Enhanced hydrogen spillover at dual-phase high-entropy alloy towards efficient hydrogen production

Developing efficient electrocatalysts is vital for green hydrogen production via water electrolysis. While Pt is highly active for hydrogen evolution reaction (HER), its cost, scarcity, and hydrogen poisoning caused by multi-step reaction accumulation limit its application. The hydrogen spillover effect offers a promising solution, yet its mechanism at metal-metal interfaces that possess lower interfacial charge accumulation remains underexplored compared to metal-semiconductor systems. Herein, a dual-phase FeCoNiVMoMgPt high-entropy alloy was synthesized via molten salt electrochemical deoxidation. The designed elemental interactions and dual-phase structure effectively modulate the electronic structure, optimize the H* adsorption free energy on Pt, and enable spatially decoupled H* adsorption/desorption, facilitating efficient hydrogen spillover. The spatial decoupling of H 2 O adsorption/dissociation and H* adsorption on the Pt poor phase from hydrogen evolution on the Pt rich phase within the dual-phase alloy prevents the over-saturation and poisoning of active Pt centers. This spillover effect significantly enhances H 2 O dissociation, increases surface H* coverage, and accelerates the reaction kinetics. Consequently, the catalyst achieves a low overpotential of 68.2 mV at 500 mA cm −2 and demonstrates exceptional stability for over 500 h in 1 M KOH, significantly surpassing recently reported Pt-based catalysts and commercial Pt/C (186.8 mV). This work underscores the potential of the hydrogen spillover mechanism at engineered metal-metal interfaces for enabling efficient and durable hydrogen production.