用于直接丙烯环氧化的金属-氮-碳电催化剂的多维度设计
Multidimensional Design of Metal-Nitrogen-Carbon Electrocatalysts for Direct Propylene Epoxidation
AI总结：
本研究针对直接丙烯环氧化的选择性调控难题，通过多维度设计策略，确定CoPc-NH2-CNT为最优催化剂，实现创纪录的70%-80%环氧丙烷法拉第效率。
AI中文摘要：
环氧丙烷是一种重要的工业化学品，其当前生产依赖于危险的氯基或过氧化物基氧化剂。以水为氧源的直接电化学环氧化提供了一种可持续的替代方案，但控制氧原子转移以对抗竞争的析氧反应仍是一个根本性挑战。本研究表明，丙烯环氧化选择性无法仅用氧结合能描述，而是由氧吸附、零电荷电势和施加电势共同调控。通过理论计算与pH场耦合的微动力学建模，对41种金属-氮-碳单原子催化剂进行分析，首先确定了最优氧结合窗口，并发现钴是最适宜的金属中心。随后研究发现，外围取代基可调控零电荷电势，同时在很大程度上保留最优氧吸附能，从而提供了一个独立的设计维度，进一步优化已具优势的钴活性位点。这种顺序多维度设计策略确定CoPc-NH2-CNT为最优催化剂，在环境条件下的水性电解质中，其直接丙烯环氧化的环氧丙烷法拉第效率达到创纪录的70%-80%。这些结果确立了界面静电学作为电催化中控制选择性氧原子转移的独立可调控设计维度。
英文摘要：
Propylene oxide is a major industrial chemical whose production currently relies on hazardous chlorine- or peroxide-based oxidants. Direct electrochemical epoxidation using water as the oxygen source offers a sustainable alternative, but controlling oxygen-atom transfer against the competing oxygen evolution reaction remains a fundamental challenge. Here, we show that propylene epoxidation selectivity cannot be described by oxygen binding energy alone, but is jointly governed by oxygen adsorption, the potential of zero charge, and applied potential. By combining theoretical calculations with pH-field-coupled microkinetic modeling across 41 metal-nitrogen-carbon single-atom catalysts, we first identified an optimal oxygen-binding window and Co as the most favorable metal center. We then found that peripheral substituents can tune the PZC while largely preserving the optimal oxygen adsorption energetics, thereby providing an independent design dimension to further optimize the already favorable Co active site. This sequential, multidimensional design strategy identified CoPc-NH2-CNT as the optimal catalyst, delivering a record PO Faradaic efficiency of 70-80 percent for direct propylene epoxidation in aqueous electrolyte under ambient conditions. These results establish interfacial electrostatics as an independently tunable design dimension for controlling selective oxygen-atom transfer in electrocatalysis.
