40 research outputs found

    Radio frequency SF6 plasma modified single-walled carbon nanotubes: Synchrotron spectroscopy and plasma characterisation studies

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    Single-Walled Carbon Nanotubes are fluorinated within a Radio-Frequency Plasma Reactor using SF6 as a source gas. To develop an understanding of how varying experimental parameters affect the plasma, and hence the resultant modification of the nanotubes, a Langmuir Probe has been employed to study the plasma system. Information about plasma densities, electron temperatures, and the plasma potential is presented and discussed. An interesting oscillatory behavior within the plasma has also been observed and studied

    Transition from single to multi-walled carbon nanotubes grown by inductively coupled plasma enhanced chemical vapor deposition

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    In this work a simple and up-scalable technique for creating arrays of high purity carbon nanotubes via plasma enhanced chemical vapor deposition is demonstrated. Inductively coupled plasma enhanced chemical vapor deposition was used with methane and argon mixtures to grow arrays in a repeatable and controllable way. Changing the growth conditions such as temperature and growth time led to a transition between single and multi-walled carbon nanotubes and was investigated. This transition from single to multi-walled carbon nanotubes is attributed to a decrease in catalytic activity with time due to amorphous carbon deposition combined with a higher susceptibility of single-walled nanotubes to plasma etching. Patterning of these arrays was achieved by physical masking during the iron catalyst deposition process. The low growth pressure of 100 mTorr and lack of reducing gas such as ammonia or hydrogen or alumina supporting layer further show this to be a simple yet versatile procedure. These arrays were then characterized using scanning electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was also observed that at high temperature (550 °C) single-walled nanotube growth was preferential while lower temperatures (450 °C) produced mainly multi-walled arrays

    Characterisation of Methane Plasma Treated Carbon Surfaces

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    Los Alamitos, US

    Single walled carbon nanotube array as working electrode for dye solar cells

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    A new working electrode for dye solar cells has been fabricated incorporating an array of dye sensitised single walled carbon nanotubes on an indium tin oxide coated glass substrate as a replacement for the titania used in conventional dye solar cells

    The Oscillatory Adsorption of Organosilane Films on Aluminium Oxide: Film Morphology using Auger Electron Spectromicroscopy

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    © 2019 Elsevier BV. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (January 2019) in accordance with the publisher’s archiving policyThe morphology of Propyltrimethoxysilane films during the oscillatory growth mechanism is shown using Auger Electron Spectromicroscopy. While the link between oligomerisation of silane molecules on the substrate and the oscillatory growth mechanism has been proposed previously, here for the first time we show the presence of silane film islands through Auger Electron Spectromicroscopy elemental mapping of the substrate. Monitoring the morphology of the film at key peaks and throughout along the oscillatory curve reveals the formation of a stable thin, homogenous film along with the presence of islands approximately 20μm in diameter, whose numbers vary collectively during the adsorption/desorption mechanism. The measurable oscillations in silane substrate coverage has been directly linked to the repeated adsorption and desorption of silane islands on the aluminium substrate. The consequence of this mechanism is such that Propyltrimethoxysilane films behave most like a monolayer during the early stages of film growth, prior to siloxane oligomerisation
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