Preparation Of MoS₂/Mo₂C Composite Material And Application In Photoassisted Electrocatalytic Hydrogen Evolution

With the progress of human science and technology and the development of economy,people have payed more and more attention to their survival condition and the environment problem. Due to the low utilization ratio of traditional fossil fuels and the serious problems of environmental pollution, it has become crucial and urgent to seek sustainable and clean energy sources. Hydrogen, as a green fuel, is a promising candidate for traditional petroleum fluels in future. Electrochemical water splitting has attracted much attention due to its high abundance in raw materials. To improve the efficiency of water splitting for hydrogen generation, active catalysts are required. Rare metals, such as platinum, have high efficiency in the hydrogen evolution reaction ?HER?, however, their high cost and scarcity limit their large scale applications. During the past few years, MoS₂ has attracted much attention due to its high abundance, low cost and chemical stability in the acid solution. Although there are a lot of molybdenum disulfide research progress, increasing both the conductivity and active sites of MoS₂ nanostructures simultaneously for efficient HER electro-catalysts still remains a challenging task.In this work, we describe a strategy based on an in situ solid reaction and subsequent hydrothermal reactions to grow MoS₂ nanosheets on N-doped carbon nanotubes ?NCNTs?with Mo₂C nanoparticles embedded in the NCNT walls. By tuning the polymerization temperature and the concentration of aniline, polyaniline ?PANI? thin films were uniformly coated on the MoO3 nanowires. An in situ solid reaction for the formation of MoO2/Mo₂C composite materials was carried out by heating the MoO3/PANI hybrids at 700? for 2 h at an Ar atmosphere. The hydrothermal reaction for the preparation of MoS₂/Mo₂C composite materials was carried out by heating an aqueous solution containing MoO2/Mo₂C composite materials as precursors and thiourea as the sulfur source at 200? for 48 h. The final products have been characterized analysis by scanning electron microscope ?SEM?,transmission electron microscopy ?TEM?, X-ray diffraction ?XRD? and X-ray photoelectron spectroscopy?XPS?. The composites possess abundant active sites for the HER because the thickness of MoS₂ nanosheets is in the range of 1-5 nm, and the MoS₂ nanosheets are grown on the surface of N-doped carbon nanotubes with an angle that allows more active edge sites exposed to the electrolyte. Besides, the spacing ?002? of the basal planes of MoS₂ nanosheets are expanded. This leads to rich-defect in MoS₂ nanosheets, which provides additional active edge sites for the HER.Eelectrocatalytic test results show that, as the electrocatalyst, the hybrid materials exhibit superior activity for the hydrogen evolution reaction, including small overpotential,high exchange current density and good electrochemical stability. On this basis we conducted the photoassisted electrocatalytic test, and test results show that ultrathin MoS₂ nanosheets have a good response to sunlight. Under the irradiation of sunlight, cathodic hydrogen evolution current densities have a good improvement.