Robust and Promising Electrocatalytic Oxygen Evolution Reaction by Activated Cu–Co–B Amorphous Nanosheets

The challenge to develop a highly efficient and affordable electrocatalyst for the oxygen evolution reaction (OER) could be fulfilled by a newly developed transition metal boron amorphous alloy electrocatalyst. This could successfully improve the overall efficiency of the electrochemical water splitting. Herein, we demonstrate the development of an entirely new Cu–Co–B amorphous alloy nanosheet (NS), which can act as an industrially promising electrocatalyst for the OER. Among a series of studied compositions, surface activated CuCo2B NSs with 5–6 nm thickness offer highly promising OER performances with an exceptionally high current density of 1000 mA cm–2 at 270 mV of overpotential (η) in a 1.0 M KOH electrolyte. It can also afford η100 = 204 mV and η500 = 256 mV, which remains intact for 60 h, with the lowest Tafel slope and charge transfer resistance and the highest electrochemically active sites with a promising turnover frequency and 87% Faradaic efficiency. It also fulfills the commercial requirement criteria of the OER process in 30 wt % KOH. Extensive experimental analyses led to a Cu–Co synergistic-based mechanism by the in situ formed active sites for the adsorption of *OH and *OOH reaction species, reconstruction of the catalyst surface by forming a metal hydroxides/oxyhydroxides precatalyst, modulation of electronic structure due to the rich defect nature, and topological disorder of the amorphous catalyst. Density functional theory (DFT) studies reveal that CuCo2B NSs are the most promising candidates for OER due to the lowest barrier for OER and thus the lowest adsorption energies, and the Cu-centers effectively and synergistically enhance the OER.