Publication

Abstract : The demand for the sensing of benzene vapor increases in recent times as its exposure to even 1 ppm concentration for 8 h leads to adverse health effects. Towards this, for the first time, we are reporting the room temperature benzene sensing properties of nanostructured ZnO–CdO mixed oxide thin films deposited using the spray pyrolysis technique. Three different ratios of ZnCl2 and CdCl2 (0.08:0.02 M), (0.06:0.04 M) and (0.04:0.06 M) were considered for the deposition of ZnO–CdO mixed oxide thin films. For the comparative analysis, pure ZnO thin film was also deposited and investigated. XRD pattern divulged the growth of cubic phased CdO and hexagonal wurtzite phased ZnO for the mixed oxide thin films deposited in the three different ratios. Surface morphologies revealed the formation of spherical nanograins for the pure ZnO thin film, whereas it started to aggregated randomly for the films deposited in the ratio of (0.08 M:0.02 M) and (0.06 M:0.04 M). In contrast, the mixed oxide thin film deposited in the ratio of (0.04 M:0.06 M) showed nanoflakes-like morphology. The pure ZnO thin film was selective towards ammonia vapor, whereas all the mixed oxide thin films were selective towards benzene vapor. In particular, the film deposited in the ratio of (0.04 M:0.06 M) showed a selective response of 453 towards 100 ppm of benzene with a response and recovery times of 57 and 65 s respectively at room temperature (48%RH). The detection range was found to be 1–200 ppm of benzene. The influence of grain boundary effect on the sensing response was also studied and reported.