Synthesis of sulfonated graphene/polyaniline composites with improved electroactivity

The sulfonation of graphene by coupling with the diazonium salts of sulfanilic (SA) acid and amino-4-hydroxy-2-naphthalenesulfonic (NSA) acid is studied. Coupling with the diazonium salt of NSA gives the highest degree of sulfonation. Composites of polyaniline (PANI) and sulfonated graphene (SG) are prepared by the polymerization of aniline in the presence of the SG. The materials have been characterized by Raman, Fourier transformed infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. These materials are electrochemically active at pHs close to physiological pH due to the doping of PANI with the sulfonic groups in SG trapped in the polymer. Furthermore, good conductivity values are obtained.