Tuning Overall Water Splitting on an Electrodeposited NiCoFeP Films

Abstract The regulation of geometric and electronic structures is very important to transition metal phosphides with high catalytic properties. Herein, nanofilms consisting of NiCoFeP nanospheres were electrochemically deposited onto 3D Ni foam for the catalysis of water splitting. Depending on the amount of iron, the NiCoFeP nanocatalysts exhibit different surface topographies and chemical binding energies, which have a great influence on electrochemical performances. The optimal NiCoP‐0.01 M Fe films show robust bifunctional electrocatalytic activities with an overpotential of 118 mV (10 mA cm −2 ) for the hydrogen evolution reaction (HER) and 300 mV (50 mA cm −2 ) for the oxygen evolution reaction (OER). The overall water splitting employing this proposed nanocatalyst at both electrodes only presents a cell voltage of 1.60 V at the current density of 10 mA cm −2 , far lower than that (1.73 V) with the commercial Pt/C cathode and RuO 2 anode combination.