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.