Thermally stable and highly sensitive ethene gas sensor based on polythiophene/zirconium oxide nanocomposites

Abstract

The poor sensitivity, selectivity and high-temperature stability are still the challenging problems even today in the fabrication of highly efficient gas sensors. To attain the most excellent gas sensing behaviour, high surface area, good conductivity and large pore size are highly desirable, which has become difficult to achieve through conventional materials. To this end, herein we are reporting a conducting polymer-based nanocomposite material as a potential candidate for ethene gas sensor. In this study, we have synthesized polythiophene (PTh) and polythiophene/Zirconium oxide (PTh/ZrO2) nanocomposite of high surface area and very efficient conducting network that allows the quantitative adsorption and desorption of analyte gas. The as-prepared materials were characterized using FT-IR, XRD, SEM, TEM and TGA techniques. These materials were studied for comparative DC electrical conductivity retention under the isothermal and cyclic ageing conditions. The variation in their DC electrical conductivity on exposure to ethene gas followed by ambient air at room temperature was studied for the potential application as ethene sensor. The formulation, PTh/ZrO2-3 nanocomposite was found to be more stable in terms of DC electrical conductivity retention under accelerated ageing conditions. On exposure to ethene gas, PTh/ZrO2-3 nanocomposite exhibited higher conductivity amplitude, i.e. 19 times greater and faster adsorption and desorption towards ethene as compared to PTh. The faster response and reversibility may be accredited to the relatively high surface area of PTh/ZrO2-3 nanocomposite, availability of appropriate sensing networks and active sites. Also, PTh/ZrO2-3 nanocomposite was observed to be excellent in selectivity towards ethene than other volatile hydrocarbons tested. The sensing mechanism is elucidated on the grounds of involvement of polarons of polythiophene and d-orbitals of zirconium during adsorption and desorption of ethene gas.