Nickel Oxide Thin Film: Room Temperature Sensing Properties for Ammonia Gas

Abstract

The detection of ammonia gas is crucial in various industries due to its toxic and corrosive nature. Nickel Oxide (NiO) has emerged as a promising material for gas sensing applications owing to its unique properties. Thin films of NiO have been explored for their potential in detecting gases at various temperature. In this study, nickel oxide (NiO) thin films were deposited securely and efficiently using a convenient and affordable spin coating technique followed by annealing at 250⁰c. Characterization of the structural and optical properties of NiO thin films were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX) and ultraviolent (UV) – visible spectroscopy. The XRD patterns revealed that all the prepared samples exhibited a cubic structure which matched well with the joint committee on powder diffraction standards (CPDS) database. The scanning electron microscopy (SEM) images revealed a homogeneous surface morphology for the films. The prepared samples exhibited high transparency, as evident from the transmittance spectra, and the absorption spectra were used to calculate the optical energy band gap. The prepared samples were then tested for gas sensing applications using a static gas sensing setup to detect various fuel gases such as ammonia at different concentrations (ppm) at room temperature. The result showed that the NiO thin films exhibited good selectivity and high sensitivity towards ammonia. The time response characteristics of the fabricated sensor, including response and recovery times, we calculated and recorded.