电催化析氢概述

Overview of Electrocatalytic Hydrogen Precipitation

摘要: 电催化析氢反应(Hydrogen Evolution Reaction, HER)作为水分解制氢的核心步骤，其反应机理涉及多电子转移与氢中间体的动态吸附–脱附过程。由于电解质溶液pH值直接影响质子来源及反应路径，HER在酸性与碱性介质中遵循不同的动力学机制。本论文通过对比不同pH体系中氢析出反应的路径演变，从微观动力学角度揭示了活性位点的调控机制。特别阐明了氢吸附自由能(ΔG_H*)与催化活性之间的火山型构效关系，该发现为建立催化剂活性描述符提供了理论框架，对设计pH普适性电催化剂具有重要指导意义。催化剂的电子结构(如d带中心位置)、表面活性位点分布及ΔG_H*的协同优化是调控其活性的关键：理想催化剂需平衡氢中间体的吸附强度，以实现快速反应动力学。本文还系统梳理了HER的主要评价参数及典型催化剂体系，以帮助研究者建立对反应过程的全面认知。

Abstract: The reaction mechanism of the electrocatalytic (Hydrogen Evolution Reaction, HER), a core step in hydrogen production from water decomposition, involves multi-electron transfer and dynamic adsorption-desorption processes of hydrogen intermediates. Since the pH of the electrolyte solution directly affects the proton source and reaction pathway, HER follows different kinetic mechanisms in acidic and alkaline media. This thesis reveals the regulatory mechanism of the active site from a microkinetic point of view by comparing the pathway evolution of the hydrogen precipitation reaction in different pH systems. In particular, the volcano type conformational relationship between the hydrogen adsorption free energy (ΔG_H*) and catalytic activity is elucidated. This finding provides a theoretical framework for the establishment of a catalyst activity descriptor, which is an important guidance for the design of pH-pervasive electrocatalysts. The synergistic optimisation of the catalyst’s electronic structure (e.g. d-band centre position), surface active site distribution and ΔG_H* is the key to modulate its activity: the ideal catalyst needs to balance the adsorption strength of the hydrogen intermediates to achieve fast reaction kinetics. In this paper, the main evaluation parameters of HER and typical catalyst systems are also systematically sorted out to help researchers establish a comprehensive knowledge of the reaction process.