Gas sensing properties of chemically synthesized V₂O₅ thinfilms

Nanostructured vanadium pentoxide films have been synthesized by using a sol-gel technology from V₂O₅ powder and hydrogen peroxide. The V₂O₅ powder was dissolved in hydrogen peroxide solution, agitated and heated up to 65°C to form gel by the dissociation of the peroxide complexes. The obtained gel was deposited by dip coating technique and dried in air at room temperature. Structural, morphological and compositional analyses were carried out on the prepared samples using X-Ray Diffractometer (XRD), Raman spectrometer and scanning electron microscopy (SEM). The as-prepared films show an amorphous nature, while those annealed at 400°C exhibit orthorhombic structures. The films seem to have grain like structures on annealing which are expected to help the gas sensing properties of the V₂O₅ films. The annealed films were connected with copper electrodes and used as sensing element. The change in the resistance of the sensing element with respect to the test gas concentration was measured by noting down the resistance at each concentration. Sensitivity of the material linearly increased with different concentrations of ethanol and ammonia. It is clearly seen that the material has more sensing response for ethanol when compared to that of ammonia.