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Title: Mechanistic studies on semiconductor electrodes
Author: Dare-Edwards, M. P.
ISNI:       0000 0001 3404 6064
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1981
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A study has been undertaken of the detailed photoelectrochemistry of a number of III-V and oxide semiconductors. In particular, the work has been aimed at obtaining a material which can act as a stable and efficient photoelectrode for the solar photoelectrolysis of water. However to achieve this aim, it was considered essential to obtain a far deeper understanding of the mechanisms of the electrochemical reactions taking place at the semiconductor/electrolyte interface. The mechanism for Hydrogen evolution from the surfaces of the p-type III-V materials has represented a particular problem. P-type GaP was chosen as the representative member of the III-V materials and a mechanistic study has been made of the material using a.c. and d.c. experiments in addition to a detailed interfacial impedance analysis. A model for the Hydrogen evolution reaction has been proposed invoking surface bound Hydrogen atoms as both intermediates in the desired reaction and also as photogenerated surface states in parasitic recombination reactions. With the experience of the work on p-GaP, the analagous mechanisms to those found on p-GaP have been found to be consistent with results obtained on p-GaAs, p-InP and p-GaSb. However for these latter materials, additional complexities have arisen from their greater instability with respect to cathodic corrosion. A method has been sought for modifying the surface of the III-V materials in order to obtain improved Hydrogen evolution efficiencies. Such a modification has been discovered for p-GaP by the adsorption of a Ruthenium species from solutions of crude RuC13.xH20. Its mode of operation is discussed at length. For the oxide materials, a semiconducting oxide has been sought that possesses the ideal band energies and bandgap to obtain optimum photoefficiencies for the photoelectrclysis of water. The design constraints for such a material are presented and some results on a number of novel oxide semiconductors are discussed in relation to their use in such photoelectrolysis cells.
Supervisor: Goodenough, John B. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Electrochemistry ; Electrodes ; Semiconductors ; Solar energy ; Energy storage