Unlocking High-Efficiency Overall Water Electrolysis Through Structurally Ordered High-Entropy Intermetallics-Confined Few-Layered Graphene

High entropy alloys have attracted great attention due to their diverse compositions and tailorable properties, in which the structurally ordered high-entropy alloys (O-HEA) show more stable electrons on the surface to effectively enhance proton and intermediate transformations than their disordered counterparts. In this study, a structural capsule architecture of ultrasmall O-HEA nanocrystals composed of Pt, Co, Ni, Fe, and Cu uniformly confined by few-layered graphene (PCFNC@Gr) is rationally designed. The PCFNC@Gr exhibits remarkable catalytic performance for both hydrogen evolution and oxygen evolution reaction (HER and OER) with required overpotentials of 52.1 and 280 mV, respectively, at a current density of 10 mA cm⁻², and demonstrates excellent long-term stability in alkaline medium. Theoretical calculation confirms that multiple active surface sites owning the unique electronic states of the ordered PCFNC HEA are key factors to enhance HER and OER activities. The anion exchange membrane water electrolyzer stack employing PCFNC@Gr-based electrodes can operate an industrial current density of 1000 mA cm⁻² at a stack voltage of 1.95 V while maintaining a durability over 1000 h with a high efficiency of 64.5%. This achievement suggests a proof-of-concept for designing potential O-HEA@Gr electrocatalyst as high-performance and low-cost candidates to replace current commercial catalysts.