Tuning graphene surface chemistry to prepare graphene/polypyrrole supercapacitors with improved performance

► A series of surface functionalized graphene derived from G-O and doped with polypyrrole to systematically investigate their performance as supercapacitor electrodes. ► Surface chemistry of graphene is found to be of significant importance to PPy growth and PPy/graphene electrochemical performance. ► N doped graphene/polypyrrole (NG-PPy) electrode has superior performance as supercapacitor electrodes. ► Introduction of N doping to carbon material before the growth of polypyrrole is essential to achieve enhanced activity for supercapacitor application.