Tuning structure and capacitive performance of MoS2/rGO nanocomposites via hydrothermal reaction time

In this study, MoS2/rGO nanocomposites were successfully synthesized via a simple hydrothermal method using graphene oxide (GO), sodium molybdate (Na2MoO4.2H2O), and thiourea (CH4N2S) as precursors. The effect of hydrothermal reaction time on the structural evolution and electrochemical performance of the MoS2/rGO nanocomposites was systematically investigated. Structural and chemical characterizations confirmed the successful formation of flower-like MoS2 nanosheets uniformly distributed on the rGO matrix, with the nanoflower size gradually increasing with prolonged hydrothermal treatment. XRD and Raman analyses revealed the formation of hexagonal 2H-MoS2 with enhanced crystallinity at longer reaction times, while HRTEM further confirmed the layered structure with an interlayer spacing of ~0.63 nm corresponding to the (002) plane. Interestingly, XPS analysis revealed the coexistence of mixed 1T/2H MoS2 phases, with the 1T/2H ratio gradually decreasing as the hydrothermal time increased. Electrochemical measurements demonstrated that the capacitive performance of the MoS2/rGO nanocomposites improved with increasing hydrothermal time, achieving a maximum specific capacitance of 175.01 F g⁻¹ at 10 mV s⁻¹ for the MoS2/rGO-24 h electrode. The enhanced electrochemical performance is attributed to the synergistic effect of improved GO reduction and enhanced MoS2 crystallinity. Moreover, the MoS2/rGO-24 h electrode exhibited excellent cycling stability, retaining 84.4 % of its initial capacitance after 10,000 charge–discharge cycles. These results suggest that the MoS2/rGO nanocomposites are promising electrode materials for high-performance supercapacitor applications.