Hybridized bimetallic phosphides of Ni–Mo, Co–Mo, and Co–Ni in a single ultrathin-3D-nanosheets for efficient HER and OER in alkaline media

Highly efficient electrocatalysts based on non-noble and earth-abundant elements for overall water splitting are of great significance for sustainable energy conversion and storage. Herein, hybridization of three bimetallic phosphides, nickel-molybdenum (Ni–Mo), cobalt-molybdenum (Co–Mo), and cobalt-nickel (Co–Ni), in single ultrathin-3D-nanosheets on nickel foam (NMCP@NF) was carried out to fabricate an active and robust trimetallic metal-phosphide electrocatalyst for overall electrochemical water splitting. Simple hydrothermal synthesis followed by chemical vapor deposition-based phosphorization was used to fabricate the present catalyst. By using the optimum stoichiometric ratios of metals precursors, NMCP@NF nanosheets were achieved with the best electrical conductivity and high electrochemically active sites, resulting in high electrocatalytic activities with excellent kinetics for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The NMCP@NF exhibited a low overpotential of 88 mV at 10 mA cm⁻² for HER and a low overpotential of 250 mV at 10 mA cm⁻² for OER. The NMCP@NF (+, -) device required a cell voltage of 1.52 V to reach a current density of 10 mA cm⁻² in an alkaline electrolytic solution. The present study demonstrated that NMCP@NF as the best transition metal phosphide for overall water splitting.