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Studies of stability and catalytic activity of lead dioxide electrodes

Studies of stability and catalytic activity of lead dioxide electrodes
Studies of stability and catalytic activity of lead dioxide electrodes

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).

University of Southampton
Mohd, Yusairie
078945e0-ffc2-4eb0-898e-4b00d9644db7
Mohd, Yusairie
078945e0-ffc2-4eb0-898e-4b00d9644db7

Mohd, Yusairie (2006) Studies of stability and catalytic activity of lead dioxide electrodes. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

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).

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Published date: 2006

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Local EPrints ID: 466742
URI: http://eprints.soton.ac.uk/id/eprint/466742
PURE UUID: 344623d4-f2a8-45df-a5dc-fdf99406911d

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Date deposited: 05 Jul 2022 06:33
Last modified: 05 Jul 2022 06:33

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Author: Yusairie Mohd

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