Room-temperature ammonia gas sensor based on Ni-doped MoO₃ thin film prepared by spray pyrolysis method

This report presents the study on the physical and gas sensing properties of the pure and Ni-doped MoO₃ thin film-based gas sensor. Various characterization techniques were employed to analyze the physical properties of the spray pyrolysis synthesized thin film materials. According to the structural XRD investigation, all the prepared thin films exhibit a monoclinic crystal structure of MoO₃ thin films. The 4% Ni-doped MoO₃ thin film possesses the largest crystal size of 73 nm. Further, with the increment in Ni dopants concentration in MoO₃ thin films, the lattice constant and cell volume rise with a decrement in strain value. The tiny rod-shaped protrusions with reticulated nano-fibrous mesh morphology observed for all the thin films. The UV–Vis and photoluminescence studies revealed lower transparency, lower bandgap, and increased defects. The gas sensing studies confirm that the fabricated 4% Ni-doped MoO₃ thin film gas sensor showed better response towards the NH₃ gas with a maximum gas response of 1440 with minimum response and recovery time of 70 and 10 s compared to other fabricated gas sensors. The selectivity and reproducibility studies also revealed that our fabricated 4% Ni-doped MoO₃ thin film gas sensor had superior qualities to other fabricated devices, which could be better suited for commercial applications.