Rutkowska, Agnieszka (2010) Growth and electrochemical characterisation of single-walled carbon nanotubes on single crystal quartz. PhD thesis, University of Warwick.

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Abstract

Single walled carbon nanotubes (SWNTs) have unique structural and electronic
properties which drive their use in many different fields of modern technology.
In electrochemistry, SWNTs have been shown to have outstanding electrochemical
characteristic enabling their application in trace level electroanalysis amongst
other areas. The SWNT electrochemical activity has been described as originating
solely from sidewall structural defects, oxidised open ends and post-growth metal
nanoparticles (NPs). However, recent studies have demonstrated the electrochemical
activity of pristine and defect-free SWNTs, grown on insulating substrates using
catalysed chemical vapour deposition (cCVD) method, suggesting sidewalls support
electron transfer (ET). In this thesis cCVD is employed to grow SWNTs of different
geometrical arrangements on single crystal stable temperature (ST)-cut quartz substrates
for the development of novel nanoelectrodes (NEs) and optically transparent
electrodes (OTE). Majority of the work concentrates on cCVD and electrochemical
studies of horizontally aligned SWNTs on ST-cut quartz. The quality of SWNT
horizontal arrangement is shown to strongly depend on the crystallographic structure
of the ST-cut quartz substrate. Perfectly aligned SWNTs are utilised as (i)
one dimensional (1D) templates for electrodeposition of silver NPs, and (ii) NEs for
the fundamental assessment of SWNT electrochemical behaviour. Formation of uniform
silver nanowires (NWs) on most of the SWNTs is possible at high deposition
overpotentials and times. Uniformity of the NWs indicates high structural quality
of the horizontally aligned SWNTs. Nernstian behaviour of SWNT NEs for simple
outer-sphere redox couples is shown in localised voltammetric measurements with
microcapillaries, 25 - 50 μm in diameter serving as probes, filled with the redox
active electrolyte solution and the reference electrode (RE). For the first time measurements
at single SWNTs in the positive and negative potential window are performed,
revealing a strong dependence of SWNT electrochemical activity on SWNT
structural and electronic properties. Finally, careful tuning of the cCVD parameters
enables growth of interconnected SWNT networks on ST-cut quartz, with complete
surface coverage and no sign of alignment. These ultrathin mats are utilised as novel
OT disk ultramicroelectrodes (OT-UMEs) with complete transparency in the ultraviolet
and visible (UV-Vis) range, metallic behaviour and improved electrochemical
usability in comparison to conventional solid UMEs.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Nanotubes, Electrochemistry, Chemical vapor deposition, Quartz
Official Date:	June 2010
Dates:	Date Event June 2010 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Macpherson, Julie V. ; Unwin, Patrick R.
Extent:	xxxiii, 244 leaves : ill., charts
Language:	eng

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