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Sample records for ag doped tio2

  1. Synthesis and characterization of Ag doped TiO2 heterojunction films and their photocatalytic performances

    NASA Astrophysics Data System (ADS)

    Demirci, Selim; Dikici, Tuncay; Yurddaskal, Metin; Gultekin, Serdar; Toparli, Mustafa; Celik, Erdal

    2016-12-01

    In this study, undoped and silver (Ag) doped titanium dioxide (TiO2) films were successfully synthesized by sol-gel spin coating technique on the Si substrates. Photocatalytic activities of the TiO2 films with different Ag content were investigated for the degradation of methylene blue (MB) under UV light irradiation. The crystal phase structure, surface morphology, chemical and optical properties of Ag-doped TiO2 films were characterized using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometer, and FTIR spectrophotometer. The results showed that the Ag-doped TiO2 films calcined at 500 °C had the crystalline anatase phases and the surface morphologies with some cracks. Ag substitution into TiO2 matrix enhanced the photocatalytic activity of TiO2 films under UV light irradiation as compared to the undoped TiO2 film. Furthermore, the results indicated that the 0.7% Ag doped TiO2 film exhibited a superior photocatalytic activity than that of undoped and other Ag-doped TiO2 films. This study demonstrated the potential of an application of Ag doped films to efficiently treat dissolved organic contaminants in water.

  2. 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.

  3. 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.

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

    PubMed

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

    2012-11-01

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

  5. Synthesis, characterization and photocatalytic behavior of Ag doped TiO2 thin film

    NASA Astrophysics Data System (ADS)

    Bensouici, F.; Souier, T.; Dakhel, A. A.; Iratni, A.; Tala-Ighil, R.; Bououdina, M.

    2015-09-01

    In this study, structure, microstructure, optical properties and photocatalytic degradation of Rhodamine B (RhB) have been investigated in an aqueous heterogeneous media containing pure and Ag doped TiO2 nanostructures thin films which were prepared by a simple sol-gel route. Thermal analysis demonstrated that Ag content decreased the temperature of anatase-to-rutile phase transformation. X-ray diffraction analysis confirmed that the prepared nanostructures crystallize within anatase-type structure and that the dopant Ag ions were not fully incorporated within TiO2 host lattice, meanwhile both the refractive index and optical band gap were affected by Ag concentration. The photodegradation of Rhodamine B under UV-C radiation by using pure and Ag-doped TiO2 nanostructures showed that Ag played an important role in a significant improvement of the photodegradation efficiency and that the optimum content of Ag ions was found to be 0.5% molar ratio.

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

    PubMed Central

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

    2013-01-01

    Summary This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only. PMID:23844339

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

    PubMed

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

    2013-01-01

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

  8. Enhancement of stability of N-doped TiO2 photocatalysts with Ag loading

    NASA Astrophysics Data System (ADS)

    Gao, Yuanpeng; Fang, Pengfei; Chen, Feitai; Liu, Yang; Liu, Zhi; Wang, Dahai; Dai, Yiqun

    2013-01-01

    Various contents of Ag nanoparticles were successfully introduced into the N-doped TiO2 photocatalysts via a hydrothermal procedure in the silver-ammonia solutions with different Ag concentrations. Effects of Ag loading on the structure and properties of N-doped TiO2 photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, fluorescence spectroscopy (FL), UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and N2 physical adsorption analysis. The relationship between the stability of N dopants in TiO2 lattice and the Ag loading content was investigated for the first time. The results confirm that Ag nanoparticles loading on TiO2 surfaces significantly restrain the escape of the N dopants from the oxide during the hydrothermal process, and the escape rate of N dopants decreased gradually with the increase of Ag loading amount. The dependence of photocatalytic activity on Ag content was also investigated through degradation of rhodamine B (RhB) under visible light irradiation. It was found that the photocatalytic activity increases gradually with increasing Ag content first, and then decreases after exceeding the optimal Ag content. Therefore, the photocatalytic activity of Ag/N co-modified TiO2 photocatalysts can be adjusted by the Ag content.

  9. Formaldehyde degradation by photocatalytic Ag-doped TiO2 film of glass fiber roving.

    PubMed

    Ubolchonlakate, Kornkanok; Sikong, Lek; Tontai, Tienchai

    2010-11-01

    The photocatalytic Ag doped TiO2 porous films were prepared by sol-gel method and dip coated on glass fiber roving. The sol composed of titanium (IV) isopropoxide, triethanolamine, ethanol and nitric acid followed by calcination of the film at 500 degrees C for 1 hour with a heating rate of 3 degrees C/min. The surface morphology and properties of synthesized TiO2 films were characterized by X-ray diffraction, atomic forced microscope and scanning electron microscope. A laboratory photocatalytic reactor was set up to carry out photoactivity of the prepared catalysts. The results show that TiO2-Ag and TiO2-Ag-TEA porous films give highest rate of formaldehyde gas degradation. It can be noted that triethanolamine exhibits two effects on TiO2 composite films; one is its effect on porous film structure and second is a reverse effect of hindrance of anatase growth.

  10. Ag-Si Co-doped TiO2 photocatalyst synthesized via a nonaqueous method.

    PubMed

    Chen, Qifeng; Shi, Weimei; Xu, Yao; Wu, Dong; Sun, Yuhan

    2010-11-01

    Ag-Si/TiO2 photocatalysts were synthesized in a nonaqueous system at 140 degrees C, and then annealed at different temperatures. The obtained photocatalysts were characterized by XRD, TEM, BET, TG-DTA, XPS, as well as UV-vis DRS. The results showed that All Ag-Si/TiO2 held an anatase phase and high thermal stability and the phase transformation from anatase to rutile was retarded to about 900 degrees C. The Ag-Si/TiO2 particles were highly mono-dispersed and the particles size became smaller compared to TiO2. Additionally, UV-vis light absorption shifted to visible region after Ag doping. Si weaved into the matrix of TiO2, while Ag dispersed on the surface of TiO2 particles. The visible light photocatalytic activity was evaluated by Rhodamine B (RhB) degradation in an aqueous solution under visible light irradiation. It was found that the photccatalytic activities of the obtained Ag-Si/TiO2 samples were all higher than those of pure TiO2 and Ag/TiO2, reaching the maximum at the Ag and Si content of 0.5 mol% and 20.0 mol%, respectively. The enhanced visible photocatalytic activity may be attributed to the simultaneous effects of silver and silicon co-doping.

  11. Disinfection of water using Pt- and Ag-doped TiO2 photocatalysts.

    PubMed

    Suri, Rominder P S; Thornton, Hilary M; Muruganandham, M

    2012-01-01

    In this article we have reported heterogeneous photocatalytic disinfection using pristine and Ag- and Pt-doped nano TiO2 under near-UV light and solar light irradiation. Disinfection experiments were conducted in slurry reactors with Escherichia coli, artificial light and sunlight. The influence of various amounts of Pt and Ag loading (0.5% to 5%) on the E. coli inactivation was examined and results indicated that 5% Pt-TiO2 and 0.5% Ag-TiO2 showed the highest photocatalytic E. coli inactivation. The Pt- and Ag-doped photocatalysts were characterized using XPS and TEM analysis. The influence of experimental parameters such as various photocatalysts, photocatalyst concentration, reactor geometry effect, pH and temperature on the photocatalytic disinfection was studied. The experimental results show that sunlight or near-UV light with TiO2 photocatalyst strongly inactivates E. coli. The Ag-TiO2 photocatalyst was the most efficient photocatalyst tested for bactericidal activity. A plausible mechanism ofphotocatalysed E. coli inactivation is discussed. In conclusion, the doped nano TiO2 photocatalysts is a potential candidate for E. coli inactivation.

  12. Antibacterial activities of Nd doped and Ag coated TiO2 nanoparticles under solar light irradiation.

    PubMed

    Bokare, Anuja; Sanap, Avinash; Pai, Mrinal; Sabharwal, Sushma; Athawale, Anjali A

    2013-02-01

    Nanosized (8-9 nm) Nd doped and Ag coated TiO(2) nanoparticles have been synthesized by sol-gel method. The physicochemical properties of these particles were investigated by X-ray diffraction (XRD), diffuse reflectance UV-visible (DRUV) spectra and Brunauer-Emmett-Teller (BET) surface area analysis. The antibacterial activities of the samples were studied for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) both, under the light and dark conditions. The results reveal that the extent of activity shows the order as undoped TiO(2)doped TiO(2)<Ag coated TiO(2). The mechanism of bactericidal action of the nanoparticles, in presence of sunlight has been explained with the help of microscopic analyses. The bacterial damage is observed to proceed through initial perforation of the cell, damage of cell wall and finally the bacterial death.

  13. 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).

  14. 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

  15. Antimicrobial effect of TiO2 doped with Ag and Cu on Escherichia coli and Pseudomonas putida

    NASA Astrophysics Data System (ADS)

    Angelov, O.; Stoyanova, D.; Ivanova, I.

    2016-10-01

    Antimicrobial effect of TiO2 doped with Ag and Cu on Gram-negative bacteria Escherichia coli and Pseudomonas putida is studied. The thin films are deposited on glass substrates without heating during the deposition by r.f. magnetron co-sputtering of TiO2 target and pieces of Ag and Cu. The studied films, thickness about 65 nm, were as deposited and annealed (5200C, 4h, N2+5%H2, 4Pa). The as deposited thin films TiO2:Ag:Cu have band gap energy of 3.56 eV little higher than the band gap of crystalline anatase TiO2 which can be explained with the quantum effect of the granular structure of r.f. magnetron sputtered films. The annealed samples have band gap of 2.52 eV due to formation of donor levels from Ag and Cu atoms near the bottom of the conduction band. The toxic effect was determined through the classical Koch's method and the optical density measurements at λ=610 nm. The as deposited TiO2:Ag:Cu thin films demonstrate stronger inhibition effect - bactericidal for P. putida and bacteriostatic for E. coli (up to the 6th hour) in comparison with the annealed samples. The both methods of study show the same trends of the bacterial growth independently of their different sensitivity which confirms the observed effect.

  16. Fabrication and enhanced visible light photocatalytic activity of fluorine doped TiO2 by loaded with Ag.

    PubMed

    Lin, Xiaoxia; Rong, Fei; Ji, Xiang; Fu, Degang; Yuan, Chunwei

    2011-11-01

    F-doped TiO2 loaded with Ag (Ag/F-TiO2) was prepared by sol-gel process combined with photoreduction method. The physical and chemical properties of the prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). XPS analysis indicated Ag species existed as Ag0 in the structure of Ag/F-TiO2 samples. UV-Vis diffuse reflectance spectra showed that the light absorption of Ag/F-TiO2 in the visible region had a significant enhancement compared with the F-doped TiO2 (F-TiO2). PL analysis indicated that the electron-hole recombination rate had been effectively inhibited when Ag loaded on the surface of F-TiO2. The photocatalytic activities of the samples were evaluated for the degradation of X-3B (Reactive Brilliant Red dye, C.I. reactive red 2) under visible light (lambda > 420 nm) irradiation. Compared with F-TiO2, the sample of 0.50 Ag/F-TiO2 showed the highest photocatalytic activity. The interaction between F species and metallic Ag was responsible for improving the visible light photocatalytic activity.

  17. The influence of temperature, pressure and Ag doping on the physical properties of TiO2 nanoceramics.

    PubMed

    Tran, V H; Głuchowski, P; Łukowiak, A; Stre Combining Cedilla K, W

    2016-12-01

    Undoped and Ag-doped TiO2 ceramics have been prepared at temperatures between 500-1000 °C and under pressures up to 8 GPa. Their crystal structures and physical properties were investigated by means of EDX, SEM, TEM, X-ray powder diffraction, and magnetization M, specific heat Cp and electrical resistance ρ measurements. It is found that the anatase-structured As-cast powder transforms into rutile and columbite-type at 500 °C and 5.5 GPa. The stabilization of the latter phase is fulfilled under a pressure of 8 GPa and at temperatures above 800 °C. On the basis of experimental results, we conclude that the physical properties of TiO2 can be tailored along with its crystal structure. In particular, magnetic properties change from paramagnetic in anatase and rutile to magnetic correlations and in all likelihood magnetic-field-induced antiferromagnetic short-range order in columbite-structured TiO2. Contrasting behaviour in the temperature dependences of specific heat between anatase/rutile and columbite-type TiO2 is obvious. Differently from anatase/rutile, the Cp of columbite-type TiO2 exhibits a low-temperature excess, being interpreted as due to magnetic correlations, or else the prevalence of soft modes. An analysis of ρ(T) for columbite-type TiO2 in the temperature range of 280-400 K reveals the presence of a new trapping state at an energy level of ∼28 meV within the originally forbidden gap. Furthermore, thermal fluctuation-induced tunnelling and hopping conductivities are suggested to govern in a lower temperature range. We recognize that the Ag-doped contents do not alter the crystal structure but considerably enhance magnetic correlations, compared to undoped samples.

  18. 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.

  19. 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.

  20. 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.

  1. Enhancement of the photoelectric performance of dye-sensitized solar cells using Ag-doped TiO2 nanofibers in a TiO2 film as electrode.

    PubMed

    Jin, En Mei; Zhao, Xing Guan; Park, Ju-Young; Gu, Hal-Bon

    2012-02-02

    For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO2 nanofiber [TN] and Ag-doped TiO2 nanofiber [ATN] have been extended to be included in TiO2 films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO2 photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO2 films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced.

  2. Enhancement of the photoelectric performance of dye-sensitized solar cells using Ag-doped TiO2 nanofibers in a TiO2 film as electrode

    PubMed Central

    2012-01-01

    For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO2 nanofiber [TN] and Ag-doped TiO2 nanofiber [ATN] have been extended to be included in TiO2 films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO2 photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO2 films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced. PMID:22297128

  3. 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

    2014-03-07

    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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

    2015-10-05

    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.

  10. 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.

  11. Necrosis of Staphylococcus aureus by the Electrospun Fe- and Ag-Doped TiO2 Nanofibers

    PubMed Central

    Aboelzahab, Asem; Azad, Abdul-Majeed; Goel, Vijay

    2012-01-01

    Postsurgery infections cause prolonged hospitalization, incurring increased patient and hospital costs, making it increasingly vital to develop an effective solution for the mitigation and elimination of infection buildup at these sites. Incorporation of a bactericidal device at the infection-prone sites provides the capability of attacking bacterial growth even after the patient has left the hospital. Polycrystalline titanium dioxide (TiO2) is photoactive and possesses antibacterial properties that can mitigate the onset of these infections and aid in wound healing. In this work, TiO2 nanofibers were synthesized by electrospinning. Doping with iron as well as with silver (5 wt% and 1 wt%, resp.) was also carried out to increase their effectiveness towards bactericidal properties. The electrospun fibers were processed and tested in the presence of light in the suspensions of methicillin-susceptible Staphylococcus aureus (MSSA) bacteria, which are the leading infection-inducing bacteria among hospital patients. It was found that upon brief activation (cf. 30 s) by an infrared laser source, greater than 90% of the S. aureus was rendered inactive within cf. 10 min. of exposure, thereby showing the potential of titania nanofibers for effective mitigation of infection. PMID:24977085

  12. 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.

  13. Structural analysis of TiO2 and TiO2-Ag thin films and their antibacterial behaviors

    NASA Astrophysics Data System (ADS)

    Hsieh, J. H.; Yu, R. B.; Chang, Y. K.; Li, C.

    2012-01-01

    TiO2 (rutile and anatase) thin films was first prepared using reactive sputtering, in an Ar+O2 plasma. In the 2nd stage of the experiment, various amounts (3, 7, and 10 at. %) of Ag was doped into the rutile film in order to form TiO2-Ag thin films. These films were annealed for one hour in Ar atmosphere, at 300, 400, and 500 °C. The films' structures were then examined using X-ray diffractometry. FESEM (field-emission scaning electron microscopy) was used to investigate the surface emergence of Ag particles. As for the examination of optical band gaps and absorption of these films, UV-Vis-NIR photometer was used. The results show that, in as-deposited condition, the addition of Ag might disrupt the growth of crystalline structure and cause the formation of amorphous films. After annealing, it is found that the structure tends to become anatase phase which is a metastable phase between amorphous titanium oxide and rutile. More importantly, the absorption of the Ag-doped films would be enhanced in the visible-light range. Some of the enhancement is clearly due to plasmon resonance effect. The Ag-doped samples have shown some antibacterial effect in dark. When irradiated with light, the samples show a synergistic behavior combining the bactericidal effect of Ag ions and photocatalytic effect of TiO2.

  14. 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.

  15. 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.

  16. Influence of silver doping on surface defect characteristics of TiO2

    NASA Astrophysics Data System (ADS)

    Tripathi, S. K.; Rani, Mamta

    2015-08-01

    In the present work, we proposed a novel silver doped TiO2 polyethylene conjugated films to improve the performance of DSSCs. Oxides nanoparticles dispersed in a semiconducting polymer form the active layer of a solar cell. Localized surface plasmon resonance effects associated with spatially dispersed silver (Ag) nanoparticles can be exploited to enhance the light-harvesting efficiency, the photocurrent density and the overall light-to electrical-energy-conversion efficiency of high-area DSSCs based TiO2 photoanodes. Silver doped titanium dioxide (TiO2:Ag) is prepared by sol-gel technique and deposited on fluorine doped indium oxide (FTO) coated glass substrates by using doctor blade technique at 550°C from aqueous solutions of titanium butoxide and silver nitrate precursors. The effect of Ag doping on electrical properties of films is studied. The Ag-TiO2 films are about 548 times more photosensitive as compare to the pure TiO2 sample. The presence of metallic Ag nanoparticles and oxygen vacancy on the surface of TiO2 nanoparticles promotes the separation of photogenerated electron-hole pairs and thus enhances the photosensitivity. Photoconduction mechanism of all prepared samples is investigated by performing transient photoconductivity measurements on TiO2 and Ag-TiO2 films keeping intensity of light constant.

  17. Silver nanoparticle doped TiO2 nanofiber dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Jinwei; Chen, Xi; Ai, Nan; Hao, Jumin; Chen, Qi; Strauf, Stefan; Shi, Yong

    2011-09-01

    Silver nanoparticle doped TiO2 nanofibers, prepared by the electrospinning process were used as the photoanode to fabricate dye sensitized solar cells. It was found that the nanoparticle doped solar cells have a significantly increased photocurrent density resulting in a 25% improved conversion efficiency compared to undoped solar cells. The improved performance is attributed to two factors: (1) the increased light harvesting efficiency due to the plasmon enhanced optical absorption induced by Ag nanoparticles, and (2) the improved electron collection efficiency as a result of faster electron transport in the Ag doped TiO2 nanofiber photoanode.

  18. The effect of Fe segregation on the photocatalytic growth of Ag nanoparticles on rutile TiO2(001)

    NASA Astrophysics Data System (ADS)

    Busiakiewicz, Adam; Kisielewska, Aneta; Piwoński, Ireneusz; Batory, Damian

    2017-04-01

    The photocatalytic growth of silver nanoparticles (AgNPs) on rutile TiO2(001) and Fe-modified rutile TiO2(001) monocrystals was investigated. Various amount of Fe was segregated in a controlled way from the doped TiO2 substrates in ultra-high vacuum conditions resulting in low- medium- and high- content of Fe on TiO2 substrates. AgNPs were grown on pristine TiO2 and substrates containing Fe by photoreduction of Ag+ ions under UV illumination. It was found that the size of AgNPs was larger on Fe/TiO2 than on TiO2 while the surface density exhibited the opposite behavior - a large number of AgNPs were present on the TiO2 surface but only a few AgNPs were visible on the Fe/TiO2 substrates. The reason for the differences in size and number of AgNPs on TiO2 and Fe/TiO2 is the limited access of Ag+ to the TiO2 surface caused by the large number of Fe grains segregated onto the TiO2 surface. Another possible reason for the various AgNPs morphologies is alteration in the mechanism of Ag+ photoreduction caused by iron present as Fe3+ ions and by newly formed AgNPs playing the role of electron traps. The surface elemental analysis of the investigated materials was performed with the use of X-ray photoelectron spectroscopy (XPS) and confirmed the composition of AgNPs/Fe/TiO2 systems. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed sizes, morphology and distribution of the nanostructures.

  19. 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

    2015-10-05

    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.

  20. TiO2 nanoparticles co-doped with silver and nitrogen for antibacterial application.

    PubMed

    Yuan, Yali; Ding, Jianqiang; Xu, Jinsheng; Deng, Jian; Guo, Jianbo

    2010-08-01

    We have prepared a series of TiO2 nanoparticles for antibacterial applications. These TiO2 nanoparticles were prepared by the hydrolysis precipitation method with Ti(OBu)4, silver nitrate and ammonia. Crystal structure, particle size, interfacial structure and UV-visible light response of the prepared nanoparticles were characterized by X-ray diffraction measurements (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRs). The XRD spectra showed that all samples were anatase structure calcined at 450 degrees C for 3 hours. The Ag doping made the peak of diffraction wider. The results of TEM showed that the nanoparticles of TiO2, N-TiO2 and 1% Ag-N-TiO2 were all spherical in shape and well distributed with a mean size of 19.8 nm, 39.2 nm and 20.7 nm, respectively. N doping caused the nanoparticle size to increase, while, when the doped amount of Ag+ increased, the TiO2 particle size decreased. The FTIR revealed that Ag and N doping of TiO2 appeared to have strong absorption by -OH group and showed the characteristic absorption band of NH4+ and Ag. The UV-Vis-DRs indicated that the absorption band of Ag-N co-doped TiO2 had red shift and that the optical absorption response (between 400 nm and 700 nm) had obvious enhancement. The antibacterial properties of nanoparticles were investigated by agar diffusion method toward Escherichia coli and Bacillus subtilis. The results indicated that both Ag- and N-doped TiO2 could increase the antibacterial properties of TiO2 nanoparticles under fluorescent light irradiation. A 1% Ag-N-TiO2 had the highest antibacterial activity with a clear antibacterial circle of 33.0 mm toward Escherichia coli and 22.8 mm toward Bacillus subtilis after cultivation for 24 hours.

  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. Design of Ag-Modified TiO2-Based Films with Controlled Optical and Photocatalytic Properties

    NASA Astrophysics Data System (ADS)

    Smirnova, N. P.; Manuilov, E. V.; Korduban, O. M.; Gnatyuk, Yu. I.; Kandyba, V. O.; Eremenko, A. M.; Gorbyk, P. P.; Shpak, A. P.

    TiO2-based functional coatings doped with Ag nanoparticles were prepared via template assisted sol-gel method with an attempt to enhance the decomposition reaction rate of industrial water pollutants. The films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron (XPS), and UV-vis spectroscopies. Catalytic activity in photooxidative organic dyes decomposition remarkably enhances TiO2/ZnO samples with homogeneously distributed noble metal nanoparticles. Ag nanoparticles in TiO2 matrix improve an efficiency of charge separation and charge-transfer processes, acting as traps for photoinduced electrons.

  5. Synergistic effect of interfacial lattice Ag(+) and Ag(0) clusters in enhancing the photocatalytic performance of TiO2.

    PubMed

    Xu, Liming; Zhang, Dandan; Ming, Lufei; Jiao, Yanchao; Chen, Feng

    2014-09-28

    An interfacial lattice Ag(+) doped on TiO2 (Ag(+)/TiO2) was prepared by eluting Ag(0) clusters from a hydrothermally prepared Ag(0)/Ag(+)/TiO2 composite. An Ag(+)/TiO2@Ag(0) composite photocatalyst was subsequently obtained via a secondary Ag(0) clusters loading process to the Ag(+)/TiO2. The photocatalytic activity of Ag(+)/TiO2@Ag(0) was greatly improved compared to Ag(0)/Ag(+)/TiO2 and Ag(+)/TiO2. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) testing verified that Ag(+) ions occur as an interfacial lattice Ag(+) species in the composites. The enhancement effect of the interfacial lattice Ag(+) species is exhibited by the newly-formed Ag(+)/TiO2@Ag(0) as the interfacial lattice Ag(+) is fully exposed but not overlapped with the re-loaded Ag(0) clusters. The interfacial lattice Ag(+) ions and Ag(0) clusters are both responsible for the photocatalytic performance improvement of the catalyst, in either the photocatalytic degradation of methyl orange or photocurrent measurement.

  6. 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

  7. Doping of TiO2 for sensitized solar cells.

    PubMed

    Roose, Bart; Pathak, Sandeep; Steiner, Ullrich

    2015-11-21

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

  8. Ag/WO3-codoped TiO2 nanoparticles: relation between structure, sorption, and photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Xu, Jing Y.; Wen, Chen; Jia, Li M.; Xiao, Chang F.

    2009-07-01

    Nanostructured Ag/WO3-TiO2 particles responding to sunlight were synthesized by dissolving silver nitrate, sodium tungstate and tetrabutyl titanate precursors in a suitable solvent. The obtained powders were characterized by a series of analytical methods including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, Zeta potential measurements and UV-vis diffuse reflectance spectra (UV-vis DRS) to demonstrate their physicochemical properties. The as-prepared Ag/WO3-TiO2 samples were evaluated for their photocatalytic activity towards the degradation of methylene blue (MB) under sunlight irradiations. Both silver (Ag) and tungsten (W) species were well dispersed over TiO2 surface with less than 6.0 mol % Ag and 3.0 mol % W to Ti element and contributed to a formation of crystalline WO3. XRD analysis particularly demonstrates the existence of mixed-phase TiO2 materials, to which the improvement in photocatalytic activity is attributed. Besides, the light absorption of doped samples is prominent red shifted relative to the pure TiO2 due to the synergetic effect among the components of Ag, WO3 and TiO2 in the codoped-TiO2. The particle size of the Ag/WO3-TiO2 powders was found to be a decrease which is accompanied with the increase of the surface area. The excellent stability and dispersity of the Ag/WO3-TiO2 powders in aqueous solution could be attributed to the enhanced Zeta potential. On the other hand, the adsorption performances of different samples were tested in the removal of two dyes from aqueous solution(congo red and methylene blue). The first-order adsorption equilibrium constants were determined and the results obtained were fitted by Langmuir monolayer formation. Thus, the Langmuir adsorption isotherm parameters were estimated from the experimental data.

  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. Photocatalytic hydrogen generation over lanthanum doped TiO2 under UV light irradiation.

    PubMed

    Liu, Y; Xie, L; Li, Y; Qu, J L; Zheng, J; Li, X G

    2009-02-01

    TiO2 nanoparticles doped with different amount of lanthanum were obtained by sol-gel approach and followed annealing at different temperature. The crystal size of TiO2 doped with lanthanum was smaller than that of pure TiO2. Photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 was investigated. The photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 is higher than that of pure TiO2. It was found that the optimal photocatalyst was TiO2 doped with 2 wt% lanthanum and calcined at 600 degrees C for 4 h which had hydrogen generation rate 700.6 micromol h(-1).

  11. Preparation and properties of antibacterial TiO2@C/Ag core-shell composite

    NASA Astrophysics Data System (ADS)

    Tan, San-Xiang; Tan, Shao-Zao; Chen, Jing-Xing; Liu, Ying-Liang; Yuan, Ding-Sheng

    2009-08-01

    An environment-friendly hydrothermal method was used to prepare TiO2@C core-shell composite using TiO2 as core and sucrose as carbon source. TiO2@C served as a support for the immobilization of Ag by impregnation in silver nitrate aqueous solution. The chemical structures and morphologies of TiO2@C and TiO2@C/Ag composite were characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The antibacterial properties of the TiO2@C/Ag core-shell composite against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the viable cell counting method. The results indicate that silver supported on the surface of TiO2@C shows excellent antibacterial activity.

  12. Preparation, characterization and visible light photocatalytic activity of silver, nitrogen co-doped TiO2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Khan, Matiullah; Ramin Gul, Sahar; Li, Jing; Cao, Wenbin; Mamalis, Athanasios G.

    2015-06-01

    TiO2 photocatalyst codoped with Silver (Ag) and Nitrogen (N) with different Ag doping concentrations is successfully synthesized by hydrothermal method. The as-synthesized samples are characterized through x-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-vis. absorption spectra and x-ray photoelectron spectroscopy (XPS). The photocatalytic response is evaluated by the photodegradation of methylene blue under visible light irradiations. All synthesized samples are composed of pure anatase phase with good crystallinity. The absorption edge of codoped TiO2 is shifted towards visible light region. X-ray photoelectron spectroscopy confirmed the existence of silver and nitrogen in the codoped samples. All the codoped samples demonstrated improved photocatalytic activity compared to pure TiO2. Among the different codoped samples, the one with silver doping concentration of 4 at. % exhibited the highest photoactivity.

  13. Anatase TiO2 sheet-assisted synthesis of Ti(3+) self-doped mixed phase TiO2 sheet with superior visible-light photocatalytic performance: Roles of anatase TiO2 sheet.

    PubMed

    Zhang, Xiaojie; Zuo, Guoqing; Lu, Xin; Tang, Changqing; Cao, Shuo; Yu, Miao

    2017-03-15

    On the basis of measurements, such as field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, X-ray diffraction, electron paramagnetic resonance, photoluminescence spectra, and photocurrent measurements, the roles of anatase TiO2 sheet on synthesizing Ti(3+) self-doped mixed phase TiO2 nanosheets (doped TiO2 (A/R, TiO2 (A))) and on improving the performance for photocatalytic CO2 reduction were explored systematically. High surface area anatase TiO2 nanosheets (TiO2 (A)) as a substrate, structure directing agent, and inhibitor, mediated the synthesis of Ti(3+) self-doped mixed phase TiO2 nanosheets. Addition of TiO2 (A) significantly improved not only visible light absorption of doped TiO2 (A/R, TiO2 (A)), but also the efficiency of photo-excited charges separations due to the existence of interfacial regions of anatase-rutile TiO2 junctions. Finally, a possible mechanism for interfacial charge transfer at the anatase-rutile TiO2 interface and for photocatalytic CO2 reduction over Pt loaded doped TiO2 (A/R, TiO2 (A)) were proposed.

  14. 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.

  15. Photodegradation of nalidixic acid assisted by TiO(2) nanorods/Ag nanoparticles based catalyst.

    PubMed

    Petronella, F; Diomede, S; Fanizza, E; Mascolo, G; Sibillano, T; Agostiano, A; Curri, M L; Comparelli, R

    2013-05-01

    Two different nanosized TiO2-based catalysts supported onto glass with tailored photocatalytic properties upon irradiation by UV light were successfully employed for the degradation of nalidixid acid, a widely diffused antibacterial agent of environmental relevance known to be non-biodegradable. Anatase rod-like TiO2 nanocrystals (TiO2NRs) and a semiconductor oxide-noble metal nanocomposite TiO2 NRs/Ag nanoparticles (NPs), synthesized by colloidal chemistry routes, were cast onto glass slide and employed as photocatalysts. A commercially available catalyst (TiO2 P25), also immobilized onto a glass slide, was used as a reference material. It was found that both TiO2 NRs/Ag NPs composite and TiO2 NRs demonstrated a photocatalytic efficiency significantly higher than the reference TiO2 P25. Specifically, TiO2 NRs/Ag NPs showed a photoactivity in nalidixic acid degradation 14 times higher than TiO2 P25 and 4 times higher than bare TiO2 NRs in the first 60min of reaction. Several by-products were identified by HPLC-MS along the nalidixic acid degradation, thus getting useful insight on the degradation pathway. All the identified by-products resulted completely removed after 6h of reaction.

  16. 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

  17. AC conductivity studies of Fe doped TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Vijayan, P. P.; Thomas, M.; George, K. C.

    2015-02-01

    Fe-doped TiO2 nanotubes are prepared by the combination of sol-gel process with hydrothermal treatment. The morphology and crystalline structure of TiO2 nanotubes are characterized by transmission electron microscopy (TEM), X-ray diffraction respectively (XRD). Fe doping induces a structural transformation from anatase to rutile. The temperature dependence of the ac electrical conductivity is investigated in the temperature range 303-413 K. Positive temperature coefficient of resistance is observed in the Fe doped TiO2 nanotubes. PL spectrum shows the presence of oxygen vacancies and self trapped excitons in Fe doped TiO2 nanotubes and undoped samples.

  18. Photocatalytic degradation properties of V-doped TiO2 to automobile exhaust.

    PubMed

    Wang, Tong; Shen, Dongya; Xu, Tao; Jiang, Ruiling

    2017-05-15

    To improve the photocatalytic degradation properties of titanium dioxide (TiO2) used as raw materials for purifying automobile exhaust (AE), the vanadium (V)-doped TiO2 samples were prepared. The photocatalytic degradation efficiencies of V-doped TiO2 to each component in AE were evaluated under ultraviolet (UV) and visible light irradiation, respectively. Results indicated that the photocatalytic activity of V-doped TiO2 to AE was higher than that of pure TiO2, and the optimal V dopant content of TiO2 was 1.0% under UV light irradiation. The degradation efficiencies of V-doped TiO2 to NOx and HC were higher than those to CO2 and CO in AE because of the reversible reaction between CO2 and CO. In addition, it was found that the photocatalytic degradation efficiencies of V-doped TiO2 to each component in AE were also increased under visible light irradiation. The V-doped TiO2 also showed higher degradation efficiencies to NOx and HC than those to CO2 and CO under visible light irradiation. The V doped TiO2 presented higher photocatalytic activity to CO2 than that to CO, but the reversible reaction between CO and CO2 was not found under visible light irradiation. The photocatalytic reactions of pure and V-doped TiO2 samples to each component in AE followed the first order kinetic pathway under the two light irradiations. It is concluded that the V doping is a feasible method to improve the photocatalytic degradation properties of TiO2 to AE for air purification, developing a sustainable environmental purification technology based on TiO2 materials.

  19. 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.

  20. Synthesis of Ag ion-implanted TiO2 thin films for antibacterial application and photocatalytic performance.

    PubMed

    Hou, Xinggang; Ma, Huiyan; Liu, Feng; Deng, Jianhua; Ai, Yukai; Zhao, Xinlei; Mao, Dong; Li, Dejun; Liao, Bin

    2015-12-15

    TiO2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag(3+)) ions were doped into the crystalline lattice of TiO2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment.

  1. Photocatalytic antibacterial performance of Sn(4+)-doped TiO(2) thin films on glass substrate.

    PubMed

    Sayilkan, Funda; Asiltürk, Meltem; Kiraz, Nadir; Burunkaya, Esin; Arpaç, Ertuğrul; Sayilkan, Hikmet

    2009-03-15

    Pure anatase, nanosized and Sn(4+) ion doped titanium dioxide (TiO(2)) particulates (TiO(2)-Sn(4+)) were synthesized by hydrothermal process. TiO(2)-Sn(4+) was used to coat glass surfaces to investigate the photocatalytic antibacterial effect of Sn(4+) doping to TiO(2) against gram negative Escherichia coli (E. coli) and gram positive Staphylococcus aureus (S. aureus). Relationship between solid ratio of TiO(2)-Sn(4+) in coatings and antibacterial activity was reported. The particulates and the films were characterized using particle size analyzer, zeta potential analyzer, Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), SEM, AAS and UV/VIS/NIR techniques. The results showed that TiO(2)-Sn(4+) is fully anatase crystalline form and easily dispersed in water. Increasing the solid ratio of TiO(2)-Sn(4+) from 10 to 50% in the coating solution increased antibacterial effect.

  2. Photocatalytic degradation of chloramphenicol in an aqueous suspension of silver-doped TiO2 nanoparticles.

    PubMed

    Shokri, Mohammad; Jodat, Akbar; Modirshahla, Nasser; Behnajady, Mohammad A

    2013-01-01

    In this work, silver-doped TiO2 (Ag/TiO2) nanoparticles were synthesized using a photodeposition technique. The prepared Ag/TiO2 nanoparticles were characterized using TEM, SEM, XRD, and EDX techniques. The characterization of Ag/TiO2 nanoparticles using SEM and EDX techniques revealed the dispersion of Ag metal on the surface of TiO2. The photocatalytic activity of Ag/TiO2 and bare TiO2 in the presence of ultraviolet irradiation was investigated in the removal of chloramphenicol (CAP) as an antibiotic. CAP is a broad-spectrum antibiotic exhibiting activity against both Gram-positive and Gram-negative bacteria, as well as other groups of microorganisms. However, it is, in certain susceptible individuals, associated with serious toxic effects in humans including bone marrow depression, particularly severe in the form of fatal aplastic anaemia. The effects of the operational factors, such as doping content of Ag, photocatalyst dosage and calcination temperature were evaluated in the catalytic activity of Ag/TiO2. The results showed that the photocatalytic efficiency of TiO2 nanoparticles for the degradation of CAP, can be significantly improved by deposition an optimum amount of Ag nanoparticles (0.96 wt%) in the calcination temperature 300 degrees C. It was found that 900 mg/L of Ag/TiO2 is the optimum dosage in the removal of CAP with 20 mg/L initial concentration. The highest removal efficiency of CAP (-100%) at the optimum conditions was observed in 20 min. A mineralization study under optimum conditions showed about 88% reduction in total organic carbon after 120 min of irradiation time.

  3. 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.

  4. Synthesis of natural cellulose-templated TiO2/Ag nanosponge composites and photocatalytic properties.

    PubMed

    Yu, Dong-Hui; Yu, Xiaodan; Wang, Changhua; Liu, Xian-Chun; Xing, Yan

    2012-05-01

    In this paper, TiO(2)/Ag sponge-like nanostructure composites have been prepared by the surface sol-gel method with the template of natural cellulose, which is relatively simple, low-cost, and environmentally friendly. The Ag nanoparticles are deposited on the TiO(2) nanosponges through UV irradiation photoreduction of silver nitrate solutions. The physicochemical properties of as-prepared composites are characterized by XRD, BET, SEM, TEM, XPS and UV-vis DRS techniques. The UV-light photocatalytic activities of the composites are evaluated through the photodegradation of two model organic molecules including RhB and salicylic acid. The experimental results show that the photocatalytic activities of TiO(2)/Ag nanosponge composites are superior to that of P25, pure TiO(2) nanoparticle aggregates synthesized by the hydrothermal method and pure TiO(2) nanosponge. The superior activities of TiO(2)/Ag nanosponge composite photocatalysts can be attributed to the unique nanosponge morphology, uniform dispersion of Ag nanoparticles, and strong interaction between Ag and TiO(2) nanosponges.

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

    PubMed

    Lin, Yu-Chih; Lee, Ho-Shan

    2010-07-15

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

  6. Antibacterial and Photodegradative Properties of Metal Doped TiO2 thin Films Under Visible Light.

    PubMed

    Ogorevc, Jerneja Šauta; Tratar-Pirc, Elizabeta; Matoh, Lev; Peter, Bukovec

    2012-06-01

    Doped (Au, Ag) and undoped TiO2 thin films were prepared on soda-lime glass via the sol-gel method by dip-coating from TiCl4 precursor, followed by 30 minutes calcination at 500 °C to obtain transparent thin films with good adhesion to the substrate. XRD analysis showed that the particle size of samples heat treated at 500 °C was ~10 nm for all of the samples prepared, both doped and undoped ones. SEM images revealed that the thin film surface was homogeneous and nano-porous. The hydrophilicity of the thin films was estimated by contact angle measurements. The photodegradation rate of an aqueous solution of the azo dye Plasmocorinth B on the thin films was tested by in-situ UV-Vis spectroscopic measurements of the dye solution. The best photocatalytic activity under visible and UVA light was exhibited by undoped TiO2 thin films, whereas Au doped thin films were slightly less active. On the other hand, the best antimicrobial activity toward the E. coli strain DH5a under visible light was displayed by the Au/TiO2 thin films.

  7. 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

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

    PubMed

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-03-20

    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.

  9. 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.

  10. Structural and photocatalytic studies of Mn doped TiO2 nanoparticles.

    PubMed

    Chauhan, Ruby; Kumar, Ashavani; Chaudhary, Ram Pal

    2012-12-01

    Mn-doped TiO(2) nanoparticles (Ti(1-)(x)Mn(x)O(2); where x=0.00-0.10) were synthesized by sol-gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV-Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and measurements show that the size of crystallites is in the range of 10-20 nm. Optical measurements indicated a red shift in the absorption band edge after Mn doping. Direct allowed band gap of undoped and Mn-doped TiO(2) nanoparticles measured by UV-Vis spectrometer were 3.00 and 2.95 eV at 300 °C, respectively. Photocatalytic activities of TiO(2) and Mn doped TiO(2) were evaluated by irradiating the sample solution of methylene blue (MB) dye under ultraviolet and visible light exposure. It was found that Mn-doped TiO(2) bleaches MB much faster than undoped TiO(2) upon its exposure to the visible light as comparison to ultraviolet light. The experiment demonstrated that the photodegradation efficiency of Mn-doped TiO(2) was significantly higher than that of undoped TiO(2) upon its exposure to visible light.

  11. 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.

  12. Photocatalytic treatment of municipal wastewater using modified neodymium doped TiO(2) hybrid nanoparticles.

    PubMed

    Shahmoradi, Behzad; Ibrahim, Ibrahim A; Sakamoto, Naonori; Ananda, Sannaiah; Somashekar, Rudrappa; Row, Tagur N Guru; Byrappa, Kullaiah

    2010-08-01

    Photocatalytic degradation of municipal wastewater was investigated using reagent grade TiO(2) and modified neodymium doped TiO(2) hybrid nanoparticles. For the first time, surface modification of Nd(3 +) doped TiO(2) hybrid nanoparticles were carried out with n-butylamine as surface modifier under mild hydrothermal conditions. The modified nanoparticles obtained were characterized by Powder XRD, FTIR, DLS, TEM, BET surface area, zeta potential and UV-Vis Spectroscopy. The characterization results indicated better morphology, particle size distribution and low agglomeration of the nanoparticles synthesized. It was found that photodegradation of wastewater using surface modified neodymium doped TiO(2) nanoparticles was more compared to pure TiO(2), which can be attributed to the doping and modification with n-butylamine.

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

    PubMed

    Sirisaksoontorn, Weekit; Thachepan, Surachai; Songsasen, Apisit

    2009-07-15

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

  14. Photocatalytic degradation of phenol by visible light-responsive iron-doped TiO2 and spontaneous sedimentation of the TiO2 particles.

    PubMed

    Nahar, Mst Shamsun; Hasegawa, Kiyoshi; Kagaya, Shigehiro

    2006-12-01

    Fe-doped TiO2 was prepared by the calcination of Fe(x)TiS(2) (x=0, 0.002, 0.005, 0.008, 0.01) and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible diffuse reflectance spectra. All the Fe-doped TiO2 were composed of an anatase crystal form and showed red shifts to a longer wavelength. The activity of the Fe-doped TiO2 for the degradation of phenol was investigated by varying the iron content during UV (365nm) and visible light (405nm and 436nm) irradiation. The degradation rate depended on the Fe content and the Fe-doped TiO2 was responsive to the visible light as well as the elevated activity toward UV light. The molar ratio of 0.005 was the optimum for both the UV and visible light irradiations. The result was discussed on the basis of the balance of the excited electron-hole trap by the doped Fe(3+) and their charge recombination on the doped Fe(3+) level. The Fe-doped TiO2 (x=0.005) was more active than P25 TiO2 under solar light irradiation. The suspended Fe-doped TiO2 spontaneously precipitated once the stirring of the reaction mixture was terminated.

  15. 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.

  16. Controlled preparation of porous TiO2-Ag nanostructures through supramolecular assembly for plasmon-enhanced photocatalysis.

    PubMed

    Fei, Jinbo; Li, Junbai

    2015-01-14

    By templating Ag(+)-induced supramolecular assembly at different temperatures, porous TiO2-Ag nanotubes and nanospheres are fabricated in a controlled manner due to the effect of Rayleigh instability. Compared with traditional TiO2 nanoparticles, TiO2-Ag nanostructures above show much more extensive visible light absorption and exhibit the noticeably plasmon-enhanced photocatalysis because of the existence of Ag nanoparticles.

  17. Both enhanced biocompatibility and antibacterial activity in Ag-decorated TiO2 nanotubes.

    PubMed

    Lan, Ming-Ying; Liu, Chia-Pei; Huang, Her-Hsiung; Lee, Sheng-Wei

    2013-01-01

    In this study, Ag is electron-beam evaporated to modify the topography of anodic TiO2 nanotubes of different diameters to obtain an implant with enhanced antibacterial activity and biocompatibility. We found that highly hydrophilic as-grown TiO2 nanotubes became poorly hydrophilic with Ag incorporation; however they could effectively recover their wettability to some extent under ultraviolet light irradiation. The results obtained from antibacterial tests suggested that the Ag-decorated TiO2 nanotubes could greatly inhibit the growth of Staphylococcus aureus. In vitro biocompatibility evaluation indicated that fibroblast cells exhibited an obvious diameter-dependent behavior on both as-grown and Ag-decorated TiO2 nanotubes. Most importantly, of all samples, the smallest diameter (25-nm-diameter) Ag-decorated nanotubes exhibited the most obvious biological activity in promoting adhesion and proliferation of human fibroblasts, and this activity could be attributed to the highly irregular topography on a nanometric scale of the Ag-decorated nanotube surface. These experimental results demonstrate that by properly controlling the structural parameters of Ag-decorated TiO2 nanotubes, an implant surface can be produced that enhances biocompatibility and simultaneously boosts antibacterial activity.

  18. Inverted organic solar cells based on Cd-doped TiO2 as an electron extraction layer

    NASA Astrophysics Data System (ADS)

    Ranjitha, A.; Muthukumarasamy, N.; Thambidurai, M.; Velauthapillai, Dhayalan; Madhan Kumar, A.; Gasem, Zuhair M.

    2014-10-01

    Nanocrystalline Cd-doped TiO2 thin films have been prepared by sol-gel method. X-ray diffraction analysis reveals that TiO2 and Cd-doped TiO2 nanocrystalline thin films are of anatase phase. The average grain size of TiO2 and Cd-doped TiO2 nanocrystalline thin films was found to lie in the range of 15-18 nm. Solar cells have been fabricated with a device structure of ITO/Cd-doped TiO2/P3HT:PC71BM/MoO3/Al configuration. The power conversion efficiency of the inverted organic solar cell with Cd-doped TiO2 is 3.06% and is higher than that of TiO2 based organic solar cell (2.64%).

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

    PubMed

    Umadevi, M; Parimaladevi, R; Sangari, M

    2014-01-01

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

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

    PubMed

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

    2015-06-05

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

  1. 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

  2. Effect of band gap engineering in anionic-doped TiO2 photocatalyst

    NASA Astrophysics Data System (ADS)

    Samsudin, Emy Marlina; Abd Hamid, Sharifah Bee

    2017-01-01

    A simple yet promising strategy to modify TiO2 band gap was achieved via dopants incorporation which influences the photo-responsiveness of the photocatalyst. The mesoporous TiO2 was successfully mono-doped and co-doped with nitrogen and fluorine dopants. The results indicate that band gap engineering does not necessarily requires oxygen substitution with nitrogen or/and fluorine, but from the formation of additional mid band and Ti3+ impurities states. The formation of oxygen vacancies as a result of modified color centres and Ti3+ ions facilitates solar light absorption and influences the transfer, migration and trapping of the photo-excited charge carriers. The synergy of dopants in co-doped TiO2 shows better optical properties relative to single N and F doped TiO2 with c.a 0.95 eV band gap reduction. Evidenced from XPS, the synergy between N and F in the co-doped TiO2 uplifts the valence band towards the conduction band. However, the photoluminescence data reveals poorer electrons and holes separation as compared to F-doped TiO2. This observation suggests that efficient solar light harvesting was achievable via N and F co-doping, but excessive defects could act as charge carriers trapping sites.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  5. Effect of fluorine doped TiO2 on the property of perovskite solar cell

    NASA Astrophysics Data System (ADS)

    Zhang, X. Q.; Wu, Y. P.; Huang, Y.; Zhou, Z. H.; Shen, S.

    2017-03-01

    Anatase TiO2 nanoparticles with different amounts of fluorine doping were synthesized by a hydrothermal method using hydrogen titanate nanotubes as a precursor and applied as mesoporous layer for preparing perovskite solar cell. The morphology and structures were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), meanwhile, the properties and performances were tested by photoluminescence spectrum (PL) and current density and voltage (J-V) curve. It was found that doping fluorine into TiO2 made the photoelectric conversion efficiency (PCE) of perovskite solar cell (PSC) to be improved. The best PCE of PSC based on a F-doped TiO2 was 13.06% and increased by 51% compared to an un-doped TiO2. The study provided a direction for the exploration of high performance electron transport layer of perovskite solar cell.

  6. Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light.

    PubMed

    Sahoo, Chittaranjan; Gupta, Ashok K

    2015-01-01

    Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

  7. Synergistic effects of F and Fe in co-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Yufei; Shen, Huiyuan; Liu, Yanhua

    2016-03-01

    TiO2 photocatalysts co-doped with F and Fe were synthesized by a sol-gel method. Synergistic effects of F and Fe in the co-doped TiO2 were verified by NH3 decomposition, X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV-Vis) absorption spectroscopy, and was analyzed by the simulation based on the density functional theory (DFT). The results from NH3 decomposition confirmed that the cooperation of F and Fe broadened the optical response of TiO2 to visible light region and also enhanced the photocatalytic activity of TiO2 under ultraviolet light. XRD patterns, SEM and HRTEM images showed that the co-doped samples were nanometric anatase with an average particle size of 25 nm. Co-doping with F and Fe inhibited the grain growth of TiO2 from anatase to rutile and resulted in a larger lattice defect. XPS analysis exhibited that the doped F and Fe atoms were into the TiO2 lattice. UV-Vis absorption spectra showed that its optical absorption edge was moved up to approximately 617 nm and its ultraviolet absorption was also enhanced. The DFT results indicated that the cooperation of Fe 3d and O 2p orbits narrowed the band gap of TiO2 and F 2p orbit widened the upper valence bands. The synergistic electron density around F and Fe in co-doped TiO2 was capable to enhance the photo-chemical stability of TiO2.

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

    DOE PAGES

    Nie, Xiliang; Zhuo, Shuping; Maeng, Gloria; ...

    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

  9. Wavelength-switchable photocurrent in a hybrid TiO2-Ag nanocluster photoelectrode.

    PubMed

    Chen, Hongjun; Wang, Qiong; Lyu, Miaoqiang; Zhang, Zhi; Wang, Lianzhou

    2015-08-04

    A hybrid TiO2-Ag nanocluster (NC) photoelectrode demonstrates unique wavelength-switchable photocurrent. By simply tuning the light wavelength from ultraviolet (UV) to visible light, the photocurrent generated on a single electrode can be switched from anodic to cathodic current, in which the Ag NCs behave like a new type of visible light active photocatalyst.

  10. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation

    NASA Astrophysics Data System (ADS)

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-02-01

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the “dipping and drying” process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning.

  11. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation.

    PubMed

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-02-20

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the "dipping and drying" process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning.

  12. Super-hydrophobic Silver-Doped TiO2 @ Polycarbonate Coatings Created on Various Material Substrates with Visible-Light Photocatalysis for Self-Cleaning Contaminant Degradation

    PubMed Central

    Li, Zhengjian; Sun, Zongzhao; Duan, Zhiqiang; Li, Rui; Yang, Yanli; Wang, Jingyi; Lv, Xiaoxia; Qi, Wei; Wang, Hua

    2017-01-01

    In the present work, a facile and efficient fabrication method has been developed for creating super-hydrophobic coatings of silver-doped TiO2@polycarbonate (TiO2 (Ag)@PC) on the substrates of different materials with photocatalytic self-cleaning performances simply by the “dipping and drying” process. The substrates were first patterned with glue and then deposited with the dopamine-capped TiO2 (Ag)@PC (DA-TiO2 (Ag)@PC) nanocomposites, followed by the further etching with dimethylbenzene. The so prepared super-hydrophobic E-DA-TiO2(Ag)@PC coatings could present the lotus leaf-like porous architectures, high adhesion stability, and especially the visible-light photocatalysis for organic contaminant degradation, thus promising the wide outdoor and indoor applications like water proofing, metal erosion protection, and surface self-cleaning. PMID:28218285

  13. Antibacterial effect of visible light reactive TiO2/Ag nanocomposite thin film on the orthodontic appliances.

    PubMed

    Yun, Kwidug; Oh, Gyejeong; Vang, Mongsook; Yang, Hongso; Lim, Hyunpil; Koh, Jeongtae; Jeong, Woonjo; Yoon, Dongjoo; Lee, Kyungku; Lee, Kwangmin; Park, Sangwon

    2011-08-01

    This study evaluated the antibacterial effect of a visible light reactive TiO2/Ag nanocomposite thin film on dental orthodontic wire (STS 304 wire). The growth of S. mutans and A. actinomycetemcomitans was suppressed on the specimens coated with TiO2/Ag compared to the uncoated specimens. The antibacterial effect of the TiO2/Ag nanocomposite thin film was improved under visible light irradiation.

  14. 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.

  15. Electronic properties of silver and nickel doped TiO2 anatase (100) surface

    NASA Astrophysics Data System (ADS)

    Jensen, Stephanie

    Using computational approaches, one is able to better understand electron transfer and specific atomistic behaviors in semiconductor materials; it is often more cost and time effective than experimental methods. If computed characteristics of a material show promise, experimentalists can synthesize and further examine the structure of such material. In the computational study, TiO2 anatase thin film (100) surface is doped with silver or nickel. The formulas used are Ti32O72H16, Ag 2Ti30O72H16, and Ni2Ti 30O72H16 with the (100) crystallographic surface exposed and covered with a monolayer of water. Optimization is completed by DFT and PBE functional in VASP software with and without spin polarization. The density of states, absorption spectra, partial density of states, partial charge densities, molecular dynamics, and non adiabatic couplings are compared between the doped models and un-doped as the standard. According to our calculations, holes relax faster than electrons. The information can be used to show the mechanism of how doping the titanium dioxide nanocrystals facilitates photo induced charge transfer at the surfaces, which is useful in understanding photoelectrochemical water splitting.

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

    PubMed

    Velmurugan, Rengasamy; Sreedhar, Bojja; Swaminathan, Meenakshisundaram

    2011-07-30

    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).

  17. Enhanced supercapacitor performances using C-doped porous TiO2 electrodes

    NASA Astrophysics Data System (ADS)

    Chen, Juanrong; Qiu, Fengxian; Zhang, Ying; Liang, Jianzheng; Zhu, Huijun; Cao, Shunsheng

    2015-11-01

    Considerable efforts have been paid to develop electrochemical capacitors with energy storage capability in order to meet the demands of multifunctional electronics. Here we report a facile method to fabricate C-doped porous anatase TiO2. This technique involves the preparation of monodisperse cationic polystyrene nanoparticles (CPN), following sequential deposition of tetrabutylorthotitanate (TBT), and directly carbonizing of CPN. Interestingly, during the process of carbonizing CPN, a phase transition of TiO2 will be happened and whist C-doped porous anatase TiO2 is in situ formed. When this porous C-doped TiO2 is used as electrode material to prepare electrochemical capacitor, it manifests a higher capacitance than the commercial P25, effectively broadening it potential for many practical applications.

  18. 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.

  19. First-principles study on transition metal-doped anatase TiO2

    PubMed Central

    2014-01-01

    The electronic structures, formation energies, and band edge positions of anatase TiO2 doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO2 were constructed by using the 24-atom 2 × 1 × 1 supercell of anatase TiO2 with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO2, lead to the improvement in the photoreactivity of TiO2, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO2 becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response. PMID:24472374

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

    PubMed Central

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2007-10-01

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

  3. Antibacterial activity of TiO2 nanotubes: Influence of crystal phase, morphology and Ag deposition

    NASA Astrophysics Data System (ADS)

    Li, Huirong; Cui, Qiang; Feng, Bo; Wang, Jianxin; Lu, Xiong; Weng, Jie

    2013-11-01

    TiO2 nanotubes on Ti substrate were fabricated by electrochemical anodization. Ag nanoparticles were deposited on the TiO2 nanotubes by a silver mirror reaction. Antibacterial activity of the nanotubes with different structural features was evaluated by a culture test with Escherichia coli bacteria. The anatase nanotubes showed the highest antibacterial activity among three crystal phases including anatase, rutile and amorphous titania. The diameters of the nanotubes affected the antibacterial activity. The two nanotubes with 200 nm and 50 nm diameters had higher antibacterial rate than those with other diameters. The antibacterial activity of the nanotubes was independent on their lengths. Ag-deposited nanotubes exhibited excellent antibacterial activity and its antibacterial rate was up to approximately 100%. TiO2 nanotubes and Ag-deposited nanotubes on titanium should be potential for antibacterial applications in clinics and industry, especially regarding with their reusability.

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

    PubMed

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

    2016-09-28

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

  5. 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.

  6. Investigation of Ag-TiO2 Interfacial Reaction of Highly Stable Ag Nanowire Transparent Conductive Film with Conformal TiO2 Coating by Atomic Layer Deposition.

    PubMed

    Yeh, Ming-Hua; Chen, Po-Hsun; Yang, Yi-Ching; Chen, Guan-Hong; Chen, Hsueh-Shih

    2017-03-29

    The atomic layer deposition (ALD) technique is applied to coat Ag nanowires (NWs) with a highly uniform and conformal TiO2 layer to improve the stability and sustainability of Ag NW transparent conductive films (TCFs) at high temperatures. The TiO2 layer can be directly deposited on Ag NWs with a surface polyvinylpyrrolidone (PVP) coat that acts a bed for TiO2 seeding in the ALD process. The ALD TiO2 layer significantly enhances the thermal stability at least 100 fold when aged between 200-400 °C and also provides an extra function of violet-blue light filtration for Ag NW TCFs. Investigation into the interaction between TiO2 and Ag reveals that the conformal TiO2 shell could effectively prevent Ag from 1D-to-3D ripening. However, Ag could penetrate the conformal TiO2 shell and form nanocrystals on the TiO2 shell surface when it is aged at 400 °C. According to experimental data and thermodynamic evaluation, the Ag penetration leads to an interlayer composed of mixed Ag-Ag2O-amorphous carbon phases and TiO2-x at the Ag-TiO2 interface, which is thought to be caused by extremely high vapor pressure of Ag at the Ag-TiO2 interface at a higher temperature (e.g., 400 °C).

  7. Photocatalytic performance of Fe-doped TiO2 nanoparticles under visible-light irradiation

    NASA Astrophysics Data System (ADS)

    Ali, T.; Tripathi, P.; Azam, Ameer; Raza, Waseem; Ahmed, Arham S.; Ahmed, Ateeq; Muneer, M.

    2017-01-01

    The present work focuses on the synthesis, characterization and photocatalytic activity of a nanosized Fe-doped TiO2 photocatalyst. The samples were synthesized by the sol–gel method and characterized by using techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), UV–visible spectroscopy, photoluminescence (PL) spectroscopy, Raman spectroscopy and Fourier-transform infrared (FTIR). The powder XRD spectra revealed that the synthesized samples are pure and crystalline in nature and show a tetragonal anatase phase of TiO2. The Raman spectroscopy also confirmed the formation of an anatase phase structure in both pure and Fe-doped TiO2 nanoparticles (NPs). The UV–visible and PL spectra illustrated the red shift in Fe-doped TiO2 NPs. The FTIR spectra indicated the vibrational band of the Ti–O lattice. The photocatalytic experimental results demonstrate that Fe-doped TiO2 NPs effectively degrade MB under visible-light illumination. Interestingly, the prepared TiO2 NPs with a dopant concentration of 3.0 mole% showed the maximum photocatalytic activity under investigation.

  8. Structure and high photocatalytic activity of (N, Ta)-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Le, N. T. H.; Thanh, T. D.; Pham, V.-T.; Phan, T. L.; Lam, V. D.; Manh, D. H.; Anh, T. X.; Le, T. K. C.; Thammajak, N.; Hong, L. V.; Yu, S. C.

    2016-10-01

    A hydrothermal method was used to prepare three nano-crystalline samples of TiO2 (S1), N-doped TiO2 (S2), and (N, Ta)-codoped TiO2 (S3) with average crystallite sizes (D) of 13-25 nm. X-ray diffraction studies confirmed a single phase of the samples with a tetragonal/anatase structure. A slight increase in the lattice parameters was observed when N and/or Ta dopants were doped into the TiO2 host lattice. Detailed analyses of extended X-ray absorption spectra indicated that N- and/or Ta-doping into TiO2 nanoparticles influenced the co-ordination number and radial distance (R) of Ti ions in the anatase structure. Concerning their absorption spectra, (N, Ta)-doping narrowed the band gap (Eg) of TiO2 from 3.03 eV for S1 through 2.94 eV for S2 to 2.85 eV for S3. Such results revealed the applicability of these nanoparticles in the photocatalytic field working in the ultraviolet (UV)-visible region. Among these, photocatalytic activity of S3 was the strongest. By using S3 as a catalyst powder, the degradation efficiency of methylene blue solution was about 99% and 93% after irradiation of UV-visible light for 75 min and visible-light for 180 min, respectively.

  9. 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.

  10. Electronic, optical and photocatalytic behavior of Mn, N doped and co-doped TiO2: Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Zhao, Ya Fei; Li, Can; Lu, Song; Liu, Ru Xi; Hu, Ji Yuan; Gong, Yin Yan; Niu, Leng Yuan

    2016-03-01

    The crystal phase structure, surface morphology, chemical states and optical properties of Mn, N mono-doped and co-doped TiO2 nanoparticles were investigated by X-ray powder diffractometry, Raman spectra, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. Meanwhile, geometry structures, formation energies, electronic and optical properties of all systems have been also analyzed by density functional theory. The results showed that the band gap values and the carrier mobility in the valence band, conduction band and impurity levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped TiO2. The number and the carrier mobility of impurity level jointly influence the photocatalytic activity of catalyst under visible-light. Especially, the photocatalytic activity of Mn-2N co-doped TiO2 beyond three-fold than that of pure TiO2 under visible-light.

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

    PubMed

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

    2016-02-24

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

  12. Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping

    NASA Astrophysics Data System (ADS)

    Liu, Zhifeng; Wang, Yun; Peng, Xinli; Li, Yabin; Liu, Zhichao; Liu, Chengcheng; Ya, Jing; Huang, Yizhong

    2012-04-01

    Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

  13. Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping.

    PubMed

    Liu, Zhifeng; Wang, Yun; Peng, Xinli; Li, Yabin; Liu, Zhichao; Liu, Chengcheng; Ya, Jing; Huang, Yizhong

    2012-04-01

    Hydrophilic Cu-TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants.

  14. Photoinduced superhydrophilicity of TiO2 thin film with hierarchical Cu doping

    PubMed Central

    Liu, Zhifeng; Wang, Yun; Peng, Xinli; Li, Yabin; Liu, Zhichao; Liu, Chengcheng; Ya, Jing; Huang, Yizhong

    2012-01-01

    Hydrophilic Cu–TiO2 thin films with a gradient in the Cu concentration were prepared on glass by layer-by-layer dip-coating from TiO2 precursors. The effects of the Cu doping on the structure and properties of TiO2 self-cleaning thin films are discussed. The Cu gradient markedly affects the hydrophilicity of the films, with the water contact angle significantly reduced compared with those of the pure or uniformly doped TiO2 thin films. This enhanced hydrophilicity is explained by the more efficient absorption of the solar light and by the reduced recombination of photoexcited electrons and holes in the TiO2 films containing a gradient of Cu dopants. PMID:27877479

  15. Anchoring Nitrogen-Doped TiO2 Nanocrystals on Nitrogen-Doped 3D Graphene Frameworks for Enhanced Lithium Storage.

    PubMed

    Liu, Xiao-Wu; Yang, Zhen-Zhong; Pan, Fu-Sen; Gu, Lin; Yu, Yan

    2017-02-03

    An advanced architecture design of nitrogen-doped TiO2 anchored on nitrogen-doped 3D graphene framework composites (denoted as N-TiO2 /N-3D GFs) have been fabricated by a facile template process and further NH3 treatment. The 3D graphene framework allows the electrolyte to penetrate into the inverse opal structure, and possesses high electronic conductivity. The close contact between the N-TiO2 and the graphene suppresses the growth and aggregation of TiO2 nanoparticles during heating process, leading to decreased Li(+) diffusion length. The N-doping in both TiO2 and the graphene matrix could improve the electronic conductivity on the TiO2 particle surface and between adjacent particles. As expected, when used as an anode for Li-ion batteries (LIBs), the N-TiO2 /N-3D GFs composite delivers an excellent reversible capacity of 165 mA h g(-1) after 200 cycles at 100 mA g(-1) and an outstanding rate capability of 114 mA h g(-1) after 1000 cycles at 1 Ag(-1) . With rational design, this strategy could be extended to other electrode materials that may hold great promise for the development of high energy storage systems.

  16. Efficient photon management with Ag nanoparticles coated TiO2 nanowire clusters for photodetector application

    NASA Astrophysics Data System (ADS)

    Ngangbam, Chitralekha; Mondal, Aniruddha; Choudhuri, Bijit

    2015-09-01

    TiO2 nanowire clusters (NWCs) covered with Ag nanoparticles (NPs) were synthesized on Si substrates using GLAD technique. Ag NPs/TiO2 NWCs showed enhanced optical absorption all over the spectrum compared to bare TiO2 NWCs. The leakage current of the TiO2 NWCs device (-10.8 μA) was reduced by ˜9 × 103 times for Ag NPs/TiO2 NWCs detector (-1.2 nA) at -1 V applied bias. Ag NPs/TiO2 NWCs detector exhibited maximum photoresponsivity ˜2.4 times (-2 V) as compared to the bare TiO2 NWCs detector. Using 10 K photocapacitance measurement, a sharp peak at 355 nm (˜3.5 eV) was detected due to the main band transition. The other sub band gap defects were observed within 410-490 nm along with a broad hump between 595-700 nm. The light dependent capacitance-time (I-T) characteristic of the Ag/TiO2 NWCs detector shows rise-time ( T r ) of 9.6 s and decay time ( T d ) of 10 s. [Figure not available: see fulltext.

  17. Synthesis and characterization of Ag deposited TiO2 particles by laser ablation in water

    NASA Astrophysics Data System (ADS)

    Liu, C. H.; Hong, M. H.; Zhou, Y.; Chen, G. X.; Saw, M. M.; Hor, A. T. S.

    2007-12-01

    Ag deposited TiO2 (Ag/TiO2) particles were synthesized by laser ablation of silver and titanium targets in de-ionized (DI) water. Post-annealing makes the structure stable and the materials change to crystalline state. It is a new approach to form Ag/TiO2 particles with a simple system and non-toxic materials. TiO2 particles with size from 20 to 30 nm coated with silver nano-clusters were observed. The silver nano-clusters can enhance the absorption capability of TiO2 photocatalysts. UV-vis spectrum analysis shows that there is a strong absorption peak at around 400 nm. It is attributed to Ag nanoparticles surface plasmon resonance (SPR) effect. This effect helps to improve the spectral characteristics of TiO2 nanoparticles with its absorption spectra shifted to a longer wavelength region. From the above properties, Ag/TiO2 nanoparticles would have new potential applications in photocatalyst and photo-anode.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. Photocatalytical removal of fluorouracil using TiO2-P25 and N/S doped TiO2 catalysts: A kinetic and mechanistic study.

    PubMed

    Koltsakidou, Α; Antonopoulou, M; Εvgenidou, Ε; Konstantinou, I; Giannakas, A E; Papadaki, M; Bikiaris, D; Lambropoulou, D A

    2017-02-01

    In the present study, the photocatalytic activity of TiO2-based photocatalysts toward degradation and mineralization of the anti-cancer drug 5-fluorouracil (5-FU) in aqueous phase was investigated under simulated solar and visible irradiation. Commercial TiO2 (P25) and N/S-doped TiO2 catalysts synthesized by a simple sol-gel method were used as photocatalysts. TiO2 P-25 was found to be the most photoactive catalyst for the removal of 5-FU, under simulated solar irradiation. Among N/S-doped TiO2 catalysts, the one with molar Ti:N/S ratio equal to 0.5 was the most efficient under simulated solar irradiation. In contrast, under visible irradiation the catalyst with equimolar Ti:N/S ratio showed the highest performance for the removal of 5-FU. Scavenging experiments revealed that HO radicals and h(+) were the major reactive species mediating photocatalytic degradation of 5-FU using TiO2 P-25 and N/S-doped TiO2 catalysts, under simulated solar irradiation. On the other hand, the essential contribution of (1)O2 and O2(-) in the degradation of 5-FU under visible light was proved. The transformation products (TPs) of 5-FU, were identified by LC-MS-TOF suggesting that defluorination followed by hydroxylation and oxidation are the main transformation pathways, under all the studied photocatalytic systems.

  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. 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.

  2. Microporous Ni-doped TiO2 film photocatalyst by plasma electrolytic oxidation.

    PubMed

    Yao, Zhongping; Jia, Fangzhou; Tian, Shujun; Li, ChunXiang; Jiang, Zhaohua; Bai, Xuefeng

    2010-09-01

    Ni-doped TiO2 film catalysts were prepared by a plasma electrolytic oxidation (PEO) method and were mainly characterized by means of SEM, EDS, XRD, XPS, and DRS, respectively. The effects of Ni doping on the structure, composition and optical absorption property of the film catalysts were investigated along with their inherent relationships. The results show that the film catalyst is composed of anatase and rutile TiO2 with microporous structure. Doping Ni changes the phase composition and the lattice parameters (interplanar crystal spacing and cell volume) of the films. The optical absorption range of TiO2 film gradually expands and shifts to the red with increasing dosages. Both direct and indirect transition band gaps of the TiO2 films are deduced consequently. Moreover, the photocatalytic activity of the film catalysts for splitting Na2S+Na2SO3 solution into H2 is enhanced by doping with an appropriate amount of Ni. The as-prepared TiO2 film catalyst doping with 10 g/L of Ni(Ac)2 presents the highest photocatalytic reducing activity.

  3. 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

    2016-03-07

    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.

  4. Ultrasound aided photochemical synthesis of Ag loaded TiO2 nanotube arrays to enhance photocatalytic activity.

    PubMed

    Sun, Lan; Li, Jing; Wang, Chenglin; Li, Sifang; Lai, Yuekun; Chen, Hongbo; Lin, Changjian

    2009-11-15

    This work presents a novel approach for preparing TiO(2) nanotube array photocatalyst loaded with highly dispersed Ag nanoparticles through an ultrasound aided photochemical route. The Ag content loaded on the array was controlled by changing the concentration of AgNO(3) solution. The Ag-TiO(2) nanotube arrays were characterized by SEM, XRD, XPS and UV-vis absorption. The effects of Ag content on the photoelectrochemical (PEC) property and photocatalytic activity of TiO(2) nanotube array electrode were studied. The results showed that Ag loading significantly enhanced the photocurrent and photocatalytic degradation rate of TiO(2) nanotube array under UV-light irradiation. The photocurrent and photocatalytic degradation rate of Ag-TiO(2) nanotube array prepared in 0.006 M AgNO(3) solution were about 1.2 and 3.7 times as that of pure TiO(2) nanotube array, respectively.

  5. Enhanced efficiency of dye-sensitized TiO2 solar cells (DSSC) by doping of metal ions.

    PubMed

    Ko, Kyung Hyun; Lee, Young Cheol; Jung, Young Jin

    2005-03-15

    Doped TiO(2) semiconductor powders were synthesized using Al and W as photovoltaic property-enhancing impurities. Al-doped TiO(2) electrodes increased open-circuit voltage (V(oc)), but reduced short-circuit current (I(sc)). In contrast, W-doped TiO(2) had an opposite effect. However, dye-sensitized solar cell efficiency fabricated with doped TiO(2) was remarkably better than that of undoped TiO(2). It seems that these phenomena were related to electrical surface-state modifications induced by metal-ion dopants. These modifications led to significant changes in powder aggregation, charge transfer kinetics, and dye adsorption characteristics. The highest efficiency was found by using (Al+W)-doped TiO(2) nanopowders.

  6. Characterization of nanostructured TiO2:Ag films: structural and optical properties

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    TiO2:Ag nanocomposites have been prepared by sol-gel method with varying silver concentration. Different technological approaches are employed to study the formation of Ag nanoparticles in titanium dioxide matrix. The obtained thin films are either thermally treated at temperatures from 300 to 600oC or UV irradiated for 15 minutes between layer deposition. XRD and FTIR studies reveal that Ag is incorporated in TiO2 films as nanoparticles and no Ag oxide phases are detected. Optical characterization performed by UV-VIS spectroscopy confirms the formation of silver nanoparticles. The influence of thermal treatment and UV radiation on the optical and structural properties is studied.

  7. 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.

  8. Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.

    PubMed

    Yang, Chang-Hu; Ma, Zhong-Quan

    2012-08-01

    TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples.

  9. 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.

  10. Enhanced photocatalytic activity of N-doped TiO2 nanocrystals with exposed {001} facets

    NASA Astrophysics Data System (ADS)

    Li, Di; Chen, Fen; Jiang, Deli; Shi, Weidong; Zheng, Wenjun

    2016-12-01

    N-doped TiO2 nanocrystals with exposed {001} facets have been synthesized by a two-step method. Firstly, we synthesized anatase TiO2 nanocrystals with exposed {001} facets by an original hydrothermal method using HBF4 and n-BA to coordinated the regulation of size and morphology. Then, ethylenediamine has been used as N dopant source to dope with the as-prepared TiO2 nanocrystals. The effects of both HBF4 and n-BA in synthesis of anatase TiO2 nanocrystals with exposed {001} facets have been investigated. The enlarged localized profiles of the XRD pattern and XPS spectra demonstrate the existence of N element. The photocatalytic property studies showed that the N-doped TiO2 nanocrystals with exposed {001} facets exhibited much higher photocatalytic activity than that of the N-doped P25, which might be ascribed to the high percentage of exposed {001} facets. In addition, the stability study suggests that the as-synthesized photocatalyst is a promising material for the application of wastewater purification.

  11. Synthesis and photocatalytic activities of Nd-doped TiO2 mesoporous microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xijian; Sun, Yangang; Wang, Yeying; Zhang, Lijuan; Lu, Jie

    2016-11-01

    Nd-doped TiO2 mesoporous microspheres with possessing regular micro/nanostructure were synthesized by a simple and facile method. The structure and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms and UV-Visible absorbance spectroscopy. It was revealed that Nd-doped TiO2 mesoporous microspheres are composed of primary nanoparticles with a particle size of ˜25nm. The photocatalytic activities of all the samples were evaluated by degradation methyl orange (MO) in aqueous solution as a model reaction under xenon lamp light irradiation. The results showed that the doped samples demonstrated a higher photocatalytic activity than TiO2 mesoporous microspheres, and the MO of 10mg/mL almost could be completely degraded by the Nd-doped TiO2 mesoporous sample (the dosage of Nd salt to TiO2 is 6%) under xenon lamp light irradiation within 1h.

  12. Visible light active photocatalytic degradation of bisphenol-A using nitrogen doped TiO2.

    PubMed

    Venkatachalam, N; Vinu, A; Anandan, S; Arabindoo, Banumathi; Murugesan, V

    2006-08-01

    Nitrogen doped titania was prepared by low temperature sol-gel method using titanium precursor and nitrogen containing bases like triethylamine and tetramethyl ammonium hydroxide compounds. The materials were characterized by XRD, BET, SEM, XPS, DRS-UV, and FT-IR techniques. DRS-UV study substantially indicates shift of the absorption edge of TiO2 to lower energy region. The phase composition, crystallinity, specific surface area, and visible light activity of nitrogen doped titania depend upon the preparation conditions. Photocatalytic degradation of bisphenol-A in aqueous medium was investigated by TiO2 and nitrogen doped TiO2 under visible light irradiation in a batch photocatalytic reactor. The results indicate higher visible light activity for nitrogen doped TiO2 than commercial TiO2 (Degussa P25) for bisphenol-A degradation. The influence of various parameters such as initial concentration of bisphenol-A, catalyst loading and pH was examined for maximum degradation efficiency.

  13. Synthesis and Modification of Zn-doped TiO2 Nanoparticles for the Photocatalytic Degradation of Tetracycline.

    PubMed

    Pang, Shuo; Huang, Ji-Guo; Su, Yun; Geng, Bo; Lei, Su-Yuan; Huang, Yu-Ting; Lyu, Cong; Liu, Xing-Juan

    2016-09-01

    The synthesis of Zn-doped TiO2 nanoparticles by solgel method was investigated in this study, as well as its modification by H2 O2 . The catalyst was characterized by transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, UV-visible reflectance spectra and X-ray photoelectron spectroscopy (XPS). The results indicated that doping Zn into TiO2 nanoparticles could inhibit the transformation from anatase phase to rutile phase. Zn existed as the second valence oxidation state in the Zn-doped TiO2 . Zn-doped TiO2 that was synthesized by 5% Zn doping at 450°C exhibited the best photocatalytic activity. Then, the H2 O2 modification further enhanced the photocatalytic activity. Zn doping and H2 O2 modifying narrowed the band gap and efficiently increased the optical absorption in visible region. The optimal degradation rate of tetracycline by Zn-doped TiO2 and H2 O2 modified Zn-doped TiO2 was 85.27% and 88.14%. Peroxide groups were detected in XPS analysis of H2 O2 modified Zn-doped TiO2 , favoring the adsorption of visible light. Furthermore, Zn-doped TiO2 modified by H2 O2 had relatively good reusability, exhibiting a potential practical application for tetracycline's photocatalytic degradation.

  14. The effect of multiwalled carbon nanotube doping on the CO gas sensitivity of TiO2 xerogel composite film

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Seok; Ha, Tae-Jung; Hong, Min-Hee; Park, Chang-Sun; Park, Hyung-Ho

    2013-03-01

    A simple sol-gel method was applied for the synthesis of 0.01 wt% multiwalled carbon nanotubes (MWCNTs)-doped TiO2 xerogel composite film. The film's CO gas sensing properties were then evaluated. Doped MWCNTs were coated with TiO2 and distributed on a TiO2 xerogel matrix. The TiO2 xerogel showed an anatase structure after heat treatment at 450 °C under vacuum. The specific surface area of the composite material was larger than the pure TiO2 xerogel material. The CO gas sensitivity of the MWCNTs(0.01 wt%)-doped TiO2 xerogel composite film was found to be seven times higher than that of pure TiO2 xerogel film and to have good stability. This higher gas-sensing property of the composite film was due to both an increase of specific surface area and the n-p junction structure of the TiO2 xerogel coated on MWCNTs. The electrons generated from TiO2 after adsorption of CO gas induces electron transfer from the TiO2 to the MWCNTs. This induces a characteristic change in the MWCNTs from p-type to n-type, and the resistance of MWCNTs-doped TiO2 xerogel composite sensor is therefore decreased.

  15. Fe-Doped TiO2 Thin Films for CO Gas Sensing

    NASA Astrophysics Data System (ADS)

    Kumar, Mukesh; Kumar, Dinesh; Gupta, Anil Kumar

    2015-01-01

    Fe-doped TiO2 thin films were prepared by the sol-gel technique on silicon substrate. The thin films were evaluated for detection of carbon monoxide (CO) gas at room temperature. The TiO2 films were characterized by x-ray diffraction (XRD) analysis, field-emission scanning electron microscopy, and ultraviolet-visible (UV) spectroscopy. The characterization revealed that, as the doping concentration was increased, the grain size decreased. XRD patterns revealed the phase transition from rutile to anatase with addition of different percentages (weight/volume) of Fe. The bandgap determined from UV spectroscopy was found to decrease with increasing Fe doping concentration. Fe doping was observed to have a significant effect on the resistivity of the doped TiO2 thin films. The gas sensing behavior of the films was studied by exposure to different concentrations of CO gas with measurement of the electrical resistance. It was observed that Fe-doped (7% weight/volume) TiO2 exhibited high sensitivity and good response/recovery on exposure to CO gas in the concentration range from 100 ppm to 900 ppm in Ar.

  16. 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.

  17. Plasmonic Ag deposited TiO2 nano-sheet film for enhanced photocatalytic hydrogen production by water splitting

    NASA Astrophysics Data System (ADS)

    Liu, Enzhou; Kang, Limin; Yang, Yuhao; Sun, Tao; Hu, Xiaoyun; Zhu, Changjun; Liu, Hanchen; Wang, Qiuping; Li, Xinghua; Fan, Jun

    2014-04-01

    TiO2 nano-sheet film (TiO2 NSF) was prepared by a hydrothermal method. Ag nanoparticles (NPs) were then deposited on the surface of TiO2 NSF (Ag/TiO2 NSF) under microwave-assisted chemical reduction. The prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) absorption spectroscopy, x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and Raman scattering spectroscopy. The results revealed that the Ag NPs were well dispersed on the anatase/rutile mixed-phase TiO2 nano-sheet surface with a metallic state. The visible light absorption and Raman scattering of TiO2 were enhanced by Ag NPs based on its surface plasmon resonance effect. Besides, Ag NPs could also effectively restrain the recombination of photogenerated electrons and holes. Photocatalytic water splitting was conducted on the films to obtain hydrogen, and the experimental results indicated that plasmonic Ag NPs could greatly enhance the photocatalytic activity of TiO2 due to the synergistic effect between electron transfer and surface plasmon resonance enhanced absorption. The hydrogen yield obtained from the optimal sample reached 8.1 μmol cm-2 and the corresponding energy efficiency was about 0.47%, which was 8.5 times higher than that of pure TiO2 film. Additionally, the formation mechanism of TiO2 nano-sheet film is preliminarily discussed.

  18. 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

  19. Synthesis and characterization of zinc doped nano TiO2 for efficient photocatalytic degradation of Eriochrome Black T

    NASA Astrophysics Data System (ADS)

    Singla, Pooja; Sharma, Manoj; Singh, Kulvir; Pandey, O. P.

    2013-06-01

    Sol-gel method was used to synthesize undoped and zinc doped TiO2 with varied dopant concentrations using titanium tetraisopropoxide and zinc acetate as precursors. The synthesized catalyst samples were characterized by various techniques such as X-ray powder diffraction (XRD), UV-vis diffuse reflectance (DRS). The photocatalytic activity was determined by means of degradation of azo dye Eriochrome Black T. The results revealed that Zn doped TiO2 nanoparticles exhibited better results as compared to undoped TiO2 nanoparticles. Zn doped TiO2 (0.7mol %) nanoparticles exhibited the highest photocatalytic activity.

  20. Zirconium doped TiO2 thin films deposited by chemical spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Juma, A.; Oja Acik, I.; Oluwabi, A. T.; Mere, A.; Mikli, V.; Danilson, M.; Krunks, M.

    2016-11-01

    Chemical spray pyrolysis (CSP) is a flexible deposition technique that allows for mixing of the precursor solutions in different proportions suitable for doping thin films. The CSP method was used to dope TiO2 thin films with Zr by adding zirconium(IV) acetylacetonate into a solution of titanium(IV) isopropoxide in ethanol stabilized by acetylacetone at [Zr]/[Ti] of 0, 5, 10 and 20 at%. The Zr-doped TiO2 thin films were uniform and homogeneous showing much smaller grains than the undoped TiO2 films. Zr stabilized the anatase phase to temperatures above 800 °C depending on Zr concentration in the spray solution. The concentration of Zr determined by XPS was 6.4 at% for the thin film deposited from the 20 at% solution. According to AFM studies, Zr doping decreased the root mean square roughness of TiO2 film from 5.9 to 1.1 nm. An XRD study of samples with the highest Zr amount showed the ZrTiO4 phase started forming after annealing at 800 °C. The optical band gap for TiO2 decreased from 3.3 eV to 3.0 eV after annealing at 800 °C but for the TiO2:Zr(20) film it remained at 3.4 eV. The dielectric constant increased by more than four times with Zr-doping and this was associated with the change in the bond formations caused by substitution of Ti by Zr in the lattice.

  1. 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.

  2. Mn-doped TiO2 thin films with significantly improved optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Lu, Liu; Xia, Xiaohong; Luo, J. K.; Shao, G.

    2012-12-01

    TiO2 thin films with various Mn doping contents were fabricated by reactive magnetron sputtering deposition at 550 °C and their structural, optical and electrical properties were characterized. All films were made of densely packed columnar grains with a fibrous texture along the normal direction of the substrate. The as-deposited structure in the pure TiO2 film consisted of anatase grains with the [1 0 1] texture. Mn incorporation stabilized the rutile phase and induced lattice contraction in the [1 0 0] direction. The texture in the Mn-doped films changed from [1 1 0] to [2 0 0] with increasing Mn content. The incorporation of Mn in the TiO2 lattice introduced intermediate bands into its narrowed forbidden gap, leading to remarkable red-shifts in the optical absorption edges, together with significantly improved electrical conductivity of the thin films. Hall measurement showed that the incorporation of Mn-induced p-type conductivity, with hole mobility in heavily doped TiO2 (˜40% Mn) being about an order higher than electron mobility in single-crystal rutile TiO2. Oxygen vacancies, on the other hand, interacted with substitutional Mn atoms to reduce its effect on optical and electrical properties.

  3. Electronic and optical properties study on Fesbnd B co-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Li, Xuechao; Shi, Jianhao; Chen, Hao; Wan, Rundong; Leng, Chongyan; Lei, Ying

    2016-09-01

    We investigate the density of states and optical properties for Fe, 2B and (Fe, 2B) doped TiO2 with DFT calculations. The calculated results reveal mono-doping introduces midgap states which are half-occupied and easy to become the recombination centers of charge carriers, thus inhibiting the enhancement of photocatalystic activity. The coupling of 2p-3d states in the (Fe, 2B) compensated co-doped TiO2 makes gap states couple with the valence bands edge, thus greatly causing the band gap narrowing and higher visible light absorption. Moreover, the gap states cannot become recombination centers of the photoexcited carriers, thus promoting the separation of electron-hole pairs, prolonging the lifetime of carriers. The analysis of electron density indicates more electrons from Fe transfer to adjacent B, realizing the charge compensation and forming a stronger Fesbnd B bond. Therefore, the (Fe, 2B) compensated co-doped TiO2 exhibits the higher visible-light photocatalystic activity than those of pure and solely doped TiO2.

  4. 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.

  5. Plasmonic Control and Stabilization of Asymmetric Light Scattering from Ag Nanocubes on TiO2.

    PubMed

    Saito, Koichiro; Setoura, Kenji; Ito, Syoji; Miyasaka, Hiroshi; Mitsuda, Yoshitaka; Tatsuma, Tetsu

    2017-03-29

    When plasmonic nanoparticles are placed on a highly refractive semiconductor substrate, we can expect three different effects: (i) resonance mode splitting, (ii) asymmetric light scattering based on the split modes, and (iii) site-selective nanoetching due to plasmon-induced charge separation (PICS) at the nanoparticle-semiconductor interface. Here, we develop novel photofunctional materials by taking advantage of those three effects. More specifically, we control the asymmetric scattering of Ag nanocubes on TiO2 by PICS, so as to develop materials for photodrawing of one-way visible translucent images and multicolor scattering images. The one-way visible translucent images, which are translucent scattering images visible only from the back side, are drawn by anaerobic bottom-selective etching of the Ag nanocubes. For drawing the multicolor scattering images, a scattering color of Ag nanocubes is changed from yellow to green by the anaerobic bottom-selective etching and from yellow to red by aerobic nonselective etching. We also theoretically and experimentally examined the contribution of a possible thermal effect to the nanoetching, and revealed that the contribution is negligible; Ag nanocubes on TiO2 are stable even at 473 K for 2 h in the dark, whereas the theoretically expected temperature increase under light is less than 1 K. In addition, we developed methods to stabilize the Ag nanocubes by inactivating PICS. When Ag nanocubes on TiO2 are coated with a thin polymer layer, PICS is decelerated and the stability is improved. Replacing TiO2 with diamond, which does not accept electrons from plasmonic nanoparticles, is also an effective method to stabilize the nanocubes.

  6. Effect of Au clustering on ferromagnetism in Au doped TiO2 films: theory and experiments investigation

    NASA Astrophysics Data System (ADS)

    Zou, Zhaorui; Zhou, Zhongpo; Wang, Haiying; Yang, Zongxian

    2017-01-01

    In this paper, we investigated the physical properties especially the magnetic properties of the TiO2 films and Au cluster doped TiO2 films fabricated by sol-gel and sputtering methods combined experiments and first-principles calculations. All the samples annealed under air and N2 atmosphere respectively exhibit room temperature ferromagnetism with the crystal phase of anatase. The values of the saturation magnetizations are in the order of Au δ-doped TiO2 (annealed in N2)>undoped TiO2 (annealed in air)>Au δ-doped TiO2 (annealed in air). The first principles calculation results show that the formation energy of Au cluster doped TiO2 films is lower than that of the oxygen vacancy and Au cluster codoped TiO2 films. The effects of the Au cluster dopant are the retard of the formation of surface oxygen vacancy and the electrons transfer from 3d states of Ti atoms to Au 5d states in Au cluster doped TiO2 films. The codoping of surface oxygen vacancies, bulk oxygen vacancies and Au clusters led to the spin-split of Ti 3d and O 2p in Au cluster doped TiO2 films (annealed in N2) which yield the highest saturation magnetization.

  7. 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.

  8. TiO2 nanofibers coated with rGO and Ag2O for promoting visible light photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Zhou, Yun; Wang, Yuan; OuYang, Xiaoping; Liu, Lixin; Zhu, Wenjun

    2017-03-01

    Due to the increase in environmental pollution, highly efficient photocatalysts with enhanced visible light photocatalytic activity have attracted considerable attention. In this work, TiO2/reduced graphene oxide (rGO)/Ag2O nanoheterostructures (NHs) based photocatalysts are successfully synthesized and a markedly higher visible light photocatalytic activity is achieved, of which at least 96% of Rhodamine B (RhB) molecules are decomposed by the TiO2/rGO/Ag2O NHs after 120 min visible light irradiation, but only 30% of RhB molecules are decomposed by pure TiO2 nanofibers (NFs). Furthermore, the influence of rGO volume ratio in TiO2/rGO/Ag2O NHs photocatalysts on visible light photocatalysis is studied, and the result shows that the sample with 5 vol% rGO exhibits the highest visible light photocatalytic activity. The much enhanced visible light photocatalytic performance of the ternary TiO2/rGO/Ag2O NHs can be ascribed to the intense visible light absorption of Ag2O, the excellent electron conductivity of 2D rGO and the matched energy level of TiO2, Ag2O, and rGO, for efficient boost of the photogenerated charge carriers transfer and separation at the interface of hierarchical TiO2/rGO/Ag2O NHs.

  9. Theoretical study of magnetism in transition-metal-doped TiO2 and TiO2-δ

    NASA Astrophysics Data System (ADS)

    Errico, L. A.; Rentería, M.; Weissmann, M.

    2005-11-01

    In recent years there has been an intense search for room temperature ferromagnetism in semiconductors doped with dilute magnetic impurities, in particular, oxides. In this work we study the structural, electronic, and magnetic properties of doped rutile TiO2 for two different impurity concentrations (25% and 6.25%), considering different distributions of the impurities in the host lattice. Calculations were performed with ab initio methods, assuming that the magnetic impurities substitutionally replace the Ti ions. Our results show that a local magnetic moment appears in the cases of Mn, Fe, and Co impurities, but not in the cases of Ni and Cu impurities. They also show that in the system Ti1-xCoxO2 the magnetic ions align ferromagnetically, while in Ti1-xMnxO2 and Ti1-xFexO2 the antiferromagnetic alignment is energetically favorable. We have also studied the effect of oxygen vacancies, which turned out to be very important. Their presence decreases the energy required to introduce the impurities in the host lattice and reciprocally, the presence of impurities is related to a higher vacancy concentration. The pairs impurity-nearest-neighbor oxygen vacancy seem to be the energetically preferred structures and to produce the highest local magnetic moments. Ni and even Cu impurities acquire magnetic moments in this environment.

  10. A Simple Method for the Preparation of TiO2 /Ag-AgCl@Polypyrrole Composite and Its Enhanced Visible-Light Photocatalytic Activity.

    PubMed

    Yao, Tongjie; Shi, Lei; Wang, Hao; Wang, Fangxiao; Wu, Jie; Zhang, Xiao; Sun, Jianmin; Cui, Tieyu

    2016-01-01

    A novel and facile method was developed to prepare a visible-light driven TiO2 /Ag-AgCl@polypyrrole (PPy) photocatalyst with Ag-AgCl nanoparticles supported on TiO2 nanofibers and covered by a thin PPy shell. During the synthesis, the PPy shell and Ag-AgCl nanoparticles were prepared simultaneously onto TiO2 nanofibers, which simplified the preparation procedure. In addition, because Ag-AgCl aggregates were fabricated via partly etching the Ag nanoparticles, their size was well controlled at the nanoscale, which was beneficial for improvement of the contact surface area. Compared with reference photocatalysts, the TiO2 /Ag-AgCl@PPy composite exhibited an enhanced photodegradation activity towards rhodamine B under visible-light irradiation. The superior photocatalytic property originated from synergistic effects between TiO2 nanofibers, Ag-AgCl nanoparticles and the PPy shell. Furthermore, the TiO2 /Ag-AgCl@PPy composite could be easily separated and recycled without obvious reduction in activity.

  11. Non-UV based germicidal activity of metal-doped TiO2 coating on solid surfaces.

    PubMed

    Liu, Li-fen; Barford, John; Yeung, King Lun; Si, Grace

    2007-01-01

    A stain-based screening method was developed to screen different catalyst coatings for their germicidal activity. A Baclight dead/live bacteria viability kit (invitrogen, molecular probes) was used for staining the cell. The screening was carried out following a standard procedure. This included loading cell suspension to solid surface and maintaining contact for 30 min, then staining with a mixture containing dyes. The stained cells were observed using an epifluorescent microscope and photographed with a CCD camera under UV. Metal-doped TiO2 coatings on Al plates were prepared and tested for non-UV germicidal activity without using UV. It was tested using model microorganisms such as Bakers Yeast (Saccharomyces cerevisiae), Bacillus subtilis, Pseudomonas putida, and Escherichia coli. On the basis of the germicidal activity of catalyst and the degree of damage caused to the cells, the stained cells may appear green (viable), green with red or yellow nuclei and yellow (compromised) or red (nonviable). According to their stained color, cells were counted to calculate the percentage of dead, live, and compromised cells. Compromised cells are cells that grow very slowly after reculturing indicating a degree of reversible cell damage. Screening the germicidal activity using this staining method is accurate and efficient, and requires less time than the culture-based method. A modification to the procedure for measuring germicidal activity of rough surfaces or fibrous coatings was developed. Both TiO2 and metal-doped TiO2 (Ag, Pt, Au, Cu) possess non-UV based germicidal activity. The germicidal activity of TiO2 was found to be related with its wetting property and can be improved by UV irradiation before testing. It is not greatly affected by contact time, indicating a fast acting germicidal activity.

  12. 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.

  13. 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...

  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. Using Ag-embedded TiO2 nanotubes array as recyclable SERS substrate

    NASA Astrophysics Data System (ADS)

    Ling, Yunhan; Zhuo, Yuqing; Huang, Liang; Mao, Duolu

    2016-12-01

    A simple strategy for synthesizing Ag-loaded TiO2 nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO2 nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

  16. Synthesis of Br-doped TiO2 hollow spheres with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Wang, Qianqian; Zhu, Shengli; Liang, Yanqin; Cui, Zhenduo; Yang, Xianjin; Liang, Chunyong; Inoue, Akihisa

    2017-02-01

    The Br-doped hollow TiO2 photocatalysts were prepared by a simple hydrothermal process on the carbon sphere template following with calcination at 400 °C. The structure and properties of photocatalysts were characterized by X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscopy, N2 desorption-adsorption, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The TiO2 hollow spheres are in diameter of 500 nm with shell thickness of 50 nm. The shell is composed of small anatase nanoparticles with size of about 10 nm. The TiO2 hollow spheres exhibit high crystalline and high surface area of 89.208 m2/g. With increasing content of Br doping, the band gap of TiO2 hollow spheres decreased from 2.85 to 1.75 eV. The formation of impurity band in the band gap would narrow the band gap and result in the red shift of absorption edge from 395 to 517 nm, which further enhances the photocatalytic activity. The appropriate Br doping improves the photocatlytic activity significantly. The TiO2 hollow spheres with 1.55% Br doping (0.5Br-TiO2) exhibit the highest photocatalytic activity under full light. More than 98% of RhB, MO, and MB can be photodegraded using 0.5Br-TiO2 with concentration of 10 mg/L in 40, 30, and 30 min, respectively. The degradation rate of Br-doped photocatalysts was 40% faster than undoped ones.

  17. Synthesis and Characterization of Rutile TiO2Nanopowders Doped with Iron Ions

    PubMed Central

    2009-01-01

    Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence. PMID:20596442

  18. Preparation and characterization of sulfur-doped TiO(2)/Ti photoelectrodes and their photoelectrocatalytic performance.

    PubMed

    Sun, Haijian; Liu, Huiling; Ma, Jun; Wang, Xiangyu; Wang, Bin; Han, Lei

    2008-08-15

    Sulfur-doped TiO(2)/Ti photoelectrodes were prepared by anodization and characterized by SEM, AFM, XRD, XPS, UV-vis and SPS. The results of investigation indicated that S(4+) and S(6+) were dispersed on the surface of TiO(2) nanoparticles. The doping with an appropriate amount of sulfur expanded the response range of TiO(2)/Ti photoelectrodes to visible light, and enhanced the separation of photoinduced electrons from cavities. The photoelectrocatalytic performance test run with sulfur-doped TiO(2)/Ti photoelectrodes under Xenon light indicated that Na(2)SO(3) concentration of 750 mg/L and voltage of 160 V were the optimal conditions for preparation of sulfur-doped TiO(2)/Ti photoelectrodes.

  19. 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.

  20. Tunability of morphological properties of Nd-doped TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Rehan, Imran; Sultana, Sabiha; Khan, Nauman; Qamar, Zahid; Rehan, Kamran

    2016-11-01

    In this work, an endeavor is made toward structural assessment and morphological variation of titanium dioxide (TiO2) thin films when doped with neodymium (Nd). The electron beam deposition technique was employed to fabricate Nd-based TiO2 thin films on n-Type Si substrates. Nd concentration was varied from 0.0 to 2.0 atomic percent (at.%) under identical growth environments. The films were deposited in an oxygen-deficient environment to cause the growth of rutile phases. Energy dispersive x-ray spectroscopy confirmed the presence and variation of Nd dopant in TiO2. X-ray diffraction analysis showed the transformation of amorphous structures of the as-grown samples to anatase polycrystalline after annealing at 500 °C, while atomic force microscopy exposed linearity in grain density in as-grown samples with doping until 1 at.%. Raman spectrums of as-grown and annealed samples revealed the growth of the anatase phase in the annealed samples. Based on these results it can be proposed that Nd doping has pronounced effects on the structural characteristics of TiO2 thin films.

  1. 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-

  2. 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.

  3. 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.

  4. In3+-doped TiO2 and TiO2/In2S3 nanocomposite for photocatalytic and stoichiometric degradations.

    PubMed

    Stengl, Václav; Opluštil, František; Němec, Tomáš

    2012-01-01

    A novel In(3+)-doped TiO(2) and TiO(2)/In(2)S(3) nanocomposites for photocatalytic degradation of environmental pollutants and stoichiometric degradation of warfare agents were prepared by a homogeneous hydrolysis with urea and thioacetamide, respectively. The prepared samples series TiInTAA were annealed at 600°C. The prepared samples were characterized by X-ray powder diffraction, IR spectroscopy, Raman spectroscopy, specific surface area (BET) and porosity determination. The method of UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photocatalytic activity (PCA) was tested by degradation of Orange dye, whereas stoichiometric activity was studied by degradation of sulfur mustard. Incorporation of In(3+) into titania lattice increases PCA of TiO(2) in the visible light and increases stoichiometric decomposition of sulfur mustard against nondoped TiO(2) as well. PCA of TiO(2)/In(2)S(3) composite depends on the optimal ratio of TiO(2):In(2)S(3) in composite, while the activity for stoichiometric decomposition of sulfur mustards depends on the content of In(2)S(3) in nanocomposite.

  5. Fabrication of TiO2/Ag2O heterostructure with enhanced photocatalytic and antibacterial activities under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Bingkun; Mu, Lilong; Han, Bing; Zhang, Jingtao; Shi, Hengzhen

    2017-02-01

    TiO2/Ag2O heterostructure prepared by a facile in situ precipitation route was used as an effective visible light-driven photocatalyst for degradation of methylene blue (MB) and inactivation of E. coli. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that Ag2O nanoparticles were well distributed on the surface of TiO2 microspheres. The TiO2/Ag2O composite with optimal mass ratio of TiO2 and Ag2O displayed extremely good photodegradation ability and antibacterial capability under visible light irradiation, which was mainly ascribed to the synergistic effect between Ag2O and TiO2, including highly dispersed smaller Ag2O particles, increased visible light absorption and efficient separation of photo-induced charge carriers. Meanwhile, the roles of the radical species in the photocatalysis process were investigated. Our results showed that the TiO2/Ag2O could be used as a dual functional material in water treatment of removing the organic pollutant and killing the bacterium at the same time.

  6. Phosphorus-doped TiO2 catalysts with stable anatase-brookite biphase structure: synthesis and photocatalytic performance.

    PubMed

    Feng, Huajun; Zhang, Min-Hong; Yu, Liya E

    2013-07-01

    Phosphorus-doped (P-doped) TiO2 catalysts with a stable anatase-brookite biphase structure were successfully synthesized by integrating ultrasonication with phosphorus doping and Pluronic P123 surfactant. The synthesized catalysts were characterized using X-ray diffraction, transmission electron microscopy, nitrogen adsorption-desorption, Fourier transform infrared, and UV-visible diffuse reflectance spectra. Ultrasonication facilitates the appearance of brookite phase. Phosphorus doping was demonstrated an effective strategy to stabilize the anatase-brookite biphase structure and inhibits undesirable grain growth. Triblock copolymer Pluronic P123 used in the reaction facilitates the formation of catalyst particles with mesoporous structure and large surface area and prevents particles from agglomeration. The low band-gap of brookite phase enables the synthesized P-doped TiO2 catalysts outperform commercial P25 TiO2 and N-doped TiO2 in the degradation of methylene blue under both solar light and visible light irradiation.

  7. Eu(3+) doped down shifting TiO2 layer for efficient dye-sensitized solar cells.

    PubMed

    Kumar, Vinod; Swami, Sanjay Kumar; Kumar, Anuj; Ntwaeaborwa, O M; Dutta, Viresh; Swart, H C

    2016-12-15

    Europium doped TiO2 (TiO2:Eu(3+)) down-shifting (DS) nanophosphors (NPrs) were synthesized by the solution-combustion method with different concentrations of Eu(3+). The X-ray diffraction results confirmed the formation of a polycrystalline tetragonal structure of the TiO2. The emission of colour of the TiO2:Eu(3+) DS NPr was tuned by varying the doping concentration of Eu(3+). The photoluminescence results confirmed that the TiO2:Eu(3+) DS NPrs converted the UV light into visible light by energy down-conversion process, i.e. down-shifting of high energy UV photons to low energy visible photons. These TiO2:Eu(3+) DS NPrs were used to enhance the efficiency of the Dye sensitized solar cell from 8.32% to 8.80%.

  8. 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.

  9. 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.

  10. Niobium doping induced morphological changes and enhanced photocatalytic performance of anatase TiO2

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chung; Lin, Ting-Han; Chih, Jyun-Sian; Hsiao, Kai-Chi; Wu, Po-Yeh

    2017-04-01

    In order to develop high-performance photocatalysts that are easy to produce even in industrial quantities, we developed a facile method of preparing niobium-doped titanium dioxide (Nb:TiO2) by hydrothermal synthesis and followed by thermal annealing treatment. Niobium-ion doping has been considered as an effective way to improve Nb:TiO2 performance for applications in photocatalysis. Niobium-ion doping of anatase TiO2 induced the morphological changes of Nb:TiO2. Morphological analysis shows sub-microscale fibers at doping concentration lower than 1.00 mol % and nanoscale rods at the doping concentration higher than 1.00 mol %. For the catalyzed photodegradation of methyl orange under visible light irradiation, 0.50 mol % Nb:TiO2 shows the highest activity among the synthesized Nb:TiO2 specimens. Also, for photocatalytic hydrogen generation, its photocatalytic activity is even higher than that of commercial TiO2-P25. In this study, we demonstrated the fabrication of a series of superior Nb:TiO2 specimens. It is a reasonable alternative to commercial TiO2 materials for various applications in the decomposition of organic dyes under visible light irradiation.

  11. Photocatalytic activity of S- and F-doped TiO(2) in formic acid mineralization.

    PubMed

    Dozzi, Maria Vittoria; Livraghi, Stefano; Giamello, Elio; Selli, Elena

    2011-03-02

    Two series of doped titanium dioxide samples (S-TiO(2) and F-TiO(2)) were prepared by the sol-gel method in the presence of different amounts of dopant source (thiourea and NH(4)F, respectively), followed by calcination at 500, 600 or 700 °C, and characterised by BET, UV-vis absorption, XPS, HRTEM, XRD and EPR analyses. Reference undoped materials were prepared by the same synthetic procedure. Their photocatalytic activity under visible light was investigated employing the photocatalytic degradation of formic acid in aqueous suspension as test reaction. S-doped TiO(2) showed a photocatalytic activity quite similar to that of undoped materials. In this regard, the insertion of S, characterised by a relatively large ionic radius, into the TiO(2) crystalline structure appears rather difficult, as confirmed by XPS analysis. On the contrary, moderate F doping was beneficial in increasing the rate of formic acid photocatalytic degradation, especially for photocatalysts calcined at high temperature, consisting of highly crystalline pure anatase, in which the rate of detrimental charge carrier recombination was reduced. For both series of doped materials, high doping levels appear to limit the semiconductor photoactivity, probably due to the formation of a progressively increasing number of charge recombination centres. The EPR characterisation of the investigated doped TiO(2) samples evidenced the presence of nitrogen containing species (nitric oxide radical encapsulated in micro-void, with no photoactivity, and N(b)˙ species, active in visible light sensitisation) and of titanium reduced centres Ti(3+), due to charge imbalance consequent to dopant introduction in the TiO(2) lattice either in anionic (F(-)) or in cationic form (S(6+)).

  12. The photocatalytic and antibacterial activities of neodymium and iodine doped TiO(2) nanoparticles.

    PubMed

    Jiang, Xuefeng; Yang, Lu; Liu, Peng; Li, Xi; Shen, Jian

    2010-08-01

    A series of photocatalysts were synthesized by neodymium and iodine doped TiO(2). The characteristics of neodymium and iodine doped TiO(2) were evaluated by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, and scanning electronic microscope (SEM). In the synthesis process, Nd:I:TiO(2) with different doping content (molar ratios) calcined at different temperature was designed. After the photocatalysts were synthesized under different condition, they were compared with each other by photocatalytic degradation of methylene blue (MB). The most efficient catalyst to degrade MB was Nd combined with I doped TiO(2) with molar ratio of 5:10:100 calcined at 400 degrees C. It is anatase crystal and the average size of crystallites was about 6.0 nm. It has absorption spectrometry in the visible light range of 400-550 nm. In addition, compared with pure TiO(2), the doped catalyst also has intense absorption at 528, 587, 683, 750, 808, and 881 nm. The catalytic efficiency was tested by monitoring the photocatalytic degradation, and detriment of MB and bovine serum albumin (BSA). The antibacterial activities were studied by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that the optimum doping contents was Nd:I:TiO(2)=5:10:100 (molar ratio) calcined at 400 degrees C, and the synthesized catalyst could inhibit E. coli and S. aureus through damaging their outer membrane (even deteriorated completely) by the irradiation of visible light.

  13. Oxygen vacancy enhanced the room temperature ferromagnetism in Ni-doped TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Hou, D. L.; Meng, H. J.; Jia, L. Y.; Ye, X. J.; Zhou, H. J.; Li, X. L.

    2007-04-01

    Ni-doped TiO2 anatase thin films were fabricated by reactive magnetron sputtering on SiO2 substrates. The doping and annealing effects on structure and magnetism for the films have been systematically investigated. The results show that ferromagnetism originated from the doped matrix and enhancement (suppression) of ferromagnetism is strongly correlated with the increase (decrease) of oxygen vacancies in TiO2.

  14. 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.

  15. 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

    2016-06-07

    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.

  16. Controlled synthesis of Ag-coated TiO2 nanofibers and their enhanced effect in photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Guan, Hongyu; Wang, Xiaohong; Guo, Yihang; Shao, Changlu; Zhang, Xintong; Liu, Yichun; Louh, Rong-Fuh

    2013-09-01

    Novel nanostructured Ag/TiO2 hybrid nanofibers (NFs) have been successfully prepared via a simple electrospinning process combined with silver mirror reaction. The Ag/TiO2 NFs demonstrated a unique morphology with evenly distributed Ag nanoparticles uniformly deposited onto the surface of each individual TiO2 NFs. The loading capacity and size of Ag NPs can be easily controlled by varying the silver mirror reaction time. Compared with pristine TiO2 NFs, such heterogeneous Ag/TiO2 nanocomposites exhibited preferable photocatalytic activity during photocatalytic degradation of rhodamine-B under the simulated sunlight irradiation and this enhanced photocatalytic performance was driven by combination and interaction between TiO2 and Ag NPs.

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

    DOE PAGES

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; ...

    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. High adsorption capacity of V-doped TiO2 for decolorization of methylene blue

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Binh; Hwang, Moon-Jin; Ryu, Kwang-Sun

    2012-07-01

    In this study, pure TiO2 (V-TiO2-0) and V-doped TiO2 (V-TiO2-x, x = 1-10 mol%) were synthesized using a new sol-gel method. The adsorption capacity of the V-TiO2-x samples was evaluated by measuring the removal of methylene blue (MB) from aqueous solution via decolorization. Since the adsorption capacity was affected by the specific surface area, the interaction between adsorbate (MB) and adsorbent (V-TiO2-x), and the structure of the adsorbent, the physicochemical properties of the samples were investigated. Among the V-doped TiO2-x samples, the V-TiO2-10 sample showed the highest adsorption capacity, which was 11.36 times greater than that of pure TiO2, removing 85.2% of the MB after 2 h. Moreover, changing the molar ratio of the reactants in the V-TiO2-10 sample improved the performance of the material so that 91.6% of the MB was removed after 2 h.

  19. 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

  20. 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

  1. 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

  2. Facile one-pot synthesis of uniform TiO2-Ag hybrid hollow spheres with enhanced photocatalytic activity.

    PubMed

    Wang, Sunli; Qian, Huanhuan; Hu, Yong; Dai, Wei; Zhong, Yijun; Chen, Jiafu; Hu, Xiao

    2013-01-28

    TiO(2)-Ag hybrid hollow spheres (about 700 nm in diameter) with a highly uniform morphology and good structural stability were facilely prepared via a one-pot hydrothermal method, using carbon spheres as templates followed by an annealing treatment. Through this route, the as-prepared hybrid hollow spheres preserved the uniformity of the initial carbon sphere templates and the loading amount of the Ag nanocrystals can be conveniently varied or controlled by the concentration of the Ag precursor. The investigation of the photocatalytic ability demonstrated that the as-prepared TiO(2)-Ag hybrid hollow spheres possess excellent photocatalytic activity, superior to commercial TiO(2) nanoparticles (Degussa P25), for the degradation of rhodamine B (RhB) and methyl orange (MO) dyes under visible-light illumination. Furthermore, the ˙OH radicals formed during photocatalysis with different Ag content hybrids were revealed by means of a terephthalic acid fluorescence probe method, which uncovers that the Ag content in the TiO(2)-Ag hybrids was crucial to obtain an optimal synergistic effect between the Ag and TiO(2) for the degradation of organic pollutants. Accordingly, the optimum matching for the best photocatalytic activity was investigated thoroughly and a reasonable mechanism was also proposed.

  3. Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer.

    PubMed

    Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

    2017-12-01

    In this paper, N-doped TiO2 (N-TiO2) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO2. To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO2 than un-doped TiO2. The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO2 than to un-doped TiO2. Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO2 than that on un-doped TiO2.

  4. Enhancement of Perovskite Solar Cells Efficiency using N-Doped TiO2 Nanorod Arrays as Electron Transfer Layer

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen-Long; Li, Jun-Feng; Wang, Xiao-Li; Qin, Jian-Qiang; Shi, Wen-Jia; Liu, Yue-Feng; Gao, Hui-Ping; Mao, Yan-Li

    2017-01-01

    In this paper, N-doped TiO2 (N-TiO2) nanorod arrays were synthesized with hydrothermal method, and perovskite solar cells were fabricated using them as electron transfer layer. The solar cell performance was optimized by changing the N doping contents. The power conversion efficiency of solar cells based on N-TiO2 with the N doping content of 1% (N/Ti, atomic ratio) has been achieved 11.1%, which was 14.7% higher than that of solar cells based on un-doped TiO2. To get an insight into the improvement, some investigations were performed. The structure was examined with X-ray powder diffraction (XRD), and morphology was examined by scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) and Tauc plot spectra indicated the incorporation of N in TiO2 nanorods. Absorption spectra showed higher absorption of visible light for N-TiO2 than un-doped TiO2. The N doping reduced the energy band gap from 3.03 to 2.74 eV. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectra displayed the faster electron transfer from perovskite layer to N-TiO2 than to un-doped TiO2. Electrochemical impedance spectroscopy (EIS) showed the smaller resistance of device based on N-TiO2 than that on un-doped TiO2.

  5. Nitrogen-doped TiO2 thin films: photocatalytic applications for healthcare environments.

    PubMed

    Dunnill, Charles W; Parkin, Ivan P

    2011-02-28

    N-doped TiO(2) has for many years received interest as visible light photocatalytic materials. Here we give our perspective on the subject with special consideration towards the use of visible light photocatalysts in the field of antimicrobial materials with applications in healthcare environments. The subject is reviewed and critiqued from synthetic techniques to characterisation and assessment of functional properties. N-doped TiO(2) has huge potential to form commercially viable antimicrobial surfaces that are easily implemented within the healthcare environment. We aim to shed light on the illusive nature of the mechanism of the different types of N-doping and comment on how these affect the properties of the catalysts themselves. Small concentrations of nitrogen doped under mild conditions lead to interstitial doping, which also promotes the creation of oxygen vacancies. Many believe that it is these oxygen vacancies that actually promote the formation of visible light photocatalysis and hence there is an indirect correlation between the interstitial doping and the photocatalysis. As the concentration of interstitial nitrogen increases the oxygen vacancies increase, however the presence of oxygen vacancies in turn encourages substitutional doping which then fills the oxygen vacancies. This cyclic relationship leads to photocatalysts that are very sensitive to changing nitrogen concentration.

  6. 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.

  7. Photocatalysts of Cr Doped TiO2 Film Prepared by Micro Arc Oxidation

    NASA Astrophysics Data System (ADS)

    Wan, Li; Li, Jian-feng; Feng, Jia-you; Sun, Wei; Mao, Zong-qiang

    2008-10-01

    A series of Cr doped TiO2 films were prepared by micro arc oxidation (MAO) using an electrolyte of Na3PO4+K2Cr2O7. X-ray diffraction and scanning electron microscopy revealed that the films mainly consisted of anatase phase with a porous surface morphology. The films have an excellent photocatalytic effect for degradation of methylene blue and decomposition of water under visible light illumination. This arises from the formation of Cr3+/Cr4+ and oxygen vacancy energy levels owing to Cr doping. The former reduces the electron-hole recombination chance, while the latter generates a new gap between the conduction band (CB) and valence band (VB) of TiO2, which lowers the photo energy of the excited electron in the VB to the oxygen vacancy states. The mechanisms for film synthesis during the MAO process are also presented.

  8. Electronic structure and room temperature ferromagnetism of C doped TiO2

    NASA Astrophysics Data System (ADS)

    Ablat, Abduleziz; Wu, Rong; Mamat, Mamatrishat; Ghupur, Yasin; Aimidula, Aimierding; Bake, Muhammad Ali; Gholam, Turghunjan; Wang, Jiaou; Qian, Haijie; Wu, Rui; Ibrahim, Kurash

    2016-10-01

    C-doped TiO2 nanoparticles were successfully synthesized using a simple hydrothermal synthesis method. After this preparation, a portion of the samples were annealed separately in air on the one hand, and in argon on the other, and another portion remained untreated. The results of X-ray diffraction show that the untreated samples primarily display anatase and rutile structures. However, after annealing, the samples displayed the rutile structure only. The Ti K-edge and L-edge Near Edge X-ray Absorption Fine Structure analyses clearly show that C atoms were successfully incorporated into the TiO2 host lattice. All doped samples exhibit ferromagnetism at room temperature. The saturation magnetization (Ms) and coercive fields (Hc) tend to decrease after the samples are annealed in argon and in air. The maximum Ms of the untreated samples was approximately 0.038 emu/g.

  9. Dual Band Electrochromic Devices Based on Nb-Doped TiO2 Nanocrystalline Electrodes.

    PubMed

    Barawi, Mariam; De Trizio, Luca; Giannuzzi, Roberto; Veramonti, Giulia; Manna, Liberato; Manca, Michele

    2017-03-29

    The reliable exploitation of localized surface plasmon resonance in transparent conductive oxides is being pursued to push the developement of an emerging class of advanced dynamic windows, which offer the opportunity to selectively and dynamically control the intensity of the incoming thermal radiation without affecting visible transparency. In this view, Nb-doped TiO2 colloidal nanocrystals are particularly promising, as they have a wide band gap and their plasmonic features can be finely tailored across the near-infrared region by varying the concentration of dopants. Four batches of Nb-doped TiO2 nanocrystals with different doping levels (from 0% to 15% of niobium content) have been used here to prepare highly transparent mesoporous electrodes for near-infrared selective electrochromic devices, capable of dynamically modulating the intensity of the transmitted radiation upon the application of a relatively small bias voltage. An engineered dual band electrochromic device (made of 10%-Nb-doped TiO2 nanocrystals) has been eventually fabricated. It was shown to provide two complementary spectroelectrochemical responses, which can be independently controlled through the intensity of the applied potential: a large variation of the optical transmittance in the near-infrared region (by the intensification of the localized surface plasmon scattering) was achievable in the 0-3 V voltage window, reaching values greater than 64% in the spectral range from 800 to 2000 nm, whereas the visible absorption could also be intensively varied at higher potentials (from 3 to 4 V), driven by Li intercalation into the TiO2 anatase lattice.

  10. 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.

  11. 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.

  12. Synthesis of iron-doped TiO2 for degradation of reactive Orange16.

    PubMed

    Safari, Mojtaba; Talebi, Rasoul; Rostami, Mohammad Hossein; Nikazar, Manouchehr; Dadvar, Mitra

    2014-01-09

    In this study the optimum conditions for preparing the iron-doped TiO2 nanoparticles were investigated. Samples were synthesized by sol-gel impregnation method. Three effective parameters were optimized using Taguchi method, consisted of: (i) atomic ratios of Fe to Ti; (ii) sintering temperature; (iii) sintering time. The characterization of samples was determined using X-ray diffraction, BET- specific surface area, UV- Vis reflectance spectra (DRS) and scanning electron microscope (SEM). The XRD patterns of the samples indicated the existence of anatase crystal phase in structure. UV- Vis reflectance spectra showed an enhancement in light absorbance in the visible region (wavelength > 400 nm) for iron-doped samples. The photocatalytic activity of samples was investigated by the degradation of RO 16 (RO 16) dye under UV irradiation. The results illustrated that the photocatalytic activity of iron-doped TiO2 was more than pure TiO2, because of the smaller crystal size, grater BET surface area and higher light absorption ability.

  13. 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.

  14. Enhanced electron lifetime on nitrogen-doped TiO2 films for dye-sensitized solar cells.

    PubMed

    Yun, Tae Kwan; Cheon, Jong Hun; Bae, Jae Young; Ahn, Kwang-Soon; Kim, Jae Hong

    2012-04-01

    Nitrogen-doped TiO2 crystallites were prepared via the hydrolysis of TiCl4 using an ammonia medium in an aqueous solution for DSSC photoelectrodes. The optimized photoelectrode for the DSSC was prepared with 9.4 nm sized N-doped TiO2 crystal (BET; 200 m2/g), which provides a relatively high short circuit current and energy conversion efficiency in the DSSC. The photovoltaic performance of the N-doped TiO2 electrode was confirmed using incident photon-to-current efficient spectra, impedance analyses, and Bode-phase plots which proved that the N-doped TiO2 electrode has a significantly enhanced electron lifetime compared with that of the P25 electrode.

  15. Mesoporous nitrogen-doped TiO2 sphere applied for quasi-solid-state dye-sensitized solar cell.

    PubMed

    Xiang, Peng; Li, Xiong; Wang, Heng; Liu, Guanghui; Shu, Ting; Zhou, Ziming; Ku, Zhiliang; Rong, Yaoguang; Xu, Mi; Liu, Linfeng; Hu, Min; Yang, Ying; Chen, Wei; Liu, Tongfa; Zhang, Meili; Han, Hongwei

    2011-11-24

    A mesoscopic nitrogen-doped TiO2 sphere has been developed for a quasi-solid-state dye-sensitized solar cell [DSSC]. Compared with the undoped TiO2 sphere, the quasi-solid-state DSSC based on the nitrogen-doped TiO2 sphere shows more excellent photovoltaic performance. The photoelectrochemistry of electrodes based on nitrogen-doped and undoped TiO2 spheres was characterized with Mott-Schottky analysis, intensity modulated photocurrent spectroscopy, and electrochemical impedance spectroscopy, which indicated that both the quasi-Fermi level and the charge transport of the photoelectrode were improved after being doped with nitrogen. As a result, a photoelectric conversion efficiency of 6.01% was obtained for the quasi-solid-state DSSC.

  16. 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.

  17. Design of multi-porous layer for dye-sensitized solar cells by doping with TiO2 nanoparticles.

    PubMed

    Hsieh, Tung-Li; Chu, Ann-Kuo; Huang, Wen-Yao

    2013-01-01

    We propose a multi-layer dye-sensitized solar cell (DSSC). Conventional DSSC components use a singular TiO2 particle size and a mono-layer active layer, but we demonstrate a multi-layer and multi-scale TiO2 particle based DSSC. Doping with large TiO2 particles can produce light scattering inside the DSSC component. Light scattering effects reduce TiO2 absorption at wavelengths of 200-300 nm. The unabsorbed light zig-zags between the Pt back electrode layer and the substrate, and enhances the Ru-dye absorption. To enhance the scattering, we doped the active layer with 20 wt% of large diameter TiO2. The multi-layer DSSC increases efficiency by about 15% compared with standard DSSCs.

  18. Heterogeneous photocatalytic decomposition of benzene on lanthanum-doped TiO2 film at ambient temperature.

    PubMed

    Zhang, Shicheng; Zheng, Zhijian; Wang, Jinhe; Chen, Jianmin

    2006-12-01

    Lanthanum-doped anatase TiO2 thin films on glass prepared via a sol-gel process have been shown to have much higher photocatalytic activity for the degradation of gaseous benzene than pure anatase TiO2 thin film. The photodecomposition of benzene on both types of TiO2 films follows the first-order kinetics while the CO(2) and CO formation followed the zero-order kinetics. GC/MS identification of the intermediates produced during the photodegradation of benzene revealed that doping lanthanum into TiO2 thin film favors a cleavage of benzene ring. An optimal lanthanum amount with respect to photocatalytic activity was about 2.5 wt% (La2O3/TiO2).

  19. Phosphorus Cation Doping: A New Strategy for Boosting Photoelectrochemical Performance on TiO2 Nanotube Photonic Crystals.

    PubMed

    Li, Zhenzhen; Xin, Yanmei; Wu, Wenlong; Fu, Baihe; Zhang, Zhonghai

    2016-11-16

    Photoelectrochemical (PEC) water splitting is a promising technique for sustainable hydrogen generation. However, PEC performance on current semiconductors needs further improvement. Herein, a phosphorus cation doping strategy is proposed to fundamentally boost PEC performance on TiO2 nanotube photonic crystal (TiO2 NTPC) photoelectrodes in both the visible-light region and full solar-light illumination. The self-supported P-TiO2 NTPC photoelectrodes are fabricated by a facile two-step electrochemical anodization method and subsequent phosphidation treatment. The Ti(4+) is partially replaced by P cations (P(5+)) from the crystal lattice, which narrows the band gap of TiO2 and induces charge imbalance by the formation of Ti-O-P bonds. We believe the combination of unique photonic nanostructures of TiO2 NTPCs and P cation doping strategy will open up a new opportunity for enhancing PEC performance of TiO2-based photoelectrodes.

  20. Electrospun nanofibers of Bi-doped TiO2 with high photocatalytic activity under visible light irradiation.

    PubMed

    Xu, Jie; Wang, Wenzhong; Shang, Meng; Gao, Erping; Zhang, Zhijie; Ren, Jia

    2011-11-30

    Bi-doped TiO(2) nanofibers with different Bi content were firstly prepared by an electrospinning method. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectra (PL), and UV-vis diffuse reflectance spectroscopy (DRS). The results indicated that Bi(3+) ions were successfully incorporated into TiO(2) and extended the absorption of TiO(2) into visible light region. The photocatalytic experiments showed that Bi-doped TiO(2) nanofibers exhibited higher activities than sole TiO(2) in the degradation of rhodamine B (RhB) and phenol under visible light irradiation (λ>420 nm), and 3% Bi:TiO(2) samples showed the highest photocatalytic activities.

  1. Enhanced visible-light photocatalytic performances of Ag3PO4 surface-modified with small amounts of TiO2 and Ag

    NASA Astrophysics Data System (ADS)

    Wang, Desong; Li, Lei; Luo, Qingzhi; An, Jing; Li, Xueyan; Yin, Rong; Zhao, Mangmang

    2014-12-01

    A novel approach has been developed to prepare an efficient visible-light photocatalyst using Ag3PO4 and TiO2 sol as precursors. First, Ag3PO4 particles were dipped into TiO2 sol for 5 min and were filtered quickly. Second, Ag3PO4 particles adsorbing a small amount of TiO2 sol were aged for 24 h to form TiO2 gel on their surface. Finally, Ag3PO4 particles covered by TiO2 gel were calcined at 450 °C for 2 h to obtain the surface-modified Ag3PO4 sample. The surface-modified Ag3PO4 was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The visible-light photocatalytic performances of the surface-modified Ag3PO4 were evaluated by the photodegradation of methyl orange or phenol solution. The results showed that the surface-modified Ag3PO4 exhibited much higher visible-light photocatalytic activity and stability than pure Ag3PO4. As the amount of TiO2 gel on the Ag3PO4 surface increased, the visible-light photocatalytic activity increased first and then decreased. The surface-modification of Ag3PO4 obviously decreased its solubility in water environment due to the protection of TiO2 and Ag nanocrystals on the surface. The visible-light photocatalytic mechanism of the surface-modified Ag3PO4 has been discussed.

  2. The preparation of nitrogen-doped TiO 2- xN x photocatalyst coated on hollow glass microbeads

    NASA Astrophysics Data System (ADS)

    Shifu, Chen; Xuqiang, Liu; Yunzhang, Liu; Gengyu, Cao

    2007-01-01

    In this paper, the effective method for nitrogen-doped TiO 2- xN x photocatalyst coated on hollow glass microbeads is described, which uses titanium tetraisopropoxide [Ti( iso-OC 3H 7) 4] as the raw materials and gaseous ammonia as a heat treatment atmosphere. The effects of heat treatment temperature and time on the photocatalytic activity of TiO 2- xN x/beads are studied. The photocatalyst is characterized by the UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis and scanning electron microscopy (SEM). The results show that when the TiO 2- xN x/beads is heated at 650 °C for 5 h, the photocatalytic activity of the TiO 2- xN x/beads is the best. Compared with TiO 2, the photoabsorption wavelength range of nitrogen-doped TiO 2- xN x red shifts of about 60 nm, and the photoabsorption intensity increases as well. The photocatalytic activity of the TiO 2- xN x/beads is higher than that of the TiO 2/beads under visible light irradiation. The presence of nitrogen neither influences on the transformation of anatase to rutile, nor creates new crystal phases. When the TiO 2- xN x/beads is heated at 650 °C for 5 h, the amount of nitrogen-doped is 0.53 wt.% in the TiO 2- xN x. As the density of TiO 2- xN x/beads prepared is lower than 1.0 g/cm 3, it may float on water surface and use broader sunlight spectrum directly.

  3. 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.

  4. Ag-decorated TiO2 photocatalytic membrane with hierarchical architecture: photocatalytic and anti-bacterial activities.

    PubMed

    Goei, Ronn; Lim, Teik-Thye

    2014-08-01

    Ag-decorated TiO2 (Ag-TiO2) photocatalytic membranes have been fabricated by using Pluronic P-123 as a pore-forming and structure-directing agent. Six different hierarchical architectures were obtained by multilayer coating of different Ag-TiO2 sols. The porous structure of the resulting layers could be fine-tuned by altering the amounts of P-123 and AgNO3 added during the preparation of TiO2 sols. Physico-chemical and morphological properties of different Ag-TiO2 layers were thoroughly investigated. Ag nanoparticles were successfully incorporated into the TiO2 matrix. The Ag-TiO2 membranes possessed multi-functionality of membrane retention, Ag-enhanced TiO2 photocatalytic activity and anti-bacterial action. They were evaluated through experiments using a batch reactor and a photocatalytic membrane reactor (PMR). The best performing membrane was able to remove up to 1007 mg m(-2) h(-1) of Rhodamine B in the PMR. Two phenomena (photocatalytic degradation and adsorptive-membrane retention) that were responsible for the RhB removal were evaluated. In the batch reactor operated in dark, the membranes were able to remove greater than 5-logs of Escherichia coli. The membrane with the highest percentage of Ag incorporated was able to remove close to 7-logs of E. coli when operated in the PMR.

  5. Preparation and Characterization of Rutile-Type TiO2 Doped with Cu

    NASA Astrophysics Data System (ADS)

    Tryba, B.; Orlikowski, J.; Wróbel, R. J.; Przepiórski, J.; Morawski, A. W.

    2015-03-01

    Visible-light active photocatalysts were prepared by doping Cu-TiO2 through the sol-gel method. The influence of the preparation conditions such as pH of sol-gel solution and calcination temperature on the properties of TiO2-Cu was investigated. The presence of Cu caused reduction of band-gap energy, which was more visible in the rutile-type TiO2. Low pH of sol-gel solution such as pH 1.5 favorized formation of rutile during calcination and caused slower growth of the crystallites with increasing temperature of calcination in comparison with sol-gel prepared at pH 3. XPS measurements showed that Cu was placed mostly on the surface of TiO2. For sample calcined at 600 °C, the surface concentration of copper was 1.1 wt.%. The presence of both, rutile phase and Cu, increased adsorption of phenol and facilitated its photocatalytic decomposition. Moreover, reduced band-gap energy in rutile-type TiO2-Cu photocatalyst enabled phenol decomposition under visible light.

  6. 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.

  7. 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.

  8. Ferromagnetism at room temperature with a large magnetic moment in anatase V-doped TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Hong, Nguyen Hoa; Sakai, Joe; Hassini, Awatef

    2004-04-01

    V-doped TiO2 thin films were grown by laser ablation on LaAlO3 substrates. In the chosen range of the growth conditions, all V:TiO2 films have an anatase structure and exhibit semiconducting and ferromagnetic behaviors at room temperature. V:TiO2 films have a giant magnetic moment and they seem to be far better ferromagnetic than Co/Fe/Ni-doped TiO2 films. This study has proved that a few percent of V substituting for Ti in TiO2 can result in a potential diluted magnetic semiconductor.

  9. Synthesis and electrorheological effect of Cr doped TiO2 nanorods with nanocavities in silicone oil suspensions

    NASA Astrophysics Data System (ADS)

    Almajdalawi, S.; Pavlinek, V.; Mrlik, M.; Cheng, Q.; Sedlacik, M.

    2013-02-01

    Titanium dioxide (TiO2) nanorods with nanocavities doped with chromium (Cr) were synthesized by hydrothermal method. The morphology of prepared nanorods was determined by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The electrorheological (ER) behaviour of suspensions based on TiO2 was investigated under the steady shear, and the yield stress was chosen as a suitable tool for a comparison of ER performance. Some optimum in level of Cr doping of TiO2 was found.

  10. 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.

  11. 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

  12. [Preparation, characterization of Si doped TiO2 nanotubes and its application in photocatalytic oxidation of VOCs].

    PubMed

    Zou, Xue-Jun; Li, Xin-Yong; Qu, Zhen-Ping; Wang, Jiang-Jiang

    2011-12-01

    The Si-doped TiO2 nanotubes photocatalysts was synthesized by anodic oxidation method, which used Na2SiF6/HF as an electrolyte, and was characterized by means of SEM, XRD, DRS and EDX. TiO2 nanotubes composed of anatase phase and rutile phase, and Si was highly dispersed on the wall of TiO2 nanotubes. The photocatalytic activity of the Si-doped TiO2 nanotubes was investigated for photocatalytic degradation of gaseous toluene. It was found that the photocatalytic activity of Si-doped TiO2 nanotubes, which prepared by 0.03 mol x L x (-1) Na2SiF6/HF and calcined at 400 degrees C for 1 h, was the highest. The conversion of toluene was 60% over the prepared Si doped TiO2 nanotubes under UV light, which was one times higher than that of pure TiO2 nanotubes.

  13. 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.

  14. Effect of UV irradiation on wear protection of TiO2 and Ni-doped TiO2 coatings

    NASA Astrophysics Data System (ADS)

    Wan, Yong; Sun, Baojian; Xu, Zhen; Chao, Wenliu

    2012-03-01

    The relationship between UV photoinduced hydrophilicity and tribological performance of the thin films of pure and Ni-doped TiO2 was investigated in this paper. The films were prepared on a glass substrate by sol-gel and spin coating process from specially formulated ethanol sols. The chemical structure and morphologies of the films surface were observed with X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD) and atomic force microscope (AFM). The tribological properties of obtained thin films, when sliding against steel ball, were evaluated on a one-way reciprocating friction tester. It is clearly observed that UV irradiation resume the hydrophobicility of the films of pure and Ni-doped TiO2, however greatly worsen their wear protection properties.

  15. 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.

  16. 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.

  17. Effective nitrogen doping into TiO2 (N-TiO2) for visible light response photocatalysis.

    PubMed

    Yoshida, Tomoko; Niimi, Satoshi; Yamamoto, Muneaki; Nomoto, Toyokazu; Yagi, Shinya

    2015-06-01

    The thickness-controlled TiO2 thin films are fabricated by the pulsed laser deposition (PLD) method. These samples function as photocatalysts under UV light irradiation and the reaction rate depends on the TiO2 thickness, i.e., with an increase of thickness, it increases to the maximum, followed by decreasing to be constant. Such variation of the reaction rate is fundamentally explained by the competitive production and annihilation processes of photogenerated electrons and holes in TiO2 films, and the optimum TiO2 thickness is estimated to be ca. 10nm. We also tried to dope nitrogen into the effective depth region (ca. 10nm) of TiO2 by an ion implantation technique. The nitrogen doped TiO2 enhanced photocatalytic activity under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1⩽x⩽2) species. In the valence band XPS spectrum of the high active sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substituting nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts.

  18. 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

  19. 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.

  20. 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.

  1. A Pt-doped TiO2 nanotube arrays sensor for detecting SF6 decomposition products.

    PubMed

    Zhang, Xiaoxing; Tie, Jing; Zhang, Jinbin

    2013-10-30

    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.

  2. 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.

  3. Photocatalytic activity and characterization of sol-gel-derived Ni-doped TiO2-coated active carbon composites

    NASA Astrophysics Data System (ADS)

    Bhosale, R. R.; Pujari, S. R.; Lande, M. K.; Arbad, B. R.; Pawar, S. B.; Gambhire, A. B.

    2012-11-01

    Ni-doped, TiO2-coated active carbon (Ni-TiO2/AC) were prepared by a sol-gel method. The effect of supports, including TiO2 and active carbon (AC), on the molecular structure and photocatalytic activity of nickel oxide for complete decomposition of methylene blue has been examined with respect to the content of Ni on the catalyst surface. The photocatalytic activities of the Ni-TiO2/AC composites were evaluated in the decomposition of methylene blue solution under visible-light irradiation. The results indicate that Ni-TiO2/AC has a higher efficiency in decomposition of methylene blue than TiO2 and TiO2/AC. This was attributed to the different functions of active carbon and nickel species. First, nanosize TiO2 particles on composites were not reunited, possible because active carbon retards transformation of anatase into rutile and decrease the crystallite size. Second, production of high concentrations of organic compound near Ni-TiO2. Third, carbon in active carbon causes some of the TiO2 to reduce to Ti3+ ions, which prevents electron-hole pair recombination. It was found that the addition of Ni to TiO2 sol could suppress the grain growth of TiO2 crystals and increase the hydroxyl content on the surface of TiO2/AC. The photocatalytic efficiency and activity of the composites remained good, even after three cycles.

  4. Theoretical and experimental study on the electronic structure and optical absorption properties of P-doped TiO 2

    NASA Astrophysics Data System (ADS)

    Xu, Ling; Tang, Chao-Qun; Qian, Jun; Huang, Zong-Bin

    2010-02-01

    Phosphorus-doped nanosized TiO 2 powders were prepared by a sol-gel technology. The optical absorption studies revealed that the spectral responses of phosphorus-doped (P-doped) TiO 2 powders shift to the visible light region. The optimum phosphorus (P) content in our experiments is 16.7% (mol), and the corresponding absorption edge shifts to 450 nm. Furthermore, our ab initio calculations support the conclusion that the doping of phosphorus can reduce the band gap by mixing the P 3p states with O 2p states. The theoretical lattice parameters and optimum phosphorus content are in agreement with the experimental results.

  5. the effect of electron doping in TiO2 assessed by ARPES

    NASA Astrophysics Data System (ADS)

    Moreschini, Luca; Moser, Simon; Jacimovic, Jacim; Barisic, Osor; Berger, Helmut; Magrez, Arnaud; Chang, Young Jun; Kim, Keun Su; Bostwick, Aaron; Forro, Laszlo; Rotenberg, Eli; Grioni, Marco

    2013-03-01

    The titanium oxide TiO2 has been object of extensive studies because of its suitability in many practical fields, ranging from photovoltaic applications, to catalysis, memristors, and others. As for many other transition metal oxides, great attention has been devoted to the impact on the electronic structure of different doping mechanisms, either extrinsic or due to the creation of oxygen vacancies. Here we report an angle-resolved photoemission (ARPES) work on TiO2 single crystals and epitaxial films grown wIth the in situ pulsed-laser-deposition (PLD) system available on beamline 7.0.1 at the Advanced Light Source. We show the evolution of the electronic structure as a function of the amount of oxygen vacancies induced by the photon beam.

  6. Tuning the Fermi-level of TiO2 mesoporous layer by lanthanum doping towards efficient perovskite solar cells.

    PubMed

    Gao, Xiao-Xin; Ge, Qian-Qing; Xue, Ding-Jiang; Ding, Jie; Ma, Jing-Yuan; Chen, Yao-Xuan; Zhang, Bao; Feng, Yaqing; Wan, Li-Jun; Hu, Jin-Song

    2016-09-29

    Tuning the band alignment is proved to be an effective way to facilitate carrier transportation and thus enhance the power conversion efficiency (PCE) of solar cells. Doping the compact layer with metal ions or modifying the interfaces among functional layers in perovskite solar cells (PSCs) can appreciably improve the PCE of PSCs. Inspired by the rare earth elemental doping of TiO2, which has witnessed the success in photocatalysis and dye-sensitized solar cells, we firstly demonstrated here that La(3+) doping in the mesoporous TiO2 layer of a mesostructured PSC can tune its Fermi level and thus significantly enhance the device PCE. Systematic analysis reveals that doping La(3+) into TiO2 raises the Fermi level of TiO2 through scavenging oxygen and inducing vacancies, which subsequently increases the open circuit voltage and the fill factor while reducing the series resistance of the PSC using La(3+)-doped TiO2 as a mesoporous layer. As a result, a PCE of 15.42% is achieved, which is appreciably higher than the PCE of a device with undoped TiO2 (12.11%).

  7. 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.

  8. Self-doped TiO2-x nanowires with enhanced photocatalytic activity: Facile synthesis and effects of the Ti3+

    NASA Astrophysics Data System (ADS)

    Wang, Junpeng; Yang, Ping; Huang, Baibiao

    2015-11-01

    Synthesis of Ti3+ self-doped TiO2 with high stability is very necessary to understand the role of Ti3+ defects in photocatalytic process. In this study, we report a simple strategy for preparing stable Ti3+ self-doped TiO2 nanowires with Ti2O3 as precursors. Raman and XPS spectrum confirmed the existence of Ti3+ and oxygen vacancies. Compared with the pure TiO2, the photocatalytic activity of the Ti3+ self-doped TiO2 enhanced under UV light irradiation, however, neither pure TiO2 nor the self-dope TiO2 samples exhibit photocatalytic activity while irradiated under visible light, though the self-doped TiO2 have an enhanced absorption in visible region. On the basis of the experimental results, the possible mechanism of Ti3+ in photocatalytic process is proposed.

  9. 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

  10. 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.

  11. TiO2 nanoparticles doped SiO2 films with ordered mesopore channels: a catalytic nanoreactor.

    PubMed

    Saha, Jony; Mitra, Anuradha; Dandapat, Anirban; De, Goutam

    2014-04-07

    Titanium dioxide (TiO2) incorporated ordered 2D hexagonal mesoporous silica (SiO2) films on a glass substrate were fabricated for use as a catalytic nanoreactor. Films were prepared using a tetraethyl orthosilicate (TEOS) derived SiO2 sol and a commercially available dispersion of TiO2 nanoparticles (NPs) in the presence of pluronic P123 as the structure directing agent. The effect of TiO2 doping (4-10 mol% with respect to the equivalent SiO2) into the ordered mesoporous SiO2 matrix was thoroughly investigated. The undoped SiO2 film showed a mesostructural transformation after heat-treatment at 350 °C whereas incorporation of TiO2 restricted such a transformation. Among all the TiO2 incorporated films, TEM showed that the 7 equivalent mol% TiO2 doped SiO2 film (ST-7) had an optimal composition which could retain the more organized 2D hexagonal (space group p6mm)-like mesostructures after heat-treatment. The catalytic activities of the TiO2 doped (4-10 mol%) films were investigated for the reduction of toxic KMnO4 in an aqueous medium. ST-7 film showed the maximum catalytic activity, as well as reusability. A TEM study on the resultant solution after KMnO4 reduction revealed the formation of MnO2 nanowires. It was understood that the embedded TiO2 NPs bonded SiO2 matrix increased the surface hydroxyl groups of the composite films resulting in the generation of acidic sites. The catalytic process can be explained by this enhanced surface acidity. The mesoporous channel of the ST-7 films with TiO2 doping can be used as a nanoreactor to form extremely thin MnO2 nanowires.

  12. Enhanced dopant solubility and visible-light absorption in Cr-N co-doped TiO2 nanoclusters

    SciTech Connect

    Chiodi, Dr Mirco; Cheney, Christine; Vilmercati, Paolo; Cavaliere, Emanuele; Mannella, Norman; Gavioli, Luca; Weitering, Harm H

    2012-01-01

    A major obstacle toward employing TiO2 as an efficient photoactive material is related to its large optical band gap, strongly limiting visible light absorption. Substitutional doping with both donors and acceptors (co-doping) potentially leads to a significant band gap reduction, but the effectiveness of the co-doping approach remains limited by the low solubility of dopants inside TiO2. Here we show that nanostructured Cr and N co-doped TiO2 thin films can be obtained by Supersonic Cluster Beam Deposition (SCBD) with a high concentration of dopants and a strongly reduced band gap. Complementary spectroscopic investigations show that doping effectively occurs into substitutional lattice sites, inducing dopant levels in the gap that are remarkably delocalized. The high surface-to-volume ratio, typical of SCBD nanostructured films, likely facilitates the dopant incorporation. The present results indicate that SCBD films are highly promising photoactive nanophase materials.

  13. Synthesis of Ag-decorated porous TiO2 nanowires through a sunlight induced reduction method and its enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Yao, Yun-Chang; Dai, Xin-Rong; Hu, Xiao-Ye; Huang, Su-Zhen; Jin, Zhen

    2016-11-01

    In this work, Ag-decorated porous TiO2 nanowires were successfully synthesized via a facile and low-cost sunlight induced reduction method. The cooperation of sunlight irradiation and ethanol reduction results the formation and decoration of the Ag nanoparticles on the porous TiO2 nanowires. The structure of the Ag-decorated porous TiO2 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Energy dispersive spectroscopy (EDS) measurements. It can be seen that the Ag nanoparticles are well dispersed within the porous TiO2 nanowires. The as-prepared Ag-decorated porous TiO2 nanowires exhibits excellent photocatalytic properties. The photocatalytic tests show that 10 ppm methylene blue can be photodegraded within 60 min. And the photodegradation ratio of the Ag-decorated porous TiO2 nanowires much higher than that of P25 and porous TiO2 nanowires. Moreover, the Ag-decorated porous TiO2 nanowires also reveal good photocatalytic activity towards to other organic pollutions, such as phenol and R6G. Therefore, it is believed that the Ag-decorated porous TiO2 nanowires can be used as a potential high performance photocatalyst in wastewater treatment.

  14. Enhancing Efficiency and Stability of Perovskite Solar Cells through Nb-Doping of TiO2 at Low Temperature.

    PubMed

    Yin, Guannan; Ma, Jiaxin; Jiang, Hong; Li, Juan; Yang, Dong; Gao, Fei; Zeng, Jinghui; Liu, Zhike; Liu, Shengzhong Frank

    2017-03-29

    The conduction band energy, conductivity, mobility, and electronic trap states of electron transport layer (ETL) are very important to the efficiency and stability of a planar perovskite solar cell (PSC). However, as the most widely used ETL, TiO2 often needs to be prepared under high temperature and has unfavorable electrical properties such as low conductivity and high electronic trap states. Modifications such as elemental doping are effective methods for improving the electrical properties of TiO2 and the performance of PSCs. In this study, Nb-doped TiO2 films are prepared by a facile one-port chemical bath process at low temperature (70 °C) and applied as a high quality ETL for planar PSCs. Compared with pure TiO2, the Nb-doped TiO2 is more efficient for photogenerated electron injection and extraction, showing higher conductivity, higher mobility, and lower trap-state density. A PSC with 1% Nb-doped TiO2 yielded a power conversion efficiency of more than 19%, with about 90% of its initial efficiency remaining after storing for 1200 h in air or annealing at 80 °C for 20 h in a glovebox.

  15. Carbon coating stabilized Ti(3+)-doped TiO2 for photocatalytic hydrogen generation under visible light irradiation.

    PubMed

    Fu, Gao; Zhou, Peng; Zhao, Meiming; Zhu, Weidong; Yan, Shicheng; Yu, Tao; Zou, Zhigang

    2015-07-28

    Self-doping by Ti(3+) is a useful method to expand the light response of TiO2 into the visible light region. However, to obtain a stable Ti(3+)-doped TiO2 seems to be a challenge due to the easy oxidation of Ti(3+) during the heterogeneous reaction. Here, we propose a simple carbon coating route to stabilize the Ti(3+)-doped TiO2, in which both the Ti(3+) and precursor of the carbon coating layer were in situ formed from the hydrothermal hydrolysis of titanium isopropoxide. The carbon coated Ti(3+)-doped TiO2 exhibited excellent stability for photocatalytic hydrogen production. Based on electron paramagnetic resonance (EPR) analysis, the proposed stabilizing mechanism is that the conductive carbon coating layer as a barrier layer prevents the H2O and O2 from diffusing into the surface of the photocatalyst, which can oxidize the surface O vacancies and Ti(3+) in TiO2. Our findings offer a simple route to prepare a highly stable TiO2-based photocatalyst with visible light response.

  16. 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.

  17. Ge4+ doped TiO2 for stoichiometric degradation of warfare agents.

    PubMed

    Stengl, Václav; Grygar, Tomáš Matys; Opluštil, František; Němec, Tomáš

    2012-08-15

    Germanium doped TiO(2) was prepared by homogeneous hydrolysis of aqueous solutions of GeCl(4) and TiOSO(4) with urea. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, EDS analysis, specific surface area (BET) and porosity determination (BJH). Ge(4+) doping increases surface area and content of amorphous phase in prepared samples. These oxides were used in an experimental evaluation of their reactivity with chemical warfare agent, sulphur mustard, soman and agent VX. Ge(4+) doping worsens sulphur mustard degradation and improves soman and agent VX degradation. The best degree of removal (degradation), 100% of soman, 99% of agent VX and 95% of sulphur mustard, is achieved with sample with 2 wt.% of germanium.

  18. 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.

  19. 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

    2014-05-02

    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.

  20. 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

  1. Improved Wetting Characteristics in TiO2–Modified Ag-CuO Air Braze Filler Metals

    SciTech Connect

    Weil, K. Scott; Kim, Jin Yong Y.; Hardy, John S.; Darsell, Jens T.

    2006-01-01

    In this paper we report on the results of a series of sessile drop experiments designed to examine the effect of TiO2 on the wetting behavior of Ag-CuO air braze filler metals. It was found that TiO2 concentrations as small as 0.5 mol% can significantly decrease the contact angle of Ag-CuO on alumina over a compositional range of 1 – 34mol% CuO. The effect appears to maximize at a copper oxide concentration of ~4 mol% CuO regardless of the titania content.

  2. 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.

  3. Highly active Ag clusters stabilized on TiO2 nanocrystals for catalytic reduction of p-nitrophenol

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Zhao, Zhe; Ou, Dingrong; Tu, Baofeng; Cui, Daan; Wei, Xuming; Cheng, Mojie

    2016-11-01

    Ag/TiO2 nanocomposites comprising of Ag clusters on TiO2 nanocrystal surfaces are of great significance in catalysts and advanced functional materials. Herein a novel method to synthesize Ag/TiO2 nanocomposites with Ag clusters under 2 nm on TiO2 nanocrystal surfaces have been developed. The success of this method relies on a silver mirror reaction in toluene, which refers to the reduction of silver-dodecylamine complexes by acetaldehyde in the presence of mono-dispersed TiO2 nanocrystals. The prepared Ag/TiO2 nanocomposites have been characterized by FT-IR spectra, UV-vis absorption spectra, X-ray diffraction (XRD) analysis, ultra high resolution scanning electron microscope (Ultra-HRSEM), high resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectra (XPS). Catalytic activity of Ag/TiO2 nanocomposites is evaluated for the reduction of p-nitrophenol (4-NP) into p-aminophenol (4-AP) by NaBH4. Results demonstrate that Ag/TiO2 nanocomposites have shown an outstanding catalytic activity as well as a good stability in successive reduction of 4-NP. Noticeably, TOF of Ag/TiO2-0.75 nanocomposites obtained in this work is the highest among Ag based catalysts previously reported.

  4. FTIR spectra and thermal properties of TiO2-doped iron phosphate glasses

    NASA Astrophysics Data System (ADS)

    Lu, Mingwei; Wang, Fu; Liao, Qilong; Chen, Kuiru; Qin, Jianfa; Pan, Sheqi

    2015-02-01

    Structure and thermal properties of xTiO2·(90 - x) (60P2O5-40Fe2O3)ṡ10CaF2 (x = 0, 5, 10, 15, 20 and 25 mol%) glasses are investigated in detail by Fourier Transform Infrared Spectrum (FTIR) and Differential Thermal Analysis (DTA), respectively. It is found that incorporation of TiO2 increase the density and glass transition temperature of iron phosphate system glass. The increment of doped-TiO2 can also strengthen phosphate network chains due to increasing O/P ratios and more orthophosphate (Q0) units formed in the glass structure at expense of pyrophosphate (Q1) units and metaphosphate (Q2) groups. Moreover, the structure of iron phosphate glass with TiO2 content contain distorted octahedral [TiO6] linked to phosphate unit through Psbnd Osbnd Ti bonds, thus enhanced structure cohesion and increased density obtained. The knowledge provides an improved understanding of the role of TiO2 in the structure of iron phosphate glasses.

  5. Theoretical investigations of Ni- and Cu-doped TiO2

    NASA Astrophysics Data System (ADS)

    Esakki muthuraju, M.; Mahesh, R.; Sreekanth, T.; Venugopal Reddy, P.

    2014-03-01

    The electronic, magnetic and optical properties of rutile Ti1-xTMxO2 (where TM: Ni, Cu and x = 0.25) have been investigated by the density functional theory with the plane wave self consistent field method. For the calculation of exchange correlation potential, the local density approximation along with Hubbard correction (LDA +U) was used. Electronic, magnetic and optical properties were calculated using 12 atoms supercell of rutile TiO2 with one Ti atom replaced by a dopant transition metal atom. The band structure of doped rutile phase indicates the reduction of band gap leading to improvement in the photocatalytic properties of TiO2 as well as enhancement in its magnetic properties. The observed magnetism is explained on the basis of spin polarization of d states of Ti with dopants. Optical calculations by full potential, linear augmented plane wave plus local orbital (FP-LAPW+lo) method with ELK code established the presence of optical transitions in the visible light region. These theoretical calculations gave a meaningful information and excellent prediction to develop TiO2 for spintronics applications and photocatalytic applications in the visible region.

  6. Effective passivation of Ag nanowire-based flexible transparent conducting electrode by TiO2 nanoshell

    NASA Astrophysics Data System (ADS)

    Lee, Dong Geon; Lee, Dongjun; Yoo, Jin Sun; Lee, Sangwook; Jung, Hyun Suk

    2016-08-01

    Silver nanowire-based flexible transparent electrodes have critical problem, in spite of their excellent electrical and optical properties, that the electrical conductance and transparency degrade within several days in air because of oxidation of silver. To prevent the degradation of the silver nanowire, we encapsulated Ag-NWs with thin TiO2 barrier. Bar-coated silver nanowires on flexible polymer substrate were laminated at 120 °C, followed by atomic layer deposition of TiO2 nanoshell. With 20 nm of TiO2 nanoshells on silver nanowires, the transparent electrode keeps its electrical and optical properties over 2 months. Moreover, the TiO2-encapsulated silver nanowire-based transparent electrodes exhibit excellent bending durability.

  7. 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.

  8. The preparation of Zn2+-doped TiO(2) nanoparticles by sol-gel and solid phase reaction methods respectively and their photocatalytic activities.

    PubMed

    Liu, Guoguang; Zhang, Xuezhi; Xu, Yajie; Niu, Xinshu; Zheng, Liqing; Ding, Xuejun

    2005-06-01

    The photocatalytic oxidation of the organic pollutants with TiO(2) as photocatalyst has been widely studied in the world, and many achievements have been made. The degradation of pollutants is highly related to the photocatalytic activity of TiO(2). It is demonstrated that doping ions to TiO(2) is one way to enhance the photocatalytic activity of TiO(2). In this paper, Zn(2+)-doped TiO(2) nanoparticles were prepared through sol-gel and solid phase reaction methods, characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of the elaborated powders was studied following the degradation of Rhodamine B. The results showed that the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by sol-gel method is close to that of pure TiO(2) particles, however, the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by solid phase reaction method is much higher than that of pure TiO(2) particles. The most efficient degradation of Rhodamine B was found with TiO(2) particles doped with 0.5% Zn(2+) in mole and calcined at 500 degrees C. Also the reason for the enhancement of the photocatalytic activity of TiO(2) by Zn(2+) doping through solid phase reaction method was discussed.

  9. Effect of W doping level on TiO2 on the photocatalytic degradation of Diuron.

    PubMed

    Foura, Ghania; Soualah, Ahcène; Robert, Didier

    2017-01-01

    In the present study, three compositions of W-doped titania nano-photocatalyst are synthesized via the sol-gel method. The powders obtained were characterized by X-ray diffraction, Raman spectroscopy and UV-visible diffuse reflectance spectroscopy. The photocatalytic performances of the different photocatalysts are tested with respect to the degradation of Diuron in water solutions under simulated solar light and visible light irradiation. The W0.03Ti0.97O2 catalyst exhibits better photoactivity than the pure TiO2 even under simulated solar light and visible light. This improvement in activity was attributed to photoelectron/hole separation efficiency.

  10. Absence of ferromagnetism in Fe-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Balcells, Ll.; Frontera, C.; Sandiumenge, F.; Roig, A.; Martínez, B.; Kouam, J.; Monty, C.

    2006-09-01

    The structural and magnetic properties of Ti1-xFexO2-ɛ (x≈0.13) nanoparticles prepared by vaporization-condensation method are analyzed. Samples, mainly of rutile phase, exhibit a pronounced mosaic structure and are free of secondary phases or impurities. Mössbauer spectroscopy evidences the absence of magnetic ordering and shows features indicative of the existence of two doublets assigned to two different structural arrangements of Fe3+ ions substituting for Ti4+ ions in the rutile structure. The application of the Goodenough-Kanamori rules clearly indicates that conventional FM ordering should not be expected in Fe-doped TiO2 with rutile structure.

  11. Ta-doped Anatase TiO2 Epitaxial Film as Transparent Conducting Oxide

    NASA Astrophysics Data System (ADS)

    Hitosugi, Taro; Furubayashi, Yutaka; Ueda, Atsuki; Itabashi, Kinnosuke; Inaba, Kazuhisa; Hirose, Yasushi; Kinoda, Go; Yamamoto, Yukio; Shimada, Toshihiro; Hasegawa, Tetsuya

    2005-08-01

    We present electrical transport and optical properties of Ta-doped TiO2 epitaxial thin films with varying Ta concentration grown by the pulsed laser deposition method. The Ti0.95Ta0.05O2 film exhibited a resistivity of 2.5× 10-4 Ω cm at room temperature, and an internal transmittance of 95% in the visible light region. These values are comparable to those of a widely used transparent conducting oxide (TCO), indium tin oxide. Furthermore, this new material falls into a new category of TCOs that utilizes d electrons.

  12. TiO2 coated Au/Ag nanorods with enhanced photocatalytic activity under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Zhou, Na; Polavarapu, Lakshminarayana; Gao, Nengyue; Pan, Yanlin; Yuan, Peiyan; Wang, Qing; Xu, Qing-Hua

    2013-05-01

    A facile method was used to prepare uniform Au NR/TiO2 and Au/Ag NR/TiO2 core-shell composite nanoparticles. Au/Ag NR/TiO2 nanoparticles were found to display significantly enhanced visible light photo-catalytic activity compared to Au NR/TiO2 and the commercially available TiO2 nanoparticles. The enhancement mechanism was ascribed to injection of hot electrons of photo-excited Au/Ag NRs to TiO2, which was confirmed by 633 nm laser induced reduction of silver ions on the surface of Au/Ag NR/TiO2 composite nanoparticles.A facile method was used to prepare uniform Au NR/TiO2 and Au/Ag NR/TiO2 core-shell composite nanoparticles. Au/Ag NR/TiO2 nanoparticles were found to display significantly enhanced visible light photo-catalytic activity compared to Au NR/TiO2 and the commercially available TiO2 nanoparticles. The enhancement mechanism was ascribed to injection of hot electrons of photo-excited Au/Ag NRs to TiO2, which was confirmed by 633 nm laser induced reduction of silver ions on the surface of Au/Ag NR/TiO2 composite nanoparticles. Electronic supplementary information (ESI) available: The details of experimental procedures, SEM and TEM images of various nanoparticles prepared, photographs of the samples, control experiments, reusability test, wavelength dependent photocatalytic activities of Au/Ag/TiO2 nanoparticles, and UV-Vis spectra of a Ag nanoparticle formed on the surface of Au/Ag/TiO2 under visible light irradiation. See DOI: 10.1039/c3nr00517h

  13. 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.

  14. 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.

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

    PubMed

    Pelaez, Miguel; Baruwati, Babita; Varma, Rajender S; Luque, Rafael; Dionysiou, Dionysios D

    2013-10-03

    The performance of magnetically separable N-doped TiO2 was found to be significantly improved when compared with non-magnetic N-doped TiO2 for the removal of cyanotoxin microcystin-LR from aqueous medium. The observed enhanced photocatalytic activity may be related to the presence of ferrite nanoparticles in the composition of the magnetically separable composite N-doped TiO2.

  16. Methylene blue photocatalytic mineralization under visible irradiation on TiO2 thin films doped with chromium

    NASA Astrophysics Data System (ADS)

    Diaz-Uribe, Carlos; Vallejo, William; Ramos, Wilkendry

    2014-11-01

    We studied changes in structural, optical and photocatalytic properties of TiO2 thin films due to doping process with chromium. Powders of undoped TiO2 and chromium-doped TiO2 (Cr:TiO2) were synthesized by sol-gel method and, thin films were deposited by doctor blade method. The properties of the thin films were studied by X-ray diffraction (XRD), infrared spectroscopy (IR) and diffuse reflectance. The XRD patterns indicated that doping process changed the crystalline phases radio of TiO2 thin films, furthermore, the optical analysis showed that band gap value of Cr:TiO2 thin films was 31% fewer than undoped TiO2 thin films. Along, Langmuir-Hinshelwood model was used to obtain kinetic information of the photo-mineralization process; results indicated that photocatalytic activity of Cr:TiO2 thin films were four times better than undoped TiO2 thin films; finally the synergic effect was tested by addition of the H2O2, photocatalytic yield was improved from 26% to 61% when methylene blue photo-mineralization was assisted with slightly amount of H2O2.

  17. 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.

  18. 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

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

    PubMed

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-26

    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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    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.

  1. Degradation of microcystin-LR by highly efficient AgBr/Ag3PO4/TiO2 heterojunction photocatalyst under simulated solar light irradiation

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Utsumi, Motoo; Yang, Yingnan; Li, Dawei; Zhao, Yingxin; Zhang, Zhenya; Feng, Chuanping; Sugiura, Norio; Cheng, Jay Jiayang

    2015-01-01

    A novel photocatalyst AgBr/Ag3PO4/TiO2 was developed by a simple facile in situ deposition method and used for degradation of mirocystin-LR. TiO2 (P25) as a cost effective chemical was used to improve the stability of AgBr/Ag3PO4 under simulated solar light irradiation. The photocatalytic activity tests for this heterojunction were conducted under simulated solar light irradiation using methyl orange as targeted pollutant. The results indicated that the optimal Ag to Ti molar ratio for the photocatalytic activity of the resulting heterojunction AgBr/Ag3PO4/TiO2 was 1.5 (named as 1.5 BrPTi), which possessed higher photocatalytic capacity than AgBr/Ag3PO4. The 1.5 BrPTi heterojunction was also more stable than AgBr/Ag3PO4 in photocatalysis. This highly efficient and relatively stable photocatalyst was further tested for degradation of the hepatotoxin microcystin-LR (MC-LR). The results suggested that MC-LR was much more easily degraded by 1.5 BrPTi than by AgBr/Ag3PO4. The quenching effects of different scavengers proved that reactive h+ and •OH played important roles for MC-LR degradation.

  2. Electrodeposited Ag nanoparticles on TiO2 nanorods for enhanced UV visible light photoreduction CO2 to CH4

    NASA Astrophysics Data System (ADS)

    Kong, Dan; Tan, Jeannie Ziang Yie; Yang, Fei; Zeng, Jieliang; Zhang, Xiwen

    2013-07-01

    We employed the double-potentiostatic methodology to electrodeposit Ag nanoparticles on oriented single-crystalline rutile TiO2 nanorods synthesized by hydrothermal method. The synthesized composites were used as the photocatalyst to reduce CO2 to CH4 under UV irradiation, and tested by SEM, XRD, TEM, XPS, UV-vis and photoluminescence. Deposition with Ag nanoparticles was observed to enhance the photocatalytic activity (≈1.5-2.64 μmol (gcatal h)-1) up to 5 times with respect to undecorated TiO2 nanorods (≈0.5 μmol (gcatal h)-1). The increase in the CH4 yield was correlated with the surface morphology and structure of TiO2 nanorods.

  3. 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.

  4. Local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Tian-Xing; Feng, Ya-Juan; Huang, Jun-Heng; He, Jin-Fu; Liu, Qing-Hua; Pan, Zhi-Yun; Wu, Zi-Yu

    2015-02-01

    The local structures and optical absorption characteristics of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and ultraviolet-visible absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region. Supported by National Basic Research Program of China (2012CB825801), Science Fund for Creative Research Groups of NSFC (11321503), National Natural Science Foundation of China (11321503, 11179004) and Guangdong Natural Science Foundation (S2011040003985)

  5. Preparation, characterization and photocatalytic activity of manganese doped TiO(2) immobilized on silica gel.

    PubMed

    Xu, Yuehua; Lei, Bo; Guo, Laiqiu; Zhou, Wuyi; Liu, Youqin

    2008-12-15

    A series of Mn-TiO(2)/SiO(2) (silica gel loaded with manganese doped TiO(2)) photocatalysts have been prepared by sol-gel method, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities were enhanced in photocatalytic degradation of methyl orange over Mn-TiO(2)/SiO(2). XPS analysis shows that a Ti-O-Si or Ti-O-Mn bond is formed on the surface of photocatalyst. Mn is doped as a mixture of Mn(2+) and Mn(3+) on the surface of 1.0mol% Mn-TiO(2)/SiO(2). Mn(3+) appears to trap electrons and prohibit the electron-hole recombination. The electrons trapped in Mn(3+) site are subsequently transferred to the adsorbed O(2). As a result, the combination of the electron-hole pair was reduced.

  6. 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).

  7. Wavelength-sensitive photocatalytic degradation of methyl orange in aqueous suspension over iron(III)-doped TiO2 nanopowders under UV and visible light irradiation.

    PubMed

    Wang, X H; Li, J-G; Kamiyama, H; Moriyoshi, Y; Ishigaki, T

    2006-04-06

    Well-crystallized iron(III)-doped TiO2 nanopowders with controlled Fe3+ doping concentration and uniform dopant distribution, have been synthesized with plasma oxidative pyrolysis. The photocatalytic reactivity of the synthesized TiO2 nanopowders with a mean particle size of 50-70 nm was quantified in terms of the degradation rates of methyl orange (MO) in aqueous TiO2 suspension under UV (mainly 365 and 316 nm) and visible light irradiation (mainly 405 and 436 nm). The photodecomposition of MO over TiO2 nanopowders followed a distinct two-stage pseudo first order kinetics. Interestingly, the photocatalytic reactivity depends not only on the iron doping concentration but also on the wavelength of the irradiating light. Under UV irradiation, nominally undoped TiO2 had much higher reactivity than Fe3+ -doped TiO2, suggesting that Fe3+ doping (> 0.05 at. %) in TiO2 with a mean particle size of approximately 60 nm was detrimental to the photocatalytic decomposition of methyl orange. Whereas, under visible light irradiation, the Fe3+ -doped TiO2 with an intermediate iron doping concentration of approximately 1 at. % had the highest photocatalytic reactivity due to the narrowing of band gap so that it could effectively absorb the light with longer wavelength. A strategy for improving the photocatalytic reactivity of Fe3+ -doped TiO2 used in the visible light region is also proposed.

  8. Zn-doped nanocrystalline TiO2 films for CdS quantum dot sensitized solar cells.

    PubMed

    Zhu, Guang; Cheng, Zujun; Lv, Tian; Pan, Likun; Zhao, Qingfei; Sun, Zhuo

    2010-07-01

    Quantum dot-sensitized solar cells based on Zn-doped TiO(2) (Zn-TiO(2)) film photoanode and polysulfide electrolyte were fabricated. Zn-TiO(2) nanoparticles were obtained via a hydrothermal method and screen printed on the fluorine-doped tin oxide glass to prepare the photoanode. The structure, morphology and impedance of the Zn-TiO(2)/CdS film and the photovoltaic performance of the Zn-TiO(2)/CdS cell were investigated. It was found that the photovoltaic efficiency was improved by 24% when the Zn-TiO(2) film was adopted as the photoanode of CdS QDSSCs instead of only the TiO(2) layer. The improvement was ascribed to the reduction of electron recombination and the enhancement of electron transport in the TiO(2) film by Zn doping.

  9. 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.

  10. 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).

  11. Al-doped TiO2 mesoporous material supported Pd with enhanced catalytic activity for complete oxidation of ethanol

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Mu, Wentao; Su, Liqing; Li, Xingying; Guo, Yuyu; Zhang, Shen; Li, Zhe

    2017-04-01

    Pd catalysts supported on Al-doped TiO2 mesoporous materials were evaluated in complete oxidation of ethanol. The catalysts synthesized by wet impregnation based on evaporation-induced self-assembly were characterized by X-ray diffraction, measurement of pore structure, XPS, FT-IR, temperature programmed reduction and TEM. Characteristic results showed that the aluminium was doped into the lattice of mesoporous anatase TiO2 to form Al-O-Ti defect structure. Catalytic results revealed that Al-doped catalysts were much more active than the pristine one, especially at low temperature (≤200 °C). This should be ascribed to the introduction of aluminium ions that suppressed the strong metal-support interaction and increased the active sites of Pd oxides, enhanced the stabilized anatase TiO2, improved well dispersed high valence palladium species with high reducibility and enriched chemisorption oxygen.

  12. Non-metal doped TiO2 nanotube arrays for high efficiency photocatalytic decomposition of organic species in water

    NASA Astrophysics Data System (ADS)

    Szkoda, Mariusz; Siuzdak, Katarzyna; Lisowska-Oleksiak, Anna

    2016-10-01

    Titanium dioxide is a well-known photoactive semiconductor with a variety of possible applications. The procedure of pollutant degradation is mainly performed using TiO2 powder suspension. It can also be exploited an immobilized catalyst on a solid support. Morphology and chemical doping have a great influence on TiO2 activity under illumination. Here we compare photoactivity of titania nanotube arrays doped with non-metal atoms: nitrogen, iodine and boron applied for photodegradation of organic dye - methylene blue and terephtalic acid. The doped samples act as a much better photocatalyst in the degradation process of methylene blue and lead to the formation of much higher amount of hydroxyl radicals (•OH) than undoped TiO2 nanotube arrays. The use of a catalyst active under solar light illumination in the form of thin films on a stable substrate can be scaled up for an industrial application.

  13. Visible light induced electron transfer process over nitrogen doped TiO(2) nanocrystals prepared by oxidation of titanium nitride.

    PubMed

    Wu, Zhongbiao; Dong, Fan; Zhao, Weirong; Guo, Sen

    2008-08-30

    Nitrogen doped TiO(2) nanocrystals with anatase and rutile mixed phases were prepared by incomplete oxidation of titanium nitride at different temperatures. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), core level X-ray photoelectron spectroscopy (CL XPS), valence band X-ray photoelectron spectroscopy (VB XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and visible light excited photoluminescence (PL). The photocatalytic activity was evaluated for photocatalytic degradation of toluene in gas phase under visible light irradiation. The visible light absorption and photoactivities of these nitrogen doped TiO(2) nanocrystals can be clearly attributed to the change of the additional electronic (N(-)) states above the valence band of TiO(2) modified by N dopant as revealed by the VB XPS and visible light induced PL. A band gap structure model was established to explain the electron transfer process over nitrogen doped TiO(2) nanocrystals under visible light irradiation, which was consistent with the previous theoretical and experimental results. This model can also be applied to understand visible light induced photocatalysis over other nonmetal doped TiO(2).

  14. Band Gap Tailoring of TiO2 Nanowires by Nitrogen Doping Under N2/Ar Plasma Environment.

    PubMed

    Dhar, J C; Mondal, A; Bhattacharya, S; Singh, N K; Ngangbam, C; Chattopadhyay, K K

    2015-05-01

    Glancing angle deposited TiO2 nanowires (NWs) were doped with nitrogen (N) using plasma-enhanced chemical vapour deposition technique, under the treatment of N2/Ar plasma. A red shift (- 0.51 eV) in the main band transition and oxygen defect related transition (-2.1 eV) was observed for the N doped TiO2 nanowires. The interstitial nitrogen introduces mid-gap levels N (2P) above the O (2P) in the TiO2 forbidden gap. The photoluminescence measurement revealed a small red shift of -7 nm of anatase band gap from N doped TiO2 nanowires due to radiative recombination of carriers from conduction band to the N (2P) trap state. The low frequency Raman peaks at 304 cm(-1) (acoustical phonons with LA mode), 618 cm(-1) (optical phonons with LO modes) and the high frequency peak at 832 cm(-1) was observed from Ti-O-N due to the partial replacement of oxygen molecules by nitrogen into TiO2, during the doping process.

  15. Electrospun Nb-doped TiO2 nanofiber support for Pt nanoparticles with high electrocatalytic activity and durability.

    PubMed

    Kim, MinJoong; Kwon, ChoRong; Eom, KwangSup; Kim, JiHyun; Cho, EunAe

    2017-03-14

    This study explores a facile method to prepare an efficient and durable support for Pt catalyst of polymer electrolyte membrane fuel cell (PEMFC). As a candidate, Nb-doped TiO2 (Nb-TiO2) nanofibers are simply fabricated using an electrospinning technique, followed by a heat treatment. Doping Nb into the TiO2 nanofibers leads to a drastic increase in electrical conductivity with doping level of up to 25 at. % (Nb0.25Ti0.75O2). Pt nanoparticles are synthesized on the prepared 25 at. % Nb-doped TiO2-nanofibers (Pt/Nb-TiO2) as well as on a commercial powdered carbon black (Pt/C). The Pt/Nb-TiO2 nanofiber catalyst exhibits similar oxygen reaction reduction (ORR) activity to that of the Pt/C catalyst. However, during an accelerated stress test (AST), the Pt/Nb-TiO2 nanofiber catalyst retained more than 60% of the initial ORR activity while the Pt/C catalyst lost 65% of the initial activity. The excellent durability of the Pt/Nb-TiO2 nanofiber catalyst can be attributed to high corrosion resistance of TiO2 and strong interaction between Pt and TiO2.

  16. Linear and nonlinear optical studies of bare and copper doped TiO2 nanoparticles via sol gel technique.

    PubMed

    Rajamannan, B; Mugundan, S; Viruthagiri, G; Praveen, P; Shanmugam, N

    2014-01-24

    In general, the nanoparticles of TiO2 may exist in the phases of anatase, rutile and brookite. In the present work, we used titanium terta iso propoxide and 2-propanol as a common starting material to prepare the precursors of bare and copper doped nanosized TiO2. Then the synthesized products were calcinated at 500°C and after calcination the pure TiO2 nanoparticles in anatase phase were harvested. The crystallite sizes of bare and copper doped TiO2 nanoparticles were calculated from X-ray diffraction analysis. The existence of functional groups of the samples was identified by Fourier transform infrared spectroscopy. The optical properties of bare and doped samples were carried out using UV-DRS and photoluminescence measurements. The surface morphology and the element constitution of the copper doped TiO2 nanoparticles were studied by scanning electron microscope fitted with energy dispersive X-ray spectrometer arrangement. The nonlinear optical properties of the products were confirmed by Kurtz second harmonic generation (SHG) test and the output power generated by the nanoparticle was compared with that of potassium di hydrogen phosphate (KDP).

  17. Electrospun Nb-doped TiO2 nanofiber support for Pt nanoparticles with high electrocatalytic activity and durability

    PubMed Central

    Kim, MinJoong; Kwon, ChoRong; Eom, KwangSup; Kim, JiHyun; Cho, EunAe

    2017-01-01

    This study explores a facile method to prepare an efficient and durable support for Pt catalyst of polymer electrolyte membrane fuel cell (PEMFC). As a candidate, Nb-doped TiO2 (Nb-TiO2) nanofibers are simply fabricated using an electrospinning technique, followed by a heat treatment. Doping Nb into the TiO2 nanofibers leads to a drastic increase in electrical conductivity with doping level of up to 25 at. % (Nb0.25Ti0.75O2). Pt nanoparticles are synthesized on the prepared 25 at. % Nb-doped TiO2-nanofibers (Pt/Nb-TiO2) as well as on a commercial powdered carbon black (Pt/C). The Pt/Nb-TiO2 nanofiber catalyst exhibits similar oxygen reaction reduction (ORR) activity to that of the Pt/C catalyst. However, during an accelerated stress test (AST), the Pt/Nb-TiO2 nanofiber catalyst retained more than 60% of the initial ORR activity while the Pt/C catalyst lost 65% of the initial activity. The excellent durability of the Pt/Nb-TiO2 nanofiber catalyst can be attributed to high corrosion resistance of TiO2 and strong interaction between Pt and TiO2. PMID:28290503

  18. Electrospun Nb-doped TiO2 nanofiber support for Pt nanoparticles with high electrocatalytic activity and durability

    NASA Astrophysics Data System (ADS)

    Kim, Minjoong; Kwon, Chorong; Eom, Kwangsup; Kim, Jihyun; Cho, Eunae

    2017-03-01

    This study explores a facile method to prepare an efficient and durable support for Pt catalyst of polymer electrolyte membrane fuel cell (PEMFC). As a candidate, Nb-doped TiO2 (Nb-TiO2) nanofibers are simply fabricated using an electrospinning technique, followed by a heat treatment. Doping Nb into the TiO2 nanofibers leads to a drastic increase in electrical conductivity with doping level of up to 25 at. % (Nb0.25Ti0.75O2). Pt nanoparticles are synthesized on the prepared 25 at. % Nb-doped TiO2-nanofibers (Pt/Nb-TiO2) as well as on a commercial powdered carbon black (Pt/C). The Pt/Nb-TiO2 nanofiber catalyst exhibits similar oxygen reaction reduction (ORR) activity to that of the Pt/C catalyst. However, during an accelerated stress test (AST), the Pt/Nb-TiO2 nanofiber catalyst retained more than 60% of the initial ORR activity while the Pt/C catalyst lost 65% of the initial activity. The excellent durability of the Pt/Nb-TiO2 nanofiber catalyst can be attributed to high corrosion resistance of TiO2 and strong interaction between Pt and TiO2.

  19. Zr-doped TiO2 supported on delaminated clay materials for solar photocatalytic treatment of emerging pollutants.

    PubMed

    Belver, C; Bedia, J; Rodriguez, J J

    2017-01-15

    Solar light-active Zr-doped TiO2 nanoparticles were successfully immobilized on delaminated clay materials by a one-step sol-gel route. Fixing the amount of TiO2 at 65wt.%, this work studies the influence of Zr loading (up to 2%) on the photocatalytic activity of the resulting Zr-doped TiO2/clay materials. The structural characterization demonstrates that all samples were formed by a delaminated clay with nanostructured anatase assembled on its surface. The Zr dopant was successfully incorporated into the anatase lattice, resulting in a slight deformation of the anatase crystal and the reduction of the band gap. These materials exhibit high surface area with a disordered mesoporous structure formed by TiO2 particles (15-20nm) supported on a delaminated clay. They were tested in the solar photodegradation of antipyrine, usually used as an analgesic drug and selected as an example of emerging pollutant. High degradation rates have been obtained at low antipyrine concentrations and high solar irradiation intensities with the Zr-doped TiO2/clay catalyst, more effective than the undoped one. This work demonstrates the potential application of the synthesis method for preparing novel and efficient solar-light photocatalysts based on metal-doped anatase and a delaminated clay.

  20. TiO2 coated Au/Ag nanorods with enhanced photocatalytic activity under visible light irradiation.

    PubMed

    Zhou, Na; Polavarapu, Lakshminarayana; Gao, Nengyue; Pan, Yanlin; Yuan, Peiyan; Wang, Qing; Xu, Qing-Hua

    2013-05-21

    A facile method was used to prepare uniform Au NR/TiO2 and Au/Ag NR/TiO2 core-shell composite nanoparticles. Au/Ag NR/TiO2 nanoparticles were found to display significantly enhanced visible light photo-catalytic activity compared to Au NR/TiO2 and the commercially available TiO2 nanoparticles. The enhancement mechanism was ascribed to injection of hot electrons of photo-excited Au/Ag NRs to TiO2, which was confirmed by 633 nm laser induced reduction of silver ions on the surface of Au/Ag NR/TiO2 composite nanoparticles.

  1. 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.

  2. 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.

  3. Photoelectrocatalytic inactivation of fecal coliform bacteria in urban wastewater using nanoparticulated films of TiO2 and TiO2/Ag.

    PubMed

    Domínguez-Espíndola, Ruth Belinda; Varia, Jeet C; Álvarez-Gallegos, Alberto; Ortiz-Hernández, Ma Laura; Peña-Camacho, Justina Leticia; Silva-Martínez, Susana

    2017-03-01

    Photocatalysis has shown the ability to inactivate a wide range of harmful microorganisms with traditional use of chlorination. Photocatalysis combined with applied bias potential (photoelectrocatalysis) increases the efficiency of photocatalysis and decreases the charge recombination. This work examines the inactivation of fecal coliform bacteria present in real urban wastewater by photoelectrocatalysis using nanoparticulated films of TiO2 and TiO2/Ag (4%w/w) under UV light irradiation. The catalysts were prepared with different thicknesses by the sol-gel method and calcined at 400°C and 600°C. The urban wastewater samples were collected from the sedimentation tank effluent of the university sewage treatment facility. The rate of bacteria inactivation increases with increasing the applied potential and film thicknesses; also, the presence of silver on the catalyst surface annealed at 400°C shows better inactivation than that at 600°C. Finally, a structural cell damage of Escherichia coli (DH5α), inoculated in water, is observed during the photoelectrocatalytic process.

  4. Preparation and characterization of Ni-doped TiO2 materials for photocurrent and photocatalytic applications.

    PubMed

    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 TiO(2) (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 TiO(2) powders were evaluated by means of methylene blue (MB) degradation reaction under simulated solar light. Characterization results suggest that as a dopant, Ni stabilizes TiO(2) 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 TiO(2) have been enhanced by doping of Ni in TiO(2). The kinetic studies revealed that the MB degradation reaction follows the Langmuir-Hinshelwood first-order reaction relationship.

  5. 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

  6. Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

    NASA Astrophysics Data System (ADS)

    Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

    2016-10-01

    In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase JSC of the surface while slightly decreasing VOC compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

  7. Characterization of ALD Processed Gallium Doped TiO2 Hole Blocking Layer in an Inverted Organic Solar Cell

    NASA Astrophysics Data System (ADS)

    Lee, Eun Ju; Ryu, Sang Ouk

    2017-02-01

    To improve power conversion efficiency (PCE) of inverted structure organic solar cells a buffer layer, a hole blocking layer (HBL) was introduced between cathode and active photovoltaic layer. Gallium (Ga) doped TiO2 as a HBL was fabricated by means of atomic layer deposition. X-ray photoelectron spectroscopy showed the highest Ga-Ti complex binding characteristics was achieved at 5% doping concentration. Gallium doped TiO2 layer exhibited over 94% of optical transmittance at the process temperature of 200°C. The resulting PCE of inverted structure organic solar cell having 5% doping in the hole block layer was 2.7%. The PCE was improved 35% compared to the cell without gallium doping.

  8. Nitrogen doped TiO2 nanotube arrays with high photoelectrochemical activity for photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Yuan, Bao; Wang, Yan; Bian, Haidong; Shen, Tiankuo; Wu, Yucheng; Chen, Zhong

    2013-09-01

    Nitrogen doped TiO2 nanotube arrays (N-TNAs) were prepared by immersing TNAs in 1 M NH3·H2O solution and then annealing in different temperatures. The morphology, structure and composition of the N-TNAs were characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively. Effects of annealing temperatures on structure, photocatalytic properties, and the crystal structure transformation process of the N-TNAs were discussed. Photocatalytic properties of the N-TNAs were evaluated in term of the degradation of methyl orange (MO) under UV light and visible light, and the photocurrent of N-TNAs were tested by electrochemical workstation. The XPS results showed that the N-TNAs were achieved by interstitial doping and substitutional doping, and the FESEM results showed the morphology was not changed after doping process. Compared with the pure TNAs, the N-TNAs annealed at 500 ̊C for 2 h with a mixed phase of anatase and rutile exhibited higher photocatalytic degradation activity to MO. Furthermore, the photocatalytic mechanism of organic pollutants degradation (MO) was discussed based on our experiments.

  9. 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.

  10. 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.

  11. 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.

  12. In vitro antibacterial activity of porous TiO2-Ag composite layers against methicillin-resistant Staphylococcus aureus.

    PubMed

    Necula, Bogdan S; Fratila-Apachitei, Lidy E; Zaat, Sebastian A J; Apachitei, Iulian; Duszczyk, Jurek

    2009-11-01

    The aim of this study was the synthesis of a porous TiO(2)-Ag composite coating and assessment of its in vitro bactericidal activity against methicillin-resistant Staphylococcus aureus. The coating was produced by plasma electrolytic oxidation of Ti-6Al-7Nb medical alloy in a calcium acetate/calcium glycerophosphate electrolyte bearing Ag nanoparticles. Following oxidation, the surface of the titanium substrate was converted into the corresponding oxide (TiO(2)) bearing Ca and P species from the electrolyte. In addition, Ag was detected associated with particles present in the oxide layers. The coatings revealed a porous interconnected structure with pores up to 3 microm in size, a threefold increase in roughness and improved wettability relative to the non-oxidized specimens. The composite TiO(2)-Ag coating showed complete killing of methicillin-resistant S. aureus within 24h in all culture conditions, whereas a 1000-fold increase in bacterial numbers was recorded with the ground titanium specimens and the samples oxidized in the absence of Ag nanoparticles.

  13. 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...

  14. N-doped TiO2 Nanotubes as an Effective Additive to Improve the Catalytic Capability of Methanol Oxidation for Pt/Graphene Nanocomposites

    PubMed Central

    Wang, Xiaohua; Li, Yueming; Liu, Shimin; Zhang, Long

    2016-01-01

    N-doped TiO2 nanotubes have been prepared as additives to improve the catalytic capability of Pt/graphene composites in methanol oxidation reactions. Electrochemical experiments show that the catalytic performance of Pt/graphene composites has been greatly improved by the introduction of N-doped TiO2 nanotubes.

  15. Cu2O/Ag co-deposited TiO2 nanotube array film prepared by pulse-reversing voltage and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Ding, Qi; Chen, Suiyuan; Shang, Fanmin; Liang, Jing; Liu, Changsheng

    2016-12-01

    In this experiment, Cu2O/Ag co-deposition TiO2 nanotube array (Cu2O-Ag-TNT) film was prepared on pure Ti substrate with the method of combining anodic oxidation and electrodeposition by pulse-reversing voltage power supply in the electrolyte of NH4F, ethylene glycol, CuNO3 · 3H2O and AgNO3. The morphology, phase, chemical composition, photocatalytic property and mechanism of the nanotube array film were studied by means of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra, photoluminescence and photocatalytic degradation under visible light. The results showed that the depositional Cu2O and Ag existed in two forms, being the small-particle dispersion and large-particle sedimentary phase in the nanotube arrays: Cu2O-Ag-TNTs for different doping amounts of Ag could be prepared by adjusting the concentration of AgNO3 and the reverse voltages; with changing of the doping amount of Ag, the band gap and photo-generated electron-hole pair recombination rate also changed, and under the conditions of annealing and the optimized process parameter, the band gap of the nanotube arrays narrowed 0.49 eV and the rate of electron and pair recombination decreased noticeably; the nanotube array film for the concentration of 0.5 cm2 ml-1 degraded the methylene blue of 8 mg L-1, and the degradation rate reached above 98%. The co-deposition Cu2O-Ag-TNT film prepared by the one-step method performed well in the field of photocatalysis under visible light.

  16. Photocatalytic activity of tungsten-doped TiO2 with hydrothermal treatment under blue light irradiation.

    PubMed

    Putta, Thapanan; Lu, Ming-Chun; Anotai, Jin

    2011-09-01

    Tungsten doping and hydrothermal treatment were found to significantly improve the visible-light photoactivity of TiO(2) synthesized by the sol-gel method. It was observed that TiO(2) doped with a 0.5% W:Ti mole ratio and treated with 4 h of hydrothermal curing showed photoactivity under blue light irradiation equal to 74% of the commercial Degussa P-25 under UV irradiation, i.e., 0.01 mM 2-chlorophenol was completely removed in 120 and 90 min, respectively. Light absorptivity and photocatalytic activity under blue light irradiation were not dependent on the crystallite structure of the TiO(2). The oxidation kinetics under blue light irradiation can be effectively explained by the Langmuir-Hinshelwood model with an apparent reaction rate constant and a Langmuir constant of 3.60 × 10(-4) mM min(-1) and 206.53 mM(-1), respectively.

  17. 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.

  18. Effects of V heavy doping on the magnetic and optical properties in anatase TiO2

    NASA Astrophysics Data System (ADS)

    Hou, Qingyu; Zhao, Chunwang; Qu, Lingfeng

    2017-01-01

    A half-metal diluted magnetic semiconductor (DMS) can be formed in heavy V-doped TiO2. Contradictory experimental results in the literature have reported about the absorption spectra blueshift and redshift results in heavy V-doped TiO2. This study aims to reveal the mechanism of half-metal DMS in heavy V-doped TiO2 and solve the problem of absorption spectra blueshift and redshift in the doping system. In this study, models of the unit cells of pure anatase TiO2 and two V heavy-doped supercells of Ti0.96875V0.03125O2 and Ti0.9375V0.0625O2 were constructed based on density functional theory, which uses the first-principles plane-wave ultrasoft pseudopotential method. All models were obtained through geometry optimization. Local density approximation (LDA) + U was used to calculate the band structure, density of states (DOS), orbital charge and absorption spectrum of the doping system. The calculated results under the condition of electron spin showed that in the heavy doping concentration range, the volume of supercells increases, the total energy and formation energy decrease and the stability of the supercells increases as V doping concentration increases. Furthermore, the interaction of p-p states is weaker than that of p-d states, which results in the valence band maximum shifting toward the low-energy region, and also the optical bandgap becomes narrower as well as the redshift and intensity of the absorption spectrum become more notable. Noticeably, the hybrid coupling effect of Ti-3d and V-3d states becomes stronger, and the magnetic moment increases. The Fermi levels of spin-up band structure within the conduction band, which form the n-type degenerate semiconductors, and the Fermi levels of spin-down band structure within the bandgap indicate that the doping system has semiconductor features. Therefore, V-doped anatase TiO2 is an extremely promising DMS because of its high electron polarizability of nearly 100%. The calculation results are consistent with

  19. Cobalt-doped anatase TiO2: A room temperature dilute magnetic dielectric material

    NASA Astrophysics Data System (ADS)

    Griffin, K. A.; Pakhomov, A. B.; Wang, C. M.; Heald, S. M.; Krishnan, Kannan M.

    2005-05-01

    We experimentally investigate the room temperature ferromagnetism observed in insulating Co doped anatase TiO2 thin films grown by sputter deposition. The Co was uniformly incorporated in the lattice as Co(II) with no evidence of Co metal. A series of annealing treatments were carried out to optimize the ferromagnetic ordering and a saturation moment of 1.1μB/Co atom at 300 K was obtained with UHV annealing at 450 °C. Both as-deposited and annealed films were highly insulating at room temperature. Results show that the ferromagnetism is strongly dependent on the number and distribution of oxygen vacancies in the Co:TiO2 lattice.

  20. Niobium doped TiO2: Intrinsic transparent metallic anatase versus highly resistive rutile phase

    NASA Astrophysics Data System (ADS)

    Zhang, S. X.; Kundaliya, D. C.; Yu, W.; Dhar, S.; Young, S. Y.; Salamanca-Riba, L. G.; Ogale, S. B.; Vispute, R. D.; Venkatesan, T.

    2007-07-01

    We report on the structural, electrical, and optical properties of 5% niobium doped TiO2 thin films grown on various substrates by pulsed laser deposition. The epitaxial anatase Nb:TiO2 film on LaAlO3 is shown to be an intrinsic transparent metal and its metallic property arises from Nb substitution into Ti site as evidenced by the Rutherford backscattering channeling result. In contrast, the rutile Nb:TiO2 thin films show insulating behaviors with 2-3 orders higher room temperature electrical resistivity and ˜30 times lower mobility. A blueshift in the optical absorption edge is observed in both phases, though of differing magnitude.

  1. Electrical Properties and Defect Chemistry of In-Doped TiO2 in Terms of the Jonker Formalism.

    PubMed

    Nowotny, Janusz; Bak, Tadeusz; Ionescu, Mihail; Alim, Mohammad A

    2015-04-30

    The present work considers the semiconducting properties of In-doped TiO2 in terms of the Jonker formalism applied for both electrical conductivity and thermoelectric power data determined simultaneously in equilibrium with the gas phase of controlled oxygen activity. It is shown that the electrical properties of In-doped TiO2 annealed in oxidizing conditions [p(O2) > 10 Pa] can be described by the Jonker formalism very well. However, annealing of In-doped TiO2 in strongly reducing conditions [p(O2) < 10(-10) Pa], imposed by the gas phase involving hydrogen, results in a deviation of the experimental data from the Jonker's theoretical model derived for the Maxwell-Boltzmann statistics. This departure is considered in terms of the effect of hydrogen on the formation of structural domains, which are expected to be entirely different from those of oxidized TiO2 in terms of its electronic properties. It is argued that In-doped TiO2 annealed in the gas phase involving hydrogen exhibits a high concentration of donor-type ionic defects, which lead to the formation of high concentration of electrons. The related semiconducting properties are inconsistent with the model of classical semiconductor where the electrons are described by the Maxwell-Boltzmann statistics. It is concluded that strong interactions within the electron gas lead, in consequence, to the behavior resembling correlated transport of electrons. The obtained results suggest that indium incorporation into the rutile structure of TiO2 results in the formation of structural properties that exhibit extraordinary charge transport.

  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. 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.

  4. Fabrication and characterization of CdS doped TiO2 nanotube composite and its photocatalytic activity for the degradation of methyl orange.

    PubMed

    Chung, Jinwook; Kim, Seu-Run; Kim, Jong-Oh

    2015-01-01

    CdS doped TiO2 nanotube composite was fabricated by chemical bath deposition, and was characterized by the structural, spectral and photoelectrochemical properties. The results of the structural and spectral properties showed that CdS particles were successfully deposited onto the surface of TiO2 nanotube. It is demonstrated that CdS doped TiO2 nanotube composite improved the light harvesting ability. Power conversion efficiency of about 0.32% was observed. This value is about 2.9 times higher than that of pure TiO2 nanotube. The CdS doped TiO2 nanotube composite possesses relatively higher photocatalytic activity and photodegradation efficiency than that of pure TiO2 nanotube under UV light irradiation, and the degradation efficiency of methyl orange was about 42% at UV intensity of 32 W.

  5. A novel P/Ag/Ag2O/Ag3PO4/TiO2 composite film for water purification and antibacterial application under solar light irradiation.

    PubMed

    Zhu, Qi; Hu, Xiaohong; Stanislaus, Mishma S; Zhang, Nan; Xiao, Ruida; Liu, Na; Yang, Yingnan

    2017-01-15

    TiO2-based thin films have been intensively studied in recent years to develop efficient photocatalyst films to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, P/Ag/Ag2O/Ag3PO4/TiO2 composite films on the inner-surface of glass tube were successfully prepared via sol-gel approach. P/Ag/Ag2O/Ag3PO4/TiO2 composite films with 3 coating layers, synthesized at 400°C for 2h, showed the optimal photocatalytic performance for rhodamine B (Rh B) degradation. The results indicated that degradation ratio of Rh B by P/Ag/Ag2O/Ag3PO4/TiO2 composite film reached 99.9% after 60min under simulated solar light, while just 67.9% of Rh B was degraded by pure TiO2 film. Moreover, repeatability experiments indicated that even after five recycling runs, the photodegradation ratio of Rh B over composite film maintained at 99.9%, demonstrating its high stability. Photocatalytic inactivation of E. coli with initial concentration of 10(7)CFU/mL also showed around 100% of sterilization ratio under simulated solar light irradiation in 5min by the composite film. The radical trapping experiments implied that the major active species of P/Ag/Ag2O/Ag3PO4/TiO2 composite films were photo-generated holes and O2(-) radicals. The proposed photocatalytic mechanism shows that the transfer of photo-induced electrons and holes may reduce the recombination efficiency of electron-hole pairs and potential photodecomposition of composite film, resulting in enhanced photocatalytic ability of P/Ag/Ag2O/Ag3PO4/TiO2 composite films.

  6. Modulation of Crystal Surface and Lattice by Doping: Achieving Ultrafast Metal-Ion Insertion in Anatase TiO2.

    PubMed

    Wang, Hsin-Yi; Chen, Han-Yi; Hsu, Ying-Ya; Stimming, Ulrich; Chen, Hao Ming; Liu, Bin

    2016-10-11

    We report that an ultrafast kinetics of reversible metal-ion insertion can be realized in anatase titanium dioxide (TiO2). Niobium ions (Nb5+) were carefully chosen to dope and drive anatase TiO2 into very thin nanosheets standing perpendicularly onto transparent conductive electrode (TCE) and simultaneously construct TiO2 with an ion-conducting surface together with expanded ion diffusion channels, which enabled ultrafast metal ions diffusion across the electrolyte/solid interface and into the bulk of TiO2. To demonstrate the superior metal-ion insertion rate, the electrochromic features induced by ion intercalation were examined, which exhibited the best color switching speed of 4.82 s for coloration and 0.91 s for bleaching among all reported nano-sized TiO2 devices. When performed as the anode for the secondary battery, the modified TiO2 was capable to deliver a highly reversible capacity of 61.2 mAh g-1 at an ultrahigh specific current rate of 60 C (10.2 A g-1). This fast metal-ion insertion behavior was systematically investigated by the well-controlled electrochemical approaches, which quantitatively revealed both the enhanced surface kinetics and bulk ion diffusion rate. Our study could provide a facile methodology to modulate the ion diffusion kinetics for metal oxides.

  7. Nitrogen-doped carbon-embedded TiO2 nanofibers as promising oxygen reduction reaction electrocatalysts

    NASA Astrophysics Data System (ADS)

    Hassen, D.; Shenashen, M. A.; El-Safty, S. A.; Selim, M. M.; Isago, H.; Elmarakbi, A.; El-Safty, A.; Yamaguchi, H.

    2016-10-01

    The development of inexpensive and effective electrocatalysts for oxygen reduction reaction (ORR) as a substitute for commercial Pt/C catalyst is an important issue in fuel cells. In this paper, we report on novel fabrication of self-supported nitrogen-doped carbon-supported titanium nanofibers (Nsbnd TiO2@C) and carbon-supported titanium (TiO2@C) electrocatalysts via a facile electrospinning route. The nitrogen atom integrates physically and homogenously into the entire carbon-titanium structure. We demonstrate the catalytic performance of Nsbnd TiO2@C and TiO2@C for ORR under alkaline conditions in comparison with Pt/C catalyst. The Nsbnd TiO2@C catalyst shows excellent ORR reactivity and durability. Interestingly, among all the catalysts used in this ORR, Nsbnd TiO2@C-0.75 exhibits remarkable competitive oxygen reduction activity in terms of current density and onset potential, as well as superior methanol tolerance. Such tolerance attributes to maximizing the diffusion of trigger pulse electrons during catalytic reactions because of enhanced electronic features. Results indicate that our fabrication strategy can provide an opportunity to produce a simple, efficient, cost-effective, and promising ORR electrocatalyst for practical applications in energy conversion and storage technologies.

  8. Preparation of Fe-doped TiO2 nanotube arrays and their room-temperature ferromagnetic properties.

    PubMed

    Wang, Jianli; Liu, Chao; Shen, Weidong; Cao, Chunlan; Song, Sihong

    2014-08-01

    Fe-doped titania nanotube arrays (NTs) were fabricated by electrochemical anodization on a Ti foil using Fe(NO3)3 · 2H2O as iron source. Their morphology, structure and optical properties were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-visible absorption spectroscopy and photoluminescence spectroscopy. The UV-visible reflection spectrum of the Fe-doped TiO2 NTs showed a red shift in wavelength of absorption and greater reflectivity compared with the undoped sample due to the Fe ion incorportion in TiO2 lattices. The photoluminescence spectrum of the Fe-doped TiO2 NTs shows two strong new peaks centered at 388 nm and 694 nm, besides the UV emission peak owing to the electronic transition mediated by the defect levels such as oxygen vacancies in the band gap. The magnetic property of the Fe-doped TiO2 NTs exhibits a room temperature ferromagnetic characteristic with a saturation magnetization (Ms) of 0.146 x 10(-2) emu/cm3 and a coercive field of 60 Oe. And the cause of the magnetic properties has been discussed in detail.

  9. Photoelectrocatalytic properties of nitrogen doped TiO2/Ti photoelectrode prepared by plasma based ion implantation under visible light.

    PubMed

    Han, Lei; Xin, Yanjun; Liu, Huiling; Ma, Xinxin; Tang, Guangze

    2010-03-15

    Nitrogen doped TiO(2)/Ti photoelectrodes were prepared by a sequence of anodization and plasma based ion implantation (PBII). The properties of this photoelectrode were characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), Ultra violet/visible light diffuse reflectance spectra (UV/vis/DRS), surface photovoltage (SPV), etc. Photoelectrocatalytic (PEC) performance of N-doped TiO(2)/Ti photoelectrode was tested under visible light irradiation. Their photocatalytic activity was evaluated by degradation of Rhodamine B (Rh.B). The results of XPS showed that nitrogen element was in form of three species, i.e. beta-N, molecular gamma-N and O-Ti-N, which existed in the lattices of TiO(2) and gaps between molecules. The results of UV/vis/DRS spectra and SPV revealed that proper doping of nitrogen could expand the response of photoelectrodes towards visible light and diminish the recombination of photo-generated holes and electrons, respectively. The photoelectrocatalytic activity of N-doped TiO(2)/Ti photoelectrodes was superior to those of undoped one under visible light region irradiation.

  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

    2016-06-05

    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.

  11. Important role of surface fluoride in nitrogen-doped TiO2 nanoparticles with visible light photocatalytic activity.

    PubMed

    Brauer, Jonathan I; Szulczewski, Greg

    2014-12-11

    Nitrogen-doped TiO2 nanoparticles have been synthesized using sol-gel methods and subsequently fluorinated at room temperature by aging in acidic solutions of NaF. The nanoparticles were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, UV-vis, and IR diffuse reflectance spectroscopy. After aging at room temperature in NaF solutions, the Ti-OH groups on the surface of the TiO2 nanoparticles were replaced by Ti-F bonds, which resulted in a decrease of the point of zero charge from pH 5.4 to 2.8. Most importantly, the nitrogen dopants were retained after the fluorination process, and the amorphous nanoparticles were partially converted into the anatase phase. Annealing the photocatalysts resulted in a decrease of both the nitrogen and fluoride atomic concentration. Diffuse reflectance spectra show an increase in absorbance above 400 nm after annealing the F,N-doped TiO2, which suggests the formation of color centers. The photoactivity of the F,N-doped and N-doped TiO2 catalysts were evaluated by monitoring by the decolorization of methylene blue with visible light. Mass spectrometric analysis revealed that methylene blue undergoes successive demethylation, and more importantly, the rate of decolorization depends on the fluoride concentration. These results show the importance of a two-step synthesis method to independently control the nitrogen and fluoride concentration.

  12. Highly Active TiO2-Based Visible-Light Photocatalyst with Nonmetal Doping and Plasmonic Metal Decoration

    SciTech Connect

    Zhang, Qiao; Lima, Diana Q.; Chi, Miaofang; Yin, Yadong

    2011-01-01

    A sandwich-structured photocatalyst shows an excellent performance in degradation reactions of a number of organic compounds under UV, visible light, and direct sunlight (see picture). The catalyst was synthesized by a combination of nonmetal doping and plasmonic metal decoration of TiO2 nanocrystals, which improves visible-light activity and enhances light harvesting and charge separation, respectively.

  13. 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...

  14. Yttrium doped TiO2 porous film photoanode for dye-sensitized solar cells with enhanced photovoltaic performance

    NASA Astrophysics Data System (ADS)

    Qu, Xiaofei; Hou, Yuchen; Liu, Meihua; Shi, Liang; Zhang, Mingqian; Song, Hongbing; Du, Fanglin

    In this paper, TiO2 photoanodes were doped with yttrium under different doping concentrations via hydrothermal method and further employed to assemble dye-sensitized solar cells (DSSCs). XRD, XPS, SEM, TEM, UV-Vis DRS and PL measurements were carried out to investigate the yttrium doping effects on crystal structure, chemical status, optical properties and dye loading capacity of the photoanodes. The photovoltaic performance of the photoanodes with various yttrium doping concentration was measured by recording the photocurrent-photovoltaic curves, and the result indicated that TiO2:0.006 Y exhibited the best power conversion efficiency with high short circuit current density (Jsc) and open circuit voltage (Voc). This improvement may be due to the enhanced visible light harvesting, increased dye loading capacity and reduced photoelectron recombination.

  15. 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.

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

    PubMed

    Hu, Hongwei; Ding, Jianning; Zhang, Shuai; Li, Yan; Bai, Li; Yuan, Ningyi

    2013-01-03

    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.

  17. 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

  18. 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.

  19. Au or Ag nanoparticle-decorated 3D urchin-like TiO2 nanostructures: synthesis, characterization, and enhanced photocatalytic activity.

    PubMed

    Xiang, Liqin; Zhao, Xiaopeng; Shang, Chaohong; Yin, Jianbo

    2013-08-01

    The semiconductors decorated with noble metals have attracted increasing attention due to their interesting physical and chemical properties. Here, 3D urchin-like hierarchical TiO2 nanostructures decorated with Au or Ag nanoparticles were prepared by wet-chemical process. The morphology and structure were characterized by different techniques. It shows that Au or Ag nanoparticles with narrow distribution are uniformly loaded on urchin-like TiO2 nanostructures, and the resulted composite nanostructures show distinct surface plasmon absorption band and quenched photoluminence compared to pure TiO2 nanostructures. Photocatalytic tests show both Au-decorated TiO2 and Ag-decorated TiO2 exhibit enhanced photocatalytic activity for photodegradation of methyl blue in water.

  20. 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.

  1. The investigation of photo-induced chemiluminescence on Co2+-doped TiO2 nanoparticles and its analytical application.

    PubMed

    Li, Guixin; Nan, Hongyan; Zheng, Xingwang

    2009-07-01

    A novel space- and time-resolved photo-induced chemiluminescence (PICL) analytical method was developed based on the photocatalysis of the Co2+-doped TiO2 nanoparticles. The PICL reaction procedure under the photocatalysis of Co2+-doped TiO2 nanoparticles was investigated using cyclic voltammetry and potentiometry. Meanwhile, the effect of the electrical double layer outside the Co2+-doped TiO2 nanoparticles on the PICL was investigated by contrasting with the Co2+-doped TiO2-SiO2 core-shell nanoparticles. Significantly, the CL intensity increased apparently and the time of the CL was prolonged in the presence of procaterol hydrochloride because the mechanism of the enhanced PICL reaction may be modified. The route of the PICL was changed due to the participation of the procaterol hydrochloride enriched at the surface of the Co2+-doped TiO2-SiO2 in the PICL reaction, which prolonged the time of the CL reaction and resulted in the long-term PICL. The analytical characteristics of the proposed in-situ PICL method were investigated using the procaterol hydrochloride as the model analyte. The investigation results showed that this new PICL analytical method offered higher sensitivity to the analysis of the procaterol hydrochloride and the PICL intensity was linear with the concentration of the procaterol hydrochloride in the range from ca. 2.0 x 10(-10) to 1.0 x 10(-8) g mL(-1).

  2. Synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles and nanowires

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh

    2010-01-01

    We present the synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles (NPs) and TiO2 nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag2S NPs and TiO2 NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag2S NPs on TiO2 NWs was created. Due to the coupling with such a low bandgap material as Ag2S, the TiO2 nanocomposites could have a visible-light absorption capability much higher than that of pure TiO2. As a result, the synthesized Ag2S/TiO2 nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO2 (Degussa P25, Germany) under visible light.

  3. Preparation and characterization of visible-light-driven TiO2 photocatalyst Co-doped with nitrogen and erbium.

    PubMed

    Chen, Guihua; Wang, Yong; Zhang, Juihui; Wu, Chenglin; Liang, Huading; Yang, Hui

    2012-05-01

    A series of nitrogen and erbium co-doped TiO2 photocatalyst was prepared by sol-hydrothermal method. The structure and properties of the photocatalyst were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra (DRS). The XRD and BET results showed that co-doping inhibited the increase of crystallite size and enlarged specific surface areas. XPS spectroscopy indicated nitrogen atoms were incorporated into TiO2 lattice, and erbium atoms mostly existed in the forms of Er2O3. A shift of the absorption edge to the lower energy and four absorption bands located at 654, 544, 524 and 489 nm attributed to the 4f transitions of 4I15/2 --> 4F2/9, 4I15/2 --> 4S3/2, 4I15/2 --> 2H11/2, 4I15/2 --> 4F7/2 of Er3+ were observed using DRS spectroscopy. The catalytic efficency was evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. The results showed that the photocatalytic performance of the co-doped TiO2 was related with the hydrothermal temperature and the molar ratio of N/Ti, and they showed higher acitivites than pure TiO2. Results determined by fluorescence technique revealed that irradiation (lambda > 400 nm) of TiO2 photocatalyst dispersed in MO solution induces the generation of the highly active hydroxyl radicals (OH). It indicated the photocatalytic activities of TiO2 photocatalyst were correlation with the formation rate of hydroxyl radicals (OH) and other active oxygen species.

  4. Experimental and theoretical study of the electronic properties of Cu-doped anatase TiO2.

    PubMed

    Navas, Javier; Sánchez-Coronilla, Antonio; Aguilar, Teresa; Hernández, Norge C; de los Santos, Desireé M; Sánchez-Márquez, Jesús; Zorrilla, David; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Martín-Calleja, Joaquín

    2014-02-28

    A good correlation was obtained between the electronic properties of Cu-doped anatase TiO2 by virtue of both physical chemistry characterization and theoretical calculations. Pure and Cu-doped TiO2 were synthesized. The composition, structural and electronic properties, and the band gap energy were obtained using several techniques. The method of synthesis used produces Cu-doped anatase TiO2, and XRD, XPS and Raman spectroscopy indicate that Cu atoms are incorporated in the structure by substitution of Ti atoms, generating a distortion of the structure and oxygen vacancies. In turn, the band gap energy of the synthesized samples decrease drastically with the Cu doping. Moreover, periodic density functional theory (DFT-periodic) calculations were carried out both to model the experimentally observed doped structures and to understand theoretically the experimental structures obtained, the formation of oxygen vacancies and the values of the band gap energy. From the analysis of density of states (DOS), projected density of states (PDOS) and the electron localization function (ELF) a decrease in the band gap is predicted upon increasing the Cu doping. Thus, the inclusion of Cu in the anatase structure implies a covalent character in the Cu-O interaction, which involves the appearance of new states in the valence band maximum with a narrowing in the band gap.

  5. Application of nitrogen-doped TiO2 nano-tubes in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Tran, Vy Anh; Truong, Trieu Thinh; Phan, Thu Anh Pham; Nguyen, Trang Ngoc; Huynh, Tuan Van; Agresti, Antonio; Pescetelli, Sara; Le, Tien Khoa; Di Carlo, Aldo; Lund, Torben; Le, So-Nhu; Nguyen, Phuong Tuyet

    2017-03-01

    Our research aimed to improve the overall energy conversion efficiency of DSCs by applying nitrogen-doped TiO2 nano-tubes (N-TNT) for the preparation of DSCs photo-anodes. The none-doped TiO2 nano-tubes (TNTs) were synthesized by alkaline hydrothermal treatment of Degussa P25 TiO2 particles in 10 M NaOH. The nano-tubes were N-doped by reflux in various concentrations of NH4NO3. The effects of nitrogen doping on the structure, morphology, and crystallography of N-TNT were analyzed by transmission electron microscopy (TEM), infrared spectroscopy (IR), Raman spectroscopy, and X-ray photoelectron spectra (XPS). DSCs fabricated with doped N-TNT and TNT was characterized by J-V measurements. Results showed that nitrogen doping significantly enhanced the efficiency of N-TNT cells, reaching the optimum value (η = 7.36%) with 2 M nitrogen dopant, compared to η = 4.75% of TNT cells. The high efficiency of the N-TNT cells was attributed to increased current density due to the reduction of dark current in the DSCs.

  6. 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%).

  7. Shape transformation and relaxation dynamics of photoexcited TiO2/Ag nanocomposites.

    PubMed

    Kim, Mee Rahn; Ah, Chil Seong; Shin, Dongha; Lee, Sang Kyung; Lee, Wan In; Jang, Du-Jeon

    2008-06-01

    The laser-induced sintering of TiO2 nanoparticles into larger nanospheres is accelerated by adsorbed silver particles. For the same weight fraction of silver, silver nanoparticles of 5 nm in diameter modify TiO2 nanoparticles more effectively than those of 1.5 nm do, suggesting that the photocatalysis of TiO2 nanoparticles as well as their stability is highly dependent on the sizes, the shapes, and the distribution of adsorbed metal nanoparticles. The photoexcited electrons of TiO2 nanoparticles are quenched at trap sites and surface states by transfer to the conduction band of silver, implying that the presence of adsorbed silver nanoparticles enhances the photocatalytic effect of TiO2.

  8. N-doped TiO2 based visible light activated label-free photoelectrochemical biosensor for detection of Hg(2+) through quenching of photogenerated electrons.

    PubMed

    Han, Qianqian; Wang, Kewei; Xu, Lijun; Yan, Xiang; Zhang, Kunchi; Chen, Xing; Wang, Qinglin; Zhang, Lan; Pei, Renjun

    2015-06-21

    A novel photoelectrochemical (PEC) biosensor was fabricated based on N-doped TiO2 for the detection of Hg(2+) through the quenching of photogenerated electrons. The N-doped TiO2 was synthesized by a sol-gel method with urea and tetrabutyl titanate as the N and Ti sources. Compared with the undoped TiO2, the N-doped TiO2 showed an enhanced photocurrent response under visible light (λ > 420 nm). The sensing surface was functionalized with 5'-amino-modified T-rich oligonucleotides. The photoelectrochemical biosensor bound Hg(2+) on the surface by a highly specific T-Hg(2+)-T recognition. Hg(2+) on the surface of the N-doped TiO2 film withdrew the photogenerated electrons and decreased the recorded current signal. The dynamic linear range for Hg(2+) has been determined to be as low as 2-6 μM.

  9. Ultraviolet-visible absorption spectra of N-doped TiO2 film deposited on sapphire

    NASA Astrophysics Data System (ADS)

    Park, Jaewon; Lee, Jung-Yup; Cho, Jun-Hyung

    2006-12-01

    The optical-response properties of nitrogen(N)-doped titanium dioxide (TiO2) films are investigated by means of a combination of ultraviolet-visible absorption spectroscopy and first-principles density-functional calculations. The TiO2 films were epitaxially grown on the sapphire substrate by the pulsed laser deposition method. The doping of N atoms was achieved by 70keV of N+ ion implantation, followed by postirradiation heat treatment at 550°C for 2h in air. We find that when 5×1016 (1×1017)Nions/cm2 were implanted into the epitaxially grown TiO2 film, the absorption edge is reproducibly shifted to lower energy by about 0.06 (0.12)eV together with a significant optical absorption extending into the visible-light region. These experimental data can be explained by our calculated band structure of N-doped TiO2, where the bands originating from N 2p states locate above the valence band edge, while the band gap narrowing due to the mixing of N with O 2p states is 0.04eV.

  10. Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Ren, Fu-jian; Yu, Xiao-bai; Ling, Yun-han; Feng, Jia-you

    2012-05-01

    In-situ pure TiO2 and Fe-doped TiO2 thin films were synthesized on Ti plates via the micro-arc oxidation (MAO) technique. The as-fabricated anatase TiO2 thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO2 thin films by adding precursor K4(FeCN)6·3H2O into the Na3PO4 electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of K4(FeCN)6·3H2O increasing, eventually affecting the ethanol sensing performances of TiO2 thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant (1.28at%), by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275°C. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe3+ substituting for Ti4+.

  11. 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.

  12. A study on the band gap and the doping level of V-doped TiO2 with respect to the visible-light photocatalytic activity.

    PubMed

    Choi, Ah Young; Han, Chul-Hee

    2014-10-01

    The visible-light response is a necessary but not a sufficient condition for semiconductor photocatalyst to function as a visible-light active photocatalyst. To shed more light on the issue of visible-light response of semiconductor photocatalysts, the band-gaps and the doping levels of multivalency vanadium-doped TiO2 were investigated from sonochemically prepared samples. Sonochemical doping, which relies on acoustic cavitation phenomena, is a one step process excluding chemical synthesis, and three types of vanadium doped TiO2 nanopowder were prepared using such vanadium oxides as V2O3, V2O4, and V2O5. The band-gaps of as-prepared samples were obtained from the diffuse reflectance measurement, and the doping levels of vanadium in these samples were measured using electron probe micro analyzer. In addition, X-ray photoelectron spectrometer was introduced to complement electron probe micro analyzer. Furthermore, quantum-chemical calculations on simple cluster models for TiO2 and V-doped TiO2 were performed, and the resulting computational results in conjunction with experimental findings provided valuable information on oxygen vacancy and doping mechanism.

  13. 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

  14. Optical and dielectric properties of TiO2 doped PVA-CN/LiClO4 composite electrolyte

    NASA Astrophysics Data System (ADS)

    Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.

    2013-02-01

    Solid polymer electrolyte (SPE) composite films of PVA-CN-HOBt-LiClO4 doped with TiO2 were prepared by solution casting method. The films were characterized using FT-IR, UV-Vis, DSC and Dielectric studies at room temperature. The FTIR results show the interaction of TiO2 nanoparticles with PVA-CN-HOBt-LiClO4 composite. The optical absorbance of the composite films increases from 250nm to 400nm with increase in doping and optical band gap (Eg) decreases from 3.2eV to 3.1eV. The glass transition temperature increases with increase in doping level. The dielectric properties of the composites show that these composite films can be used for SPE nanocomposites.

  15. Nitrogen and vanadium Co-doped TiO2 mesosponge layers for enhancement in visible photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Zhong, Jiasong; Xu, Jinrong; Wang, Qingyao

    2014-10-01

    Novel N and V co-doped TiO2 mesosponge (N-V-TMSW) layers were successfully prepared by one-step hydrothermal treatment of TiO2 nanotube arrays, and the phase composition, morphology and optical property were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffusion reflectance spectroscopy (DRS). The crystal structure and density of states were studied by means of the first-principle pseudo-potential plane wave. The results indicated that titanium ions and oxygen atoms in TiO2 were successfully substituted by vanadium ions and nitrogen atoms, respectively. The sample N-V0.1-TMSW showed a remarkable absorption in the visible light range of 400-600 nm and high visible photocatalytic activity

  16. Grain size dependence of electrical and optical properties in Nb-doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Yang, J. Y.; Li, W. S.; Li, H.; Sun, Y.; Dou, R. F.; Xiong, C. M.; He, L.; Nie, J. C.

    2009-11-01

    Anatase thin films of pure TiO2 and 6% niobium doped TiO2 (Nb:TiO2) were fabricated on LaAlO3(100) by pulsed laser deposition. The electrical properties of Nb:TiO2 films are grain-size dependent, i.e., the larger grain size, the higher conductivity, and mobility. For all TiO2 and for Nb:TiO2 with small mean grain size (d <15 nm), the band gap energy is found to increase systematically with the decrease in d, which is consistent with the quantum confinement model. For the films with large mean grain size (d >15 nm), particularly, a blueshift in Nb:TiO2 is governed by the Burstein-Moss effect.

  17. Phosphate modified N/Si co-doped rutile TiO2 nanorods for photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofan; Zhang, Bingyan; Luo, Yanping; Lv, Xiaowei; Shen, Yan

    2017-01-01

    Surface modification of TiO2 film provides possibilities to improve photoelectrochemical (PEC) activity. In this study, we report on phosphate modified N/Si co-doped TiO2 nanorods films (Pi-N/Si-TiO2 NRs) for PEC water oxidation. Compared to the pristine TiO2 NRs, the Pi-N/Si-TiO2 NRs photoanode shows a 4.65-fold enhanced photocurrent density (1.44 mA cm-2) under light illumination. This significant improvement can be attributed to the synergistic effect of phosphate modification and the N and Si co-dopants. In addition to the improvement of ultraviolet and visible light response by N and Si co-dopants, phosphate modification is mainly responsible for charge transfer at the interface of the photoanode/electrolyte.

  18. Synthesis, characterization and photocatalytic applications of Zn-doped TiO2 nanoparticles by sol-gel method

    NASA Astrophysics Data System (ADS)

    Aware, Dinkar V.; Jadhav, Shridhar S.

    2016-10-01

    Mesoporous, nanocrystalline, Zinc-doped TiO2 nanoparticles were synthesized by surfactant-assisted sol-gel method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-VIS spectrometer techniques were used to characterize the synthesized products. XRD results confirm the formation of the anatase phase for the TiO2 nanoparticles, with crystallite sizes in the range of 12.6-18.1 nm. The small crystallite size and doping with Zinc ion inhibit phase transformation and promote the growth of the TiO2 anatase phase. The SEM and TEM micrographs revealed the spherical-like morphology with average diameter of about 12-18 nm which is in agreement with XRD results. The optical study shows that doping ions lead to an increase in the absorption edge wavelength and a decrease in the band gap energy of titania. Photocatalytic activity of the synthesized nanomaterials was successfully tested for photodegradation of methyl red as model pollutant under UV light. The photocatalytic activity results confirm that the doped nanoparticles show higher activity than undoped titania. The small grain size, high crystallinity, high specific surface area and decrease in the band gap energy of doped titania may be responsible for the high photocatalytic activity.

  19. TiO2 nanopowder co-doped with iodine and boron to enhance visible-light photocatalytic activity.

    PubMed

    Ding, Jianqiang; Yuan, Yali; Xu, Jinsheng; Deng, Jian; Guo, Jianbo

    2009-10-01

    An iodine and boron co-doped TiO2 photocatalyst was prepared by the hydrolyzation-precipitation method. X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the crystalline structure, light absorbing ability, and the chemical state of iodine and boron in the photocatalysts. The results of photocatalytic degradation of methyl orange demonstrated that the I-B-TiO2 catalyst prepared at 400 degrees C for 3 h exhibited the highest photocatalytic activity with a methyl orange degradation ratio of 61% under visible-light (lambda > or = 420 nm) irradiation for 120 min. The characterization results revealed that I-B-TiO2 is in conformity with the anatase TiO2 and that the doping of iodine and boron ions could efficiently inhibit the grain growth. Doped iodine was present in the multivalent forms of 17+, I- and I5+. Doped boron was present as B3+ in an as-prepared sample, forming a possible chemical environment such as B-O-Ti. Overall, the doping of I and B enhanced the ability of TiO2 to absorb visible-light, and it was observed that the photocatalytic activity of I-B-TiO2 was enhanced by the synergistic effect of I and B.

  20. FABRICATION AND PHOTOCATALYTIC PROPERTIES OF TiO2 NANOFILMS CO-DOPED WITH Fe3+ AND Bi3+ IONS

    NASA Astrophysics Data System (ADS)

    Gao, Qiongzhi; Liu, Xin; Liu, Wei; Liu, Fang; Fang, Yueping; Zhang, Shiying; Zhou, Wuyi

    2016-12-01

    In this work, the titanium dioxide (TiO2) nanofilms co-doped with Fe3+ and Bi3+ ions were successfully fabricated by the sol-gel method with dip-coating process. Methylene blue was used as the target degradation chemical to study the photocatalytic properties affected by different doping contents of Fe3+ and Bi3+ ions. The samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and infrared (IR) spectroscopy. The results indicated that both pure TiO2 nanofilms and single-doped samples possessed the photocatalytic activity in degradation of methylene blue. However, when the nanofilms co-doped with Fe3+ and Bi3+ ions were fabricated at the molar ratio of 3:1 (Fe3+:Bi3+), they exhibited the best photocatalytic activity after the heat treatment at 500∘C for 2h. The wettability property test indicated that the TiO2 nanofilms co-doped with Fe3+ and Bi3+ ions in the molar ratio 3:1 owned an excellent hydrophilic property.

  1. Removal of phenanthrene in aqueous solution containing photon competitors by TiO2-C-Ag film supported on fiberglass.

    PubMed

    González-Ramírez, Denisse Fabiola; Ávila-Pérez, Pedro; Torres-Bustillos, Luis G; Aguilar-López, Ricardo; Montes-Horcasitas, María C; Esparza-García, Fernando J; Rodríguez-Vázquez, Refugio

    2017-04-10

    Surface interactions with pollutants and photons are key factors that affect the applications of TiO2 in environmental remediation. In this study, the solubilizing agents dimethylsulfoxide and polyoxyethylene sorbitan monooleate, which act as photon competitors, had no effect on the photocatalytic activity of TiO2-C-Ag film in phenanthrene (PHE) removal. Fiberglass with TiO2-C-Ag coating removed 91.1 ± 5.2 and 99.7 ± 0.4% of PHE in treatments using UVA (365-465 nm) and UVC (254 nm) irradiation, respectively. The use of fiberglass as a support increased the superficial area, thus allowing PHE sorption. C and Ag, which are electrically active impurities in TiO2, enhanced its photocatalytic activity and thus the attraction of the pollutant to its surface. The use of high-frequency UV light (UVC) decreased the amount of carbon species deposited on the TiO2CAg film surface. X-ray photoelectron spectroscopy of the TiO2-C-Ag film revealed extensive oxidation of the carbon deposited on the film under UVC light and loss of electrons from Ag clusters by conversion of Ag(0) to Ag(3+).

  2. 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

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

    PubMed

    Xing, Mingyang; Li, Xiao; Zhang, Jinlong

    2014-06-30

    TiO2/graphene (TiO2-x/GR) composites, which are Ti(3+) 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 Ti(3+) self-doping on TiO2 nanorods and boron doping on graphene.

  4. 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

  5. Correction: 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

    2015-12-28

    Correction for 'Enhancing carrier generation in TiO2 by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interference' by Giuseppe Cacciato et al., Nanoscale, 2015, 7, 13468-13476.

  6. Density functional theory studies on the structural and physical properties of Cu-doped anatase TiO2(101) surface

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Yin, Jiu-Ren; Tang, Xian-Qiong; Zhang, Ping; Ding, Yan-Huai

    2017-01-01

    Structure and physical properties of anatase TiO2 (101) surface doped with copper have been studied by using density functional theory. Results show that Cu@Ti and Cu@O systems behave as p and n type semiconductors, respectively. Anatase TiO2 (101) surface exhibits a blue shift in optical absorption spectra compared with pure TiO2 bulk materials. Enhanced photocatalytic activity at wavelength around 400 nm could be contributed by the change in electronic structure.

  7. Self-doped Ti(3+)-TiO2 as a photocatalyst for the reduction of CO2 into a hydrocarbon fuel under visible light irradiation.

    PubMed

    Sasan, Koroush; Zuo, Fan; Wang, Yuan; Feng, Pingyun

    2015-08-28

    Self-doped TiO2 shows visible light photocatalytic activity, while commercial TiO2 (P25) is only UV responsive. The incorporation of Ti(3+) into TiO2 structures narrows the band gap (2.90 eV), leading to significantly increased photocatalytic activity for the reduction of CO2 into a renewable hydrocarbon fuel (CH4) in the presence of water vapour under visible light irradiation.

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

    PubMed

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

    2016-08-05

    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.

  9. 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.

  10. Niobium-Doped (001)-Dominated Anatase TiO2 Nanosheets as Photoelectrode for Efficient Dye-Sensitized Solar Cells.

    PubMed

    Jiang, Lei; Sun, Lei; Yang, Dong; Zhang, Jian; Li, Ya-Juan; Zou, Kun; Deng, Wei-Qiao

    2017-03-22

    TiO2 nanocrystals with different reactive facets have attracted extensive interest since they were first synthesized. The anatase TiO2 nanocrystals with (001) or (100) dominate facets were considered to be excellent electrode materials to enhance the cell performance of dye-sensitized solar cells. However, which reactive facet presents the best surface for benefiting photovoltaic effect is still unknown. We report a systematic study of various anatase TiO2 surfaces interacting with N719 dye by means of density functional theory calculations in combination with microscopic techniques. The (001) surface interacting with N719 would have the lowest work function, leading to the best photovoltaic performances. To further increase the efficiency, Nb dopant was incorporated into the anatase TiO2 nanocrystals. Based on the theoretical prediction, we proposed and demonstrated novel Nb-doped (001)-dominated anatase TiO2 nanosheets as photoelectrode in a dye-sensitized solar cell to further enhance the open-circuit voltage. And a power conversion efficiency of 10% was achieved, which was 22% higher than that of the undoped device (P25 as an electrode).

  11. Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe3O4-TiO2

    NASA Astrophysics Data System (ADS)

    Jia, Xiaohua; Dai, Rongrong; Lian, Dandan; Han, Song; Wu, Xiangyang; Song, Haojie

    2017-01-01

    Fe3O4-TiO2 heterostructures were synthesized through co-precipitation method based on TiO2 nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO2 nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe3O4 nanoparticles were adhere to TiO2 nanobelts which have one-dimensional structure with 100-200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe3O4-TiO2 nanocomposites studies confirm that Ag is in Ag0 state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV-vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO2 due to the higher degree of recombination reactions after combined with Fe3O4 nanoparticles. After coated the composite of 15% Fe3O4-TiO2 with Ag, the new nanocomposite of Ag@Fe3O4-TiO2 can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of Ag nanoparticle decorated Fe3O4-TiO2 nanocomposites with surface heterostructures are discussed.

  12. 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.

  13. 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

    2016-03-17

    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.

  14. 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

  15. 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.

  16. UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

    PubMed

    Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

    2014-10-01

    Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

  17. [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.

  18. 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.

  19. Carbon wrapped and doped TiO2 mesoporous nanostructure with efficient visible-light photocatalysis for NO removal

    NASA Astrophysics Data System (ADS)

    He, Di; Li, Yongli; Wang, inshu; Wu, Junshu; Yang, Yilong; An, Qier

    2017-01-01

    Carbon wrapped and doped mesoporous anatase TiO2 nanocrystals were prepared by a hydrothermal approach in acetic acid aqueous containing chitosan. A designed post-thermal treatment was employed to enhance the incorporation between carbon and TiO2. After hydrothermal process, mesoporous anatase TiO2 formed with wrapped by a few layers of carbon shell. Here chitosan was used as not only the template for the formation of mesopores, but also the carbon source toward the carbon layers coating. Furthermore, chitosan provided doping element into TiO2 lattice and induced to form Tisbnd C bond which caused Ti(III) with oxygen vacancies. The Ti(III)-oxygen vacancy are partly responsible for visible-light response and high photocatalytic activity, which can accelerate electron transfer thus inhibit photogenerated charge recombination. The photocatalytic activity was evaluated using photo-oxidation of gaseous NO under visible light irradiation as the probe reaction. In the optimum result, 71% of NO with starting concentration at ppb level was photo-degraded. Our results also showed that the photogenerated electrons played a key role in photodegradation of NO, as a result, the environmental humidity level had a negligible effect on the photocatalysis.

  20. 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.

  1. 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.

  2. Effects of Fe Doping on the Structural, Optical, and Magnetic Properties of TiO2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Thu, Dang Xuan; Trung, Vu Quoc; Nghia, Nguyen Manh; Khang, Nguyen Cao; Lam, Tran Dai

    2016-11-01

    Fe-doped TiO2 nanoparticles have been prepared by the hydrolysis method. The effects of Fe doping on the structural, optical, and magnetic properties of the Ti1- x Fe x O2 ( x = 0.00, 0.03, 0.06, 0.10, 0.13) materials were thoroughly investigated by a combination of various methods, including transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, x-ray diffraction (XRD) analysis, ultraviolet-visible (UV-Vis) reflectance spectroscopy, Raman spectroscopy, and vibrating-sample magnetometry. Analysis of the TEM and XRD measurements showed that the resulting powders had nanoscale particle size. The Fe-doped samples were found to be paramagnetic at room temperature (by magnetization measurements), with Fe acting as substitutional impurity at Ti sites in the anatase TiO2 phase. Substitution of Fe at Ti sites was also confirmed by Raman spectra. The paramagnetic nature of the Ti1- x Fe x O2 samples was further investigated using density functional theory calculations of their electronic band structure and density of states. Finally, the photocatalytic activity of the Fe-doped TiO2 samples was studied by investigating their photocatalytic decomposition of methylene blue.

  3. Enhanced photocatalytic properties of nanoclustered P-doped TiO2 films deposited by advanced atmospheric plasma jet.

    PubMed

    Seo, Hyung-Kee; Elliott, C Michael; Ansari, S G

    2012-09-01

    A facile preparation of P-doped TiO2 nanoclusters onto fluorine-doped tin oxide (FTO) glass by an advanced atmospheric plasma jet (AAP jet) is reported here. Titanium tetrachloride (TiCl4) and phosphorus trichloride (PCl3) were used as precursors. Radio frequencies were used to generate plasma at fix powder with Argon as carrier gas. Films were deposited at 500 degrees C for 10 minutes. For comparison, as-prepared, annealed and deposited at 500 degrees C samples were studied for chemical/physical properties by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Optical properties were studied by using UV-Vis spectroscopy which indicated a reduction in optical band with P-doping. The rhodamine B (Rh-B) degradation by P-doped TiO2 deposited at 500 degrees C showed enhanced degradation efficiency than that of annealed TiO2. The suggested deposition method appears to be suitable for the synthesis of photocatalyst with proper control over dopants.

  4. 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).

  5. Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components.

    PubMed

    Wang, Dawei; Li, Yi; Li Puma, Gianluca; Wang, Chao; Wang, Peifang; Zhang, Wenlong; Wang, Qing

    2015-03-21

    The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (˙OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×10(8) M(-1) s(-1)) scavenged reactive oxygen species, Cl(-) (k=-5.3×10(8) M(-1) s(-1)) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca(2+) at concentrations higher than 50 mM (k=-1.3×10(9) M(-1) s(-1)) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3(-) (k=6.9×10(8) M(-1) s(-1)) and CO3(2-) (k=3.7×10(8) M(-1) s(-1)) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO˙ generation. Other ubiquitous secondary effluent components including SO4(2-) (k=3.9×10(5) M(-1) s(-1)), NH3(+) (k=3.5×10(5) M(-1) s(-1)) and Na(+) (k=2.6×10(4) M(-1) s(-1)) had negligible effects. 90% of 17-α-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12 min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water.

  6. 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%.

  7. The magnetic characterization of Fe doped TiO2 semiconducting oxide nanoparticles synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    Yeganeh, M.; Shahtahmasebi, N.; Kompany, A.; Karimipour, M.; Razavi, F.; Nasralla, N. H. S.; Šiller, L.

    2017-04-01

    In this work Fe doped TiO2 nanoparticles were synthesized at different Fe/Ti molar ratio from 1% to 5% by sol-gel technique. The post annealing of the samples was carried out at T=400, 600, and 800 °C. HRTEM of the samples revealed that the mean size of the nanoparticles increases from about 8 nm to about 100 nm as the annealing temperature increased. SQUID magnetometry of 1% and 5% Fe doped TiO2 has shown mixed ferromagnetic and paramagnetic phases within the crystal while ferromagnetic order with Tc about 350 K was only observed in 5% Fe:TiO2 sample annealed at T=800 °C. The oxygen vacancy mediated ferromagnetic (FM) interaction could be responsible for the observed FM.

  8. Properties of a three-dimensionally ordered macro-mesoporous carbon-doped TiO2 composite catalyst

    NASA Astrophysics Data System (ADS)

    Sui, Wubin; Zheng, Jingtang; Pittman, Charles U.; Bensalah, Nasr; Wu, Mingbo; Zhao, Yucui

    2014-11-01

    This study aimed to develop an effective, environmentally benign composite catalyst composed of carbon materials and titanium dioxide (TiO2). Carbon-doped titanium dioxide (C-TiO2) was prepared by coating TiO2 onto macro-mesoporous carbon (MMC). The structure, morphology and surface chemistry states of the C-TiO2 were characterized by XRD, TEM, XPS, UV-vis and FTIR. The photocatalytic activity of C-TiO2 was evaluated based on the decomposition of an aqueous methyl orange solution in visible light. C-TiO2 significantly improved photocatalytic activity. A possible mechanism for the improvement of the photocatalytic activity of C-TiO2 in visible light was proposed. The results of the analysis suggested that MMC played key roles as the support, absorbent, location of photo-generated electron transfer, and carbon-doping source during methyl orange photodegradation.

  9. Preparation and characterization of Fe3+-doped TiO2 on fly ash cenospheres for photocatalytic application

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Li, Qin; Wang, Wei; Li, Ying; Zhai, Jianping

    2011-02-01

    Fe3+-doped TiO2 film deposited on fly ash cenosphere (Fe-TiO2/FAC) was successfully synthesized by the sol-gel method. These fresh photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). The XRD results showed that Fe element can maintain metastable anatase phase of TiO2, and effect of temperature showed rutile phase appears in 650 °C for 0.01% Fe-TiO2/FAC. The SEM analysis revealed the Fe-TiO2 films on the surface of a fly ash cenosphere with a thickness of 2 μm. The absorption threshold of Fe-TiO2/FACs shifted to a longer wavelength compared to the photocatalyst without Fe3+-doping in the UV-vis absorption spectra. The photocatalytic activity and kinetics of Fe-TiO2/FAC with varying the iron content and the calcination temperatures were investigated by measuring the photodegradation of methyl blue (MB) during visible light irradiation. Compared with TiO2/FAC and Fe3+-doped TiO2 powder (Fe-TiO2), the degradation ratio using Fe-TiO2/FAC increased by 33% and 30%, respectively, and the best calcined temperature was 450 °C and the optimum doping of Fe/Ti molar ratio was 0.01%. The Fe-TiO2/FAC particles can float in water due to the low density of FAC in favor of phase separation to recover these photocatalyst after the reaction, and the recovery test shows that calcination contributes to regaining photocatalytic activity of Fe-TiO2/FAC photocatalyst.

  10. 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.

  11. Modification of Charge Trapping at Particle/Particle Interfaces by Electrochemical Hydrogen Doping of Nanocrystalline TiO2

    PubMed Central

    2016-01-01

    Particle/particle interfaces play a crucial role in the functionality and performance of nanocrystalline materials such as mesoporous metal oxide electrodes. Defects at these interfaces are known to impede charge separation via slow-down of transport and increase of charge recombination, but can be passivated via electrochemical doping (i.e., incorporation of electron/proton pairs), leading to transient but large enhancement of photoelectrode performance. Although this process is technologically very relevant, it is still poorly understood. Here we report on the electrochemical characterization and the theoretical modeling of electron traps in nanocrystalline rutile TiO2 films. Significant changes in the electrochemical response of porous films consisting of a random network of TiO2 particles are observed upon the electrochemical accumulation of electron/proton pairs. The reversible shift of a capacitive peak in the voltammetric profile of the electrode is assigned to an energetic modification of trap states at particle/particle interfaces. This hypothesis is supported by first-principles theoretical calculations on a TiO2 grain boundary, providing a simple model for particle/particle interfaces. In particular, it is shown how protons readily segregate to the grain boundary (being up to 0.6 eV more stable than in the TiO2 bulk), modifying its structure and electron-trapping properties. The presence of hydrogen at the grain boundary increases the average depth of traps while at the same time reducing their number compared to the undoped situation. This provides an explanation for the transient enhancement of the photoelectrocatalytic activity toward methanol photooxidation which is observed following electrochemical hydrogen doping of rutile TiO2 nanoparticle electrodes. PMID:27960341

  12. Modification of Charge Trapping at Particle/Particle Interfaces by Electrochemical Hydrogen Doping of Nanocrystalline TiO2.

    PubMed

    Jiménez, Juan M; Bourret, Gilles R; Berger, Thomas; McKenna, Keith P

    2016-12-14

    Particle/particle interfaces play a crucial role in the functionality and performance of nanocrystalline materials such as mesoporous metal oxide electrodes. Defects at these interfaces are known to impede charge separation via slow-down of transport and increase of charge recombination, but can be passivated via electrochemical doping (i.e., incorporation of electron/proton pairs), leading to transient but large enhancement of photoelectrode performance. Although this process is technologically very relevant, it is still poorly understood. Here we report on the electrochemical characterization and the theoretical modeling of electron traps in nanocrystalline rutile TiO2 films. Significant changes in the electrochemical response of porous films consisting of a random network of TiO2 particles are observed upon the electrochemical accumulation of electron/proton pairs. The reversible shift of a capacitive peak in the voltammetric profile of the electrode is assigned to an energetic modification of trap states at particle/particle interfaces. This hypothesis is supported by first-principles theoretical calculations on a TiO2 grain boundary, providing a simple model for particle/particle interfaces. In particular, it is shown how protons readily segregate to the grain boundary (being up to 0.6 eV more stable than in the TiO2 bulk), modifying its structure and electron-trapping properties. The presence of hydrogen at the grain boundary increases the average depth of traps while at the same time reducing their number compared to the undoped situation. This provides an explanation for the transient enhancement of the photoelectrocatalytic activity toward methanol photooxidation which is observed following electrochemical hydrogen doping of rutile TiO2 nanoparticle electrodes.

  13. 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.

  14. Time effects on the stability of the induced defects in TiO2 nanoparticles doped by different nitrogen sources

    NASA Astrophysics Data System (ADS)

    Spadavecchia, F.; Ardizzone, S.; Cappelletti, G.; Oliva, C.; Cappelli, S.

    2012-12-01

    N-doped TiO2 samples are claimed to be the most promising among the so-called second-generation photocatalysts, but their success in photocatalysis is still under debate. In this study, N-doped TiO2 nanocrystals are obtained by a simple, quick, and effortless procedure, starting from titanium alkoxide as the precursor for the sol-gel route, with the N source being either inorganic (NH3) or organic (triethylamine, urea). Structural, morphological, and optical characterizations are compared with electron paramagnetic resonance (EPR) data to give an integrated picture of such materials. No literature data on the "aging" features in the dry state of the fresh calcined samples on the EPR and diffuse reflectance spectra (DRS) measurements are reported. Our N-doped TiO2 powders show different stabilities of paramagnetic and optical signals. The photocatalytic activity is tested, toward the degradation of ethanol in aqueous media, under both visible and UV irradiation, in this latter case resembling the same trend of the paramagnetic species decay.

  15. Photocatalytic degradation of Orange G on nitrogen-doped TiO2 catalysts under visible light and sunlight irradiation.

    PubMed

    Sun, Jianhui; Qiao, Liping; Sun, Shengpeng; Wang, Guoliang

    2008-06-30

    In this paper, the degradation of an azo dye Orange G (OG) on nitrogen-doped TiO2 photocatalysts has been investigated under visible light and sunlight irradiation. Under visible light irradiation, the doped TiO2 nanocatalysts demonstrated higher activity than the commercial Dugussa P25 TiO2, allowing more efficient utilization of solar light, while under sunlight, P25 showed higher photocatalytic activity. According to the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectra analyses, it was found that both the nanosized anatase structure and the appearance of new absorption band in the visible region caused by nitrogen doping were responsible for the significant enhancement of OG degradation under visible light. In addition, the photosensitized oxidation mechanism originated from OG itself was also considered contributing to the higher visible-light-induced degradation efficiency. The effect of the initial pH of the solution and the dosage of hydrogen peroxide under different light sources was also investigated. Under visible light and sunlight, the optimal solution pH was both 2.0, while the optimal dosage of H2O2 was 5.0 and 15.0 mmol/l, respectively.

  16. 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

  17. Synthesis and characterisations of Au-nanoparticle-doped TiO2 and CdO thin films

    NASA Astrophysics Data System (ADS)

    Gültekin, Aytaç; Karanfil, Gamze; Özel, Faruk; Kuş, Mahmut; Say, Ridvan; Sönmezoğlu, Savaş

    2014-06-01

    In the present study, pure and gold nanoparticle (Au NP)-doped titanium dioxide (TiO2) and cadmium oxide (CdO) thin film were prepared by the sol-gel method, and the effect of Au NP doping on the optical, structural and morphological properties of these thin films was investigated. The prepared thin films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible-near infrared (UV-Vis-NIR) spectra. While the optical band increases from 3.62 to 3.73 for TiO2 thin films, it decreases from 2.20 to 1.55 for CdO thin films with increasing Au doping concentration. Analysis of XRD indicates that the intensities of peaks of the crystalline phase have increased with the increasing Au NP concentrations in all thin films. SEM images demonstrate that the surface morphologies of the samples were affected by the incorporation of Au NPs. Consequently, the most significant results of the present study are that the Au NPs can be used to modify the optical, structural and morphological properties of TiO2 and CdO thin films.

  18. Growth, differentiation, and migration of osteoblasts on transparent Ni doped TiO2 thin films deposited on borosilicate glass.

    PubMed

    Dhayal, Marshal; Kapoor, Renu; Sistla, Pavana Goury; Kant, Chander; Pandey, Ravi Ranjan; Govind; Saini, Krishan Kumar; Pande, Gopal

    2012-05-01

    A simple and cost effective dip coating method was used to deposit thin films of amorphous (AM) or anatase (AN) titanium dioxide (TiO(2)) on borosilicate glass substrates, either with or without prior doping of TiO(2) with nickel (Ni) cations by a specially designed sol gel technique. The objective of the study was to compare the physicochemical and biological properties of these films and assess their use in orthopedic implants or for in vitro cell biological studies. Analytical techniques such as XRD and XPS, in combination with ATR-FTIR and SEM revealed that only AN films, prepared by controlled heating up to 450°C, irrespective of prior doping with Ni, contained significant crystalline structures of variable morphologies. This observation could be linked to the carbon and oxygen contents and the availability of functional groups in the films. Cell biological studies revealed that Ni doping of TiO(2) in both AM and AN films improved the adhesion, spreading, proliferation, differentiation, and migration of MC3T3 cells. Our studies provide a new approach to prepare optically transparent metal surfaces, with tunable physicochemical properties, which could be suitable for eliciting optimal osteoinductive cell responses and permit the detailed in vitro cell biological studies of osteoblasts.

  19. Hydrogen-doped Brookite TiO2 Nanobullets Array as a Novel Photoanode for Efficient Solar Water Splitting

    PubMed Central

    Choi, Mingi; Lee, June Ho; Jang, Youn Jeong; Kim, Donghyung; Lee, Jae Sung; Jang, Hyun Myung; Yong, Kijung

    2016-01-01

    As a representative photocatalyst for photoelectrochemical solar water splitting, TiO2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO2, rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H+. which has the minimum formation energy among three states of hydrogen (H+. H0, and H−). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO2. PMID:27782198

  20. Hydrogen-doped Brookite TiO2 Nanobullets Array as a Novel Photoanode for Efficient Solar Water Splitting

    NASA Astrophysics Data System (ADS)

    Choi, Mingi; Lee, June Ho; Jang, Youn Jeong; Kim, Donghyung; Lee, Jae Sung; Jang, Hyun Myung; Yong, Kijung

    2016-10-01

    As a representative photocatalyst for photoelectrochemical solar water splitting, TiO2 has been intensively studied but most researches have focused on the rutile and anatsase phases because brookite, another important crystalline polymorph of TiO2, rarely exists in nature and is difficult to synthesize. In this work, hydrogen doped brookite (H:brookite) nanobullet arrays were synthesized via a well-designed solution reaction for the first time. H:brookite shows highly improved PEC properties with excellent stability, enhanced photocurrent, and significantly high Faradaic efficiency for overall solar water splitting. To support the experimental data, ab initio density functional theory calculations were also conducted. At the interstitial doping site that has minimum formation energy, the hydrogen atoms act as shallow donors and exist as H+. which has the minimum formation energy among three states of hydrogen (H+. H0, and H‑). The calculated density of states of H:brookite shows a narrowed bandgap and an increased electron density compared to the pristine brookite. The combined experimental and theoretical results provide frameworks for the exploration of the PEC properties of doped brookite and extend our knowledge regarding the undiscovered properties of brookite of TiO2.

  1. 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.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  5. 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.

  6. Determination of TiO2 and AgTiO2 Nanoparticles in Artemia salina: Toxicity, Morphological Changes, Uptake and Depuration.

    PubMed

    Ozkan, Yesim; Altinok, Ilhan; Ilhan, Hasan; Sokmen, Munevver

    2016-01-01

    In this study, aquatic stability and toxic effects of TiO2 and AgTiO2 nanoparticles (NPs) were investigated on Artemia salina nauplii. AgTiO2 was found to be more toxic to nauplii compared to TiO2. The mortality rate in nauplii increased significantly with increasing concentrations and duration of exposure. TiO2 eliminations ranged between 27.8% and 96.5% at 50 and 1 mg/L TiO2 exposed to nauplii, respectively. Accumulation and elimination of Ag in AgTiO2 exposed nauplii were similar except at 1 mg/L AgTiO2. When NPs were mixed with water, the hydrodynamic dimensions of NPs significantly increased because of aggregation in saltwater but NP size decreased over time. NPs-exposed nauplii showed changes in eye formation, enlargement of the intestine, malformations in the outer shell and antennae loss were also observed. Since accumulation and toxicity of AgTiO2 NPs was higher than TiO2 alone, inevitably release of AgTiO2 into aqueous environments can cause ecological risks.

  7. Bismuth-doped ordered mesoporous TiO2: visible-light catalyst for simultaneous degradation of phenol and chromium.

    PubMed

    Sajjad, Shamaila; Leghari, Sajjad A K; Chen, Feng; Zhang, Jinlong

    2010-12-10

    A controllable and reproducible synthesis of highly ordered two-dimensional hexagonal mesoporous, crystalline bismuth-doped TiO(2) nanocomposites with variable Bi ratios is reported here. Analyses by transmission electron microscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy reveal that the well-ordered mesostructure is doped with Bi, which exists as Bi(3+) and Bi((3+x+)). The Bi-doped mesoporous TiO(2) (ms-TiO(2)) samples exhibit improved photocatalytic activities for simultaneous phenol oxidation and chromium reduction in aqueous suspension under visible and UV light over the pure ms-TiO(2), P-25, and conventional Bi-doped titania. The high catalytic activity is due to both the unique structural characteristics and the Bi doping. This new material extends the spectral response from UV to the visible region, and reduces electron-hole recombination, which renders the 2.0% Bi-doped ms-TiO(2) photocatalyst highly responsive to visible light.

  8. Preparation of Pd-loaded La-doped TiO2 nanotubes and investigation of their photocatalytic activity under visible light

    NASA Astrophysics Data System (ADS)

    Zong, Lanlan; Li, Qiuye; Zhang, Jiwei; Wang, Xiaodong; Yang, Jianjun

    2013-11-01

    Orthorhombic titanic acid nanotubes (TAN) have large BET surface area and small-diameter one-dimensional nanotubular morphology, so they can work as a good supporter and a precursor of TiO2. However, in our former research, we found that calcination of TAN to anatase TiO2 would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La2O3) to keep the nanotubular morphology of TiO2, and obtained the anatase TiO2 nanotubes with large BET surface area. For improving the photocatalytic activity, Pd nanoparticles were loaded as the electron traps on the surface of La-doped TiO2 by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N2 adsorption-desorption isotherms measurement. Their photocatalytic activities were evaluated by the removal of propylene under visible light irradiation ( λ ≥ 420 nm). The results showed that the photocatalytic activity of Pd-loaded La-doped TiO2 nanotubes improved effectively compared with that of La-doped TiO2 and pure TiO2.

  9. Role of dopant concentration, crystal phase and particle size on microbial inactivation of Cu-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Sahu, Manoranjan; Wu, Bing; Zhu, Liying; Jacobson, Craig; Wang, Wei-Ning; Jones, Kristen; Goyal, Yogesh; Tang, Yinjie J.; Biswas, Pratim

    2011-10-01

    The properties of Cu-doped TiO2 nanoparticles (NPs) were independently controlled in a flame aerosol reactor by varying the molar feed ratios of the precursors, and by optimizing temperature and time history in the flame. The effect of the physico-chemical properties (dopant concentration, crystal phase and particle size) of Cu-doped TiO2 nanoparticles on inactivation of Mycobacterium smegmatis (a model pathogenic bacterium) was investigated under three light conditions (complete dark, fluorescent light and UV light). The survival rate of M. smegmatis (in a minimal salt medium for 2 h) exposed to the NPs varied depending on the light irradiation conditions as well as the dopant concentrations. In dark conditions, pristine TiO2 showed insignificant microbial inactivation, but inactivation increased with increasing dopant concentration. Under fluorescent light illumination, no significant effect was observed for TiO2. However, when TiO2 was doped with copper, inactivation increased with dopant concentration, reaching more than 90% (>3 wt% dopant). Enhanced microbial inactivation by TiO2 NPs was observed only under UV light. When TiO2 NPs were doped with copper, their inactivation potential was promoted and the UV-resistant cells were reduced by over 99%. In addition, the microbial inactivation potential of NPs was also crystal-phase-and size-dependent under all three light conditions. A lower ratio of anatase phase and smaller sizes of Cu-doped TiO2 NPs resulted in decreased bacterial survival. The increased inactivation potential of doped TiO2 NPs is possibly due to both enhanced photocatalytic reactions and leached copper ions.

  10. Role of dopant concentration, crystal phase and particle size on microbial inactivation of Cu-doped TiO2 nanoparticles.

    PubMed

    Sahu, Manoranjan; Wu, Bing; Zhu, Liying; Jacobson, Craig; Wang, Wei-Ning; Jones, Kristen; Goyal, Yogesh; Tang, Yinjie J; Biswas, Pratim

    2011-10-14

    The properties of Cu-doped TiO(2) nanoparticles (NPs) were independently controlled in a flame aerosol reactor by varying the molar feed ratios of the precursors, and by optimizing temperature and time history in the flame. The effect of the physico-chemical properties (dopant concentration, crystal phase and particle size) of Cu-doped TiO(2) nanoparticles on inactivation of Mycobacterium smegmatis (a model pathogenic bacterium) was investigated under three light conditions (complete dark, fluorescent light and UV light). The survival rate of M. smegmatis (in a minimal salt medium for 2 h) exposed to the NPs varied depending on the light irradiation conditions as well as the dopant concentrations. In dark conditions, pristine TiO(2) showed insignificant microbial inactivation, but inactivation increased with increasing dopant concentration. Under fluorescent light illumination, no significant effect was observed for TiO(2). However, when TiO(2) was doped with copper, inactivation increased with dopant concentration, reaching more than 90% (>3 wt% dopant). Enhanced microbial inactivation by TiO(2) NPs was observed only under UV light. When TiO(2) NPs were doped with copper, their inactivation potential was promoted and the UV-resistant cells were reduced by over 99%. In addition, the microbial inactivation potential of NPs was also crystal-phase-and size-dependent under all three light conditions. A lower ratio of anatase phase and smaller sizes of Cu-doped TiO(2) NPs resulted in decreased bacterial survival. The increased inactivation potential of doped TiO(2) NPs is possibly due to both enhanced photocatalytic reactions and leached copper ions.

  11. 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

    2016-07-22

    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.

  12. 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.

  13. 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

  14. Highly Visible Light Activity of Nitrogen Doped TiO2 Prepared by Sol-Gel Approach

    NASA Astrophysics Data System (ADS)

    Than, Le Dien; Luong, Ngo Sy; Ngo, Vu Dinh; Tien, Nguyen Manh; Dung, Ta Ngoc; Nghia, Nguyen Manh; Loc, Nguyen Thai; Thu, Vu Thi; Lam, Tran Dai

    2017-01-01

    A simple approach was explored to prepare N-doped anatase TiO2 nanoparticles (N-TiO2 NPs) from titanium chloride (TiCl4) and ammonia (NH3) via sol-gel method. The effects of important process parameters such as calcination temperatures, NH3/TiCl4 molar ratio ( R N) on crystallite size, structure, phase transformation, and photocatalytic activity of titanium dioxide (TiO2) were thoroughly investigated. The as-prepared samples were characterized by ultraviolet-visible spectroscopy, x-ray diffraction, transmission electron microscopy, energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The photocatalytic activity of the samples was evaluated upon the degradation of methylene blue aqueous solution under visible-light irradiation. The results demonstrated that both calcination temperatures and NH3/TiCl4 molar ratios had significant impacts on the formation of crystallite nanostructures, physicochemical, as well as catalytic properties of the obtained TiO2. Under the studied conditions, calcination temperature of 600°C and NH3/TiCl4 molar ratio of 4.2 produced N-TiO2 with the best crystallinity and photocatalytic activity. The high visible light activity of the N-TiO2 nanomaterials was ascribed to the interstitial nitrogen atoms within TiO2 lattice units. These findings could provide a practical pathway capable of large-scale production of a visible light-active N-TiO2 photocatalyst.

  15. 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

  16. Spectrophotometric studies of visible light induced photocatalytic degradation of methyl orange using phthalocyanine-modified Fe-doped TiO2 nanocrystals.

    PubMed

    Mesgari, Zohreh; Gharagozlou, Mehrnaz; Khosravi, Alireza; Gharanjig, Kamaladin

    2012-06-15

    In this paper, preparation and visible light induced photocatalytic activity of phthalocyanine-modified Fe-doped TiO(2) nanocrystals (Pc/Fe-TiO(2)) with different Fe doping content (0, 0.05, 0.5 and 3.0 mol% Fe) as photocatalysts for the degradation of methyl orange have been reported. The study carried out using XRD, FT-IR, EDX, BET, DRS, UV-Vis, SEM and TEM techniques. Results revealed that modified TiO(2) nanocrystals possessed only the anatase phase with crystal sizes of about 10-23 nm and high surface areas of 2.8-37.3 m(2)/g. It can be seen phthalocyanine and Fe(3+) ion exist in photocatalysts based on analysis of FT-IR and EDX. The doping amount of Fe remarkably affects the activity of modified TiO(2) nanocrystals as catalysts. The 0.5 mol% Fe doping exhibited enhanced photocatalytic activity in this work. It was found that phthalocyanine and Fe induced a shift in the energy band gap to lower energies, which changes from 3.26 to 2.26 eV for pure TiO(2) and Pc/3% Fe-TiO(2) nanocrystals, respectively. Results of the degradation of methyl orange revealed that modified TiO(2) nanocrystals showed much more photocatalytic activity than pure TiO(2) under visible light which makes the applicability of TiO(2) photocatalysts even more versatile.

  17. 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.

  18. Visible light absorption ability and photocatalytic oxidation activity of various interstitial N-doped TiO2 prepared from different nitrogen dopants.

    PubMed

    Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat; Seraphin, Supapan

    2009-08-30

    Nitrogen-doped TiO(2) was developed to enable photocatalytic reactions using the visible range of the solar spectrum. This work reports on the synthesis, characterisation and kinetic study of interstitial N-doped TiO(2) prepared by the sol-gel method using three different types of nitrogen dopants: diethanolamine, triethylamine and urea. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-visible spectroscopy were used to analyse the titania. Different interstitial N-doped TiO(2) properties, such as absorption ability in the UV-visible light region, redshift in adsorption edge, good crystallisation and composition ratio of titania structures (anatase and rutile) could be obtained from different nitrogen dopants. Amongst investigated nitrogen precursors, diethanolamine provided the highest visible light absorption ability of interstitial N-doped TiO(2) with the smallest energy bandgap and the smallest anatase crystal size, resulting in the highest efficiency in 2-chlorophenol degradation. The photocatalytic activity of all N-doped TiO(2) can be arranged in the following order: TiO(2)/diethanolamine>TiO(2)/triethylamine>TiO(2)/urea>un-doped TiO(2). The initial rate of 2-chlorophenol degradation using the interstitial N-doped TiO(2) with diethanolamine was 0.59 mg/L-min and the kinetic constant was 2.34 x 10(-2)min(-1) with a half-life of 98 min. In all cases, hydroquinone was detected as a major intermediate in the degradation of 2-chlorophenol.

  19. Improved visible light photocatalytic activity of fluorine and nitrogen co-doped TiO2 with tunable nanoparticle size

    NASA Astrophysics Data System (ADS)

    Cheng, Junyang; Chen, Jin; Lin, Wei; Liu, Yandong; Kong, Yan

    2015-03-01

    Fluorine and nitrogen co-doped TiO2 (F-N-TiO2) photocatalysts with enhanced photocatalytic activities were facilely synthesized by a simple one-step hydrothermal method using Ti(SO4)2 as an economical precursor, and hydrofluoric acid and ammonia as F and N source, respectively. The structure, morphology, and optical properties of produced nanoparticles were characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FT-IR) methods. The synergistic effects of F and N doping were systematically examined by changing the molar ratio of F/N. Compared with the un-doped F or N mono-doped TiO2, the co-doped samples exhibited significantly improved photocatalytic performance due to their synergistic effects under visible light. It was shown that F dopant promoted the crystal growth and crystallinity of samples, while N dopant hindered it to some extent, which resulted in the tunable particle size of obtained F-N-TiO2 materials. The effects of F and N dopants on the enhanced photocatalytic activity of modified TiO2 materials were also discussed. The degradation rate of methylene blue (MB) was achieved at 97.31% after 5 h reaction under visible light over the optimized sample of FN3.5T. The materials also showed excellent stability according to the recycling tests of the photodegradation of MB.

  20. Structure and Property of Nano-TiO2 Doped with Ag+ Membrane Photocatalyst.

    PubMed

    Liu, Fang; He, Ting; Cao, Qingyun; Xu, Yuehua; Liu, Wei; Zhou, Wuyi

    2015-04-01

    Highly transparent silver incorporated titania (Ag/TiO2) composite nanomembranes were fabricated by a simple, reproducible dip-coating process on ceramic substrates. The obtained membrane samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDX), X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the Ag/TiO2 nanomembranes was assessed by the degradation of methylene blue under visible light irradiation. Compared with pure TiO2 nanomembranes, no significant shift in the TiO2 crystal structure was detected after doping with silver ions. The results from the SEM and EDX analyses showed that homogeneous spherical silver nanoparticles were produced and scattered on the surface of the TiO2 nanomembrane that was coated on the surface of the ceramic substrates. The doping with silver ions could effectively improve the photocatalytic activity of TiO2 under visible light irradiation. The Ag/TiO2 composite nanomembrane also exhibited improved hydrophilicity compared to that of a pure TiO2 nanomembrane.

  1. Characterization of the thin layer photocatalysts TiO2 and V2O5- and Fe2O3- doped TiO2 prepared by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Loc Luu, Cam; Nguyen, Quoc Tuan; Thoang Ho, Si; Nguyen, Tri

    2013-09-01

    The catalysts TiO2 and TiO2 doped with Fe and V were prepared using the sol-gel method. TiO2-modified samples were obtained in the form of a thick film on pyrex glass sticks and tubes and were used as catalysts in the gas phase photo-oxidation of p-xylene. The physico-chemical characteristics of the catalysts were determined using the methods of Brunauer-Emmett-Teller adsorption, x-ray diffraction, and infrared, ultraviolet and visible and Raman spectroscopies. The experimental results show that the introduction of V did not expand the region of light absorption, but slightly reduced the size of the TiO2 particles, and reduced the number of OH-groups, which should decrease the photocatalytic activity and efficiency of the obtained catalysts compared to those of pure TiO2. The Fe-doped TiO2 samples, in contrast, are characterized by an extension of the spectrum of photon absorption to the visible region with wavenumbers λ up to 464 nm and the values of their band gap energy decreased to lower quantities (up to 2.67 eV), therefore they should have higher catalytic activity and conversion efficiency of p-xylene in the visible region than the original sample. For these catalysts, a combined utilization of radiation by ultraviolet (λ = 365 nm) and visible (λ = 470 nm) light increased the activity and the yield in p-xylene conversion by a factor of around 2-3, as well as making these quantities more stable in comparison with those of TiO2-P25 Degussa.

  2. 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.

  3. Fe3+-Doped TiO2 Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity

    PubMed Central

    Yu, Jiangdong; Wu, Zhi; Gong, Cheng; Xiao, Wang; Sun, Lan; Lin, Changjian

    2016-01-01

    Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and related electrochemical techniques. XPS results demonstrated that Fe3+ ions were successfully doped into TiO2 nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO2 nanotube arrays (TNTs). The results showed that Fe-TNTs grown on low concentration (0.5 wt %–1 wt % Fe) Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB) aqueous solution was significantly higher than that of TNTs. PMID:28335234

  4. 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.

  5. Preparation and characterization of PVA-I complex doped mesoporous TiO2 by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Shi, Qian; Jiang, Caiyun; Wang, Yuping; Yang, Weiben; Yang, Chun

    2013-05-01

    Polyvinyl alcohol [PVA]-iodine complex doped mesoporous TiO2 (PIT) and iodine doped (IT) catalysts were prepared by hydrothermal method, using tetrabutyl titanate as precursor, potassium iodate and iodine as iodine sources. The as-prepared PIT and IT catalysts were characterized by UV-vis, XRD, FESEM, BET, TG/DTA, XPS and photoluminescence (PL) spectroscopy. Production of rad OH radicals on the surface of photocatalyst was detected by the PL technique using terephthalic acid as a probe molecule. The influences of calcinated temperature on the structure and properties of the catalysts were investigated. The photocatalytic activity of catalysts was evaluated through photocatalytic decolorization of methylene blue (MB) aqueous solution. The results showed that PIT samples were anatase mesoporous TiO2 and their iodine content and mesoporous structure were influenced by calcinated temperature. Particle size of PIT samples was smaller than that of IT as a result of the PVA skeleton and regular structure. Because of the complexation of iodine and PVA, thermostability of iodine is improved and the amount of iodine in PIT calcinated at 200 °C (PIT-200) is higher than that of IT calcinated at same temperature. Light absorption range and intensity of PIT-200 has been greatly improved due to the synergy of iodine and carbon. The efficiency of photocatalysis for MB is greatly improved with TiO2 modified by PVA-I complex under simulated sun light irradiation.

  6. Effect of photocatalytic reduction of carbon dioxide by N-Zr co-doped nano TiO2.

    PubMed

    Zhang, Ru; Wang, Li; Kang, Zhuo; Li, Qiang; Pan, Huixian

    2017-01-04

    Modified sol-gel method was adopted to prepare TiO2, Zr-TiO2 and N/Zr-TiO2 composite catalyst. The as-synthesized photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunner- Emmet- Teller measurement and UV-Vis diffuse reflectance spectroscopy. And the photocatalytic performance toward CO2 reduction was evaluated under ultraviolet light. The catalyst particles were demonstrated in the nanometer level size. When N and Zr are co-doped, on the one hand, Ti(4+) can be replaced by Zr4 +, which leads to lattice distortion and inhibits electron-hole recombination. On the other hand, N enters into TiO2 lattice gap to form O-Ti-N bond structure, and partial Ti(4+) are reduced to Ti(3+). Compared with pristine TiO2, the specific surface area and the band gap of N/Zr-TiO2 were improved and reduced, respectively. The N and Zr synergistically contribute to the obviously strengthened absorption intensity in visible region, as well as significantly improved photocatalytic activity. In the gas phase reactor, when the calcination temperature was 550°C, 0.125N/0.25Zr-TiO2 composite performed the highest photocatalytic activity UV irradiation for 8 h, and the corresponding CH4 yield was 11.837 µmol/g, which was 87.8% higher than that of pristine TiO2. For the visible light, the CH4 yield was 9.003 µmol/g after 8 h irradiation, which was 83.9% higher than that of pristine TiO2.

  7. A self-cleaning porous TiO2-Ag core-shell nanocomposite material for surface-enhanced Raman scattering.

    PubMed

    Zou, Xiaoxin; Silva, Rafael; Huang, Xiaoxi; Al-Sharab, Jafar F; Asefa, Tewodros

    2013-01-14

    A porous TiO(2)-Ag core-shell nanocomposite material with a large surface area was synthesized by in situ hydrolyzation of Sn(2+)-grafted titanium glycolate microspheres in the presence of Ag(+) ions. The as-prepared nanocomposite material was shown to serve as an efficient self-cleaning surface-enhanced Raman scattering (SERS) substrate.

  8. Tuning the band gap of mesoporous Zr-doped TiO2 for effective degradation of pesticide quinalphos.

    PubMed

    Goswami, Pallabi; Ganguli, Jatindra Nath

    2013-10-28

    This paper has focused on the synthesis and modification of TiO2 nanomaterial via an acid modified sol-gel process. ZrOCl2 was used as a source of Zr for doping titania. The nanomaterials were characterized by electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption isotherms, UV-visible diffuse reflectance spectroscopy, etc. Changes in the band gap of the synthesized nanomaterials were studied with respect to the dopant amount, and the performance of the synthesized nanomaterials was evaluated as a photocatalyst to degrade pesticide quinalphos in aqueous solution under UV light. Anatase TiO2 nanocrystallites with an average size of ca. 8-11 nm were obtained depending on the amount of dopant. The results showed that the amount of dopant significantly altered the band gap as well as the surface properties of the hybrid nanomaterials which resulted in high photocatalytic activity.

  9. Carrier-mediated Kondo effect and Hall mobility by electrolyte gating in slightly doped anatase TiO2 films

    NASA Astrophysics Data System (ADS)

    Han, Yin-Long; Luo, Zhong-Zhong; Li, Cheng-Jian; Shen, Sheng-Chun; Qu, Guo-Liang; Xiong, Chang-Min; Dou, Rui-Fen; He, Lin; Nie, Jia-Cai

    2014-11-01

    Carrier density (ns) is a crucial parameter that governs the properties of correlated oxides, so the field-effect approach is an ideal tool to investigate the novel physics of the system. Here, the carrier-mediated transport of slightly doped anatase TiO2 epitaxial films were studied by electric double layer transistor (EDLT) gating. The ns has been increased hugely, and concomitantly, the channels of anatase TiO2 films undergo an insulator-metal transition with a decrease in resistivity by almost three orders of magnitude. More fascinating, the Kondo effect depends very strongly on ns, and the Hall mobility could be enhanced about one order of magnitude with increasing ns. This study shows that EDLT gating is a powerful method to stimulate and mediate novel phenomena of correlated oxides.

  10. 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.

  11. Double-doped TiO2 nanoparticles as an efficient visible-light-active photocatalyst and antibacterial agent under solar simulated light

    NASA Astrophysics Data System (ADS)

    Ashkarran, Ali Akbar; Hamidinezhad, Habib; Haddadi, Hedayat; Mahmoudi, Morteza

    2014-05-01

    Silver and nitrogen doped TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet-visible absorption spectroscopy (UV-vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO2 NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO2 NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO2 NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from UV to the visible-light region.

  12. 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.

  13. Facile route to fabricate carbon-doped TiO2 nanoparticles and its mechanism of enhanced visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Huang, Gui-Fang; Li, Dongfeng; Zhou, Bing-Xin; Chang, Shengli; Pan, Anlian; Huang, Wei-Qing

    2016-12-01

    High-efficiency photocatalysis requires wide photoresponse range and effective separation of photogenerated charges to fully utilize solar energy. Exploring the simple and cheap methods to synthesize efficient photocatalysts is still a challenging issue. Herein, we report a facile and simple room-temperature hydrolysis method using glucose as carbon source to prepare visible light-active C-doped TiO2 photocatalyst. This approach features low-cost, reliable, and easily upscalable. It is found that C atoms have been incorporated into the interstitial position of anatase TiO2 lattice and distributed homogeneously throughout the surface of TiO2 nanoparticles. The appropriate C doping can greatly improve the separation of photogenerated electron-hole pairs in C-doped TiO2. The C-doped TiO2 samples exhibit enhanced photocatalytic activity with the degradation efficiency under UV and visible light irradiation, which is much faster than that of pure TiO2. The mechanism of the enhanced photocatalytic activity is discussed in detail, which is confirmed by using different scavengers. The work provides a simple and useful way to prepare C-doped wide-gap semiconductors with enhanced photocatalytic activity.

  14. Ag Nanoparticle–Functionalized Open-Ended Freestanding TiO2 Nanotube Arrays with a Scattering Layer for Improved Energy Conversion Efficiency in Dye-Sensitized Solar Cells

    PubMed Central

    Rho, Won-Yeop; Chun, Myeung-Hwan; Kim, Ho-Sub; Kim, Hyung-Mo; Suh, Jung Sang; Jun, Bong-Hyun

    2016-01-01

    Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO2 nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO2 NPs to create a scattering effect in order to improve energy conversion efficiency. Compared to closed-ended freestanding TiO2 nanotube array–based DSSCs without Ag or large TiO2 NPs, the energy conversion efficiency of closed-ended DSSCs improved by 9.21% (actual efficiency, from 5.86% to 6.40%) with Ag NPs, 6.48% (actual efficiency, from 5.86% to 6.24%) with TiO2 NPs, and 14.50% (actual efficiency, from 5.86% to 6.71%) with both Ag NPs and TiO2 NPs. By introducing Ag NPs and/or large TiO2 NPs to open-ended freestanding TiO2 nanotube array–based DSSCs, the energy conversion efficiency was improved by 9.15% (actual efficiency, from 6.12% to 6.68%) with Ag NPs and 8.17% (actual efficiency, from 6.12% to 6.62%) with TiO2 NPs, and by 15.20% (actual efficiency, from 6.12% to 7.05%) with both Ag NPs and TiO2 NPs. Moreover, compared to closed-ended freestanding TiO2 nanotube arrays, the energy conversion efficiency of open-ended freestanding TiO2 nanotube arrays increased from 6.71% to 7.05%. We demonstrate that each component—Ag NPs, TiO2 NPs, and open-ended freestanding TiO2 nanotube arrays—enhanced the energy conversion efficiency, and the use of a combination of all components in DSSCs resulted in the highest energy conversion efficiency. PMID:28335245

  15. The antibacterial and hydrophilic properties of silver-doped TiO2 thin films using sol-gel method

    NASA Astrophysics Data System (ADS)

    Wang, Xuemin; Hou, Xinggang; Luan, Weijiang; Li, Dejun; Yao, Kun

    2012-08-01

    Ag-TiO2 composite thin films were deposited on glass slides by sol-gel spin coating technique. The surface structure, chemical components and transmittance spectra were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectrophotometer. The TiO2 thin films with silver molar ratio from 0 to 10% were tested for its antibacterial property by using Escherichia coliform (E. coli) under irradiation of UV light. The concentration of E. coli was evaluated by plating technique. The influences of different molar ratio of Ag on hydrophilicity and long-term durability of the films were also investigated by measuring the water contact angle. The results showed that the antibacterial ability was significantly improved by increasing silver content comparing with pure TiO2 thin film, and the best molar ratio of Ag was 5%. While the hydrophilicity of films increased with increasing silver content, and the best molar ratio of Ag was 1%.

  16. Photo-electro-catalytic performance of highly ordered nitrogen doped TiO2 nanotubes array photoanode

    NASA Astrophysics Data System (ADS)

    Aritonang, Anthoni B.; Surahman, Hedi; Krisnandi, Yuni K.; Gunlazuardi, Jarnuzi

    2017-02-01

    Highly ordered nitrogen doped TiO2 nanotube arrays (N-TNTAs) were synthesized via a one step anodization method at 40 V for 1 hour, in the electrolyte containing ammonium fluoride (NH4F), water and triethylamine solution, followed calcination under N2 atmosphere at 450oC for 3 h. The obtained samples were characterized by means of FE-SEM image showed that the N-TNTs are in a highly ordered array, having inner diameters, wall thickness, tube length of 65 nm, 30 nm and 900 nm, respectively. The X-ray diffraction (XRD) patterns of N-TNTAs and undoped TiO2 nanotubes arrays (TNTAs) are identical consists of anatase phase, which suggests that the doping of N does not affect the crystalline structure. X-ray photoelectron spectroscopy (XPS), revealed that N atom was incorporated into the lattice of a TiO2 nanotube array film. The infrared spectra, showed a new peak at 1240 cm-1 may indicate the incorporation of N into the lattice of TiO2 through substituting O atoms, in the form of ∼N-Ti-O∼. A red shift of the absorption edge toward the visible region of N-TNTAs are observed by diffuse reflectance spectroscopy (DRS), which is corresponding to a band gap of 2.8 eV. The photo-electro-catalytic (PEC) degradation efficiency toward methylene blue solution under visible light illumination of the N-TNTAs electrode was 89%, in which the rate constant of N-TNTAs electrode was 8 times better compared to that the undoped TNTAs photo-electrode.

  17. The origin of ferromagnetism of Co-doped TiO2 nanoparticles: Experiments and theory investigation

    NASA Astrophysics Data System (ADS)

    Zhang, Suyin; Zhou, Zhongpo; Xiong, Rui; Shi, Jing; Lu, Zhihong; Wang, Haiying

    2016-11-01

    A series of Ti1-xCoxO2-δ (x = 0.01, 0.03, 0.05, 0.07) nanoparticles were synthesized by sol-gel method. The X-ray diffraction, transmission electron microscopy, Raman analysis and X-ray photoelectron spectroscopy ruled out the signatures of Ti3+, Co-clusters or any other oxides of Co. The ferromagnetic behavior was clearly observed at room temperature in doped samples with saturation magnetization (Ms) of the order of 0.008-0.035 emu/g depending on doping concentrations. The saturation magnetization is found to be increased with the Co contents increasing from 1% to 7%. From the plot of the M-T curve, we obtain the Tc as ˜515 K for 5% Co-doped TiO2. Oxygen vacancies were detected from the photoluminescence (PL) measurement. Magnetic properties analyses and PL analyses showed that oxygen vacancies probably played a major role in ferromagnetism of the Ti1-xCoxO2 system with Co substituting for Ti. The first-principles calculation was performed to investigate the magnetic properties of Co-doped TiO2 nanoparticles. It can be found that the major magnetic moment is from the 3d electron of Co. The experiment results are consistent with the first-principles calculation. The ferromagnetism derived from the spin-split of O-2p and Co-3d electron states caused by p-d orbit hybridization.

  18. Synthesis and Photocatalytic Properties of Ce-Doped TiO2 Nanotube Arrays via Anodic Oxidation

    NASA Astrophysics Data System (ADS)

    Kong, Junhan; Wang, Yongqian; Sun, Qimeng; Meng, Dawei

    2017-03-01

    Ce-doped TiO2 nanotube arrays (TNAs) were prepared successfully through one-step anodic oxidation methods. The structural and morphological features of the TNAs were monitored by x-ray diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. Ultraviolet-visible light absorption spectra showed the light absorption performances of TiO2 nanotubes in both ultraviolet (UV) and visible light regions. Also, the photocatalytic activities of these samples were measured by the photodegradation rate of methylene blue (MB). The result indicated that doping a moderate amount of cerium ions into TNAs increased the absorption of both ultraviolet light and visible light obviously. However, the excess amount of doping ions would destroy the tubular structure severely and decrease the specific surface area of TNAs sharply. It could directly lead to the decreasing of photocatalytic activitity of TNAs. Furthermore, the best photodegradation rate of the Ce-doped TNAs on MB reached to 95.6%, which had a huge improvement comparing with pure TNAs.

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

    NASA Astrophysics Data System (ADS)

    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 8 at.%) of zinc. The results of X-ray diffraction (XRD) had shown the presence of anatase peak with a strong orientation along (1 0 1) plane at 8 at.% 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 8 at.% of Zn-doped TiO2 with the particle size and decrease in surface roughness. The emission at 398 nm was observed at the 8 at.% 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.

  20. 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

    2015-03-05

    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.

  1. 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.

  2. Effects of Ag doping on the photocatalytic disinfection of E. coli in bioaerosol by Ag-TiO₂/GF under visible light.

    PubMed

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-08-15

    Ag doped TiO2/glass fibers (Ag-TiO2/GF) were prepared and used for photocatalytic disinfection of Escherichia coli (E. coli) in an indoor air environment. The prepared photocatalysts were characterized using scanning electron microscope (SEM) for morphology, X-ray diffraction (XRD) for microstructure, UV-Visible diffuse reflectance spectra (DRS) for optical properties and X-ray photoelectron spectroscopy (XPS) to determine elemental state. The optimized weight fraction of TiO2 in the TiO2/glass fiber (TiO2/GF) was 3%. The silver content in Ag/TiO2 was altered from 1% to 10% to investigate the optimal ratio of Ag doped on the TiO2/GF for the photocatalytic disinfection of E. coli. Doped Ag enhanced the electron-hole separation as well as charge transfer efficiency between the valance band and the conduction band of TiO2. The generated electron-hole pairs reacted with water and molecular oxygen to form strong oxidative radicals, which participated in the oxidation of organic components of E. coli, resulting in bacterial death. The photocatalytic disinfection activity under visible light increased with the increase in silver content up to 7.5% and then decreased slightly with further increasing Ag content. Among the three humidity conditions used in this study (40±5%, 60±5%, 80±5%), the highest disinfection ratio of E. coli by the photocatalytic system was observed in the intermediate humidity level followed by the high humidity level. Using the 7.5% Ag-TiO2/GF and the intermediate level of humidity (60±5%), the highest disinfection ratio and disinfection capacity of E. coli were 93.53% and 26 (CFU/s cm(2)), respectively.

  3. 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.

  4. Effects of oxygen vacancy on 3d transition-metal doped anatase TiO2: First principles calculations

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    In this work, systematic study of the formation energy, crystalline and electronic structures of 3d transition metal (Sc, V, Cr, Mn, Fe, Co and Ni) doped anatase TiO2 specimens with and without oxygen vacancy has been carried out by the first principles calculations. The impurity states located at the band gaps enhance the visible light absorption, and the oxygen vacancy result in the EF move into the CB for some doped systems, which induce the Ti3+ ions and promote the separation of photogenerated carriers. Doping and oxygen vacancy can change the hybrid strength and MP value of TMsbnd O bonding which has the approximately linearly with the band gap.

  5. Enhanced photocatalytic degradation of dye under visible light on mesoporous microspheres by defects in manganese- and nitrogen-co-doped TiO2

    NASA Astrophysics Data System (ADS)

    Feng, Lu; Jiang, Heng; Zou, Mingming; Xiong, Fengqiang; Ganeshraja, Ayyakannu Sundaram; Pervaiz, Erum; Liu, Yinan; Zou, Shunying; Yang, Minghui

    2016-09-01

    Manganese- and nitrogen-co-doped mesoporous TiO2 microsphere photocatalysts are prepared by a simple sol-gel method with controllable sizes in the range of 400-500 nm and high surface area of 112 m2 g-1. Manganous acetate is the Mn source, and ammonia gas is the nitrogen source used. The dopants are found to be uniformly distributed in the TiO2 matrix. Interestingly, in (Mn,N)-co-doped TiO2, we observe an effective indirect band gap of 2.58 eV. (Mn,N)-co-doped mesoporous TiO2 microspheres show higher photocatalytic activity than Mn-TiO2 microspheres under visible light irradiation. Among the samples reported in this work, 0.2 at.% Mn doping and 500 °C 2-h nitriding condition give the highest photocatalytic activity. The observed photocatalytic activity in the (Mn,N)-co-doped TiO2 is attributed to the contribution from improved absorption due to trap levels of Mn, oxygen vacancies and N doping.

  6. Synthesis, characterization and photocatalytic evaluation of visible light activated C-doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Guanglong; Han, Changseok; Pelaez, Miguel; Zhu, Duanwei; Liao, Shuijiao; Likodimos, Vlassis; Ioannidis, Nikolaos; Kontos, Athanassios G.; Falaras, Polycarpos; Dunlop, Patrick S. M.; Byrne, J. Anthony; Dionysiou, Dionysios D.

    2012-07-01

    We have demonstrated heterogeneous photocatalytic degradation of microcystin-LR (MC-LR) by visible light activated carbon doped TiO2 (C-TiO2) nanoparticles, synthesized by a modified sol-gel route based on the self-assembly technique exploiting oleic acid as a pore directing agent and carbon source. The C-TiO2 nanoparticles crystallize in anatase phase despite the low calcination temperature of 350 °C and exhibit a highly porous structure that can be optimized by tuning the concentration of the oleic acid surfactant. The carbon modified nanomaterials exhibited enhanced absorption in the broad visible light region together with an apparent red shift in the optical absorption edge by 0.5 eV (2.69 eV), compared to the 3.18 eV of reference anatase TiO2. Carbon species were identified by x-ray photoelectron spectroscopy analysis through the formation of both Ti-C and C-O bonds, indicative of substitution of carbon for oxygen atoms and the formation of carbonates, respectively. Electron paramagnetic resonance spectroscopy revealed the formation of two carbon related paramagnetic centers in C-TiO2, whose intensity was markedly enhanced under visible light illumination, pointing to the formation of localized states within the anatase band gap, following carbon doping. The photocatalytic activity of C-TiO2 nanomaterials was evaluated for the degradation of MC-LR at pH 3.0 under visible light (λ > 420 nm) irradiation. The doped materials showed a higher MC-LR degradation rate than reference TiO2, behavior that is attributed to the incorporation of carbon into the titania lattice.

  7. Optical properties analysis of Ta-doped TiO2 thin films on LaAlO3 substrates

    NASA Astrophysics Data System (ADS)

    Nurfani, Eka; Sutjahja, Inge M.; Winata, Toto; Rusydi, Andrivo; Darma, Yudi

    2015-09-01

    We study optical properties of Ta-doped TiO2 thin film on LaAlO3 substrate using spectroscopy ellipsometry (SE) analysis at energy range of 0.5 - 6.5 eV. Room temperature SE data for Ψ (amplitude ratio) and Δ (phase difference) between p- and s- polarized light waves are taken with multiple incident angles at several spots on the samples. Here, absorption coefficient has been extracted from SE measurements at photon incident angle of 70° for different Ta concentration (0.01, 0.4, and 5 at. %). Multilayer modelling is performed which takes into account reflections at each interface through Fresnel coefficients to obtain reasonably well the fitting of Ψ and Δ data simultaneously. As the results, we estimate that film thickness increases by increasing Ta concentration accompanied by the formation of a new electronic structure. By increasing Ta impurities, the blueshift of absorption coefficient (α) peaks is observable. This result indicates that TiO2 thin film becomes optically resistive by introducing Ta doping. Schematic model of interband transition inTiO2:Ta will be proposed base on obtained optical properties. This study enables us to predict the role of Ta doping on the electronic and optical band structures of TiO2 thin film. Due to a processing error by AIP Publishing, an incorrect version of the above article was published on 30 September 2015 that omitted the name of author Toto Winata. AIP Publishing apologizes for this error. All online versions of the article were corrected on 7 October 2015. The author names and affiliations appear correctly above.

  8. Synthesis, characterization and photocatalytic evaluation of visible light activated C-doped TiO2 nanoparticles.

    PubMed

    Liu, Guanglong; Han, Changseok; Pelaez, Miguel; Zhu, Duanwei; Liao, Shuijiao; Likodimos, Vlassis; Ioannidis, Nikolaos; Kontos, Athanassios G; Falaras, Polycarpos; Dunlop, Patrick S M; Byrne, J Anthony; Dionysiou, Dionysios D

    2012-07-27

    We have demonstrated heterogeneous photocatalytic degradation of microcystin-LR (MC-LR) by visible light activated carbon doped TiO(2) (C-TiO(2)) nanoparticles, synthesized by a modified sol-gel route based on the self-assembly technique exploiting oleic acid as a pore directing agent and carbon source. The C-TiO(2) nanoparticles crystallize in anatase phase despite the low calcination temperature of 350 °C and exhibit a highly porous structure that can be optimized by tuning the concentration of the oleic acid surfactant. The carbon modified nanomaterials exhibited enhanced absorption in the broad visible light region together with an apparent red shift in the optical absorption edge by 0.5 eV (2.69 eV), compared to the 3.18 eV of reference anatase TiO(2). Carbon species were identified by x-ray photoelectron spectroscopy analysis through the formation of both Ti-C and C-O bonds, indicative of substitution of carbon for oxygen atoms and the formation of carbonates, respectively. Electron paramagnetic resonance spectroscopy revealed the formation of two carbon related paramagnetic centers in C-TiO(2), whose intensity was markedly enhanced under visible light illumination, pointing to the formation of localized states within the anatase band gap, following carbon doping. The photocatalytic activity of C-TiO(2) nanomaterials was evaluated for the degradation of MC-LR at pH 3.0 under visible light (λ > 420 nm) irradiation. The doped materials showed a higher MC-LR degradation rate than reference TiO(2), behavior that is attributed to the incorporation of carbon into the titania lattice.

  9. 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.

  10. Photoluminescence and Raman spectroscopy studies of Eu3+-doped rutile TiO2 nanocrystals at high pressures

    NASA Astrophysics Data System (ADS)

    Zeng, Q. G.; Ding, Z. J.; Lei, B. F.; Sheng, Y. Q.; Zhang, Z. M.

    2012-09-01

    Nanocrystal samples (particle size about 90 nm) of Eu3+-doped rutile titanium dioxide (TiO2) nanocrystals (rutile Eu3+/TiO2 nanocrystals) were synthesized by the sol-gel method with hydrothermal treatment. The pressure effect on photoluminescence (PL) and Raman spectra of the rutile Eu3+/TiO2 nanocrystals was investigated with a diamond anvil cell under hydrostatic pressure condition. Raman spectra of the samples at high pressures indicated that the critical pressure for the transition from the rutile phase to a new baddeleyite-type phase was between 10 and 14.2 GPa. The position of Raman bands shifted to high wavenumbers and the PL intensity of 5D 0→7F 2 transition of Eu3+ decreased down to zero with the increase of pressure before the phase transition occurred. After releasing the pressure, the rutile phase was not recovered and a α-PbO2-type phase was observed at ambient pressure.

  11. [Preparation of Fe(3+) -doped TiO2 nanometer thin film and study on its photocatalytic performances].

    PubMed

    Zheng, Huai-Li; Zhang, Jun-Hua; Li, Hong; Li, Zhi-Liang

    2005-12-01

    In the present paper, Fe(3+) -doped TiO2 nanometer thin films were prepared on the surface of glass by sol-gel processing. Effects of ferro-dopant, PEG addition levels, and the number of layers on transmittance and photocatalytic degradability were then respectively investigated. Meanwhile some relative mechanisms of the effects were discussed. It was shown that the photocatalytic activity of the films could be promoted by ferro-dopant, and the rate of degradation was 1.38 times that without ferro-dopant. Moreover, the optimal photocatalytic activity and transmittance were obtained by adding 0.1 g (0.13 wt%) PEG to the sol precursor. In addition, the TiO2 nanometer thin films with 2 to 5 layers all had better transmittance, and the best one for practical application had two layers. The glass coated with TiO2 nanometer thin film shows potential and wide application value in construction industry, lamps manufacture, urban lighting engineering, etc. because of its remarkable abilities of self-purification, economy in energy, and environmental protection.

  12. 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.

  13. Insight into visible light-driven photocatalytic degradation of diesel oil by doped TiO2-PS floating composites.

    PubMed

    Wang, Xin; Wang, Wei; Wang, Xuejiang; Zhao, Jianfu; Zhang, Jing; Song, Jingke

    2016-09-01

    TiO2-pearlstone (PS) floatable photocatalysts were synthesized using a facile sol-gel method and confirmed by XRD, N2 adsorption-desorption, SEM, EDX, TEM, FT-IR, XPS, and UV-vis DRS measurements. It has been found that the photocatalysts composed of anatase TiO2 deposited on the surface of PS and formed mesoporous structure. By N or B/N doping, the band gap of the photocatalyst has been narrowed. The obtained floatable photocatalysts can be applied to solar light-driven remediation of oil-contaminated water. Diesel oil was chosen as the model pollutant to evaluate the photocatalytic activity. The results showed B/N-TiO2-PS exhibited the highest photocatalytic activity for diesel oil under visible light irradiation, which is 48 % removal rate for 9 h. The reaction rate constant k of B/N-TiO2-PS is 0.08423 h(-1), which is four times larger than that of pure TiO2-PS. Moreover, the characteristic of floatable makes the photocatalysts easier to separate and reuse, which showed great potential for practical applications in the field of environmental cleanup and solar energy conversion.

  14. Theoretical and photo-electrochemical studies of surface plasmon induced visible light absorption of Ag loaded TiO2 nanotubes for water splitting

    NASA Astrophysics Data System (ADS)

    Gross, P. A.; Javahiraly, N.; Geraldini Sabat, N.; Cottineau, T.; Savinova, E. R.; Keller, V.

    2016-10-01

    Vertically aligned TiO2 nanotubes (TiO2-NTs), obtained by anodization in organic electrolyte, are decorated with 15 nm Ag nanoparticles prepared by a micro-wave assisted polyol synthesis. The Ag/TiO2 system is characterized by electronic microscopies in order to build a Finite Differential Time Domain (FDTD) model to simulate the interaction of light with the system. By combining UV-visible spectroscopy and FDTD simulations, the observed red shift in the surface plasmon resonance wavelength of the Ag nanoparticles, deposited on TiO2, is explained. The Ag/TiO2-NT system is used as photoanode in a photoelectrochemical water splitting setup and shows an increasing Incident Photon to Current Conversion Efficiency (IPCE) in the visible light domain with an increasing amount of deposited Ag. The spectral position of this activity enhancement coincides with the one expected from the FDTD calculations for the surface plasmon resonance of the Ag nanoparticles deposited on TiO2.

  15. Synthesis of magnetically separable Ag3PO4/TiO2/Fe3O4 heterostructure with enhanced photocatalytic performance under visible light for photoinactivation of bacteria.

    PubMed

    Xu, Jing-Wen; Gao, Zhi-Da; Han, Kun; Liu, Yongmin; Song, Yan-Yan

    2014-09-10

    Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4 nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4 can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2 interfaces cause considerable morphological changes in the microorganism's cells and lead to the death of the bacteria.

  16. 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.

  17. 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

    2013-09-03

    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.

  18. A novel approach for the synthesis of visible-light-active nanocrystalline N-doped TiO2 photocatalytic hydrosol

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Xiu; Jiang, Peng; Shao, Wei-Na; Zhang, Jun; Cao, Wen-Bin

    2014-07-01

    A visible-light-active nitrogen doped nanocrystalline titanium dioxide (N-TiO2) hydrosol was prepared by precipitation-peptization method and following with hydrothermal crystallization at 110 °C holding for 6 h. XPS results show that nitrogen ions have been doped into the TiO2 lattice successfully and the UV-Vis absorption spectra indicate that the light absorption edge of the N-doped TiO2 has been red-shifted into visible light region. The photocatalytic performance of the N-doped TiO2 thin film prepared from the synthesized hydrosol was evaluated by photodegrading the gaseous formaldehyde (HCHO) under visible light irradiation. The photodegradation ratio of HCHO reached up to 90% within 24 h and the degradation ratio was stable for ten degradation cycles, indicating the prepared hydrosol has good reusable performance in photodegrading gaseous pollutants.

  19. 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.

  20. 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.

  1. Photodecolorization of Rhodamine B on tungsten-doped TiO2/activated carbon under visible-light irradiation.

    PubMed

    Li, Youji; Zhou, Xiaoming; Chen, Wei; Li, Leiyong; Zen, Mengxiong; Qin, Shidong; Sun, Shuguo

    2012-08-15

    Tungsten-doped TiO(2)/activated carbon catalysts have been prepared by a supercritical-pretreatment-assisted sol-gel process. The structural features of the photocatalysts have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/Vis diffuse-reflectance spectroscopy (DRS), electron dispersive X-ray (EDX), photoluminescence spectroscopy, and Brunauer-Emmett-Teller (BET) analysis. The results revealed that a W-TiO(2) layer was coated on the AC surface, and had higher surface area and smaller crystallite size than TiO(2)/AC obtained by a similar route. The W dopant was responsible for narrowing the band gap of TiO(2) and shifting its optical response from the ultraviolet (UV) to the visible-light region. The photocatalytic performances of the supported catalysts have been evaluated for the degradation of Rhodamine B (RhB) solution under visible-light irradiation. Compared with bulk W-TiO(2), the photoactivity was obviously enhanced when it was coated onto AC. In addition, it was found that the reactivity showed a significant relationship with the amount of W dopant, and the photoactivity order of the catalysts from weak to strong showed good agreement with their PL intensities. The effects of TiO(2) content, tungsten ion content, catalyst amount, pH, and initial RhB concentration have been examined as operational parameters. The photocatalytic reactions followed pseudo-first-order kinetics and are discussed in terms of the Langmuir-Hinshelwood model.

  2. Antibacterial properties and human gingival fibroblast cell compatibility of TiO2/Ag compound coatings and ZnO films on titanium-based material.

    PubMed

    Chang, Yin-Yu; Lai, Chih-Ho; Hsu, Jui-Ting; Tang, Chih-Hsin; Liao, Wan-Chuen; Huang, Heng-Li

    2012-02-01

    Titanium (Ti)-based materials are widely used in biomedical implant components and are applied successfully in various types of bone-anchored reconstructions. However, in dental implants the Ti materials contact not only bone but also gingival tissues, and are partially exposed to the oral cavity that includes bacteria. This study used titania and silver (TiO(2)/Ag) compound coatings and zinc oxide (ZnO) films to enhance the antibacterial activity of the Ti-based implant. The hydrophobicity of each sample was examined by measuring the contact angle. Streptococcus mutans and human gingival fibroblast (HGF) was cultured on the coated samples, and the antibacterial effects and cell compatibility were determined using a Syto9 fluorescence staining and MTT methods. For the TiO(2)/Ag samples, depositing Ag on the plate at a higher power (which increased the proportion of Ag) increased the contact angle and the hydrophobicity. The bacterial count was lowest for the 50 W TiO(2)/Ag sample, which contained 5.9% Ag. The contact angles of the ZnO samples did not show the same tendency. The antibacterial effect was higher on ZnO-coated samples since bacterial count was threefold lower on ZnO samples as compared to control samples (Ti plate). From the MTT assay test, the mean optical density values for TiO(2)/Ag-coated samples after 72 h of HGF adhesion were similar to the value obtained from the uncoated Ti. However, biocompatibility was lower on ZnO films than in control samples. Conclusively, the antibacterial activity was higher but the cell compatibility was lower on ZnO films than on TiO(2)/Ag coatings.

  3. High-rate performance of Ti3+ self-doped TiO2 prepared by imidazole reduction for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Seok, Dong-il; Wu, Mihye; Shim, Kwang Bo; Kang, Yongku; Jung, Ha-Kyun

    2016-10-01

    Ti3+ self-doped TiO2 nanoparticles were prepared via a simple imidazole reduction process and developed as an anode material for Li-ion batteries. Introducing the Ti3+-state on TiO2 nanoparticles resulted in superior rate performances that the capacity retention of 88% at 50 C. The enhanced electrochemical performances were attributed to the resulting lower internal resistance and improved electronic conductivity, based on galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses.

  4. Chemisorption of CH2O on N-doped TiO2 anatase nanoparticle as modified nanostructure media: A DFT study

    NASA Astrophysics Data System (ADS)

    Abbasi, Amirali; Sardroodi, Jaber Jahanbin; Ebrahimzadeh, Alireza Rastkar

    2016-12-01

    The structural and electronic properties of N-doped TiO2 anatase nanoparticles and their effects on the adsorption of formaldehyde molecule have been investigated using the density functional theory computations. Given the need to better understand the behavior of the adsorbed CH2O molecule on the anatase nanoparticle, we report results of density functional theory studies of the N-doped nanoparticles, as well as complex systems consisting of the CH2O molecule bound to a TiO2 nanoparticle. N-doped nanoparticle was obtained by substitution of nitrogen atom of TiO2 instead of oxygen atom. Adsorptions of the CH2O molecule on the dangling oxygen atom, twofold coordinated oxygen atom and doped nitrogen atom sites of the pristine and N-doped anatase nanoparticles were investigated. The results presented include structural parameters such as adsorption energies, bond lengths and bond angles and electronic properties such as density of states, spin distribution densities and molecular orbitals. It was found that the adsorption of the CH2O molecule on the dangling oxygen of considered N-doped TiO2 anatase nanoparticles is energetically more favorable than the adsorption on the undoped ones. It means a more stable configuration compared to the undoped nanoparticle adsorption, but not as stable as the CH2O adsorption on the doped nitrogen site of N-doped nanoparticles.

  5. 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.

  6. Nanostructured N-doped TiO2 marigold flowers for an efficient solar hydrogen production from H2S

    NASA Astrophysics Data System (ADS)

    Chaudhari, Nilima S.; Warule, Sambhaji S.; Dhanmane, Sushil A.; Kulkarni, Milind V.; Valant, Matjaz; Kale, Bharat B.

    2013-09-01

    Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and production of hydrogen under solar light. The maximum hydrogen evolution obtained is higher than other known N-TiO2 systems. It is noteworthy that photohydrogen production using the unique marigold flowers of N-TiO2 from abundant H2S under solar light is hitherto unattempted. The proposed synthesis method can also be utilized to design other hierarchical nanostructured N-doped metal oxides.Nitrogen-doped TiO2 nanostructures in the form of marigold flowers have been synthesized for the first time using a facile solvothermal method. The structural analysis has shown that such an N-doped TiO2 system crystallizes in the anatase structure. The optical absorption spectra have clearly shown the shift in the absorption edge towards the visible-light range, which indicates successful nitrogen doping. The nitrogen doping has been further confirmed by photoluminescence and photoemission spectroscopy. Microscopy studies have shown the thin nanosheets (petals) of N-TiO2 with a thickness of ~2-3 nm, assembled in the form of the marigold flower with a high surface area (224 m2 g-1). The N-TiO2 nanostructure with marigold flowers is an efficient photocatalyst for the decomposition of H2S and

  7. Liquid-phase non-thermal plasma-prepared N-doped TiO(2) for azo dye degradation with the catalyst separation system by ceramic membranes.

    PubMed

    Cheng, Hsu-Hui; Chen, Shiao-Shing; Cheng, Yi-Wen; Tseng, Wei-Lun; Wang, Yi-Hui

    2010-01-01

    This study strived to improve the photocatalytic activity by using liquid-phase non-thermal plasma (LPNTP) technology for preparing N-doping TiO(2) as well as to separate/recover the N-dope TiO(2) particles by using ceramic ultrafiltration membrane process. The yellow color N-doped TiO(2) photocatalysts, obtained through the LPNTP process, were characterized with UV-Vis spectroscopy, X-ray diffraction (XRD), and electron spectroscopy for chemical analysis (ESCA). The UV-Vis spectrum of N-doped TiO(2) showed that the absorption band was shifted to 439 nm and the band gap was reduced to 2.82 eV. The structure analysis of XRD spectra showed that the peak positions and the crystal structure remained unchanged as anatase after plasma-treating at 13.5 W for 40 min. The photocatalytic activity of N-doped TiO(2) was evaluated by azo dyes under visible light, and 63% of them was degraded after 16 hours in a continuous-flow photocatalytic system. For membrane separation/recover system, the recovery efficiency reached 99.5% after the ultrafiltration had been carried out for 90 min, and the result indicated that the photocatalyst was able to be separated/recovered completely.

  8. Degradation of selected industrial dyes using Mg-doped TiO2 polyscales under natural sun light as an alternative driving energy

    NASA Astrophysics Data System (ADS)

    Shivaraju, H. P.; Midhun, G.; Anil Kumar, K. M.; Pallavi, S.; Pallavi, N.; Behzad, Shahmoradi

    2017-03-01

    Designing photocatalytic materials with modified functionalities for the utilization of renewable energy sources as an alternative driving energy has attracted much attention in the area of sustainable wastewater treatment applications. Catalyst-assisted advanced oxidation process is an emerging treatment technology for organic pollutants and toxicants in industrial wastewater. Preparation of visible-light-responsive photocatalyst such as Mg-doped TiO2 polyscales was carried out under mild sol-gel technique. Mg-doped TiO2 polyscales were characterized by powder XRD, SEM, FTIR, and optical and photocatalytic activity techniques. The Mg-doped TiO2 showed a mixed phase of anatase and rutile with an excellent crystallinity, structural elucidations, polyscales morphology, consequent shifting of bandgap energy and adequate photocatalytic activities under visible range of light. Mg-doped TiO2 polyscales were investigated for their efficiencies in the degradation of most commonly used industrial dyes in the real-time textile wastewater. Mg-doped TiO2 polyscales showed excellent photocatalytic degradation efficiency in both model industrial dyes (65-95%) and textile wastewater (92%) under natural sunlight as an alternative and renewable driving energy.

  9. N-Doped TiO2 Nanobelts with Coexposed (001) and (101) Facets and Their Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Production.

    PubMed

    Sun, Shuchao; Gao, Peng; Yang, Yurong; Yang, Piaoping; Chen, Yujin; Wang, Yanbo

    2016-07-20

    To narrow the band gap (3.2 eV) of TiO2 and extend its practical applicability under sunlight, the doping with nonmetal elements has been used to tune TiO2 electronic structure. However, the doping also brings new recombination centers among the photoinduced charge carriers, which results in a quantum efficiency loss accordingly. It has been proved that the {101} facets of anatase TiO2 are beneficial to generating and transmitting more reductive electrons to promote the H2-evolution in the photoreduction reaction, and the {001} facets exhibit a higher photoreactivity to accelerate the reaction involved of photogenerated hole. Thus, it was considered by us that using the surface heterojunction composed of both {001} and {101} facets may depress the disadvantage of N doping. Fortunately, we successfully synthesized anatase N-doped TiO2 nanobelts with a surface heterojunction of coexposed (101) and (001) facets. As expected, it realized the charge pairs' spatial separation and showed higher photocatalytic activity under a visible-light ray: a hydrogen generation rate of 670 μmol h(-1) g(-1) (much higher than others reported previously in literature of N-doped TiO2 nanobelts).

  10. Mesoporous TiO2@N-doped carbon composite nanospheres synthesized by the direct carbonization of surfactants after sol-gel process for superior lithium storage.

    PubMed

    Zhu, Hongwei; Jing, Yunke; Pal, Manas; Liu, Yupu; Liu, Yang; Wang, Jinxiu; Zhang, Fan; Zhao, Dongyuan

    2017-01-26

    Here, we report mesoporous TiO2@N-doped carbon composite nanospheres synthesized via a double-surfactant-assisted assembly sol-gel process followed by sequential carbonization of surfactants under a N2 atmosphere. The resulting TiO2@N-doped C composite nanospheres are composed of uniformly distributed TiO2 nanocrystals with a diameter of ∼8 nm coated by a N-doped carbon layer that was formed by surfactants. Moreover, a large number of connected mesopores were observed in the nanospheres after high-temperature carbonization treatment. The synthesized nanospheres possess a large specific surface area (∼120 m(2) g(-1)) and a large pore size (4-40 nm), with a well-defined spherical structure and a diameter in the nanoscale range. As an anode material for lithium-ion batteries (LIB), the mesoporous composite nanospheres delivered a reversible capacity of ∼117 mA h g(-1) after 2000 cycles at a current rate as high as 10 C, as well as superior rate capability. The N-doped carbon layers greatly improved the overall electrical conductivity of the mesoporous TiO2 nanospheres. This study provides a remarkable synthetic route for the preparation of mesoporous TiO2-based N-doped carbon composite materials as high-performance anode materials in LIBs.

  11. Effects of Fe-doping on the photocatalytic activity of mesoporous TiO2 powders prepared by an ultrasonic method.

    PubMed

    Zhou, Minghua; Yu, Jiaguo; Cheng, Bei

    2006-10-11

    Highly photoactive nanocrystalline mesoporous Fe-doped TiO(2) powders were prepared by the ultrasonic-induced hydrolysis reaction of tetrabutyl titanate (Ti(OC(4)H(9))(4)) in a ferric nitrate aqueous solution (pH 5) without using any templates or surfactants. The as-prepared samples were characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), N(2) adsorption-desorption measurements, UV-visible adsorbance spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by the photocatalytic oxidation of acetone in air. The results showed that all the Fe-doped TiO(2) samples prepared by ultrasonic methods were mesoporous nanocrystalline. A small amount of Fe(3+) ions in TiO(2) powders could obviously enhance their photocatalytic activity. The photocatalytic activity of Fe-doped TiO(2) powders prepared by this method and calcined at 400 degrees C exceeded that of Degussa P25 (P25) by a factor of more than two times at an optimal atomic ratio of Fe to Ti of 0.25. The high activities of the Fe-doped TiO(2) powders could be attributed to the results of the synergetic effects of Fe-doping, large BET specific surface area and small crystallite size.

  12. Photocatalytic activity of La, Y Co-doped TiO2 nanoparticles synthesized by ultrasonic assisted sol-gel method.

    PubMed

    Gao, Hongtao; Liu, Wenchao; Lu, Bing; Liu, Fangfang

    2012-05-01

    Bare TiO2 (T), La-doped TiO2 (LT), Y-doped TiO2 (YT), La, Y co-doped TiO2 (LYT) were successfully prepared by facile ultrasonic assisted sol-gel synthesis using Ti(OC4H9)4 as the precursor. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectra (DRS), and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activities of anatase samples, with the average particle diameters ranging from 14 nm to 21 nm, were evaluated for photodegradation of methyl orange (MO). The XPS results indicated that Y atoms were incorporated into titania lattice, while La atoms existed on the crystal surface. Due to doping, the optical absorption edges of LT, YT, and LYT shifted to the visible light region by 21 nm, 29 nm and 35 nm, respectively. The photocatalytic performances of the doped samples, such as LT, YT and LYT, were much higher than that of bare TiO2 under UV-visible light irradiation. And the photoreactivity efficiency of the LYT was the highest. It indicated that a strong La-Y synergistic interaction appeared to play a decisive role in driving the excellent photocatalytic performance of titania.

  13. Novel three-dimensionally ordered macroporous Fe3+-doped TiO2 photocatalysts for H2 production and degradation applications

    NASA Astrophysics Data System (ADS)

    Yan, Xiaoqing; Xue, Chao; Yang, Bolun; Yang, Guidong

    2017-02-01

    Novel three-dimensionally ordered macroporous (3DOM) Fe3+-doped TiO2 photocatalysts were prepared using a colloidal crystal template method with low-cost raw material including ferric trichloride, isopropanol, tetrabutyl titanate and polymethyl methacrylate. The as-prepared 3DOM Fe3+-doped TiO2 photocatalysts were characterized by various analytical techniques. TEM and SEM results showed that the obtained photocatalysts possess well-ordered macroporous structure in three dimensional orientations. As proved by XPS and EDX analysis that Fe3+ ions have been introduced TiO2 lattice and the doped Fe3+ ions can act as the electron acceptor/donor centers to significantly enhance the electron transfer from the bulk to surface of TiO2, resulting in more electrons could take part in the oxygen reduction process thereby decreasing the recombination rate of photogenerated charges. Meanwhile, the 3DOM architecture with the feature of interfacial chemical reaction active sites and optical absorption active sites is remarkably favorable for the reactant transfer and light trapping in the photoreaction process. As a result, the 3DOM Fe3+-doped TiO2 photocatalysts show the considerably higher photocatalytic activity for decomposition of the Rhodamine B (RhB) and the generation of hydrogen under visible light irradiation due to the synergistic effects of open, interconnected macroporous network and metal ion doping.

  14. TiO2 nanotube arrays modified with Cr-doped SrTiO3 nanocubes for highly efficient hydrogen evolution under visible light.

    PubMed

    Jiao, Zhengbo; Zhang, Yan; Chen, Tao; Dong, Qingsong; Lu, Gongxuan; Bi, Yingpu

    2014-02-24

    In recent decades, solar-driven hydrogen production over semiconductors has attracted tremendous interest owing to the global energy and environmental crisis. Among various semiconductor materials, TiO2 exhibits outstanding photocatalytic properties and has been extensively applied in diverse photocatalytic and photoelectric systems. However, two major drawbacks limit practical applications, namely, high charge-recombination rate and poor visible-light utilization. In this work, heterostructured TiO2 nanotube arrays grafted with Cr-doped SrTiO3 nanocubes were fabricated by simply controlling the kinetics of hydrothermal reactions. It was found that coupling TiO2 nanotube arrays with regular SrTiO3 nanocubes can significantly improve the charge separation. Meanwhile, doping Cr cations into SrTiO3 nanocubes proved to be an effective and feasible approach to enhance remarkably the visible-light response, which was also confirmed by theoretical calculations. As a result, the rate of photoelectrochemical hydrogen evolution of these novel heteronanostructures is an order of magnitude larger than those of TiO2 nanotube arrays and other previously reported SrTiO3 /TiO2 nanocomposites under visible-light irradiation. Furthermore, the as-prepared Cr-doped SrTiO3 /TiO2 heterostructures exhibit excellent durability and stability, which are favorable for practical hydrogen production and photoelectric nanodevices.

  15. 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

  16. 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.

  17. 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.

  18. Synthesis and characterization of TiO 2/Ag/polymer ternary nanoparticles via surface-initiated atom transfer radical polymerization

    NASA Astrophysics Data System (ADS)

    Park, Jung Tae; Koh, Joo Hwan; Seo, Jin Ah; Cho, Yong Soo; Kim, Jong Hak

    2011-08-01

    We report on the novel ternary hybrid materials consisting of semiconductor (TiO 2), metal (Ag) and polymer (poly(oxyethylene methacrylate) (POEM)). First, a hydrophilic polymer, i.e. POEM, was grafted from TiO 2 nanoparticles via the surface-initiated atom transfer radical polymerization (ATRP) technique. These TiO 2-POEM brush nanoparticles were used to template the formation of Ag nanoparticles by introduction of a AgCF 3SO 3 precursor and a NaBH 4 aqueous solution for reduction process. Successful grafting of polymeric chains from the surface of TiO 2 nanoparticles and the in situ formation of Ag nanoparticles within the polymeric chains were confirmed using transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FT-IR spectroscopy also revealed the specific interaction of Ag nanoparticles with the C dbnd O groups of POEM brushes. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the semiconductor, producing ternary hybrid inorganic-organic nanomaterials.

  19. Efficiency Enhancement of Quantum Dot Sensitized TiO2/ZnO Nanorod Arrays Solar Cells by Plasmonic Ag Nanoparticles.

    PubMed

    Zhao, Haifeng; Huang, Fei; Hou, Juan; Liu, Zhiyong; Wu, Qiang; Cao, Haibin; Jing, Qun; Peng, Shanglong; Cao, Guozhong

    2016-10-12

    A high efficiency quantum dot sensitized solar cell (QDSC) based on Ag nanoparticles (NPs) decorated TiO2/ZnO nanorod arrays (NAs) photoelectrode has been constructed. The incorporation of Ag NPs to TiO2/ZnO NAs photoelectrode not only increases light harvesting efficiency and facilitates exciton dissociation but also decreases surface charge recombination and prolongs electron lifetime, which collectively contribute to improving the Jsc of the CdS/CdSe QDs cosensitized solar cells. The direct contact of Ag NPs with TiO2 NPs is undergoing Fermi level alignment; thus, the apparent Fermi level is supposed to trigger an upward shift of more negative potential, which results in an increase the Voc of the QDSCs. As a result, the power conversion efficiency of the QDSCs with Ag NPs decorated TiO2/ZnO NAs photoelectrode reached 5.92%, which is about 22% enhancement of the efficiency for the solar cells without Ag NPs (4.80%).

  20. 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

  1. Fabrication of bidirectionally doped β-Bi2O3/TiO2-NTs with enhanced photocatalysis under visible light irradiation.

    PubMed

    Li, Deyi; Zhang, Yonggang; Zhang, Yalei; Zhou, Xuefei; Guo, Sujin

    2013-08-15

    Stable β-Bi2O3/TiO2-NTs photocatalyst with excellent visible-light-activity is successfully prepared by bidirectional doping. Stake structure of the TiO2-NTs provides a larger specific surface area and makes the contact area between the TiO2-NTs and β-Bi2O3 much larger; The stake structure of TiO2-NTs not only leads to a firmer combination of TiO2-NTs and β-Bi2O3, but also makes them dope one another deeply. The modification of Bi species into TiO2-NTs can form Bi-O-Ti chemical absorption bonds, then a localized impurity level is generated within the band gap. Electrons can be excited and transferred from the Bi(3+) impurity level to the conduction band (CB) of TiO2, similar to narrowing the band-gap of TiO2-NTs, resulting in a red shift of the absorption edge and an enhancement in visible-light activity. During annealing, Bi atoms are partially replaced by Ti atoms. The lattice of β-Bi2O3 is compressed around the Ti impurity, making the lattice dislocate and distort. This dislocation and distortion leads to an increase in the β-Bi2O3 valance band (VB), from 2.02 to 2.28 eV. Accordingly, the weak oxidability of β-Bi2O3 is improved, and its photocatalytic ability is further enhanced. Moreover, this lattice dislocation and distortion changes the Bi-O distances, thus remarkably improving the stability of the β-Bi2O3/TiO2-NTs.

  2. 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.

  3. 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.

  4. 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

    2014-01-16

    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.

  5. Photocatalytic reduction of NO with NH3 using Si-doped TiO2 prepared by hydrothermal method.

    PubMed

    Jin, Ruiben; Wu, Zhongbiao; Liu, Yue; Jiang, Boqiong; Wang, Haiqiang

    2009-01-15

    A series of Si-doped TiO2 (Si/TiO2) photocatalysts supported on woven glass fabric were prepared by hydrothermal method for photocatalytic reduction of NO with NH3. The photocatalytic activity tests were carried out in a continuous Pyrex reactor with the flow rate of 2000mL/min under UV irradiation (luminous flux: 1.1x10(4)lm, irradiated catalyst area: 160cm2). The photocatalysts were characterized by X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectrophotometer, transmission electron microscopy (TEM), photoluminescence (PL) and temperature-programmed desorption (TPD). The experiment results showed that NO conversion on Si/TiO2 at 323K could exceed 60%, which was about 50% higher than that on Degussa P25 and pure TiO2. With the doping of Si, photocatalysts with smaller crystal size, larger surface area and larger pore volume were obtained. It was also found that Ti-O-Si bands were formed on the surface of Si/TiO2 and that the surface hydroxyl concentration was greatly increased. As a result, total acidity and NH3 chemisorption amount were enhanced for Si/TiO2 leading to its photocatalytic activity improvement.

  6. 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

  7. Photochemical degradation of an anionic surfactant by TiO2 nanoparticle doped with C, N in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zamiri, M.; Giahi, M.

    2016-12-01

    Novel C,N-doped TiO2 nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that crystallite size of synthesized C,N-doped TiO2 particles were in nanoscale. UV light photocatalytic studies were carried out using sodium naphthalenesulfonate formaldehyde condensate (SNF) as a model pollutant. The effects of initial concentration of surfactant, catalyst amount, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined. The results indicated that for a solution of 20 mg/L of SNF, almost 98.7% of the substance were removed at pH 4.0 and 0.44 g/L photocatalyst load, with addition of 1 mM K2S2O8 and irradiation time of 90 min. The kinetics of the process was studied, and the photodegradation rate of SNF was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

  8. 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.

  9. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO2

    NASA Astrophysics Data System (ADS)

    Mandal, Suman; Pal, Somnath; Kundu, Asish K.; Menon, Krishnakumar S. R.; Hazarika, Abhijit; Rioult, Maxime; Belkhou, Rachid

    2016-08-01

    Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO2 have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

  10. 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.

  11. 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.

  12. Enhanced photocatalytic activity of S-doped TiO2-ZrO2 nanoparticles under visible-light irradiation.

    PubMed

    Tian, Guohui; Pan, Kai; Fu, Honggang; Jing, Liqiang; Zhou, Wei

    2009-07-30

    Porous nanocrystalline S-doped TiO2-ZrO2 visible-light photocatalysts were prepared through a one-step method. The resulting materials were characterized by X-ray diffraction (XRD), N(2) adsorption-desorption measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), Fourier transform infrared spectra (FT-IR) and electron paramagnetic resonance (ESR). It was found that modification by ZrO2 could effectively inhibit phase transformation, enhance visible-light absorption, and possess more surface hydroxyl groups. The photocatalytic activity of S-doped TiO2-ZrO2 was higher than that of unmodified S-doped TiO2 and Degussa P25. The enhanced photocatalytic activity could be attributed to the higher specific area, smaller crystal size, porous structure and more surface hydroxyl groups in the catalyst.

  13. DFT Investigation on the Electronic and Water Adsorption Properties of Pristine and N-Doped TiO2 Nanotubes for Photocatalytic Water Splitting Applications

    NASA Astrophysics Data System (ADS)

    Enriquez, John Isaac G.; Moreno, Joaquin Lorenzo V.; David, Melanie Y.; Arboleda, Nelson B.; Lin, Ong Hui; Villagracia, Al Rey C.

    2017-02-01

    Experimental studies have shown the production of hydrogen through a photocatalytic water splitting process using a titanium dioxide nanotube (TiO2NT) as a photoelectrode. In this study, a theoretical model of pristine and nitrogen-doped TiO2NT based on a TiO2 anatase (101) surface is presented. Spin unrestricted density functional theory calculations were performed to provide a detailed description of the geometries, electronic properties, and adsorption of water (H2O) on pristine and N-doped TiO2NT. The calculations show that doping with N will improve the photocatalytic properties of TiO2NT in two ways: First, the energy barrier of the dissociation reaction of water into hydroxyl radical and hydrogen atom is reduced; and second, the defect-induced states above the valence band lowers the band gap which will result in enhanced visible-light-driven photoactivity. Based on the position of the Fermi level relative to the defect induced energy levels, an optimal doping concentration of around 1.4% is proposed, which is in good agreement with experimental results. This study provides an atomic/molecular level understanding of the photocatalytic water splitting process and may serve as a groundwork for the rational design of more efficient photocatalysts.

  14. Controllable growth of vertically aligned Bi-doped TiO2 nanorod arrays for all-oxide solid-state DSSCs

    NASA Astrophysics Data System (ADS)

    Asemi, Morteza; Ghanaatshoar, Majid

    2016-09-01

    In this study, vertically aligned Bi-doped TiO2 nanorod arrays as photoanodes were successfully grown on the fluorine-doped tin oxide by hydrothermal method. Structural analysis showed that bismuth was successfully incorporated into the TiO2 lattice at low concentration, but at higher concentration, phase segregation of Bi2O3 in the TiO2 matrix was occurred. TiO2 nanorods with 3 % bismuth concentration had minimum electrical resistivity. As the solid-state electrolyte, Mg-doped CuCrO2 nanoparticles with p-type conductivity were synthesized by sol-gel method. The fabricated all-oxide solid-state dye-sensitized solar cells with Bi-doped TiO2 nanorods displayed better photovoltaic performance due to the presence of Bi. The improved cell performance was correlated with the higher dye loading, slower charge recombination rate and the higher electrical conductivity of the photoanodes. After mechanical pressing, the all-oxide solid-state DSSC exhibited enhanced photovoltaic performance due to the formation of the large neck between adjacent nanoparticles by mechanical sintering. The open-circuit photovoltage decay measurement of the devices and electrical conductivity of the nanoparticles before and after pressing revealed that the mechanical pressing technique reduces charge recombination rate and facilitates electron transport through the interconnected nanoparticles.

  15. 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

  16. 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.

  17. 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.

  18. Photochromic and self-cleaning properties of TiO2-AgCl/TiO2-xCu thin film.

    PubMed

    Sangchay, Weerachai; Sikong, Lek; Kooptarnond, Kalayanee

    2013-02-01

    The TiO2-AgCl/TiO2-xCu thin films were prepared by sol-gel method and dip coated on glass slide. The prepared films were synthesized at the temperature of 400 degrees C for 2 h with a heating rate of 10 degrees C/min. The microstructure and properties of synthesized TiO2-AgCl/TiO2-xCu thin films were characterized by X-ray diffraction, scanning electron microscopy, atomic forced microscope and UV-vis diffuse reflectance spectroscopy. Finally, the hydrophilic property was evaluated by means of contact angle of water droplet on the films. The results show all samples have film thickness in range of 400-500 nm and their surfaces are dense and strong with a large surface area according to the image of atomic forced microscope. It can be noted that TiO2-AgCl/TiO2-5Cu thin films exhibit the highest photochromic (or the lowest capability of light transmittance) at 250-400 nm. The TiO2-AgCl/TiO2-xCu thin films can block UV C, UV B and UV A rays and exhibit self-cleaning effect (small contact angle, 3.9 degrees ) under UV irradiation.

  19. 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.

  20. W-doped TiO2 mesoporous electron transport layer for efficient hole transport material free perovskite solar cells employing carbon counter electrodes

    NASA Astrophysics Data System (ADS)

    Xiao, Yuqing; Cheng, Nian; Kondamareddy, Kiran Kumar; Wang, Changlei; Liu, Pei; Guo, Shishang; Zhao, Xing-Zhong

    2017-02-01

    Doping of TiO2 by metal elements for the scaffold layer of the perovskite solar cells has been proved to be one of the effective methods to improve the power conversion efficiency. In the present work, we report the impact of doping of TiO2 nanoparticles with different amounts of tungsten (W) on the photovoltaic properties of hole transport material free perovskite solar cells (PSCs) that employ carbon counter electrode. Light doping with W (less than 1000 ppm) improves the power conversion efficiencies (PCEs) of solar cells by promoting the electron conductivity in the TiO2 layer which facilitates electron transfer and collection. With the incorporation of W, average efficiency of PSCs is increased from 9.1% for the un-doped samples to 10.53% for the 1000 ppm W-doped samples, mainly originates from the increase of short circuit current density and fill factor. Our champion cell exhibits an impressive PCE of 12.06% when using the 1000 ppm W-doped TiO2 films.

  1. 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.

  2. Cu doped TiO2/GF for photocatalytic disinfection of Escherichia coli in bioaerosols under visible light irradiation: Application and mechanism

    NASA Astrophysics Data System (ADS)

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2014-03-01

    This study investigated the role of Cu as a doping agent to enhance photocatalytic activity of TiO2 in Cu-doped TiO2/glass fibers (Cu-TiO2/GF) used for disinfection of Escherichia coli (E. coli) in aerosols under visible light irradiation. Glass fiber was used as a substrate to immobilize TiO2 for disinfection of E. coli in bioaerosols. Cu in the prepared photocatalyst acted as an intermediate agent for the transfer of photo-generated electrons from the valence band to the conduction band of TiO2. Cu dopants increased the electron-hole pair separation efficiency, inhibited their recombination leading to a lifetime increase of the generated electrons, and thus improved photocatalytic activity even under visible light irradiation. Cu also defected the TiO2 lattice by producing Ti3+ ions, which can increase the electron-hole separation capacity of the photocatalyst, thereby increasing photocatalytic capacity. The optimal Cu content in Cu/TiO2 to enhance the photocatalytic activity of TiO2 was 5 wt.%. Among three humidity conditions (dry (40 ± 5%), moderate (60 ± 5%) and humid (80 ± 5%)), the moderate condition showed the highest disinfection efficiency of E. coli. When the 5% Cu-TiO2/GF was used under a moderate level of humidity, the highest disinfection efficiency and disinfection capacity of E. coli were identified as 87.8% and 23 CFU/s cm2, respectively.

  3. Self-doped Ti3+-TiO2 as a photocatalyst for the reduction of CO2 into a hydrocarbon fuel under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Sasan, Koroush; Zuo, Fan; Wang, Yuan; Feng, Pingyun

    2015-08-01

    Self-doped TiO2 shows visible light photocatalytic activity, while commercial TiO2 (P25) is only UV responsive. The incorporation of Ti3+ into TiO2 structures narrows the band gap (2.90 eV), leading to significantly increased photocatalytic activity for the reduction of CO2 into a renewable hydrocarbon fuel (CH4) in the presence of water vapour under visible light irradiation.Self-doped TiO2 shows visible light photocatalytic activity, while commercial TiO2 (P25) is only UV responsive. The incorporation of Ti3+ into TiO2 structures narrows the band gap (2.90 eV), leading to significantly increased photocatalytic activity for the reduction of CO2 into a renewable hydrocarbon fuel (CH4) in the presence of water vapour under visible light irradiation. Electronic supplementary information (ESI) available: Experimental details, XPS, XRD and SEM images. See DOI: 10.1039/c5nr02974k

  4. 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

  5. Nitrogen and sulfur co-doped TiO2 nanosheets with exposed {001} facets: synthesis, characterization and visible-light photocatalytic activity.

    PubMed

    Xiang, Quanjun; Yu, Jiaguo; Jaroniec, Mietek

    2011-03-21

    Nitrogen and sulfur co-doped TiO(2) nanosheets with exposed {001} facets (N-S-TiO(2)) were prepared by a simple mixing-calcination method using the hydrothermally prepared TiO(2) nanosheets powder as a precursor and thiourea as a dopant. The resulting samples were characterized by transmission electron microscope, X-ray diffraction, N(2) adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The electronic properties of N,S co-doped TiO(2) were studied using the first-principle density functional theory (DFT). The photocatalytic activity of N-S-TiO(2) was evaluated by degradation of 4-chlorophenol (4-CP) aqueous solution under visible light irradiation. The production of hydroxyl radicals (˙OH) on the surface of visible-light-irradiated samples was detected by photoluminescence technique using terephthalic acid as a probe molecule. The results show that nitrogen and sulfur atoms were successfully incorporated into the lattice of TiO(2), which resulted in N-S-TiO(2) samples exhibiting stronger absorption in the UV-visible range with a red shift in the band gap transition. The first-principle DFT calculations further confirm that N and S co-dopants can induce the formation of new energy levels in the band gap, which is associated with the response of N-S-TiO(2) nanosheets to visible light irradiation. Surprisingly, pure TiO(2) nanosheets show the visible-light photocatalytic activity for the degradation of 4-CP mainly due to the substrate-surface complexation of TiO(2) and 4-CP, which results in extending absorption of titania to visible light region through ligand-to-titanium charge transfer. The N-S-TiO(2) samples studied exhibited an enhanced visible-light photocatalytic activity than pure TiO(2). Especially, the doped TiO(2) sample at the nominal weight ratio of thiourea to TiO(2) powder of 2 showed the highest photocatalytic activity, which was about twice greater than that of Degussa P25. The enhanced activity of

  6. 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

  7. 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.

  8. Lattice strain alteration and activation energy of phase transformation of TiO2 nanorods doped with silver and iron oxides

    NASA Astrophysics Data System (ADS)

    Riazian, M.

    2013-10-01

    TiO2 nanorods are synthesized by a thermal corrosion. In present work, synthesis of TiO2 nanorods in anatase, rutile and Ti8O15 phases, TiO2 nanorods embedded with silver and iron oxides as dopant by using the sol-gel method and alkaline corrosion are reported. The morphologies and crystal structures of TiO2 nanorods are characterized by use of field emission scanning electron microscopy, atomic force microscopy and X-ray diffractometer techniques. The obtained results illustrate an aggregative structure at high calcined temperatures with production of spherical particles. The effects of chemical compositions and calcined temperatures on surface topography and crystallization of phases are studied. Moreover, activation energy of nanoparticles formation in pure and doped state are calculated during thermal treatment.

  9. Effect of synergy on the visible light activity of B, N and Fe co-doped TiO2 for the degradation of MO.

    PubMed

    Xing, Mingyang; Wu, Yongmei; Zhang, Jinlong; Chen, Feng

    2010-07-01

    Single doped, co-doped and tri-doped TiO(2) with B, N and Fe are successfully synthesized by using the hydrothermal method. The samples are characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples are evaluated for degradation of methyl-orange (MO, 20 mg L(-1)) in aqueous solutions under visible light (lambda > 420 nm). The results of XRD suggest that all the catalysts present anatase crystal. All the doping catalysts show higher photoactivities than pure TiO(2) under visible light irradiation. In the single nonmetal doped TiO(2), the localized dopant levels near the valence band (VB) are responsible for the enhancement of photoactivies. Fe(3+) impurity level formed under the conduction band (CB) induces the high photocatalytic activities of iron doped TiO(2). In the co-doped and tri-doped catalysts, the B 2p and N 2p acceptor states contribute to the band gap narrowing by mixing with O 2p states combined with the overlapping of the conduction band by the iron "d" orbital, resulting in improvement of the photo-performance under visible light irradiation. Iron co-doped with boron catalyst shows low photoactivity under visible light due to the absence of Fe(3+) impurity levels at the bottom of the conduction band. In addition, the XPS results indicate the presence of synergistic effects in co-doped and tri-doped catalysts, which contribute to the enhancement of photocatalytic activities.

  10. Synergistic effects of graphene quantum dot sensitization and nitrogen doping of ordered mesoporous TiO2 thin films for water splitting photocatalysis(Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Islam, Syed Z.; Wanninayake, Namal; Reed, Allen D.; Kim, Doo-Young; Rankin, Stephen E.

    2016-10-01

    The optical and electronic properties of TiO2 thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO2, critical challenges include the innate inability of TiO2 to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, we prepared ordered mesoporous TiO2 films co-modified by graphene quantum dot sensitization and nitrogen doping (GQD-N-TiO2) for hydrogen production from photoelectrochemical water splitting under visible light irradiation. First, cubic ordered mesoporous TiO2 films were prepared by a surfactant templated sol-gel method. Then, TiO2 films were treated with N2/Ar plasma for the incorporation of substitutional N atoms into the lattice of TiO2. GQDs were prepared by chemically oxidizing carbon nano-onions. The immobilization of GQDs was accomplished by reacting carboxyl groups of GQDs with amine groups of N-TiO2 developed by the prior immobilization of (3-aminopropyl)triethoxysilane (APTES). Successful immobilization of GQDs onto N-TiO2 was probed by UV-Vis, FT-IR, and scanning electron microscopy. Further, zeta potential and contact angle measurements showed enhanced surface charge and hydrophilicity, confirming the successful immobilization of GQDs. The GQD-N-TiO2, N-TiO2 and GQD-TiO2 films showed 400 times, 130 times and 8 times photocurrent enhancement, respectively, compared to TiO2 films for water splitting with a halogen bulb light source. This outstanding enhancement is attributed to the high surface area of mesoporous films and synergistic effects of nitrogen doping and GQD sensitization resulting in enhanced visible light absorption, efficient charge separation and transport.

  11. 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.

  12. Photocatalytic degradation of glyphosate in water by N-doped SnO2/TiO2 thin-film-coated glass fibers.

    PubMed

    Kongsong, Peerawas; Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

    2014-01-01

    Photocatalytic degradation of glyphosate contaminated in water was investigated. The N-doped SnO2/TiO2 films were prepared via sol-gel method, and coated on glass fibers by dipping method. The effects of nitrogen doping on coating morphology, physical properties and glyphosate degradation rates were experimentally determined. Main variable was the concentration of nitrogen doping in range 0-40 mol%. Nitrogen doping results in shifting the absorption wavelengths and narrowing the band gap energy those lead to enhancement of photocatalytic performance. The near optimal 20N/SnO2/TiO2 composite thin film exhibited about two- and four-folds of glyphosate degradation rates compared to the undoped SnO2/TiO2 and TiO2 films when photocatalytic treatment were performed under UV and solar irradiations, respectively, due to its narrowest band gap energy (optical absorption wavelength shifting to visible light region) and smallest crystallite size influenced by N-doping.

  13. Modification of N-doped TiO2 photocatalysts using noble metals (Pt, Pd) - a combined XPS and DFT study.

    PubMed

    Batalović, K; Bundaleski, N; Radaković, J; Abazović, N; Mitrić, M; Silva, R A; Savić, M; Belošević-Čavor, J; Rakočević, Z; Rangel, C M

    2017-03-08

    Nitrogen-doped TiO2 (N-TiO2) is considered as one of the most promising materials for various photocatalytic applications, while noble metals Pd and Pt are known as good catalysts for hydrogen evolution. This work focuses on the determination of structural and electronic modifications of N-TiO2, achieved by noble metal deposition at the surface, as a starting indicator for potential applications. We focus on the properties of easily synthesized nanocrystalline nitrogen-doped anatase TiO2, modified by depositing small amounts of Pd (0.05 wt%) and Pt (0.10 wt%), aiming to demonstrate efficient enhancement of optical properties. The chemical states of dopants are studied in detail, using X-ray photoemission spectroscopy, to address the potential of N-TiO2 to act as a support for metallic nanoparticles. DFT calculations are used to resolve substitutional from interstitial nitrogen doping of anatase TiO2, as well as to study the combined effect of nitrogen doping and oxygen vacancy formation. Based on the binding energies calculated using Slater's transition state theory, dominant contribution to the N 1s binding energy at 399.8 eV is ascribed to interstitially doped nitrogen in anatase TiO2. Given that both structure and photocatalytic properties depend greatly on the synthesis procedure, this work contributes further to establishing correlation between the structure and optical properties of the noble metal modified N-TiO2 system.

  14. Enhanced photocatalytic degradation of humic acids using Al and Fe co-doped TiO2 nanotubes under UV/ozonation for drinking water purification.

    PubMed

    Yuan, Rongfang; Zhou, Beihai; Hua, Duo; Shi, Chunhong

    2013-11-15

    O3/UV/TiO2 was used to effectively decompose humic acids (HAs) in drinking water. To obtain a large specific surface area and low band gap energy, Al and Fe co-doped TiO2 nanotubes were successfully synthesized using the hydrothermal method. The effect of the optimal co-doped TiO2 nanotubes catalyst on the HAs removal efficiency through O3/UV/co-doped TiO2 process was investigated. The highest HAs removal efficiency (79.4%) that exhibited a pseudo-first-order rate constant of 0.172 min(-1) was achieved, in the presence of 550 °C calcined 1.0% co-doped TiO2 nanotubes with an Al:Fe ratio of 0.25:0.75. The effects of calcination temperature and doping concentration on anatase phase weight fractions, average crystallite sizes, Brunauer-Emmett-Teller surface area, catalyst band gap energy, and catalyst photocatalytic activity were also discussed. The inorganic anions also affected the catalyst photocatalytic ability. In a neutral solution, SO4(2-) slightly promoted HAs removal. However, HCO3(-) was found to significantly inhibit the catalyst activity, whereas Cl(-) had negligible effect on photocatalytic ability.

  15. [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.

  16. Removal of toluene from water by photocatalytic oxidation with activated carbon supported Fe(3+)-doped TiO2 nanotubes.

    PubMed

    Yuan, Rongfang; Zhou, Beihai; Ma, Li

    2014-01-01

    In this work, activated carbon (AC)-supported TiO2 containing 1.0% (mass percent) of 1.0 at.% (atomic percent) Fe(3+)-doped TiO2 nanotubes (Fe-TNTs) were successfully synthesized. The catalyst was used to effectively decompose toluene in water under O3/UV conditions, and some properties including the morphology, X-ray photoelectron spectroscopy, X-ray diffraction patterns, specific surface area and UV-visible diffuse reflectance spectroscopy were analyzed. A removal efficiency of 90.7% was achieved in the presence of fresh AC-supported Fe-TNTs calcined at 550 °C, with a pseudo-first-order rate constant of 0.038/min. The removal efficiency of toluene was reduced when the catalysts were repeatedly used, since the amount of adsorption sites of the supporting substrates decreased. However, even after AC-supported catalyst was used four times, the removal efficiency of toluene was still sufficient in water treatment. The enhanced photocatalytic activity of AC-supported Fe-TNTs was related to the synergistic effect of AC adsorption and Fe-TNTs photocatalytic ozonation. The water from a petrochemical company in China was used to obtain the removal efficiency of the pollutants, and the toluene and total organic carbon removal efficiencies were 69.9% and 58.3%, respectively.

  17. Preliminary Investigation of High-K Materials -Tio2 Doped Ta2o5 Films by Remote Plasma Ald

    NASA Astrophysics Data System (ADS)

    Fang, Q.; Hodson, C.; Liu, M.; Fang, Z. W.; Potter, R.; Gunn, R.

    (TiO2)x(Ta2O5)1-x (x is up to 0.45) films deposited by a remote plasma atomic layer deposition (ALD) are reported in this work. The growth rates of the ALD films measured by ellipsometer are in a range of 0.8 - 1.06 Å/cycle at a deposition temperature of 300°C, depending on Ti/(Ti+Ta) ratio. In order to evaluate the high-k materials of Ti-doped Ta2O5 films, EDX and AES were used for determining the composition of the films. The thickness and optical properties of the films were measured by a spectral ellipsometer and CV-measurement was applied for testing the electrical property of the film. Furthermore, the effects of thermal annealing and in-situ O2-oxidation on thickness, refractive index and electrical property of (TiO2)x(Ta2O5)1-x films are also discussed.

  18. TiO2 nanowire arrays modified with a simultaneous "etching, doping and deposition" technique for ultrasensitive amperometric immunosensing.

    PubMed

    Liu, Xiaoqiang; Huo, Xiaohe; Liu, Peipei; Tang, Yunfei; Xu, Jun; Ju, Huangxian

    2017-06-15

    In this work, an ultrasensitive immunosensing scaffold was structured with TiO2 nanowire (TiNW) arrays modified with molybdenum (Mo) and MoS2 flakes by a triplex "etching, doping and deposition" technique. The triply modification of TiNW arrays improved their electron transfer, and the decoration of MoS2 flakes on TiNW arrays increased both the conductivity and the specific surface area of TiNW. Accordingly, the triply modified TiNW arrays provided a biocompatible microenviroment for the biomolecules and high specific surface area to load big amount of biomolecules. The immunosensor was prepared by immobilizing capture antibody on the scaffold surface with double amino-reactive crosslinker, and the tracing labels were prepared by immobilizing signal antibody and horseradish peroxidase molecules on cylinder-shaped TiO2 nanorods. After sandwich-type immunoreaction, the tracing labels were quantitatively captured on the immunosensor surface for the detection of carcinoembryonic antigen as a model analyte. This amperometric method showed a linear range of 0.001 and 150ngmL(-1) with a detection limit of 0.5pgmL(-1). This work provided a promising platform for sensitive amperometric immunosensing of protein biomarkers.

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

    PubMed Central

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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.