Electrochemical and Structural Characterization of Electropolymerized Composite of NH2-Graphene and Polyaniline

The NH
2
-graphene/polyaniline composites are synthesized by in situ electropolymerization of aniline monomer and NH
2
-functionalized graphene (“NH
2
-graphene”) sheets in acidic electrolyte solution by constant-potential coulometry. Cyclic voltammetry and FTIR analyses confirm the covalent attachment of polyaniline backbone onto NH
2
-graphene in the composite. Having the same functional moieties (NH
2
-group), the polyaniline nanofibers are grafted laterally forming ’synapses’ resulting in improved charge-transfer reaction and stability of the composite. This link is believed to be ’phenazine-like’ microstructure formed at the edges of graphene sheets as evidenced by SEM and TEM images. The voltammograms of the NH
2
-graphene/polyaniline composite films coated onto pencil lead graphite electrodes (PLGE) exhibit remarkable increase in the current density relative to the bare PLGE and polyaniline-coated PLGEs. Based on the electrochemical impedance spectroscopy (EIS) measurements, the enhancement in the electrochemical properties of the composite may be due to the good chargetransfer redox activity of polyaniline fibers that are grafted onto the NH
2
-graphene sheet. The composite film also demonstrated photo-responsive property which could be useful for sensing or photovoltaic cell design.