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Hydrothermal growth of ZnO nanowires were performed using ZnO nanoparticles as a seed layer. The growth was found to depend strongly on the reaction duration. These nanowires detected H2S with faster response and recovery time of 13 and 78 s, respectively towards 20 ppm at 350° C. The lowest detection limit was improved to 0.6 ppm upon annealing in O2 flow of 50 sccm. The response time was further improved to just 6 s towards 20 ppm of H2S at 350° C. The enhanced response characteristics have been attributed to the high surface area to volume ratio of nanowires. Photoluminescence (PL) studies showed increase in the green emission related to defect states in ZnO. This is also expected to contribute for the improved sensing characteristics. [ABSTRACT FROM AUTHOR]

The Kelvin Probe (KP) studies have been carried out on CuO:ZnO nanowires random networks before and after H2S exposure. The results show that on exposure to H2S, the work function of the CuO:ZnO NWs increases by 200 meV. Using conductance and KP data, both the components of work function i.e. band bending and electron affinity has been obtained. It was observed that the affinity values changed substantially with H2S gas exposure. [ABSTRACT FROM AUTHOR]