Carboxylic acid functionalized multi-walled carbon nanotube doped polyaniline for chloroform sensors

Polyaniline (PANI) nanocomposites doped with carboxylic acid functionalized multi-walled carbon nanotube (c-MWCNT) were synthesized by in situ chemical oxidation polymerization of aniline monomer using ammonium persulfate in the presence of c-MWCNT. Different techniques like Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscope, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to evaluate the interaction between PANI and c-MWCNTs as well as the nature of chain growth on the CNT surfaces. The response of the prepared PANI/c-MWCNT nanocomposite to different chlorinated methane vapor was examined and compared with that of the pure PANI. The nanocomposites showed better response to chloroform vapor as compared to pure PANI. The sensing performances of the formulated nanocomposites were compared in terms of their responses, response time and reproducibility for different vapor concentrations. It was found that the PANI/c-MWCNT nanocomposite sensors exhibited good selectivity toward chloroform vapor over the other chlorinated methane vapor. The nanocomposite containing 2 wt% c-MWCNT exhibited better sensing performance to chloroform detection. The UV–vis analysis was used to explain the sensing mechanism.