Hollow Pt/CeO2 nanocatalysts pretreated with pulsed steam for enhanced CO oxidation performance

The supported Pt/CeO₂ catalysts are widely used for the catalytic oxidation of CO at ambient conditions. Herein, we reported a new strategy for modifying the interaction between Pt and CeO₂ support via pulsed steam treatment, which significantly optimized the catalytic performance of Pt/CeO₂ for CO oxidation. Specifically, the hollow CeO₂ nanospheres were prepared by using carbon spheres as sacrificial templates and then subjected to pulsed steam treatment at 150 °C for different times to obtain the CeO₂-xH support (x means the time of pulsed steam treatment, min). It was found that the complete oxidation of CO can be achieved at 90 °C over the Pt/CeO₂–50H sample, which was much lower than that (130 °C) on Pt/CeO₂ without pulsed steam treatment. The XPS and in-situ DRIFTS characterizations were conducted to reveal the high performance of the Pt/CeO₂–50H catalyst for CO oxidation. It was found that the valence state of Pt significantly controlled by pulsed steam treatment was critical to the catalytic activity, whereby the presence of two types of active sites (Pt⁰-CO and Pt^δ+-CO) over Pt/CeO₂–50H greatly promoted the combination of adsorbed CO and O₂ to generate CO₂. Accordingly, this study provides a facile method to regulate the Pt valence state by pulsed steam treatment for CeO₂ support, which is critical to the CO oxidation activity.