Iodide ion photooxidation on the hetero-system WS2/TiO2 prepared by sol–gel

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• 作者：S. Boumaza ; B. Bellal ; M. Trari
• 刊名：Reaction Kinetics, Mechanisms and Catalysis
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：118
• 期：2
• 页码：439-450
• 全文大小：753 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Catalysis
  Industrial Chemistry and Chemical Engineering
  Physical Chemistry
  
• 出版者：Akad茅miai Kiad贸, co-published with Springer Science+Business Media B.V., Formerly Kluwer Academic
• ISSN：1878-5204
• 卷排序：118

文摘

The photoelectrochemical characterization of the hetero-system x % WS₂/TiO₂ (x = 0, 10 and 20) is undertaken to assess its photoactivity for iodide ion oxidation. The nanosized catalyst is prepared by sol–gel at 450 °C; the X-ray diffraction shows broad peaks with a specific surface area of 110 m2 g−1. The gap of WS₂ (1.72 eV), determined from the diffuse reflectance spectrum, is well matched to the solar spectrum. The flat band potential (−0.83 V_SCE) is more anodic than the I₂/I− level (~0.3 V_SCE), thus leading to iodide photooxidation. The electrochemical impedance spectroscopy reveals both the charge transfer and Warburg diffusion. The oxidation is catalyzed by dissolved oxygen through the formation of H₂O₂ and is optimized with respect to the I− concentration (0.25 M) and catalyst dose (1 mg L−1). A conversion rate of 81 % is reported under solar light within 3 h illumination. Hence, the heterosystem is attractive for the chemical storage through the reaction: (\(2 {\text{ I}}^{ - } + {\text{O}}_{ 2} + 2 {\text{ H}}_{ 2} {\text{O}} \to {\text{I}}_{ 2} + {\text{H}}_{ 2} {\text{O}}_{ 2} + 2 {\text{ OH}}^{ - } ,\Delta {\text{G}}_{\text{R}}^{^\circ } = 3 5. 3 2 \;{\text{kcal}} \;{\text{mol}}^{ - 1}\)).KeywordsHetero-system WS₂/TiO₂Iodide oxidationPhotoelectrochemicalSolar light