Water oxidation is a vital anodic reaction for renewable fuel generation via electrochemical- and photoelectrochemical-driven water splitting or CO2 reduction. Ruthenium complexes, such as Ru-bda family, have been shown as highly efficient water-oxidation catalysts (WOCs), particularly when they undergo a bimolecular O-O bond formation pathway. In this study, a novel Ru(pda)-type (pda2- =1,10-phenanthroline-2,9-dicarboxylate) molecular WOC with 4-vinylpyridine axial ligands was immobilized on the glassy carbon electrode surface by electrochemical polymerization. Electrochemical kinetic studies revealed that this homocoupling polymer catalyzes water oxidation through a bimolecular radical coupling pathway, where interaction between two Ru(pda)-oxyl moieties (I2M) forms the O-O bond. The calculated barrier of the I2M pathway by density-functional theory (DFT) is significantly lower than the barrier of a water nucleophilic attack (WNA) pathway. By using this polymerization strategy, the Ru centers are brought closer in the distance, and the O-O bond formation pathway by the Ru (pda) catalyst is switched from WNA in a homogeneous molecular catalytic system to I2M in the polymerized film, providing some deep insights into the importance of third coordination sphere engineering of the water oxidation catalyst.

中文翻译：

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通过第三配位球工程技术转换Ru-pda水氧化催化剂的OO键形成途径。

水氧化是通过电化学和光电化学驱动的水分解或CO2还原产生可再生燃料的重要阳极反应。钌配合物（例如Ru-bda家族）已被证明是高效的水氧化催化剂（WOC），尤其是当它们经历双分子OO键形成途径时。在这项研究中，通过电化学聚合将具有4-乙烯基吡啶轴向配体的新型Ru（pda）型（pda2- = 1,10-菲咯啉-2,9-二羧酸酯）分子WOC固定在玻璃碳电极表面。电化学动力学研究表明，这种均偶联聚合物通过双分子自由基偶联途径催化水氧化，其中两个Ru（pda）-氧基部分（I2M）之间的相互作用形成OO键。通过密度泛函理论（DFT）计算得出的I2M途径的障碍显着低于水亲核攻击（WNA）途径的障碍。通过使用这种聚合策略，Ru中心的距离更近，Ru（pda）催化剂形成的OO键形成路径从均相分子催化系统中的WNA转换为聚合膜中的I2M，从而提供了一些深刻的见解。认识到水氧化催化剂的第三配位领域工程的重要性。