Electrochemical studies of diffusion in supercritical fluids

Abstract

The challenges and specialised equipment associated with supercritical electrochemistry means standard reference electrodes (such as the saturated calomel electrode) cannot be used. The aim of the thesis is the investigation of a range of metallocenes as model redox systems against a Pt pseudo reference electrode in supercritical fluids. This work was then extended to the development of a new high pressure reactor. Initially, a range of metallocenes were investigated in liquid analogues of the supercritical fluids (acetonitrile and dichloromethane) to investigate their suitability. Cyclic voltammetry performed at both micro and macro electrodes were used to examine the behaviour of each individual redox couple. Electrochemistry of the metallocenes were then evaluated in supercritical fluids (supercritical carbon dioxide with acetonitrile and supercritical difluoromethane) for investigation as model redox systems. The diffusion coefficients have been determined at both micro and macro electrodes for both supercritical fluids. The implementation of baffled micro and macro electrodes has shown that the intrinsic convection (at the electrode surface) within supercritical fluids can be dampened. The diffusion of metallocenes in nanoporous aluminium oxide membranes (13 – 55 nm diameter cylindrical pores), in both supercritical fluids has also been investigated. This work was then extended to the development of a new high pressure plastic reactor leading to the first, successful, supercritical fluid electrodeposition of bismuth in the plastic reactor.

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Identifiers

ORCID for Philip N. Bartlett: orcid.org/0000-0002-7300-6900

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