Mediator Enhanced Water Oxidation Using Rb4[RuII(bpy)3]5[{RuIII4O4(OH)2(H2O)4}(纬-SiW1

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• 作者：Si-Xuan Guo ; Chong-Yong Lee ; Jie Zhang ; Alan M. Bond ; Yurii V. Geletii ; Craig L. Hill
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：July 21, 2014
• 年：2014
• 卷：53
• 期：14
• 页码：7561-7570
• 全文大小：468K
• ISSN：1520-510X

文摘

The water insoluble complex Rb₄[Ru^II(bpy)₃]₅[{Ru^III₄O₄(OH)₂(H₂O)₄}(纬-SiW₁₀O₃₆)₂], ([Ru^IIbpy]₅[Ru^III₄POM]), was synthesized from Rb₈K₂[{Ru^IV₄O₄(OH)₂(H₂O)₄}(纬-SiW₁₀O₃₆)₂] and used for electrocatalytic water oxidation under both thin- and thick-film electrode conditions. Results demonstrate that the [Ru^IIbpy]₅[Ru^III₄POM] modified electrode enables efficient water oxidation to be achieved at neutral pH using thin-film conditions, with [Ru(bpy)₃]³⁺([Ru^IIIbpy]) acting as the electron transfer mediator and [Ru^V₄POM] as the species releasing O₂. The rotating ring disc electrode (RRDE) method was used to quantitatively determine the turnover frequency (TOF) of the catalyst, and a value of 0.35 s^鈥? was obtained at a low overpotential of 0.49 V (1.10 V vs Ag/AgCl) at pH 7.0. The postulated mechanism for the mediator enhanced catalytic water process in a pH 7 buffer containing 0.1 M LiClO₄ as an additional electrolyte includes the following reactions (ion transfer for maintaining charge neutrality is omitted for simplicity): [Ru^IIbpy]₅[Ru^III₄POM] 鈫?[Ru^IIIbpy]₅[Ru^V₄POM] + 13 e^{鈥?/sup> and [RuIIIbpy]₅[RuV₄POM] + 2H₂O 鈫?[RuIIIbpy]₅[RuIV₄POM] + O₂ + 4H+. The voltammetry of related water insoluble [RuIIbpy]₂[S₂M₁₈O₆₂] (M = W and Mo) and [FeIIPhen]_x[RuIII₄POM] materials has also been studied, and the lack of electrocatalytic water oxidation in these cases supports the hypothesis that [RuIIIbpy] is the electron transfer mediator and [RuV₄POM] is the species responsible for oxygen evolution.}