A Novel Design for Gas Sensor of Zinc Oxide Nanostructure Prepared by Hydrothermal Annealing Technique

Zinc oxide (ZnO) nanoparticles were prepared under different conditions using hydrothermal technique. The effect of reaction time on the size and shape of the nanoparticles was studied. It was evident that with the increase in the reaction time, the size of the granules shrank and the nanotubes were formed in the FESEM image, appeared as cubes and nano-spheres. The ZnO powder had polycrystalline structure with (۱۰۱) peaks in the diffraction spectrum, as indicated by the X-ray spectra. The UV spectrum showed variation in the band gap due to the different sizes of the nanoparticles. The properties of the zinc oxide for hydrogen sulfide (H۲S) gas were studied as a function of temperature and change in time under the optimal lab conditions. The sensitivity, response time, and recovery time were calculated with operating temperatures. The results showed that the sensitivity had higher increase with raising the operating temperature. The maximum sensitivity of the tested gas sensor at ۵۰ ppm of H۲S was about ۱۰۹۸ % at around ۲۰۰ °C for ۱ hour. It was found that the lowest response time was at ۱۰۰ °C for ۱ hour, and the response time was ۸ s.