Structural characteristics of mixed oxides MOb>xb>/SiOb>2b> affecting photocatalytic decomposition of methylene blue

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• 作者：V.M. Gun&rsquo ; ko^a ; J.P. Blitz^b ; ^{jpblitz@eiu.edu} ; B. Bandaranayake^b ; E.M. Pakhlov^a ; V.I. Zarko^a ; I.Ya. Sulym^a ; K.S. Kulyk^a ; M.V. Galaburda^a ; V.M. Bogatyrev^a ; O.I. Oranska^a ; M.V. Borysenko^a ; R. Leboda^c ; J. Skubiszewska-Zi臋ba^c ; W. Janush^c
• 关键词：61.43.Gt (Powders porous materials) ; 68.08.-p (Liquid&ndash ; solid interfaces) ; 68.43.-h (Chemisorption/physisorption ; adsorbates on surfaces) ; 68.35.Md (Surface thermodynamics surface energies)
• 刊名：Applied Surface Science
• 出版年：2012
• 期刊代码：6_01694332
• 类别：ms
• 出版时间：15 June, 2012
• 卷：258
• 期：17
• 页码：6288-6296
• 文件大小：1577 K

摘要

A series of photocatalysts based on silica (nanoparticulate) supported titania, ceria, and ceria/zirconia were synthesized and characterized by a variety of techniques including surface area measurements, X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, surface charge density, and photocatalytic behavior toward methylene blue decomposition. Thermal treatment at 600 掳C increases the anatase content of the titania based catalysts detected by XRD. Changes in the infrared spectra before and after thermal treatment indicate that at low temperature there are more SiOTi bonds than at high temperature. As these bonds break upon heating the SiOb>2b> and TiOb>2b> separate, allowing the TiOb>2b> anatase phase to form. This results in an increased catalytic activity for the thermally treated samples. Nearly all titania based samples exhibit a negative surface charge density at pH 7 (initial pH of photocatalytic studies) which aids adsorption of methylene blue. The crystallinity of ceria and ceria/zirconia based catalysts are in some cases limited, and in others non-existent. Even though the energy band gap (Eb>gb>) can be lower for these catalysts than for the titania based catalysts, their photocatalytic properties are inferior.