title: Effect of calcination temperatures on microstructures and photocatalytic activity of tungsten trioxide hollow microspheres.
abstract: Tungsten trioxide hollow microspheres were prepared by immersing SrWO4 microspheres in a concentrated HNO3 solution, and then calcined at different temperatures. The prepared tungsten oxide samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, differential thermal analysis-thermogravimetry, UV-visible spectrophotometry, scanning electron microscopy, N2 adsorption/desorption measurements. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that with increasing calcination temperatures, the average crystallite size and average pore size increased, on the contrary, Brunauer-Emmett-Teller-specific surface areas decreased. However, pore volume and porosity increased firstly, and then decreased. Increasing calcination temperatures resulted in the changes of surface morphology of hollow microspheres. The un-calcined and 300 degrees C-calcined samples showed higher photocatalytic activity than other samples. At 400 degrees C, the photocatalytic activity decreased greatly due to the decrease of specific surface areas. At 500 degrees C, the photocatalytic activity of the samples increased again due to the junction effect of two phases.
authors.affiliation: State Key Laboratory of Advanced Technology for Material Synthesis and processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070, PR China. jiaguoyu@yahoo.com
authors.forename: Jiaguo
authors.initials: J
authors.lastname: Yu
authors.forename: Lifang
authors.initials: L
authors.lastname: Qi
authors.forename: Bei
authors.initials: B
authors.lastname: Cheng
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Zhao
mesh_terms: D002384:Catalysis; D003460:Crystallization; D004055:Differential Thermal Analysis; D008669:Metallurgy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009584:Nitrogen / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D010777:Photochemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D016062:Porosity; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D014414:Tungsten / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides; D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; C511604:tungsten oxide; D009584:Nitrogen; D014414:Tungsten