Origin of visible-light-driven photocatalysis: A comparative study on N/F-doped and N–F-codoped TiO2 powders by means of experimental characterizations and theoretical calculations

An overall comparative study was carried out on N-doped, F-doped, and N-F-codoped TiO{sub 2} powders (NTO, FTO, NFTO) synthesized by spray pyrolysis in order to elucidate the origin of their visible-light-driven photocatalysis. The comparisons in their experimentally obtained characteristics were based on the analysis of XPS, UV-Vis, PL, NH{sub 3}-TPD and ESR spectra. The comparisons in their theoretically predicted properties were based on the analysis of the calculated electronic structures. As the results, N-doping into TiO{sub 2} resulted in not only the improvement in visible-light absorption but also the creation of surface oxygen vacancies. F-doping produced several beneficial effects including the creation of surface oxygen vacancies, the enhancement of surface acidity and the increase of Ti{sup 3+} ions. Doped N atoms formed a localized energy state above the valence band of TiO{sub 2}, whereas doped F atoms themselves had no influence on the band structure. The photocatalytic tests indicated that the NFTO demonstrated the highest visible-light activity for decompositions of both acetaldehyde and trichloroethylene. This high activity was ascribed to a synergetic consequence of several beneficial effects induced by the N-F-codoping.

[1]  M. Payne,et al.  Electronic structure, properties, and phase stability of inorganic crystals: A pseudopotential plane‐wave study , 2000 .

[2]  C. Peden,et al.  Interaction of Molecular Oxygen with the Vacuum-Annealed TiO2(110) Surface: Molecular and Dissociative Channels , 1999 .

[3]  F. Saito,et al.  Preparation of nitrogen-doped titania with high visible light induced photocatalytic activity by mechanochemical reaction of titania and hexamethylenetetramine , 2003 .

[4]  W. Stickle,et al.  Handbook of X-Ray Photoelectron Spectroscopy , 1992 .

[5]  W. Ingler,et al.  Efficient Photochemical Water Splitting by a Chemically Modified n-TiO2 , 2002, Science.

[6]  Yuka Watanabe,et al.  Nitrogen-Concentration Dependence on Photocatalytic Activity of TiO2-xNx Powders , 2003 .

[7]  Jackson,et al.  Atoms, molecules, solids, and surfaces: Applications of the generalized gradient approximation for exchange and correlation. , 1992, Physical review. B, Condensed matter.

[8]  H. Idriss,et al.  Structure sensitivity and photocatalytic reactions of semiconductors. Effect of the last layer atomic arrangement. , 2002, Journal of the American Chemical Society.

[9]  Hajime Haneda,et al.  Fluorine-doped TiO2 powders prepared by spray pyrolysis and their improved photocatalytic activity for decomposition of gas-phase acetaldehyde , 2005 .

[10]  S. Yamamoto,et al.  Fluorine-doping in titanium dioxide by ion implantation technique , 2003 .

[11]  S. Matsuzawa,et al.  Preparation of a visible light-responsive photocatalyst from a complex of Ti4+ with a nitrogen-containing ligand , 2004 .

[12]  William H. Press,et al.  Numerical recipes , 1990 .

[13]  Jiaguo Yu,et al.  Effects of F- Doping on the Photocatalytic Activity and Microstructures of Nanocrystalline TiO2 Powders , 2002 .

[14]  A. Emeline,et al.  Spectral Dependencies of the Quantum Yield of Photochemical Processes on the Surface of Wide Band Gap Solids. 3. Gas/Solid Systems† , 2000 .

[15]  J. Yates,et al.  Photocatalysis on TiO2 Surfaces: Principles, Mechanisms, and Selected Results , 1995 .

[16]  Lee,et al.  Implementation of ultrasoft pseudopotentials in ab initio molecular dynamics. , 1991, Physical review. B, Condensed matter.

[17]  N. Ohashi,et al.  Visible-Light-Driven N−F−Codoped TiO2 Photocatalysts. 2. Optical Characterization, Photocatalysis, and Potential Application to Air Purification , 2005 .

[18]  J. Nørskov,et al.  Oxygen vacancies as active sites for water dissociation on rutile TiO(2)(110). , 2001, Physical review letters.

[19]  M. Komiyama,et al.  Photoresponse of Titanium Dioxide Surface on Atomic Scale: Site for Visible Light Absorption , 2004 .

[20]  Akira Fujishima,et al.  Titanium dioxide photocatalysis , 2000 .

[21]  R. Grimes,et al.  Theoretical study of perfect and defective TiO2 crystals , 1996 .

[22]  N. Ohashi,et al.  Visible-light-driven nitrogen-doped TiO2 photocatalysts: effect of nitrogen precursors on their photocatalysis for decomposition of gas-phase organic pollutants , 2005 .

[23]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

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

[25]  James L. Gole,et al.  Highly Efficient Formation of Visible Light Tunable TiO2-xNx Photocatalysts and Their Transformation at the Nanoscale , 2004 .

[26]  M. Grätzel,et al.  EPR observation of trapped electrons in colloidal titanium dioxide , 1985 .

[27]  N. Serpone,et al.  Size Effects on the Photophysical Properties of Colloidal Anatase TiO2 Particles: Size Quantization versus Direct Transitions in This Indirect Semiconductor? , 1995 .

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

[29]  S. Ogale,et al.  Synthesis of Nanophase TiO2 by Ion Beam Sputtering and Cold Condensation Technique , 1998 .

[30]  A. Emeline,et al.  Photostimulated Generation of Defects and Surface Reactions on a Series of Wide Band Gap Metal-Oxide Solids , 1999 .

[31]  A. Volodin.  Photoinduced phenomena on the surface of wide-band-gap oxide catalysts , 2000 .

[32]  T Ihara,et al.  Visible-light-active titanium oxide photocatalyst realized by an oxygen-deficient structure and by nitrogen doping , 2003 .

[33]  J. Védrine,et al.  Electron paramagnetic resonance investigation of oxygen photoadsorption and its reactivity with carbon monoxide on titanium dioxide: the O3–3 species , 1976 .

[34]  S. Rodrigues,et al.  Structural defects cause TiO2-based photocatalysts to be active in visible light. , 2004, Chemical communications.

[35]  Yong Lei,et al.  Preparation and photoluminescence of highly ordered TiO2 nanowire arrays , 2001 .

[36]  Hajime Haneda,et al.  Visible-Light-Driven N−F−Codoped TiO2 Photocatalysts. 1. Synthesis by Spray Pyrolysis and Surface Characterization , 2005 .

[37]  S. Morrison.  Surface states associated with acid sites on solids , 1975 .

[38]  H. Tada,et al.  Photoreactivity of Sol−Gel TiO2 Films Formed on Soda-Lime Glass Substrates: Effect of SiO2 Underlayer Containing Fluorine , 1999 .

[39]  M. Grätzel,et al.  EPR study of hydrated anatase under UV irradiation , 1987 .

[40]  Harland G. Tompkins,et al.  Titanium nitride oxidation chemistry: An x‐ray photoelectron spectroscopy study , 1992 .

[41]  S. Martin,et al.  Environmental Applications of Semiconductor Photocatalysis , 1995 .

[42]  V. Keller,et al.  Photocatalytic oxidation of butyl acetate in vapor phase on TiO2, Pt/TiO2 and WO3/TiO2 catalysts , 2003 .

[43]  Iis Sopyan,et al.  An efficient TiO2 thin-film photocatalyst: photocatalytic properties in gas-phase acetaldehyde degradation , 1996 .