Preparation Of Nano-molybdenum Disulfide And Performance For Hydrogen Evolution Reaction

With the increasing of world energy crisis, it is very urgent to develop renewable and clean energy alternatives. Hydrogen is seen as one of all alternative fuels that are secure, sustainable and clean. Electrolysing water is seen as one of the efficient ways to produce hydrogen. Up to now, the most effective electrocatalysts for hydrogen evolution reaction are based on Pt-group metals. However, as we know, Pt-group metals are very scarce in the earth and extremely expensive. Scientists have been trying to explore other cheap and abundant materials which are also very active for hydrogen evolution reaction to substitute Pt-group metals. Among these candidates, molybdenum disulfide has received tremendous attention due to earth abundant composition and high activity. But molybdenum disulfide has less active sites and is semiconductor material with poor conductivity. So molybdenum disulfide still presents unsatisfied performance far from Pt-based catalysts. Based on the structural features and problems of molybdenum disulfide, we explored the catalytic performance of molybdenum disulfide by changing the ratio of sulfur to molybdenum, adding surfactants, changeing reaction temperature. The main work is as follows:1 The rose-like CTAB-incorporated molybdenum disulfide ultrathin nanosheets were synthesized using a facile surfactant-assisted hydrothermal approach. Adding CTAB to the hydrothermal process can effectively regulate both structural and electronic benefits by controllable disorder engineering and simultaneous CTAB incorporation in MoS2 catalysts, leading to higher specific surface area, more catalytic active site and better electrical conductivity for improving HER activity. The optimized CTAB-incorporated molybdenum disulfide ultrathin nanosheets exhibited an excellent activity for HER with a small onset potential of 88 mV, a low Tafel slope of 55 mV/dec, and relatively good stability.2 Ammonium molybdate and thiourea were molybdenum source and sulfur source. We synthesized flower flakes by hydrothermal-method(220 ?) and discussed the effect of the ratio of sulfur to molybdenum and the reaction temperature. Results showd that lower ratio of sulfur to molybdenum could induce great changes in morphology of molybdenum disulfide. The flower flakes became flower ball. However, the hydrogen evolution reaction performance significantly reduced. Changing reaction temperature had little effect on the morphology of molybdenum disulfide, but had different effect on hydrogen evolution reaction performance. Finally, we got best hydrogen evolution reaction performance at 200 ?.3 With sodium molybdate and thioacetamide as the precursor, we got agaric-like molybdenum disulfide by hydrothermal at 220 ?. We characterised the structural information, the morphologies and electrocatalytic performance by scanning electron microscopy, X-ray diffraction and electrochemical workstation and explored the effect of thioacetamide concentration, anionic surfactants and cationic surfactant on the agaric-like molybdenum disulfide. The results showd that anionic surfactant had little effect on morphology and electrocatalytic performance. Increasing concentration of sulfur source and adding cationic surfactant can significantly reduce hydrogen evolution performance of molybdenum disulfide.