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氢氧电催化反应是氢能源体系的重要反应,其热力学和动力学直接影响水解制氢和燃料电池的能量效率和功率密度.过去十多年来,基于量子化学的理论计算在电催化剂设计及电催化反应机理研究中得到广泛应用.结合文献结果,本文介绍了近年来在Pt基催化剂表面氢、氧电催化反应理论计算研究中获得的结果和认识.在研究中重点对反应中间体吸附结构、覆盖度及其对反应路径和动力学的影响机制进行了分析.结果指出,反应中间体的吸附特性不仅会影响反应控制步骤的活化能,同时通过改变表面反应活性位的结构和数量影响表面反应速率.对火山顶点附近的Pt基催化剂,简单计算的吸附能不足以准确预测催化剂活性,必须考虑吸附质的覆盖度和吸附结构的影响.在此认识基础上,根据表面反应自由能及速率与关键中间体吸附能、覆盖度及电极电势的关系建立微观动力学模型,利用密度泛函理论计算获得关键吸附中间体在催化剂表面的电化学吸附等温线(吸附结构及覆盖度与电极电势的关系),确定反应活性位、反应路径和动力学,构建催化活性与吸附能的关系曲线,预测催化剂的表面结构及尺寸效应,并对一些重要实验结果进行解释.
Hydrogen and oxygen electrocatalytic reaction is an important reaction of hydrogen energy system, and its thermodynamics and kinetics directly affect the energy efficiency and power density of hydrogen production and fuel cell hydrolysis.In the past decade, based on the theoretical calculations of quantum chemistry in electrocatalyst design and Electrocatalytic reaction mechanism has been widely used.According to the literature results, this paper introduces the results and understanding obtained in the theoretical calculation of hydrogen and oxygen electrocatalytic reaction on Pt-based catalyst surface in recent years.In this study, we focused on the adsorption of the intermediate structure , Coverage and its mechanism of reaction path and kinetics were analyzed.The results showed that the adsorption characteristics of the reaction intermediates not only affect the activation energy of the reaction control step but also affect the surface by changing the structure and number of reactive sites on the surface Reaction rate.For the Pt-based catalyst nearby the volcano peak, the simple calculation of the adsorption energy is not enough to accurately predict the activity of the catalyst, we must consider the coverage of the adsorbate and the influence of the adsorption structure.Based on this understanding, according to the surface reaction free energy and rate And the key intermediates adsorption energy, coverage and electrode potential to establish a micro-dynamic Model, the electrochemical adsorption isotherm (the relationship between the adsorption structure and the coverage and the electrode potential) of the key adsorptive intermediates on the catalyst surface is obtained by means of the density functional theory calculation, and the reactive sites, reaction pathways and kinetics are determined to construct the catalytic activity And adsorption energy curve to predict the catalyst surface structure and size effects, and to explain some of the important experimental results.