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Visible-Light-Driven Photodegradation of Contaminants in Water over Surface-Engineered BiOBr Semiconductor Micro/Nano-Structures
Zheng Jiang1,2, Liang Kong1, Tiancun Xiao1, Peter P. Edwards1
(1)Jesus College, University of Oxford, Oxford, OX1 3DW, U.K.; (2)Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, U.K.
Visible-Light-Driven Photocatalytic degradation of contaminants (PDC) over semiconductor photocatalysts represents an advanced, cost-efficient and promising water purification technology because it can utilize the large portion of energy in the free sun light1,2. However, the implementation of PDC technique is is still facing a great challenge over the effective and stable visible-light-responsive photocatalysts with desired structure and surface functionality. Extensive efforts have been made to enhance the adsorption of sunlight and depress the recombination of the photogenerated charges for maximum photocatalytic efficiency. Semiconductor BiOBr is an attractive photocatalyst with excellent Uv-Vis light illumination despite its adsorption of sunlight is limited by its relatively large bandgap3,4. This talk will focus on the strategies we developed to resolve the crucial issues over the BiOBr semiconductor by semiconductor surface-engineering. An efficient and controllable synthesis methodology has been developed to prepare BiOBr mico-/nano-structures with desired visible-light adsorption.
First, a rapid synthesis route was developed to prepare BiOBr nanoflowers with exposed highly reactive surfaces and it was further adopted to prepare heterojucntions composed of BiOBr and second semiconductors. The results reveal the surface-oriented BiOBr and its heterojunctions possess hierarchical architectures and ultrahigh activity under visible-light irradiation in photodegradation of several typical refractory model organic pollutants. The synergism effects of the enhanced surface absorption, enhanced light adsorption, mitigated light-scattering, and special hierarchical structures were unearthed through key characterizations. Second, visible-light-induced photodeposition was adopted to prepare the surface supported noble-metal/BiOBr photocatalysts and the effects of the NM on the BiOBr surface were explored. It was found that the surface NMs deteriorated the photocatalytic performance of the BiOBr photocatalysts, although the surface NMs significantly improve the stability of the BiOBr under long-term light exposure. The mechanism was proposed on basis of the surface engineering, and band structure of the multi-structures.
The correlation of the photocatalytic activity to its structure and surface will be discussed on basis of the detailed physicochemical characterization and theoretical analyses.
References:
1. Z Jiang, T Xiao,V Kuznetzov, P.P. Edwards, Phil. Trans. R. Soc. A; 2010, 368; 3343-3364;
2. Z. Jiang, F. Yangb, N. Luo, B. T. T. Chu, D. Sun, H. Shia, T. Xiao, P. P. Edwards, Chem. Commun., 2008, 6372-6374
3. L. Kong, Z. Jiang, T. Xiao, L. Lu, M. O. Jones and P. P. Edwards, Chem. Commun., 2011, 47, 5512-5514
4. Z. Jiang, F. Yang, G. Yang, L. Kong, M. O. Jones, T. Xiao, P. P. Edwards, J PHOTOCHEM PHOTOBIOL A-CHEM , 2010,212(1): 8-13.