Borrill, Alexandra (2020) Electrochemical and spectro-electrochemical investigation of metal electrodeposition. PhD thesis, University of Warwick.

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Abstract

Metals and metal ions are of great importance to our health and environment as well as having a range of technological applications. Many metals and metal ions are toxic, some even at extremely low concentrations such as Hg, whilst others are required for biological function such as Fe and Cu. As metals in different forms are prevalent in our environment it is important to have cheap, fast and reliable methods of analysing them down to the ppb level. Electrochemistry is a powerful tool for analysis and fundamental investigations due to its flexibility, sensitivity and relatively low cost. Electrochemical methods can be easily coupled with other techniques such as spectroscopy or microscopy to add a new dimension to the analysis, such as with electrochemical x-ray fluorescence spectroscopy (EC-XRF). Here the metal is pre-concentrated on an electrode surface by electrodeposition and then chemically interrogated using XRF. Previous EC-XRF studies have suffered from cumbersome set-ups, preventing progress to commercially viable systems. In this thesis, the coupling of different mass transport systems to different more user-friendly set-ups is explored for both in situ and ex situ EC-XRF methodologies.

Metals, particularly transition metals, are especially interesting elements with potentially useful properties for electrocatalysis, but often present challenges for analysis. For example, Cu is used as an electrocatalyst for the CO2 reduction reaction (CO2RR) that produces feedstocks and fuels from the unwanted greenhouse gas, this is important technology for the future of the environment and sustainable chemistry. Cu catalysts are extremely well suited to this application as the materials are cheap and abundant, while favourable reductions in overpotential and improved product ratios have been observed. However, the mechanism is not fully understood, and the degradation of these catalysts leads to loss of activity. Understanding the electrodeposition and growth of Cu nanoparticles is important for their application to the CO2RR. Herein, the electrodeposition of Cu nanoparticles was investigated in different pH and electrolyte solutions. The ability to quickly and reproducibly grow Cu nanocube electrocatalysts in a single electrochemical step without the use of any additives other than standard electrochemical electrolytes was demonstrated. The growth mechanism and degradation of these structures during electrocatalysis was followed using Transmission Electron Microscopy (TEM) on Boron Doped Diamond (BDD) TEM electrodes, allowing multi-step experiments.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Transition metals -- Analysis, Metal ions -- Analysis, Electrocatalysis, Electroforming
Official Date:	November 2020
Dates:	Date Event November 2020 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Sponsors:	University of Warwick. Diamond Science Technology Centre
Format of File:	pdf
Extent:	xxii, 221 leaves : illustrations (some colour)
Language:	eng

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