The structure characteristic and electrochemical performance of graphene/polyaniline composites

•The redox state of polyaniline in composites before reduction was emeraldine salt.•The polyaniline in composites after hydrazine reduction was emeraldine base.•The polyaniline was doped into the conductive emeraldine salt in acid electrolyte.

In this paper, polyaniline–graphene (PANI–G) composites were obtained through in situ polymerization of aniline in a suspension of graphite oxide, followed by reduction of hydrazine. The structure characteristic of the composites was characterized by fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction and scanning electron microscopy. Electrochemical performance of the composites as electrode materials was studied by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The results showed that the redox state of PANI was emeraldine base in hydrazine treated composites and the PANI–G composites exhibited a layered structure with increasing graphene ratio in composites. The PANI–G composites had good electrochemical performance in acid electrolyte, indicating the emeraldine base form of PANI can be doped into the conductive emeraldine salt form. The specific capacitance of the PANI–G composites increased and charge-transfer resistance decreased with increasing graphene ratio in composites.