标题： 吡咯型与吡啶型 M-N-C 催化剂在电催化硝酸盐还原中的关键步骤和不同性能趋势 显示英文标题

标题： The Key Steps and Distinct Performance Trends of Pyrrolic vs. Pyridinic M-N-C Catalysts in Electrocatalytic Nitrate Reduction

摘要： 电化学硝酸盐还原反应(NO3RR)为常温下合成氨提供了一种可持续的途径。 尽管金属-氮-碳(M-N-C)单原子催化剂已被视为NO3RR的有前途的候选材料，但其催化行为背后的结构-活性关系仍有待阐明。 通过系统分析已报道的实验数据以及在可逆氢电极(RHE)尺度上的pH场耦合微动力学建模，我们发现，协调依赖性活性源于由金属-中间体相互作用所控制的不同缩放关系。 M-N-吡咯型催化剂在氨生产中表现出更高的转换频率，而M-N-吡啶型催化剂则在活性火山图上表现出更宽的活性范围。 同时，硝酸盐的吸附和质子化步骤，在许多先前的报告中常被忽略和/或假设为同时发生，被确定为NO3RR的速率决定步骤(RDS)。 值得注意的是，我们随后的实验验证在中性和碱性条件下确认了理论预测。 本研究为解释M-N-C催化剂在NO3RR中的电催化活性提供了全面的机制框架，表明经典的热力学限制电位模型不足以准确捕捉RDS以及不同材料的催化性能趋势(即使是在M-N-吡咯型和M-N-吡啶型催化剂上)。 这些发现为NO3RR的反应机制提供了全新的见解，并建立了电催化合成氨的基本设计原则。 显示英文摘要

摘要： Electrochemical nitrate reduction reaction(NO3RR)offers a sustainable route for ambient ammonia synthesis. While metal-nitrogen-carbon (M-N-C) single-atom catalysts have emerged as promising candidates for NO3RR, the structure-activity relations underlying their catalytic behavior remain to be elucidated. Through systematic analysis of reported experimental data and pH-field coupled microkinetic modelling on a reversible hydrogen electrode (RHE) scale, we reveal that the coordination-dependent activity originates from distinct scaling relations governed by metal-intermediate interactions. M-N-Pyrrolic catalysts demonstrate higher turnover frequencies for ammonia production, whereas M-N-Pyridinic catalysts exhibit broader activity ranges across the activity volcano plot. Meanwhile, the adsorption and protonation of nitrate, which is a step often dismissed and/or assumed to be simultaneous in many previous reports, is identified to be the rate-determining step (RDS) in NO3RR. Remarkably, our subsequent experimental validation confirms the theoretical predictions under both neutral and alkaline conditions. This study offers a comprehensive mechanistic framework for interpreting the electrocatalytic activity of M-N-C catalysts in NO3RR, showing that a classical thermodynamic limiting-potential model is not sufficiently accurate to capture the RDS and the catalytic performance trends of different materials (even on M-N-Pyrrolic and M-N-Pyridinic catalysts). These findings provide brand new insights into the reaction mechanism of NO3RR and establish fundamental design principles for electrocatalytic ammonia synthesis.