▎ 摘　　要

Graphene nanosheets were prepared by reducing graphite oxide with hydrazine hydrate. The effects of reduction time on the structure and morphology of graphene nanosheets have been investigated. Their electrochemical performance in aqueous and organic electrolytes was also analyzed. With an increase of reduction time, the C and N contents of graphene nanosheets increased, while the specific surface areas and the specific capacitances decreased. Changes in reduction time produced a significant effect on the numbers as well as the types of oxygen and nitrogen functionalities. The graphene nanosheets, prepared by using a reduction time of 30 min have the highest specific capacitance of 192 F g(-1) in a 6 mol L-1 KOH electrolyte. All prepared graphene nanosheets have a good rate performance and cycle stability. (C) 2012 Elsevier Ltd. All rights reserved.