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Electrochemical oxidation of gold and thiourea in acidic thiourea solutions
Journal article   Peer reviewed

Electrochemical oxidation of gold and thiourea in acidic thiourea solutions

H-G Zhang, I.M. Ritchie and S.R. La Brooy
Journal of The Electrochemical Society, Vol.148(10), pp.D146-D153
2001
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Abstract

The dissolution of gold in acidic thiourea solutions, together with the oxidation of thioureu on gold, platinum, and glassy carbon (GC) electrodes, has been investigated using voltammetric methods. The cyclic voltammograms on platinum and GC electrodes showed a single pair of peaks for the oxidation of thiourea to formamidine disulfide and its subsequent reduction. The mechanism of the reaction is discussed. When a gold electrode was used, gold dissolution took place at a more negative potential than thiourea oxidation, with the latter reaction being shifted to a potential about 300 mV more positive than that on the platinum electrode. It was found that, at 25°C and without formamidine disulfide, gold did not dissolve when the potential was scanned rapidly. This result shows that the process of gold dissolution might include a slow surface step which can be accelerated by formamidine disulfide. It is possible that the slow surface step results from the strong adsorption of thiourea on the gold surface. The adsorption of thiourea on gold was demonstrated using the electrochemical quartz crystal microbalance.

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Citation topics
7 Engineering & Materials Science
7.229 Mineral & Metal Processing
7.229.774 Bioleaching
Web Of Science research areas
Electrochemistry
Materials Science, Coatings & Films
ESI research areas
Chemistry
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