Exploring layered nanocomposite of MoS2 and rGO as a highly efficient supercapattery and OER electrocatalyst

Abstract

Electrochemical energy storage (EES) materials with unique nanoarchitectures and charge storage properties are highly desirable as electrode materials for application in supercapattery devices. Supercapatteries can store substantial energy and simultaneously deliver adequate power. Herein, we report a low-temperature hydrothermally synthesized MoS₂@rGO nanocomposite as a candidate electrode material for supercapattery and OER applications. Pristine MoS₂ and rGO have also been studied to understand the changes in the physical and electrochemical properties during the formation of the MoS₂@rGO nanocomposite. Physicochemical characterization was carried out by employing PXRD, FTIR, Raman spectroscopy, XPS, SEM-EDS, HRTEM, SAED and BET analysis, which revealed effective synthesis of the composite materials. The electrochemical performance was evaluated using a three-electrode system in 1 M KOH. MoS₂@rGO (1 : 2.4) displayed superior electrochemical properties compared with its pristine constituents, with the highest specific capacitance of 4503.8 F g⁻¹ at a high current density of 5 A g⁻¹. It delivered an energy density of 72.16 W h kg⁻¹ and a power density of 849.5 W kg⁻¹ at 5 A g⁻¹. It also achieved a high specific power of 1734.8 W kg⁻¹ at a current density of 10 A g⁻¹. Tafel anodic polarization revealed a current density of 638.4 mA cm⁻² at an applied potential of 700 mV. Furthermore, a Tafel slope of 92 mV dec⁻¹ and a current density of 100 mA cm⁻² were achieved at an overpotential of 303 mV. The superior electrochemical behaviour of the nanocomposite could be ascribed to the synergistic effect of MoS₂ and rGO. These results suggest that the MoS₂@rGO (1 : 2.4) nanocomposite is suitable for supercapattery and OER electrocatalysis applications.