Diameter-Controlled Synthesis and Capacitive Performance of Mesoporous Dual-Layer MnO2 Nanotubes

Mesoporous dual-layer MnO2 nanotubes assembled from well-aligned MnO2 nanosheets are synthesized via a facile and efficient sacrificial template method. To begin with, the self-standing carbon nanofibrous membranes are prepared via electrospinning and high-temperature carbonization, followed by an in situ redox reaction in KMnO4 solution to coat the carbon nanofiber (CNF) template with MnO2 nanosheets until the CNFs are consumed. The synthesized dual-layer MnO2 nanotubes are composed of an inner shell of packed MnO2, and an outer shell of mesoporous sheet-ike MnO2. Importantly, the dimensions of the MnO2 nanotubes can be easily controlled by tuning parameters including CNF diameter and redox reaction temperature. The MnO2 nanotube electrode thus prepared manifests excellent cycling stability with a specific capacitance of 231 Fg(-1) and an areal capacitance of 309 mFcm(-2) for supercapacitors. This approach opens up a new way for designing MnO2 nanostructures as promising electrode materials.