Atomically dispersed cerium species in NM_xCe_1-xO₂/Al₂O₃ (NM = Rh, Ru) catalysts

NM_xCe_1-xO₂/Al₂O₃ (NM = Rh, Ru; 0 < x < 0.15) catalysts prepared by a microemulsion method contain, in addition to ceria nanoparticles, an atomically dispersed CeO_x species that may be detected by high-resolution HAADF-STEM imaging. The CeO_x species exist also in the samples subjected to high temperature treatment in oxidizing and reducing atmosphere, but their concentration increases rapidly after reduction above 700 °C. Generation of CeO_x groups and their spreading over the alumina surface explains the effect of amorphization of ceria particles observed by XRD method.