Structural and electrochemical impact of Co-doping in BiVO4 nanostructured supercapacitors

Abstract

In this work, we studied the effect of Co-doping in BiVO₄ nanostructures for improved supercapacitor performance. A one-pot hydrothermal method was employed to synthesize Co-doped BiVO₄ nanostructures at varying dopant concentrations (5 % and 10 %) and to investigate their morphologies and structural characteristics using various analytical techniques. XRD patterns revealed the presence of monoclinic and tetragonal phases, resulting from the synergistic effects of Co-doping and percentage tuning during the synthesis process. FTIR spectra identified the metal oxygen vibrational modes. UV-Vis analysis revealed tunable optical band gaps, indicating improved electronic properties resulting from Co-doping. An electrochemical study, including cyclic voltammetry (CV) and Galvanostatic charge-discharge (GCD), of the BiVO₄ material revealed an impressive enhancement in supercapacitor performance following Co-doping. The 10 % Co-doped BiVO₄ electrode exhibited a specific capacitance (Cs) of 211.00 F/g under a 10 mV/s CV scan rate, which significantly outperformed that of the 5 % Co-doped (170.2 F/g) and undoped (34.00 F/g) counterparts. Although GCD investigations revealed that 5 % Co-doping yielded the longest discharge times at low current densities (∼70 s for 5 % Co compared to ∼47 s for 10 % Co at 0.5 mA/g), both doped samples significantly outperformed the undoped BiVO₄. The results show the significant impact of Co-doping on the structural and electrochemical properties of BiVO₄, establishing Co-doped BiVO₄ as an excellent candidate for energy storage devices.