Preparation of MnO2 nanostructures by controlled crystal growth and its pseudocapacitive properties

MnO2 nanostructures were synthesized via a controlled crystal growth method. The results showed that the feeding speed of the starting material affected the physical characterization of the product but did not affect its microcrystal structure. MnO2 nanostructures, composed of interleaving nanoplates, exhibited a mesoporous characteristic and the morphologies were clew-like. Cyclic voltammetry in a mild aqueous electrolyte showed that the charge-storage process was poorly related to double-layer charging processes and was mainly Faradaic. The linear relationship between the response current density and scan rate indicated that the adsorption of cations on the MnO2 surface was the controlling process in the Faradaic reaction. The MnO2 with a mean pore size of 10.6 nm had a high specific capacitance of 404.1 F g(-1) in 1 mol L-1 Na2SO4 solution at a 2 mV s(-1) scan rate and 2% capacitance loss after 800 cycles at a 10 mV s(-1) scan rate. The MnO2 with good electrochemical performance is a promising supercapacitor material. (C) 2012 Elsevier B.V. All rights reserved.