Electrophoretic deposition of manganese oxide nanofibers

Nanofibers of MnO2 have been prepared by a chemical precipitation method. Electrophoretic deposition (EPD) method has been developed for the deposition of the nanofibers on various conductive substrates of complex shape. As-prepared nanofibers and deposited films were studied by transmission and scanning electron microscopy, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, thermogravimetric and differential thermal analysis. Electron microscopy studies of the nanofibers showed a large aspect ratio with a length ranged from 0.1 to 1 mu m and a diameter of about 2-4 nm. The EPD yield was studied at various experimental conditions. Film thickness was varied in the range of 2-100 mu m by variation in deposition time and voltage. The method enabled the formation of porous nanostructured films for application in electrochemical supercapacitors. Cyclic voltammetry data for the films tested in the 0.1 M Na2SO4 solutions showed ideal capacitive behavior and high specific capacitance (SC) in the voltage window of 0-1.0 V versus standard calomel electrode (SCE). The highest SC of 412 Fg(-1) was observed for the 50 mu m cm(-2) sample at a scan rate of 2 mV s(-1). The SC decreased with increasing film thickness and scan rate. The films showed good cycling behavior with no loss in SC during 1000 cycles. Obtained results indicate that EPD is a Promising method for the fabrication of manganese oxide electrodes for electrochemical supercapacitors. (C) 2008 Elsevier B.V. All rights reserved.