Defect-mediated improved electrochemical performance of WO3 incorporated MnS hetero-nanocomposites for supercapacitor electrodes in ionic electrolytes

Abstract

Here we report synthesis MnS nanoparticles, WO₃ nanorods, and WO₃ incorporated MnS nanocomposites (MnS/WO₃) by a low-cost hydrothermal method for aqueous supercapacitor electrodes. The concentration of WO₃ varied sequentially and was optimized to obtain electrodes with improved capacitive performance for supercapacitor applications. The successful production of MnS/WO₃ nanocomposite was confirmed by XRD analysis, SEM images, and HR-TEM investigations. Incorporating WO₃ nanorods generates defects that enhance microstrain and dislocation density and expand the interlayer spacing. In a standard three-electrode setup, the MnS/WO₃ (5 wt%) nanocomposite exhibits outstanding electrochemical performance, reaching a specific capacitance of 263 F/g while the current density is 0.12 A/g. In two electrode configurations, the MnS/WO₃ (5 wt%) composite provides an energy density of 5.85 Whkg⁻¹ at a power density of 448 wkg⁻¹ with 86 % capacitive retention after completing 6000 charge-discharge cycles. The density functional theory revealed that the Mn-3d and W-5d orbitals produce defect states in the nanocomposite. Theoretical analysis also showed that the incorporation of WO₃ increases the quantum capacitance from 156 F/g to 293 F/g. The combined experimental and theoretical studies using a cost-effective technique will facilitate the development of new supercapacitor electrodes.