Defect Engineering of a High‐Entropy Metallic Glass Surface for High‐Performance Overall Water Splitting at Ampere‐Level Current Densities

Abstract Platinum‐based electrocatalysts possess high water electrolysis activity and are essential components for hydrogen evolution reaction (HER). A major challenge, however, is how to break the cost‐efficiency trade‐off. Here, a novel defect engineering strategy is presented to construct a nanoporous (FeCoNiB 0.75 ) 97 Pt 3 (atomic %) high‐entropy metallic glass (HEMG) with a nanocrystalline surface structure that contains large amounts of lattice distortion and stacking faults to achieve excellent electrocatalytic performance using only 3 at% of Pt. The defect‐rich HEMG achieves ultralow overpotentials at ampere‐level current density of 1000 mA cm −2 for HER (104 mV) and oxygen evolution reaction (301 mV) under alkaline conditions, while retains a long‐term durability exceeding 200 h at 100 mA cm −2 . Moreover, it only requires 81 and 122 mV to drive the current densities of 1000 and 100 mA cm −2 for HER under acidic and neutral conditions, respectively. Modelling results reveal that lattice distortion and stacking fault defects help to optimize atomic configuration and modulate electronic interaction, while the surface nanoporous architecture provides abundant active sites, thus synergistically contributing to the reduced energy barrier for water electrolysis. This defect engineering approach combined with a HEMG design strategy is expected to be widely applicable for development of high‐performance alloy catalysts.