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 μm 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 μm 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 F g−1 was observed for the 50 μm 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.