Electrical Conductivity and Alcohol Sensing Studies on Polythiophene/Tin Oxide Nanocomposites

Abstract Conducting polymer-based sensors have short response time at room temperature besides their good electrical conductivity. However, the poor electrical conductivity retention at a higher temperature and the failing reproducibility of sensors based on conducting polymers are an area of concern. To this end, we are reporting the preparation of polythiophene (PTh) and polythiophene/Tin oxide (PTh/SnO2) nanocomposites by an in-situ chemical oxidative polymerisation. The as-prepared materials were characterized by FTIR, SEM, UV-vis absorbance spectroscopy, TEM and XRD techniques. PTh/SnO2-3 (PTh/SnO2 nanocomposite containing 15% SnO2 nanoparticles) showed the highest DC electrical conductivity (9.82 × 10-3 Scm-1) in addition to a maximal stability as a function of DC electrical conductivity retention under accelerated isothermal and cyclic ageing conditions. We utilized PTh/SnO2-3 to fabricate a novel pellet-shaped sensor for the selective detection of some of the higher alcohols such as butan-1-ol (1o alcohol), butan-2-ol (2o alcohol), and 2-methyl propanol (3o alcohol) at room temperature. PTh/SnO2-3 exhibited the highest response in terms of variation in DC electrical conductivity and maximal reproducibility for butan-1-ol. Finally, the sensing mechanism was explained by the adsorption-desorption process of alcohol vapours on the large surface area of the PTh/SnO2 nanocomposites where electronic interactions between lone pairs of electrons of alcohol molecules with polarons of PTh cause the change in DC electrical conductivity.