Interface Engineering Effected Charge Redistribution within High Entropy Alloy‐Metal Heterostructured Catalyst Enables High Performance Anion Exchange Membrane Water Electrolysis

Abstract Development of low‐cost, highly efficient and stable catalysts is critical for the prevalence of anion exchange membrane water electrolysis (AEMWE) technology for green hydrogen production. High entropy alloy (HEA)‐metal heterostructures (HEA‐Mo), taking advantage of the versatile active sites and multiple synergies between constituent elements of HEA and interfacial electronic interactions between HEA and metal, are promising bifunctional catalysts for high‐performance water electrolysis. Here, a FeCoNiCuMo HEA‐Mo heterostructured catalyst is synthesized, through supersaturation‐induced phase separation, for both anode and cathode of an AEMWE. The catalyst exhibits outstanding hydrogen evolution reaction (HER) (η 10 /η 500 of 24/140 mV) and oxygen evolution reaction (OER) (η 10 /η 500 of 175/325 mV) activities in 1 m KOH. The HEA‐Mo//HEA‐Mo based AEMWE delivers an ultrahigh current density of 2207 mA cm −2 at 2.0 V and maintains stable operations at a commercially relevant high current density of 500 mA cm −2 for 100 h with only 3.1% decay, demonstrating its excellent operation stability. HER activities are greatly enhanced through modulation of charge distributions with the decorated Mo, leading to better balanced hydrogen adsorption/desorption, together with the team up of Mo, a strong OH − adsorbent, for enhanced water dissociation to accelerate both the Volmer and Heyrovsky steps.