Ultrasmall Metal-Doped CeO₂Nanoparticles for Low-Temperature CO Oxidation

Ultrasmall ceria (CeO2) and metal-doped CeO2 nanoparticles in the sub-3 nm size regime were synthesized via a facile, single-step, liquid-phase thermal decomposition reaction in a monosurfactant medium, which plays the role of a solvent and coordination molecule. The nanoparticles were characterized by a combination of techniques including powder X-Ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy, and their catalytic activity was tested for the CO oxidation reaction. The results show that all the materials are highly crystalline in the as-synthesized form and monodispersed with a near-spherical shape. N2 sorption studies and porosity analysis confirm that the prepared materials after thermal treatment at 450 °C possess a very high specific surface area, up to 240 m2 g-1, and additionally a hierarchical mesoporous structure. The CeO2 and doped-CeO2 particles demonstrate superior catalytic activity for the low-temperature CO oxidation. Among the different kinds of doping, the Cu-Co co-doped CeO2 nanoparticles are the most active for the CO oxidation (T50 ≈ 54 °C and Ea = 39.5 kJ mol-1) followed by the Cu and Sm-doped CeO2 ones.