The interaction of oxygen and hot gold. Part 2.—Electron-diffraction, X-ray and electrochemical studies

Abstract

The nature of gold surfaces, after heating in low pressures of oxygen, has been studied by several techniques. Effects due to impurities on the surface were observed ; there was no evidence of the presence of an oxide of gold. The results suggest that the impurities in the gold diffuse to the surface and form isolated, projecting, regions so that there is only partial coverage of the gold surface by impurities. Evidence is reported which suggests that the lack of agreement in the published work on the electrochemical behaviour of gold is due to impurity effects.

Water on Au sputtered films

“…Consistent with such inactivity, it is the only metal which does not form an oxide on heating in air or oxygen at least up to 900 1C. 1,2 Such properties are critical to the production of reliable, reproducible and repeatable interfaces capable of both disposable and multiple uses. Many commercial products now incorporate Au nanoparticles because such low activity inhibits bacterial and fungal growth -for example, Au nanoparticle films are thought to act as ideal barriers between skin and dental implants.…”

Surface Oxidation of Gold Electrodes

“…The oxidation of gold has not received as much attention as that of platinum and is not, at present, well characterized. A number of studies have been made using chronopotentiometry (1)(2)(3)(4)(5)(6)(7). Of particular interest is the work of Laitinen and Chao (1) who combined potentiostatic techniques with galvanostatic measurements and established the steady-state concentration of oxide as a function of potential.…”

“…Of particular interest is the work of Laitinen and Chao (1) who combined potentiostatic techniques with galvanostatic measurements and established the steady-state concentration of oxide as a function of potential. The final surface species is believed to be Au203 (perhaps hydrated) [e.g., (7)], but there is disagreement concerning the presence (5) or absence (1,4) of lower valent oxides. Although the surface coverage with oxidized species during galvanostatic oxidation has frequently been examined (2)(3)(4)(5)(6)(7)(8), apparently no attempt has been made to examine the kinetics of the reduction of the oxides of gold.…”

“…The final surface species is believed to be Au203 (perhaps hydrated) [e.g., (7)], but there is disagreement concerning the presence (5) or absence (1,4) of lower valent oxides. Although the surface coverage with oxidized species during galvanostatic oxidation has frequently been examined (2)(3)(4)(5)(6)(7)(8), apparently no attempt has been made to examine the kinetics of the reduction of the oxides of gold. In the present work, the kinetics of reduction of films formed potentiostatically have been studied over a range of pH.…”

ESCA Studies of Electrode Surfaces

“…X-ray and electron diffraction methods are valuable, but need thick and crystalline films (generally greater than ten monolayers thick). For example, even the thickest films that we have studied on a gold electrode by ESCA(I) are not seen by electron diffraction, (2) and in this case the films are appreciably decomposed by the electron beam. Mossbauer spectroscopy is a valuable method, but it is limited to certain elements, and again decomposition may occur.…”