Water oxidation is a primary step in natural as well as artificial photosynthesis to convert renewable solar energy into chemical energy/fuels. Electrocatalytic water oxidation to evolve O₂, utilizing suitable low-cost catalysts and renewable electricity, is of fundamental importance considering contemporary energy and environmental issues, yet it is kinetically challenging owing to the complex multiproton/electron transfer processes. Herein, we report the first cobalt-based pincer catalyst for catalytic water oxidation at neutral pH with high efficiency under electrochemical conditions. Most importantly, ligand (pseudo)aromaticity is identified to play an important role during electrocatalysis. A significant potential jump (∼300 mV) was achieved toward a lower positive value when the aromatized cobalt complex was transformed into a (pseudo)dearomatized cobalt species. The dearomatized species catalyzes the water oxidation reaction to evolve oxygen at a much lower overpotential (∼340 mV) on the basis of the onset potential (at a current density of 0.5 mA/cm²) of catalysis at pH 10.5, outperforming other Co-based molecular catalysts reported to date. These observations may provide a new strategy for the judicious design of earth-abundant transition-metal-based water oxidation catalysts.

中文翻译：

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电水氧化由磷氮O═PN ³ -Pincer钴配合

水氧化是自然和人工光合作用中将可再生太阳能转化为化学能/燃料的第一步。电催化水氧化生成O ₂考虑到当前的能源和环境问题，使用合适的低成本催化剂和可再生电力具有根本的重要性，但是由于复杂的多质子/电子转移过程，它在动力学上具有挑战性。本文中，我们报道了第一种用于电化学条件下高效中性pH催化水氧化的钴基钳型催化剂。最重要的是，已确定配体（假）芳香性在电催化过程中起重要作用。当芳构化的钴配合物转化为（伪）脱芳构化的钴物种时，可实现显着的电位跃迁（〜300 mV），朝向较低的正值。²）在pH 10.5时的催化性能优于迄今为止报道的其他基于Co的分子催化剂。这些发现可能为明智的设计基于地球的过渡金属基水氧化催化剂提供了新的策略。