Cu-doping for improved BiVO4 nanostructured supercapacitors: A structural and electrochemical study

This study examines the impact of Cu doping on the supercapacitive properties of BiVO 4 nanostructures. It reports Cu-BiVO 4 nanostructures with varying Cu contents, prepared by the hydrothermal method, and studies their morphology and physical, structural, and electrochemical properties. XRD analysis revealed that all samples consisted of pure monoclinic BiVO 4 , with no significant secondary phases detected. The FTIR spectra displayed shifts in the V-O and Bi-O vibrational modes, indicating Cu was incorporated into the host lattice. Results from UV-Vis analysis showed that doping Cu into BiVO 4 enhanced absorption in the green-to-visible light range and shifted the optical absorption edge toward longer wavelengths, suggesting that the band gap could be narrowed by Cu doping. SEM-EDX provided detailed information on the morphology and uniformity of elemental distribution in the synthesized nanostructures. Electrochemical analysis using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods confirmed a significant improvement in the supercapacitive performance of Cu-BiVO 4 . When the 10% Cu-BiVO 4 electrode was fabricated, it achieved a higher specific capacitance (Cs) of 90.5 F/g at a CV scan rate of 10 mV/s, which is significantly higher than that of the synthesized pristine material. BiVO 4 (34 F/g). This was supported by GCD measurements, which showed specific capacitances of 60 F/g at 0.5 mA/g for the 10% Cu-doped material, 47 F/g for the 5% Cu-doped material, and only 12.5 F/g for BiVO 4 . This work highlights the significant impact of well-controlled Cu doping on both the physical and electrochemical properties of BiVO 4 , making Cu-BiVO 4 highly promising for advanced energy storage systems, as demonstrated through a combined theoretical and experimental approach. • The nanostructure retained the pure monoclinic scheelite phase of BiVO 4 , showing that Cu was successfully incorporated into the host lattice without forming secondary phases. • Cu doping enhanced light absorption in the green to visible range and narrowed the band gap, making the material more efficient for light-driven applications. • The 10% Cu-BiVO 4 sample demonstrated a significantly higher specific capacitance (90.5 F/g) compared to pristine BiVO 4 (34 F/g), highlighting the positive impact of doping. • SEM-EDX analysis confirmed the uniformity of the synthesized nanostructures and the consistent distribution of elements. • This research proves that controlled Cu doping can substantially improve the electrochemical properties of BiVO 4 , making it a highly promising material for advanced energy storage systems.