Synthesizing MnO ₂ nanosheets from graphene oxide templates for high performance pseudosupercapacitors

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.