XPS study of gold oxidation with nitrogen dioxide in model Au/C samples

The interaction of NO2 with model samples obtained by the gold sputter deposition onto the surface of highly oriented pyrolytic graphite (HOPG) has been studied by X-ray photoelectron spectroscopy (XPS). It has been shown that 3D metal particles characterized by an Au4f (7/2) binding energy (BE) of 84.0 eV form on the initial smooth graphite surface. During the sputter deposition onto the surface of HOPG preliminarily activated by means of ion etching, gold atoms chemically bound to the carbon atoms form in the area of surface defects. Such atoms are characterized by a positive shift of BE(Au4f (7/2)). It has been established that the 3D particles are resistant to the action of NO2 under the pressure XXXXXXXX mbar at room temperature. On the contrary, atomic gold oxidizes under these conditions into Au(III) complexes bound to the graphite surface. It is assumed that gold atoms on the support surface play the role of active sites of gold catalysts in oxidation reactions.