Electrochemical studies on gold electrodes in acidic solutions of thiourea containing gold (I) thiourea complex ions

Groenewald, T.

doi:10.1007/bf00625961

Cited by 64 publications

(37 citation statements)

References 6 publications

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“…Some larger organic compounds are known to selectively form an adsorbed protective layer on the metal surface during deposition and thereby suppress vertical growth and enhance the chance of obtaining smooth thin layers of the deposited metal [10]. A small molecule such as thiourea (TU) induces a similar enhanced quality of electrodeposited copper when utilized as an additive to the plating bath [8,9,[11][12][13]. The mechanism is, however, less straightforward and involves not only the expected formation of an adsorbed TU-metal layer, but also the influence of redox and complexation reactions [12,13].…”

Section: Introductionmentioning

confidence: 99%

“…A small molecule such as thiourea (TU) induces a similar enhanced quality of electrodeposited copper when utilized as an additive to the plating bath [8,9,[11][12][13]. The mechanism is, however, less straightforward and involves not only the expected formation of an adsorbed TU-metal layer, but also the influence of redox and complexation reactions [12,13]. Arvia and co-workers have explored such interactions between TU and a series of metals including copper [14,15], silver [16], and gold [17].…”

Section: Introductionmentioning

confidence: 99%

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An electrochemical quartz crystal microbalance study of the etching of gold surfaces in the presence of tetramethylthiourea

Larsen¹,

Johannsen²,

Gothelf³

2004

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An electrochemical quartz crystal microbalance study of the etching of gold surfaces in the presence of tetramethylthiourea

Larsen¹,

Johannsen²,

Gothelf³

2004

Journal of Colloid and Interface Science

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“…Hence, the gold electrode surface is positive in a potential range studied. Positively charged complex species [((NH 2 ) 2 C=S) 2 Au , which are formed by reaction (6) in a potential range of the first peak, should desorb according to reaction (7) and pass inside the electrical double layer, where they interact with (NH 2 ) 2 C=S molecules by reaction (8) Such a behavior of gold electrodes during the corrosion dissolution in acidic TCA solutions was attributed [1,2] to the adsorption of TCA molecules on gold and their hydrolysis to yield hydrosulfides and sulfides (AuHS -and Au 2 S), which results in the formation of adsorption layers on the gold surface.…”

Section: Resultsmentioning

confidence: 99%

“…Processing the data of [7] on the anodic dissolution of gold from a rotating disk electrode (300 rpm) in sulfuric acid solutions of TCA (0.001-0.1 TCA, 0.1 M H 2 SO 4 ) at 303 K gave the reaction order in TCA n = 1.69-1.74 (Fig. 2b, curve 3).…”

Section: Resultsmentioning

confidence: 99%

“…As seen, the i a vs. E curves have three peaks characterized by the current I P at a corresponding potential E P . Taking into account the data on electrode potentials of gold (I) in TCA solutions ( E Au(I)/Au = 0.380 [6] and E Au(I)/Au = 0.410 [7]), the first peak in VA curves corresponds to the following electrochemical and chemical reactions:…”

Section: Methodsmentioning

confidence: 99%

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Kinetic Parameters and Mechanism of Gold Electrooxidation in Thiocarbamide Solutions

2005

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Kinetics and mechanism of gold electrooxidation in sulfuric acid solutions of thiocarbamide ( TCA ) are studied by measuring voltammograms ( VA ) of gold and glassy carbon ( GC ) electrodes. In a potential ( E ) range from -0.2 to 1.2 V ( SCE ), VA of a gold electrode demonstrate three peaks. The first and the second peaks correspond to gold electrooxidation to [AuTCA ads ] + and [Au(TCA ads ) 3 ] 3+ ions at E of 0.152 and 0.554 V, while the third one corresponds to TCA electrooxidation. The electrooxidation of TCA on GC electrodes is characterized by two VA peaks at 0.983 and 1.437 V. The first peak corresponds to the formation of formamidine disulfide (FADS) ( k a1 = 6.40 × 10 -4 cm/s), while the second peak corresponds to TCA oxidation to sulfides and hydrosulfides ( k a2 = 7.78 × 10 -5 cm/s). The composition of adsorption layers formed at the Au electrode is analyzed by Auger spectroscopy. The introduction of sodium sulfide into TCA solutions eliminates the formation of adsorption layers and accelerates Au oxidation in such solutions. The rate constants of gold electrooxidation k a = 6.31 × 10 -3 cm/s and Au(I) electroreduction k c = 5.46 × 10 -4 cm/s in TCA solutions are estimated. Kinetic parameters (charge transfer coefficients, reactions orders in carbamide) are determined and the mechanisms of Au and TCA oxidation in sulfuric acid solutions are proposed.

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Determination of Ethylenethiourea (ETU) at Trace Levels in Water Samples by Cathodic Stripping Voltammetry

Carvalho¹,

Nascimento²,

Bohrer³

et al. 2004

Electroanalysis

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A stripping voltammetric method for the determination of ethylenethiourea in water samples is described based on its adsorptive deposition at the hanging mercury drop electrode (HMDE). In a borate buffer (pH 9.0) as supporting electrolyte, ETU is deposited at þ 100 mV (vs. Ag/AgCl) and stripped during the cathodic scan. The linear range for the measurements was from 2.0 to 100 mg L À1 , with a detection limit calculated as 1.4 mg L À1 after a deposition time of 300 s and a RSD of 1.9% (n ¼ 5) for 50 mg L À1 of ETU measured. The interferences of some organic compounds and metallic ions were tested. Recoveries between 93 and 110% were obtained using the standard addition method for spiked samples of natural and drinking waters. The method is rapid and applicable in the monitoring of ETU residues in water samples.

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Electrochemical studies on gold electrodes in acidic solutions of thiourea containing gold (I) thiourea complex ions

Cited by 64 publications

References 6 publications

An electrochemical quartz crystal microbalance study of the etching of gold surfaces in the presence of tetramethylthiourea

An electrochemical quartz crystal microbalance study of the etching of gold surfaces in the presence of tetramethylthiourea

Kinetic Parameters and Mechanism of Gold Electrooxidation in Thiocarbamide Solutions

Determination of Ethylenethiourea (ETU) at Trace Levels in Water Samples by Cathodic Stripping Voltammetry

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