Electron Transfer Mediator Effects in Water Oxidation Catalysis by Solution and Surface-Bound Ruthenium Bpy-Dicarboxylate Complexes

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• 作者：Matthew V. Sheridan ; Benjamin D. Sherman ; Seth L. Marquard ; Zhen Fang ; Dennis L. Ashford ; Kyung-Ryang Wee ; Alexander S. Gold ; Leila Alibabaei ; Jennifer A. Rudd ; Michael K. Coggins ; Thomas J. Meyer
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：November 12, 2015
• 年：2015
• 卷：119
• 期：45
• 页码：25420-25428
• 全文大小：538K
• ISSN：1932-7455

文摘

Electrocatalytic water oxidation by the catalyst, ruthenium 2,2鈥?bipyridine-6,6鈥?dicarboxylate (bda) bis-isoquinoline (isoq), [Ru(bda)(isoq)₂], 1, was investigated at metal oxide electrodes surface-derivatized with electron transfer (ET) mediators. At indium-doped tin oxide (ITO) in pH 7.2 in H₂PO₄^{鈥?/sup>/HPO₄2鈥?/sup> buffers in 0.5 M NaClO₄ with added acetonitrile (MeCN), the catalytic activity of 1 is enhanced by the surface-bound redox mediators [Ru (4,4鈥?PO₃H₂-bpy)(4,4鈥?R-bpy)₂]2+ (RuPbpyR₂2+, R = Br, H, Me, or OMe, bpy = 2,2鈥?bipyridine). Rate-limiting ET between the Ru3+ form of the mediator and the RuIV(O) form in the [RuV/IV(O)]+/0 couple of 1 is observed at relatively high concentrations of HPO₄2鈥?/sup> buffer base under conditions where O路路路O bond formation is facilitated by atom-proton transfer (APT). For the solution [Ru(bpy)₃]3+/2+ mediator couple and 1 as the catalyst, catalytic currents vary systematically with the concentration of mediator and the HPO₄2鈥?/sup> buffer base concentration. Electron transfer mediation of water oxidation catalysis was also investigated on nanoparticle TiO₂ electrodes co-loaded with catalyst [Ru(bda)(py-4-O(CH₂)₃-PO₃H₂)₂], 2, (py = pyridine) and RuPbpyR₂2+ (R = H, Me, or OMe) with an interplay between rate-limiting catalyst oxidation and rate-limiting O路路路O bond formation by APT. Lastly, the co-loaded assembly RuPbpyR₂2+ + 2 has been investigated in a dye-sensitized photoelectrosynthesis cell for water splitting.}