Synergistic structural contribution of Co and V doping in nanostructured MoS2 on its electrochemical performance as a supercapacitor electrode

Abstract

Molybdenum disulfide (MoS₂) exhibits intrinsically low electrical conductivity and a tendency to restack, which restrict its effectiveness as an electrode material for energy storage applications. To overcome these challenges, pristine MoS₂ along with its Co- and V-doped derivatives were synthesized via a simple co-precipitation method. The characteristic hexagonal phase remained intact, as confirmed by X-ray diffraction analysis (XRD), while X-ray photoelectron spectroscopy (XPS) revealed stable Mo⁴⁺ and S²⁻ oxidation states and successful incorporation of Co²⁺ and V⁵⁺ ions. Further characterizations employing Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM), and Brunauer–Emmett–Teller (BET) techniques confirmed the presence of active functional groups, clear surface morphology, elemental composition, and surface properties of the material. Electrochemical evaluation in 1 M KOH using Cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD), and Electrochemical impedance spectroscopy (EIS) showed enhanced pseudocapacitive behavior. V- MoS₂ achieved the best performance, with a specific capacitance of 900.3 F/g, corresponding energy density of 107.5 Wh·kg⁻¹, and 87.2 % retention after 5000 cycles, attributed to interlayer expansion and defect engineering. These findings demonstrate the effectiveness of transition metal incorporation in optimizing MoS₂-based electrodes for advanced supercapacitor systems.