Kinetics of electrophoretic deposition of nano-Co 3 O 4 coating

Co 3 O 4 with a coating architecture is one of the most promising transition metal oxides because of its wide application in electrochromic device, sensors, heterogeneous catalysts, electrocatalyst, supercapacitors and photocatalyst. In this study, an environment-friendly and cost-effective route for fabricating Co 3 O 4 coating was successfully realized through the aqueous EPD (electrophoretic deposition) method with nitric acid as an additive. The EPD kinetics of Co 3 O 4 with different solid loadings in aqueous dispersion was investigated in detail. It was found that more nitric acid needed for the surface charging of more Co 3 O 4 nanoparticles would also significantly change the EPD condition, such as the electric current passing through the cell and the temperature of the suspension that would lead to a serious stability decrease in the EPD system. As a result, the increase in the deposition rate of the Co 3 O 4 coating would be much lower than that in the solid loading. We also suggested that this conclusion may be noteworthy for aqueous EPD of some other nanoparticle kinds.