High‐Entropy Engineering to Stabilize Single‐Atom Ru Catalysts for Efficient and Durable Water Splitting

Developing efficient and durable electrocatalysts for oxygen and hydrogen evolution reactions (OER/HER) remains fundamentally challenging due to the intrinsic trade‐off between activity and stability. We herein report a high‐entropy‐engineered strategy to stabilize single Ru atoms on FeCoNiCrMn spinel oxides to overcome the dilemma. The resulting catalyst delivers excellent bifunctional activity and stability, revealed by low overpotentials of merely 280 mV at 100 mA cm −2 for OER and 37 mV at 10 mA cm −2 for HER, a low cell voltage of 1.66 V at 1 A cm −2 for anion exchange membrane water electrolyzer and undamped cell performance at 1 A cm −2 for 1500 h. Experimental and theoretical results illustrate that single Ru atoms coordinated by O 4 Cl species are active centers with the lowest theoretical overpotentials for OER and HER. Uniquely, reversible oxyhydroxides reconstructed from spinel oxides occur in the OER process. Meanwhile, Ru single atoms anchored on the oxyhydroxides has much higher dissolution potential than RuO 2 and catalyzes OER following the stable adsorbate evolution mechanism pathway, resulting in excellent stability. This work highlights high‐entropy engineering for stabilizing and activating single‐atom catalysts, offering new insights into rational design of advanced catalysts for future sustainable energy device development.