Gas sensitivity of a composite of multi-walled carbon nanotubes and polypyrrole prepared by vapor phase polymerization

摘要

A composite of multi-walled carbon nanotubes (MWCNTs) and polypyrrole (Ppy) has been synthesized by vapor phase polymerization, and characterized by Fourier transformed infrared spectra, Raman spectra, thermal gravimetric analysis, X-ray diffraction study and scanning electron microscopy. Its gas sensitive characteristics towards NH_3 vapor were investigated at room temperature. It was found that the composite exhibited a higher sensitivity than both Ppy and MWCNTs separately. In addition, the response was reversible even when the concentration of NH_3 vapor was as high as 12,500 ppm, in contrast to the usually observed unrecoverable response of carbon nanotubes and their composite to low concentration NH_3 vapor at room temperature. The oxidizing agents and dopants used for preparation of the composite have a great effect on its gas sensitive characteristics, which is related to its morphology and contact with the electrode.