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International Journal of Photoenergy
Volume 2012 (2012), Article ID 797968, 10 pages
http://dx.doi.org/10.1155/2012/797968
Research Article

One-Pot Template-Free Hydrothermal Synthesis of Monoclinic Hollow Microspheres and Their Enhanced Visible-Light Photocatalytic Activity

1State Key Laboratory of Silicate Materials for Architectures, Materials College, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China
2Department of Chemistry, School of Science, Wuhan University of Technology, Wuhan 430070, China

Received 24 October 2011; Accepted 4 November 2011

Academic Editor: Baibiao Huang

Copyright © 2012 Bei Cheng 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

Monoclinic-phase BiVO4 hollow microspheres with diameters of about 2–4 μm have been successfully fabricated in high yield by a one-pot template-free hydrothermal route. The reaction duration and urea concentration are shown to play important roles in the formation of the BiVO4 hollow microspheres. X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption isotherms, fourier transform infrared spectrometry, and UV-visible diffuse reflectance spectroscopy are used to characterize the products. The results show that all the as-prepared BiVO4 samples have monoclinic phase structure and exhibit good crystallinity. A formation mechanism for the BiVO4 hollow spherical structure via a localized Ostwald ripening is proposed based on the experimental observations. In addition, studies of the photocatalytic properties by exposure to visible light irradiation demonstrate that the as-obtained BiVO4 hollow spheres show potential photocatalytic application. Hydroxyl radicals (OH) are not detected on the surface of visible-light-illuminated BiVO4 by the photoluminescence technique, suggesting that OH is not the dominant photooxidant and photogenerated hole could directly take part in photocatalytic reaction. The prepared BiVO4 hollow spheres are also of great interest in pigment, catalysis, separation technology, biomedical engineering, and nanotechnology.