Fabrication of Homogeneously Dispersed Nanoneedle Manganese Dioxide/Graphene Composite for High-Performance Electrode Use in Supercapacitor

Abstract

Two types of graphene/MnO2 composites were synthesized by different reaction procedures. R-GO/MnO 2 was synthesized as follows: first, nanoneedle MnO 2 was formed on the GO sheets using various functional groups (GO/MnO 2 ). In the second stage, GO/MnO 2 was reduced to graphene/MnO 2 (R-GO/MnO 2 ) via the dipping method. rGO/MnO 2 was synthesized using a different reaction order: first, graphene oxide was reduced to graphene and nanoneedle MnO 2 was formed on graphene sheets. Characterization indicated that the nanoneedle MnO 2 structures in the R-GO/MnO 2 composite were homogeneously dispersed on graphene sheets, whereas MnO 2 in the rGO/MnO 2 composite formed aggregates due to absence of functional groups. The R-GO/MnO 2 electrode exhibited a specific capacitance as high as 327.5 Fg -1 at 10 mVs -1 , which was higher than that of the rGO/MnO 2 electrode (229.9 Fg -1 ). It is anticipated that the formation of nanoneedle MnO 2 on the GO surface following the reduction procedure could be a promising fabrication method for supercapacitor electrodes.