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

Abstract

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 Cu1-xNixS/NF nanosheets array was constructed on the 3D nickel skeleton by two-step method: hydrothermal method and vulcanization method. Through these two processes, Cu1-xNixS/NF has a larger specific surface area than that of foamed nickel (NF) and Cu1-xNixO/NF. The Cu1-xNixS/NF materials show excellent catalytic activity by accelerating the electron transfer rate and increase the amount of H2 and O2 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 Cu1-xNixS/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 Cu1-xNixS/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 Cu1-xNixS/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.