A comparative study of W, V, and Co doping in MoSe₂ for high-performance flexible all-solid-state supercapacitors

The importance of supercapacitor electrode materials and devices undoubtedly stands out in relation to energy storage devices. Selecting a suitable electrode material is crucial for characterization and electrochemical studies. Herein, we report a one-step hydrothermal strategy for the fabrication of molybdenum diselenide (MoSe₂) and 2% tungsten-, vanadium- and cobalt-doped MoSe₂, along with characterization. The structural and morphological changes in the various nanocomposites were confirmed by powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectra. Electrochemical studies reveal significant improvement in specific capacitance, with the Co@MoSe₂ electrode exhibiting the highest specific capacitance of 518 F g^-1 at 1 A g^-1 over a potential window of 0.7 V in 2 M KOH electrolyte solution. The fabricated symmetric supercapacitor device (SSD) delivered a specific capacitance of 127 F g^-1 at 1 A g^-1 over a potential window of 1.4 V. It achieved a maximum energy density of 34.54 W h kg^-1 with a power density of 700 W kg^-1. The device demonstrated excellent durability, with cycling stability of 80% even after 10 000 cycles. The results obtained are highly promising, indicating that these materials hold significant potential for commercial applications in energy storage devices.