Ruthenium Metallopolymer: Dawson Polyoxomolybdate 伪-[Mo18O54(SO4)2]4鈥?/sup> Adduct Films: Sensitization for Visible Photoelectrocatalysis

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• 作者：Jie Zhu ; James J. Walsh ; Alan M. Bond ; Tia E. Keyes ; Robert J. Forster
• 刊名：Langmuir
• 出版年：2012
• 出版时间：September 18, 2012
• 年：2012
• 卷：28
• 期：37
• 页码：13536-13541
• 全文大小：281K
• 年卷期：v.28,no.37(September 18, 2012)
• ISSN：1520-5827

文摘

Thin films of the adduct formed from the electrostatic association of the metallopolymer, [Ru(bpy)₂(PVP)₁₀]²⁺, and the Dawson polyoxomolybdate 伪-[Mo₁₈O₅₄(SO₄)₂]^{4鈥?/sup>, POMo, have been formed on ITO electrodes using an alternate immersion approach. The Ru/POMo ratio is 4.5:1, which exceeds the 2:1 ratio expected on the basis of the charges of the Ru2+ and POMo4鈥?/sup> building blocks. This behavior arises because of the polymeric character of the cation. In the presence of a substrate that has an abstractable proton such as benzyl alcohol, these ruthenium-sensitized polyoxomolybdate films generate significant photocurrents under visible irradiation. Significantly, increasing the surface coverage of the adduct from 1.4 脳 10鈥?0 to 8.1 脳 10鈥?0 mol cm鈥? does not measurably increase the photocurrent observed. Scan-rate-dependent cyclic voltammetry reveals that the rate of homogeneous charge transport through the film is slow, which most likely results in only a fraction of the film thickness being active for photoelectrocatalysis. The photocurrent increases markedly when the driving force for the oxidation of POMo5鈥?/sup>, created by the photoelectrocatalytic oxidation of benzyl alcohol, is increased. This result is consistent with the dynamics of heterogeneous electron transfer being centrally important to the regeneration of the photoelectrocatalyst. A system in which the surface coverage and applied overpotential are optimized produces a photocurrent density of 190 卤 18 nA cm鈥? under 480 卤 5 nm irradiation.}