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

Abstract

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.

The School for Science and Math at Vanderbilt: An Innovative Research-Based Program for High School Students

“…The goal is to expand access to this journal to all high school researchers at Vanderbilt and potentially establish Young Scientist as a national high school journal. Importantly, SSMV students have also coauthored publications in peer-reviewed scientific journals, with five publications to date ( Biswas et al. , 2012 ; Mandel et al.…”

Electrophoretic Fabrication of Robust Carbon Nanotube “Buckyfilms” for Flexible Electronics

“…The challenge of delaminating EPD buckyfilmshandled creatively in other publicationsactually did not pose a problem in the present work. , Although the MWCNTs presumably hydrogen bond with the rigid fluorine-doped tin oxide (FTO) layer at the substrate interface, as the initial deposit dries, the material contracts, and the internal tension in the film exerts a peeling stress at the MWCNT/substrate interface. While the minimum stress required to delaminate the MWCNT film is constant and fixed by the strength and density of the hydrogen bonding, the internal tension increases linearly with film thickness, and at ca.…”

“…Despite its promising capabilities, EPD has primarily been used to form extremely thin coatings of CNTs; ,− efforts to produce freestanding CNT films via EPD have resulted in films only several micrometers thick. , In contrast, the optimum electrode thickness for applications such as batteries and supercapacitors lies between 50 and 300 μm. , The development of appreciably thick freestanding films has been hindered by failure to examine the theory and mechanism of EPD in the context of CNT dispersions. Of particular exception is the comprehensive report published by Cho et al, which detailed the effects of dispersion concentration, time, and electric field strength for a particular MWCNT system .…”

Electrophoretic stabilization of freestanding pristine graphene foams with carbon nanotubes for enhanced optical and electrical response

“…1a,b) without the use of PMMA or other conventional polymer stabilization routes. Utilizing SWCNTs suspended in surfactantfree polar solvents [6][7][8], electrophoretic processing is scalable, inexpensive [9], capable of integration with manufacturing platforms, such as roll-to-roll or industrial systems [12][13][14], and overcomes the limitations of other SWCNT electrophoretic approaches which utilize surfactant [10,11]. We specifically observe stabilization of 3-D graphene foams that are found to maintain pristine optical response and significantly improved electrical response in comparison to PMMA-stabilized materials.…”