Effect of oxygen vacancy in tungsten oxide on the photocatalytic activity for decomposition of organic materials in the gas phase

Abstract The relationship between the oxygen vacancy of tungsten oxide and its ability to decompose organic materials under visible-light irradiation was investigated experimentally. In the field of rechargeable batteries, the highest charge-discharge rate is obtained when tungsten oxide is used as a negative electrode with an O/W ratio of 2.72. This result suggested that the number of oxygen vacancies in tungsten oxide affects the photocatalytic decomposition behavior of organic materials. Therefore, with the aim of increasing the photocatalytic activity of tungsten oxide to decompose organic materials, we attempted to clarify the role of the oxygen vacancy. WO3 − x nanoparticles, including WO2.83 and WO2.72 nanoparticles, were fabricated by changing the annealing temperature in a 10% H2, 90% N2 atmosphere to generate different densities of oxygen vacancies. Tungsten oxide with O/W ratios of 2.83 and 2.72 exhibited no photocatalytic activity for the photodecomposition of organic materials. The maximum decomposition rate was obtained for stoichiometric WO3 (O/W = 3). The reason for the decrease or disappearance of the photodecomposition ability should originate in the increase in the number of electrons generated by the oxygen vacancies. These excess electrons promote the recombination reaction between electrons and holes in WO3 − x, and hence reduce the lifetime of electron-hole pairs.

[1]  Tao Wu,et al.  Self-doped Ti3+ enhanced photocatalyst for hydrogen production under visible light. , 2010, Journal of the American Chemical Society.

[2]  C. E. Tracy,et al.  Raman spectroscopic studies of electrochromic a-WO3 , 1999 .

[3]  V. Wittwer,et al.  Dependence of WO 3 Electrochromic Absorption on Crystallinity , 1977 .

[4]  R. Hall Electron-Hole Recombination in Germanium , 1952 .

[5]  K. Hashimoto,et al.  Efficient visible light-sensitive photocatalysts: Grafting Cu(II) ions onto TiO2 and WO3 photocatalysts , 2008 .

[6]  K. Asai,et al.  Preparation of S-doped TiO2 photocatalysts and their photocatalytic activities under visible light , 2004 .

[7]  Wei Li,et al.  Electron transport mechanism of tungsten trioxide powder thin film studied by investigating effect of annealing on resistivity , 2015, Microelectron. Reliab..

[8]  M. Miyauchi Photocatalysis and photoinduced hydrophilicity of WO3 thin films with underlying Pt nanoparticles. , 2008, Physical chemistry chemical physics : PCCP.

[9]  A. Szabó,et al.  Stability and Controlled Composition of Hexagonal WO3 , 2008 .

[10]  Wei Li,et al.  Improvement of charge/discharge performance for lithium ion batteries with tungsten trioxide electrodes , 2015, Microelectron. Reliab..

[11]  Yichuan Ling,et al.  Hydrogen-treated TiO2 nanowire arrays for photoelectrochemical water splitting. , 2011, Nano letters.

[12]  Xiaobo Chen,et al.  Increasing Solar Absorption for Photocatalysis with Black Hydrogenated Titanium Dioxide Nanocrystals , 2011, Science.

[13]  N. Grobert,et al.  Generation of hollow crystalline tungsten oxide fibres , 2000 .

[14]  B. Ohtani,et al.  Pristine simple oxides as visible light driven photocatalysts: highly efficient decomposition of organic compounds over platinum-loaded tungsten oxide. , 2008, Journal of the American Chemical Society.

[15]  W. Read,et al.  Statistics of the Recombinations of Holes and Electrons , 1952 .

[16]  T. Yokoyama,et al.  Visible Light-Sensitive Cu(II)-Grafted TiO2 Photocatalysts: Activities and X-ray Absorption Fine Structure Analyses , 2009 .

[17]  Nobuto Oka,et al.  Visible-light active photocatalytic WO3 films loaded with Pt nanoparticles deposited by sputtering. , 2012, Journal of nanoscience and nanotechnology.

[18]  T. Leichtweiss,et al.  Correlation of electrochromic properties and oxidation states in nanocrystalline tungsten trioxide. , 2015, Physical Chemistry, Chemical Physics - PCCP.

[19]  M. Sunkara,et al.  WO3 and W2N nanowire arrays for photoelectrochemical hydrogen production , 2009 .

[20]  G. Gary Wang,et al.  Hydrogen-treated WO3 nanoflakes show enhanced photostability , 2012 .

[21]  Nobuto Oka,et al.  Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering , 2015 .

[22]  Nobuto Oka,et al.  Visible light-induced photocatalytic properties of WO3 films deposited by dc reactive magnetron sputtering , 2012 .

[23]  P. Fornasiero,et al.  Nonaqueous synthesis of TiO2 nanocrystals using TiF4 to engineer morphology, oxygen vacancy concentration, and photocatalytic activity. , 2012, Journal of the American Chemical Society.

[24]  Masaaki Kitano,et al.  Recent developments in titanium oxide-based photocatalysts , 2007 .

[25]  Liejin Guo,et al.  Nanostructured WO₃/BiVO₄ heterojunction films for efficient photoelectrochemical water splitting. , 2011, Nano letters.

[26]  R. Asahi,et al.  Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides , 2001, Science.

[27]  H. Arakawa,et al.  The effect of selected reaction parameters on the photoproduction of oxygen and hydrogen from a WO3-Fe2+-Fe3+ aqueous suspension , 1999 .