Effect of annealing temperature on the supercapacitor behaviour of β-V2O5 thin films

Abstract Vanadium pentoxide thin films are prepared via sol–gel spin coating method. The films coated on FTO and glass substrates are treated at different temperatures ranging from 250 °C to 400 °C. The structural, optical and electrochemical investigations are made. X-ray diffraction analysis shows the film to be composed of V2O5 in β-phase up to annealing temperature of 350 °C and at 400 °C the structural transformation to α-phase is observed. FTIR spectrum shows the formation of V O bond. The SEM images reveal the formation of nanopores. Optical absorption studies indicate a band gap of 2.2–2.4 eV. The supercapacitor behaviour is studied using cyclic voltammetery technique and electrochemical impedance analysis. The vanadium pentoxide films annealed at 300 °C for an hour exhibits a maximum specific capacitance of 346 F g−1 at a scan rate of 5 mV s−1.