Entropy‐Engineered Non‐Precious Perovskite Catalysts for Ampere‐Level Ammonia‐Water Co‐Electrolysis

Abstract Electrocatalytic water splitting is a sustainable route to high‐purity hydrogen, yet its efficiency is hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Replacing OER with the thermodynamically favorable ammonia oxidation reaction (AOR) significantly reduces the energy input required for hydrogen production while simultaneously addressing ammonia utilization. However, progress is limited by the need for expensive noble metal catalysts like PtIr/C and the poor performance of non‐noble alternatives. Herein, a series of perovskite oxide catalysts is reported with tunable B‐site configurational entropy. Among them, the high‐entropy La 0.7 Sr 0.3 (Ni 0.2 Cu 0.2 Co 0.2 Mn 0.2 Fe 0.2 )O 3‐δ (LS5B) catalyst demonstrates exceptional activity and stability for the ammonia‐water co‐oxidation reaction (AWOR), outperforming lower‐entropy analogs. The enhanced performance is attributed to its entropy‐stabilized structure, which generates abundant surface oxygen vacancies and suppresses atomic diffusion, increasing both active site density and structural durability. Density functional theory (DFT) calculations reveal that the high‐entropy configuration lowers the energy barrier for ammonia adsorption and facilitates intermediate formation. In a practical ammonia‐water co‐electrolyzer, LS5B delivers a current density of 2.6 A·cm −2 at 2.0 V, surpassing PtIr/C and representing the best performance to date. A stable operation over 90 h at ampere‐level current demonstrates LS5B's potential for scalable, efficient green hydrogen production via ammonia‐water co‐electrolysis.