Carbon monoxide gas sensing features of zinc oxide nanoneedles: practical selectivity and long-term stability

Zinc oxide (ZnO) as a highly sensitive metal oxide semiconductor is exerting a growing significant influence on the detection of hazardous gases such as carbon monoxide gas (CO). However, elevated operating temperature and humidity have been exhibited the bottleneck of CO detection at ambient conditions. Therefore, in the present work, one-dimensional ZnO nanoneedles (ZON) were synthesized by a simple hydrothermal method, and their resistance-type gas sensor was made and applied for the CO sensing features investigation at environmental conditions. The ZON characterization has exhibited a hexagonal wurtzite phase of the pure crystallized ZnO with porous architecture. The CO sensing properties of the ZON sensor (ZS) were studied in various gas concentrations and relative humidity (RH), to examine these main factors at room temperature. Our handmade sensor was exhibited an appropriate response, long-term stability for more than 4months, and it had good selectivity to CO concentration than that other gases. Moreover, the ZS showed a linear relationship between the response and not only the gas concentrations at various RHs but also the RH toward different gas concentrations, which is very important for the calibration and practical use. Finally, the CO sensing mechanism of the ZS at ambient conditions was discussed as well.