Synthesis and characterization of spray deposited ZnO–CuO nano composite thin films for the detection of xylene

Xylene is a toxic, volatile organic compound that harms human health and needs an accurate sensing mechanism. Developing metal oxide semiconductor-based gas sensors for xylene detection is a crucial area of research to improve the quality of human life. In the present work, we report the synthesis of pure ZnO and ZnO–CuO composite thin films using a chemical spray pyrolysis approach with optimized deposition conditions. X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy studies were carried out to determine the micro-structural characteristics of the films. The XRD studies have displayed that the sprayed films were polycrystalline in nature with the Wurtzite phase. The crystallite size was determined with the Scherrer formula, showing an increase from 24 to 40 nm as the concentration of CuO was enhanced. Morphological studies were interpreted using field emission scanning electron microscopy (FESEM). The results demonstrate that the deposited thin films are composed of aggregated spherical particles with uniform distribution. Chemical oxidization states in the sprayed films were examined with XPS. Nano structural properties have been investigated using transmission electron microscopy. ZnO composite-based thin films offer great potential for gas-sensing applications due to their enhanced sensing performance, sensitivity, and cost-effectiveness. Gas-sensing properties of pristine ZnO and CuO-added ZnO thin films were investigated under ambient conditions in a static liquid distribution technique toward 5 ppm of xylene gas. The results show that the ZnO–CuO composite film with 15 wt% CuO responded well to xylene vapors with a good selective nature. Transient recovery and response times were also determined as 80 s and 42 s, respectively.