Potassium Hydroxide Activated and Nitrogen Doped Graphene with Enhanced Supercapacitive Behavior

For the goal of synthesizing high performance supercapacitor electrode materials to meet the pressing requirements of energy storage, a facile hydrothermal method was employed to prepare nitrogen doped activated graphene (N-AG), two steps, i.e., KOH activating and following nitrogen doping were performed using a hydrothermal method. Continuously increased I-D / I-G ratios were observed in the Raman spectra after KOH activation and following N-doping processes, indicating increased defects due to the etching effect of KOH and introduced nitrogen defects on graphene sheet. Stacked graphene with damaged sheets on the surface was clearly seen in TEM image after the KOH etching. The successful dopant of N was demonstrated by XPS spectra and EDS mapping, confirming the effective hydrothermal N doping method. The N-AG exhibited largely enhanced capacitance (186.63 F/g) and cycling stability compared with that of nitrogen doped graphene (N-G, 50.88 F/g) and activated graphene (AG, 58.38 F/g) due to the combined positive effects of KOH activation and N-doping.