present. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature 400 °C. The average crystallite size of the undoped TiO 2 films was about 8.17 nm and was increased with Hg-doping in the TiO 2 films. Moreover, the grains distributed more uniform and the surface roughness was greater in the Hg-doped TiO 2 films than in the undoped one. Refractive index and porosity were calculated from the measured transmittance spectrum. The values of the index of refraction are in the range (1.95-2.49) and the porosity is in the range (47-2.8). The coefficient of transmission varies from 60 to 90%. SE study was used to determine the annealing temperature effect on the optical properties in the wavelength range from 0.25 to 2 μm and the optical gap of the Hg-doped TiO 2 thin films.

  13. Synthesis and photocatalytic activity of co-doped mesoporous TiO 2 on Brij98/CTAB composite surfactant template

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaotong; Zhou, Guowei; Xu, Jing; Bai, Guangwei; Wang, Lei

    2010-06-01

    Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO 2 complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO 2 samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N 2 adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area ( SBET) of 279.0 m 2 g -1, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc r) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h.

  14. Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity.

    PubMed

    Zhou, Xiufeng; Lu, Juan; Jiang, Jingjing; Li, Xiaobin; Lu, Mengna; Yuan, Guotao; Wang, Zuoshan; Zheng, Min; Seo, Hyo Jin

    2014-01-01

    N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol-gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. PMID:24428848

  15. Nb doped TiO2 as a Cathode Catalyst Support Material for Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    O'Toole, Alexander W.

    In order to reduce the emissions of greenhouse gases and reduce dependence on the use of fossil fuels, it is necessary to pursue alternative sources of energy. Transportation is a major contributor to the emission of greenhouse gases due to the use of fossil fuels in the internal combustion engine. To reduce emission of these pollutants into the atmosphere, research is needed to produce alternative solutions for vehicle transportation. Low temperature polymer electrolyte membrane fuel cells are energy conversion devices that provide an alternative to the internal combustion engine, however, they still have obstacles to overcome to achieve large scale implementation. T he following work presents original research with regards to the development of Nb doped TiO2 as a cathode catalyst support material for low temperature polymer electrolyte membrane fuel cells. The development of a new process to synthesize nanoparticles of Nb doped TiO2 with controlled compositions is presented as well as methods to scale up the process and optimize the synthesis for the aforementioned application. In addition to this, comparison of both electrochemical activity and durability with current state of the art Pt on high surface area carbon black (Vulcan XC-72) is investigated. Effects of the strong metal-support interaction on the electrochemical behavior of these materials is also observed and discussed.

  16. Synthesis, characterization and binding interactions of amino acids coupled perylene diimides with colloidal doped and undoped TiO2

    NASA Astrophysics Data System (ADS)

    Kavery, E.; Nagarajan, N.; Paramaguru, G.; Renganathan, R.

    2015-07-01

    Two sensitizers based on amino acids coupled with perylene moiety having absorption in the visible region have been designed and their interaction with doped and undoped TiO2 for the application of dye sensitized solar cells (DSSCs) has been studied. The synthesized compounds PDI-PA and PDI-AA were characterized using 1H and 13C NMR, Mass and FT-IR spectroscopic techniques. The optical properties and lifetime measurements of the sensitizers were analyzed using various solvents with different polarity. The solvatochromism effect was studied using Lippert-Mataga plot. The electrochemical studies of both dyes were investigated in DMF with various scan rate ranging from 200 to 1000 mV s-1. Colloidal doped and undoped TiO2 was prepared and characterized by using absorption measurements. Binding ability of the sensitizers with the nanoparticles was studied through absorption, fluorescence quenching, cyclic voltammetry and FT-IR measurements. Results obtained from all the above analysis suggest the mode of quenching may be static. The binding constant values were calculated using Kamat-Fox equation indicates the binding behavior of the sensitizers with the nanoparticles. The fluorescence quenching was mainly attributed to electron transfer from the excited state of PDI's to the conduction band of colloidal semiconductors. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram.

  17. Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity

    PubMed Central

    2014-01-01

    N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. PMID:24428848

  18. Hydrogen Annealing Induced the Enhancement of Ferromagnetism in Cr-Doped TiO2 Anatase Films

    NASA Astrophysics Data System (ADS)

    Liu, Lifeng; Kang, Jinfeng; Wang, Yi; Zhang, Xing; Han, Ruqi

    2008-12-01

    Polycrystalline Cr-doped TiO2 (Cr0.05Ti0.95O2) anatase films have been prepared on Si(001) substrates by sol-gel method. The Cr0.05Ti0.95O2 anatase film annealed in air ambient shows weak ferromagnetism with a magnetic moment of 0.026 µB/Cr in a field of 3000 Oe at room temperature. After further annealed in a hydrogen atmosphere, the ferromagnetic response in the Cr0.05Ti0.95O2 anatase film is significantly enhanced, reaching a magnetic moment of 0.234 µB/Cr. X-ray diffraction (XRD) fails to detect the existence of second phases such as Cr or CrO2 in Cr0.05Ti0.95O2 films. X-ray photoelectron spectroscopy (XPS) study shows that Ti is in +4 valence state and Cr in +3 valence state. Oxygen vacancies are created in the Cr0.05Ti0.95O2 film after hydrogenation, suggested by the XPS measurement. These results suggest that oxygen vacancies created by hydrogen annealing play a role on ferromagnetism in the Cr-doped TiO2 anatase films.

  19. A novel ethanol gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures.

    PubMed

    Wang, Yuan; Liu, Lixin; Meng, Chuanmin; Zhou, Yun; Gao, Zhao; Li, Xuhai; Cao, Xiuxia; Xu, Liang; Zhu, Wenjun

    2016-01-01

    Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance. PMID:27615429

  20. Comparing Cr, and N only doping with (Cr,N)-codoping for enhancing visible light reactivity of TiO2

    SciTech Connect

    Li, Yuan; Wang, Wei; Qiu, Xiaofeng; Meyer III, Harry M; Paranthaman, Mariappan Parans; Eres, Gyula; Zhang, Zhenyu; Gu, Baohua

    2011-01-01

    The photoreactivity of titania (TiO2) nanoclusters with varying levels of N or Cr-doping, or (Cr,N)-codoping, was systematically investigated using photodegradation of methyl orange in aqueous suspensions. The shifting of the TiO2 absorption edge into the visible spectral region that is primarily attributable to band gap narrowing was found to be a reliable metric for estimating the photoreactivity of the doped nanoclusters. Compared to the weak response with undoped and N-doped TiO2, Cr-doping and (Cr, N)-codoping were found to significantly enhance photodegradation of methyl orange under visible light. The initial reaction rates increase from about 0 to above 1.6 10-2 min-1 when the doping concentration of Cr in TiO2 increases from 0 to 5%. In stark contrast, under UV irradiation, doping is not only ineffective but detrimental to the photoreactivity, and all doping including N or Cr only and (Cr, N)-codoping were found to reduce photoreactivity.

  1. N incorporation and electronic structure in N-doped TiO2(110) rutile

    SciTech Connect

    Cheung, Sau H.; Nachimuthu, Ponnusamy; Joly, Alan G.; Engelhard, Mark H.; Bowman, Michael K.; Chambers, Scott A.

    2007-02-08

    Epitaxial TiO2-xNx film growth under anion-rich conditions is characterized by nearly balanced incorporation rates for substitutional N (NO) and interstitial Ti (Tii). Tii donors fully compensate and stabilize N3-, but preclude the formation of p-type material. Hybridization occurs between Tii(IV) and NO3-, but the value of x is limited to ~0.02 under these conditions. Tii(IV)-NO3- states occur above the valence band maximum of pure TiO2, riving rise to enhanced optical absorption in the visible up to ~2.5 eV. Much higher NO and Tii concentrations result from using cation-rich conditions.

  2. Anodic fabrication and bioactivity of Nb-doped TiO2 nanotubes.

    PubMed

    Ding, Dongyan; Ning, Congqin; Huang, Lin; Jin, Fangchun; Hao, Yongqiang; Bai, Shuo; Li, Yan; Li, Ming; Mao, Dali

    2009-07-29

    We report anodic formation of Ti-Nb-O nanotubes on top of a Ti35Nb alloy, and in vitro bioactivity and stem cell response of the anodic nanotubes. It was found that the amorphous Ti-Nb-O nanotubes presented a significantly enhanced in vitro bioactivity (in simulated body fluids) compared to those of undoped TiO2 nanotubes and porous Ti-Nb-O without nanotubular structure. Similar to undoped TiO2 nanotubes, the Ti-Nb-O nanotubes also promote mesenchymal stem cell adhesion and fast formation of extracellular matrix (ECM) materials. The above findings make it possible to further explore the biological properties, such as cell proliferation and drug delivery, of a variety of Ti-alloy-based oxide nanotubes. PMID:19581696

  3. Photocatalytic enhancement of TiO2 by B and Zr co-doping and modulation of microstructure

    NASA Astrophysics Data System (ADS)

    Fu, Chengxin; Gong, Yinyan; Wu, Yitao; Liu, Jiaqi; Zhang, Zhen; Li, Can; Niu, Lengyuan

    2016-08-01

    Visible-light photodegradation test revealed that B and Zr co-doping can raise the photocatalytic ability of the undoped TiO2 by a fold. XRD crystallography and Raman phonon spectroscopy measurements suggest that the Zr4+ ions replace the Ti4+ ions while the B3+ ions occupy the interstitial sites, expanding the unit-cell volume and reducing crystallite size. The incorporation of interstitial boron dopants creates oxygen vacancies (Ovrad rad) and reduce Ti4+ to Ti3+ to form [Ovrad rad -Ti3+]+, which traps the carriers and prolongs carrier lifetime. Moreover, Zr4+ ions replace Ti4+ ions and form impurity levels, which could improve visible light response. The co-doped samples are benefited from both B interstitials and Zr substitutes.

  4. Electrode effects in dielectric spectroscopy measurements on (Nb+In) co-doped TiO2

    NASA Astrophysics Data System (ADS)

    Crandles, D. A.; Yee, S. M. M.; Savinov, M.; Nuzhnyy, D.; Petzelt, J.; Kamba, S.; Prokeš, J.

    2016-04-01

    Recently, several papers reported the discovery of giant permittivity and low dielectric loss in (Nb+In) co-doped TiO2. A series of tests was performed which included the measurement of the frequency dependence of the dielectric permittivity and alternating current (ac) conductivity of co-doped (Nb+In)TiO2 as a function of electrode type, sample thickness, and temperature. The data suggest that the measurements are strongly affected by the electrodes. The consistency between four-contact van der Pauw direct current conductivity measurements and bulk conductivity values extracted from two-contact ac conductivity measurements suggest that the values of colossal permittivity are, at least in part, a result of Schottky barrier depletion widths that depend on electrode type and temperature.

  5. Promotional effect of Si-doped V2O5/TiO2 for selective catalytic reduction of NOx by NH3.

    PubMed

    Pan, Yanxiao; Zhao, Wei; Zhong, Qin; Cai, Wei; Li, Hongyu

    2013-08-01

    TiO2 supports doped with different amounts of Si were prepared by a sol-gel method, and 1 wt% vanadia (V2O5) loaded on Si-doped TiO2 was obtained by an impregnation method. The mole ratio of Si/Ti was 0.2, NOx conversion exceeds 94% at 300 degrees C and GHSV of 41,324 hr(-1), which is about 20% higher than pure V2O5/TiO2. The catalysts were characterized by XRD, BET, TEM, FT-IR, NH3-TPD, XPS, H2-TPR, Raman and in situ DRIFTS. The results of FT-IR and XPS indicated that Si was doped into the TiO2 lattice successfully and a solid solution was obtained. V2O5 active component could be dispersed well on the support with the increasing of surface area of the catalyst, which was confirmed by Raman and XRD results. Above all, the numbers of acid sites (especially the Brønsted-acid) and oxidation properties were enhanced for Si-doped V2O5/TiO2 catalysts, which improved the deNOx catalytic activity. PMID:24520711

  6. Ultrasonic-assisted sol-gel synthesis of samarium, cerium co-doped TiO2 nanoparticles with enhanced sonocatalytic efficiency.

    PubMed

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi

    2015-09-01

    In this work, pure TiO2 and samarium, cerium mono-doped and co-doped TiO2 catalysts were synthesized by an ultrasonic-assisted sol-gel method and their sonocatalytic efficiency studied toward removal of Methyl Orange as a model organic pollutant from the textile industry. The relationship of structure and sonocatalytic performance of catalysts was established by using various techniques, such as XRD, TEM, SEM, EDX, DRS, and PL. A comparison on the removal efficiency of sonolysis alone and sonocatalytic processes was performed. The results showed that the samarium, cerium co-doped TiO2 catalyst with narrower band gap energy and smaller particle size leads to a rapid removal of pollutant. It was believed that Sm(3+) and Ce(4+) ions can serve as superficial trapping for electrons at conduction band of TiO2 and prolonged the lifetime of electron-hole pairs. Finally, the effect of synthesis and operational variables on the sonocatalytic activity of co-doped TiO2 catalyst was studied and optimized using response surface methodology as a statistical technique. The results showed that the maximum removal efficiency (96.33%) was achieved at the optimum conditions: samarium content of 0.6 wt%, cerium content of 0.82 wt%, initial pollutant concentration of 4.31 mg L(-1), catalyst dosage of 0.84 mg L(-1), ultrasonic irradiation power of 700 W, and irradiation time of 50 min. PMID:25682738

  7. Role of Ag2S coupling on enhancing the visible-light-induced catalytic property of TiO2 nanorod arrays

    PubMed Central

    Li, Zhengcao; Xiong, Shan; Wang, Guojing; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    In order to obtain a better photocatalytic performance under visible light, Ag2S-coupled TiO2 nanorod arrays (NRAs) were prepared through the electron beam deposition with glancing angle deposition (GLAD) technique, annealing in air, followed by the successive ionic layer absorption and reaction (SILAR) method. The properties of the photoelectrochemical and photocatalytic degradation of methyl orange (MO) were thus conducted. The presence of Ag2S on TiO2 NRAs was observed to have a significant improvement on the response to visible light. It’s resulted from that Ag2S coupling can improve the short circuit photocurrent density and enhance the photocatalytic activity remarkably. PMID:26790759

  8. Enhanced Photocatalytic Activity for H2 Evolution under Irradiation of UV–Vis Light by Au-Modified Nitrogen-Doped TiO2

    PubMed Central

    Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

    2014-01-01

    Background Purpose Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Methods Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV–vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. Results DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV–vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Conclusion Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and

  9. Bamboo leaf-assisted formation of carbon/nitrogen co-doped anatase TiO2 modified with silver and graphitic carbon nitride: novel and green synthesis and cooperative photocatalytic activity.

    PubMed

    Jiang, Zhifeng; Liu, Dong; Jiang, Deli; Wei, Wei; Qian, Kun; Chen, Min; Xie, Jimin

    2014-09-28

    We report a novel synthesis approach employing bamboo leaves as sources of both the C/N dopant and reductant to the formation of C/N co-doped TiO2 modified with Ag and g-C3N4 (Ag/CN-TiO2@g-C3N4). In this case, the ternary composite has a hierarchical structure and a large surface area, which increases the contact area of reactants. Degradation of rhodamine B (RhB) and hydrogen generation were carried out to evaluate the photocatalytic activity of as-prepared samples under visible light irradiation. It is found that with respect to single and binary catalysts, the Ag/CN-TiO2@g-C3N4 ternary composite shows the highest photocatalytic activity (degradation of RhB, H2 evolution from water splitting) as a result of the fast generation, separation and transportation of the photogenerated carriers, which was evidenced by photoluminescence measurements and free radical/hole scavenging experiments. At last, a possible photocatalytic mechanism under visible light irradiation was proposed. The novel and green synergistic approach presented here could provide a facile yet effective method for designing other visible light active non-metal co-doped TiO2 based photocatalysts with enhanced activity and high chemical stability. PMID:25102976

  10. Synthesis and spectroscopic characterization of nanoparticles of TiO2 doped with Pt produced via the self-combustion route

    NASA Astrophysics Data System (ADS)

    Lopera, A. A.; Chavarriaga, E. A.; Estupiñan, H. A.; Valencia, I. C.; Paucar, C.; Garcia, C. P.

    2016-05-01

    Titanium oxide (TiO2) is the most important semiconductor used in photocatalysis. For that reason, most recent scientific studies have focused on improving the absorbance of this material in the visible region. In this paper, we report on the production of nanopowders of TiO2 doped with platinum via the solution combustion synthesis method, using glycine as a fuel at concentrations of 0.3, 0.6, 0.9, and 1.2% w/w of Pt with respect to TiO2 (Pt / TiO2), in order to study the influence of the dopant content on the absorbance spectrum in the visible region. The structure of the samples was characterized using x-ray diffraction and Raman spectroscopy, which confirmed the production of a pure anatase phase. VIS diffuse reflectance spectroscopy confirmed that in the visible region the samples doped with Pt absorb within the range of 400 nm to 800 nm. Field emission scanning electron microscopy and transmission electron microscopy showed the formation of TiO2 nanoparticles with an average size of 13 nm and with spherical morphology. Colorimetry (Commission Internationale de l’Eclairage L *, a *, b *) confirmed photocatalytic activity for the degradation of rhodamine B using visible light. It was concluded that the route of synthesis and the Pt content play important roles in the absorbance spectrum and the activation energy of TiO2.

  11. Photoelectrochemical characteristics of TiO2 nanorod arrays grown on fluorine doped tin oxide substrates by the facile seeding layer assisted hydrothermal method

    NASA Astrophysics Data System (ADS)

    Sui, Mei-rong; Han, Cui-ping; Gu, Xiu-quan; Wang, Yong; Tang, Lu; Tang, Hui

    2016-05-01

    TiO2 nanorod arrays (NRAs) were prepared on fluorine doped tin oxide (FTO) substrates by a facile two-step hydrothermal method. The nanorods were selectively grown on the FTO regions which were covered with TiO2 seeding layer. It took 5 h to obtain the compact arrays with the nanorod length of ~2 μm and diameter of ~50 nm. The photoelectrochemical (PEC) properties of TiO2 NRAs are also investigated. It is demonstrated that the TiO2 NRAs indicate the good photoelectric conversion ability with an efficiency of 0.22% at a full-wavelength irradiation. A photocurrent density of 0.21 mA/cm2 is observed at 0.7 V versus the saturated calomel electrode (SCE). More evidences suggest that the charge transferring resistance is lowered at an irradiation, while the flat-band potential ( V fb) is shifted towards the positive side.

  12. High visible light photocatalytic property of Co2+-doped TiO2 nanoparticles with mixed phases

    NASA Astrophysics Data System (ADS)

    Zhao, Cong; Shu, Xin; Zhu, Da-chuan; Wei, Shang-hai; Wang, Yu-xin; Tu, Ming-jing; Gao, Wei

    2015-12-01

    Mixed phases Co2+-doped TiO2 nanoparticles have been prepared by a novel method combined with sol-gel and hydrothermal methods. The section of sol-gel method, sol, provides an unstable colloidal reaction system for the next reaction process. The hydrothermal method is to treat the above reaction system to prepare undoped and doped samples. The as-prepared samples have been characterized by XRD, SEM, TEM, HRTEM and UV-vis spectroscopy. The results show that the as-prepared samples contain three titania polymorphs: brookite, rutile and anatase phases. These titania polymorphs probably form polymorph-junctions that can extend the lifetime of photogenerated electron-hole pairs. The photocatalytic activity has been evaluated by the photocatalytic degradation of Rhodamine B in air under visible-light irradiation. The degradation results indicate that the photocatalytic activity of as-prepared samples is higher than that of Degussa P25, especially the doped sample. This is ascribed to the fact that the phases with smaller band gap can enhance visible-light photocatalytic activity, the polymorph-junctions effectively extend the photoelectron lifetime and the nano size effect and Co-doping induce the shift of the absorption edge into the visible-light region. Furthermore, the XRD, SEM, and TEM data indicate that Co2+-doping results in the decrease of particle size.

  13. Multiscale anode materials in lithium ion batteries by combining micro- with nanoparticles: design of mesoporous TiO2 microfibers@nitrogen doped carbon composites

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Rechberger, Felix; Primc, Darinka; Niederberger, Markus

    2015-08-01

    TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability.TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After

  14. Dual-Wavelength Irradiation and Dox Delivery for -Cancer Cell Ablation with Photocatalytic Pr Doped TiO2 /NGO -Hybrid Nanocomposite.

    PubMed

    Jang, Hongje; Choi, Myung-Ho; Yim, Yeajee; Kim, Young-Kwan; Min, Dal-Hee

    2015-08-26

    Herein, hybrid nanocomposite of praseodymium doped TiO2 nanocrystals and graphene oxide nanosheets are prepared by facile hydrothermal treatment. As-synthesized Pr-TiO2 /NGO hybrid nanocomposite exhibits enhanced photocatalytic activity under visible light irradiation by the intact graphene oxide and doped lanthanide mediated band gap narrowing compared to TiO2 . Moreover, high payload and controlled release of doxorubicin by charge reversal of hybrid nanocomposite at endosomal pH and near-infrared irradiation mediated efficient photothermal conversion provide highly favorable features in therapeutic applications. Through the combination of these three distinctive therapeutic modalities, highly efficient trimodal cancer cell ablation is demonstrated. PMID:26085286

  15. A direct synthesis of B-doped TiO2 and its photocatalytic performance on degradation of RhB

    NASA Astrophysics Data System (ADS)

    Li, Liang; Yang, Yulin; Liu, Xinrong; Fan, Ruiqing; Shi, Yan; Li, Shuo; Zhang, Lingyun; Fan, Xiao; Tang, Pengxiao; Xu, Rui; Zhang, Wenzhi; Wang, Yazhen; Ma, Liqun

    2013-01-01

    B-doped TiO2 was synthesized by a direct hydrolyzation of n-tetrabutyl titanate in a solution of boric acid, and was treated by hydro-thermal synthesis. The powder was characterized by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM), surface photoviolet spectra, UV-visible absorption spectra and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) degradation was used as a probe reaction to evaluate the photocatalytic activity of B-doped TiO2 under simulate sunlight, and excellent photocatalytic performance was achieved.

  16. In vitro degradation, cytocompatibility and hemolysis tests of CaF2 doped TiO2-SiO2 composite coating on AZ31 alloy

    NASA Astrophysics Data System (ADS)

    Li, Bing; Chen, Yun; Huang, Wei; Yang, Wenzhong; Yin, Xiaoshuang; Liu, Ying

    2016-09-01

    In this study, a CaF2 doped TiO2-SiO2 composite coating was successfully coated onto AZ31 alloy by sol-gel method. Electrochemical tests, in vitro degradation, direct cellular experiment and hemolysis tests were conducted and the results showed that the CaF2 doped TiO2-SiO2 composite coating can not only improve the corrosion resistance, but also enhance the biocompatibility of AZ31 alloy. XRD, SEM and EDX were also performed to characterize the crystalline structures, morphologies and chemical compositions of the coatings.

  17. Correlations of Optical Absorption, Charge Trapping, and Surface Roughness of TiO2 Photoanode Layer Loaded with Neat Ag-NPs for Efficient Perovskite Solar Cells.

    PubMed

    Yang, Dongwook; Jang, Jae Gyu; Lim, Joohyun; Lee, Jin-Kyu; Kim, Sung Hyun; Hong, Jong-In

    2016-08-24

    We systematically investigated the effect of silver nanoparticles (Ag-NPs) on the power conversion efficiency (PCE) of perovskite solar cells (PSCs). Neat, spherical Ag-NPs at loading levels of 0.0, 0.5, 1.0, and 2.0 wt % were embedded into the titanium dioxide (TiO2) photoanode layer. The plasmonic effect of the Ag-NPs strongly enhanced the incident light absorption over a wide range of the visible wavelength region in addition to the inherent absorbance of the perovskite sensitizer. The low conduction energy level of the Ag-NPs compared to that of TiO2 provides trap sites for free charge carriers. Thus, the correlation between the enhancement of the optical absorption and the number of charge traps provided by the Ag-NPs is critical to determine the device performance, especially current density (Jsc) and PCE. This is confirmed by the quantitative comparison of the incident light absorption and the time-resolved photoluminescence decay according to the loading levels of the Ag-NPs in the TiO2 layer. The absorption enhancement from 380 to 750 nm in the UV-visible spectrum is proportional to the increase in the loading levels of the Ag-NPs. However, the Jsc increases with the device with 0.5 wt % Ag-NPs and gradually decreases with increases in the loading level above 0.5 wt % because of the different contributions to the absorbance and the charge trapping by different Ag-NP loading levels. In addition, the suppression of the surface roughness with dense packing by the Ag-NPs helps to improve the Jsc and the following PCE. Consequently, the PCE of the PSC with 0.5 wt % Ag-NPs is increased to 11.96%. These results are attributed to the balance between increased absorbance by the localized surface plasmon resonance and the decreased charge trapping as well as the decreased surface roughness of the TiO2 layer with the Ag-NPs. PMID:27471777

  18. TiO(2) doping by hydroxyurea at the nucleation stage: towards a new photocatalyst in the visible spectral range.

    PubMed

    Azouani, R; Tieng, S; Chhor, K; Bocquet, J-F; Eloy, P; Gaigneaux, E M; Klementiev, K; Kanaev, A V

    2010-10-01

    We report an original method of preparation of OCN-doped TiO(2) for photocatalysis in the visible spectral range. The preparation is achieved by a sol-gel route using titanium tetraisopropoxide precursor. Special attention was paid to fluid micromixing, which enables homogeneous reaction conditions in the reactor bulk and monodispersity of the produced clusters/nanoparticles. The dopant hydroxyurea (HyU, CH(4)N(2)O(2)) is injected into the reactive fluid at the nucleation stage, which lasts tens of milliseconds. The doping results in a strong yellow coloration of the nanocolloids due to the absorption band in the spectral range 380-550 nm and accelerates the aggregation kinetics of both nuclei at the induction stage and sub-nuclei units (clusters) at the nucleation stage. FTIR, Raman and UV-visible absorption analyses show the formation of a stable HyU-TiO(2) complex. EXAFS spectra indicate no appreciable changes of the first-shell Ti atom environment. The doping agent takes available surface sites of TiO(2) clusters/nanoparticles attaining ∼10% molar loading. The reaction kinetics then accelerates due to a longer collisional lifetime between nanoparticles induced by the formation of a weak [double bond, length as m-dash]OTi bond. The OCN-group bonding to titanium atoms produces a weakening of the C[double bond, length as m-dash]O double bond and a strengthening of the C-N and N-O bonds. PMID:20714464

  19. A robust super-paramagnetic TiO2:Fe3O4:Ag nanocomposite with enhanced photo and bio activities on polyester fabric via one step sonosynthesis.

    PubMed

    Harifi, Tina; Montazer, Majid

    2015-11-01

    High intensity ultrasound was used for the synthesis and simultaneous deposition of TiO2:Fe3O4:Ag nanocomposites on polyester surface providing a feasible route for imparting magnetic and enhanced antibacterial and self-cleaning activities with controllable hydrophilicity/hydrophobicity at low temperature. Synergistic impact of sonochemistry and physical effects of ultrasound originating from implosive collapse of bubbles were responsible for the formation and adsorption of nanomaterials on the fabric surface during ultrasound irradiation. The increase in photocatalytic activity of TiO2 was obtained attributing to the co-operation of iron oxide and silver nanoparticles nucleated on TiO2 surface boosting the electron-hole pair separation and prolonging their recombination rate. The process was further optimized in terms of reagents concentrations including Fe(2+)/TiO2 and Ag/TiO2 molar ratios using central composite design in order to achieve the best self-cleaning property of the treated fabric. The magnetic measurements indicated the super-paramagnetic behavior of the treated fabric with saturation magnetization of 4.5 (emu/g). Findings suggest the potential of the proposed facial method in producing an intelligent fabric with durable multi-functional activities that can be suitable for various applications including medical, military, bio-separation, bio-sensors, magneto graphic printing, magnetic screens and magnetic filters. PMID:25899439

  20. Multiscale anode materials in lithium ion batteries by combining micro- with nanoparticles: design of mesoporous TiO2 microfibers@nitrogen doped carbon composites.

    PubMed

    Cheng, Wei; Rechberger, Felix; Primc, Darinka; Niederberger, Markus

    2015-09-01

    TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability. PMID:26220269

  1. Ab initio studies of Nb-N-S tri-doped TiO2 with enhanced visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ren, Dahua; Cheng, Junxia; Cheng, Xinlu

    2016-06-01

    The electronic and optical properties of Nb-N-S tri-doped anatase TiO2 were investigated within the frame of the density functional theory (DFT) plus U method. Results show that a significant red-shift effect and improvement of visible-light absorption for Nb-N-S tri-doped TiO2 are observed with respect to pure TiO2 and S-N codoped TiO2. At the same time, the enhanced visible-light photocatalytic activity of tri-doped TiO2 is derived from the narrowing band gap, the appearance of Nb 4d state at the bottom of conduction band and the mixture of N 2p, S 3p states forming new defect levels at the top of valance band, which is excellently consistent with the previous experiment. Moreover, S ion leads to the lattice distortion and promotes the visible-light photocatalytic activity. Furthermore, the absorbance of 1.39NbNS-TiO2 accords well with the experimental result in the visible region. It is also found that the 2.78NbNS-TiO2 can be easily grown under O-rich condition and have the strongest absorbance from 2.0 to 4.2 eV among four models.

  2. Joint Effects of Photoactive TiO2 and Fluoride-Doping on SnO2 Inverse Opal Nanoarchitecture for Solar Water Splitting.

    PubMed

    Gun, Yun; Song, Gwang Yeom; Quy, Vu Hong Vinh; Heo, Jaeyeong; Lee, Hyunjung; Ahn, Kwang-Soon; Kang, Soon Hyung

    2015-09-16

    Inverse opal (IO) films of tin dioxide (SnO2) were fabricated on polystyrene (PS) beads (diameter=350 nm (±20 nm) with a spin coating method. To compensate for the large band gap (Eg=3.8 eV), a thin TiO2 shell was deposited on the SnO2-IO films with atomic layer deposition (ALD), which produced shells with thicknesses of 10-40 nm. The morphological changes and crystalline properties of the SnO2 and TiO2-coated SnO2 (herein after referred to as TiO2/SnO2) IO films were investigated with field-emission scanning electron microscopy and X-ray diffraction, respectively. The photoelectrochemical (PEC) behavior of the samples was tested in a 0.1 M KOH solution under 1 sun illumination (100 mW/cm2 with an AM 1.5 filter). The highest PEC performance was obtained with the TiO2(10 nm)/SnO2 IO films, which produced a photocurrent density (Jsc) of 4.67 mA/cm2 at 0.5 V (vs NHE) and was sequentially followed by the TiO2(20 nm)/SnO2-IO, TiO2(30 nm)/SnO2-IO, TiO2 (40 nm)/SnO2-IO and SnO2 IO films. Overall, the thin TiO2 shell covered on the SnO2-IO core enhanced Jsc by 3 orders of magnitude, which in turn the PEC activity. This is mainly ascribed to the extremely low charge-transfer resistance (Rct) in the photoelectrode/electrolyte and at the TiO2/SnO2 interface, as well as the contribution of the photoactive TiO2 layer, which has an Eg of 3.2 eV. Moreover, to improve the electrical conductivity of the core SnO2 IO film, the films were doped with 10 mol % of F. The F- doped films were labeled as the FTO IO film. The Rct of the FTO-IO films decreased because of the improved electronic conductivity, enhancing the PEC performance of the TiO2(10 nm)/FTO-IO films by approximately 20%. The core-shell nanowire mesh nanoarchitecture is therefore suggested to provide an insight for designing the peculiar structure based on the material's properties and the engineering of their band gap energy for highly efficient PEC performance. PMID:26322646

  3. [Study on preparation of lanthanum-doped TiO2 nanometer thin film materials and its photocatalytic activity].

    PubMed

    Zheng, Huai-li; Tang, Ming-fang; Gong, Ying-kun; Deng, Xiao-jun; Wu, Bang-hua

    2003-04-01

    In this paper, lanthanum-doped TiO2 nanometer film materials coated on glass were prepared in Ti(OBu)4 precursor solutions by sol-gel processing. Transmittance and photocatalytic activity were respectively investigated and tested for these nanometer thin films prepared with different amount of lanthanum (La), different amount of polyethylene glycol (PEG), and different coating layer times. Some reactive mechanisms were also discussed. For one layer La-addition had little effect on the film transmissivity; but the photocatalytic activity was significantly improved due to La-addition. With increasing PEG, the transmittance of the film decreased for one layer film; but its photocatalytic activity did not rise. Increasing layer number did not affect the transmissivity of multilayer film. After coating two times, increasing layer number did not significantly improve the photocatalytic activity. The highest photocatalytic activity and best transmissivity were obtained for two layer TiO2 film when the dosage of lanthanum was 0.5 g and the dosage of polyethylene was 0.2 g in the precursor solutions. These materials will probably be used in the protection of environment, waste water treatment, and air purification. PMID:12961861

  4. N-derived signals in the x-ray photoelectron spectra of N-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Yu, Y. P.; Xing, X. J.; Xu, L. M.; Wu, S. X.; Li, S. W.

    2009-06-01

    The plasma-assisted molecular beam epitaxial anatase TiO2-xNx (x <0.3) films were chosen to investigate the N-derived variation in the x-ray photoelectron spectroscopy (XPS). With increasing nitrogen concentration, the small chemical shift and the shoulder of the main peak emerge in the N 1s, O 1s, or Ti 2p3/2 core level spectra. In combination with the experimental results obtained from x-ray diffraction and atomic force microscopy, the variations in the spectra could be ascribed to the microstructural distortion. This distortion, induced by the N3- substitution for lattice O2-, could slightly decrease the average ionicity of the Ti-O (or N) bonds. In addition, the other N 1s features (at 399.8 and 401.8 eV) and the oxygen vacancy are also discussed. For the N-doped TiO2, this work introduces a correlation between the microstructural properties and the XPS signals.

  5. Bonding and Anti-bonding Modes of Plasmon Coupling Effects in TiO2-Ag Core-shell Dimers

    NASA Astrophysics Data System (ADS)

    Li, Quanshui; Zhang, Zhili

    2016-01-01

    Bonding and anti-bonding modes of plasmon coupling effects are numerically investigated in TiO2-Ag core-shell nano dimers. First, splitting phenomena of the coupled anti-bonding modes are observed under the longitudinal polarization when the distance between the monomers decreases to a certain level. Second, one of the split resonance modes is identified to be formed by the dipole anti-bonding mode of the monomers from charge density distribution patterns. Those split modes have similar redshift behaviors as the coupled dipole bonding modes in the same situations. Furthermore, the intensities of those anti-bonding modes weaken with decreasing distance between the monomers, because of the interaction of the induced dipole moment in the monomers and the charge distribution variation on the facing surfaces of the gap by the coulomb attraction. Other split bands are the higher-order mode (octupole-like or triakontadipole-like), which do not have obvious peak-shift behavior, and the intensities have very little attenuation with decreasing distance. Finally, the coupling of the bonding and anti-bonding modes under the longitudinal polarization is symmetric (bonding).

  6. Bonding and Anti-bonding Modes of Plasmon Coupling Effects in TiO2-Ag Core-shell Dimers

    PubMed Central

    Li, Quanshui; Zhang, Zhili

    2016-01-01

    Bonding and anti-bonding modes of plasmon coupling effects are numerically investigated in TiO2-Ag core-shell nano dimers. First, splitting phenomena of the coupled anti-bonding modes are observed under the longitudinal polarization when the distance between the monomers decreases to a certain level. Second, one of the split resonance modes is identified to be formed by the dipole anti-bonding mode of the monomers from charge density distribution patterns. Those split modes have similar redshift behaviors as the coupled dipole bonding modes in the same situations. Furthermore, the intensities of those anti-bonding modes weaken with decreasing distance between the monomers, because of the interaction of the induced dipole moment in the monomers and the charge distribution variation on the facing surfaces of the gap by the coulomb attraction. Other split bands are the higher-order mode (octupole-like or triakontadipole-like), which do not have obvious peak-shift behavior, and the intensities have very little attenuation with decreasing distance. Finally, the coupling of the bonding and anti-bonding modes under the longitudinal polarization is symmetric (bonding). PMID:26763719

  7. Effect of low Fe3+ doping on characteristics, sonocatalytic activity and reusability of TiO2 nanotubes catalysts for removal of Rhodamine B from water.

    PubMed

    Pang, Yean Ling; Abdullah, Ahmad Zuhairi

    2012-10-15

    Fe-doped titanium dioxide (TiO(2)) nanotubes were prepared using sol-gel followed by hydrothermal methods and characterized using various methods. The sonocatalytic activity was evaluated based on oxidation of Rhodamine B under ultrasonic irradiation. Iron ions (Fe(3+)) might incorporate into the lattice and intercalated in the interlayer spaces of TiO(2) nanotubes. The catalysts showed narrower band gap energies, higher specific surface areas, more active surface oxygen vacancies and significantly improved sonocatalytic activity. The optimum Fe doping at Fe:Ti=0.005 showed the highest sonocatalytic activity and exceeded that of un-doped TiO(2) nanotubes by a factor of 2.3 times. It was believed that Fe(3+) doping induced the formation of new states close to the valence band and conduction bands and accelerated the separation of charge carriers. Leached Fe(3+) could catalyze Fenton-like reaction and led to an increase in the hydroxyl radical (OH) generation. Fe-doped TiO(2) nanotubes could retain high degradation efficiency even after being reused for 4 cycles with minimal loss of Fe from the surface of the catalyst. PMID:22939090

  8. Enhanced photovoltaic performance of a quantum dot-sensitized solar cell using a Nb-doped TiO2 electrode

    NASA Astrophysics Data System (ADS)

    Jiang, Lei; You, Ting; Deng, Wei-Qiao

    2013-10-01

    In this work Nb-doped anatase TiO2 nanocrystals are used as the photoanode of quantum-dot-sensitized solar cells. A solar cell with CdS/CdSe quantum dots co-sensitized 2.5 mol% Nb-doped anatase TiO2 nanocrystals can achieve a photovoltaic conversion efficiency of 3.3%, which is almost twice as high as the 1.7% obtained by a cell based on undoped TiO2 nanocrystals. The incident photon-to-current conversion efficiency can reach as high as 91%, which is a record for all quantum-dot-sensitized solar cells. Detailed analysis shows that such an enhancement is due to improved lifetime and diffusion length of electrons in the solar cell.

  9. Enhanced photovoltaic performance of a quantum dot-sensitized solar cell using a Nb-doped TiO2 electrode.

    PubMed

    Jiang, Lei; You, Ting; Deng, Wei-Qiao

    2013-10-18

    In this work Nb-doped anatase TiO2 nanocrystals are used as the photoanode of quantum-dot-sensitized solar cells. A solar cell with CdS/CdSe quantum dots co-sensitized 2.5 mol% Nb-doped anatase TiO2 nanocrystals can achieve a photovoltaic conversion efficiency of 3.3%, which is almost twice as high as the 1.7% obtained by a cell based on undoped TiO2 nanocrystals. The incident photon-to-current conversion efficiency can reach as high as 91%, which is a record for all quantum-dot-sensitized solar cells. Detailed analysis shows that such an enhancement is due to improved lifetime and diffusion length of electrons in the solar cell. PMID:24045808

  10. Photodegradation of ibuprofen by TiO2 co-doping with urea and functionalized CNT irradiated with visible light - Effect of doping content and pH.

    PubMed

    Yuan, Ching; Hung, Chung-Hsuang; Li, Huei-Wen; Chang, Wei-Hsian

    2016-07-01

    Ibuprofen (IBP) is one kind of non-steroidal anti-inflammatory drugs (NSAIDs), which are classified as Pharmaceuticals and Personal Care Products (PPCPs). IBP possesses bioactive property and the substantial use of IBP results in a harmful impact on bioreceptors even in small concentrations. Accordingly, the treatment of these wastewaters is important before discharging them into the ecosystem. The photodegradation of IBP with TiO2 co-doped with functionalized CNTs (CNT-COOH and CNT-COCl) and urea, named as N-doping CNT/TiO2, irradiated with visible light of 410 nm was investigated in this study. The titanium tetrachloride was used as the precursor of Ti. The N-doping CNT-COCl/TiO2 photocatalysts exhibited a better crystalline structure and smaller crystal size than the N-doping CNT-COOH/TiO2 photocatalyst. It might largely ascribe to strong binding between acyl chloride functional group and TiO2. About 85.0%-86.0% of IBP was degraded with N-doping CNT/TiO2 within 120 min at natural condition, which obeyed the pseudo first order reaction and the rate constant was 4.45 × 10(-3)-1.22 × 10(-2) min(-1) and 5.03 × 10(-3)-1.47 × 10(-2) min(-1) for N-doping CNT-COOH/TiO2 and N-doping CNT-COCl/TiO2, respectively. The best IBP degradation of 87.9%-89.0% was found at pH 5, which indicated superoxide radicals (O2(-)) played a key role. The optimal pH was majorly dominated by the nature of IBP and N-doping CNT/TiO2. A successful synergy effect of TiO2 and dopants was exhibited and this mainly attributed to the strong binding strength by functional group of acyl chloride (COCl) and carboxylic acid (COOH). In summary, IBP could be effectively photodegraded by the fabricated N-doping CNT/TiO2 photocatalysts. PMID:27145421

  11. Plasmon enhanced photoelectrochemical sensing of mercury (II) ions in human serum based on Au@Ag nanorods modified TiO2 nanosheets film.

    PubMed

    Zhang, Yong; Shoaib, Anwer; Li, Jiaojiao; Ji, Muwei; Liu, Jiajia; Xu, Meng; Tong, Bin; Zhang, Jiatao; Wei, Qin

    2016-05-15

    Taking advantages of the monodisperse TiO2 nanosheets (NSs) with high active crystal face exposure and the tunable localized surface plasmon resonance (LSPR) properties of Au@Ag nanorods (NRs), this study demonstrated that TiO2 NSs film with trace amount of Au@Ag NRs modification possess a strong enhancement of photocurrent response, which was remarkably inhibited with the addition of mercury (II) ions (Hg(2+)). Based on the selective decrease of photocurrent with the addition of Hg(2+), a simple photoelectrochemical (PEC) sensor has been assembled. The PEC sensor exhibits wide linear range (0.01-10nM), low detection limit (2.5pM), satisfying selectivity, reproducibility and acceptable stability for Hg(2+) detection. The feasibility of this method for practical application in human serum has been evaluated and the result was satisfactory. This PEC sensing method would provide a potential application for Hg(2+) detection in clinical diagnosis. PMID:26785311

  12. Treatment of olive mill wastewater by photooxidation with ZrO2-doped TiO2 nanocomposite and its reuse capability.

    PubMed

    Sponza, Delia Teresa; Oztekin, Rukiye

    2016-04-01

    Zirconium dioxide (zirconia, ZrO2)-doped TiO2 (TiO2/ZrO2) nanocomposite was used for the photocatalytic oxidation of pollutant parameters [COD components (CODtotal, CODdissolved and CODinert)], polyphenols (catechol, 3-hydroxybenzoic acid, tyrosol and 4-hydroxybenzoic acid) and total polyaromatic amines [aniline, 4-nitroaniline, o-toluidine and o-anisidine] from the olive mill effluent wastewaters at different operational conditions such as at different mass ratios of ZrO2 (50, 25, 14, 10 and 5 wt%) in the TiO2/ZrO2 nanocomposite, at different TiO2/ZrO2 photocatalyst concentrations (1, 4, 15 and 50 mg/L) and pH values (4.0-7.0-10.0) under 300 W UV irradiations, respectively. Under the optimized conditions (pH = 4.6, 15 mg/L ZrO2/TiO2 nanocomposite with a ZrO2 mass ratio of 14 wt%, 300 W UV light, after 60 min photooxidation time, at 21°C), the maximum CODdissolved, total phenol and total aromatic amines photooxidation yields were 99%, 89% and 95%, respectively. High pollutant removal (89%) yields after sequential five times utilization of ZrO2/TiO2 nanocomposite show that this catalyst can be effectively used commercially in the treatment of olive mill effluent. PMID:26560364

  13. Half-metallic behaviour in doped TiO2 (rutile) with double impurities: ab initio calculation

    NASA Astrophysics Data System (ADS)

    Fakhim Lamrani, A.; Belaiche, M.; Benyoussef, A.; El Kenz, A.

    2013-12-01

    Dilute magnetic oxides are without doubt among the most interesting classes of magnetic materials. However, the nature of their electronic structure and magnetic exchange is far from understood. Here, we apply the ab initio augmented spherical wave (ASW) method, with corrected generalised gradient approximation to study the electronic structure and magnetic properties of doped TiO2 rutile with double impurities. The study reveals a half-metallic ferromagnetic behaviour for Ti1-2x Cr x Mo x O2, and the local magnetic moments of the impurities and their oxidation states agree with the charge transfer between Cr and Mo, which would lead to the ferromagnetic state through the double-exchange mechanism in transition metal oxides.

  14. Preparation and photoelectric properties of Fe-doped mesoporous TiO2 thick films used in DSSC

    NASA Astrophysics Data System (ADS)

    Xie, Yian; Shen, Yue; Gu, Feng; Lu, Huina; Wu, Mingming; Wang, Linjun

    2009-08-01

    Fe-doped mesoporous TiO2 (M-TiO2-Fe) thick films were prepared by sol-gel and screen printing process. Raman characteristics results show that the M-TiO2-Fe thick film possesses a certain degree of the anatase phase, which may have advantages on photocatalysis and photovoltaic ability. Derived from small angel X-Ray diffraction (SAXRD), the films exhibit mesoporous structure with pore size around 7-8 nm. Eg of the films was obviously narrowed from 3.4 eV to 3.0 eV, which allows the thick films using more light to initiate photovoltaic process. Dye-sensitized solar cell (DSSC) based on M-TiO2-Fe was structured and chlorophyl was used as sensitizers. The solar cells have an open circuit voltage above 260mV.

  15. Solution-Processed Polyfluorene:Naphthalenediimide-N-Doped TiO2 Hybrids for Ultraviolet Photodetector Applications

    NASA Astrophysics Data System (ADS)

    Memisoglu, Gorkem; Varlikli, Canan; Diker, Halide

    2013-12-01

    In this study, highly efficient ultraviolet (UV) photodetectors based on a solution-processed system are introduced. Nitrogen-doped TiO2 nanoparticles are embedded in poly(9,9-dioctylfluorenyl-2,7-yleneethynylene) (PFE): N, N'-bis- n-butyl-1,4,5,8-naphthalenediimide (BNDI) (3:1 wt.%) blends. An UV- active layer of [(PFE:BNDI)(3:1):ammonium hydroxide-TiO2] [9:1 wt.%] gave a photoresponsivity value of 545 ± 6.92 mA/W at -4 V under 1 mW/cm2 UV light at 365 nm, and this value was increased to 597 ± 9.22 mA/W on annealing the active layer at 60°C. The efficiencies obtained are strongly dependent on the nitrogen source nature, their donor-acceptor relationship, and the morphological interaction with the PFE:BNDI blend.

  16. Sonocatalytic degradation of azo fuchsine in the presence of the Co-doped and Cr-doped mixed crystal TiO2 powders and comparison of their sonocatalytic activities.

    PubMed

    Wang, Jun; Lv, Yanhui; Zhang, Zhaohong; Deng, Yingqiao; Zhang, Liquan; Liu, Bin; Xu, Rui; Zhang, Xiangdong

    2009-10-15

    In order to degrade some pollutants effectively under ultrasonic irradiation, the Co-doped and Cr-doped mixed crystal TiO(2) powders, with high sonocatalytic activity, were prepared as sonocatalyst. The Co-doped and Cr-doped mixed crystal TiO(2) powders as sonocatalyst were prepared through sol-gel and heat-treated methods from tetrabutylorthotitanate, and then were characterized by XRD and TG-DTA technologies. In order to compare and evaluate the sonocatalytic activity of the Co-doped and Cr-doped mixed crystal TiO(2) powders, the low power ultrasound was as an irradiation source and the azo fuchsine was chosen as a model compound to be degraded. The degradation process was investigated by UV-vis, TOC, ion chromatogram and HPLC techniques. The results indicated that the sonocatalytic activity of Cr-doped mixed crystal TiO(2) powder was higher than that of Co-doped and undoped mixed crystal TiO(2) powder during the sonocatalytic degradation of the azo fuchsine in aqueous solution. These results may be of great significance for driving sonocatalytic method to treat non- or low-transparent industrial wastewaters. PMID:19467773

  17. Effect of N-doping on the photocatalytic activity of sol-gel TiO2.

    PubMed

    Nolan, Nicholas T; Synnott, Damian W; Seery, Michael K; Hinder, Steven J; Van Wassenhoven, Axel; Pillai, Suresh C

    2012-04-15

    In order to study the visible light photocatalytic activity of nitrogen doped titanium dioxide, the interaction between nitrogen dopant sources and titania precursors during sol-gel synthesis is investigated. N-TiO(2) was synthesised using the sol-gel method using 1,3-diaminopropane as a nitrogen source. Samples were annealed several temperatures and the percentage of rutile present determined by X-ray diffraction to be 0% (500°C), 46% (600°C), and 94% (700°C). The reducing amounts of anatase at higher temperatures are studied using FTIR, which suggests the absence of any polymeric chains formed by the chelating agents, which would normally extend anatase-to-rutile transformation temperatures. Differential scanning calorimetry shows that crystalliation occurs before 500°C, providing the crystalline form determined by XRD at 500°C. Increased temperature also resulted in diminished visible light absorption capability, with only the 500°C sample showing significant absorption in the visible region. XPS studies revealed that nitrogen remained within the TiO(2) lattice at higher temperatures. Consequent with the reduced visible light absorption capacity, photocatalytic activity also reduced with increased annealing temperature. Degradation kinetics of methylene blue, irradiated with a 60 W house-bulb, resulted in first order degradation rates constants of 0.40 × 10(-2), 0.19 × 10(-2), and 0.22 × 10(-2)min(-1) for 500, 600, and 700°C respectively. Degradation of Degussa P25 was minimal under the same conditions, and that of undoped TiO(2) was 0.02 × 10(-2)min(-1). Similarly, using 4-chlorophenol under solar irradiation conditions, the N-doped sample at 500°C substantially out-performed the undoped sample. These results are discussed in the context of the effect of increasing temperature on the nature of the band gap. PMID:21963170

  18. 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

  19. Photoelectrochemical aptasensor for the sensitive and selective detection of kanamycin based on Au nanoparticle functionalized self-doped TiO2 nanotube arrays.

    PubMed

    Xin, Yanmei; Li, Zhenzhen; Zhang, Zhonghai

    2015-11-01

    In this communication, a new photoelectrochemical aptasensor with Au nanoparticle functionalized self-doped TiO2 nanotube arrays (Au/SD-TiO2 NTs) as the core sensing unit and aptamers as the recognition unit was set up to accomplish the sensitive and selective detection of kanamycin with the lowest detection limit of 0.1 nM. PMID:26382019

  20. Preparation of N doped TiO2 via microwave-assisted method and its photocatalytic activity for degradation of Malathion.

    PubMed

    Kadam, A N; Dhabbe, R S; Kokate, M R; Gaikwad, Y B; Garadkar, K M

    2014-12-10

    We report herein, nitrogen doped TiO2 nanostructure synthesized by simple microwave assisted method, where ammonia was used as hydrolyzing agent. The synthesized nanomaterials were characterized by means of X-ray diffraction (XRD) which demonstrated that N-doped TiO2 is in anatase phase with average crystallite size of 10nm. Doping of N into the lattice of TiO2 was supported by X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), CHNS analysis, energy dispersive spectroscopy (EDS). The diffuse reflectance spectroscopy (DRS) showed shifting of absorption edge toward the visible region. Thermogravimetric-differential thermal analysis (TGA-DTA) points out N-doped TiO2 nanoparticles are thermally stable. In order to achieve maximum degradation efficiency, the effect of catalyst loading, pH and light sources (UV and sunlight) were studied. A maximum 97% degradation efficiency was achieved under optimized conditions. A 80% reduction in the chemical oxygen demand (COD) was observed after 150min that indicated mineralization of Malathion. The cytotoxicological studies indicate that photocatalytically degraded products were less toxic as compared to Malathion. PMID:24996208

  1. Low-temperature hydrothermal synthesis of N-doped TiO2 from small-molecule amine systems and their photocatalytic activity.

    PubMed

    Bao, Nan; Niu, Jun-Jian; Li, Yuan; Wu, Guo-Lin; Yu, Xiao-Hong

    2013-01-01

    Nitrogen-doped TiO2 nanopowders have been successfully synthesized by a one-step hydrothennal route under soft-chemistry conditions (150 degrees, 8 h) without high-temperature calcination using seven different types of nitrogen dopants: methylamine, ethylamine, diethylamine, ethylenediamine, triethylamine, triethanolamine and ammonia. X-ray diffraction, transmission electron microscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption isothenns and Fourier transform infrared spectroscopy were used to analyse the as-synthesized TiO2 powders. The results indicated that nitrogen was doped effectively and the structure and morphology of the titania samples were strongly influenced by the nitrogen sources. Among the investigated nitrogen sources, the diethylamine system was clearly superior to the other small-molecule amine or ammonia systems due to the broad-spectrum response (between 400 and 700 nm) of the interstitial nitrogen-doped TiO2 nanopowders. The diethylamine N-doped TiO2 had the largest pore volume (0.39 ml x g(-1)) and showed a well-aligned anatase phase. The visible-light photocatalytic degradation of liquid X-3B used as a probe reaction demonstrated that the removal rate over the diethylamine material reached 99.7% in 90 min. PMID:24617053

  2. Preparation and characterization of TiO2 and Si-doped octacalcium phosphate composite coatings on zirconia ceramics (Y-TZP) for dental implant applications

    NASA Astrophysics Data System (ADS)

    Bao, Lei; Liu, Jingxiao; Shi, Fei; Jiang, Yanyan; Liu, Guishan

    2014-01-01

    In order to prevent the low temperature degradation and improve the bioactivity of zirconia ceramic implants, TiO2 and Si-doped octacalcium phosphate composite coating was prepared on zirconia substrate. The preventive effect on low temperature degradation and surface morphology of the TiO2 layer were studied. Meanwhile, the structure and property changes of the bioactive coating after doping Si were discussed. The results indicate that the dense TiO2 layer, in spite of some microcracks, inhibited the direct contact of the water vapor with the sample's surface and thus prevented the low temperature degradation of zirconia substrates. The acceleration aging test shows that the ratio of the monoclinic phase transition decreased from 10% for the original zirconia substrate to 4% for the TiO2-coated substrate. As to the Si-doped octacalcium phosphate coating prepared by biomimetic method, the main phase composition of the coating was octacalcium phosphate. The morphology of the coating was lamellar-like, and the surface was uniform and continuous with no cracks being observed. It is suggested that Si was added into the coating both through substituting for PO43- and doping as NaSiO3.

  3. Significant enhancement in the photocatalytic activity of N, W co-doped TiO2 nanomaterials for promising environmental applications.

    PubMed

    Thind, Sapanbir S; Wu, Guosheng; Tian, Min; Chen, Aicheng

    2012-11-30

    In this work, a mesoporous N, W co-doped TiO(2) photocatalyst was synthesized via a one-step solution combustion method, which utilized urea as the nitrogen source and sodium tungstate as the tungsten source. The photocatalytic activity of the N, W co-doped TiO(2) photocatalyst was significantly enhanced by a facile UV pretreatment approach and was evaluated by measuring the rate of photodegradation of Rhodamine B under both UV and visible (λ > 420) light. Following the UV pretreatment, the UV photocatalytic activity of the N, W co-doped TiO(2) was doubled. In terms of visible light activity, the UV pretreatment resulted in an extraordinary >12 fold improvement. In order to gain insight into this substantial enhancement, the N, W co-doped TiO(2) photocatalysts were studied using x-ray diffraction, transmission electron microscopy, N(2) physisorption, UV-vis absorbance spectroscopy and x-ray photoelectron spectroscopy prior to and following the UV pretreatment. Our experimental results have revealed that this significant augmentation of photocatalytic activity may be attributed to several synergetic factors, including increase of the specific surface area, reduction of the band gap energy and the removal of carbon impurities. PMID:23110785

  4. Preparation of N doped TiO2 via microwave-assisted method and its photocatalytic activity for degradation of Malathion

    NASA Astrophysics Data System (ADS)

    Kadam, A. N.; Dhabbe, R. S.; Kokate, M. R.; Gaikwad, Y. B.; Garadkar, K. M.

    2014-12-01

    We report herein, nitrogen doped TiO2 nanostructure synthesized by simple microwave assisted method, where ammonia was used as hydrolyzing agent. The synthesized nanomaterials were characterized by means of X-ray diffraction (XRD) which demonstrated that N-doped TiO2 is in anatase phase with average crystallite size of 10 nm. Doping of N into the lattice of TiO2 was supported by X-ray photoelectron spectroscopy (XPS), Fourier transform-infrared spectroscopy (FT-IR), CHNS analysis, energy dispersive spectroscopy (EDS). The diffuse reflectance spectroscopy (DRS) showed shifting of absorption edge toward the visible region. Thermogravimetric-differential thermal analysis (TGA-DTA) points out N-doped TiO2 nanoparticles are thermally stable. In order to achieve maximum degradation efficiency, the effect of catalyst loading, pH and light sources (UV and sunlight) were studied. A maximum 97% degradation efficiency was achieved under optimized conditions. A 80% reduction in the chemical oxygen demand (COD) was observed after 150 min that indicated mineralization of Malathion. The cytotoxicological studies indicate that photocatalytically degraded products were less toxic as compared to Malathion.

  5. Fabrication of Fe-doped TiO2 nanoparticles and investigation of photocatalytic decolorization of reactive red 198 under visible light irradiation.

    PubMed

    Moradi, Halimeh; Eshaghi, Akbar; Hosseini, Seyed Rahman; Ghani, Kamal

    2016-09-01

    In this research, Fe-doped TiO2 nanoparticles with various Fe concentrations (0. 0.1, 1, 5 and 10wt%) were prepared by a sol-gel method. Then, nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), BET surface area, photoluminescence (PL) spectroscopy and UV-vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of the nano-particles was evaluated through degradation of reactive red 198 (RR 198) under UV and visible light irradiations. XRD results revealed that all samples contained only anatase phase. DRS showed that the Fe doping in the titania induced a significant red shift of the absorption edge and then the band gap energy decreased from 3 to 2.1eV. Photocatalytic results indicated that TiO2 had a highest photocatalytic decolorization of the RR 198 under UV irradiation whereas photocatalytic decolorization of the RR 198 under visible irradiation increased in the presence of Fe-doped TiO2 nanoparticles. Among the samples, Fe-1wt% doped TiO2 nanoparticles showed the highest photocatalytic decolorization of RR198 under visible light irradiation. PMID:27150776

  6. Gasochromic switching of Ta and Pd-doped nanocrystalline TiO2 thin films.

    PubMed

    Domaradzki, J; Wojcieszak, D; Prociow, E; Kaczmarek, D; Winiarski, A; Szade, J

    2011-10-01

    In this work TiO2:(Ta, Pd) thin films with gasochromic properties have been described. Thin films were prepared by reactive magnetron sputtering process using mosaic Ti-Ta-Pd target. The amounts of dopants were 2.54 at.% and 12.36 at.% of Ta and Pd, respectively. The results of optical measurements performed at presence of ethanol and additional heating of the sample up to 350 degrees C have shown an abrupt change of transmission level from 80% down to 10% in VIS and in IR range. The gasochromic change was very fast. Moreover, rapid cooling (down to room temperature) in an air ambient results in stable thin film coloration. The reverse effect (bleaching) was obtained after annealing at 500 degrees C in an ambient air. PMID:22400253

  7. Sm3+ doped TiO2 as optical oxygen sensor material

    NASA Astrophysics Data System (ADS)

    Eltermann, Marko; Utt, Kathriin; Lange, Sven; Jaaniso, Raivo

    2016-01-01

    The luminescence properties of Sm3+ in sol-gel-made nanostructural TiO2 were shown to depend on surrounding gas environment. Both the intensity and lifetime of the luminescence increased with increasing oxygen content varied between 0% and 100% in the O2/N2 mixture at normal pressure. The luminescence decay kinetics after pulsed excitation at 355 nm followed the stretched exponential function with the value of stretching exponent equal to 0.4-0.5. The mechanism of oxygen sensitivity was interpreted as resonant excitation energy transfer from Sm3+ to the acceptor defects, the latter being switched on and off the resonance by electron exchange with surface-adsorbed oxygen. Oxygen vacancy related defects were proposed as most likely candidates of energy acceptors. The studied material can be used for luminescence lifetime based oxygen sensing.

  8. Thin layer of ordered boron-doped TiO2 nanotubes fabricated in a novel type of electrolyte and characterized by remarkably improved photoactivity

    NASA Astrophysics Data System (ADS)

    Siuzdak, Katarzyna; Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Karczewski, Jakub; Ryl, Jacek

    2015-12-01

    This paper reports a novel method of boron doped titania nanotube arrays preparation by electrochemical anodization in electrolyte containing boron precursor - boron trifluoride diethyl etherate (BF3 C4H10O), simultaneously acting as an anodizing agent. A pure, ordered TiO2 nanotubes array, as a reference sample, was also prepared in solution containing a standard etching compound: ammonium fluoride. The doped and pure titania were characterized by scanning electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and by means of electrochemical methods. The B-doping decidedly shifts the absorption edge of TiO2 nanotubes towards the visible light region and significantly inhibits the radiative recombination processes. Despite the fact that the doped sample is characterized by 4.6 lower real surface area when compared to pure titania, it leads to the decomposition of methylene blue in 93%, that is over 2.3 times higher than the degradation efficiency exhibited by the undoped material. The formation rate of hydroxyl radicals (rad OH) upon illumination significantly favours boron doped titania as a photocatalytic material. Moreover, the simple doping of TiO2 nanotubes array results in the enhancement of generated photocurrent from 120 μA/cm2 to 350 μA/cm2 registered for undoped and doped electrode, respectively.

  9. The effect of F --doping and temperature on the structural and textural evolution of mesoporous TiO 2 powders

    NASA Astrophysics Data System (ADS)

    Yu, Jia-Guo; Yu, Jimmy C.; Cheng, Bei; Hark, S. K.; Iu, Kwansai

    2003-09-01

    Mesoporous F --doped TiO 2 powders were prepared by hydrolysis of titanium tetraisopropoxide (TTIP) in a mixed NH 4F-H 2O solution. Effects of F - ion content and calcination temperatures on the phase composition and porosity of mesoporous titania were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and BET surface areas. The results showed the BET surface area ( SBET) of the pure and doped powders dried at 100°C ranged from 260 to 310 m 2/g as determined by nitrogen adsorption. With increasing calcination temperatures, the SBET values of the calcined titania powders decreased due to the increase in crystalline size. The pore size distribution was bimodal with fine intra-particle pore and larger inter-particle pore as determined by nitrogen adsorption isotherms. The peak pore diameter of intra-particle pore increases with increasing F - ion content. At 700°C, all the titania powders exhibit monomodal pore size distributions due to the complete collapse of the intra-particle pores. The crystallization of anatase was obviously enhanced due to F --doping at 400°C and 500°C. Moreover, with increasing F - ion concent, F - ions not only suppressed the formation of brookite phase at low temperature, but also prevented phase transition of anatase to rutile at high temperature.

  10. Structural, optical, and ferromagnetic properties of Co-doped TiO2 films annealed in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Jianping; Shi, Shaobo; Li, Lan; Zhang, Xiaosong; Wang, Yaxin; Chen, Ximing; Wang, Jianfeng; Lv, Liya; Zhang, Fengming; Zhong, Wei

    2010-03-01

    Polycrystalline anatase Ti1-xCoxO2 (x =0-0.06) films have been fabricated by sol-gel spin coating. The effects of Co doping on the structural, optical, and magnetic properties are investigated. It is shown that oxygen vacancies and/or defects in the films are generated during thermal treatment in vacuum. Co doping reduces crystal quality and inhibits crystalline grain growth. Due to the introduction of Co, photoluminescence (PL) spectra become weak and the band gap emission has a blueshift. PL spectra reveal that the solubility of Co is lower than 0.02. At 300 K, the saturated magnetization is around 1.8 μB/Co, which is independent of the concentration of Co. This value is approximately equivalent to the average magnetic moment of bulk metallic cobalt (1.75 μB/Co). Zero-field-cooling/field-cooling measurements indicate that room temperature ferromagnetism in Co-doped TiO2 films is not an intrinsic property of the material. The presence of Co metal is identified by x-ray photoelectron spectroscopy and scanning electron microscopy.

  11. Crystal Structure and Photocatalytic Activity of Al-Doped TiO2 Nanofibers for Methylene Blue Dye Degradation.

    PubMed

    Lee, Deuk Yong; Lee, Myung-Hyun; Kim, Bae-Yeon; Cho, Nam-Ihn

    2016-05-01

    Al-TiO2 nanofibers were prepared using a sol-gel derived electrospinning by varying the Al/Ti molar ratio from 0 to 0.73 to investigate the effect of Al doping on the crystal structure and the photocatalytic activity of Al-TiO2 for methylene blue (MB) degradation. XRD results indicated that as the Al/Ti molar ratio rose, crystal structure of Al-TiO2 was changed from anatase/rutile (undoped), anatase (0.07-0.18), to amorphous phase (0.38-0.73), which was confirmed by XPS and Raman analysis. The degradation kinetic constant increased from 7.3 x 10(-4) min(-1) to 4.5 x 10(-3) min(-1) with the increase of Al/Ti molar ratios from 0 to 0.38, but decreased to 3.4 x 10(-3) min(-1) when the Al/Ti molar ratio reached 0.73. The Al-TiO2 catalyst doped with 0.38 Al/Ti molar ratio demonstrated the best MB degradation. Experimental results indicated that the Al doping in Al-TiO2 was mainly attributed to the crystal structure of TiO2 and the photocatalytic degradation of MB. PMID:27483928

  12. In Situ Fluorine Doping of TiO2 Superstructures for Efficient Visible-Light Driven Hydrogen Generation.

    PubMed

    Zhang, Peng; Tachikawa, Takashi; Fujitsuka, Mamoru; Majima, Tetsuro

    2016-03-21

    With the aid of breakthroughs in nanoscience and nanotechnology, it is imperative to develop metal oxide semiconductors through visible light-driven hydrogen generation. In this study, TiOF2 was incorporated as an n-type F-dopant source to TiO2 mesocrystals (TMCs) with visible-light absorption during the topotactic transformation. The crystal growth, structural change, and dynamic morphological evolution, from the initial intermediate NH4 TiOF3 to HTiOF3 , TiOF2 , and F-doped TMCs, were verified through in situ temperature-dependent techniques to elucidate the doping mechanism from intermediate TiOF2 . The visible-light efficiencies of photocatalytic hydrogen were dependent on the contents of the dopant as compared with the pure TMC and a controled reference. Using femtosecond time-resolved diffuse reflectance spectroscopy, the charge-transfer dynamics were monitored to confirm the improvement of charge separation after doping. PMID:26871554

  13. Phonon Dispersion, Electronic Structure and Photocatalytic Properties of Rutile TiO2 doped with X-doped (X =N, B and Pt)

    NASA Astrophysics Data System (ADS)

    Gupta, Sanjeev K.; Jha, Prafulla K.; Lukačević, Igor

    2013-03-01

    First principles calculations were performed on the electronic, vibrational and Raman spectra of substitutional N, B and Pt-doped rutile titanium dioxide (TiO2) , within the density functional theory (DFT), using the plane-wave pseudopotential method as implemented in the ABINIT package. Of all the photocatalytic materials TiO2 has been shown as the most useful one, with the most efficient photoactivity, the highest stability and the lowest cost. Moreover, it is safe for humans and the environment. The development of new types of photocatalytic cells is driven by the need for clean and sustainable energy. In this respect best doped materials are considered as a promising route for departing from the traditional photocatalytic cells. The physical insight provided by computational modeling may help in developing improved photocatalytic devices. To this end it is important to obtain an accurate description of the electronic structure and phonon dynamics, including the fundamental gaps and level alignment at the doped-TiO2 interface.

  14. N-doped P25 TiO2-amorphous Al2O3 composites: one-step solution combustion preparation and enhanced visible-light photocatalytic activity.

    PubMed

    Li, Fa-tang; Zhao, Ye; Hao, Ying-juan; Wang, Xiao-jing; Liu, Rui-hong; Zhao, Di-shun; Chen, Dai-mei

    2012-11-15

    Nitrogen-doped Degussa P25 TiO2-amorphous Al2O3 composites were prepared via facile solution combustion. The composites were characterised using X-ray diffraction, high-resolution transmission microscopy, scanning electron microscopy, nitrogen adsorption-desorption measurements, X-ray photoelectron spectroscopy, UV-vis light-diffusion reflectance spectrometry (DRS), zeta-potential measurements, and photoluminescence spectroscopy. The DRS results showed that TiO2 and amorphous Al2O3 exhibited absorption in the UV region. However, the Al2O3/TiO2 composite exhibited visible-light absorption, which was attributed to N-doping during high-temperature combustion and to alterations in the electronic structure of Ti species induced by the addition of Al. The optimal molar ratio of TiO2 to Al2O3 was 1.5:1, and this composite exhibited a large specific surface area of 152 m2/g, surface positive charges, and enhanced photocatalytic activity. These characteristics enhanced the degradation rate of anionic methylene orange, which was 43.6 times greater than that of pure P25 TiO2. The high visible-light photocatalytic activity was attributed to synthetic effects between amorphous Al2O3 and TiO2, low recombination efficiency of photo-excited electrons and holes, N-doping, and a large specific surface area. Experiments that involved radical scavengers indicated that OH and O2- were the main reactive species. A potential photocatalytic mechanism was also proposed. PMID:23021102

  15. The fabrication and characterization of novel carbon doped TiO2 nanotubes, nanowires and nanorods with high visible light photocatalytic activity.

    PubMed

    Wu, Zhongbiao; Dong, Fan; Zhao, Weirong; Wang, Haiqiang; Liu, Yue; Guan, Baohong

    2009-06-10

    Novel carbon doped TiO(2) nanotubes, nanowires and nanorods were fabricated by utilizing the nanoconfinement of hollow titanate nanotubes (TNTs). The fabrication process included adsorption of ethanol molecules in the inner space of TNTs and thermal treatment of the complex in inert N(2) atmosphere. The structural morphology of carbon doped TiO(2) nanostructures can be tuned using the calcination temperature. X-ray diffraction, Raman and Brunauer-Emmett-Teller studies proved that the doped carbon promoted the crystallization and phase transition by acting as nucleation seeds. X-ray photoelectron spectroscopy (XPS) showed that O-Ti-C and Ti-O-C bonds were formed in the nanostructures. Additional electronic states from the XPS valence band due to carbon doping were observed. This evidence indicated the electronic origin of the band gap narrowing and visible light absorption. The differences in chemical and electronic states between the surface and bulk of as-prepared samples confirmed that carbon was doped into the lattice of TiO(2) nanostructure through an inner doping process. The as-prepared catalysts exhibited enhanced photocatalytic activity for degradation of toluene in gas phase under both visible and simulated solar light irradiation compared with that of commercial Degussa P25. This novel fabrication approach can valuably contribute to designing nanostructured photocatalytic materials and modifying various nanotube materials. PMID:19451679

  16. 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

  17. Very low amount of TiO2 on N-doped carbon nanotubes significantly improves oxygen reduction activity and stability of supported Pt nanoparticles.

    PubMed

    Zhao, Anqi; Masa, Justus; Xia, Wei

    2015-04-28

    Electrochemical corrosion is a major problem for carbon materials used in electrocatalysis. Highly dispersed TiO2 was deposited on O-functionalized and N-doped carbon nanotubes by chemical vapour deposition to tackle the carbon corrosion problem. Very low Ti loadings of about 1 wt% were applied to minimize the negative influence of TiO2 as a semiconductor on the high conductivity of carbon materials. Both N doping and TiO2 coating facilitate strong metal-support interactions and favour the formation of small Pt particles. N doping improved the intrinsic catalytic activity of the carbon support and enhanced the conductivity due to the removal of surface oxygen groups, while the negative effect of TiO2 on conductivity is counterbalanced by its promoting effect on metal-support interactions leading to enhanced overall catalytic performance. Pt/TiO2/NCNTs showed the highest ORR activity, and significantly outperformed Pt/NCNTs in electrochemical stability tests. PMID:25811122

  18. Solid-state NMR and EPR analysis of carbon-doped titanium dioxide photocatalysts (TiO(2-)(x)C(x)).

    PubMed

    Reyes-Garcia, Enrique A; Sun, Yanping; Reyes-Gil, Karla R; Raftery, Daniel

    2009-04-01

    Carbon-doped TiO(2) have received attention recently because of their potential for environmental photocatalysis and solar hydrogen conversion applications. Three different carbon-doped TiO(2) nanoparticle materials were synthesized via sol-gel and hydrothermal procedures, and analyzed by (13)C solid-state nuclear magnetic resonance (SSNMR) and other methods to characterize the environment of the doping species. UV/vis spectra and powder X-ray diffraction (XRD) patterns showed that the synthesized materials absorbed visible light and their crystal structures corresponded to anatase. (13)C SSNMR analyses of TiO(2-)(x)C(x) displayed signals corresponding to carbonate-type or sp(2)-type carbon species. Variable contact CP-MAS and dipolar dephasing analyses gave evidence for the presence and proximity of H atoms near these carbonate species. Electron paramagnetic resonance (EPR) spectroscopy showed that the thermally oxidized TiO(2-)(x)C(x) displayed a complex mixture of point defects, electron and hole trapping centers, all attributable to the incorporation of carbon, while the XPS data ruled out the presence of carbide species. PMID:19307109

  19. Effect of Nb-doped TiO2 on nanocomposited aligned ZnO nanorod/TiO2:Nb for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Saurdi, I.; Shafura, A. K.; Azhar, N. E. A.; Ishak, A.; Malek, M. F.; Alrokayan, A. H. Salman; Khan, Haseeb A.; Mamat, M. H.; Rusop, M.

    2016-07-01

    The Nb-doped TiO2 films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO2 films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO2 (TiO2:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO2:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO2:Nb-5at.%.

  20. Ultrasmall TiO2 nanoparticles embedded in nitrogen doped porous graphene for high rate and long life lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Qin, Guohui; Zhang, Hongjuan; Wang, Chengyang

    2014-12-01

    Modifying TiO2 with nitrogen and porous N doped graphene to form mesoporous TiO2/N doped graphene nanostuctures has been successfully achieved by a two-step hydrothermal-calcining method with urea as an inhibitor and nitrogen source. Porous N doped graphene network hinders the agglomeration of TiO2 nanoparticles, and enhances the conductivity of TiO2 based electrode simultaneously, achieving the enhanced capacity and fast discharge and charge rate. As a anode material, such nanocomposite exhibits a capacity as high as 330.7 mAh g-1at a current rate of 0.5 C and a reversible capacity over 288.6 mAh g-1 accompanying a coulombic efficiency of 96.4% at a current rate of 30 C after 1000 cycles. The superior electrochemical performance is ascribed to the excellent rate performance and cycling stability, moreover, highly exciting from a fundamental point of view, the good electronic conductivity caused by N incorporated graphene sheets and the positive synergistic effect between ultrafined nanoparticles and porous N decorated graphene matrix. Additionally, the restriction to ultrasmall reaction domains with high specific surface area and mesoporous structure allowing for an almost diffusion less and nucleation-free "conversion" results in highly efficient lithium ion batteries with fast charge/discharge rate and a remarkably enhanced cycling performance.

  1. Three-dimensional ruthenium-doped TiO2 sea urchins for enhanced visible-light-responsive H2 production.

    PubMed

    Nguyen-Phan, Thuy-Duong; Luo, Si; Vovchok, Dimitriy; Llorca, Jordi; Sallis, Shawn; Kattel, Shyam; Xu, Wenqian; Piper, Louis F J; Polyansky, Dmitry E; Senanayake, Sanjaya D; Stacchiola, Dario J; Rodriguez, José A

    2016-06-21

    Three-dimensional (3D) monodispersed sea urchin-like Ru-doped rutile TiO2 hierarchical architectures composed of radially aligned, densely-packed TiO2 nanorods have been successfully synthesized via an acid-hydrothermal method at low temperature without the assistance of any structure-directing agent and post annealing treatment. The addition of a minuscule concentration of ruthenium dopants remarkably catalyzes the formation of the 3D urchin structure and drives the enhanced photocatalytic H2 production under visible light irradiation, not possible on undoped and bulk rutile TiO2. Increasing ruthenium doping dosage not only increases the surface area up to 166 m(2) g(-1) but also induces enhanced photoresponse in the regime of visible and near infrared light. The doping introduces defect impurity levels, i.e. oxygen vacancy and under-coordinated Ti(3+), significantly below the conduction band of TiO2, and ruthenium species act as electron donors/acceptors that accelerate the photogenerated hole and electron transfer and efficiently suppress the rapid charge recombination, therefore improving the visible-light-driven activity. PMID:27240884

  2. Gas Sensitivity and Sensing Mechanism Studies on Au-Doped TiO2 Nanotube Arrays for Detecting SF6 Decomposed Components

    PubMed Central

    Zhang, Xiaoxing; Yu, Lei; Tie, Jing; Dong, Xingchen

    2014-01-01

    The analysis to SF6 decomposed component gases is an efficient diagnostic approach to detect the partial discharge in gas-insulated switchgear (GIS) for the purpose of accessing the operating state of power equipment. This paper applied the Au-doped TiO2 nanotube array sensor (Au-TiO2 NTAs) to detect SF6 decomposed components. The electrochemical constant potential method was adopted in the Au-TiO2 NTAs' fabrication, and a series of experiments were conducted to test the characteristic SF6 decomposed gases for a thorough investigation of sensing performances. The sensing characteristic curves of intrinsic and Au-doped TiO2 NTAs were compared to study the mechanism of the gas sensing response. The results indicated that the doped Au could change the TiO2 nanotube arrays' performances of gas sensing selectivity in SF6 decomposed components, as well as reducing the working temperature of TiO2 NTAs. PMID:25330053

  3. Photooxidation of different organic dyes (RB, MO, TB, and BG) using Fe(III)-doped TiO 2 nanophotocatalyst prepared by novel chemical method

    NASA Astrophysics Data System (ADS)

    Ghorai, Tanmay K.; Biswas, Soumya K.; Pramanik, Panchanan

    2008-09-01

    The nano-structured Fe(III)-doped TiO 2 photocatalysts with anatase phase have been developed for the oxidation of non-biodegradable different organic dyes like methyl orange (MO), rhodamine B (RB), thymol blue (TB) and bromocresol green (BG) using UV-Hg-lamp. The different compositions of Fe xTi 1- xO 2 ( x = 0.005, 0.01, 0.05, and 0.1) nanocatalysts synthesized by chemical method (CM), have been characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, specific surface area (BET), transmission electronic microscopy (TEM) analysis, XPS, ESR and zeta potential. From XRD analysis, the results indicate that all the compositions of Fe(III) doped in TiO 2 catalysts gives only anatase phase not rutile phase. For complete degradation of all the solutions of the dyes (MO, RB, TB, and BG), the composition with x = 0.005 is more photoactive compared all other compositions of Fe xTi 1- xO 2, and degussa P25. The decolorization rate of different dyes decreases as Fe(III) concentration in TiO 2 increases. The energy band gap of Fe(III)-doped TiO 2 is found to be 2.38 eV. The oxidation state of iron has been found to be 3+ from XPS and ESR show that Fe 3+ is in low spin state.

  4. Doped TiO2 anodic layers of enhanced antibacterial properties.

    PubMed

    Arenas, María A; Pérez-Jorge, Concepción; Conde, Ana; Matykina, Endzhe; Hernández-López, Juan M; Pérez-Tanoira, Ramón; de Damborenea, Juan J; Gómez-Barrena, Enrique; Esteba, Jaime

    2013-05-01

    Ti-6Al-4V joint replacement implants foster uncemented fixation in orthopaedic surgery. However, bacterial colonization competes with host cells and ultimately may produce implant-related difficult-to-treat infections, justifying the efforts to obtain infection-resistant materials. In a previous work, the authors demonstrated the antibacterial properties of anodic fluoride-TiO2 nanostructured layers on Ti-6Al-4V alloy. In this work, the anodizing bath has been modified in order to grow fluoride-TiO2 barrier layers (FBL). A bacterial adherence protocol, run with reference and six different clinical strains of Staphylococcus aureus and Staphylococcus epidermidis, showed a statistically significant decrease in the percentage of covered surface (p<0.0001, Kruskal-Wallis test) for FBL specimens when compared with non fluoride-containing specimens, i.e. chemically polished Ti-6Al-4V and F-free TiO2 barrier layers. The results obtained on the F-barrier layers allowed discrimination between the effects of the presence of fluoride in the layer and the layer nanostructure on bacterial adhesion. PMID:23357736

  5. Photocatalytic characteristic and photodegradation kinetics of toluene using N-doped TiO2 modified by radio frequency plasma.

    PubMed

    Shie, Je-Lueng; Lee, Chiu-Hsuan; Chiou, Chyow-San; Chen, Yi-Hung; Chang, Ching-Yuan

    2014-01-01

    This study investigates the feasibility of applications of the plasma surface modification of photocatalysts and the removal of toluene from indoor environments. N-doped TiO2 is prepared by precipitation methods and calcined using a muffle furnace (MF) and modified by radio frequency plasma (RF) at different temperatures with light sources from a visible light lamp (VLL), a white light-emitting diode (WLED) and an ultraviolet light-emitting diode (UVLED). The operation parameters and influential factors are addressed and prepared for characteristic analysis and photo-decomposition examination. Furthermore, related kinetic models are established and used to simulate the experimental data. The characteristic analysis results show that the RF plasma-calcination method enhanced the Brunauer Emmett Teller surface area of the modified photocatalysts effectively. For the elemental analysis, the mass percentages of N for the RF-modified photocatalyst are larger than those of MF by six times. The aerodynamic diameters of the RF-modifiedphotocatalyst are all smaller than those of MF. Photocatalytic decompositions of toluene are elucidated according to the Langmuir-Hinshelwood model. Decomposition efficiencies (eta) of toluene for RF-calcined methods are all higher than those of commercial TiO2 (P25). Reaction kinetics ofphoto-decomposition reactions using RF-calcined methods with WLED are proposed. A comparison of the simulation results with experimental data is also made and indicates good agreement. All the results provide useful information and design specifications. Thus, this study shows the feasibility and potential use of plasma modification via LED in photocatalysis. PMID:24645445

  6. Catalysis under Cover: Enhanced Reactivity at the Interface between (Doped) Graphene and Anatase TiO2.

    PubMed

    Ferrighi, Lara; Datteo, Martina; Fazio, Gianluca; Di Valentin, Cristiana

    2016-06-15

    The "catalysis under cover" involves chemical processes which take place in the confined zone between a 2D material, such as graphene, h-BN, or MoS2, and the surface of an underlying support, such as a metal or a semiconducting oxide. The hybrid interface between graphene and anatase TiO2 is extremely important for photocatalytic and catalytic applications because of the excellent and complementary properties of the two materials. We investigate and discuss the reactivity of O2 and H2O on top and at the interface of this hybrid system by means of a wide set of dispersion-corrected hybrid density functional calculations. Both pure and boron- or nitrogen-doped graphene are interfaced with the most stable (101) anatase surface of TiO2 in order to improve the chemical activity of the C-layer. Especially in the case of boron, an enhanced reactivity toward O2 dissociation is observed as a result of both the contribution of the dopant and of the confinement effect in the bidimensional area between the two surfaces. Extremely stable dissociation products are observed where the boron atom bridges the two systems by forming very stable B-O covalent bonds. Interestingly, the B defect in graphene could also act as the transfer channel of oxygen atoms from the top side across the C atomic layer into the G/TiO2 interface. On the contrary, the same conditions are not found to favor water dissociation, proving that the "catalysis under cover" is not a general effect, but rather highly depends on the interfacing material properties, on the presence of defects and impurities and on the specific reaction involved. PMID:27203544

  7. Synthesize and characterize of Ag3VO4/TiO2 nanorods photocatalysts and its photocatalytic activity under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Zou, Xuejun; Dong, Yuying; Zhang, Xiaodong; Cui, Yubo

    2016-03-01

    In this paper, in order to expand the light response range of TiO2, Ag3VO4/TiO2 nanorods photocatalysts were fabricated by a simple sol-gel method with microwave and hydrothermal method. The as-prepared samples were characterized by XRD, SEM, DRS, XPS and N2 adsorption-desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of toluene under visible light irradiation. The degradation conversation of toluene had gotten to about 70% in 1% Ag3VO4/TiO2 nanorods after reaction 4 h. The predominant photocatalytic activity can be attributed to its strong absorption in visible light region and excellent charge separation characteristics. By using in situ FTIR, benzyl alcohol and benzaldehyde species could be observed during the reaction and the formed intermediates would be partially oxidized into CO2 and H2O. Electron spin resonance confirmed that OHrad and O2rad - were involved in the photocatalytic degradation of toluene.

  8. Multi-functional TiO2/Si/Ag(Cr)/TiNx coatings for low-emissivity and hydrophilic applications

    NASA Astrophysics Data System (ADS)

    Loka, Chadrasekhar; Park, Kyoung Ryeol; Lee, Kee-Sun

    2016-02-01

    Multi-functional (coatings with some additional functional properties such as high transparency, antireflection, hydrophilicity and antifogging) coatings are indispensable for the modern energy saving systems. In this regard, we deposited TiO2/Si/Ag(Cr)/TiNx multilayer thin films on soda-lime glass by using RF and DC magnetron sputtering to achieve a multi-functional thin film stack with the combination low-emissivity (low-e) and hydrophilicity properties in addition to the high transparency. Primary deposition of Ag(Cr)/TiNx was tried for the low-e effect and successfully obtained a very low emissivity value of 0.067, and then Si and TiO2 films with different bandgap were subsequently deposited to provide the hydrophilic properties. X-ray diffraction results revealed the anatase phase formation of TiO2 after annealing the films at 673 K by using the rapid thermal annealing system. Rutherford Backscattering Spectrometry (RBS) was carried out to determine the chemical composition and elemental depth distribution. The multilayer stack exhibited superhydrophilicity with a water contact angle of about 5° after irradiation by UV light. A Heterojunction film with wide and narrow bandgap semiconductor materials was effective to improve the hydrophilicity. The films exhibited a high visible transmittance (∼85.5%, at 550 nm) and low infrared transmittance (7%, at 2000 nm) including low-e and superhydrophilicity.

  9. Removal of elemental mercury by TiO2doped with WO3 and V2O5 for their photo- and thermo-catalytic removal mechanisms.

    PubMed

    Shen, Huazhen; Ie, Iau-Ren; Yuan, Chung-Shin; Hung, Chung-Hsuang; Chen, Wei-Hsiang

    2016-03-01

    The catalytic removal of Hg(0) was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V2O5/TiO2 and WO3/TiO2 catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg(0). They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100-160 °C under the near-UV irradiation. The results indicated that V2O5/TiO2 solely possessed the thermo-catalytic reactivity while WO3/TiO2 only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO2, the removal efficiencies of Hg(0) at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO2 to nearly 90 % by WO3/TiO2 under the same operating conditions. The effects of doping amount of V2O5 and WO3 were also investigated, and the results showed that 10 % V2O5 and 5 % WO3/TiO2 were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg(0) was demonstrated that the highest concentration of Hg(0) led to the best removal efficiencies for V2O5/TiO2 and WO3/TiO2 at 140 and 160 °C, because high Hg(0) concentration increased the mass transfer rate of Hg(0) toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg(0) was also investigated. PMID:26590063

  10. CeO2 doped anatase TiO2 with exposed (001) high energy facets and its performance in selective catalytic reduction of NO by NH3

    NASA Astrophysics Data System (ADS)

    Wang, Haiqiang; Cao, Shuang; Fang, Zheng; Yu, Feixiang; Liu, Yue; Weng, Xiaole; Wu, Zhongbiao

    2015-03-01

    Ceria doped on anatase TiO2 with high energy (001) facets was synthesized in this paper, which was subsequently utilized for selective catalytic reduction (SCR) of NO by NH3. After subjected to a range of analytical techniques, such as XRD, BET, TEM, XPS ESR, H2-TPR and NH3-TPD, it was found that compared with Ce/P25 catalyst, the presence of (001) facets over the TiO2 support had yielded a remarkably high activity at 390-490 °C for NO removal. The unique feature of active-energy (001) facets had enhanced the thermal stability of CeO2 whilst the presence of Ti3+ over the TiO2 surface had effectively facilitated the SCR process, both of which resulted in the remarkable catalytic performance for the catalyst.

  11. Influence of calcination parameters on the synthesis of N-doped TiO2 by the polymeric precursors method

    NASA Astrophysics Data System (ADS)

    Dawson, Margaret; Soares, Gabriela Byzynski; Ribeiro, Caue

    2014-07-01

    In this paper, the influence of calcination parameters on the synthesis of N:TiO2 catalysts obtained through the polymeric precursors method was evaluated. The powders were prepared by annealing Ti4+ precursor resins at different temperature-time conditions in air, resulting in powders with different degrees of crystallinity for N doping, which was done by adding urea to the as-prepared powders and calcining in N2 atmosphere. The N doping process resulted in band gap narrowing of TiO2 and, varying annealing temperature and time, can be an alternative method for preferential formation of substitutional N or interstitial N. It was found that the percentage of interstitial N increased with an increase in annealing temperature, resulting in the complete absence of substitutional N at 400 °C. The photocatalytic performance of the powders was evaluated using Rhodamine-B and Atrazine solutions under ultraviolet and visible irradiations. The coefficients revealed that interstitial N had a positive correlation to both ultraviolet and visible photoactivity. In contrast, substitutional N showed a negative correlation. Further, the ratio of substitutional N to interstitial N indicated a strong negative correlation to ultraviolet light photoactivity and no correlation to visible light photoactivity. However, substitutional N should be controlled for better photocatalytic properties.

  12. Enhancement of photocatalytic properties of TiO2 nanoparticles doped with CeO2 and supported on SiO2 for phenol degradation

    NASA Astrophysics Data System (ADS)

    Hao, Chunjing; Li, Jing; Zhang, Zailei; Ji, Yongjun; Zhan, Hanhui; Xiao, Fangxing; Wang, Dan; Liu, Bin; Su, Fabing

    2015-03-01

    A series of CeO2-TiO2 and CeO2-TiO2/SiO2 composites were prepared with TiCl4 and Ce (NO3)3·6H2O as precursors via a facile co-precipitation method. The obtained samples were characterized by various techniques such as X-ray diffraction (XRD), nitrogen adsorption (N2-BET), Fourier transformation infrared spectrum (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis spectroscopy measurements. The results indicated that TiO2 doped with CeO2 and supported on SiO2 could reduce the crystallite size, inhibit the phase transformation, enhance the thermal stability, and effectively extend the spectral response from UV to visible range. When applied to the phenol photodegradation on a homemade batch reactor with an external cooling jacket, the CeO2-TiO2/SiO2 catalysts exhibited significantly enhanced photodegradation efficiency in comparison with commercial Degussa P25 and CeO2-TiO2. The unique catalytic properties of CeO2-TiO2/SiO2 were ascribed to improved electron-hole pairs separation efficiency and formation of more reactive oxygen species owing to the presence of Ce3+/Ce4+, as well as high dispersion of active component of CeO2-TiO2 as a result of the introduction of SiO2 support. Furthermore, the catalysts can be easily recovered from the reaction solution by centrifugation and reused for four cycles without significant loss of activity.

  13. Preparation of TiO2/boron-doped diamond/Ta multilayer films and use as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Shi, Chao; Li, Hongji; Li, Cuiping; Li, Mingji; Qu, Changqing; Yang, Baohe

    2015-12-01

    We report nanostructured TiO2/boron-doped diamond (BDD)/Ta multilayer films and their electrochemical performances as supercapacitor electrodes. The BDD films were grown on Ta substrates using electron-assisted hot filament chemical vapor deposition. Ti metal layers were deposited on the BDD surfaces by radio frequency magnetron sputtering, and nanostructured TiO2/BDD/Ta thin films were prepared by electrochemical etching and thermal annealing. The successful formation of TiO2 and Ta layered nanostructures was demonstrated using scanning electron and transmission electron microscopies. The electrochemical responses of these electrodes were evaluated by examining their use as electrical double-layer capacitors, using cyclic voltammetry, and galvanostatic charge/discharge and impedance measurements. When the TiO2/BDD/Ta film was used as the working electrode with 0.1 M Na2SO4 as the electrolyte, the capacitor had a specific capacitance of 5.23 mF cm-2 at a scan rate of 5 mV s-1 for a B/C ratio of 0.1% w/w. Furthermore, the TiO2/BDD/Ta film had improved electrochemical stability, with a retention of 89.3% after 500 cycles. This electrochemical behavior is attributed to the quality of the BDD, the surface roughness and electrocatalytic activities of the TiO2 layer and Ta nanoporous structures, and the synergies between them. These results show that TiO2/BDD/Ta films are promising as capacitor electrodes for special applications.

  14. Titanium atoms dimerization phenomenon and magnetic properties of titanium-antisite (TiO) and chromium doped rutile TiO2, ab-initio calculation

    NASA Astrophysics Data System (ADS)

    Zarhri, Z.; Ziat, Y.; El Rhazouani, O.; Benyoussef, A.; Elkenz, A.

    2016-07-01

    The ab-initio calculations based on the Korringa Kohn Rostoker approximation approach combined with coherent potential approximation (KKR-CPA), were used to study the magnetic properties of the titanium anti-site (TiO) and chromium (Cr) doped TiO2. In the considered systems, we used different concentrations for TiO defect and Cr doping. In TiO2(0.98)(TiO)0.02, the obtained results indicate that TiO is a donor having half-metal behavior. TiO[3d] band is located at the Fermi level, although isn't 100% polarized, the ferromagnetic (FM) state is verified as being more stable than disordered local moment (DLM) state. For Ti0.98Cr0.02O2 the Cr doping introduced new states which give the material half-metallic feature. The majority spin of Cr impurities are located at the Fermi level and the conduction electrons around the Fermi level are 100% spin polarized. This indicates the stability of (FM) state. Moreover, in Ti0.98Cr0.02O2(0.98)(TiO)0.02, the top of the valence band is shifted to lower energy compared to pure TiO2, and the n-type of TiO2 is verified. The majority spin of Cr[3d] are located at 0.025 Ry close to the Fermi level. The predicted Curie temperatures (Tc) were calculated using the mean field approximation (MFA) and we predicted that TiO defect in Cr doped TiO2 makes Tc higher. This kind of defect makes the material useful for spinotronics's applications and devices.

  15. Low temperature synthesis of N-doped TiO2 with rice-like morphology through peroxo assisted hydrothermal route: Materials characterization and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Bakar, Shahzad Abu; Ribeiro, Caue

    2016-07-01

    Nanorice-shaped N:TiO2 photocatalysts have been prepared by the peroxo assisted hydrothermal method using stabilized titanium complex as a precursor and urea as a N source. The N:TiO2 nanorices were characterised by XRD, FE-SEM, HRTEM, XPS, UV-vis spectroscopy, Raman spectroscopy and measurements of photocatalytic degradation of organic molecules (atrazine and RhB dye) under the UV and visible-light irradiation. XRD analyses showed that pristine TiO2 crystallizes into anatase polymorph and that the N-doping process at 5% introduced a degree of disorder on the TiO2 crystalline structure. XPS study revealed the successful incorporation of the nitrogen atoms at the interstitial sites of the TiO2 crystal lattice. Microscopy studies revealed that the particle size was in the range 50-80 nm for the pristine TiO2. The photocatalysts were assembled in the form of nanorices with a high surface area (102 m2 g-1). The successful incorporation of nitrogen atoms into the TiO2 crystal lattice is expected to be responsible for enhanced photocatalytic activity of the as-prepared samples for the degradation of pollutants (RhB and atrazine) under UV and visible light irradiation. The rate of rad OH radicals formation under visible-light irradiation was examined and found to be correlated with the photocatalytic activity per unit surface area. The N:TiO2 particles with nanorice morphology was efficient photocatalysts for decomposition of organic dyes under UV and visible-light exposure while pristine TiO2 photocatalyst did not show any significant photocatalytic activity when stimulated by visible-light. The 3% doped N:TiO2 sample exhibited the highest photocatalytic activity among all synthesized photocatalysts.

  16. Multivalence Charge Transfer in Doped and Codoped Photocatalytic TiO2.

    PubMed

    Ren, Hangjuan; Koshy, Pramod; Cao, Fuyang; Sorrell, Charles Christopher

    2016-08-15

    The present work reports data for the mineralogical and chemical properties of anatase thin films individually doped or codoped with chromium and vanadium, fabricated by sol-gel spin coating on glass substrates and annealing at 450 °C for 2 h. X-ray photoelectron spectroscopy data indicated the presence of Ti(4+), Ti(3+), Cr(3+), and possibly Cr(4+) in the Cr-doped thin films; Ti(4+), Ti(3+), V(3+), V(4+), and possibly V(5+) in the V-doped thin films; and Ti(4+), Ti(3+), Cr(3+), Cr(4+), V(3+), V(4+), and possibly V(5+) in the codoped thin films. While the thermodynamically stable valences Ti(4+), Cr(3+), and V(5+) would be expected to have formed, the presence of the nonequilibrium valences Ti(3+), Cr(4+), V(3+), and V(4+) is considered to have resulted from intervalence charge transfer for the Cr-doped and V-doped systems but from multivalence charge transfer (MVCT) for the codoped system. The latter phenomenon, which is introduced as a new conceptual term, describes the nature of the mutual exchange of electrons during valence changes of both dopant (Cr, V) and matrix (Ti) ions during annealing. In the present case, MVCT appears to be a transient metastable condition that acts during annealing, but subsequent UV irradiation can alter its effects. PMID:27487225

  17. Multifunctional Ag-decorated porous TiO2 nanofibers in dye-sensitized solar cells: efficient light harvesting, light scattering, and electrolyte contact.

    PubMed

    Hwang, Sun Hye; Song, Hee; Lee, Jungsup; Jang, Jyongsik

    2014-09-26

    Designing the photoanode structure in dye-sensitized solar cells (DSSCs) is vital to realizing enhanced power conversion efficiency (PCE). Herein, novel multifunctional silver-decorated porous titanium dioxide nanofibers (Ag/pTiO2 NFs) made by simple electrospinning, etching, and chemical reduction processes are introduced. The Ag/pTiO2 NFs with a high surface area of 163 m(2)  g(-1) provided sufficient dye adsorption for light harvesting. Moreover, the approximately 200 nm diameter and rough surface of the Ag/pTiO2 NFs offered enough light scattering, and the enlarged interpores among the NFs in the photoanode also permitted electrolyte circulation. Ag nanoparticles (NPs) were well dispersed on the surface of the TiO2 NFs, which prevented aggregation of the Ag NPs after calcination. Furthermore, a localized surface plasmon resonance effect by the Ag NPs served to increase the light absorption at visible wavelengths. The surface area and amount of Ag NPs was optimized. The PCE of pTiO2 NF-based DSSCs was 27 % higher (from 6.2 to 7.9 %) than for pure TiO2 NFs, whereas the PCE of Ag/pTiO2 NF-based DSSCs increased by about 12 % (from 7.9 to 8.8 %). Thus, the PCE of the multifunctional pTiO2 NFs was improved by 42 %, that is, from 6.2 to 8.8 %. PMID:25138442

  18. Visible Light Absorption of N-Doped TiO2 Rutile Using (LR/RT)-TDDFT and Active Space EOMCCSD Calculations

    SciTech Connect

    Govind, Niranjan; Lopata, Kenneth A.; Rousseau, Roger J.; Andersen, Amity; Kowalski, Karol

    2011-11-03

    We have performed detailed ground and excited state calculations of pure and N-doped TiO2 rutile to model and analyze the experimentally observed UV/Vis spectrum. Using our embedding model we have performed both linear-response (LR) and real-time (RT) TDDFT calculations of the excited states of the pure and N-doped systems. We have also studied the lowest excitations using high-level active space equation-of-motion coupled cluster (EOMCC) approaches involving all single and inter-band double excitations. We compare and contrast the nature of the excitations in detail for the pure and doped systems and also provide an analysis of the excited-state density using our RT-TDDFT calculations. Our calculations indicate a lowering of the band gap and verify the role of the N3- states on the observed spectrum of N-doped TiO2 rutile as suggested by experimental findings. Both RT-TDDFT and EOMCC calculations show that the excitations in pure TiO2 are more delocalized compared with the N-doped system.

  19. Photovoltaic performances of Cu2-xTe sensitizer based on undoped and indium(3+)-doped TiO2 photoelectrodes and assembled counter electrodes.

    PubMed

    Srathongluan, Pornpimol; Kuhamaneechot, Rattanakorn; Sukthao, Prapatsawan; Vailikhit, Veeramol; Choopun, Supab; Tubtimtae, Auttasit

    2016-02-01

    Novel binary Cu2-xTe nanoparticles based on undoped and indium-doped TiO2 photoelectrodes were synthesized using a successive ionic layer adsorption and reaction (SILAR) technique as a sensitizer for liquid-junction solar cells. A larger diameter of TiO2 promoted a narrower energy band gap after indium doping, attributing to yield a broader absorption range of nanoparticle sensitizer due to the increasing amount of Cu2-xTe NPs on TiO2 surface. The atomic percentages showed the stoichiometric formation of Cu2Te incorporated in a Cu2-xTe structure. The best photovoltaic performance with the lower SILAR cycle, i.e., n=13 was performed after indium doping in both of carbon and Cu2S CEs and revealed that the efficiency of 0.73% under the radiant 100mW/cm(2) (AM 1.5G). The electrochemical impedance spectroscopy (EIS) was used to investigate the electrical properties via effect of material doping and counter electrodes with a lower charge-transfer resistance (Rct) and it was also found that the electron lifetime was improved after the sample doped with indium and assembled with carbon CE. PMID:26524258

  20. Preparation and characterization of mesoporous N-doped and sulfuric acid treated anatase TiO 2 catalysts and their photocatalytic activity under UV and Vis illumination

    NASA Astrophysics Data System (ADS)

    Kun, Robert; Tarján, Sándor; Oszkó, Albert; Seemann, Torben; Zöllmer, Volker; Busse, Matthias; Dékány, Imre

    2009-11-01

    Nitrogen-doped TiO 2 catalysts were prepared by a precipitation method. The samples were calcined at 400 °C for 4 h in air. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature N 2-adsorption was used for structural characterization and UV-diffuse reflectance (UV-DR) was applied to investigate the optical properties of the as-prepared samples. It was found that microporous N-doped catalysts have solely anatase crystalline structure. Acidic treatment of the calcined samples was performed using sulfuric acid agitation. The crystalline structure remained unchanged due to surface treatment, while the porosity and the surface areas (aBETS) were decreased dramatically. Optical characterization of the doped catalysts showed that they could be excited by visible light photons in the 400-500 nm wavelength range ( λ g,1=˜390 nm, λ g,2=˜510 nm). It was also established that surface treatment enhances the Vis-light absorption of the N-TiO 2 powders. Finally the catalysts were tested in the photocatalytic degradation of phenol in aqueous suspensions. Two different light sources were used; one of them was a UV-rich high pressure Hg-lamp, while the other was a tubular visible light source. We found that using visible light illumination N-doped, acid treated TiO 2 samples were more catalytically active than non-doped TiO 2 catalysts.

  1. Porous immobilized C coated N doped TiO2 containing in-situ generated polyenes for enhanced visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sabri, N. A.; Nawi, M. A.; Nawawi, W. I.

    2015-10-01

    Carbon coated nitrogen-doped Degussa P25TiO2 (or C,N-P25TiO2) was successfully immobilized on a glass plate using epoxidized natural rubber (ENR-50) and polyvinyl chloride (PVC) as the organic binders. Photo-etching of the fabricated system for 10 h oxidized its PVC binder into polyenes as well as forming a highly porous surface. The band gap energy (Eg) of the photo-etched immobilized photocatalyst system (C,N-P25TiO2/ENR/PVC-10 h) was reduced from 2.91 to 2.86 eV. Its photocatalytic activity was studied via photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under a 45 W visible light fluorescent lamp. C,N-P25TiO2/ENR/PVC-10 h with polyenes performed better than its slurry counterpart under visible light irradiation where the conjugated double bonds acted as photo sensitizers. The immobilized C,N-P25TiO2/ENR/PVC-10 h has excellent reusability and sustainable with an average k value of 0.056 ± 0.011 min-1 and average percent removal of 99.18 ± 0.54%.

  2. Synthesis and characterization of anionic/nonionic surfactant-interceded iron-doped TiO2 to enhance sorbent/photo-catalytic properties

    NASA Astrophysics Data System (ADS)

    Sharma, Ajit; Lee, Byeong-Kyu

    2015-09-01

    We investigated the synthesis, characterization, and application of surfactant-interceded Fe nanoparticle-doped TiO2 (TiO2/Fe-S1 and TiO2/Fe-S2) that were used as adsorbents and photo-catalysts for the removal of As(V) ions from aqueous media. Two types of surfactant (anionic (sodium dodecyl sulfate), S1 and non-ionic (Triton X-100), S2) were used to obtain the separation and mono-dispersion of Fe(III) ions in the reaction solution. The nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and elemental mapping analysis before and after As(V) removal. The Langmuir capacities (qe, mg/g) of the sodium dodecyl sulfate (SDS) and Triton X-100 interceded nanocomposites (TiO2/Fe-S1 and TiO2/Fe-S2, respectively) for arsenic removal were determined to be 65.79 and 50.76 mg/g, respectively, in aqueous media with As(V) concentration ranges of 0-10 mg/L at pH 6.5.

  3. Performance enhancement of perovskite solar cells with Mg-doped TiO2 compact film as the hole-blocking layer

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Qin, Minchao; Tao, Hong; Ke, Weijun; Chen, Zhao; Wan, Jiawei; Qin, Pingli; Xiong, Liangbin; Lei, Hongwei; Yu, Huaqing; Fang, Guojia

    2015-03-01

    In this letter, we report perovskite solar cells with thin dense Mg-doped TiO2 as hole-blocking layers (HBLs), which outperform cells using TiO2 HBLs in several ways: higher open-circuit voltage (Voc) (1.08 V), power conversion efficiency (12.28%), short-circuit current, and fill factor. These properties improvements are attributed to the better properties of Mg-modulated TiO2 as compared to TiO2 such as better optical transmission properties, upshifted conduction band minimum (CBM) and downshifted valence band maximum (VBM), better hole-blocking effect, and higher electron life time. The higher-lying CBM due to the modulation with wider band gap MgO and the formation of magnesium oxide and magnesium hydroxides together resulted in an increment of Voc. In addition, the Mg-modulated TiO2 with lower VBM played a better role in the hole-blocking. The HBL with modulated band position provided better electron transport and hole blocking effects within the device.

  4. Application of a hybrid system comprising carbon-doped TiO2 film and a ceramic media-packed biofilter for enhanced removal of gaseous styrene.

    PubMed

    Kim, Moon-Sun; Liu, Gang; Cho, Hong-Kwan; Kim, Byung-Woo

    2011-06-15

    It is difficult to efficiently remove gaseous styrene using a TiO(2) film-coated photoreactor under UV light. Therefore, we used a hybrid system consisting of a carbon-doped TiO(2) (C-TiO(2)) film and a media-packed biofilter in order to enhance the removal efficiency (RE) of gaseous styrene compared to that of a pure (undoped) TiO(2) photoreactor. The C-TiO(2) was synthesized by a sol-gel combustion method, and its absorption spectrum was stronger that of pure (undoped) TiO(2) in the UV-vis range. The resultant RE of the C-TiO(2) film was 113-200% higher than that of the pure TiO(2) film. The initial RE of the photoreactor for input styrene concentrations of 630 mg m(-3), 420 mg m(-3), and 105 mg m(-3) was 20.6%, 29.8%, and 40.0%, respectively. When the biofilter was added, the RE increased to 93.3%, 97.9%, and 99.0%, respectively. Thus, application of the hybrid system consisting of both a photoreactor coated with a C-TiO(2) film and a biofilter is advantageous in terms of the removal efficiency of gaseous styrene. PMID:21501925

  5. Kinetic study of formic acid degradation by Fe3+ doped TiO2 self-cleaning nanostructure surfaces prepared by cold spray

    NASA Astrophysics Data System (ADS)

    Sayyar, Zahra; Akbar Babaluo, Ali; Shahrouzi, Javad Rahbar

    2015-04-01

    A self-cleaning solution was introduced in this paper based on sol-gel and was applied for preparing self-cleaning TiO2. Fe3+ ions have been doped into the TiO2 crystal lattice. XRD analysis indicated that the obtained TiO2 powder contains mainly the anatase phase and TiO2 powder has a crystallite size distribution of 10-12 nm. SEM micrographs have also confirmed nanometric distribution of the obtained powder. A series of uniform and transparent TiO2 and Fe/TiO2 films were prepared by cold spray technique which may result in high uniformity in the final coated surfaces. Photocatalytic activity of the thin films was investigated through degradation of aqueous formic acid under UV-visible light. The Langmuir-Hinshelwood kinetic model was used to interpret quantitatively the observed kinetic experimental result. Comparative study of the obtained coated surfaces with those of uncoated surfaces, demonstrated a remarkable performance. The Fe/TiO2 films and their calcination at 650 °C demonstrated the highest photocatalytic activity.

  6. A comparison of the characteristics of nanosecond, picosecond and femtosecond lasers generated Ag, TiO2 and Au nanoparticles in deionised water

    NASA Astrophysics Data System (ADS)

    Hamad, Abubaker; Li, Lin; Liu, Zhu

    2015-09-01

    Although there have been large quantities of published work in laser generation of nanoparticles, it is still unclear on the comparative role of laser wavelengths and pulse widths in controlling the nanoparticle sizes, morphology and production rate. In this investigation, Ag, Au and TiO2 nanoparticles were synthesised by nanosecond ( λ = 532 nm, τ = 5 ns), picosecond ( λ = 1064 nm, τ = 10 ps) and femtosecond ( λ = 800 nm, τ = <100 fs) pulse lasers in deionised water. They are compared, in terms of their optical absorption spectra, morphology, size distribution and production rates, characterised by UV-Vis spectroscopy and transmission electron microscopy. The ablation rates of both Ag and Ti samples were shown as a function of laser pulse energy and water level above the samples. The average size of nanoparticles (10-50 nm) was found to be smaller for the shorter wavelength (532 nm) nanosecond pulsed laser compared with those of picosecond and femtosecond lasers, demonstrating a more dominating role of laser wavelength than pulse width in particle size control. The ps laser generated more spherical Ag nanoparticles than those with the ns and fs lasers. Under the same laser processing conditions, Au nanoparticles are smaller than Ag and TiO2, with the latter, the largest. The nanoparticle production rate is relatively independent upon laser types, wavelengths and pulse lengths, but largely determined by the laser fluence and energy deposited.

  7. Conductive and transparent multilayer films for low-temperature TiO2/Ag/SiO2 electrodes by E-beam evaporation with IAD

    PubMed Central

    2014-01-01

    Conductive and transparent multilayer thin films consisting of three alternating layers (TiO2/Ag/SiO2, TAS) have been fabricated for applications as transparent conducting oxides. Metal oxide and metal layers were prepared by electron-beam evaporation with ion-assisted deposition, and the optical and electrical properties of the resulting films as well as their energy bounding characteristics and microstructures were carefully investigated. The optical properties of the obtained TAS material were compared with those of well-known transparent metal oxide glasses such as ZnO/Ag/ZnO, TiO2/Ag/TiO2, ZnO/Cu/ZnO, and ZnO/Al/ZnO. The weathering resistance of the TAS film was improved by using a protective SiO2 film as the uppermost layer. The transmittance spectra and sheet resistance of the material were carefully measured and analyzed as a function of the layer thickness. By properly adjusting the thickness of the metal and dielectric films, a low sheet resistance of 6.5 ohm/sq and a high average transmittance of over 89% in the 400 to 700 nm wavelength regions were achieved. We found that the Ag layer played a significant role in determining the optical and electrical properties of this film. PMID:24433437

  8. TiO2 nanotube composite layers as delivery system for ZnO and Ag nanoparticles - an unexpected overdose effect decreasing their antibacterial efficacy.

    PubMed

    Roguska, A; Belcarz, A; Pisarek, M; Ginalska, G; Lewandowska, M

    2015-06-01

    Enhancement of biocompatibility and antibacterial properties of implant materials is potentially beneficial for their practical value. Therefore, the use of metallic and metallic oxide nanoparticles as antimicrobial coatings components which induce minimized antibacterial resistance receives currently particular attention. In this work, TiO2 nanotubes layers loaded with ZnO and Ag nanoparticles were designed for biomedical coatings and delivery systems and evaluated for antimicrobial activity. TiO2 nanotubes themselves exhibited considerable and diameter-dependent antibacterial activity against planktonic Staphylococcus epidermidis cells but favored bacterial adhesion. Loading of nanotubes with moderate amount of ZnO nanoparticles significantly diminished S. epidermidis cell adhesion and viability just after 1.5h contact with modified surfaces. However, an increase of loaded ZnO amount unexpectedly altered the structure of nanoparticle-nanolayer, caused partial closure of nanotube interior and significantly reduced ZnO solubility and antibacterial efficacy. Co-deposition of Ag nanoparticles enhanced the antibacterial properties of synthesized coatings. However, the increase of ZnO quantity on Ag nanoparticles co-deposited surfaces favored the adhesion of bacterial cells. Thus, ZnO/Ag/TiO2 nanotube composite layers may be promising delivery systems for combating post-operative infections in hard tissue replacement procedures. However, the amount of loaded antibacterial agents must be carefully balanced to avoid the overdose and reduced efficacy. PMID:25842121

  9. Evaluation of bimetal doped TiO2 in dye fragmentation and its comparison to mono-metal doped and bare catalysts

    NASA Astrophysics Data System (ADS)

    Malika, Manjakuppam; Rao, Ch. Venkatanarasimha; Das, Raj Kumar; Giri, Ardhendu Sekhar; Golder, Animes Kumar

    2016-04-01

    There are instances that bimetal doped semiconductor materials impart superior photocatalytic activity than bare and mono-metal doping. In this study, visible light responsive mono- (Cu/TiO2 and Ni/TiO2) and bi-metal doped (Cu-Ni/TiO2) TiO2 photocatalysts with wide band gap energy were synthesized via co-precipitation method with an equal mass ratio of Cu and Ni. The catalyst characterization was performed using Diffuse Reflectance UV-visible (DR-UV-vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), zeta-potential and Transmission Electron Microscopy (TEM) analyzes. The charge balancing effect of Cu and Ni caused a notable reduction in the optical band gap of TiO2 to 2.91 eV with Cu-Ni/TiO2. The synthesis method increased the anatase phase significantly along with the crystallite size. Cu-Ni/TiO2 displayed a lesser destabilization tendency, and the absolute value of zeta-potentials increased much at pH > pHzpc resulted from the higher oxygen vacancies. The activity of Ni/TiO2, Cu/TiO2, and Cu-Ni/TiO2 was tested for the degradation dynamics and kinetics of Eriochrome Cyanine Red (ECR), an anionic dye. Cu doping exhibited a better dye decomposition because of the low recombination rate of electron/hole pair as a full 3d sub-level of Cu is energetically more favorable than a full 4s sub-level of Ni. The mechanism of dye decomposition releasing inorganic ions is also proposed and validated from the mass spectra.

  10. Dopant location identification in Nd3+ doped TiO2 nanoparticles

    SciTech Connect

    Li, W.; Frenkel, A.; Woicik, J.; Ni, C.; Shah, S.

    2010-12-03

    Large band gap semiconductors are typically doped in order to enhance their photocatalytic, photovoltaic, and other chemical and optoelectronic properties. The identification of dopant position and its local environment are essential to explore the effect of doping. X ray techniques, including extended x ray absorption fine structure, x ray photoelectron spectroscopy, and x ray diffraction, were performed to analyze the Nd (0 to 1.5 at. %) dopant location and the structural changes associated with the doping in anatase TiO{sub 2} nanoparticles, which were synthesized by metalorganic chemical vapor deposition. Nd ions were determined to have a trivalent chemical state and substitute for Ti{sup 4+} in the TiO{sub 2} structure. The substitutional Nd{sup 3+} ions cause anatase lattice expansion along c direction with a maximum value of 0.15 {angstrom} at 1.5% Nd doping level and the local structure of the dopants changes towards rutile like configuration. The lengths of the nearest neighbor Nd-O and Nd-Ti bonds increase by 0.5-0.8 {angstrom} compared to their counterparts in the pure TiO{sub 2} host structure. The substitutional nature of Nd{sup 3+} dopants explains why they are efficient not only for charge carrier separation but also for visible light absorption in TiO{sub 2}.

  11. A nanotechnology based new approach for chemotherapy of Cutaneous Leishmaniasis: TIO2@AG nanoparticles - Nigella sativa oil combinations.

    PubMed

    Abamor, Emrah Sefik; Allahverdiyev, Adil M

    2016-07-01

    Since toxicity and resistance are the major drawbacks of current antileishmanial drugs, studies have been recently focused on combination therapy in fight against leishmaniasis. Combination therapy generally provides opportunity to decrease toxicity of applied agents and enhance their antimicrobial performance. Moreover, this method can be effective in preventing drug resistance. Highly antileishmanial effects of silver doped titanium dioxide nanoparticles (TiAgNps) and Nigella sativa oil were demonstrated in previous studies. However, toxicity is still an important factor preventing use of these molecules in clinic. By considering high antileishmanial potential of each agent and basic principles of combination therapy, we propose that use of combinations including non-toxic concentrations of TiAgNps and N. sativa oil may compose more effective and safer formulations against Leishmania parasites. Therefore, the main goal of the present study was to investigate antileishmanial effects of non-toxic concentrations of TiAgNps and Nigella sativa oil combinations on promastigote and amastigote-macrophage culture systems and also to develop nanotechnology based new antileishmanial strategies against Cutaneous Leishmaniasis. Numerous parameters such as proliferation, metabolic activity, apoptosis, amastigote-promastigote conversion, infection index analysis and nitric oxide production were used to detect antileishmanial efficacies of combinations. Investigated all parameters demonstrated that TiAgNps-N. sativa oil combinations had significant antileishmanial effect on each life forms of parasites. Tested combinations were found to decrease proliferation rates of Leishmania tropica promastigotes in a range between 1,5-25 folds and metabolic activity values between 2 and 4 folds indicating that combination applications lead to virtually inhibition of promastigotes and elimination of parasites were directly related to apoptosis manner. TiAgNps-N. sativa combinations also

  12. Improved performance of dye sensitized solar cells using Cu-doped TiO2 as photoanode materials: Band edge movement study by spectroelectrochemistry

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Wei, Liguo; Yang, Yulin; Xia, Xue; Wang, Ping; Yu, Jia; Luan, Tianzhu

    2016-08-01

    Cu-doped TiO2 nanoparticles are prepared and used as semiconductor materials of photoanode to improve the performance of dye sensitized solar cells (DSSCs). UV-Vis spectroscopy and variable temperature spectroelectrochemistry study are used to characterize the influence of copper dopant with different concentrations on the band gap energies of TiO2 nanoparticles. The prepared Cu-doped TiO2 semiconductor has avoided the formation of CuO during hydrothermal process and lowered the conduction band position of TiO2, which contribute to increase the short circuit current density of DSSCs. At the optimum Cu concentration of 1.0 at.%, the short circuit current density increased from 12.54 to 14.98 mA cm-2, full sun solar power conversion efficiencies increased from 5.58% up to 6.71% as compared to the blank DSSC. This showed that the presence of copper in DSSCs leads to improvements of up to 20% in the conversion efficiency of DSSCs.

  13. Enhanced visible-light absorption of mesoporous TiO2 by co-doping with transition-metal/nitrogen ions

    SciTech Connect

    Mathis, John; Bi, Zhonghe; Bridges, Craig A; Kidder, Michelle; Paranthaman, Mariappan Parans

    2013-01-01

    Titanium (IV) oxide, TiO2, has been the object of intense scrutiny for energy applications. TiO2 is inexpensive, non-toxic, and has excellent corrosion resistance when exposed to electrolytes. A major drawback preventing the widespread use TiO2 for photolysis is its relatively large band gap of ~3eV. Only light with wavelengths shorter than 400 nm, which is in the ultraviolet portion of the spectrum, has sufficient energy to be absorbed. Less than 14 percent of the solar irradiation reaching the earth s surface has energy exceeding this band gap. Adding dopants such as transition metals has long been used to reduce the gap and increase photocatalytic activity by accessing the visible part of the solar spectrum. The degree to which the band gap is reduced using transition metals depends in part on the overlap of the d-orbitals of the transition metals with the oxygen p-orbitals. Therefore, doping with anions such as nitrogen to modify the cation-anion orbital overlap is another approach to reduce the gap. Recent studies suggest that using a combination of transition metals and nitrogen as dopants is more effective at introducing intermediate states within the band gap, effectively narrowing it. Here we report the synthesis of mesoporous TiO2 spheres, co-doped with transition metals and nitrogen that exhibit a nearly flat absorbance response across the visible spectrum extending into the near infrared.

  14. Study on the water durability of zinc boro-phosphate glasses doped with MgO, Fe2O3, and TiO2

    NASA Astrophysics Data System (ADS)

    Hwang, Moon Kyung; Ryu, Bong Ki

    2016-07-01

    The water durability of zinc boro-phosphate (PZB) glasses with the composition 60P2O5-20ZnO-20B2O3- xMeO ( x = 0, 2, 4, 6 and MeO = MgO, Fe2O3, or TiO2) (mol%) was measured, and PZB glass was studied in terms of its thermal properties, density, and FTIR characteristics. The surface conditions and corrosion byproducts were analyzed using scanning electron microscopy. When MgO, Fe2O3, and TiO2 were doped into the PZB glass, Q2 was decreased and Q1 was increased in the phosphate structure, while the number of BO4 structures increased with increasing MeO content. The density of the PZB glass was increased by the addition of Fe2O3 and TiO2, while the glass transition temperature ( T g ) and dilatometric softening temperature ( T d ) were increased when additional MgO, Fe2O3, and TiO2 were added. From the weight loss analysis (95 ◦ C, 96 h), TiO2 doped glass showed the lowest weight loss (1.70 × 10 -3 g/cm2) while MgO doped glass showed the highest value (2.44 × 10 -3 g/cm2), compared with PZB glass (3.07 × 10 -3 g/cm2). These results were discussed in terms of the Me n+ ions in the glass structure, and their different coordination numbers and bonding strengths.

  15. Bandgap tailoring of in-situ nitrogen-doped TiO2 sputtered films intended for electrophotocatalytic applications under solar light

    NASA Astrophysics Data System (ADS)

    Delegan, N.; Daghrir, R.; Drogui, P.; El Khakani, M. A.

    2014-10-01

    We report on a reactive RF-sputtering process permitting the in-situ nitrogen doping of TiO2 films in order to shift their photoactivity from UV to visible range. By carefully controlling the relative nitrogen-to-argon mass flow rate ratio (within the 0%-25% range) in the sputter deposition chamber, TiO2:N films were grown with nitrogen contents ranging from 0 to 6.2 at. %, as determined by high-resolution X-ray spectroscopy measurements. A systematic investigation of the crystalline structure of the TiO2:N films, as a function of their N content, revealed that low N contents (0.2-0.3 at. %) induce crystallization in the rutile phase while higher N contents (≥1.4 at. %) were accompanied with the recovery of the anatase structure with an average crystallite size of ˜35 nm. By using both UV-Vis absorption and spectroscopic ellipsometry measurements, we were able to quantitatively determine the bandgap (Eg) variation of the TiO2:N films as a function of their N content. Thus, we have demonstrated that the Eg of the TiO2:N films effectively narrows from 3.2 eV down to a value as low as ˜2.3 eV for the optimal N doping concentration of 3.4 at. % (higher N incorporation does not translate into further red shifting of the TiO2:N films' Eg). The photoactivity of the TiO2:N films under visible light was confirmed through electro-photocatalytic decomposition of chlortetracycline (CTC, an emerging water pollutant) under standard 1.5AM solar radiation. Thus, CTC degradation efficiencies of up to 98% were achieved with 2 hours process cycles under simulated solar light. Moreover, the electro-photocatalytic performance of the TiO2:N films is shown to be directly correlated to their optoelectronic properties (namely their bandgap narrowing).

  16. Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

    NASA Astrophysics Data System (ADS)

    Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

    2016-03-01

    Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work.

  17. Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method.

    PubMed

    Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

    2016-01-01

    Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm(2) at a current density of 3 mA/cm(2) when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm(2), and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

  18. Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

    PubMed Central

    Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

    2016-01-01

    Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

  19. Transparent Conducting Nb-Doped TiO2 Electrodes Activated by Laser Annealing for Inexpensive Flexible Organic Solar Cells

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hsiang; Lin, Chia-Chi; Lin, Yi-Chang

    2012-01-01

    A KrF excimer laser (λ= 248 nm) has been adopted for annealing cost-effective Nb-doped TiO2 (NTO) films. Sputtered NTO layers were annealed on SiO2-coated flexible poly(ethylene terephthalate) (PET) substrates. This local laser annealing technique is very useful for the formation of anatase NTO electrodes used in flexible organic solar cells (OSCs). An amorphous NTO film with a high resistivity and a low transparency was transformed significantly into a conductive and transparent anatase NTO electrode by laser irradiation. The 210 nm anatase NTO film shows a sheet resistance of 50 Ω and an average optical transmittance of 83.5% in the wavelength range from 450 to 600 nm after annealing at 0.25 J/cm2. The activation of Nb dopants and the formation of the anatase phase contribute to the high conductivity of the laser-annealed NTO electrode. Nb activation causes an increase in the optical band gap due to the Burstein-Moss effect. The electrical properties are in agreement with the material characteristics determined by X-ray diffraction (XRD) analysis and secondary ion mass spectrometry (SIMS). The irradiation energy for the NTO electrode also affects the performance of the organic solar cell. The laser annealing technique provides good properties of the anatase NTO film used as a transparent electrode for flexible organic solar cells (OSCs) without damage to the PET substrate or layer delamination from the substrate.

  20. Surface-enhanced Raman scattering (SERS) activity of Ag, Au and Cu nanoclusters on TiO 2-nanotubes/Ti substrate

    NASA Astrophysics Data System (ADS)

    Roguska, Agata; Kudelski, Andrzej; Pisarek, Marcin; Opara, Magdalena; Janik-Czachor, Maria

    2011-07-01

    Tubular arrays of TiO 2 nanotubes (ranging in diameter from 40 to 110 nm) on a Ti substrate were used as a support for Ag, Au or Cu deposits obtained by the sputter deposition technique, where the amount of metal varied from 0.01 to 0.2 mg/cm 2. Those composite supports were intended for surface-enhanced Raman scattering (SERS) investigations. Composite samples were studied with the aid of scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) to reveal their characteristic morphological and chemical features. Raman spectra of pyridine (as a probe molecule) were measured at different cathodic potentials ranging from -0.2 down to -1.2 V after the pyridine had been adsorbed on the metal-covered TiO 2 nanotube/Ti substrates. In addition, SERS spectra on a bulk standard activated Ag, Au and Cu substrates were also measured. The SERS activity of the composite samples was strongly dependent on the amount of metal deposit, e.g. at and above 0.06 mg Ag/cm 2, the intensity of SERS signal was even higher than that for the Ag reference substrate. The high activity of these composites is mainly a result of their specific morphology. The high SERS sensitivity on the surface morphology of the substrate made it possible to monitor very small temporal changes in the Ag metal clusters. This rearrangement was not detectable with microscopic (SEM) or microanalytical (AES) methods. The SERS activity of Au or Cu clusters was distinctly lower than those of Ag. The spectral differences exhibited by the three kinds of composites as compared to the reference metal samples are discussed.

  1. Solution-processed, antimony-doped tin oxide colloid films enable high-performance TiO2 photoanodes for water splitting.

    PubMed

    Peng, Qing; Kalanyan, Berç; Hoertz, Paul G; Miller, Andrew; Kim, Do Han; Hanson, Kenneth; Alibabaei, Leila; Liu, Jie; Meyer, Thomas J; Parsons, Gregory N; Glass, Jeffrey T

    2013-04-10

    Photoelectrochemical (PEC) water splitting and solar fuels hold great promise for harvesting solar energy. TiO2-based photoelectrodes for water splitting have been intensively investigated since 1972. However, solar-to-fuel conversion efficiencies of TiO2 photoelectrodes are still far lower than theoretical values. This is partially due to the dilemma of a short minority carrier diffusion length, and long optical penetration depth, as well as inefficient electron collection. We report here the synthesis of TiO2 PEC electrodes by coating solution-processed antimony-doped tin oxide nanoparticle films (nanoATO) on FTO glass with TiO2 through atomic layer deposition. The conductive, porous nanoATO film-supported TiO2 electrodes, yielded a highest photocurrent density of 0.58 mA/cm(2) under AM 1.5G simulated sunlight of 100 mW/cm(2). This is approximately 3× the maximum photocurrent density of planar TiO2 PEC electrodes on FTO glass. The enhancement is ascribed to the conductive interconnected porous nanoATO film, which decouples the dimensions for light absorption and charge carrier diffusion while maintaining efficient electron collection. Transient photocurrent measurements showed that nanoATO films reduce charge recombination by accelerating transport of photoelectrons through the less defined conductive porous nanoATO network. Owing to the large band gap, scalable solution processed porous nanoATO films are promising as a framework to replace other conductive scaffolds for PEC electrodes. PMID:23537229

  2. Identification of the arsenic resistance on MoO3 doped CeO2/TiO2 catalyst for selective catalytic reduction of NOx with ammonia.

    PubMed

    Li, Xiang; Li, Xiansheng; Li, Junhua; Hao, Jiming

    2016-11-15

    Arsenic resistance on MoO3 doped CeO2/TiO2 catalysts for selective catalytic reduction of NOx with NH3 (NH3-SCR) is investigated. It is found that the activity loss of CeO2-MoO3/TiO2 caused by As oxide is obvious less than that of CeO2/TiO2 catalysts. The fresh and poisoned catalysts are compared and analyzed using XRD, Raman, XPS, H2-TPR and in situ DRIFTS. The results manifest that the introduction of arsenic oxide to CeO2/TiO2 catalyst not only weakens BET surface area, surface acid sites and adsorbed NOx species, but also destroy the redox circle of Ce(4+) to Ce(3+) because of interaction between Ce and As. When MoO3 is added into CeO2/TiO2 system, the main SCR reaction path are found to be changed from the reaction between coordinated NH3 and ad-NOx species to that between an amide and gaseous NO. Additionally, for CeO2-MoO3/TiO2 catalyst, As toxic effect on active sites CeO2 can be released because of stronger As-Mo interaction. Moreover, not only are the reactable Brønsted and Lewis acid sites partly restored, but the cycle of Ce(4+) to Ce(3+) can also be free to some extent. PMID:27474851

  3. Magnetically separable Fe3O4@SiO2@TiO2-Ag microspheres with well-designed nanostructure and enhanced photocatalytic activity.

    PubMed

    Chi, Yue; Yuan, Qing; Li, Yanjuan; Zhao, Liang; Li, Nan; Li, Xiaotian; Yan, Wenfu

    2013-11-15

    Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical-chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron-hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application. PMID:24076477

  4. Effect of TiO2 nanoparticle doping on the performance of electrically-controlled nematic liquid crystal core waveguide switch

    NASA Astrophysics Data System (ADS)

    Sharma, Mukesh; Sinha, Aloka; Shenoy, M. R.

    2015-11-01

    A liquid crystal (LC) core waveguide has been designed and fabricated using nanocolloid of the nematic liquid crystal 5CB, doped with TiO2 nanoparticles, as the core. Nematic liquid crystals doped with small amount of nanoparticles can have significantly altered electro-optic response. The performance of the fabricated LC core waveguide as an optical-switch has been studied, and the experimental result shows that the threshold voltage for switching is reduced from 1 V to 0.25 V due to TiO2 nanoparticle dopant-concentration of 2.0 wt.%. The overall optimal performance of the waveguide switch, in terms of threshold voltage, extinction ratio, and response time, is achieved for a dopant-concentration of 0.5 wt.%.

  5. Effective role of trifluoroacetic acid (TFA) to enhance the photocatalytic activity of F-doped TiO2 prepared by modified sol-gel method

    NASA Astrophysics Data System (ADS)

    Samsudin, Emy Marlina; Hamid, Sharifah Bee Abd; Juan, Joon Ching; Basirun, Wan Jefrey; Kandjani, Ahmad Esmaielzadeh; Bhargava, Suresh K.

    2016-03-01

    Highly photoactive mesoporous F-doped TiO2 with improved physico-chemical characteristics is achieved using modified sol-gel method. The usage of trifluoroacetic as fluorine precursor significantly modifies the morphology, size, pore shape, crystal phase, crystal structure, surface chemical state and to a lesser extent, {1 0 1} and {0 0 1} facets. The accessibility of fluoride ions on Tisbnd Osbnd Ti polymer chains during crystal growth during the sol-gel process remarkably influences the properties of catalyst. To the best of our knowledge, preparation of F-doped TiO2 using modified sol-gel and trifluoroacetic acid are limited, and still not enough. Thus this work provides additional insight by using an approach which is less hazardous, less costly and practical for large scale agile development in the photocatalysis industry.

  6. Ga-doped ZnO transparent electrodes with TiO2 blocking layer/nanoparticles for dye-sensitized solar cells

    PubMed Central

    2012-01-01

    Ga-doped ZnO [GZO] thin films were employed for the transparent electrodes in dye-sensitized solar cells [DSSCs]. The electrical property of the deposited GZO films was as good as that of commercially used fluorine-doped tin oxide [FTO]. In order to protect the GZO and enhance the photovoltaic properties, a TiO2 blocking layer was deposited on the GZO surface. Then, TiO2 nanoparticles were coated on the blocking layer, and dye was attached for the fabrication of DSSCs. The fabricated DSSCs with the GZO/TiO2 glasses showed an enhanced conversion efficiency of 4.02% compared to the devices with the normal GZO glasses (3.36%). Furthermore, they showed better characteristics even than those using the FTO glasses, which can be attributed to the reduced charge recombination and series resistance. PMID:22222148

  7. Numerical study of the structural and vibrational properties of amorphous Ta2O5 and TiO2-doped Ta2O5

    NASA Astrophysics Data System (ADS)

    Damart, T.; Coillet, E.; Tanguy, A.; Rodney, D.

    2016-05-01

    Using classical molecular dynamics simulations, we synthesized amorphous Ta2O5 and amorphous TiO2-doped Ta2O5. We show that Ta2O5 is composed primarily of six-folded Ta atoms forming octahedra that are either organized in chain-like structures or share edges or faces. When Ta2O5 is doped with TiO2, Ti atoms form equally five- and six-folded polyhedra that perturb but do not break the network structure of the glass. Performing a vibrational eigenmode analysis and projecting the eigenmodes on the rocking, stretching, and bending motions of the Ta-2O and Ta-3O bonds, we provide an atomic-scale analysis that substantiates the interpretations of Raman spectra of amorphous Ta2O5. This eigenmode analysis also reveals the key role played by Ti atoms in the 5 to 12 THz range.

  8. A new preparation of doped photocatalytic TiO2 anatase nanoparticles: a preliminary study for the removal of pollutants in confined museum areas

    NASA Astrophysics Data System (ADS)

    Greco, Enrico; Ciliberto, Enrico; Cirino, Antonio M. E.; Capitani, Donatella; Di Tullio, Valeria

    2016-05-01

    The use of nanotechnology in conservation is a relatively new concept. Usually, classical cleanup methods take into account the use of other chemicals: On the one hand they help the environment destroying pollutants, but on the other hand they often become new pollutants. Among the new oxidation methods called advanced oxidation processes, heterogeneous photocatalysis has appeared an emerging technology with several economic and environmental advantages. A new sol-gel method of synthesis of TiO2 anatase is reported in this work using lithium and cobalt (II) salts. The activation energy of the doped photocatalyst was analyzed by solid-state UV-Vis spectrophotometer. The mobility of Li ions on TiO2 NPs surface was studied by 7Li MAS NMR spectroscopy. Use of doped nanotitania is suggested from authors for the removal of pollutants in confined areas containing goods that must be preserved from decomposition and aging phenomena.

  9. UV-vis light activated Ag decorated monodisperse TiO2 for treatment of pharmaceuticals in water

    EPA Science Inventory

    Recently, many researchers have made a lot of effort to utilize the visible light portion of the solar spectrum to activate TiO2 photocatalyst for environmental applications, such as water, air, and soil remediation. The deposition of noble metals on photocatalysts is of great in...

  10. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO2

    NASA Astrophysics Data System (ADS)

    Galenda, A.; Crociani, L.; Habra, N. El; Favaro, M.; Natile, M. M.; Rossetto, G.

    2014-09-01

    Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV-vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.

  11. Carbon-Dot-Sensitized, Nitrogen-Doped TiO2 in Mesoporous Silica for Water Decontamination through Nonhydrophobic Enrichment-Degradation Mode.

    PubMed

    Cheng, Chen; Tan, Xianjun; Lu, Deli; Wang, Lingzhi; Sen, Tapas; Lei, Juying; El-Toni, Ahmed Mohamed; Zhang, Jinlong; Zhang, Fan; Zhao, Dongyuan

    2015-12-01

    Mesoporous silica synthesized from the cocondensation of tetraethoxysilane and silylated carbon dots containing an amide group has been adopted as the carrier for the in situ growth of TiO2 through an impregnation-hydrothermal crystallization process. Benefitting from initial complexation between the titania precursor and carbon dot, highly dispersed anatase TiO2 nanoparticles can be formed inside the mesoporous channel. The hybrid material possesses an ordered hexagonal mesostructure with p6mm symmetry, a high specific surface area (446.27 m(2)  g(-1) ), large pore volume (0.57 cm(3)  g(-1) ), uniform pore size (5.11 nm), and a wide absorption band between λ=300 and 550 nm. TiO2 nanocrystals are anchored to the carbon dot through TiON and TiOC bonds, as revealed by X-ray photoelectron spectroscopy. Moreover, the nitrogen doping of TiO2 is also verified by the formation of the TiN bond. This composite shows excellent adsorption capabilities for 2,4-dichlorophenol and acid orange 7, with an electron-deficient aromatic ring, through electron donor-acceptor interactions between the carbon dot and organic compounds instead of the hydrophobic effect, as analyzed by the contact angle analysis. The composite can be photocatalytically recycled through visible-light irradiation after adsorption. The narrowed band gap, as a result of nitrogen doping, and the photosensitization effect of carbon dots are revealed to be coresponsible for the visible-light activity of TiO2 . The adsorption capacity does not suffer any clear losses after being recycled three times. PMID:26487497

  12. Enhancing the photocatalytic activity of TiO2 co-doping of graphene-Fe3+ ions for formaldehyde removal.

    PubMed

    Low, Wasu; Boonamnuayvitaya, Virote

    2013-09-30

    In the present work, graphene and Fe(3+) ions were doped to enhance the photocatalytic activity of a TiO2 photocatalyst with the expectation of synergistic effects on the specific surface area and electronic conductivity due to the formation of Ti-O-C bonds preventing charge recombination contributed by graphene and band gap energy narrowing by doping with Fe(3+) ions. GR/Fe(3+)-TiO2 was successfully synthesized by the refluxed peroxo titanic acid (PTA) method and was tested for gaseous formaldehyde removal. The results show that graphene contributed to formaldehyde adsorption since the equilibrium adsorption capacity increased with an increasing weight ratio of graphene. The GR/Fe(3+)-TiO2 photocatalyst with a weight ratio of graphene to TiO2 (PTA) of 1:50 and the Fe(3+) dopant at 0.12 wt% was optimal. An equilibrium formaldehyde adsorption capacity of 10.2 mg(HCHO) g(-1)catalyst and photodegradation efficiency of about 50.3% and 25.5% under UV and visible light irradiation for 90 min, respectively, were obtained. It was observed that the adsorption property of the catalyst was increased by adding graphene and the extendable absorption edge of light to longer wavelengths was attributed to the synergistic effect of graphene and Fe(3+) dopants on the band gap energy of the catalyst. The greater photocatalytic activity of GR/Fe(3+)-TiO2 compared to GR-TiO2 resulted from more hydroxyl (OH) and superoxide [Formula: see text] radicals produced via redox reactions with Fe ions. PMID:23694821

  13. The effect of frit glass content on the crystalline structure, microstructure and electrical properties of local mineral and Fe2O3 doped TiO2 films

    NASA Astrophysics Data System (ADS)

    Denny, Yus Rama; Syarif, Dani Gustaman; Ruhiat, Yayat; Firmansyah, Teguh; Suherman, Andri

    2016-02-01

    The electrical, crystal structure and microstructure properties of NTC thermistor from local mineral (containing Fe2O3-SiO2-K2O-Na2O-MnO) doped TiO2 thick films were investigated by means of electrical measurement, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD revealed that the crystalline of all thick film has a hexagonal (illminite) structure without changing in different frit glass content. The microstructure of thick films was discussed by utilizing SEM analysis. The results showed that the film with lower frit glass content has a lower electrical resistivity and thermistor parameter. This result demonstrated that the electrical properties of the thick films can be improved by changing the frit glass content. In addition, the comparison of FeTiO3 thick films from local mineral doped TiO2 with the pure Fe2O3 doped TiO2 (Fe2O3 powder having the purity of 99.9%) were discussed. We believe that our results can be a good guide for those fabricating FeTiO3 thick films with the purpose of device applications, which require thermistor with high β and low resistivity.

  14. Exchange mechanism of half-metallic ferromagnetism of TiO 2 doped with double impurities: A first-principles ASW study

    NASA Astrophysics Data System (ADS)

    Fakhim Lamrani, A.; Belaiche, M.; Benyoussef, A.; El Kenz, A.; Saidi, E. H.

    2010-02-01

    The electronic structure and ferromagnetic properties of rutile TiO 2 doped with double-impurities Ti 1-2xCr xMn xO 2 has been investigated using first-principles calculations within the density-functional theory (DFT) and the local density approximation (LDA), functional for treating the effects of exchange and correlation. They were performed using the scalar-relativistic implementation of the augmented spherical wave (ASW). The advantages of doping TiO 2 with double impurities instead of single impurities are the increase of the total moment of the system and the exhibition of the half-metallic ferromagnetic nature in Cr- and Mn-doped TiO 2 rutile. These behaviors are due to the hybridization of Cr 3d states and nearest-neighboring O 2p states. The spin-spin interaction between magnetic impurities examined by the total energy between parallel and antiparallel aligned states indicated that the Cr and Mn impurities are energetically favorable to be parallel coupled, which mean that the ferromagnetic state is more stable than the ferrimagnetic one. We proposed a bond magnetic polarons (BMP) model, based on localized carriers, to explain the mechanism of ferromagnetism in these systems.

  15. LED and low level laser therapy association in tooth bleaching using a novel low concentration H2O2/N-doped TiO2 bleaching agent

    NASA Astrophysics Data System (ADS)

    Bezerra Dias, Hércules; Teixeira Carrera, Emanuelle; Freitas Bortolatto, Janaína; Ferrarezi de Andrade, Marcelo; Nara de Souza Rastelli, Alessandra

    2016-01-01

    Since low concentration bleaching agents containing N-doped TiO2 nanoparticles have been introduced as an alternative to conventional agents, it is important to verify their efficacy and the hypersensitivity effect in clinical practice. Six volunteer patients were evaluated for color change and hypersensitivity after bleaching using 35% H2O2 (one session of two 12 min applications) and 6% H2O2/N-doped TiO2 (one session of three 12 min applications) and after low level laser therapy application (LLLT) (780 nm, 40 mW, 10 J.cm-2, 10 s). Based on this case study, the nanobleaching agent provided better or similar aesthetic results than the conventional agent under high concentration, and its association with LLLT satisfactorily decreased the hypersensitivity. The 6% H2O2/N-doped TiO2 agent could be used instead of conventional in-office bleaching agents under high concentrations to fulfill the rising patient demand for aesthetics.

  16. Compositing amorphous TiO2 with N-doped carbon as high-rate anode materials for lithium-ion batteries.

    PubMed

    Xiao, Ying; Hu, Changwen; Cao, Minhua

    2014-01-01

    Compositing amorphous TiO2 with nitrogen-doped carbon through Ti-N bonding to form an amorphous TiO2/N-doped carbon hybrid (denoted a-TiO2/C-N) has been achieved by a two-step hydrothermal-calcining method with hydrazine hydrate as an inhibitor and nitrogen source. The resultant a-TiO2/C-N hybrid has a surface area as high as 108 m(2) g(-1) and, when used as an anode material, exhibits a capacity as high as 290.0 mA h g(-1) at a current rate of 1 C and a reversible capacity over 156 mA h g(-1) at a current rate of 10 C after 100 cycles; these results are better than those found in most reports on crystalline TiO2 . This superior electrochemical performance could be ascribed to a combined effect of several factors, including the amorphous nature, porous structure, high surface area, and N-doped carbon. PMID:24347075

  17. Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics

    PubMed Central

    Li, Jinglei; Li, Fei; Li, Chao; Yang, Guang; Xu, Zhuo; Zhang, Shujun

    2015-01-01

    The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference in grain size. The dielectric and I–V behaviors of SPS and CSSS samples were investigated. Though both possess colossal permittivity (CP), the SPS samples exhibited much higher dielectric permittivity/loss factor and lower breakdown electric field when compared to their CSSS counterparts. To further explore the origin of CP in co-doped TiO2 ceramics, the I–V behavior was studied on single grain and grain boundary in CSSS sample. The nearly ohmic I–V behavior was observed in single grain, while GBs showed nonlinear behavior and much higher resistance. The higher dielectric permittivity and lower breakdown electric field in SPS samples, thus, were thought to be associated with the feature of SPS, by which reduced space charges and/or impurity segregation can be achieved at grain boundaries. The present results support that the grain boundary capacitance effect plays an important role in the CP and nonlinear I–V behavior of (Nb + In) co-doped TiO2 ceramics. PMID:25656713

  18. Rapid flame synthesis of internal Mo(6+) doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters for lithium ion storage.

    PubMed

    Li, Yunfeng; Hu, Yanjie; Shen, Jianhua; Jiang, Haibo; Min, Guoquan; Qiu, Shengjie; Song, Zhitang; Sun, Zhuo; Li, Chunzhong

    2015-11-28

    The rational design of nanoheterostructured materials has attracted much attention because of its importance for developing highly efficient LIBs. Herein, we have demonstrated that internal Mo(6+) doped TiO2 nanocrystals in situ decorated with highly dispersed MoO3 clusters have been realized by a facile and rapid flame spray pyrolysis route for electrochemical energy storage. In such intriguing nanostructures, internal Mo(6+) doping can improve the conductivity of electrode materials and facilitate rapid Li(+) intercalation and ion transport and the heteroassembly of highly dispersed ultrafine MoO3 clusters with excellent electrochemical activity endows the TiO2 with extra Li(+) ion storage ability as well as incorporates Mo(6+). Thus, the as-prepared nanohybrid electrodes exhibit a high specific capacity and superior rate capability due to the maximum synergetic effect of TiO2, Mo(6+) and ultrafine MoO3 clusters. Moreover, the aerosol flame process with a unique temperature gradient opens a new strategy to design novel hybrid materials by the simultaneous doping and heteroassembly engineering for next-generation LIBs. PMID:26490363

  19. Tm-doped TiO2 and Tm2Ti2O7 pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

    PubMed Central

    De los Santos, Desiré M; Aguilar, Teresa; Sánchez-Coronilla, Antonio; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Piñero, Jose Carlos; Blanco, Ginesa; Martín-Calleja, Joaquín

    2015-01-01

    Summary Tm-doped TiO2 nanoparticles were synthesized using a water-controlled hydrolysis reaction. Analysis was performed in order to determine the influence of the dopant concentration and annealing temperature on the phase, crystallinity, and electronic and optical properties of the resulting material. Various characterization techniques were utilized such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm3+. ICP–AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm3+ was confirmed by X-ray photoelectron spectroscopy and UV–vis spectroscopy: the incorporation of Tm3+ was confirmed by the generation of new absorption bands that could be assigned to Tm3+ transitions. Furthermore, when the samples were annealed at 1173 K, a pyrochlore phase (Tm2Ti2O7) mixed with TiO2 was obtained with a predominant rutile phase. The photodegradation of methylene blue showed that this pyrochlore phase enhanced the photocatalytic activity of the rutile phase. PMID:25821701

  20. Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics

    NASA Astrophysics Data System (ADS)

    Li, Jinglei; Li, Fei; Li, Chao; Yang, Guang; Xu, Zhuo; Zhang, Shujun

    2015-02-01

    The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference in grain size. The dielectric and I-V behaviors of SPS and CSSS samples were investigated. Though both possess colossal permittivity (CP), the SPS samples exhibited much higher dielectric permittivity/loss factor and lower breakdown electric field when compared to their CSSS counterparts. To further explore the origin of CP in co-doped TiO2 ceramics, the I-V behavior was studied on single grain and grain boundary in CSSS sample. The nearly ohmic I-V behavior was observed in single grain, while GBs showed nonlinear behavior and much higher resistance. The higher dielectric permittivity and lower breakdown electric field in SPS samples, thus, were thought to be associated with the feature of SPS, by which reduced space charges and/or impurity segregation can be achieved at grain boundaries. The present results support that the grain boundary capacitance effect plays an important role in the CP and nonlinear I-V behavior of (Nb + In) co-doped TiO2 ceramics.

  1. Evidences of grain boundary capacitance effect on the colossal dielectric permittivity in (Nb + In) co-doped TiO2 ceramics.

    PubMed

    Li, Jinglei; Li, Fei; Li, Chao; Yang, Guang; Xu, Zhuo; Zhang, Shujun

    2015-01-01

    The (Nb + In) co-doped TiO2 ceramics were synthesized by conventional solid-state sintering (CSSS) and spark plasma sintering (SPS) methods. The phases and microstructures were studied by X-ray diffraction, Raman spectra, field-emission scanning electron microscopy and transmission electron microscopy, indicating that both samples were in pure rutile phase while showing significant difference in grain size. The dielectric and I-V behaviors of SPS and CSSS samples were investigated. Though both possess colossal permittivity (CP), the SPS samples exhibited much higher dielectric permittivity/loss factor and lower breakdown electric field when compared to their CSSS counterparts. To further explore the origin of CP in co-doped TiO2 ceramics, the I-V behavior was studied on single grain and grain boundary in CSSS sample. The nearly ohmic I-V behavior was observed in single grain, while GBs showed nonlinear behavior and much higher resistance. The higher dielectric permittivity and lower breakdown electric field in SPS samples, thus, were thought to be associated with the feature of SPS, by which reduced space charges and/or impurity segregation can be achieved at grain boundaries. The present results support that the grain boundary capacitance effect plays an important role in the CP and nonlinear I-V behavior of (Nb + In) co-doped TiO2 ceramics. PMID:25656713

  2. Synthesis, Characterization, and Tribological Evaluation of TiO2-Reinforced Boron and Nitrogen co-Doped Reduced Graphene Oxide Based Hybrid Nanomaterials as Efficient Antiwear Lubricant Additives.

    PubMed

    Jaiswal, Vinay; Kalyani; Umrao, Sima; Rastogi, Rashmi B; Kumar, Rajesh; Srivastava, Anchal

    2016-05-11

    The microwave-synthesized reduced graphene oxide (MRG), boron-doped reduced graphene oxide (B-MRG), nitrogen-doped reduced graphene oxide (N-MRG), boron-nitrogen-co-doped reduced graphene oxide (B-N-MRG), and TiO2-reinforced B-N-MRG (TiO2-B-N-MRG) nanomaterials have been synthesized and characterized by various state-of-the-art techniques, like Raman spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Furthermore, the tribological properties of prepared nanomaterials as antiwear additives in neutral paraffin oil have been evaluated using a four-ball machine at an optimized additive concentration (0.15% w/v). The tribological parameters, like mean wear scar diameter, coefficient of friction, and wear rates, revealed that these nanomaterials have potential to be developed as environmentally friendly sulfated-ash-, phosphorus-, and sulfur-free antiwear lubricant additives. The friction- and wear-reducing behavior of MRG increased upon successive doping of nitrogen, boron, and both nitrogen and boron. Among these additives, B-N-co-doped MRG shows superior tribological behavior in paraffin base oil. Besides this, the load-carrying properties of B-N-co-doped MRG have significantly improved after its reinforcement with TiO2 nanoparticles. A comparative study of the surface morphology of a lubricated track in the presence of various additives has been assessed by SEM and contact-mode atomic force microscopy. The X-ray photoelectron spectroscopy studies have proved that the excellent lubrication properties of TiO2-B-N-MRG are due to the in situ formation of a tribofilm composed of boron nitride, adsorbed graphene layers, and tribosintered TiO2 nanoparticles during the tribocontact. Being sulfur-, halogen-, and phosphorus-free, these graphene-based nanomaterials act as green antiwear additives, protecting interacting

  3. The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO2 : Single-Crystalline Ordered Mesoporous Nb-TiO2 and Plate-like Nb-TiO2 with Ordered Mesoscale Dimples.

    PubMed

    Kitahara, Masaki; Shimasaki, Yuta; Matsuno, Takamichi; Kuroda, Yoshiyuki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2015-09-01

    Highly ordered mesoporous niobium-doped TiO2 with a single-crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb-doped TiO2 . The XPS measurements of Nb-doped TiO2 showed the presence of Nb(5+) and correspondingly Ti(3+) . With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate-like TiO2 with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals. PMID:26216465

  4. Tailoring the electronic and optical properties of anatase TiO2 by (S, Nb) co-doping from a DFT plus U calculation

    NASA Astrophysics Data System (ADS)

    Ren, Dahua; Li, Huiran; Cheng, Xinlu

    2015-12-01

    The geometrical structure, defect formation, electronic and optical properties of S-doped, Nb-doped, and (S, Nb)-codoped anatase TiO2 were successfully calculated by the first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory with plus U method. Firstly, the geometrical structure demonstrates that the (S, Nb) co-doping can effectively induce lattice distortion and reduce the recombination of electron-hole pairs. Note that the (S, Nb)-codoped system further reduces the band gap compared with pure and mono-doped TiO2 due to the mixture of S 2p and Nb 4d states appears in the gap, which results in an obvious red-shift in the optical absorption spectra and improves the photocatalytic activity. Moreover, the (S, Nb) co-doping should be grown under Ti-rich conditions while S or Nb mono-doping is expected to be easier under O-rich conditions. The above results would be beneficial to further developing for titanium dioxide photocatalyst.

  5. Study on the visible-light-induced photokilling effect of nitrogen-doped TiO2 nanoparticles on cancer cells.

    PubMed

    Li, Zheng; Mi, Lan; Wang, Pei-Nan; Chen, Ji-Yao

    2011-01-01

    Nitrogen-doped TiO2 (N-TiO2) nanoparticles were prepared by calcining the anatase TiO2 nanoparticles under ammonia atmosphere. The N-TiO2 showed higher absorbance in the visible region than the pure TiO2. The cytotoxicity and visible-light-induced phototoxicity of the pure- and N-TiO2 were examined for three types of cancer cell lines. No significant cytotoxicity was detected. However, the visible-light-induced photokilling effects on cells were observed. The survival fraction of the cells decreased with the increased incubation concentration of the nanoparticles. The cancer cells incubated with N-TiO2 were killed more effectively than that with the pure TiO2. The reactive oxygen species was found to play an important role on the photokilling effect for cells. Furthermore, the intracellular distributions of N-TiO2 nanoparticles were examined by laser scanning confocal microscopy. The co-localization of N-TiO2 nanoparticles with nuclei or Golgi complexes was observed. The aberrant nuclear morphologies such as micronuclei were detected after the N-TiO2-treated cells were irradiated by the visible light. PMID:21711880

  6. Cobalt-Doped Anatase TiO2: A Room Temperature Dilute Magnetic Dielectric Material

    SciTech Connect

    Griffin, Kelli A.; Pakhomov, Alexandre; Wang, Chong M.; Heald, Steve M.; Krishnan, Kannan M.

    2005-05-15

    Structural and magnetic properties of epitaxial CoxTi₁-xO₂ films with x~2%, grown by RF magnetron sputtering from composite oxide targets on lattice matched LaAIO₃(001) substrates have been investigated. The films were sputtered at a deposition rate of ~0.12 Å/s for a range of substrate temperatures from 300°C to 750°C, followed by UHV annealing for 1 hr at 400°C and aging in air for 3 months. XRD experiments determine the best quality of highly oriented anatase (991) phase in films deposited 500-750°C. Magnetic hysteresis loops at 5K and 300K and thermoremanence measurements from 5-365 K show ferromagnetism in all samples in the whole temperature range. Annealing and aging lead to an increase of spontaneous moment an order of magnitude of up to ~1.1 µB/ Co atom at 300 K. As=deposited, annealed, and aged films were found to be highly resistive changes both in surface morphology and distribution of spontaneous magnetization in the annealed films. Possible mechanisms of the ferromagnetic behavior of such dielectric transition metal-doped oxides will be discussed.

  7. Room temperature magnetization in Co-doped anatase phase of TiO2

    NASA Astrophysics Data System (ADS)

    Karimipour, Masoud; Mageto, Maxwel Joel; Etefagh, Reyhaneh; Azhir, Elahe; Mwamburi, Mghendi; Topalian, Zareh

    2013-01-01

    CoxTi1-xO2 films were deposited by spray pyrolysis technique on Si(1 0 0) substrates at 475 °C. A hydro-alcoholic solution containing titanium (iv) isopropoxide and Co(NO3)2 with various Co doping levels from x = 0-0.015 in solution was used as spray solution. Grazing incident angle of X-ray diffraction illustrates that the CoxTi1-xO2 films are single phase and polycrystal with mixed orientations. Study of surface morphology of the films by atomic force microscope reveals that the annealing atmosphere does not significantly affect the grain size and the microstructure of the films. This study provides further insight into the importance of annealing atmosphere on magnetization of the films. Room temperature magneto-optical Kerr measurement was employed in polar mode. A hysteresis loop and a paramagnetic behavior have been recorded for samples annealed in H2 ambient gas and air, respectively. Chemical composition analysis by X-ray photo-electron spectroscopy showed that Co atoms are bounded to oxygen and no metallic clusters are present. Moreover, it indicates the formation of high spin Co2+ for the sample x = 0.008 annealed in H2 ambient gas. The origin of magnetization can be attributed to the contribution of oxygen vacancies in the spin polarization of the structure.

  8. Highly efficient and recyclable triple-shelled Ag@Fe3O4@SiO2@TiO2 photocatalysts for degradation of organic pollutants and reduction of hexavalent chromium ions

    NASA Astrophysics Data System (ADS)

    Su, Jianwei; Zhang, Yunxia; Xu, Sichao; Wang, Shuan; Ding, Hualin; Pan, Shusheng; Wang, Guozhong; Li, Guanghai; Zhao, Huijun

    2014-04-01

    Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues.Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2

  9. Direct Synthesis of Carbon-Doped TiO2-Bronze Nanowires as Anode Materials for High Performance Lithium-Ion Batteries.

    PubMed

    Goriparti, Subrahmanyam; Miele, Ermanno; Prato, Mirko; Scarpellini, Alice; Marras, Sergio; Monaco, Simone; Toma, Andrea; Messina, Gabriele C; Alabastri, Alessandro; De Angelis, Francesco; Manna, Liberato; Capiglia, Claudio; Zaccaria, Remo Proietti

    2015-11-18

    Carbon-doped TiO2-bronze nanowires were synthesized via a facile doping mechanism and were exploited as active material for Li-ion batteries. We demonstrate that both the wire geometry and the presence of carbon doping contribute to the high electrochemical performance of these materials. Direct carbon doping for example reduces the Li-ion diffusion length and improves the electrical conductivity of the wires, as demonstrated by cycling experiments, which evidenced remarkably higher capacities and superior rate capability over the undoped nanowires. The as-prepared carbon-doped nanowires, evaluated in lithium half-cells, exhibited lithium storage capacity of ∼306 mA h g(-1) (91% of the theoretical capacity) at the current rate of 0.1C as well as excellent discharge capacity of ∼160 mAh g(-1) even at the current rate of 10 C after 1000 charge/discharge cycles. PMID:26492841

  10. Mesoporous nitrogen-doped TiO2 for the photocatalytic destruction of the cyanobacterial toxin microcystin-LR under visible light irradiation.

    PubMed

    Choi, Hyeok; Antoniou, Maria G; Pelaez, Miguel; De la Cruz, Armah A; Shoemaker, Jody A; Dionysiou, Dionysios D

    2007-11-01

    The presence of the harmful cyanobacterial toxins in water resources worldwide drives the development of an innovative and practical water treatment technology with great urgency. This study deals with two important aspects: the fabrication of mesoporous nitrogen-doped TiO2 (N-TiO2) photocatalysts and their environmental application for the destruction of microcystin-LR (MC-LR) under visible light. In a nanotechnological sol-gel synthesis method, a nitrogen-containing surfactant (dodecylammonium chloride) was introduced as a pore templating material for tailor-designing the structural properties of TiO2 and as a nitrogen dopant for its visible light response. The resulting N-TiO2 exhibited significantly enhanced structural properties including 2-8 nm mesoporous structure (porosity 44%) and high surface area of 150 m2/g. Red shift in light absorbance up to 468 nm, 0.9 eV lower binding energy of electrons in Ti 2p state, and reduced interplanar distance of crystal lattices proved nitrogen doping in the TiO2 lattice. Due to its narrow band gap at 2.65 eV, N-TiO2 efficiently degraded MC-LR under visible spectrum above 420 nm. Acidic condition (pH 3.5) was more favorable for the adsorption and photocatalytic degradation of MC-LR on N-TiO2 due to electrostatic attraction forces between negatively charged MC-LR and +6.5 mV charged N-TiO2. Even under UV light, MC-LR was decomposed 3-4 times faster using N-TiO2 than control TiO2. The degradation pathways and reaction intermediates of MC-LR were not directly related to the energy source for TiO2 activation (UV and visible) and nature of TiO2 (neat and nitrogen-doped). This study implies a strong possibility for the in situ photocatalytic remediation of contaminated water with cyanobacterial toxins and other toxic compounds using solar light, a sustainable source of energy. PMID:18044537

  11. Dynamic Mechanisms of the Bactericidal Action of an Al2O3-TiO2-Ag Granular Material on an Escherichia coli Strain

    PubMed Central

    Tartanson, Marie-Anne; Rivallin, Matthieu; Pecastaings, Sophie; Chis, Cristian V.; Penaranda, Diego; Roques, Christine; Faur, Catherine

    2015-01-01

    The bactericidal activity of an Al2O3-TiO2-Ag granular material against an Escherichia coli strain was confirmed by a culture-based method. In particular, 100% of microorganisms were permanently inactivated in 30 to 45 min. The present work aimed to investigate the mechanisms of the bactericidal action of this material and their dynamics on Escherichia coli using different techniques. Observations by transmission electron microscopy (TEM) at different times of disinfection revealed morphological changes in the bacteria as soon as they were put in contact with the material. Notably highlighted were cell membrane damage; cytoplasm detachment; formation of vacuoles, possibly due to DNA condensation, in association with regions exhibiting different levels of electron density; and membrane lysis. PCR and flow cytometry analyses were used to confirm and quantify the observations of cell integrity. The direct exposure of cells to silver, combined with the oxidative stress induced by the reactive oxygen species (ROS) generated, was identified to be responsible for these morphological alterations. From the first 5 min of treatment with the Al2O3-TiO2-Ag material, 98% of E. coli isolates were lysed. From 30 min, cell viability decreased to reach total inactivation, although approximately 1% of permeable E. coli cells and 1% of intact cells (105 genomic units · ml−1) were evidenced. This study demonstrates that the bactericidal effect of the material results from a synergic action of desorbed and supported silver. Supported silver was shown to generate the ROS evidenced. PMID:26253665

  12. Adhesion and inactivation of Gram-negative and Gram-positive bacteria on photoreactive TiO2/polymer and Ag-TiO2/polymer nanohybrid films

    NASA Astrophysics Data System (ADS)

    Tallósy, Szabolcs Péter; Janovák, László; Nagy, Elisabeth; Deák, Ágota; Juhász, Ádám; Csapó, Edit; Buzás, Norbert; Dékány, Imre

    2016-05-01

    The aim of this study was to develop photoreactive surface coatings, possessing antibacterial properties and can be activated under visible light illumination (λmax = 405 nm) using LED-light source. The photocatalytically active titanium dioxide (TiO2) was functionalized with silver nanoparticles (Ag NPs) and immobilized in polyacrylate based nanohybrid thin film in order to facilitate visible light activity (λAg/TiO2,max = 500 nm). First, the photocatalytic activity was modelled by following ethanol vapor degradation. The plasmonic functionalization resulted in 15% enhancement of the activity compared to pure TiO2. The photoreactive antimicrobial (5 log reduction of cfu in 2 h) surface coatings are able to inactivate clinically relevant pathogen strains (methicillin resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa) within short time (60-120 min) due to the formed and quantified reactive oxygen species (ROS). The existence of electrostatic interactions between the negatively charged bacteria (from -0.89 to -3.19 μeq/109 cfu) and positively charged photocatalyst particles (in the range of +0.38 and +12.3 meq/100 g) was also proven by charge titration measurements. The surface inactivation of the bacteria and the photocatalytic degradation of the cell wall component were also confirmed by fluorescence and transmission electron microscopic observations, respectively. According to the results an effective sterilizing system and prevention strategy can be developed and carried out against dangerous microorganisms in health care.

  13. Enhancing carrier generation in TiO2 by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interference.

    PubMed

    Cacciato, Giuseppe; Bayle, Maxime; Pugliara, Alessandro; Bonafos, Caroline; Zimbone, Massimo; Privitera, Vittorio; Grimaldi, Maria Grazia; Carles, Robert

    2015-08-28

    Silver nanoparticles have been embedded at a few nanometer distance from the free surface of titania/silica multilayers using low energy ion beam synthesis. Transmission electron microscopy shows the presence of 3 nm-sized crystalline particles. Reflectance spectroscopy on these composite substrates shows an increase of the light capture efficiency in the visible range. This behaviour is interpreted as a synergistic effect between plasmon polariton resonance and Fabry-Perot interferences. Plasmon-resonant Raman spectroscopy is deeply used to analyze, on one hand confinement of vibrations and electronic excitations in Ag NPs, and on the other hand coupling of polar TiO2 phonons with injected photo-generated carriers. It is shown how these new Ag/TiO2 nanocomposite films appear as very promising to enhance the efficiency and enlarge the spectral sensitivity of plasmo-electronics devices. PMID:26198669

  14. Enhancing carrier generation in TiO2 by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interference

    NASA Astrophysics Data System (ADS)

    Cacciato, Giuseppe; Bayle, Maxime; Pugliara, Alessandro; Bonafos, Caroline; Zimbone, Massimo; Privitera, Vittorio; Grimaldi, Maria Grazia; Carles, Robert

    2015-08-01

    Silver nanoparticles have been embedded at a few nanometer distance from the free surface of titania/silica multilayers using low energy ion beam synthesis. Transmission electron microscopy shows the presence of 3 nm-sized crystalline particles. Reflectance spectroscopy on these composite substrates shows an increase of the light capture efficiency in the visible range. This behaviour is interpreted as a synergistic effect between plasmon polariton resonance and Fabry-Perot interferences. Plasmon-resonant Raman spectroscopy is deeply used to analyze, on one hand confinement of vibrations and electronic excitations in Ag NPs, and on the other hand coupling of polar TiO2 phonons with injected photo-generated carriers. It is shown how these new Ag/TiO2 nanocomposite films appear as very promising to enhance the efficiency and enlarge the spectral sensitivity of plasmo-electronics devices.Silver nanoparticles have been embedded at a few nanometer distance from the free surface of titania/silica multilayers using low energy ion beam synthesis. Transmission electron microscopy shows the presence of 3 nm-sized crystalline particles. Reflectance spectroscopy on these composite substrates shows an increase of the light capture efficiency in the visible range. This behaviour is interpreted as a synergistic effect between plasmon polariton resonance and Fabry-Perot interferences. Plasmon-resonant Raman spectroscopy is deeply used to analyze, on one hand confinement of vibrations and electronic excitations in Ag NPs, and on the other hand coupling of polar TiO2 phonons with injected photo-generated carriers. It is shown how these new Ag/TiO2 nanocomposite films appear as very promising to enhance the efficiency and enlarge the spectral sensitivity of plasmo-electronics devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02406d

  15. Synthesis, characterization and degradation of Bisphenol A using Pr, N co-doped TiO 2 with highly visible light activity

    NASA Astrophysics Data System (ADS)

    Yang, Juan; Dai, Jun; Li, Jiantong

    2011-08-01

    Praseodymium and nitrogen co-doped titania (Pr/N-TiO 2) photocatalysts, which could degrade Bisphenol A (BPA) under visible light irradiation, were prepared by the modified sol-gel process. Tetrabutyl titanate, urea and praseodymium nitrate were used as the sources of titanium, nitrogen and praseodymium, respectively. The resulting materials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption isotherm and Fourier transform infrared spectra (FTIR). It was found that Pr doping inhibited the growth of crystalline size and the transformation from anatase to rutile. The degradation of BPA under visible light illumination was taken as probe reaction to evaluate the photo-activity of the co-doped photocatalyst. In our experiments, the optimal dopant amount of Pr was 1.2 mol% and the calcination temperature was 500 °C for the best photocatalytic activity. Pr/N-TiO 2 samples exhibited enhanced visible-light photocatalytic activity compared to N-TiO 2, undoped TiO 2 and commercial P25. The nitrogen atoms were incorporated into the crystal of titania and could narrow the band gap energy. Pr doping could slow the radiative recombination of photogenerated electrons and holes in TiO 2. The improvement of photocatalytic activity was ascribed to the synergistic effects of nitrogen and Pr co-doping.

  16. A mini-review on rare earth metal-doped TiO2 for photocatalytic remediation of wastewater.

    PubMed

    Saqib, Najm Us; Adnan, Rohana; Shah, Irfan

    2016-08-01

    Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst. PMID:27335012

  17. Synthesis of Cu-Doped Mixed-Phase TiO2 with the Assistance of Ionic Liquid by Atmospheric-Pressure Cold Plasma

    NASA Astrophysics Data System (ADS)

    Zhan, Zhibin; Di, Lanbo; Zhang, Xiuling; Li, Yanchun

    2016-05-01

    An atmospheric-pressure dielectric barrier discharge (DBD) gas-liquid cold plasma was employed to synthesize Cu-doped TiO2 nanoparticles in an aqueous solution with the assistance of [C2MIM]BF4 ionic liquid (IL) and using air as the working gas. The influences of the discharge voltage, IL and the amount of copper nitrite were investigated. X-ray diffraction, N2 adsorption-desorption measurements and UV-Vis spectroscopy were adopted to characterize the samples. The results showed that the specific surface area of TiO2 was promoted with Cu-doping (from 57.6 m2·g‑1 to 106.2 m2·g‑1 with 3% Cu-doping), and the content of anatase was increased. Besides, the band gap energy of TiO2 with Cu-doping decreased according to the UV-Vis spectroscopy test. The 3%Cu-IL-TiO2 samples showed the highest efficiency in degrading methylene blue (MB) dye solutions under simulated sunlight with an apparent rate constant of 0.0223 min‑1, which was 1.2 times higher than that of non-doped samples. According to the characterization results, the reasons for the high photocatalytic activity were discussed. supported by National Natural Science Foundation of China (Nos. 21173028, 11505019), the Science and Technology Research Project of Liaoning Provincial Education Department (No. L2013464), the Scientific Research Foundation for the Doctor of Liaoning Province (No. 20131004), the Program for Liaoning Excellent Talents in University (No. LR2012042), and Dalian Jinzhou New District Science and Technology Plan Project (No. KJCX-ZTPY-2014-0001)

  18. Development of the IR laser pyrolysis for the synthesis of iron-doped TiO 2 nanoparticles: Structural properties and photoactivity

    NASA Astrophysics Data System (ADS)

    Alexandrescu, R.; Morjan, I.; Scarisoreanu, M.; Birjega, R.; Fleaca, C.; Soare, I.; Gavrila, L.; Ciupina, V.; Kylberg, W.; Figgemeier, E.

    2010-03-01

    The preparation of TiO 2-based nanoparticles of closely controlled sizes and purity gives rise to considerable interest in the frame of environmental applications, e.g. in photocatalysis. When nanoparticles instead of their bulk counterpart are used the synthesis method plays a fundamental role in defining specific structural properties. Between the different gas-phase synthesis techniques, the CO 2 laser pyrolysis is a versatile method allowing for the preparation of nanostructures of various chemical compositions. Here we demonstrate that pure and Fe-doped TiO 2 nanoparticles with rather low Fe concentration may be prepared by applying the sensitized IR laser pyrolysis to a gas mixtures containing titanium tetrachloride, air and iron pentacarbonyl (vapors). The structures of TiO 2-based particles were systematically investigated by X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy, selected area electron diffraction and X-ray Photoelectron Spectroscopy. Depending on the synthesis parameters, the nanoparticle system contains mixtures of anatase and rutile, with a preponderance of the anatase phase. Higher rutile proportion was found in the iron-doped samples. Mean particle diameters of around 14 nm and 12 nm were estimated for undoped and doped anatase titania, respectively. From UV-Vis diffuse reflectance spectra, higher absorbance and red shifted absorption were evidenced at higher amount of doped iron. Preliminary evaluation tests of the UV photoactivity of samples were performed by using the scanning electrochemical microscopy for determining the evolution of the oxygen consumption in the presence of IV-chlorophenol. They show that the undoped nano titania samples perform better than the reference P25 Degussa sample. A drop of the nano-titania photoactivity as a consequence of Fe doping was observed. Possible reasons of this effect are tentatively discussed.

  19. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2.

    PubMed

    Triantis, T M; Fotiou, T; Kaloudis, T; Kontos, A G; Falaras, P; Dionysiou, D D; Pelaez, M; Hiskia, A

    2012-04-15

    In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO(2) (N-TiO(2)) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO(2), Kronos and reference TiO(2) nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO(2) followed by N-TiO(2) with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO(2) nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO(2) for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO(2) displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO(2)(-), NO(3)(-) and NH(4)(+)) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light. PMID:22169146

  20. A Facile Molecular Precursor-based Synthesis of Ag2 Se Nanoparticles and Its Composites with TiO2 for Enhanced Photocatalytic Activity.

    PubMed

    Mishra, Shashank; Du, Dan; Jeanneau, Erwann; Dappozze, Frederic; Guillard, Chantal; Zhang, Jinlong; Daniele, Stéphane

    2016-06-01

    The reactions of different silver(I) reagents AgX (X(-) =iodide, trifluoroacetate, triflate) with selenoethers R2 Se (R=Me, tBu) in a variety of solvents were investigated in relation with their use as precursors for Ag2 Se nanomaterials. Different reaction conditions led to different reactivities and afforded either molecular complexes or metal selenide nanoparticles. The reactions leading to in situ formation of the metal selenide nanoparticles were then extended in the presence of commercial TiO2 (P25) to prepare silver selenide-titania nanocomposites with different Ag/Ti ratios. These nanocomposites, well characterized by elemental analysis (Ag, Se), PXRD, TEM, BET, XPS and UV/Vis studies, were investigated as photocatalysts for the degradation of formic acid (FA) solution. The xAg2 Se-TiO2 nanocomposites (x=0.01, 0.13 and 0.25 mol %) exhibited a much higher catalytic activity as compared to P25, which is an established benchmark for the photocatalysis under UV light, and retained a good photocatalytic stability after recycling for several times. PMID:27123779

  1. Coating effect of electrospun nanofibers of Nb-doped TiO2 mixed in photoelectrode of dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Horie, Yuji; Deguchi, Makoto; Guo, Shirong; Aoki, Keisuke; Nomiyama, Teruaki

    2014-01-01

    Electrospun nanofibers (NFs) of Nb doped TiO2 (TNO) were added as a conductive agent to TiO2 mesoporous layer in dye sensitized solar cells. In order to improve the mobility of carriers in NFs by reducing the barrier at grain boundaries among constituent nanoparticles in NFs, the surface of TNO-NFs was coated with a thin TNO layer by pulsed laser deposition with changing the deposition time td. It was found that the inter-grain space was filled first at td ≤ 5 min, and the diffusion velocity vD of carriers was increased by more than 10 times. Since Jsc showed an increase of ˜15% while vD and the electron lifetime τe decreased at td > 10 min, the carrier injection from dye/TiO2 nanoparticles to TNO-NFs was considered to be promoted.

  2. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation

    NASA Astrophysics Data System (ADS)

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-01

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h-1 g-1 has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature.We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and

  3. Green synthetic approach for Ti3+ self-doped TiO2-x nanoparticles with efficient visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Gao, Shanmin; Xu, Hui; Lou, Zaizhu; Wang, Wenjun; Huang, Baibiao; Dai, Ying

    2013-02-01

    Rice-shaped Ti3+ self-doped TiO2-x nanoparticles were synthesized by mild hydrothermal treatment of TiH2 in H2O2 aqueous solution. The structure, crystallinity, morphology, and other properties of the as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microcopy and X-ray photoelectron spectra. Electron paramagnetic resonance spectra confirm the presence of high concentration of paramagnetic Ti3+ in the bulk and surface of the as-prepared samples. The particles showed a strong absorption across the UV to the visible light region and retained their light-blue color upon storage in ambient atmosphere or water for one month at 40 °C. The formation mechanism of Ti3+ self-doped TiO2-x nanoparticles was discussed. Under visible light irradiation, the samples exhibit higher photocatalytic activity for hydrogen evolution and photooxidation of methylene blue than that of the commercial P25 TiO2 nanoparticles. The sample obtained at 160 °C for 27 h showed a 9-fold enhancement for the visible light decomposition of methylene blue and 12.5 times higher for H2 production in comparison to P25 TiO2. The samples also showed an excellent cycling stability of the photocatalytic activity.Rice-shaped Ti3+ self-doped TiO2-x nanoparticles were synthesized by mild hydrothermal treatment of TiH2 in H2O2 aqueous solution. The structure, crystallinity, morphology, and other properties of the as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microcopy and X-ray photoelectron spectra. Electron paramagnetic resonance spectra confirm the presence of high concentration of paramagnetic Ti3+ in the bulk and surface of the as-prepared samples. The particles showed a strong absorption across the UV to the visible light region and retained their light-blue color upon storage in ambient atmosphere or water for one month at 40 °C. The

  4. A study of the impurity structure for 3d 3 (Cr 3+ and Mn 4+) ions doped into rutile TiO 2 crystal

    NASA Astrophysics Data System (ADS)

    Açıkgöz, Muhammed

    2012-02-01

    The local environment around 3d 3 (Cr 3+ and Mn 4+) ions doped into rutile TiO 2 crystals has been investigated using superposition model (SPM) analysis. The zero-field splitting (ZFS) parameters (ZFSPs) D and E are modeled for the Cr 3+ and Mn 4+ ions at both the substitutional Ti sites with local symmetry orthorhombic D2h and the interstitial sites (ISs) with the same symmetry. Several model parameter sets are adopted so as to acquire the best agreement between the calculated ZFSPs and those measured by electron magnetic resonance (EMR). The feasible values of the structural distortions (Δ RY, Δ RXZ and Δ θ) resulting from dopant Cr 3+ and Mn 4+ ions are determined. As a result, it is confirmed that Mn 4+ ions substitute for Ti 4+ sites in rutile TiO 2 crystal; however, it is suggested that Cr 3+ ions may replace at not only Ti 4+ site but also IS.

  5. Extremely fast dark adsorption rate of carbon and nitrogen co-doped TiO2 prepared by a relatively fast, facile and low-cost microwave method

    NASA Astrophysics Data System (ADS)

    Du, Chun; Zhou, Jiangshan; Li, Fangzhou; Li, Wei; Wang, Yinzhen; He, Qinyu

    2016-07-01

    A facile and low-cost microwave method was used to prepare C and N co-doped TiO2 in just 8 min. The prepared samples were thoroughly characterized and were found to have favourable features such as surface adsorption of pollutants and photocatalysis. The rapid decomposition of CH5N3HCl under microwave irradiation led to mesopores and surface roughness in the as-prepared particles, resulting in large surface adsorption of pollutant and good photodegradation. The best sample is the one with the ratio of TiO2/CH2N3HCl at 3:1, which adsorbed 86.3 % of a methylene orange (MO) solution (20 mg L-1) in 10 min.

  6. Highly efficient and recyclable triple-shelled Ag@Fe3O4@SiO2@TiO2 photocatalysts for degradation of organic pollutants and reduction of hexavalent chromium ions.

    PubMed

    Su, Jianwei; Zhang, Yunxia; Xu, Sichao; Wang, Shuan; Ding, Hualin; Pan, Shusheng; Wang, Guozhong; Li, Guanghai; Zhao, Huijun

    2014-05-21

    Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues. PMID:24710730

  7. Synergy of metal and nonmetal dopants for visible-light photocatalysis: a case-study of Sn and N co-doped TiO2.

    PubMed

    Zhuang, Huaqiang; Zhang, Yingguang; Chu, Zhenwei; Long, Jinlin; An, Xiaohan; Zhang, Hongwen; Lin, Huaxiang; Zhang, Zizhong; Wang, Xuxu

    2016-04-14

    This paper mainly focuses on the synergistic effect of Sn and N dopants to enhance the photocatalytic performance of anatase TiO2 under visible light or simulated solar light irradiation. The Sn and N co-doped TiO2 (SNT-x) photocatalysts were successfully prepared by the facile sol-gel method and the post-nitridation route in the temperature range of 400-550 °C. All the as-prepared samples were characterized in detail by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, transmission electron microscopy, X-ray photoelectron and electron spin resonance spectroscopy and photoelectrochemical measurements. The characterization results reveal that the co-incorporation of Sn and N atoms remarkably modifies the electronic structure of TiO2, which gives rise to a prominent separation of photogenerated charge carriers and more efficient interfacial charge-transfer reactions in a photocatalytic process. The enhanced photocatalytic activity is attributed to the intensified active oxygen species including hydroxyl radicals (˙OH) and superoxide anion radicals (O2˙(-)) for degradation of organic pollutants. And the result of photocatalytic hydrogen production further confirms the existence of the synergistic effect in the SNT-x samples, because they exhibit higher photocatalytic activity than the sum of N/TiO2 and Sn/TiO2. This work provides a paradigm to consolidate the understanding of the synergistic effect of metal and non-metal co-doped TiO2 in domains of photocatalysis and photoelectrochemistry. PMID:26996319

  8. Effects of cerium dopant concentration on structural properties and photocatalytic activity of electrospun Ce-doped TiO2 nanofibers

    NASA Astrophysics Data System (ADS)

    Worayingyong, Attera; Sang-urai, S.; Smith, M. F.; Maensiri, Santi; Seraphin, S.

    2014-05-01

    Electrospun {TiO}_2 and Ce-doped {TiO}_2 nanofibers were prepared with 0.5, 2.0 and 8.0 % weight Ce. The structural properties and phase composition were characterized using high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction and X-ray absorption near edge spectroscopy (XANES) at the Ti K-edge. The undoped nanofibers are composed of an assembly of {TiO}_2 nanoparticles and their crystal structure is a mixture of anatase and rutile phases with an anatase:rutile volume ratio close to 3:1. As Ce is introduced, the nanoparticles decrease in size and the rutile phase volume decreases. Ce {L}_3 -edge XANES probed the local structure of Ce dopants. At 0.5 % Ce, most Ce ions are incorporated in the {Ce}^{3+} charge state but, at 2 % Ce, the majority are {Ce}^{4+} . Visible light absorption indicated that {Ce}^{3+} act as shallow acceptors that only participate in absorption of wavelengths below 420 nm but {Ce}^{4+} impurity states are associated with absorption of wavelengths up to 550 nm. Photocatalytic performance of the nanofibers was assessed by measuring the degradation of adsorbed Rhodamine B in aqueous solution under visible and ultraviolet light. The 0.5 % Ce-doped {TiO}_2 nanofiber showed the best visible-light photocatalytic activity, which is probably due to the majority presence of {Ce}^{3+} . At higher Ce concentration, the photocatalytic reaction rate was lower than undoped nanofibers, indicating that recombination at the {Ce}^{4+} sites is rate limiting.

  9. Er3+ -doped anatase TiO2 nanocrystals: crystal-field levels, excited-state dynamics, upconversion, and defect luminescence.

    PubMed

    Luo, Wenqin; Fu, Chengyu; Li, Renfu; Liu, Yongsheng; Zhu, Haomiao; Chen, Xueyuan

    2011-11-01

    A comprehensive survey of electronic structure and optical properties of rare-earth ions embedded in semiconductor nanocrystals (NCs) is of vital importance for their potential applications in areas as diverse as luminescent bioprobes, lighting, and displays. Er3+ -doped anatase TiO2 NCs, synthesized via a facile sol-gel solvothermal method, exhibit intense and well-resolved intra-4f emissions of Er3+ . Crystal-field (CF) spectra of Er3+ in TiO2 NCs are systematically studied by means of high-resolution emission and excitation spectra at 10-300 K. The CF analysis of Er3+ assuming a site symmetry of C(2v) yields a small root-mean-square deviation of 25.1 cm(-1) and reveals the relatively large CF strength (549 cm(-1) ) of Er3+, thus verifying the rationality of the C(2v) symmetry assignment of Er3+ in anatase TiO2 NCs. Based on a simplified thermalization model for the temperature-dependent photoluminescence (PL) dynamics from (4) S(3/2) , the intrinsic radiative luminescence lifetimes of (4) S(3/2) and (2) H(11/2) are experimentally determined to be 3.70 and 1.73 μs, respectively. Green and red upconversion (UC) luminescence of Er3+ can be achieved upon laser excitation at 974.5 nm. The UC intensity of Er3+ in Yb/Er-codoped NCs is found to be about five times higher than that of Er-singly-doped counterparts as a result of efficient Yb3+ sensitization and energy transfer upconversion (ETU) evidenced by its distinct UC luminescence dynamics. Furthermore, the origin of defect luminescence is revealed based on the temperature-dependent PL spectra upon excitation above the TiO2 bandgap at 325 nm. PMID:21932290

  10. Effect of Sn doping on the structural, optical and electrical properties of TiO2 films prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Arunachalam, A.; Dhanapandian, S.; Manoharan, C.

    2016-02-01

    In this work, highly oriented pure and Tin-doped Titanium dioxide (Sn-doped TiO2) with porous nature photoelectrodes were deposited on ITO glass plates using spray pyrolysis technique. The XRD pattern revealed the formation of anatase TiO2 with the maximum intensity of (101) plane while doping 6 at% of Sn. The morphological studies depicted the porous nature with the uniform arrangement of small-sized grains. The presence of tin confirmed with the EDX spectra. The size of particles of 13 nm was observed from High Resolution Transmission Electron Microscopy (HR-TEM) analysis. The average transmittance was about 85% for the doped photoelectrode and was observed for the photoelectrode deposited with 6 at% of tin, with decreased energy band gap. The PL study showed the emission peak at 391 nm. The maximum carrier concentration and Hall mobility was observed for the photoelectrode deposited with 6 at% of tin. With these studies, the DSSCs were prepared separately with the dye extracted from Hibiscus Rosasinesis and Hibiscus Surttasinesis and their efficiency was maximum for the DSSC prepared with 6 at% of tin.

  11. The structural studies of Ag containing TiO2-SiO2 gels and thin films deposited on steel

    NASA Astrophysics Data System (ADS)

    Adamczyk, Anna; Rokita, Magdalena

    2016-06-01

    FTIR spectroscopic structural studies of titania-silica monolith samples as well as thin films deposited on steel were described in this work. Thin films were synthesized by the sol-gel method applying the dip coating as separate one-component TiO2 and/or SiO2 layers or as two-component TiO2-SiO2 thin films. Silver nanoparticles were incorporated into the structure from pure SiO2 sol, deposited then as an additional layer in those hybrid multilayers systems. Except the spectroscopic studies, XRD diffraction, SEM microscopy with EDX analysis and AFM microscopy were applied. The structural studies allow to describe and compare the structure and the morphology of thin films, as well those Ag free as Ag containing ones, also by the comparison with the structure of bulk samples. In FTIR spectra, the band observed at about 613 cm-1 can be connected with the presence of the non-tetrahedral cation in the structure and is observed only in the spectra of Ag containing bulk samples and thin films. The bands at 435-467 cm-1 are due to the stretching vibrations of Ti-O bonds or as well to the bending vibrations of O-Si-O one. In the ranges of 779-799 cm-1 and 1027-1098 cm-1, the bands ascribed to the symmetric stretching vibrations and asymmetric vibrations of Si-O-Si connections, respectively, are observed. SEM and AFM images gave the information on the microstructure and the topography of samples surface. XRD measurements confirmed the presence of only amorphous phase in samples up to 500 °C and allowed to observe the tendency of their crystallization.

  12. Investigation of antileishmanial activities of Tio2@Ag nanoparticles on biological properties of L. tropica and L. infantum parasites, in vitro.

    PubMed

    Allahverdiyev, Adil M; Abamor, Emrah Sefik; Bagirova, Melahat; Baydar, Serap Yesilkir; Ates, Sezen Canim; Kaya, Figen; Kaya, Cengiz; Rafailovich, Miriam

    2013-09-01

    Leishmaniasis is a public health problem which is caused by protozoon parasites belonging to Leishmania species. The disease threatens approximately 350 million people in 98 countries all over the world. Cutaneous Leishmaniasis (CL) and Visceral Leishmaniasis (VL) are the mostly commonly seen forms of the disease. Treatment of the disease has remained insufficient since current antileishmanial drugs have several disadvantages such as toxicity, costliness and drug-resistance. Therefore, there is an immediate need to search for new antileishmanial compounds. TiO2@Ag nanoparticles (TiAg-Nps) have been demonstrated as promising antimicrobial agents since they provide inhibition of several types of bacteria. The basic antimicrobial mechanism of TiAg-Nps is the generation of reactive oxygen species (ROS). Even though Leishmania parasites are sensitive to ROS, there is no study in literature indicating antileishmanial activities of TiAg-Nps. Herein, in this study, TiAg-Nps are shown to possess antileishmanial effects on Leishmania tropica and Leishmania infantum parasites by inhibiting their biological properties such as viability, metabolic activity, and survival within host cells both in the dark and under visible light. The results indicate that TiAg-Nps decreased viability values of L. tropica, and L. infantum promastigotes 3- and 10-fold, respectively, in the dark, while these rates diminished approximately 20-fold for each species in the presence of visible light, in contrast to control. On the other hand, non-visible light-exposed TiAg-Nps inhibited survival of amastigotes nearly 2- and 2.5-fold; while visible light-exposed TiAg-Nps inhibited 4- and 4.5-fold for L. tropica and L. infantum parasites, respectively. Consequently, it was determined that non-visible light-exposed TiAg-Nps were more effective against L. infantum parasites while visible light-exposed TiAg-Nps exhibited nearly the same antileishmanial effect against both species. Therefore, we think that a

  13. Enhanced Electrorheological Performance of Nb-Doped TiO2 Microspheres Based Suspensions and Their Behavior Characteristics in Low-Frequency Dielectric Spectroscopy.

    PubMed

    Guo, Xiaosong; Chen, Yulu; Su, Ming; Li, Dong; Li, Guicun; Li, Chengdong; Tian, Yu; Hao, Chuncheng; Lei, Qingquan

    2015-12-01

    Titanium dioxide and Nb-doped titanium dioxide microspheres with the same size were fabricated by a simple sol-gel method, and the formation mechanism of Nb-doped titanium dioxide microspheres was proposed. Titanium dioxide and Nb-doped titanium dioxide microspheres were adopted as dispersed materials for electrorheological (ER) fluids to investigate the influence of the charge increase introduced by Nb doping on the ER activity. The results showed that Nb doping could effectively enhance the ER performance. Combining with the analysis of dielectric spectroscopy, it was found that the interface polarization of Nb-doped TiO2 ER fluid was larger than that of TiO2 ER fluid, which might be caused by more surface charges in Nb-TiO2 microspheres due to Nb(5+) doping and resulting in enhancement of electric field force and strengthening of fibrous structure. In addition, by comparing and analyzing the permittivity curves of Nb-TiO2/LDPE solid composite and Nb-TiO2/silicone-oil fluid composite, it could be concluded that the enhancement of permittivity at low frequency resulted from the increase of the order degree of dispersed particles in ER fluid rather than from the quasi-dc (QDC) behavior. Moreover, the absolute value of slope of permittivity curves (K) at 0.01 Hz could be utilized as the standard for judging the ability to maintain the chainlike structure. The relationships between polarizability of dispersed particles, dielectric spectrum, parameter K, and ER properties were discussed in detail. PMID:26570989

  14. Efficient photocatalytic degradation of organic pollutants by magnetically recoverable nitrogen-doped TiO2 nanocomposite photocatalysts under visible light irradiation.

    PubMed

    Hamzezadeh-Nakhjavani, Sahar; Tavakoli, Omid; Akhlaghi, Seyed Parham; Salehi, Zeinab; Esmailnejad-Ahranjani, Parvaneh; Arpanaei, Ayyoob

    2015-12-01

    Preparation of novel nanocomposite particles (NCPs) with high visible-light-driven photocatalytic activity and possessing recovery potential after advanced oxidation process (AOP) is much desired. In this study, pure anatase phase titania (TiO2) nanoparticles (NPs) as well as three types of NCPs including nitrogen-doped titania (TiO2-N), titania-coated magnetic silica (Fe3O4 cluster@SiO2@TiO2 (FST)), and a novel magnetically recoverable TiO2 nanocomposite photocatalyst containing nitrogen element (Fe3O4 cluster@SiO2@TiO2-N (FST-N)) were successfully synthesized via a sol-gel process. The photocatalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) with an energy-dispersive X-ray (EDX) spectroscopy analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM). The photocatalytic activity of as-prepared samples was further investigated and compared with each other by degradation of phenol, as a model for the organic pollutants, in deionized (DI) water under visible light irradiation. The TiO2-N (55 ± 1.5%) and FST-N (46 ± 1.5%) samples exhibited efficient photocatalytic activity in terms of phenol degradation under visible light irradiation, while undoped samples were almost inactive under same operating conditions. Moreover, the effects of key operational parameters, the optimum sample calcination temperature, and reusability of FST-N NCPs were evaluated. Under optimum conditions (calcination temperature of 400 °C and near-neutral reaction medium), the obtained results revealed efficient degradation of phenol for FST-N NCPs under visible light irradiation (46 ± 1.5%), high yield magnetic separation and efficient reusability of FST-N NCPs (88.88% of its initial value) over 10 times reuse. PMID:26206125

  15. Facile preparation of N-doped TiO2 at ambient temperature and pressure under UV light with 4-nitrophenol as the nitrogen source and its photocatalytic activities.

    PubMed

    Horikoshi, Satoshi; Shirasaka, Yutaro; Uchida, Hiroshi; Horikoshi, Natsuko; Serpone, Nick

    2016-08-01

    To date syntheses of nitrogen-doped TiO2 photocatalysts (TiO2-xNx) have been carried out under high temperatures and high pressures with either NH3 or urea as the nitrogen sources. This article reports for the first time the facile preparation of N-doped TiO2 (P25 titania) in aqueous media at ambient temperature and pressure under inert conditions (Ar- and N2-purged dispersions) with 4-nitrophenol (or 4-nitrobenzaldehyde) as the nitrogen source. The resulting N-doped P25 TiO2 materials were characterized by UV/Vis and X-ray photoelectron spectroscopies (XPS) that confirmed the presence of nitrogen within the photocatalyst; X-ray diffraction (XRD) techniques confirmed the crystalline phases of the doped material. The photocatalytic activity of N-doped TiO2 was assessed through examining the photodegradation of 4-chlorophenol in aqueous media and iso-propanol as a volatile pollutant under UV/Vis and visible-light irradiation. Under visible light irradiation, undoped P25 was inactive contrary to N-doped P25 that successfully degraded 95% of the 4-chlorophenol (after 10 h) and 23% of iso-propanol (after 2.5 h). PMID:27444263

  16. Comparison of the killing effects between nitrogen-doped and pure TiO2 on HeLa cells with visible light irradiation

    PubMed Central

    2013-01-01

    The killing effect of nitrogen-doped titanium dioxide (N-TiO2) nanoparticles on human cervical carcinoma (HeLa) cells by visible light photodynamic therapy (PDT) was higher than that of TiO2 nanoparticles. To study the mechanism of the killing effect, the reactive oxygen species produced by the visible-light-activated N-TiO2 and pure-TiO2 were evaluated and compared. The changes of the cellular parameters, such as the mitochondrial membrane potential (MMP), intracellular Ca2+, and nitrogen monoxide (NO) concentrations after PDT were measured and compared for N-TiO2- and TiO2-treated HeLa cells. The N-TiO2 resulted in more loss of MMP and higher increase of Ca2+ and NO in HeLa cells than pure TiO2. The cell morphology changes with time were also examined by a confocal microscope. The cells incubated with N-TiO2 exhibited serious distortion and membrane breakage at 60 min after the PDT. PMID:23433090

  17. Photocatalytic Antibacterial Performance of Glass Fibers Thin Film Coated with N-Doped SnO2/TiO2

    PubMed Central

    Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

    2014-01-01

    Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600°C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency. PMID:24693250

  18. Broadband sensitization of downconversion phosphor YPO4 by optimizing TiO2 substitution in host lattice co-doped with Pr3+-Yb3+ ion-couple

    NASA Astrophysics Data System (ADS)

    Li, Kai-Yu; Liu, Li-Ying; Wang, Ru-Zhi; Xiao, Si-Guo; Zhou, Hua; Yan, Hui

    2014-03-01

    This study demonstrates a feasible and efficient route to alleviate the absorption problem of the terrestrial solar spectrum and enhance broadband luminescence from a promising down conversion powder phosphor YPO4 co-doped with Pr3+-Yb3+ lanthanide ion-couple: incorporating a third sensitizing transition metal ion, e.g., Ti4+. The x-ray powder diffraction results confirm the lattice substitution by the solid-state reaction doping rather than the formation of any secondary phase. The emission spectral results and the luminescence decay curve analysis show that the downconversion luminescence can be enhanced by 200%-300% and the quantum efficiency enhanced by more than 20% at the wavelength of around 980 nm, the best response spectrum for Si-based solar cells, by optimizing TiO2 doping concentration at 7 mol. %.

  19. Photocatalytic antibacterial performance of glass fibers thin film coated with N-doped SnO2/TiO2.

    PubMed

    Kongsong, Peerawas; Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

    2014-01-01

    Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600 °C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency. PMID:24693250

  20. Enhanced photocatalytic activity of nanocomposites of TiO2 doped with Zr, Y or Ce polyoxometalates for degradation of methyl orange dye.

    PubMed

    Khoshnavazi, Roushan; Fereydouni, Shler; Bahrami, Leila

    2016-01-01

    The synergistic effect of polyoxometalate (POM) and metal-doped TiO2 (metal = Zr, Y and Ce) was examined, to fabricate nanocomposites with enhanced photocatalytic activities toward the degradation of methyl orange (MO), as a model textile dye. A series of new nanocomposites, containing different loading amounts of H9Na3[WZn3(H2O)2(ZnW9O34)2].24H2O (HZnW) (10-30%) on each of the metal-doped TiO2 nanoparticles, were synthesized using impregnation method. The morphology and crystal phase of the as-prepared nanocomposites were investigated by various characterization techniques: Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and diffuse reflectance spectroscopy, indicating that the HZnW and metal-doped TiO2 had been successfully incorporated into the nanocomposite structure. The effects of parameters such as loading amount of HZnW, catalyst dose, pH and initial concentration of dye solution were investigated on the degradation kinetics and it was interestingly found that the prepared nanocomposites could efficiently degrade the MO dye in 5-7 min under UV light irradiation. The best results were obtained for the HZnW-Zr-TiO2 among the different nanocomposites. Also, control studies showed the superior photocatalytic properties of composites compared to that of the individual components. The facile preparation and their improved photocatalytic activities suggest that these materials can have a promising future for water and wastewater purifications. PMID:27054748