Effect of multi-walled carbon nanotubes on DC electrical conductivity and acetone vapour sensing properties of polypyrrole

Abstract

• First time utilization of PPy/MWCNTs nanocomposite for acetone vapour sensing. • Effect of MWCNTs on thermal stability, electrical conductivity and acetone sensing performance of PPy. • Conductivity of PPy increased from 0.16 Scm −1 to 2.27 Scm −1 by incorporating MWCNTs. • Sensing performance in terms of sensing response, reversibility and long term stability. • PTh/MWCNTs sensor showed 7.44 times greater response than PPy sensor at 0.01 vol% acetone concentration. Polypyrrole (PPy) and polypyrrole/multi-walled carbon nanotubes nanocomposite (PPy/MWCNTs) were synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmittance electron microscopy (TEM) and thermogravimetric analysis (TGA). PPy and PPy/MWCNTs were converted into pellets which were used in conductivity and acetone sensing experiments. The initial electrical conductivity of PPy increased from 0.16 Scm −1 to 2.27 Scm −1 by loading of MWCNTs into PPy matrix. At the same time, PPy/MWCNTs showed excellent conductivity retention properties as compared to PPy under both the isothermal and cyclic ageing conditions. A comparative acetone vapour sensing studies were carried out on PPy and PPy/MWCNTs sensors at different acetone concentration, i.e., 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 vol%. The PPy/MWCNTs sensor offered much-improved acetone vapour sensing performance as compared to PPy in terms of sensing response, reversibility and long term stability. PPy/MWCNTs sensor exhibited 2.44, 2.82, 3.06, 3.28, 3.88, 5.0, 5.42, 6.02, 6.08 and 7.44 times greater% sensing response than PPy sensor at 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 vol% acetone concentration, respectively.