A Thermally Stable Cr–Cu Nanostructure Embedded in the CeO2 Surface as a Substitute for Platinum-Group Metal Catalysts

High catalytic activities for CO–O 2 and CO–NO reactions that were superior to or comparable with those of platinum-group metal catalysts were achieved by synchronous dual-mode arc plasma deposition of a very small amount of Cr and Cu (0.07 wt % each) onto CeO 2, followed by subsequent thermal aging at 900 °C for 25 h. The turnover frequency for CO oxidation over Cr–Cu/CeO 2 was 3-fold higher than that over Cu/CeO 2 and exceeded values for the Rh, Pd, and Pt catalysts loaded on CeO 2, despite a significant decrease in the surface area from 169 to 5 m 2 g –1 caused by thermal aging. Experimental structure characterization and density functional theory calculations based on CeO 2 (111) surface slab models revealed that Cu + substitution for surface Ce atoms leads to the formation of asymmetric 3-fold oxygen coordination sites capable of efficient CO chemisorption and catalytic activity. In addition, Cr 3+ was incorporated into the surface structure of CeO 2; it plays an important role in enhancing the surface concentration of Cu + . A CO oxidation rate with nearly zero partial orders with respect to O 2 and isotopic C 16 O– 18 O 2 reactions yielding C 16 O 2 as the primary product demonstrated that the reaction proceeds via the Mars–van Krevelen mechanism.