Capacitance behavior of composites for supercapacitor applications prepared with different durations of graphene/nanoneedle MnO_2 reduction

摘要

Graphene/MnO_2 composites were prepared by hydrazine hydrate-mediated reduction of graphene oxide (GO)/MnO_2 at various reduction times to determine the optimal conditions for obtaining materials with excellent electrochemical performance. Variations in the oxygen-containing surface functional groups were observed as the reduction time was varied. These changes were found to affect the electrical conductivity and density of nanoneedle MnO_2, which influence the surface area and significantly affect the supercapacitive performance of the composites. Morphological and microstructural characterizations of the as-prepared composites demonstrated that MnO_2 was successfully formed on the GO surface and indicated the efficacy of hydrazine hydrate as a reducing agent for GO. The capacitive properties of the graphene/MnO_2 electrodes prepared at a reduction time of 28 h (rGO(28)/MnO_2) exhibited a low sheet-resistance value as well as a high surface area, resulting in a GO/MnO_2 composite with excellent electrochemical performance (371.74 Fg~(-1) at a scan rate of 10mV s~(-1)). It is anticipated that the formation of MnO_2-based nanoneedles on GO surfaces by the demonstrated 28-h hydrazine-reduction protocol is a promising method for supercapacitor electrode fabrication.