Self-Adaptive Nonstoichiometric High-Entropy Intermetallics Enable Durable Oxygen Evolution under Industrial Current Densities.

Abstract

Achieving simultaneous high activity and durability in oxygen evolution reaction (OER) catalysts under industrial current densities remains a critical challenge for scalable hydrogen production. Here, we report a nonstoichiometric high-entropy intermetallic (HEI) catalyst that intrinsically overcomes the activity-stability trade-off through the dynamic self-adaptability of a B2 NiAl-type structure. With a hierarchically porous architecture, the HEI catalyst achieves an ultralow overpotential of 359 mV at 1 A cm^-2 and operates stably for over 2000 h under fluctuating current densities (0.5-2 A cm^-2), outperforming noble RuO₂/IrO₂ benchmarks and numerous state-of-the-art catalysts. Atomic-resolution characterization and theoretical calculations reveal that multicomponent alloying reduces energy barriers, while the compositional elasticity of the nonstoichiometric structure enables an adaptive Al-sacrificing mechanism that suppresses active-site dissolution and reduces lattice oxygen involvement. Furthermore, when integrated into an anion-exchange membrane electrolyzer via 3D printing, the HEI catalytic plate delivers 1 A cm^-2 at a cell voltage of 1.72 V with sustained long-term stability, underscoring its potential for industrial application. This work establishes a universal design principle for robust and scalable electrocatalysts by leveraging the self-adaptive resilience characteristic of nonstoichiometric high-entropy intermetallics.