Synthesis of mesoporous polypyrrole nanowires/nanoparticles for ammonia gas sensing application

•Polypyrrole (PPy) nanoribbons and nanoparticles were grown by chemical method.•PPy nanoribbons and nanoparticles were tested for ammonia gas sensitivity.•Raman spectroscopic methods used for ammonia gas sensing for PPy samples to understand the gas sensing mechanism in polypyrrole.•Electrical and Raman sensing behavior is well correlated.

Nanostructured polypyrrole (PPy) has been synthesized in the presence of anionic azo dye {sodium 4-[4-(dimethyl-amino)-phenyldiazo] phenylsulfonate} (MO) and cationic surfactant {cetyltrimethyl ammonium bromide} (CTAB). The synthesis of the prepared PPy samples was confirmed by Fourier transform infrared spectroscopy and structural analysis was carried out using X-ray diffraction technique. Scanning electron microscopy and high resolution transmission electron microscopy investigations confirm the formation of nanostructured PPy. Both the samples have different shapes and dimensions. The sample prepared in the presence of MO has the higher doping level, bipolaron concentration and electrical conductivity (4 S cm−1) as compared to the sample prepared in the presence of CTAB (1.69 × 10−4 S cm−1). The prepared samples were tested for porosity through BET measurements. It has been found that the PPy nanowires (S1) have larger surface area (156,056.0 cm2/g) as compared PPy nanoparticles (S2) (11,259.0 cm2/g). Moreover, PPy nanowires have shown better gas sensitivity (∼6%) as compared to PPy nanoparticles (∼4%) and well corroborated with porosity, surface morphology, and the Raman investigations carried out under ammonia environment.