Tailored d-band states and hierarchical porosity in a multi-site high-entropy alloy unlock efficient H₂O dissociation-diffusion for water splitting under over-boiling conditions

Industrial-level alkaline water electrolysis requires high-efficiency catalysts to achieve rapid water dissociation and hydrogen intermediate migration at an ampere-level current density. However, conventional alloy catalysts lack spatially organized, abundant site functions, resulting in poor coupling between alkaline electrolysis steps. Here, we report a new NiCoFeCuMoW high-entropy alloy (HEA) catalyst prepared by pulse electrodeposition, featuring efficient mass and charge transport. The catalyst features a three-dimensional hierarchically porous framework with tailored surface atomic configurations and chemically differentiated multimetallic motifs, enabling abundant accessible active sites, accelerated transport, and cooperative regulation of reaction intermediates. Density functional theory (DFT) calculations show that Mo/W-richdomains preferentially facilitate H 2 O dissociation, whereas adjacent NiCoFeCuMoW ensembles optimize hydrogen diffusion and intermediate stabilization via regulated d-band states, thereby establishing an efficient dissociation-diffusion cascade. The NiCoFeCuMoW HEA delivers overpotentials of only 36 mV within the hydrogen evolution reaction (HER) while exhibiting 226 mV in the oxygen evolution reaction (OER) operating in alkaline electrolytes at 10 mA cm −2 . Amazingly, the cell delivers an ultra-low electrolyte potential of 1.57 V at 120 °C and 1 A cm −2 , owing to greatly enhanced charge-mass transport and perturbed hydrogen-bond networks in the over-boiling environment, providing a scalable HEA design strategy for ampere-level industrial water splitting. The boosted electrocatalytic acitivity of new HEAs alloy catalyst under over-boiling environment. Download: Download high-res image (204KB) Download: Download full-size image