Morphology effect of ceria supports on gold nanocluster catalyzed CO oxidation

The interfacial perimeter is generally viewed as the catalytically active site for a number of chemical reactions over oxide-supported nanogold catalysts. Here, well-defined CeO(2) nanocubes, nanorods and nanopolyhedra are chosen to accommodate atomically precise clusters (e.g. Au(25)(PET)(18)) to give different Au cluster–CeO(2) interfaces. TEM images show that Au particles of ∼1.3 nm are uniformly anchored on the ceria surface after annealing in air at 120 °C, which can rule out the size hierarchy of nanogold in CO oxidation studies. The gold nanoclusters are only immobilized on the CeO(2)(200) facet in Au(25)/CeO(2)-C, while they are selectively loaded on CeO(2)(002) and (111) in the Au(25)/CeO(2)-R and Au(25)/CeO(2)-P catalysts. X-ray photoelectron spectroscopy (XPS) and in situ infrared CO adsorption experiments clearly demonstrate that the gold species in the Au(25)/CeO(2) samples are similar and partially charged (Au(δ+), where 0 < δ < 1). It is observed that the catalytic activity decreases in the order of Au/CeO(2)-R ≈ Au/CeO(2)-P > Au/CeO(4)-C in the CO oxidation. And the apparent activation energy over Au(25)/CeO(2)-C (60.5 kJ mol(−1)) is calculated to be about two-fold of that over the Au(25)/CeO(2)-R (28.6 kJ mol(−1)) and Au(25)/CeO(2)-P (31.3 kJ mol(−1)) catalysts. It is mainly tailored by the adsorbed [O] species on the ceria surface, namely, Au(25)/CeO(2)(002) and Au(25)/CeO(2)(111) which were more active than the Au(25)/CeO(2)(200) system in the CO oxidation. These insights at the molecular level may provide guidelines for the design of new oxide-supported nanogold catalysts for aerobic oxidations.