Hydroxyl reinforcement effect on the heterointerfaced Rh/CoP remarkably accelerates hydrogen evolution reaction in alkaline media

The heterointerfaced Rh-CoP/C was designed and evaluated as a robust electrocatalyst towards the alkaline hydrogen evolution reaction (HER), offering an immense playground for an anion exchange membrane water electrolysis (AEMWE). Notably, Rh-CoP/C spontaneously converses to OH-Rh-CoP/C during alkaline HER via hydroxyl (OH) adsorption and its OH reinforcement effect on the alkaline HER performance was deeply explored by density functional theory (DFT) calculations coupled with experimental measurements. The results demonstrate that OH adsorption at the heterointerface not only promotes water dissociation but also creates a pathway for efficient hydrogen spillover to boost hydrogen (H₂) release, thereby obviously enhancing alkaline HER. Moreover, OH adsorption stabilizes the heterointerface by suppressing P atom migration, ensuring long-term structural integrity. In addition, the optimized heterointerfaced OH-Rh/CoP catalyst exhibits excellent alkaline HER activity, achieving an ultralow overpotential of 10 and 186 mV at 20 and 500 mA cm⁻², respectively, even surpassing commercial 20 wt% JM-Pt/C catalyst and most of previously reported noble metal-based catalysts. When deployed in an anion exchange membrane water electrolysis (AEMWE), it requires a low cell voltage of 1.731 V to reach 1 A cm⁻², along with outstanding operational stability over 2100 h with a minimal degradation rate of 61 µV h⁻¹.