Revealing the Role of H2 in Promoting CO Oxidation Durability over Pt-CeO2.

Pt-CeO2 is highly active for CO oxidation but suffers rapid deactivation due to the oxidation of Pt nanoparticles into less-active PtOx. Here, we introduce H2 into the CO oxidation feed gas to dynamically stabilize Pt in its metallic state. The H2/CO ratio is critical at an optimal ratio of 2, adding H2 significantly enhances both activity and durability, with complete CO conversion maintained for more than 110 h at 95 °C over 2Pt-CeO2, while it only kept 0.4 h under H2-free condition. In-situ infrared spectroscopy, near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), and density functional theory (DFT) calculations reveal that H2 does not merely consume O2; it preferentially reacts with the coordinated oxygen in PtOx species, thereby preserving metallic Pt throughout the reaction. This work demonstrates a dynamic gas-phase strategy to overcome the activity-stability tradeoff in Pt-CeO2 catalysts.