Designing layered arrangement of cobalt-molybdenum bimetallic phosphide particles with different sizes on Ni foam for efficient overall water splitting

A reasonable design of excellent bifunctional catalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an effective strategy for large-scale hydrogen production. In this study, a two-stage electrodeposition method was used to design and prepare a crystalline-amorphous structure CoMo-P layered particles of different sizes on a nickel foam (NF) substrate. Electron rearrangement at the Co/Co3Mo2P@CoMoO4 heterogeneous interface can reduce the reaction energy barrier for HER and OER, and accelerate the catalytic reaction kinetics. The doping of Mo can promote the synergistic effect between Co and Mo, thereby optimizing the Gibbs free energy of hydrogen adsorption. This layered arrangement of different size particles greatly improves the active area of the catalyst, thus increasing the number of active sites of the catalyst. Therefore, the prepared transition metal phosphides (TMPs) CoMo-P/NF catalyst showed excellent catalytic activity and electrolytic water stability in alkaline media. In 1 M KOH solution, achieving a current density of 10 mA cm−2 only required overpotentials of 40 mV for HER and 278 mV for OER, respectively. The cell voltage required for the CoMo-P/NF||CoMo-P/NF electrolytic cell is only 1.53 V at 10 mA cm−2 without iR compensation. The excellent catalytic activity and stability of the CoMo-P/NF catalyst are attributed to its unique layered particle structure, rich crystalline-amorphous interface active sites, and the mechanical stability achieved by firmly anchoring the catalyst to the nickel foam. This study provides a reference for the rapid, efficient, and environmentally friendly preparation of high-activity water splitting catalysts with large surface areas.