Electrocatalytic Hydrogen Evolution and Oxygen Reduction on Polyoxotungstates/Graphene Nanocomposite Multilayers

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• 作者：Min Jiang ; Dandan Zhu ; Jinjun Cai ; Hongyu Zhang ; Xuebo Zhao
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 3, 2014
• 年：2014
• 卷：118
• 期：26
• 页码：14371-14378
• 全文大小：437K
• ISSN：1932-7455

文摘

Negatively charged Pressler-type heteropolytungstate K_12.5Na_1.5[NaP₅W₃₀O₁₁₀] (P₅W₃₀) clusters and graphene oxide (GO) were constructed into polyoxotungstates/graphene (POTs/G) nanocomposite multilayer with protonated poly(ethylenimine) (PEI) via layer-by-layer self-assembly. The growth process of (PEI/P₅W₃₀鈥揋O)_n multilayer films was monitored by UV鈥搗isible spectroscopy and cyclic voltammetry. The atomic force microscopy images clearly showed the morphology of single-sheet GO in multilayer films. The UV-light irradiation of multilayers afforded reduced graphene oxide (RGO) in the multilayers. The changes in composition of C 1s in GO, W 4f in P₅W₃₀, and N 1s in PEI were detected by X-ray photoelectron spectroscopy. A possible photoreduction mechanism of GO was proposed. The electrochemical behavior of (PEI/P₅W₃₀鈥揜GO)_n multilayers modified on a glassy carbon electrode at room temperature and their electrocatalytic activity toward oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) were investigated. At a potential of 鈭?.6 V, the multilayers clearly exhibited electrocatalytic activity for ORR via almost a four-electron reduction pathway to H₂O. A remarkable electrocatalytic HER could be detected on the (PEI/P₅W₃₀鈥揜GO)_n multilayer, whereas the (PEI/P₅W₃₀鈥揋O)_n multilayer did not show any HER signal in the same potential range. This study investigated and extended the application of POTs/G nanocomposites to the electrocatalysis of ORR and HER.