Boosting the electrochemical performance of MoS2 nanospheres-N-doped-GQDs-rGO three-dimensional nanostructure for energy storage and conversion applications

Abstract

The rational designed three-dimensional (3D) molybdenum-disulfide (MoS2) nanostructures have attracted significant research interest as electrode materials for energy conversion and storage applications. Herein, we developed 3D-MoS2 nanospheres and N-doped GQDS (N-GQDs) anchored with reduced graphene oxide (rGO) nanostructure (MoS2-N-GQDs-rGO, MQG) by facile hydrothermal method which was used as an electrode material for supercapacitor and electrochemical water splitting. TEM image reveals that the self-assembly of MoS2 nanospheres were anchored on the surface of rGO-nanosheets without aggregation. The BET surface area of the MQG sample (43.3 m2/g) was 8.8-fold greater than that of MoS2 (4.9 m2/g). The MQG electrode shows an excellent specific-capacitance of 416.5 F/g at 1 A/g which was greater than that of MoS2 (162.7 F/g). Also, 75.8% of its specific-capacitance was retained after 1000 cycles at 2 A/g, indicating its good stability. Moreover, the MQG nanostructure showed the preferable HER activity in 1.0 M KOH solution with a low overpotential of 145 mV at current density of 10 mA/cm2 compared with MoS2 (186 mV). The 3D-nanostructure could improve the conductivity, surface area, ion-diffusion and prevent structural collapse in the electrochemical reaction, further leading to superior electrochemical performance. These results clearly indicate the MQG nanostructure as a highly propitious electrode for supercapacitor and HER applications.