Co−Co Dinuclear Active Sites Dispersed on Zirconium‐doped Heterostructured Co9S8/Co3O4 for High‐current‐density and Durable Acidic Oxygen Evolution

Abstract Developing cost‐effective and sustainable acidic water oxidation catalysts requires significant advances in material design and in‐depth mechanism understanding for proton exchange membrane water electrolysis. Herein, we developed a single atom regulatory strategy to construct Co−Co dinuclear active sites (DASs) catalysts that atomically dispersed zirconium doped Co 9 S 8 /Co 3 O 4 heterostructure. The X‐ray absorption fine structure elucidated the incorporation of Zr greatly facilitated the generation of Co−Co DASs layer with stretching of cobalt oxygen bond and S−Co−O heterogeneous grain boundaries interfaces, engineering attractive activity of significantly reduced overpotential of 75 mV at 10 mA cm −2 , a breakthrough of 500 mA cm −2 high current density, and water splitting stability of 500 hours in acid, making it one of the best‐performing acid‐stable OER non‐noble metal materials. The optimized catalyst with interatomic Co−Co distance (ca. 2.80 Å) followed oxo‐oxo coupling mechanism that involved obvious oxygen bridges on dinuclear Co sites (1,090 cm −1 ), confirmed by in situ SR‐FTIR, XAFS and theoretical simulations. Furthermore, a major breakthrough of 120,000 mA g −1 high mass current density using the first reported noble metal‐free cobalt anode catalyst of Co−Co DASs/ZCC in PEM‐WE at 2.14 V was recorded.