Supercapacitors and energy conversion structures based on WS₂ and MoS₂ disulfides

In this paper, disulfides WS₂ and MoS₂ were successfully prepared using thermal decomposition and utilised for fabrication of supercapacitor- and water splitting electrodes. Both, energy storage and conversion performances of these electrodes were compared with electrodes prepared with commercial MoS₂, WS₂, and activated carbon (AC). The electrochemical characterisation confirmed the pseudocapacitive character of disulfide-based supercapacitor electrodes. A strong influence of the scan rate on the specific capacitance was found, which is due to the diffusion of ions and the pseudocapacitive nature of charge storage. A specific capacitance of 405 mF/cm² at 10 mV/s scan rate was achieved on MoS₂ structures prepared by thermal decomposition. This value is 3.5-times greater than the capacitance achieved on commercial MoS₂ and 6.8-times greater than capacitance achieved on structures with activated carbon. A specific capacitance of 396 mF/cm² at 10 mV/s scan rate was achieved on WS₂ structures prepared by thermal decomposition, which was 2.2 and 6.7-times greater than the capacitance achieved on commercial WS₂ and AC based electrodes, respectively. Water-decomposition structures showed greater catalytic activity of thermally decomposed disulfides for HER compared to commercial materials and AC. The study showed a high perspective of MoS₂ and WS₂ prepared by thermal decomposition for energy storage applications by means of supercapacitors and energy conversion trough water electrolysis and hydrogen generation.