Carbon-coated molybdenum carbide nanosheets derived from molybdenum disulfide for hydrogen evolution reaction

The design and synthesis of efficient non-noble metal catalyst is important for the practical application of hydrogen evolution reaction (HER) from water electrolysis. In this study, molybdenum carbides were prepared by a novel synthetic method, which involved the first exfoliation of 2D MoS2 based on the principle of cold expansion of water below 4 °C and then carburization of exfoliated MoS2. In this method, MoS2 played roles of morphology template and molybdenum source simultaneously. Carbon-coated molybdenum carbide nanosheets were obtained and confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. The stripping degree of MoS2 was found to have an important influence on physical properties and catalytic performance of molybdenum carbides. Interestingly, Mo2C nanosheets encapsulated in carbon nanotubes were observed when the MoS2 with a high peeling degree was used in the preparation. It showed high activity and good durability towards HER in acid solution.