Daviddi, Enrico (2020) Developments in scanning electrochemical cell microscopy for applications to multiphase systems. PhD thesis, University of Warwick.

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Abstract

Scanning Electrochemical Cell Microscopy (SECCM) has proven powerful for gaining electrochemical knowledge of microscopically structured surfaces, and this work is aimed at expanding the horizon of its application to complex multiphase systems, through new examined materials, electrochemical methods, experimental configurations and methods of data analysis. Firstly, SECCM is applied in the conventional voltammetric mode to a microscopically mixed polymer electrode blend consisting of conductive P3HT and insulating PMMA, revealing that P3HT is still able to exhibit relatively facile electron transfer kinetics when in the blend, contrary to macroscale electrochemistry results, which are mostly controlled by parasitic resistance. Then, a new, current controlled (chronopotentiometric) SECCM setup is developed and tested on model systems of increasing complexity, demonstrating stable and reproducible local electrochemistry with widespread applicability, e.g., to measure the “onset potential” in an electrocatalytic system at minimal driving force. Chronopotentiometric SECCM is then applied to the study of structure-dependent Cu corrosion in a novel triple-phase aqueous nanodroplet/oil/metal configuration, where a newly developed electrochemistry/crystallography correlation analysis is applied to visualise the trend in surface activity across the whole spectrum of orientations within a polycrystal. The high-index facets present a complex pattern of surface reactivity that cannot be simply interpreted as combination of the behaviour of the low-index grains. Using the same system, but applying the conventional voltammetric SECCM mode, two possible oil related effects and their intercorrelations are then explored: the effect of dissolved O2 and the effect of an oil-soluble corrosion inhibitor. A strongly grain dependent and unique action is observed on both the anodic and cathodic reactions that drive Cu corrosion, with the high flux of O2 across the three phase interface dramatically enhancing (anodic) electro-dissolution, as well as changing the apparent mechanism of corrosion inhibition. Overall this work opens up a wide range of new possibilities for SECCM in the study of complex multiphase systems, with relevant application in the fields of opto-electronics, energy transformation and corrosion.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry Q Science > QH Natural history
Library of Congress Subject Headings (LCSH):	Scanning electrochemical microscopy, Electrochemistry
Official Date:	December 2020
Dates:	Date Event December 2020 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Unwin, Patrick R.
Sponsors:	Lubrizol Corporation
Format of File:	pdf
Extent:	xlv, 286 leaves : illustrations
Language:	eng

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