Process dependent graphene-wrapped plate-like MnO2 nanospheres for high performance supercapacitor

Two kinds of MnO 2 /graphene nanocomposites (M1 and M2) were synthesized by two different reaction procedures. M1 was synthesized as follows: the plate-like MnO 2 /graphene nanocomposite was obtained by using hydrazine reduction of MnO 2 /graphene oxide. M2 was formed as follows: the plate-like MnO 2 nanospheres was synthesized on the graphene nanosheet which was reduced by hydrazine reduction of graphene oxide. The M1 have a good electrochemical performance and the average capacitance is as high as 250.6   F   g −1 at 1   A   g −1 in 1   mol   L −1 Na 2 SO 4 electrolyte, which is higher than that of the M2 (206.8   F   g −1 ).