Highly selective gas sensors from photo-activated ZnO/PANI thin films synthesized by mSILAR

•ZnO/PANI based gas, temperature and photo sensor.•Cost-effective microwave assisted successive ionic layer adsorption and reaction (mSILAR) technique was used to prepare ZnO.•The sensor showed good sensitivity and selectivity towards liquid petroleum gas. Zinc oxide (ZnO) nano-polycrystalline thin films has been prepared by cost-effective microwave assisted successive ionic layer adsorption and reaction (mSILAR) technique. ZnO/PANI prepared by in situ polymerization technique and thin films were fabricated using spin coating. X-ray Diffraction analysis confirms the presence of hexagonal wurtzite ZnO structure in the ZnO/PANI composite. The field emission scanning electron microscope revealed the porous nature of ZnO/PANI films with nanosized grains. We observed PANI intensively affected the structural and electrical properties of ZnO films. The examination of sensors was carried out in the liquefied petroleum gas (LPG) concentration range of 30 to 450ppm. It was noticed that ZnO/PANI nanocomposite film possesses excellent LPG sensing properties at a room temperature compared with other volatile organic compounds, at an applied voltage of 1.5V. The composite films also exhibited significant sensing response of ∼6.11×102 towards temperature and light with recovery and response time of ∼3.5min and 2.16min, respectively. Finally, the fabricated sensor showed good repeatability and sensitivity upon cyclic exposure to gas, light, and temperature. The ZnO/PANI nanocomposite film demonstrated overall sensing behavior in terms of sensor recovery time and response as well as repeatability.