Cobalt phosphides coated copper oxide nanorod arrays for enhanced overall water splitting

Although water splitting has been recognized as a clean energy technology for producing pure hydrogen (H2) and oxygen (O2), the sluggish kinetics of cathode hydrogen evolution reaction (HER) and anode oxygen evolution reaction (OER) extremely hinder its practical application. Herein, we report the cost-effective fabrication of cobalt phosphides coated copper oxide nanorod arrays supported 3D foam (Co2P@CuO NR/CF) as an efficient electrocatalyst for overall water splitting in alkaline condition. The obtained Co2P@CuO NR/CF demonstrated highly catalytic activity for both HER and OER. It only required a small overpotential of 108 mA cm^-1 for HER and 270 mA cm^-1 for OER to achieve the current density of 10 mA cm^-2 with a low Tafel slope of 69 and 74 mV dec^-1, respectively. Notably, Co2P@CuO NR/CF exhibited excellently stable properties, which resulted in continually producing H2 and/or O2 at least 30 h with maintaining a steady current density of 10 mA cm^-2. This considerable catalytic activity resulted from the large surface area, fast electron transfer and open-channel of 3D core-shell structure, and the synergetic effect between the CuO core and the Co2P shell. Our research is expected to provide a promising strategy to develop efficient HER and OER electrocatalyst towards large-scale practical water splitting.