Gold -oxide

Goldoiyd, n. gold oxide, specif, auric oxide, gold (III) oxide, -ammoniak, n. fulminating gold, -salz, n. auric salt. gold(III) salt aurate. 

Gold oxidation starts at electrode potentials > -t-1200 mV vs. AI/AICI3, first at the steps between different terraces. At higher potentials pits are formed, rapidly resulting in complete disintegration of the substrate. 

Shi, H., Asahi, R. and Stampfl, C. (2007) Properties of the gold oxides AU2O3 and AU2O First-principles investigation. Physical Review B - Condensed Matter 75, 205125-1-205125-8. 

The reduction potentials are dependent upon ligation of the gold species. Stabilization of either gold oxidation state can occur with suitable ligand choice [8, 9] (CyS is cysteinato) ... 

Although the gold particle size has importance in systems, which do not contain reducible oxide, such as MgO [201], still the majority of data indicate that high activity is related to the gold/oxide interface. The importance of this experiment is further underlined by the fact that within a 4-10 nm range of Au particle size the system is active [183], but around the gold particle within a short distance the support must be defected in order to activate the reaction components. 

The electron interaction between nanosized gold particles and iron oxide support is only one factor which determines the properties of the gold/oxide system. For instance, in the Au/FeO,c/Si02/Si(l 0 0) model sample the depth profile (after successive Ar ion bombardment at a... 

The catalytic activity in the CO oxidation should significantly increase due to the gold/oxide interface around the perimeter of nanoparticles [147], therefore, we assumed that this is true regardless of the sequence of gold or FeO c deposition provided that iron oxide is amorphous. When iron oxide is deposited onto Au/Si02/ Si(l 0 0) we call it inverse interface . 

The resulting formamidine disulphide acts as a gold oxidant,60... 

GOLDOX [Gold oxidation] A process for improving the extraction of gold from its ores by injecting oxygen into the cyanide solution by the VITOX process. Developed by Afrox, a subsidiary of BOC, and now used widely in South Africa, Zimbabwe, Australia, Canada, and the United States. 

This type contains a variety of ores, including(a) gold-pyrite ores, (b) gold-copper ores, (c) gold-polymetallic ores and (d) gold oxide ore, usually upper zone of sulphide zones. The pyrite content of the ore varies from 3% to 90%. Other common waste minerals are quartz, aluminosilicates, dolomite etc. 

Long chain alkylmercaptans and disulfides readily self-assemble on gold surfaces to form compact organized monolayers in which the sulfur is chemisorbed to the gold and the hydrocarbon tail is extended away from the surface (1.-5). The mercaptan monolayers strongly inhibit gold oxidation in dilute sulfuric acid and also block diffusion of aqueous ions (e.g. Fe 2 3, Fe(CN) 63, ... 

Figure 18. Cyclic voltammograms on Au(III) in sulfuric acid solution. (A) In O.SmAf H2SO4 at lOmAf s", (B) in 50mM H2SO4 + O.lmAf Ag at 2mA/ s, and (C) in 0.5mA/ H2SO4 + 0.1 itiA/ Ag at 2 mV s. The dotted curve of (C) represents a cyclic voltam-mogram in the gold oxidation region. (From Ref. 19.)...

The nanostructured Au and AuPt catalysts were found to exhibit electrocatalytic activity for ORR reaction. The cyclic voltammetric (CV) curves at Au/C catalyst reveal an oxidation-reduction wave of gold oxide at +200 mV in the alkaline (0.5 M KOH) electrolyte but little redox current in the acidic (0.5 M H2SO4) electrolyte. Under saturated with O2, the appearance of the cathodic wave is observed at -190 mV in the alkaline electrolyte and at +50 mV in the acidic electrolyte. This finding indicates that the Au catalyst is active toward O2 reduction in both electrolytes. From the Levich plots of the limiting current vs. rotating speed data, one can derive the electron transfer number (w). We obtained n = 3.1 for ORR in 0.5 M KOH electrolyte, and 2.9 for ORR in 0.5 M H2SO4 electrolyte. The intermittent n-value between 2 and 4 indicates that the electrocatalytic ORR at the Au/Ccatalyst likely involved mixed 2e and 4e reduction processes. 

Tobacco, cultivar White Gold Oxidant Phygon XL (variable) Antioxidant 78 510... 

Gold can be etched effectively with C2CI2F4 76) or with CCIF3 (77), while CF4/O2 etching causes staining. The observed staining is believed to be gold oxides, whose formation is enhanced by the presence of atomic fluorine (77). 

Synonyms auric oxide gold trioxide gold oxide gold sesquioxide Physical Properties... 

A growth of a gold oxide on Au electrodes in aqueous H2SO4 and KOH solutions has been observed and investigated by many researchers (see, for instance, the reviews by Jerkiewicz [365] and Burke and Nugent [366]). 

According to the presented model of oxides formation on Au, the outer surface of the thick oxide film exposed to the solution is either AU2O3 or Au(OH)3. The type of oxide determines the surface electronic structure and electrocatalytic properties. Electrocatalytic properties of gold oxide-covered electrodes have been discussed by Burke and Nugent [366, 368]. 

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