Freestanding Carbon Nanotube Films Fabricated by Post-Electrophoretic Deposition Electrochemical Separation

A novel technique of producing freestanding carbon nanotube films (buckypapers) using electrophoretic deposition (EPD) and post-EPD electrochemical separation (PEPDECS) is introduced. Multiwalled carbon nanotubes (CNTs) were deposited from an aqueous suspension onto stainless steel substrates using a direct current EPD procedure. Following drying and reinsertion of the electrodes into deionized water, a reversal in the direction of the current between the electrodes and an increase in the electric field facilitated an intact separation of the film from the substrate. The surface morphology was studied using scanning electron microscopy; surface groups on the CNTs on both sides of the buckypaper were identified using Fourier transform infrared spectroscopy. PEPDECS yielded films with no appreciable degradation of the surface morphology or film integrity and with mechanical properties similar to those of buckypapers produced using other assembly techniques. FTIR analysis revealed that the likely mechanism that facilitates PEPDECS for the CNTs involves the metal-catalyzed electrochemical reduction of double bonds present in surfactant molecules that coat the CNTs. This suggests the potential for wider applications involving CNT films as well as applications involving similar chemical systems.