Thermostability and photocatalytic performance of BiOCl 0.5 Br 0.5 composite microspheres
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Jiade Li School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi, People’s Republic of China; and State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350002, Fujian, People’s Republic of China
Wanqin Zhou and Lihua Zhu School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi, People’s Republic of China (Received 26 June 2015; accepted 9 September 2015)
Novel 1–1.5 lm BiOCl0.5Br0.5 composite microspheres were prepared by coprecipitation method, then calcined at different temperatures. The BiOCl0.5Br0.5 samples before and after calcination were characterized by powder x-ray diffraction, thermogravimetric analysis, N2-physical adsorption, scanning electron microscopy, Fourier transformed infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. The results showed that the thermostability of BiOCl0.5Br0.5 composite microspheres is lower than BiOCl and higher than BiOBr. Heat treatment at low 500 °C could obviously improve the crystallinity of BiOCl0.5Br0.5 microspheres, resulting in a significant increase in activity. BiOCl0.5Br0.5 microspheres calcined at 450 °C displayed the highest activity and stability. At elevated temperature calcination (600–800 °C), phase transition occurred over BiOCl0.5Br0.5. Br element was gradually lost and new phase of Bi24O31Br10 appeared. High temperature calcination did not change the morphology of BiOCl0.5Br0.5, but the surface area and surface OH groups decreased, which resulted in a large decrease in activity. I. INTRODUCTION
Environmental pollution is a global problem, which has attracted great attention of human being. Semiconductor photocatalysis is one of the environmentally friendly processing technologies rising in recent years.1–4 It was given intensive attention in environmental improvement, especially in degradation, mineralization of organic pollutants in water owing to its simple equipments, mild reaction conditions, low energy consumption, and less secondary pollution.5–8 High efficient photocatalysts is the core of photocatalysis technology. BiOX (X 5 Cl, Br, I) compounds, a class of semiconductors, have highly anisotropic layered structure that contributes to the fast separation of photo-generated electrons and holes and charge transfer. Also, its ability of light absorption could be controlled and adjusted elaborately through the species and content of the halogens in compound, and light
Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.299 J. Mater. Res., Vol. 30, No. 20, Oct 28, 2015
absorption can be extended from ultraviolet to visible light region. Therefore, BiOX semiconductors always display obviously photocatalytic activity in degradation of organic pollutants to CO2 and H2O.9–12 Th
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