Rapid response and excellent recovery of a polyaniline/silicon carbide nanocomposite for cigarette smoke sensing with enhanced thermally stable DC electrical conductivity

In this paper, we present an electrical conductivity based rapid response cigarette smoke sensor with excellent recovery based on a polyaniline/silicon carbide (Pani/SiC) nanocomposite prepared by an in situ chemical oxidative polymerization technique in an acidic medium. The Pani/SiC nanocomposites and polyaniline (Pani) were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Results indicated that well ordered nanocomposites were successfully prepared. The morphology and electrical properties of the nanocomposites were influenced by the extent of loading of SiC nanoparticles. The as-prepared materials were studied for the change in their electrical conductivity on exposure to cigarette smoke followed by ambient air at room temperature. It was observed that the Pani/SiC-3 nanocomposite shows an eight times higher amplitude conductivity change than Pani on exposure to cigarette smoke followed by ambient air. The conductivity response in carbon dioxide, ammonia and methanol was also measured. It was observed that carbon dioxide (CO2) shows a low response while in the case of methanol and ammonia significant responses are observed, suggesting the possibility of a contribution from the above gases towards the response against cigarette smoke. Cigarette smoke also contains many other volatile chemicals such as polyaromatic hydrocarbons (PAHs), nicotine, hydrogen cyanide (HCN) and formaldehyde which may also interact with the polarons/bipolarons of polyaniline leading to a decrease in conductivity.