An electrodeposited cobalt-selenide-based film as an efficient bifunctional electrocatalyst for full water splitting

Design and development of noble metal-free, active and bifunctional electrocatalysts is crucial for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in the full water splitting process. Herein, an amorphous cobalt-cobalt oxide/cobalt selenide composite film (CoOx-CoSe) has been fabricated directly on a three-dimensional macro-porous Ni foam (NF) substrate by a facile electrodeposition method, which shows remarkable activity and good long-term stability as an efficient bifunctional electrocatalyst for the OER and HER under alkaline conditions. In 1.0 M KOH, this catalyst as a robust 3D O-2-evolving anode can achieve 100 mA cm(-2) and 500 mA cm(-2) only at overpotentials of 300 mV and 380 mV, respectively. When used as a HER catalyst, similarly, this electrode shows excellent catalytic performance, which needs an overpotential of 90 mV to deliver 10 mA cm (2). This bifunctional electrode can allow an alkaline electrolyzer to obtain a water-splitting current density of 20 mA cm(-2) at a cell voltage of around 1.66 V, which offers potential applications in the field of water splitting.