Site‐Dependent Hydrogen Adsorption of Pt Single Atoms for Ampere‐Level Alkaline Hydrogen Evolution

ABSTRACT The intermediate adsorption on single‐atom sites critically governs the catalytic performance of single‐atom catalysts. Site‐specific single atoms exhibit distinct intrinsic properties that modulate their intermediate adsorption behaviors. Herein, we elucidate the site‐dependent hydrogen adsorption of Pt single atoms by anchoring them at oxygen vacancies (Pt V /CoOOH), three‐fold hollow sites (Pt T /CoOOH), and lattice sites (Pt L /CoOOH), respectively. Electrochemical measurements demonstrate Pt T /CoOOH achieves an overpotential of 8 mV at a current density of 10 mA cm −2 and long‐term stability for 1000 h. Anion exchange membrane water electrolyzer (AEMWE) integrated Pt T /CoOOH just required 1.90 V to reach the industrial current density of 1.0 A cm −2 with 1000 h stability time. In situ/operando x‐ray absorption fine structure (XAFS), ambient pressure x‐ray photoelectron spectroscopy (AP‐XPS), attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS), and theoretical calculations collectively demonstrate that Pt T /CoOOH exhibits moderate H 2 O dissociation kinetics and near‐thermoneutral hydrogen binding energy. The optimal hydrogen adsorption facilitated a balanced H adsorption‐H 2 desorption kinetics, thereby contributing to a superior alkaline hydrogen evolution reaction (HER) activity compared to Pt V /CoOOH with weaker hydrogen adsorption and Pt L /CoOOH with stronger hydrogen adsorption. This work proposes a precise synthesis strategy to anchor single atoms at diverse sites and elucidates the influence of site‐dependent intermediate adsorption on catalytic performance.