Several nanosized catalysts Co3O4–CeO2 with varying compositions were synthesized by a surfactant-template method and further promoted by a small amount of Pd (0.5 wt%). These catalysts exhibit uniform mesoporous structure and high surface area (>100 m2 g−1). The Co3O4 crystallites in these catalysts are encapsulated by nanosized CeO2 with only a small fraction of Co ions exposing on the surface and strongly inter- acting with CeO2. Such structure maximizes the interaction between Co3O4 and CeO2 in three dimensions, resulting in unique redox properties. The introduction of Pd prominently enhances both the reduction and oxidation performance of the catalysts, due to hydrogen or oxygen spillover. These catalysts prepared by surfactant-template method exhibit excellent oxidation performance, especially the ones promoted with Pd, which show markedly enhanced CO oxidation activity even at room temperature. Based upon the results of structural properties, redox behaviors and in situ DRIFTS study, two different reaction pathways over Co3O4–CeO2 and Pd/Co3O4–CeO2 are proposed.

The origin of the electrochemical promotion of catalysis (EPOC) was investigated via oxygen temperature-programmed desorption (O2-TPD) from a polycrystalline Pt film interfaced with YSZ. TPD experiments were carried out under operating conditions similar to those used for catalytic activity measurements. This study has clearly shown that an anodic current generates the migration of ‘‘backspillover’’ ionic oxygen species from YSZ toward the Pt surface. These ionic species act as promoters and enable the formation of weakly adsorbed oxygen species coming from the gas phase which are more reactive and thus responsible for the activity enhancement. The effect of polarization is to carry or to remove the promoting ionic species on the Pt surface. Therefore, electrochemical promotion of catalysis can be considered as an electrically controlled metal support interaction, where the support is an O2- conducting solid electrolyte.

The complex oxide Ba–Fe–O catalysts were prepared by sol–gel method. The XRD, DTA, NO-TPD, XPS and NSC measurements were used to characterize the structures, NOx storage property and sulfur resistance ability. It is concluded that when coadsorption of NO and O2 at 400 C, the sample calcined at 750℃ possesses high NOx storage capacity and sulfur resistance. The perovskite type BaFeO3 and BaFeO3-x phases are the active centers in the catalyst for NOx storage.