Pretreatment Effect on Ceria‐Supported Gold Nanocatalysts for CO Oxidation: Importance of the Gold–Ceria Interaction

The encapsulated Au/CeO 2 hollow composite shows the effects of different pretreatment conditions on CO oxidation, showing complete conversion temperatures for CO in the order O 2 pretreatment ( T 100 =74 °C)>N 2 pretreatment ( T 100 =142 °C)>CO pretreatment ( T 100 =167 °C). Because of the good confinement provided by the uniform pores of as‐prepared CeO 2 , the size of deposited Au nanoparticles embedded in the pores of CeO 2 can be well controlled. Pretreated Au/CeO 2 catalysts have a good stability with no clear deactivation even after 70 h. A systematic characterization was performed by employing various techniques (XRD, H 2 temperature‐programmed reduction, scanning transmission electron microscopy with energy‐dispersive spectroscopy, Raman spectroscopy, X‐ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy) to understand the importance of the Au–CeO 2 interaction. This revealed that the O 2 pretreatment may result in (a) the migration of lattice oxygen atoms to the surface region and clearly increased number of oxygen vacancies in CeO 2 ; (b) the increase of Au−O x and Au−O x −Ce bond lengths; (c) the creation of electron holes in the CeO 2 substrate and electron deficiencies in Au nanoparticles as well as a strong Au–CeO 2 interaction; and (d) increased number of bicarbonates on the surface and Au δ + −CO bonds were produced during CO oxidation. All these features are responsible for an overall enhanced activity of CO oxidation and high durability of the Au/CeO 2 hollow composite.