Valence Electronic Configuration and Work Function Unify Hydrogen Evolution Kinetics

High Resolution Image Download MS PowerPoint Slide The hydrogen evolution reaction is central to electrochemistry, yet the distinct activity trends separating d-block from s/p-block metals have long eluded a unified mechanistic explanation. Here, we re-evaluate the relationship between exchange current density (log j 0 ) and work function (Φ) using the average data for polycrystalline surfaces, revealing that Groups 4−10 and s/p-block metals collapse onto a single linear correlation, while Group 11−12 metals follow a parallel trend offset by ≈2.15 log units. We propose a unified kinetic framework incorporating two descriptors: work function, which lowers the electron-transfer barrier, and valence electronic configuration, which governs H−H coupling. Metal atoms with at least two exposed half-filled orbitals (Groups 4−10, s/p-block) facilitate direct on-surface coupling. In contrast, Group 11−12 metal atoms, lacking sufficient half-filled orbitals, force a diffusion-mediated pathway, incurring a thermodynamic penalty. By deriving rate equations that explicitly include these material properties, this work may resolve historical ambiguities and offer a quantitative, predictive criterion for the rational design of high-performance electrocatalysts.