Construction of hierarchical holey graphene/MnO2 composites as potential electrode materials for supercapacitors

Three-dimensional holey reduced graphene oxide/MnO2 composites, which possess in-plane pores-containing graphene sheets and three-dimensional interconnection porosity, are fabricated via multiple steps including preparation of solution processible holey graphene oxide, hydrothermal-induced self-assembly of holey graphene oxide to form three-dimensional holey reduced graphene oxide, and deposition of MnO2 onto holey reduced graphene oxide. By changing the immersion time of the holey reduced graphene oxide into the KMnO4 aqueous solution, a series of three-dimensional holey reduced graphene oxide/MnO2 composites are synthesized. Specially, the composite prepared with immersion time of 3 h presents remarkable performances for supercapacitor application, which exhibits a high specific capacitance of 192.2 F g(-1 )at a current density of 0.5 A g(-1) and a good capacitance retention of 79% after 5000 times of charge/discharge cycling at a current density of 1 A g(-1). The reasons for the enhanced electrochemical performance are investigated by various structural characterization and electrochemical measurement technologies. The results demonstrate that the unique porous structure, proper specific surface area, pore size distribution and electrical conductivity are ascribed to the good electrochemical performance of the prepared composite. The convenient preparation method and good electrochemical performance of this composite make it an attractive electrode material for supercapacitors. (C) 2018 Elsevier B.V. All rights reserved.