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 H2PO4p>鈥?/sup>/HPO4p>2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]p>2+p> (RuPbpyR2p>2+p>, R = Br, H, Me, or OMe, bpy = 2,2鈥?bipyridine). Rate-limiting ET between the Rup>3+p> form of the mediator and the Rup>IVp>(O) form in the [Rup>V/IVp>(O)]p>+/0p> couple of 1 is observed at relatively high concentrations of HPO4p>2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]p>3+/2+p> mediator couple and 1 as the catalyst, catalytic currents vary systematically with the concentration of mediator and the HPO4p>2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 RuPbpyR2p>2+p> (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 RuPbpyR2p>2+p> + 2 has been investigated in a dye-sensitized photoelectrosynthesis cell for water splitting.