Engineering a vanadium-incorporated MoS2-based 2-based mixed metal dichalcogenide system for improved supercapacitor performance

In this study, we developed a mixed metal dichalcogenide system of molybdenum-vanadium disulfide with the chemical formula Mo1-xVxS2, 1-x V x S 2 , where x = 0.3, 0.5, and 0.7, corresponding to Mo:V ratios of 70:30, 50:50, and 30:70 using a facile one-pot hydrothermal method. This mixed metal structure is expected to influence both the basal plane and the edge plane towards engineering the active sites in the resulting system forming x Mo n+- y V 4+- z S 2- network, which is a crucial for its improved electrochemical performance. Structural studies confirmed the emergence of structural distortion in the system due to the difference in the ionic sizes of Mo and V ions, leading to strain in the lattices. Furthermore, electron microscopic analysis revealed the formation of aggregated nano- petals for bare MoS2, 2 , while these petals self-assembled to form flower-like microspheres upon the introduction of V in the mixed metal (Mo1-xVxS2) 1-x V x S 2 ) systems. Consequently, the Mo 0.5 V 0.5 S 2 delivered a specific capacitance of 492.2 F g- 1 at 1 A g- 1 with substantial capacitance retention of 94 % up to 3000 cycles, which is twofold higher compared to bare MoS2. 2 . Moreover, the fabricated symmetric device achieved an energy density of 19.5 Wh kg- 1 and a maximum power density of 9000 W kg- 1 with capacitance retention of 92.8 and 86.3 % after 5000 and 10,000 charge/discharge cycles, respectively.