Room-Temperature Interaction of Nitrogen Dioxide with Rhodium Nanoparticles Supported on the Surface of Highly Oriented Pyrolytic Graphite (HOPG)

Samples of rhodium nanoparticles supported on the surface of highly oriented pyrolytic graphite (HOPG) are prepared by vacuum deposition; their interaction with nitrogen dioxide is studied by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). In the initial state, metallic rhodium particles with a size of about 2–5 nm are combined into aggregates localized on the steps and terraces, apparently, in the region of localization of structural defects. After treatment in NO2 at room temperature and pressures of 10−6 and 10−5 mbar, carbon oxidation accompanied by the degradation of the structure of 12–15 graphene layers on the HOPG surface is observed. Under these conditions, rhodium remains in the metallic state, and the Rh particles are encapsulated with carbon. The results are compared with data on the interaction of NO2 with Pt and Pd nanoparticles supported on the HOPG surface.