Electrochemical Deposition of Metals: Gold Deposition Studies

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Date
1998-02
Authors
VEGUILLA, CHARLOTTE POULLET
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Abstract
The electrochemical deposition of gold has been studied due to its importance in the electroplating and electronics industries. In this investigation the potentials at which gold can be deposited onto gold and platinum electrodes were detennined by cyclic voltammetry. The experiments were performed for 50 ppm gold solutions in 0.5 M, 1.0 M, and 2.0 M KCl. The potential sweep for the platinum electrode was varied from 1.1 V to -0.9 V vs. AglAgCl. For the gold electrode the potential sweep was between 0.85 V and -1.3 V vs. Agi AgCI. The gold deposition studies by the electrochemical quartz crystal microbalance (EQCM) were performed under the range of potentials determined in the cyclic voltammetry studies. The potentiostatic deposition of gold on the platinum electrodes of a quartz crystal microbalance was done at -1.0 V, -0.5 V, -0.1 V, 0.1 V, 0.5 V, and 1.0 V vs. Agi AgCl. No deposition of gold was observed at 1.0 V vs. Agi AgCl. The deposition on the gold / quartz electrodes was performed at the same potentials as platinum, except at 1.0 V vs. AglAgCl. An increase in the amount of gold deposited was observed with the increase in electrolyte concentration. A few experiments were performed with 200 ppm gold solution in 1.0 M KCI, to obtain the relation between the amount of gold deposited and its initial concentration in the solution. The mass of gold deposited onto the electrodes of the quartz crystal microbalance was determined using the Sauerbrey equation and Faraday's law of electrolysis. Comparing the values obtained by both methods it can be concluded that the quartz crystal microbalance can be used to quantify the amount of gold deposited onto gold and platinwn electrodes at 0.1 V and 0.5 V vs. Agi AgCl. The same behavior was observed at high gold concentrations. Surface analysis and layer thickness estimates indicated that the deposition was not unifoml. Cyclic voltammetry studies were performed also with the EQCM technique. It was found that the electrodeposition process is reversible for the platinum / quartz electrode. but is irreversible for the gold / quartz electrode.
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Keywords
Electrochemical Deposition of Metals , Gold Deposition Studies
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