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Title: Growth and electrochemical characterisation of single-walled carbon nanotubes on single crystal quartz
Author: Rutkowska, Agnieszka
ISNI:       0000 0004 2694 865X
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2010
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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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry