A High-entropy Antiperovskite Nitride Enables Efficient Anion Exchange Membrane Water Electrolysis

Despite the availability of many (oxy)hydroxide-based oxygen evolution reaction (OER) electrocatalysts with favorable intrinsic activity, few perform well in anion exchange membrane water electrolyzers (AEMWEs). Their poor electrical conductivity confines the OER to the boundary between the current collector and electrocatalyst, resulting in poor catalyst utilization. Herein, the use of highly conductive antiperovskite nitride is proposed as a platform to develop robust OER electrodes for AEMWEs with outstanding performance. By growing over nickel foam, high catalyst surface is realized. Under operation conditions, surface reconstruction leads to the formation of a thin layer of metal oxy-hydroxide, which acts as the real catalyst while protecting the bulk nitride from further corrosion, in turn the conductive antiperovskite effectively improves the catalyst utilization due to efficient current collection. By further rational design of the antiperovskite with a high-entropy composition capable of selective dissolution of elements, lattice oxygen participation in the OER catalysis is enhanced, resulting in boosted intrinsic activity. Specifically, FeZnNNiCoV shows a 108-fold increase in OER specific activity compared to low-entropy ZnNNiCo and ultra-high stability at 1 A cm^-2 over 1000 h. The corresponding AEMWE requires a potential of only 1.76 V to reach 1 A cm^-2, making it highly promising for practical applications.