Improved Ion-Transfer Behavior and Capacitive Energy Storage Characteristics of SnO 2 Nanospacer-Incorporated Reduced Graphene Oxide Electrodes

Abstract

This report demonstrates the modification of reduced graphene oxide (RGO) nanosheets by decorating SnO 2 nanorod bundles and nanoparticles on the surface for effective use of the graphene as supercapacitor electrode materials. The shape- and density-controlled SnO 2 nanostructures were prepared through hydrothermal synthesis and acted as spacer materials to physically inhibit the overlapping of the RGO sheets; this is known as the restacking effect. When measuring the electrochemical properties, the electrode comprising RGO with SnO 2 nanorod bundles (RGO−SnO 2 −NR) revealed a higher capacitance, rate capability, and cyclic stability than the RGO electrode with SnO 2 nanoparticles (RGO−SnO 2 −NP) and the bare RGO electrode, indicating the effective role of the surface-implanted SnO 2 spacer during the electrode reactions of the double-layer capacitor. The electrochemical superiority of RGO−SnO 2 −NR could be explained by the fact that wedge-like SnO 2 nanorod bundles between the RGO sheets promote fast transfer and approach of electroactive species to form the electrochemical double layer at the electrode surface. Moreover, the improved mass transfer behavior of the RGO−SnO 2 composite electrodes and the role of the SnO 2 nanostructures were reasonably verified by various electrochemical analyses. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim