Abstract
The gas sensing properties of ZnO nanostructures synthesized at various reaction times are reported in this study. The response of ZnO nanostructures to H2, NH3, H2S and NO2 gases was investigated at different operating temperatures and gas concentrations. Surface morphology analyses showed that the geometry of the nanostructures transforms with the synthesis reaction time. Topography analyses demonstrated a surface roughness of approximately 68.25, 70.31, 74.75nm for the samples synthesized for 24, 48 and 72h, respectively. The dependence of the morphology on the H2, NH3, NO2 and H2S gas sensing performance was observed. The alteration of the nanostructures diameter/geometry demonstrated a change in both the magnitude and temperature of the maximum sensor response. The 72h ZnO sensing material revealed improved response and higher sensitivity and selectivity to H2S gas, while the 24h sensing material revealed enhanced response and selectivity to NO2 gas at 300°C. Moreover, the 72h sensing material exhibited a higher sensitivity of 144.22ppm−1 at 300°C. These findings disclosed that by varying the synthesis reaction time, the sensing properties, such as the response, sensitivity and selectivity of the ZnO nanostructures could be tuned.
Published Version
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