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International Journal of Photoenergy
Volume 2012, Article ID 759306, 9 pages
http://dx.doi.org/10.1155/2012/759306
Research Article

Mechanistic Study of Visible-Light-Induced Photodegradation of 4-Chlorophenol by TiO2−xNx with Low Nitrogen Concentration

1Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
2State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, China
3Department of Chemistry, Tsinghua University, Beijing 100084, China

Received 7 April 2011; Accepted 3 May 2011

Academic Editor: Jiaguo Yu

Copyright © 2012 Guangfeng Shang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

TiO2−x Nx powders with low N-doping concentrations ( 0 . 0 2 1 < 𝑥 < 0 . 0 4 9 ) were prepared by annealing commercial TiO2 (P-25) under an NH3 flow at 550°C. Regardless of UV or visible case, the photoactivities of the samples decreased as x increased, and TiO1.979N0.021 showed the highest activity for the 4-chlorophenol (4-CP) decomposition under the visible-light irradiation. The visible-light response for N-doped TiO2 could arise from an N-induced midgap level, formed above the valence band (O 2p). Electron spin resonance (ESR) measurements and the radical scavenger technologies gave the combined evidence that the active species ( O H and O 2 ) are responsible for the photodecomposition of 4-CP over TiO2−xNx under the visible irradiation. A possible photocatalytic mechanism was discussed in detail.