Developing highly active oxygen evolution reaction (OER) catalysts with fast OER kinetics is crucial for disruptively changing the energy technology, where unlocking of the catalytic origin is the key to the rational design of high-performance catalysts. Herein, a Co-based heterostructure consisting of cobalt (Co) and molybdenum carbide (Mo₂C) nanoparticles in a 2D morphology is purposely designed as an OER precatalyst. At the initial stage of the OER in alkaline solution, the fast phase transition of Co metal into γ-phase cobalt oxyhydroxide (γ-CoOOH) in the presence of Mo₂C gives rise to a Mo-enriched surface of the defective γ-CoOOH. This significantly raises the OER kinetics and gives an almost 90% enhancement in catalytic activity per metal site. Interestingly, the phase transition to γ-CoOOH and Mo-enriched surface reconstruction are potential-dependent and are accelerated at 1.4 V, as revealed by in situ Raman spectroscopy as well as ex situ scanning transmission electron microscopy studies. Potential-dependent X-ray photoelectron spectroscopy analyses and methanol oxidation experiments further confirm that the Mo enrichment into the defective CoOOH surface promotes electron flow from Mo to Co sites via the bridging oxygen, greatly benefiting the electrostatic adsorption of OH^– ions and smoothing the subsequent OER steps.

中文翻译：

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异质结构化Co-Mo ₂ C预催化剂中γ-CoOOH的电位依赖性相变和富Mo表面重构可实现水氧化

开发具有快速OER动力学的高活性氧释放反应（OER）催化剂对于颠覆性地改变能源技术至关重要，在这种技术中，催化源的解锁是合理设计高性能催化剂的关键。在此，特意将由钴（Co）和碳化钼（Mo ₂ C）纳米颗粒组成的二维形态的Co基异质结构设计为OER预催化剂。在碱性溶液中OER的初始阶段，在Mo ₂的存在下，Co金属快速相转变为γ相钴羟基氧化物（γ-CoOOH）C产生缺陷的γ-CoOOH的富Mo表面。这显着提高了OER动力学，并且每个金属位点的催化活性提高了近90％。有趣的是，如原位拉曼光谱和非原位扫描透射电子显微镜研究所揭示的，向γ-CoOOH的相变和富Mo的表面重建是电位依赖性的，并在1.4 V时加速。电位依赖性X射线光电子能谱分析和甲醇氧化实验进一步证实，在Mo富集到有缺陷的CoOOH表面促进电子经由桥接氧从沫流入钴位点，极大地受益OH的静电吸附^-离子和平滑随后OER步骤。