Coupled plasma etching and electrodeposition of CoP/NiO nanosheets with surface reconstruction for water-splitting

Abstract

Optimization of electrode materials is vital for energy iteration. Electrodes must be economically viable, straightforward, and robust. Herein, high-energy N₂ plasma surface etching was used to etch commercial nickel foam (NF) in situ to create a nanosheet array. The latter could utilize Ni species on NF and achieve atom economy. The in situ generated NiOOH during electrochemical activation could act as the active center for oxygen evolution, whereas the electrodeposited CoP surface coating layer introduced Co and P as active sites to promote hydrogen evolution. The CoP/PNF composite exhibited exceptional bi-functional electrocatalytic capability for the HER and OER, achieving current densities of 20 and 500 mA cm⁻² at overpotentials of 98 and 192 mV, respectively, in the HER. Moreover, overpotentials of 271 and 343 mV were required to achieve current densities of 20 and 500 mA cm⁻², respectively, in the OER. Moreover, CoP/PNF as bi-functional electrodes surpassed the performance of commercial IrO₂‖Pt and most high-end electrocatalysts for large-current water-splitting. Furthermore, surface reconstruction during water electrolysis was studied, which led to the renewal of active sites and promoted long-term stability. This approach is economically feasible, environmentally friendly, and readily scalable. We have provided a novel design strategy for durable and efficient electrocatalysts applied for industrial-scale water electrolysis.