Effect of MWCNTs Incorporation Into Polypyrrole (PPy) on Ammonia Sensing at Room Temperature

We reported the gas sensing properties of nanocomposites of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) made with two incorporation techniques, i.e., ex situ and in situ polymerization. The pure PPy and PPy-MWCNT nanocomposites prepared by both techniques were characterized by field emission scanning electron microscopy (FESEM), Raman, and Fourier transform infrared spectroscopy (FTIR). The good dispersion was confirmed for the MWCNTs into PPy matrix prepared via in situ technique. Furthermore, the gas sensing measurements of pure PPy and ex situ synthesized PPy-MWCNT nanocomposite were carried out for the case of NH3 at room temperature, and they revealed a slight increase in response for PPy-MWCNT (1.5 wt%) sample. Then, different mass ratios of MWCNTs (0.5–3.5 mg) were incorporated into PPy matrix via in situ polymerization, and sensing toward NH3, $\text{H}_{{2}}$ , $\text{C}_{{2}}\text{H}_{{5}}$ OH, and CO2 was investigated. The in situ prepared PPy-MWCNT (2.5 mg) composite showed superior sensing with 1.33%–29.74% response for 5–200 ppm NH3, 47/111 s as response/recovery time, high selectivity, and good repeatability toward NH3.