Tailoring the nanoscale physicochemical properties of V2O5 thin films through Mn doping for enhanced electrochemical performance

Vanadium pentoxide (V 2 O 5 ) is a promising transition-metal oxide for energy storage and optoelectronic applications due to its layered crystal structure, multiple oxidation states, and high theoretical charge-storage capacity. In this study, pure and Mn-doped V 2 O 5 thin films were synthesized on ITO glass substrates using a cost-effective sol-gel spin-coating technique. X-ray diffraction confirmed the formation of a polycrystalline orthorhombic V 2 O 5 phase without secondary phases, indicating successful Mn incorporation into the host lattice. Mn doping modified the lattice parameters, crystallite size, strain, defect density, and surface morphology, confirming lattice distortion and defect-state formation. UV-visible spectroscopy revealed enhanced absorbance, reduced transmittance, and a narrowed optical response due to Mn-induced defect states and oxygen vacancies. Electrical measurements showed improved conductivity in Mn-doped films with near-linear current-voltage characteristics, indicating ohmic conduction. CV, GCD, and EIS were used to conduct the electrochemical investigations in a 5 M KOH electrolyte. The findings demonstrated that doping of Mn in V 2 O 5 greatly improved its electrochemical characteristics. Mn 4% doped V 2 O 5 thin film demonstrated the greatest electrochemical performance among all the prepared thin films, exhibiting superior specific capacitance and charge transfer kinetics. The findings suggest that Mn-doped V 2 O 5 thin films might be suitable for high-performance energy storage applications.