A facile template-free synthesis of α-MnO2 nanorods for supercapacitor

Manganese dioxide nanorods were synthesized by a facile method through simply refluxing the reaction mixture of KMnO4 and MnCl2 solution in the presence of K2Cr2O7. The products were characterized by X-ray powder diffraction and scanning electron microscopy. alpha-MnO2 nanorods with diameters of 50-100 nm and lengths of 0.5-2 mu m were formed depending on the amount of K2Cr2O7 together with the reflux time. The formation mechanism of the alpha-MnO2 nanorods was discussed in detail. The electrode performance of manganese dioxide for use as capacitor was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge. The alpha-MnO2 nanorods which were prepared with a mass ratio of K2Cr2O7 to KMnO4 of 1:10 exhibited good electrochemical performance, and a specific capacitance as high as 245 F g (1) was measured at a current density of 1 A g (1). (C) 2013 Elsevier B.V. All rights reserved.