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A series of Pt/Cr1.3Fe0.7O3 catalysts were tested for CO oxidation, and the activities are improved by the presence of H2O. Such improvement is more significant on the single atom 0.2Pt/Cr1.3Fe0.7O3 than on the 2Pt/Cr1.3Fe0.7O3 containing Pt nanoparticles, with turnover frequencies of 0.396 and 0.094 s−1 at 60 °C under 1% CO + 1% O2 + 10% CO2 + 10% H2O, respectively. In-situ diffuse reflectance infrared Fourier transform spectroscopic study on these catalysts suggests that the promoting effect of H2O is due to the facile reaction between adsorbed CO and surface hydroxyl groups via H2O dissociation. Kinetic investigation reveals that the 0.2Pt/Cr1.3Fe0.7O3 gives a higher intrinsic rate constant than the 2Pt/Cr1.3Fe0.7O3 (9.23 × 10−5 versus 4.50 × 10−5 mol g−1 s−1 at 60 °C) for the formation of formate intermediate due to its weaker CO adsorption strength, which explains the more significant H2O promotion on the single atom Pt catalyst.

High-surface area nanosized CuO–CeO 2 catalysts were prepared by a surfactant-templated method and tested for CO oxidation. The catalysts were characterized by XRD, TEM, N 2 sorption, H 2 -TPR, and CO-TPR. The surfactant method can be used for preparing CuO–CeO 2 mixed oxides with a crystallite size of about 5 nm. The highest BET surface area of the catalysts was 215 m 2 g −1 , achieved over a 3.3% CuO content catalyst. XRD results indicated that the absence of a CuO phase with 12 % CuO content may partially incorporate in the CeO 2 lattice to form Cu x Ce 1 − x O 2 − δ solid solution, whereas a higher CuO content causes the formation of bulk CuO. These high-surface area nanosized catalysts were found to be very active for CO oxidation reaction; the lowest T 90 was 80 °C, achieved over a 12.0% CuO content catalyst. In addition, the CuO–CeO 2 catalysts also show high catalytic activity for selective oxidation of CO in excess H 2 at relatively low temperature. H 2 -TPR results reveal three reduction peaks for these catalysts, which could be attributed to reduction of the highly dispersed CuO, the Cu 2+ in the CeO 2 lattice, and the bulk CuO. Removal of the finely dispersed CuO in the catalyst by acid treatment resulted in a decline in catalytic activity for CO oxidation, indicating that the finely dispersed CuO species are the active sites for the reaction.