Electrical conductivity of Polypyrrole and Polypyrrole/Multi-walled Carbon Nanotube Composites and their acetone gas-sensing properties

Abstract

In this study, polypyrrole (Ppy) and polypyrrole/multi-walled carbon nanotube (Ppy/MWCNT) composites were synthesized using a chemical oxidation polymerization process, with methyl orange acting as a surfactant. X-ray diffraction (XRD) confirmed the amorphous structure of the Ppy/MWCNT composites, while Raman spectroscopy provided insights into molecular interactions. Fourier transform infrared spectroscopy (FTIR) verified the presence of C–H and C–C bonds in the nanocomposites. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the cylindrical shape and chemical composition of the composite particles. The electrical conductivities of Ppy and Ppy/MWCNT(20wt%) nanocomposites were measured as 2.25 and 3.849 S/cm at 30 °C, and 4.77 and 6.49 S/cm at 100 °C, respectively. At an acetone concentration of 200 ppm, the Ppy/MWCNT (20 wt%) composite exhibited the highest sensitivity, with a response of 62.18% and a rapid response time of 50 s. The effects of humidity and selectivity on the nanocomposites were also investigated, showing that acetone had the highest selectivity over CO₂, hexane, and chloroform. These results underscore the potential of Ppy/MWCNT nanocomposites as effective materials for acetone gas detection, offering advantages such as lower operating temperatures and improved selectivity and sensing performance compared to pure Ppy.