The electrochemistry of titanium oxide ceramic electrodes
The electrochemistry of titanium oxide ceramic electrodes
The electrochemistry of a conducting ceramic material marketed under the name Ebonex, and predominantly composed of the Magne*li phase titanium oxide Ti5O9 has been investigated. It is shown that this new electrode material exhibits a large potential range over both negative and positive potentials in aqueous electrolytes. Good stability and corrosion resistance is observed although, at positive potentials these properties are due to the irreversible formation of a passivating oxide layer. At negative potentials, the surface of the electrode undergoes reversible reduction and oxidation, although it is not possible to define the exact nature of this process. The electrodeposition of metals onto Ebonex ceramic cathodes has been studied. It is demonstrated that good quality coatings may be obtained and that the kinetics of the deposition and dissolution of the metals are similar at Ebonex to other common substrates. In addition, the kinetics of some simple redox couples at bare and coated Ebonex electrodes are compared; it is confirmed that such electron transfer reactions are very slow on the bare ceramic but when the surface is coated with a metal, the kinetics are similar to those on the bulk metal. The electrochemical generation of ozone and hydrogen peroxide have also been considered at bare and coated Ebonex anodes and cathodes respectively. For ozone generation, under the forcing conditions essential for its formation, Ebonex is not stable. In contrast, Ebonex electroplated with PbO2 is stable and gives current yields comparable to lead dioxide on other substrates in both acid and neutral electrolytes. The reduction of oxygen at Ebonex electrodes proceeds via two concurrent two electron reductions or via one four electron reduction. In either case, H2O2 is not a stable intermediate and Ebonex is not a suitable cathode for the electrochemical formation of H2O2 from O2. However, Ebonex electroplated with a thin layer of gold (1 μm) gives a current yield of 37%.
University of Southampton
1991
Graves, John Edward
(1991)
The electrochemistry of titanium oxide ceramic electrodes.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The electrochemistry of a conducting ceramic material marketed under the name Ebonex, and predominantly composed of the Magne*li phase titanium oxide Ti5O9 has been investigated. It is shown that this new electrode material exhibits a large potential range over both negative and positive potentials in aqueous electrolytes. Good stability and corrosion resistance is observed although, at positive potentials these properties are due to the irreversible formation of a passivating oxide layer. At negative potentials, the surface of the electrode undergoes reversible reduction and oxidation, although it is not possible to define the exact nature of this process. The electrodeposition of metals onto Ebonex ceramic cathodes has been studied. It is demonstrated that good quality coatings may be obtained and that the kinetics of the deposition and dissolution of the metals are similar at Ebonex to other common substrates. In addition, the kinetics of some simple redox couples at bare and coated Ebonex electrodes are compared; it is confirmed that such electron transfer reactions are very slow on the bare ceramic but when the surface is coated with a metal, the kinetics are similar to those on the bulk metal. The electrochemical generation of ozone and hydrogen peroxide have also been considered at bare and coated Ebonex anodes and cathodes respectively. For ozone generation, under the forcing conditions essential for its formation, Ebonex is not stable. In contrast, Ebonex electroplated with PbO2 is stable and gives current yields comparable to lead dioxide on other substrates in both acid and neutral electrolytes. The reduction of oxygen at Ebonex electrodes proceeds via two concurrent two electron reductions or via one four electron reduction. In either case, H2O2 is not a stable intermediate and Ebonex is not a suitable cathode for the electrochemical formation of H2O2 from O2. However, Ebonex electroplated with a thin layer of gold (1 μm) gives a current yield of 37%.
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Published date: 1991
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Local EPrints ID: 460580
URI: http://eprints.soton.ac.uk/id/eprint/460580
PURE UUID: fa86016d-38a2-44f8-b7ad-539903374293
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Date deposited: 04 Jul 2022 18:24
Last modified: 04 Jul 2022 18:24
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Author:
John Edward Graves
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