The study of some platinum and palladium electroplating baths
The study of some platinum and palladium electroplating baths
This thesis describes an investigation of the chemistry of palladium and platinum electroplating solutions and a study of the electrode reaction: M(II) → M (M = Pd or Pt). Spectroscopic techniques (infra-red, UV-visible and platinum NMR) were used to define the structure of the complexes present in solution. Cyclic voltammetry on a macroelectrode (stationary or rotating) or on a platinum microelectrode was combined with potential step and electroplating experiments to study the mechanism of the electrode reactions. The palladium baths were based on an amine palladium complex (Pd(NH_3)_2X_2 X = Cl, Br or NO_2). In all cases, the major species in solution is Pd(NH_3)PROB*LEM and the electrode reaction is straightforward, Pd(NH_3)PROB*LEM + 2e^- → Pd + 4NH3. The loss of current efficiency arises from the competing reactions, oxygen reduction, hydrogen evolution and hydrogen absorption. The relative importance of each reaction was determined as a function of potential. It is possible to find potentials where oxygen reduction is the only competing reaction. Increasing convection allows a substantial increase in plating rate. Only in the bromide bath was the palladium redissolved anodically; hence in this bath it would be possible to use a dissolving palladium anode. The platinum bath studied was based on a tetramine platinum(II) complex. A jump of 60% in current efficiency was noticed for the electroplating process over a 5 K range around T = 360 K. Platinum deposition from Pt(NH3)PROB*LEM was found not to be mass transport controlled. Chemical reactions, probably ligand substitutions, clearly occur before the electron transfer. The study of some other amine complexes (Pt(NH3)3(H2O)2+ and Pt(NH3)2H2O)PROB*LEM) suggested that the electroactive may be Pt(H2O)PROB*LEM.
University of Southampton
1991
Le Penven, Roselyne
(1991)
The study of some platinum and palladium electroplating baths.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis describes an investigation of the chemistry of palladium and platinum electroplating solutions and a study of the electrode reaction: M(II) → M (M = Pd or Pt). Spectroscopic techniques (infra-red, UV-visible and platinum NMR) were used to define the structure of the complexes present in solution. Cyclic voltammetry on a macroelectrode (stationary or rotating) or on a platinum microelectrode was combined with potential step and electroplating experiments to study the mechanism of the electrode reactions. The palladium baths were based on an amine palladium complex (Pd(NH_3)_2X_2 X = Cl, Br or NO_2). In all cases, the major species in solution is Pd(NH_3)PROB*LEM and the electrode reaction is straightforward, Pd(NH_3)PROB*LEM + 2e^- → Pd + 4NH3. The loss of current efficiency arises from the competing reactions, oxygen reduction, hydrogen evolution and hydrogen absorption. The relative importance of each reaction was determined as a function of potential. It is possible to find potentials where oxygen reduction is the only competing reaction. Increasing convection allows a substantial increase in plating rate. Only in the bromide bath was the palladium redissolved anodically; hence in this bath it would be possible to use a dissolving palladium anode. The platinum bath studied was based on a tetramine platinum(II) complex. A jump of 60% in current efficiency was noticed for the electroplating process over a 5 K range around T = 360 K. Platinum deposition from Pt(NH3)PROB*LEM was found not to be mass transport controlled. Chemical reactions, probably ligand substitutions, clearly occur before the electron transfer. The study of some other amine complexes (Pt(NH3)3(H2O)2+ and Pt(NH3)2H2O)PROB*LEM) suggested that the electroactive may be Pt(H2O)PROB*LEM.
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Published date: 1991
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Local EPrints ID: 460443
URI: http://eprints.soton.ac.uk/id/eprint/460443
PURE UUID: 9366318b-8c8d-4ddd-baa2-f6c88dedb278
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Date deposited: 04 Jul 2022 18:22
Last modified: 04 Jul 2022 18:22
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Author:
Roselyne Le Penven
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