Influence of Various CuO Nanoparticles Concentrations on Sensing Performance of ZnO Nanorods Arrays Grown Using Hydrothermal Method

This study outlines a technique for enhancing a metal oxide semiconductor gas sensor's sensitivity to nitrogen dioxide (NO2) gas. Using a sol-gel and spin-coating process, the gas sensor was constructed from hydrothermally generated ZnO nanorods (ZNRs) and decorated with different concentrations of CuO nanoparticles (NPs). Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction, and optical characteristics were used to examine the gas sensor's morphology, crystal structure, and UV-Vis absorption. The primary pattern's hexagonal structure was revealed by X-ray diffraction and FESEM images, which showed the rough surface of ZNRs/CuO NPs. NO₂ gas-sensing characteristics were examined at three different CuO NP concentrations: 20, 40, and 60 mg/L. The energy gap of ZNRs, ZNRs/20CuO NPs, ZNRs/40CuO NPs, and ZNRs/60CuO NPs had values of approximately 3.25, 3.25, 3.24, and 3.04, respectively. The findings showed that ZNRs decorated with CuO, compared to the non-decorated ZnO nanorods, enhanced their sensitivity to NO₂ gas. The highest sensitivity was at ZNRs/60CuO, reaching 140% at 150°C compared to ZNRs, ZNRs/20CuO, and ZNRs/40CuO samples.