The progressive oxidation of small Rh metal particles supported on model SiO2 and TiO2 supports has been quantified using high resolution electron microscopy (HREM) and volumetric oxygen uptake. Volumetric O2 uptakes show that Rh particles, with diameters of 5-10 nm, oxidize faster when supported on TiO2 than on SiO2. HREM reveals the existence of a rhodium oxide phase with a lattice spacing of 0.29 nm that grows parallel to the Rh (111) planes on the silica-supported catalysts. The stoichiometry of the oxide formed at lower temperatures suggest that this intermediate phase may correspond to RhO. Oxidation at higher temperatures transforms the Rh oxide particles to polycrystalline Rh2O3.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics