One-step preparation of molybdenum disulfide/graphene nano-catalysts through a simple co-exfoliation method for high-performance electrocatalytic hydrogen evolution reaction.

HYPOTHESIS: Recently, molybdenum disulfide (MoS2 ) as a new type of catalyst, has been used for hydrogen evolution. In order to overcome the shortcomings of MoS2 , such as poor conductivity and lack of catalytic activity sites, various materials were added to prepare composites, such as graphene with good conductivity.

EXPERIMENTS: In this work, we combined MoS2 with graphene through a very simple liquid-phase salt-assisted co-exfoliation method. The obtained MoS2 /graphene nano-composites have been further applied to electrocatalyst of hydrogen evolution reaction. The influences of different ratio of MoS2 to graphene and different solvents of exfoliation on the electrocatalytic activity for the hydrogen evolution reaction have been investigated in detail.

FINDINGS: In general, the obtained MoS2 /graphene nano-catalysts exhibits the smallest Tafel slope of 61 mV/dec with the exfoliation solvent of isopropanol, and 65 mV/dec in N-methyl pyrrolidone. All the MoS2 /graphene composites exhibit much better catalytic activity than either MoS2 or graphene single substance due to the synergetic effect between MoS2 and graphene nanosheets.