Effect of PTFE thickness on gas sensing properties of TiO2/Pd-Doped ZnO nanostructures

Abstract

A key challenge for modern nano-industry is to produce precise, cost-efficient, multipurpose nano-devices, as there are a lot of fields demanding progress. Thus, gas sensors are coming in a various spectra of characteristics based on different material combinations for specific tasks. In this paper, a sensor based on ZnO, TiO2, Pd nanoparticles and Polytetrafluoroethylene (PTFE) coating showed interesting results for hydrogen, 2-propanol and n-butanol detection. Different selectivity was achieved by varying the thickness of the PTFE layer. Thus initially, a 40 nm layer at operating temperature of 300 °C showed selectivity towards n-butanol and at 250 °C towards hydrogen gas. After 3 months, it maintained selectivity towards hydrogen gas at 250 °C and improved considerably selectivity towards 2-propanol at 300 °C. Similarly, a 100 nm PTFE layer yields selectivity towards 2-propanol at 300 °C and acetone at 350 °C, while after 3 months repeated measurements showed increased selectivity towards hydrogen at 300 °C and 2-propanol at operating temperature of 350 °C. The sensor reveals how variations in polymer coating thickness modulate gas selectivity through structural effects, while still proving by maintaining selectivity of both samples after a period of 3 months that these results can be reproduced. This paper offers new prospects of polymer thickness influence on both selectivity and sensitivity while offering methods of how to tune initial sensors towards a target analyte. Such sensors are necessary to research and produce for further improvements in biomedical applications to attain a certain threshold for non-invasive diagnosis.