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International Journal of Photoenergy
Volume 2012, Article ID 823498, 6 pages
http://dx.doi.org/10.1155/2012/823498
Research Article

Effect of Fe Concentration on Fe-Doped Anatase TiO2 from GGA + U Calculations

1Department of Materials Engineering, Ming Chi University of Technology, 84 Gungjuan Road, Taishan, New Taipei 24301, Taiwan
2Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei 24301, Taiwan

Received 28 February 2012; Revised 23 May 2012; Accepted 29 May 2012

Academic Editor: Jincai Zhao

Copyright © 2012 Hsuan-Chung Wu 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

To comprehend the photocatalytic mechanisms of anatase T i 1 − 𝑥 F e 𝑥 O2 with various concentrations of Fe, this study performed first principles calculations based on density functional theory with Hubbard U on-site correction to evaluate the crystal structure, impurity formation energy, and electronic structure. We adopted the effective Hubbard U values of 8.47 eV for Ti 3d and 6.4 eV for Fe 3d. The calculations show that higher concentrations of Fe are easily formed in anatase TiO2 due to a reduction in the formation energy. The band gap of Fe-doped TiO2 decreases Fe doping level increases as a result of the overlap among the Fe 3d, Ti 3d, and O 2p states, which enhances photocatalytic activity in the visible light region. Additionally, a broadening of the valence band and Fe impurity states within the band gap might also contribute to the photocatalytic activity.