The activity and thermal stability of RhOx/CeO2 nanocomposites prepared by radio‐frequency plasma sputtering

The model RhOx/CeO2 systems were prepared by radio‐frequency (RF) plasma sputtering of Rh electrode in O2 or Ar/O2 atmosphere. Thermal stability of the systems and their reaction probability towards CO oxidation were studied by X‐ray photoelectron spectroscopy. It was shown that the small oxidized Rh nanoparticles on the CeO2 surface (RhOx/CeO2) obtained by RF sputtering in O2 have spectroscopic characteristics close to those of Rh3+ ions highly dispersed in ceria lattice. The RhOx/CeO2 system remains stable upon heating in vacuum at 450°C and shows reactivity towards CO oxidation at T > 200°C. RF sputtering in Ar/O2 atmosphere results in the formation of larger rhodium nanoparticles that are close to Rh2O3 oxide. The Rh2O3/CeO2 system demonstrates lower activity in CO oxidation and cannot be reduced at a temperature below 300°C.