Chemically Modified Electrode with a Film of Nano Ruthenium Oxides Stabilizing High Valent RuO4− Species and Its Redox-Selective Sequential Transformation to Polynuclear Ru

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• 作者：Annamalai Senthil Kumar ; Tomoaki Tanase ; Jyh-Myng Zen
• 刊名：Langmuir
• 出版年：2009
• 出版时间：December 1, 2009
• 年：2009
• 卷：25
• 期：23
• 页码：13633-13640
• 全文大小：1002K
• 年卷期：v.25,no.23(December 1, 2009)
• ISSN：1520-5827

文摘

High-valent Ru^VIIO₄⁻ (perruthenate) is a short-lived species in aqueous solutions (pH 1−14) and has scarcely been studied through electrochemistry. By a potential-controlled oxidative deposition method at 1 V vs Ag/AgCl using RuCl₃ in a pH 2 KCl-HCl buffer solution, chemically modified glassy carbon (GCE) and indium tin oxide (ITO) electrodes were successfully prepared with a film of hydrous nano ruthenium oxides RuO₂ and RuO₃, stabilizing the high-valent perruthenate anion (Ru(VII)-RuO_x-CME, x = 2 and 3, CME = chemically modified electrode). The electrodes showed three distinct redox peaks corresponding to Ru₂O₃/RuO₂, RuO₂/RuO₃, and RuO₄²⁻/RuO₄⁻ redox processes at pH 2, like the classical RuO₂ electrodes in alkaline conditions. Solid state UV−visible spectra of the ITO/Ru(VII)-RuO_x-CME showed characteristic absorption very close to chemically generated authentic RuO₄⁻ species in alkaline solution. Further, redox-controlled sequential procedures yielded polynuclear ruthenium oxide-hexacyanometallate films (RuO-MCN-CME, M = Fe and Ru), in which Ru(VII)-RuO_x-CME acted as a specific template. A controlled-potential activation (>1 V) of Ru(VII)-RuO_x-CME, stabilizing the key RuO₄⁻ species, in a solution of [Fe(CN)₆]³⁻ or [Ru(CN)₆]⁴⁻, should be a critical step for the formation of polynuclear RuO-MCN matrix.