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−1Ag 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.