In situ integrated 2D reduced graphene oxide nanosheets with MoSSe for hydrogen evolution reaction and supercapacitor application

Abstract

The electrochemical hydrogen evolution reaction (HER) and supercapacitor are regarded as promising tools to meet the existing energy demand around the world. The non-noble metals such as Mo, W based dichalcogenide electrocatalysts are considered as highly catalytic active materials due to its chemical stability, active edge sites and tunable electronic structure. Here, we have prepared different Mo and W based dichalcogenides such as molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), molybdenum sulfoselenide (MoSSe), tungsten disulfide (WS2), tungsten diselenide (WSe2) and tungsten sulfoselenide (WSSe) nanostructures as a bifunctional electrode material for HER and supercapacitor application. Further the incorporation of two dimensional (2D) nanosheets such as reduced graphene oxide (rGO) into MoSSe (MoSSe/rGO) or WSSe (WSSe/rGO) has altered the electrically conducting active edge sites to ease out the adsorption of hydrogen. Moreover the obtained composite materials were prepared by simple one pot hydrothermal method and characterized by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) mapping techniques. In HER activity studies, MoSSe/rGO shows a minimum overpotential of 285 mV at 10 mA cm−2 current density with the Tafel slope of 98 mV dec−1. Besides, good cyclic stability property upto 1000 cycles was observed. In supercapacitor studies, MoSSe/rGO composite shows the specific capacitance of 373 Fg−1 at 1 Ag−1 current density. The synergistic effect between MoSSe and rGO nanosheets via electrostatic interaction makes the composite material as strong. As a result, during the cyclic study, among different Mo and W based dichalcogenides, MoSSe/rGO composite electrode shows high stability towards HER and supercapacitor.

Keywords

• Transition metal chalcogenides
• MoSSe
• WSSe
• HER
• Supercapacitor
• rGO