Facile synthesis of molybdenum disulfide/nitrogen-doped graphene composites for enhanced electrocatalytic hydrogen evolution and electrochemical lithium storage

A facile one-pot hydrothermal route with the mediation of ionic liquid (IL, [BMIM]BF4) is presented to synthesize MoS2/nitrogen-doped graphene (MoS2/NG-IL) composites. It is found that as-prepared MoS2/NG-IL composites exhibit that the de-layered MoS2 sheets with more exposed edge sites and defects are well anchored on the N-doped graphene. Due to the synergism between de-layered MoS2 and N-doped graphene, MoS2/NG-IL composites exhibit better electrochemical performances for hydrogen evolution reaction (HER) and reversible lithium storage in comparison with MoS2. Especially, when 1.0 mL of IL is added in hydrothermal solution, the obtained MoS2/NG-IL10 displays very high electrocatalytic activity for HER with a low onset overpotential of 80 mV and a small Tafel slope of 48.0 mV/dec in 0.5 M H2SO4. As anode of lithium ion battery, MoS2/NG-IL10 delivers a reversible capacity as high as 1169 mAh g−1 at 100 mA g−1 and enhanced rate capability of 782 mAh g−1 at 1000 mA g−1. After 800 cycles, a reversible capacity of about 800 mAh g−1 at 500 mA g−1 can be retained, indicating its excellent cyclic stability.