Post-Electrophoretic Deposition Electrochemical Separation (PEPDECS): Optimization of the Fabrication of Freestanding Carbon Nanotube Films

Abstract

Scalable fabrication of freestanding carbon nanotube films (buckypapers) is of notable interest in nanotechnology due to emerging, real world applications for these lightweight and flexible materials. Post-electrophoretic deposition electrochemical separation (PEPDECS), a recently developed method for the scalable production of buckypapers, involves the electrophoretic deposition (EPD) of charged carbon nanotubes onto a flat substrate in a parallel-plate capacitor configuration, followed by a reversal of the direction of the electric field to detach the film. This study explored the characteristics of the deposition and liberation of the delaminated film, such as the applied voltage and the electrode size, in search of the optimum conditions for high quality buckypaper fabrication. Bubble formation on the film, due to the electrolysis of the suspension, increased as a function of the current density. The time required to delaminate a film completely from its underlying substrate was higher at higher initial current densities. Additionally, only when the applied EPD voltage was ≥2.8 V was the integrity of the buckypaper sufficient for them to be handled. The mechanical properties of the resulting films were examined to quantify their integrity. These experiments demonstrate the dependency of successful film fabrication on variable conditions during the initial EPD and provide a means to control the properties of the final films.

Electrophoretic deposition of carbon nanotubes: recent progress and remaining challenges

“…However, the use of aqueous solvents introduces a potential problem of gas evolution at the electrodes due to water electrolysis at higher voltages. This hydrogen gas evolution at the cathode and oxygen gas evolution at the anode can damage the deposits due to bubble formation, as well as reducing Coulombic efficiency [33,[87][88][89][90][91]. To suppress water electrolysis during EPD, modulated electric field-related approaches are emerging, as discussed in the Alternating current EPD section.…”