塔菲尔方程
氢铵
动力学
电化学
质子化
化学
雷亚克夫
电化学动力学
化学动力学
脱质子化
铂金
分子动力学
无机化学
物理化学
计算化学
分子
催化作用
有机化学
离子
电极
物理
量子力学
原子间势
作者
Guangyan Zhong,Tao Cheng,Aamir Shah,Chengzhang Wan,Zhihong Huang,Sibo Wang,Tianle Leng,Yu Huang,William A. Goddard,Xiangfeng Duan
标识
DOI:10.1073/pnas.2208187119
摘要
Electrocatalytic hydrogen evolution reaction (HER) is critical for green hydrogen generation and exhibits distinct pH-dependent kinetics that have been elusive to understand. A molecular-level understanding of the electrochemical interfaces is essential for developing more efficient electrochemical processes. Here we exploit an exclusively surface-specific electrical transport spectroscopy (ETS) approach to probe the Pt-surface water protonation status and experimentally determine the surface hydronium pKa [Formula: see text] 4.3. Quantum mechanics (QM) and reactive dynamics using a reactive force field (ReaxFF) molecular dynamics (RMD) calculations confirm the enrichment of hydroniums (H3O[Formula: see text]) near Pt surface and predict a surface hydronium pKa of 2.5 to 4.4, corroborating the experimental results. Importantly, the observed Pt-surface hydronium pKa correlates well with the pH-dependent HER kinetics, with the protonated surface state at lower pH favoring fast Tafel kinetics with a Tafel slope of 30 mV per decade and the deprotonated surface state at higher pH following Volmer-step limited kinetics with a much higher Tafel slope of 120 mV per decade, offering a robust and precise interpretation of the pH-dependent HER kinetics. These insights may help design improved electrocatalysts for renewable energy conversion.
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