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Title: Electrochemical processing of carbon nanotubes
Author: Tay, Hui Huang
ISNI:       0000 0004 7656 9164
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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Electrochemical methods are highly versatile and useful ways to process single-walled carbon nanotubes. Individualised carbon nanotube solutions can be obtained by reductive charging, using a simple three-electrode system, thereby eliminating the need for damaging ultrasonication, non-scalable ultracentrifugation or the use of undesired surfactants. The electrochemical dissolution methods were also useful towards the purification of carbon nanotube fibres, where unwanted amorphous carbon and shorter nanotubes selectively dissolved, hence leaving behind the preferred longer nanotubes. With a suitable electrolyte system, oxidative charging can be used to perform similar dissolutions, where nanotube cations were obtained. Nanocarbon anions and cations, obtained through these electrochemical charging methods, can be readily grafted with functional side-chains. Traditionally, the grafting of nanocarbon anions is performed by a two-step process of chemically-reducing the nanocarbon to a defined charge to carbon ratio, followed by the addition of grafting agents. In comparison, electrochemical charging methods are continuous and thereby offer clear advantage over the traditional chemical methods, where redox active agents may be depleted and require replenishment. The electrochemical grafting of redox-active ferrocene on nanotube has further allowed an accurate and non-destructive determination of grafting ratio with cyclic voltammetry, which is preferred over thermogravimetric methods that are prone to over-estimations. In another part of this work, pre-solubilized carbon nanotube ions were electrochemically deposited onto an electrode surface through selective ion discharge, thereby demonstrating the full versatility of electrochemical processing methods.
Supervisor: Shaffer, Milo S. P. Sponsor: National Research Foundation of Singapore (Energy Innovation Programme Office)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral