Controlled synthesis of NiCoM (M=P, S, Se, O)–Ni3S2–MoS2 hybrid material as environmentally friendly water splitting catalyst

Abstract

The study of high efficiency and low cost catalysts is of great significance to the overall development of electrochemistry. In this paper, NiCoM (M = P, S, Se, O)–Ni3S2–MoS2 hybrid material was prepared by hydrothermal, calcination and hydrothermal three-step reaction method, and its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline environment were studied and compared. The experimental results showed that at 10 mA cm−2, the overpotential of NiCoP–Ni3S2–MoS2 was only 140 mV for HER, while the overpotential of NiCoSe–Ni3S2–MoS2 was only 160 mV for OER. Compared with other catalysts, the activity of NiCoP–Ni3S2–MoS2 and NiCoSe–Ni3S2–MoS2 was higher, and the chemical reagents needed for preparation were cheap and low cost. What is noteworthy is that the morphology of NiCoP–Ni3S2–MoS2 material change after long time stability test for hydrogen evolution reaction, the change makes the performance of the samples toward a better direction. A series of characterization found that the surface of the NiCoP–Ni3S2–MoS2 samples increased more holes and more active site, and did not produce new material after other characterization. Density functional theory calculation shows that the presence of this MoS2 material accelerates the kinetics of hydrogen production and this Co2P material enhances the conductivity of the material. Their synergistic effect makes the NiCoP–Ni3S2–MoS2 catalyst exhibit enhanced hydrogen production activity. The bramble structure of NiCoSe–Ni3S2–MoS2 allows the sample to have more active sites and higher electrocatalytic activity during the OER process. This experiment provides new insights into the preparation of robust water splitting catalysts by simple methods.