High-efficiency super capacitors based on hetero-structured α-MnO₂ nanorods

Hetero-structured manganese dioxide nanorods with α phase (α-MnO₂) were prepared by a facile hydrothermal route at low temperature. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption measurements were used to characterize the prepared hetero-structured α-MnO₂ nanorods. Supercapacitive performance of the hetero-structured α-MnO₂ nanomaterials as active electrode material was evaluated by cyclic voltammetry (CV) in alkaline medium. The MnO₂ hetero-structure with 2 × 2 tunnels constructed from double chains of octahedral [MnO₆] structure yield a significantly high specific capacitance of 298 Fg^-1 at 5 mV s^-1 and demonstrated a superior long term cyclic stability, with specific capacitance retention about 94% after 1000 cycles. The superior supercapacitive performance of the hetero-structured α-MnO₂ electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.