Self-supported nanoporous NiCo2O4 nanowires with cobalt–nickel layered oxide nanosheets for overall water splitting

Abstract

Water splitting via the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in producing H₂ and O₂ is a very important process in the energy field. Developing an efficient catalyst which can be applied to both HER and OER is crucial. Here, a bifunctional catalyst, CFP/NiCo₂O₄/Co_0.57Ni_0.43LMOs, has been successfully fabricated. It exhibits remarkable performance for OER in 0.1 M KOH producing a current density of 10 mA cm⁻² at an overpotential of 0.34 V (1.57 V vs. RHE), better than that of the commercial Ir/C (20%) catalyst. Simultaneously, it also exhibits good catalytic performance for HER in 0.5 M H₂SO₄ producing a current density of 10 mA cm⁻² at an overpotential of 52 mV and a Tafel slope of 34 mV dec⁻¹, approaching that of the commercial Pt/C (20%) nanocatalyst. Particularly, CFP/NiCo₂O₄/Co_0.57Ni_0.43LMOs present better durability under harsh OER and HER cycling conditions than commercial Ir/C and Pt/C. Furthermore, an H-type electrolyzer was fabricated by applying CFP/NiCo₂O₄/Co_0.57Ni_0.43LMOs as the cathode and anode electrocatalyst, which can be driven by a single-cell battery. This bifunctional catalyst will be very promising in overall water splitting.