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Title: Studies of stability and catalytic activity of lead dioxide electrodes
Author: Mohd, Yusairie
ISNI:       0000 0004 2693 2957
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2006
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The electrodeposition of stable and active, thick layers of pure and doped β;-lead dioxide (PbO₂) coatings from acidic nitrate baths onto gold and titanium substrates has been investigated. The morphology of the coatings has been analysed by Scanning Electron Microscopy (SEM) and the composition determined by Energy Dispersive X-ray Analysis (EDAX). In addition, the behaviour of the coated electrodes as anodes (using dimethylsulfoxide, DMSO, as a model substrate) and on open circuit has been defined. The structure and morphology of the β;-PbO₂ deposits on both Au and Ti substrates depend strongly on the deposition conditions including temperature, current density, deposition charge and the bath composition (Pb(II) concentration, H⁺ concentration, concentration and choice of dopant ions).  Satisfactory deposits on Ti require pre-etching of the Ti surface and very careful selection of the deposition conditions to avoid the presence of resistive TiO₂ layers. It was confirmed the activity of the β;-PbO₂ electrodes for the oxidation of organic compounds was significantly enhanced by the incorporation of bismuth. Bi-PbO₂ on Au was easily produced but on Ti it required a strategy involving the deposition of two layers. The procedures could be employed to produce uniform coatings on fine Ti meshes, a first stage in the design of three dimensional PbO₂ electrodes. The preferred coating on the Ti meshes was produced by the deposition of (a) an underlayer of Fe-F-PbO₂ onto etched Ti using 5 mA cm⁻² for 1800 s from 0.5 M Pb(NO₃)₂ M Pb(NO₃)₂ + 0.1 M HNO₃ + 0.04 M NaF + 10 mM Fe(NO₃)₃ (b) a top layer of Bi-PbO₂ using a low current density ~ 0.5 mA cm⁻² from 0.5 M Pb(NO₃)₂ + 1 M HNO₃ + 10 mM Bi(NO₃)₃. The coated Ti meshes were demonstrated to be suitable for the anodic decolouration of dyes (reactive blue 4, methyl orange, bromothymol blue and cresol red).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available