Effect of Particle Size on the Corrosion Behaviour of Gold in the Presence of Chloride Impurities: An EFC-ICP-MS Potentiodynamic Study (original) (raw)
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RSC Advances, 2013
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The Journal of Physical Chemistry C, 2021
Electrochemical stability of a commercial Au/C catalyst in an acidic electrolyte has been investigated by an accelerated stress test (AST), which consisted of 10,000 voltammetric scans (1 V/s) in the potential range between 0.58 and 1.41 V RHE. Loss of Au electrochemical surface area (ESA) during the AST pointed out to the degradation of Au/C. Coupling of an electrochemical flow cell with ICP-MS showed that only a minor amount of gold is dissolved despite the substantial loss of gold ESA during the AST (∼35% of initial value remains at the end of the AST). According to the electrochemical mass spectrometry experiments, carbon corrosion occurs during the AST but to a minor extent. By using identical location scanning electron microscopy and identical location transmission electron microscopy, it was possible to discern that the dissolution of small Au particles (<5 nm) within the polydisperse Au/C sample is the main degradation mechanism. The mass of such particles gives only a minor contribution to the overall Au mass of the polydisperse sample while giving a major contribution to the overall ESA, which explains a significant loss of ESA and minor loss of mass during the AST. The addition of low amounts of chloride anions (10 −4 M) substantially promoted the degradation of gold nanoparticles. At an even higher concentration of chlorides (10 −2 M), the dissolution of gold was rather effective, which is useful from the recycling point of view when rapid leaching of gold is desirable.
Materials Today: Proceedings, 2020
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Geochimica et cosmochimica acta, 1995
The solubility of Au-Ag alloy (electrum) + AgC1 (chlorargyrite) was measured in aqueous HCI/NaC1 solutions at 300°C. Equilibrium between the two solid phases provided a convenient and highly effective f~ sensor. By varying the initial electrum composition (XAu = 0.3 to 1.0), total chloride concentration (0.1 to 5.0 molal), and pH (HC1/(NaC1 + HC1) = 0.003 to 1.0), it was possible to survey a wide range in oxidation state (log fo2 = -13.3 to -35.1 ). High metal solubilities were measured under these conditions (0.3 to >3000 ppm Au; 1280 to >40,000 ppm Ag). All evidence indicates that Au dissolved as an aurous ( + I) chloride complex at 300°C. This species subsequently disproportionated to a mixture of auric (+ III) species and metallic Au upon cooling to room temperature.
Journal of Colloid and Interface Science, 2001
The behavior of AuCl(4)(-) ions during the formation of aluminum hydroxide at pH 6 was examined. With an increase in NaCl concentration, the content of gold taken up by aluminum hydroxide decreased, suggesting that chloro-hydroxy complexes of Au(III) ion were taken up due to the formation of Al-O-Au bonds. It was found unexpectedly that the Au(III) ions taken up were spontaneously reduced to elemental gold without addition of a specific reducing reagent and then colloidal gold particles were formed. The mechanisms for the uptake of Au(III) ions by aluminum hydroxide and for their spontaneous reduction are discussed. Copyright 2001 Academic Press.
Nucleation and growth of Au and Au–Pd nanoparticles at the beginning of electrochemical deposition
Materials Letters, 2015
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Chemical Communications, 2012
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