A stable iodine-doped multi-walled carbon nanotube-polypyrrole composite with improved electrical property

A highly conductive carbon nanotubes-polymer composite is fabricated by iodine doping. Interestingly, the conductivity of both multi-walled carbon nanotubes (MWCNTs) and polypyrrole (PPy) keeps unaffected by iodine, but the MWCNT-PPy composite shows ∼3.4 times higher conductivity only with 5 wt% of iodine doped the composite. The electrical property is proved to be stable at room temperature. Hall Effect tests reveals the increasing carrier concentration and mobility of doped MWCNT-PPy lead to the high conductivity. According to Raman and XPS investigation, PPy and MWCNTs form an extended conjugated system through π-π interactions, which favors the p-π interactions of iodine with MWCNT-PPy. As a result, a typical conductive carrier N+ in MWCNT-PPy composite raises significantly. Besides, the carrier mobility also increases due to the higher conjugate degree. Our results suggest that iodine doping is a useful way to improve the conductivity of as prepared CNTs-conjugated polymer products.