“…Regarding the support materials, the most widely used reducible support is ceria (CeO 2 ): the fascinating property of ceria which renders it useful for CO oxidation is its oxygen storage capacity (OSC), allowing ceria to release oxygen under reducing conditions and then reversibly take up oxygen under oxidizing conditions, thus making it more effective as compared to irreducible oxides (Al 2 O 3 , SiO 2 ). 11 For Pt supported on ceria (Pt/CeO 2 ) catalysts, CO oxidation reaction has been extensively investigated with respect to the relevant parameters such as size and/or morphology of Pt nanoparticles, 12,13 crystal orientation of CeO 2 support, 14,15 oxygen vacancy concentration at CeO 2 surface, 16 and lattice distortion caused by interaction of the Pt and CeO 2 . 17 Indeed, a rate determining step in CO oxidation reaction has been reported as the reaction of adsorbed CO with oxygen species at the interface between Pt and CeO 2 , not the CO adsorption or the oxygen replenishment at the interface, 13,18 and the corresponding slow reaction step can be affected by both (i) the desorption characteristic of CO on Pt and (ii) the reduction characteristic of O atom at the interface.…”