Fe‐Rich Medium‐Entropy Core‐Shell Electrocatalyst for Hydrogen Evolution Reaction Under Large Current Density

Abstract In response to the low stability of expensive Pt under large current, exploring the stable, efficient and cost‐competitive electrocatalyst for hydrogen evolution reaction is crucial for advancing green hydrogen production. Here, a strategy relating to constructing the core‐shell structure with near‐zero‐resistance homogeneous interface is applied to synthesize new Fe‐rich medium‐entropy alloy (MEA) catalyst. This low‐cost sample presents both outstanding durability and catalytic activity with an overpotential of 343.6 mV at 1,000 mA cm⁻² as well as Tafel slope of 67.6 mV dec⁻¹, respectively much lower than benchmark catalyst 20%Pt/C (416.9 mV, 156.8 mV dec⁻¹) in 1.0 m KOH solution. Such properties are attributed to the enhanced reactivity of surface active sites with electrons easy injection from MEA metallic core to MEO (medium entropy oxide) shell via their highly conductive homogeneous interface. In MEO layer, Fe/Ni/Co sites are identified as active centres and their high oxidation is crucial to shift themselves toward deep energy, weakening Metal─H bonding and thereby accelerating hydrogen evolution. This work not only exploits one novel electrocatalyst suitable for industrial high‐current environments but also provides broad application prospects for MEA utilization.