Effect of synthesis method on electrochemical activities of V2O5 nanoparticles for supercapacitor application

Abstract

Vanadium pentoxide (V₂O₅) has attracted attention for supercapacitor applications due to its multifunctional properties. In this work, V₂O₅ nanoparticles were synthesized using hydrothermal, solution combustion and sol–gel methods. The structural and morphological analyses of the samples showed the effect of synthesis methods on the electrochemical and optical properties of the V₂O₅ electrode. The V₂O₅ synthesised through hydrothermal (V₂O₅-HT), solution combustion (V₂O₅-SC) and sol–gel (V₂O₅-SG) routes exhibited irregularly shaped nanosheets, agglomerated spherical-like particles and nanocube-like structure, respectively. The average crystallite sizes of the synthesized V₂O₅ nanoparticles were determined as 19.16, 18.77 and 20.48 nm for V₂O₅-HT, V₂O₅-SC and V₂O₅-SG, respectively. The optical bandgap energy of each sample was also calculated as 2.25, 2.3 and 1.9 eV for V₂O₅-HT, V₂O₅-SC and V₂O₅-SG, respectively. Cyclic voltammograms show the V₂O₅ electrodes’ pseudocapacitive properties in Na₂SO₄ electrolyte and faradic characteristics in KOH electrolyte. The impedance data can be fitted to a modified Randle equivalent circuit. The V₂O₅-HT, V₂O₅-SC and V₂O₅-SG electrodes respectively exhibit specific capacitances of 48.0, 16.3 and 49 F/g at 1 mV/s, and 93.1%, 100% and 108.4% of capacitance retention after 5000 cycles in 1 M Na₂SO₄ electrolyte. Our work provides a comparative study on V₂O₅-based electroactive materials synthesised using different methods. The results suggest that the V₂O₅ electrode needs integration with appropriate materials to be a potential electrode material for supercapacitor application.