Nanocrystalline WO₃ thin films were prepared by spray pyrolysis technique onto heated glass substrates with different thickness by varying spray deposition time of the solution. The structural, surface morphology, microstructural, electrical properties and gas sensing performance of the WO₃ thin films were studied on exposure of various conventional gases. As prepared thin films were characterized by employing XRD, FE-SEM, TEM and EDAX to know crystal structure, surface morphology, microstructure properties and elemental composition respectively. The crystallographic structure of the films was studied by X-ray diffraction (XRD) with crystallite size found to be 16 nm. It is found that the films are hexagonal with (110) orientation. The film was observed to be most sensitive (S = 789) to H₂S at 50 °C. Furthermore, the H₂S sensor reported is cost-effective, user friendly and easy to fabricate. The quick response (6 s) and fast recovery (13 s) are the main features of this sensor.

Keywords: Nanocrystalline WO₃; Spray Pyrolysis; H₂S Gas Sensor;