Role of the FeOx support in constructing high-performance Pt/FeOx catalysts for low-temperature CO oxidation

Based on a simple colloid deposition method, a series of Pt/FeOx catalysts were prepared using 3–4 nm Pt colloid nanoparticles and FeOx with different microstructures (i.e. the structure and surface properties). The FeOx support was obtained via a thermal treatment method, which enables the tailoring of FeOx from ferrihydrite to α-Fe2O3, and the amount of hydroxides on the surface of FeOx decreases gradually with the phase change. Over optimized Pt/FeOx, CO could be completely converted at room temperature (298 K) and a relatively high space velocity (1.2 × 105 mL g−1 h−1). The correlation between the microstructure of the FeOx support and the CO oxidation performance of the resultant Pt/FeOx catalyst was investigated. Although the oxidation of Pt nanoparticles is inevitable in the Pt loading process, relatively large amounts of Pt0 species can be preserved on the FeOx support possessing abundant surface hydroxides. In situ DRIFTS shows that the surface hydroxides on FeOx could also participate in the catalytic process; they could react with CO adsorbed on Pt0 sites and then recover easily in the co-presence of molecular oxygen and water gas. These results show that the intrinsic properties of the FeOx support not only affect the oxidation state of supported Pt nanoparticles in the preparation process, but also provide new active sites in the catalytic process. FeOx supports possessing abundant surface hydroxides are suitable for preparing high-performance Pt/FeOx catalysts for low-temperature CO oxidation.