One-Pot Rapid Synthesis of Mo(S,Se)(2) Nanosheets on Graphene for Highly Efficient Hydrogen Evolution

The electrocatalytic hydrogen evolution reaction (HER) is known to be an important technique for efficient hydrogen production, and the development of a highly active electrocatalyst with lower overpotential is a key issue. In this study, we demonstrated the rapid, one-pot synthesis of highly active molybdenum dichalcogenide/reduced graphene oxide (Mo(S,Se)/rGO) electrocatalysts from cost-effective and environmentally friendly substances using reductive supercritical conditions. We found that edge-rich MoS2 is synthesized under a high-density ethanol condition and successfully controlled the composition of molybdenum dichalcogenide (MoS2-xSex) nanoflowers at the atomic level by varying the ratio of chalcogen sources. The electrocatalytic HER activity increased with the formation of an edges-rich structure and a solid solution of MoS2 and MoSe2, and by complexing with graphene. The synthesized MoS0.9Se1.1/graphene showed excellent HER properties that can be categorized into the highest-activity group of the previously reported molybdenum dichalcogenide and its composite. Such high electrocatalytic HER performance should be the result of optimizing the hydrogen adsorption free energy of MoS2-xSex and effectively forming conductive paths between MoS0.9Se1.1 and graphene. This rapid one-pot process using supercritical ethanol will be suitable for the mass production of highly active molybdenum dichalcogenide electrocatalysts.