In this study, the high catalytic reactivity of ruthenium phosphide (RuP₂) has been identified by first-principles density functional theory (DFT) calculations for the electrocatalytic hydrogen evolution reaction (HER). Complex surface reconstructions are considered by applying the ab initio grand canonical Monte Carlo (ai-GCMC) algorithm, efficiently providing a sufficient phase-space exploration of possible surfaces. Combined with surface-phase Pourbaix diagrams, we are able to identify the actual surfaces that obtained under specific experimental environments, thus leading to a more accurate understanding of the nature of the active sites and the binding strength of adsorbates. Specifically, through hundreds of surface reconstructions and hydrogenation states generated with ai-GCMC, we identify the most favorable surface phases of RuP₂ under aqueous acidic conditions. We discover that the HER activity is determined by multiple surfaces with different stoichiometries within a narrow electrode potential window. Low HER overpotential (η) has been found for each of the identified surfaces, as low as 0.04 V. High H-coverage reconstructed surfaces have been discovered under acidic conditions, and the surface Ru sites introduced by additional Ru adatoms or exposed by P-vacancies serve as the active sites for HER based on their nearly reversible H binding. This work provides atomistic insights into the origin of high HER activity on RuP₂ by exploring the dynamic surface phases of electrocatalysts and features a generalizable method to explore the reconstructed/hydrogenated surface space as a function of experimental conditions.

中文翻译：

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通过 Ab Initio Grand Canonical Monte Carlo 揭示 RuP2 上的电催化析氢反应通路


在本研究中，磷化钌 （RuP₂） 的高催化反应性已通过电催化析氢反应 （HER） 的第一性原理密度泛函理论 （DFT） 计算确定。通过应用 ab initio grand canonical Monte Carlo （ai-GCMC） 算法来考虑复杂的表面重建，有效地提供了对可能表面的充分相空间探索。结合表面相 Pourbaix 图，我们能够识别在特定实验环境下获得的实际表面，从而更准确地了解活性位点的性质和吸附物的结合强度。具体来说，通过使用 ai-GCMC 生成的数百种表面重建和氢化态，我们确定了 RuP₂ 在酸性水条件下最有利的表面相。我们发现 HER 活性是由狭窄电极电位窗口内具有不同化学计量的多个表面决定的。已发现每个已识别表面的低 HER 过电位 （η），低至 0.04 V。在酸性条件下发现了高 H 覆盖率重建表面，并且由额外的 Ru 原子引入的表面 Ru 位点或由 P 空位暴露的表面 Ru 位点作为其基于其几乎可逆的 H 结合的活性位点。这项工作通过探索电催化剂的动态表面相，为 RuP₂ 上高 HER 活性的来源提供了原子见解，并采用了一种可推广的方法来探索作为实验条件函数的重建/氢化表面空间。