Effect of pyrolysis temperature on structural, morphological and electrochemical properties of vanadium oxide thin films

• Samples synthesis is followed by new improved automatic spray pyrolysis technique at different pyrolysis temperature (473–773 K).
• Synthesized samples show polycrystalline nature with orthorhombic crystal structure.
• CV shows mixed capacitive behavior.
• Highest achieved value of the specific capacitance is 428.25 F/g in 1 M KCl.
• EIS shows the electrode exhibits the capacitive behavior at lower frequency range with 1.37 Ω internal resistance.

Thin films of vanadium oxides (V2O5) were deposited on stainless steel substrates (SS) by using new improved automatic spray pyrolysis technique (SPT). Deposition was carried out via aqueous route at different pyrolytic temperatures varied from 473 K–773 K by the interval of 50 K. Structural, morphological and electrochemical properties of the deposited films were studied using X-ray diffractometer (XRD), Scanning electron microscopy (SEM), Cyclic voltammetry (CV), Charge-discharge test (CD) and impedance spectroscopy. Deposited samples show rough, mud like and dense morphology with agglomeration of nano grains. Deposit exhibits orthorhombic crystal structure. Sample deposited at 673 K shows highest values of specific capacitance 428.25 F/g at 5 mV/s scan rate, specific energy 18.73 Wh/kg, specific power 18 kW/kg, and columbic efficiency 74.42% in 1 M aqueous KCl. Electrochemical impedance spectroscopy reveals capacitive behavior for the samples. Sample shows 1.37 Ω combined internal resistance when scanned in the frequency range 1 mHz–1 MHz.