PNNL

Abstract

The AT catalyst is significantly more active than the SEA catalyst at 50 °C. Ren and Chen[2] suggested that the difference in activity between the two catalysts might be related to a difference in metal dispersion. However, Supplementary Fig. 4 [1] shows that the mean particle sizes for the AT and SEA catalysts are 1.68 ± 0.3 and 1.58 ± 0.33 nm, respectively, confirming that the two catalysts in the original paper have a similar Pt dispersion.A similar particle size would also imply a similar interface area. Hence, the difference in reactivity arises from the nature of the ceria (different ceria redox properties at 50 °C, confirmed by NAP–XPS). The major difference between AT and SEA is the activation of the ceria support. In our recent publication[3], we further demonstrated that CO adsorbed on Pt in the AT sample reacts quickly at 70°C, if oxygen is available in interfacial sites. On the other hand, if the interfacial oxygen is depleted, CO is bound strongly. This proves unequivocally that the interfacial sites in the AT sample are necessary for low-temperature CO oxidation.