On the Oxidation of Gold

Abstract

Communications to the Editor Yol. 65 that were not exposed to oxygen. Therefore, the soluble platinum(IV)-alumina complex postulated by McHenry, et al., does not exist under reforming conditions, i.e., after reduction with hydrogen. Upon intentional oxygen exposure of the reduced catalyst, considerable amounts of platinum appeared as the soluble form. Because soluble platinum was obtained in the absence of alumina and in the absence of chloride, there is no evidence for a specific soluble platinum complex. A possible alternative for the species dissolved by HE may be metal upon which oxygen is chemisorbed. Both hydrogen3 and carbon monoxide2 chemisorption studies on reduced catalysts have been interpreted to indicate that the platinum is a very highly dispersed form. Thus, a large fraction of the platinum atoms is on the surface and available for chemisorption of oxygen. These particles, because of their small size, have exceptionally high surface energies. The very low value for soluble platinum in Experiment 9 shows that the chemisorbed oxygen is removed readily by hydrogen at room temperature. This is consistent with recent work by Chon, Fisher and Aston,6 which showed by a calorimetric technique that chemisorbed oxygen (or hydrogen) on platinum can be quantitatively titrated at room temperature with hydrogen (or oxygen).

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.…”