Synthesizing MnO2nanosheets from graphene oxide templates for high performance pseudosupercapacitors

Abstract

A facile method to synthesize layered manganese oxide nanosheets was developed for the first time by using graphene oxide as a template. The in situ replacement of carbon atoms on the graphene oxide framework by edge-shared [MnO₆] octahedra provides a new methodology to synthesize graphene-based two-dimensional nanomaterials. The transformation of graphene oxide into δ-type MnO₂ nanosheets results in an especially high surface area (157 m² g⁻¹), which is the highest value amongst today's MnO₂ nanomaterials. Moreover, the MnO₂ nanosheets demonstrated prominent capacitance (∼1017 F g⁻¹ at a scan rate of 3 mV s⁻¹, and ∼1183 F g⁻¹ at a current density of 5 A g⁻¹) and remarkable rate capability (∼244 F g⁻¹ at a high scan rate of 50 mV s⁻¹ and ∼559 F g⁻¹ at a high current density of 25 A g⁻¹), indicating their promise in high energy and power density pseudosupercapacitors.