Manganese Oxide Nanorod with 2 × 4 Tunnel Structure: Synthesis and Electrochemical Properties

By means of a surfactant-assisted hydrothermal method, we have successfully synthesized sodium manganese oxide nanorods with 2 × 4 tunnel structure using layered manganese oxide as starting material. The nanorods have diameters of ca. 20 nm and lengths up to 1 μm. Not only the morphological change of manganese oxide from particle to rod but also the structural change from layer to tunnel have simultaneously been achieved during the hydrothermal treatment. The specific capacitance of thus obtained nanorods reaches to 140 F/g. About 57% of the capacitance at 1 mV/s could be maintained when the scan rate was increased to 100 mV/s.