Co-Improvement in Electrocatalytic Hydrogen Evolution Performance of MoS2 by Ni Doping and Graphene Oxide Compounding

Molybdenum disulfide (MoS2) is a promising catalyst for hydrogen evolution through water electrolysis with low cost and high efficiency, but its hydrogen evolution performance can be further improved. Using sodium molybdate (Na2MoO4·2H2O) and thiourea (NH2CSNH2) as raw materials, MoS2 was prepared by the hydrothermal method. Ni-doped MoS2(Ni-MoS2) was prepared by using nickel dichloride dihydrate (NiCl2·2H2O) as a Ni source and doping Ni into MoS2 by the hydrothermal method. Under the conditions of different temperatures (190 °C, 200 °C, and 210 °C) and different Ni doping molar ratios (2%, 3%, and 4%), the optimum temperature and doping ratio of the prepared materials were explored by conducting a hydrogen evolution reaction (HER) by the electrolysis of water. The results showed that the optimum preparation temperature was 200 °C and the optimum molar ratio of Ni doping was 3%. Graphene oxide (GO) was obtained by oxidation of graphite (G), and then Ni-MoS2/GO was prepared by the hydrothermal method with Ni-MoS2 and GO. The performance of HER was tested. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectroscopy (XPS). The results show that the composite Ni-MoS2/GO has good HER performance, which is better than that of MoS2 or Ni-MoS2. In 0.5 M H2SO4 solution, the η10 is as low as 196 mV, the Tafel slope is 122 mV/dec, the Cdl is 13.98 mF/cm2, and it has good stability. The enhancement of electrocatalytic activity is mainly due to the doping of a small amount of Ni, which increases the defects of the catalyst and forms more active sites. GO improves the conductivity of the material. Ni doping and GO compounding promote the HER performance of MoS2.