The 3D ultra-thin Cu1-xNixS/NF nanosheet as a highly efficient and stable electrocatalyst for overall water splitting

In recent years, the exploration of efficient and stable noble-metal-free electrocatalysts is becoming increasingly important, used mainly for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, a new ultrathin porous Cu 1-x Ni x S/NF nanosheets array was constructed on the 3D nickel skeleton by two-step method: hydrothermal method and vulcanization method. Through these two processes, Cu 1-x Ni x S/NF has a larger specific surface area than that of foamed nickel (NF) and Cu 1-x Ni x O/NF. The Cu 1-x Ni x S/NF materials show excellent catalytic activity by accelerating the electron transfer rate and increase the amount of H 2 and O 2 produced. The lower overpotential was obtained only 350 mV at 20 mA cm −2 for OER, not only that, but also the same phenomenon is pointed out in HER, optimal Cu 1-x Ni x S/NF presents low overpotentials of 189 mV to reach a current density of 10 mA cm −2 in 1.0 M KOH for HER. Both OER and HER shows a lower Tafel slope: 51.2 mV dec −1 and 127.2 mV dec −1 , subsequently, the overall water splitting activity of Cu 1-x Ni x S/NF was investigated, and the low cell voltage was 1.64 V (current density 10 mA cm −2 ). It can be stable for 14 h during the overall water splitting reaction. These results fully demonstrate that Cu 1-x Ni x S/NF non-precious metal materials can be invoked become one of the effective catalysts for overall water splitting, providing a richer resource for energy storage.