Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238101
Title: An impedance study of flow-through porous electrodes
Author: Berlouis, Leonard Evariste André
ISNI:       0000 0001 3461 4615
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1981
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Abstract:
A low frequency impedance analysis has been carried out on two types of porous electrode, namely a porous reticulated nickel foam and a packed bed of copper spheres. The frequency dispersion of the impedance of both electrode systems was determined at the equilibrium potential as a function of the composition and the flow rate of the solution. The thesis reviews the theory and methodology of impedance measurements. The description of the electrochemical properties of porous electrodes is primarily developed in terms of one-dimensional dispersion and this leads to a transmission line model of the porous electrode used here. The experimental study was carried out using phase sensitive detection, the instrumental equipment being largely constructed in the laboratories here from good quality components and optimised for low frequency response. A preliminary study was made of the rotating disc electrode with the object of comparing two models of the interfacial impedance in terms of their effectiveness in dealing with the low frequency diffusional relaxation under convective flow. The characterisation of the nickel foam was carried out using the redox system Fe(CN)6-/Fe(CN)6~ in aqueous KOH. Several interesting features were noted, including the dependence on KOH concentration of the electron transfer rate constant and of the reversible potential of the redox couple, as well as the magnitude and dependence of the double layer capacity on the concentration of the redox species. The study of the gravitationally consolidated bed of copper spheres was made using aqueous solutions of copper sulphate in sulphuric acid. An explanation is advanced for the uncharacteristic dependence of the Warburg coefficient on the concentration of cupric ions. Flow rate studies showed that the effective diffusion layer thickness was best described and considered in terms of lamina flow pasta planar rather than a curved surface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.238101  DOI: Not available
Keywords: Chemistry, general
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