Characteristic dual-domain composite structure of reduced graphene oxide and its application to higher specific capacitance

Abstract

In this article, characteristic dual-domain structures of rGO layers, to be applied to fascinating electrode materials for energy storage systems, such as supercapacitors, are reported. Conductive atomic force microscopy (CAFM) technique reveals that the rGO surface consists of a dual-domain structure of graphene and GO components, which provide simultaneous electric-electrolyte pathways to the electrode, and that the amount, configuration, and connectivity of both domains are depend on the reduction level of rGO. The rGO sheet having a finely connected and well-balanced dual-domain composite structure provided higher specific capacitance compared to others. Using a concept of triple-phase boundary (TPB) where three phases, i.e., pseudo-type ceramic particle and the dual-domains coincide, hybrid composite sheets of Fe2O3@rGO and MnO2@rGO were also fabricated and examined for further enhancing specific capacitance. Besides, the reduction mechanism of the rGO layer by hydrazine to develop such dual-domain structures and the formation behavior of freestanding rGO sheets from rGO suspension were discussed in this study.