Hydrogen evolution reaction (HER) plays an indispensable role in realizing the hydrogen economy. Regardless of great efforts devoted to investigating its reaction mechanism, no unified conclusion has been reached to explain the pH-dependent kinetics. In this study, a full atomistic Pt(111)/water interfacial model is constructed where pH-dependent behaviors of HER, including Pt-H vibrations, hydrogen binding energy (HBE), and reaction kinetics are examined. In good accordance to previous experimental results, weaker HBE and Pt-H vibration are observed as pH increases. The thermodynamic and kinetic simulations of HER at Pt(111)/water interfaces indicate that HER in acidic media follows the Volmer-Tafel/Heyrovsky pathway with the second step being the rate-determining step (RDS), while it proceeds via the Volmer-Tafel pathway with water dissociation being the RDS in alkaline. The different proton sources and surface properties in acid and alkaline solutions alter HBEs and reaction pathways as well as activation energy barriers. Our full atomistic simulation mimics the electrochemical interface effectively and provides adequate understandings of HER mechanisms at universal pHs, which can be extended into studying other electrochemical reactions.

析氢反应（HER）在实现氢经济方面发挥着不可或缺的作用。尽管致力于研究其反应机理，但尚未得出统一的结论来解释 pH 依赖性动力学。在这项研究中，构建了一个完整的原子 Pt(111)/水界面模型，其中检查了 HER 的 pH 依赖性行为，包括 Pt-H 振动、氢结合能 (HBE) 和反应动力学。与先前的实验结果很好地一致，随着 pH 值的增加，观察到较弱的 HBE 和 Pt-H 振动。HER 在 Pt(111)/水界面的热力学和动力学模拟表明，酸性介质中的 HER 遵循 Volmer-Tafel/Heyrovsky 途径，第二步是速率决定步骤 (RDS)，而它通过Volmer-Tafel途径进行，水离解是碱性的RDS。酸和碱溶液中不同的质子源和表面性质会改变 HBE 和反应途径以及活化能垒。我们的全原子模拟有效地模拟了电化学界面，并提供了对通用 pH 值下 HER 机制的充分理解，这可以扩展到研究其他电化学反应。