Decoupling the scaling relationship of water dissociation and hydroxyl desorption via Ru/Cr2O3 heterostructure for efficient alkaline hydrogen evolution at industrial current density

Efficient alkaline hydrogen evolution reaction (HER) catalysts are critical for anion exchange membrane water electrolysis (AEMWE). However, the intrinsic scaling relationship between water dissociation and OH desorption fundamentally impedes designing catalysts requiring concurrent superior water dissociation and facile OH desorption. Here, we engineer a superhydrophilic Ru/Cr2O3 heterostructured electrocatalyst through in situ confinement of Ru nanoparticles (5–10 nm) within a Cr2O3 matrix. Acting as a Lewis acid, the Cr2O3 component provides alternative sites for water dissociation, accelerating the Volmer step kinetics and downshifting the Ru d-band center via interfacial charge transfer, while simultaneously adsorbing OH− to form a surface-bound Lewis base that repels excess OH− from Ru sites, thereby suppressing hydroxyl over-adsorption. Concurrently, the superhydrophilic surface architecture promotes efficient hydrogen bubble release, thereby reducing mass transport resistance. As a result, the Ru/Cr2O3 heterostructured electrocatalyst exhibits an ultralow overpotential of 36.7 mV at 10 mA cm−2 and a Tafel slope of 33.2 mV dec−1. Integrated into an AEMWE device, the electrode delivers 500 mA cm−2 for 2000 h in 1.0 M KOH, underscoring its industrial viability (hydrogen production energy consumption per cubic meter (EW): 3.94 kW h m−3; electricity-to-hydrogen energy conversion efficiency (ηETH): 89 %@80 °C).