In this review we discuss at the mechanistic level the different steps involved in water oxidation catalysis with ruthenium-based molecular catalysts. We have chosen to focus on ruthenium-based catalysts to provide a more coherent discussion and because of the availability of detailed mechanistic studies for these systems but many of the aspects presented in this review are applicable to other systems as well. The water oxidation cycle has been divided in four major steps: water oxidative activation, O–O bond formation, oxidative activation of peroxide intermediates, and O₂ evolution. A significant portion of the review is dedicated to the O–O bond formation step as the key step in water oxidation catalysis. The two main pathways to accomplish this step, single-site water nucleophilic attack and O–O radical coupling, are discussed in detail and compared in terms of their potential use in photoelectrochemical cells for solar fuels generation.

中文翻译：

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钌催化水氧化过程中O–O键的形成：单位亲核攻击与O–O自由基偶联

在这篇综述中，我们在机理层面讨论了钌基分子催化剂在水氧化催化中涉及的不同步骤。我们选择专注于钌基催化剂来提供更连贯的讨论，并且由于可以为这些系统提供详细的机理研究，但本综述中介绍的许多方面也适用于其他系统。水氧化循环分为四个主要步骤：水氧化活化，O-O键形成，过氧化物中间体的氧化活化和O ₂进化。审查的很大一部分致力于O-O键形成步骤，将其作为水氧化催化的关键步骤。详细讨论了完成此步骤的两个主要途径，即单点水亲核攻击和O-O自由基偶联，并比较了它们在光电化学电池生产太阳能中的潜在用途。