Interaction of Silver with a NO/O₂ Mixture:  A Combined X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy Study

Abstract

The treatment of a silver polycrystalline foil with a 1:100 NO/O 2 mixture at atmospheric pressure and room temperature led to the formation of a AgNO 3 /Ag 2 O/Ag “sandwich” in which no sharp boundary between the superimposed layers could be detected. The morphology of the as obtained structure was studied by means of X-ray photoelectron spectroscopy and scanning electron microscopy. The upper layer consisted of AgNO 3 crystals of average size between 0.1 and 0.4 μm. It is suggested that silver(I) oxide was the product of the oxidation of metallic silver, whereas AgNO 3 resulted from the subsequent reaction of Ag 2 O with NO 2 in the gas phase. The underlying Ag 2 O layer, which was characterized by a rough surface and a high porosity, could be characterized after uncovering it by selective dissolution of the AgNO 3 in water at room temperature.