Toward feasible single atom-based hydrogen evolution electrocatalysts via artificial ensemble sites for anion exchange membrane water electrolyzer

Approaching an efficient anion exchange membrane water electrolyzer (AEMWE) with satisfactorily high kinetics in the alkaline hydrogen evolution reaction (HER) is desired. We design an advanced platinum (Pt) single atom (SA)-based electrocatalyst by incorporating the Ni nanoparticle as an artificial ensemble site adjacent to Pt SA. The designed Pt SA electrocatalyst achieves higher areal current density (500 mA cm⁻² at 1.8 V) in the single cell of the AEMWE and better cell voltage stability than the Pt/C electrocatalyst. The Ni nanoparticle assists in separating the binding sites of H* and OH*, in which Ni atoms provide adsorption sites for H*, while OH* adsorbs on the Pt SA. This separation effect drastically accelerates the energy barrier required for the water dissociation reaction in the Volmer step and simultaneously optimizes the H* and OH* binding energy, which extremely enhances the alkaline HER kinetics, thereby demonstrating the feasibility of Pt SA electrocatalysts for AEMWE.