Manipulating Interfacial Water Via Metallic Pt1Co6 Sites on Self-Adaptive Metal Phosphides to Enhance Water Electrolysis

Abstract

Metallizing active sites to control the structural and kinetic dissociation of water at the catalyst–electrolyte interface, along with elucidating its mechanism under operating conditions, is a pivotal innovation for the hydrogen evolution reaction (HER). Here, a design of singly dispersed Pt–Co sites in a fully metallic state on nanoporous Co₂P, tailored for HER, is introduced. An anion-exchange-membrane water electrolyzer equipped with this catalyst can achieve the industrial current densities of 1.0 and 2.0 A cm⁻² at 1.71 and 1.85 V, respectively. It is revealed that the singly dispersed Pt–Co sites undergo self-adaptive distortion under operating conditions, which form a Pt₁Co₆ configuration with a strongly negative charge that optimizes reactant binding and reorganizes the interfacial water structure, resulting in an improved concentration of potassium (K⁺) ions in the closest ion plane. The K⁺ ions interact cooperatively with H₂O (K·H₂O), which strengthens the Pt–H binding interaction and facilitates the polarization of the H─OH bond, leading to improved HER activity. This study not only propels the advancement of cathodic catalysts for water electrolysis but also delineates a metallization strategy and an interface design principle, thereby enhancing electrocatalytic reaction rates.