Improving gas sensing performance of zinc-cobalt oxide nanostructured thin films by plasma jet treatment
摘要
Zinc oxide and zinc cobalt oxide nanostructured films, with a 1:1 atomic ratio, were deposited by spray pyrolysis for gas sensing. The effect of treatment by an atmospheric plasma jet on the structural, morphological, and electrical characteristics demonstrates significant modifications that influence gas sensing performance. X-ray diffraction analysis displays an improvement in crystallinity, with variations in crystallite size and lattice strain. FE-SEM images show enhanced surface roughness and increased porosity after plasma treatment. Hall effect measurements show increased charge carrier concentration after plasma treatment, improving electrical conductivity. The zinc cobalt oxide films exhibited higher sensitivity toward NO2 gas than pure zinc oxide, with further enhancement after plasma exposure. The gas sensitivity of the plasma-treated zinc cobalt oxide films peaked at an optimized working temperature of 200 °C, demonstrating a 1.6-fold increase compared to the untreated film. Additionally, the treated zinc cobalt oxide film exhibited a rapid response time of 26 s and a recovery time of 28 s at 20 ppm NO2 concentration. The improved plasma-treated zinc cobalt oxide makes it promising for high-performance gas sensors.