ESR STUDY OF THE CLUSTERING OF CU IONS ON THE CERIA SURFACE IN IMPREGNATED CUO/CEO2

In order to understand the interaction between CeO2 and metal ions deposited on its surface, ESR has been used to study a CuO/CeO2 sample subjected to different outgassing, reduction and calcination treatments. The results indicate that the formation of oxygen vacancies on the CeO2 surface aids the incorporation of Cu2+ ions to the support, some of these being located in specific positions in the oxide surface where Cu2+ dimers consisting of pairs of similar ions can be stabilized. By increasing the calcination temperature, a deeper chemical interaction is produced, with agglomeration of copper to give species with ferromagnetic-type behaviour; this is probably due to an enhancement of the ionic mobility in the ceria lattice.