Conductive polyaniline composite films from aqueous dispersion: Performance enhancement by multi-walled carbon nanotube

The intractable multi-walled carbon nanotube (MWNT) was dispersed in aqueous solutions of conductive polyaniline (cPANI) by externally doping of MWNT/polyaniline (PANI) employing an organic polymeric phosphate acid as the dopant. Free-standing composite films were obtained from the MWNT/cPANI aqueous dispersion after drying. In comparison with the cPANI, the conductivity of MWNT/cPANI composites showed a 2 order of magnitude increase with the maximum value 1.2 S cm−1, at the MWNT loading of 1.0 wt% because of the doping effect of MWNT on PANI. Under the strong π–π interactions between PANI and MWNT which were discussed by FT-IR and UV–vis analysis, the redox performance of the MWNT/cPANI composites was significantly modified compared with the pure cPANI. In addition, the capacitive behaviors of the MWNT/cPANI films varied with the difference of the MWNT loading due to the morphology variation resulted from the established interactions. The enhanced specific capacitance with the highest value of 371 F g−1 at a current loading of 0.5 A g−1 was obtained for the MWNT/cPANI films containing MWNT content of 1.0 wt%, as well as the better cyclability.