This thesis presents experimental work with the primary aim of developing new approaches for the detection and characterisation of nanoparticles via electrochemical methods. The first chapter introduces the fundamental aspects of electrochemistry while the second chapter discusses the need for nanoparticle detection methods and the nonelectrochemical and electrochemical techniques that are currently used in the measurement of nanoparticles. A novel way to quantify silver nanoparticles in aqueous solution is proposed via nanoparticle-electrode impact experiments. In this technique a suitably potentiostatted electrode is immersed in a nanoparticle solution so as to bring about the oxidation or reduction of a single nanoparticle upon its collision with the electrode surface. This “direct” nanoparticle impact technique is then employed to detect laboratory synthesised silver nanoparticles in seawater. It is further shown that this method is capable of sizing silver nanoparticles contained in a commercially available cleaning product. Commercial silver nanoparticles are subsequently monitored via a sticking and stripping technique where homemade gold electrodes fabricated from CDs are immersed in a seawater sample spiked with nanoparticles prior to stripping voltammetry. The reduction of hydrogen peroxide on the surface of silver nanoparticles impacting upon an electrode is also examined. This “indirect” nanoparticle detection method is shown to provide an accurate route to nanoparticle sizing. A Fickian model is subsequently proposed to describe nanoparticle transport to the substrate electrode in both direct and indirect nanoparticle detection techniques. The importance of determining the proportion of nanoparticles which adhere to the electrode surface upon impact is highlighted and the sticking coefficient of a gold nanoparticle at a carbon surface determined. This technique to monitor nanoparticle sticking is optimised by chemical modification of the substrate electrode in order to achieve a “sticky” surface improving the rate of silver nanoparticle sticking. Finally, the nanoparticle collision method is shown to be applicable to C<sub>60</sub> nanoparticles where their detection and sizing is achieved in non-aqueous conditions. The methods developed in this thesis make a significant contribution to the promising application of electrochemical techniques in the detection and characterisation of single nanoparticles.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:640011 |
| Date | January 2014 |
| Creators | Stuart, Emma J. E. |
| Contributors | Compton, Richard G. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:64288a5a-d195-4147-93c8-6546e2d08ba2 |
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