Thickness dependent supercapacitor behaviour of sol-gel spin coated nanostructured vanadium pentoxide thin films

Abstract

Vanadium pentoxide thin films of various thicknesses have been prepared by sol-gel spin coating method on glass and conducting substrates. X-ray diffraction analysis reveals crystalline nature for the 6–12 layered films (170–310 nm). The crystalline films indicate a preferential orientation of the crystallites along the (200) plane. FTIR studies of the V₂O₅ xerogel show the presence of V–O–V and V= O bond confirming the formation of V₂O_5. The scanning electron microscope images reveal formation of nanostructures in the 6–12 layered films. Optical absorption studies indicate a band gap of 2.2–2.5 eV. Pseudocapacitance behaviour of the V₂O₅ films was studied using cyclic voltammetric technique and impedance analysis. V₂O₅ films of thickness 202 nm (8 layers) exhibit a specific capacitance of 346 F/g at a scan rate of 5 mV/s.

Keywords:

• thin films
• sol-gel process
• cyclic voltammetry
• electrochemical impedance spectroscopy