Electrophoretic nanotechnology of ceramic films

Abstract

Electrophoretic deposition (EPD) method has been developed for the deposition of nanostructured MnO₂ films. Small organic molecules, such as 3,4-dihydroxybenzoic acid (DHB), 3,4-dihydroxyphenylacetic acid (DHP), 3,4-dihydroxyhydrocinnamic acid (DHC), 3,4,5-trihydroxybenzoic acid (THB), hydrocinnamic acid (HCA) and 3-(4-hydroxyphenyl)propionic acid (HPA), were investigated as dispersing agents. It was shown that DHB, DHP, DHC and THB molecules, containing adjacent OH groups bonded to the aromatic rings, provide efficient stabilisation of MnO₂ nanoparticles and enable EPD of MnO₂ films. The results obtained for the DHB, DHP, DHC and THB molecules with different numbers of OH groups and different lengths of hydrocarbon chains were analysed and compared with corresponding experimental data for HCA and HPA without adjacent OH groups. It was demonstrated that the adsorption mechanisms of DHB, DHP, DHC and THB on MnO₂ nanoparticles involved the interaction of adjacent OH groups of organic molecules with Mn ions on the particle surfaces and complexation. The deposits were studied by Fourier transform infrared spectroscopy and scanning electron microscopy. The deposition yield measurements showed that the amount of deposited material can be controlled by variation of dispersant concentration in the solutions and deposition time. The deposition mechanism and kinetics of deposition are discussed. The films prepared by EPD method are promising materials for application in electrochemical supercapacitors.