Room Temperature Interaction of NO2 with Palladium Nanoparticles Supported on a Nonactivated Surface of Highly Oriented Pyrolytic Graphite (HOPG)

A sample of palladium nanoparticles with an average size of ~5 nm on the surface of highly oriented pyrolytic graphite (HOPG) was prepared by vacuum deposition. With the use of X-ray photoelectron spectroscopy (XPS), it was found that the interaction of the resulting Pd/HOPG sample with nitrogen dioxide at room temperature and a pressure of 10 –6 mbar led to the oxidation of graphite. In this case, palladium particles retained their metallic state. A comparison with the behavior of a palladium sample supported onto HOPG activated by ion etching under similar conditions showed that structural defects on the graphite surface did not play a decisive role in the oxidation of graphene layers. A comparison with the results obtained upon the interaction of NO 2 with Pt nanoparticles supported on the HOPG surface was made.