Constructing Ag Single Atoms and Nanoparticles Co‐Decorated CoO(O)H as Highly Active Electrocatalyst for Oxygen Evolution Reaction under Large Current Density

Abstract Developing highly active and stable electrocatalysts is essential for the large‐scale production of hydrogen from alkaline water. In this work, Ag single atoms and nanoparticles co‐decorated Co hydro(oxy)oxide (Ag SAs&NPs@CoO(O)H) is synthesized by a facile one‐step approach. Notably, the overpotential of Ag SAs&NPs@CoO(O)H is 200 mV at current density of 50 mA cm⁻² during oxygen evolution reaction (OER). Meanwhile, it can display the mass activity of 637.47 A g⁻¹_Ag under 300 mV, which is 212.49 times higher than that of commercial IrO₂. Moreover, the assembled Pt/C // Ag SAs&NPs@CoO(O)H system only requires 1.9 V to reach an industrial current density of 1000 mA cm⁻² in alkaline water electrolyzer and exhibits excellent stability at large current density of 1000 mA cm⁻². Furthermore, in situ Raman spectroscopy analysis coupled with theoretical calculations reveals an novel active site switching mechanism is found on Ag SAs&NPs@CoO(O)H. Specifically, the O* preferentially generates on the Ag NPs and then switches toward the Co³⁺ site in CoO(O)H to produce OOH* and O₂. Meanwhile, the Ag SAs in the lattice of CoO(O)H can exert an inhibitory force on the reconstruction process of CoOOH to Co(OH)₂, resulting in excellent anti‐dissolution stability.