Mechanism of sonication-assisted electrophoretic deposition of carbon nano-fiber on carbon fabrics

Abstract

Uniform carbon nano-fiber (CNF) films have been deposited onto carbon fabrics by sonication-assisted Electrophoretic Deposition (EPD). To examine the effect of sonication, the distributions of voltage and pH values in the deposition bath were measured during EPD process. The degree of uniformity of CNF deposition was analyzed from the morphology of the deposited CNFs by scanning electron microscopy. The neutralization of negative charged CNFs by hydrogen ions, which were generated by electrolysis of water at the anode (carbon fabric), is essential for the adsorption of CNFs onto carbon fabrics. In addition, sonication increases the movement of ions in the suspension and accelerates the neutralization of CNFs at the anode. Moreover, sonication overcomes the aggregation and settlement of CNFs at the bottom of the deposition bath caused by gravity. The bubbles, which were generated by electrolysis of water, in the vicinity of the carbon fabrics were removed by sonication, resulting in the improvement of CNFs deposition. Based upon the results of voltage and pH values distributions during the EPD and analysis of morphologies of CNF films, a mechanism of sonication-assisted EPD has been proposed.