In Situ Thermal Synthesis of Inlaid Ultrathin MoS2/Graphene Nanosheets as Electrocatalysts for the Hydrogen Evolution Reaction

Herein, we report a unique thermal synthesis method to prepare a novel two-dimensional (2D) hybrid nanostructure consisting of ultrathin and tiny-sized molybdenum disulfide nano platelets homogeneously inlaid in graphene sheets (MoS2/G) with excellent electrocatalytic performance for HER. In this process, molybdenum oleate served as the source of both molybdenum and carbon, while crystalline sodium sulfate (Na2SO4) served as both reaction template and sulfur source. The remarkable integration of MoS2 and graphene in a well-assembled 2D hybrid architecture provided large electrochemically active surface area and a huge number of active sites and also exhibited extraordinary collective properties for electron transport and H+ trapping. The MoS2/G inlaid nanosheets deliver ultrahigh catalytic activity toward HER among the existing electrocatalysts with similar compositions, presenting a low onset overpotential approaching 30 mV, a current density of 10 mA/cm(2) at similar to 110 mV, and a Tafel slope as small as 67.4 mV/dec. Moreover, the strong bonding between MoS2 nanoplatelets and graphene enabled outstanding long-term electrochemical stability and structural integrity, exhibiting almost 100% activity retention after 1000 cycles and similar to 97% after 100 000 s of continuous testing (under static overpotential of -0.15 V). The synthetic strategy is simple, inexpensive, and scalable for large-scale production and also can be extended to diverse inlaid 2D nanoarchitectures with great potential for many other applications.