Effect of vanadium pentoxide concentration in ZnO/V₂O₅ nanostructured composite thin films for toluene detection

ZnO/V₂O₅ nanocomposite thin films were synthesised by the spray pyrolysis technique with optimised deposition parameters by varying the concentration of vanadium pentoxide. The X-ray diffraction results showed that the ZnO/V₂O₅ nanocomposite thin films have a Wurtzite-type hexagonal ZnO structure. We attained crystal phases at all concentrations. These results indicated that the two crystal phases of pure zinc oxide and vanadium pentoxide exist together within the composite thin film matrix. The morphology was investigated with field emission scanning electron microscopy and transmission electron microscopy (TEM). The microstructures of the deposited thin films were confirmed by Raman spectroscopy. The optical characterizations of the prepared samples were investigated by using a UV-vis spectrophotometer. X-ray photoelectron spectroscopy (XPS) was carried out to confirm the oxidation states of the elements existing on the surface of the composite thin films. The gas-sensing properties of the composite thin films towards toluene gas were studied at the temperature of 27 °C. The sensing mechanism for toluene gas was reported; the response and recovery times were determined from the transient response curve and were found to be 24 s and 28 s, respectively, for the optimised composite film.