Impact of CaO-Modified γ-Al 2 O 3 Support on CO Oxidation Activity of Pt/LaFeO 3 Catalyst.

In this study, we prepared Pt/29.3 wt % LaFeO ₃ on a commercial carrier of γ-Al ₂ O ₃ by inserting a CaO interlayer between LaFeO ₃ and γ-Al ₂ O ₃ (i.e., Pt/LaFeO ₃ /CaO/γ-Al ₂ O ₃ ) via atomic layer deposition. With the interaction between CaO and LaFeO ₃ , the Pt supported on LaFeO ₃ /CaO/γ-Al ₂ O ₃ demonstrated diverse dispersion characteristics, with regions showing well-dispersed Pt particles of approximately 2 nm, while others displayed some larger Pt nanoparticles. Interestingly, after redox treatments, the CO adsorption over Pt/LaFeO ₃ /CaO/γ-Al ₂ O ₃ was significantly attenuated, and high-resolution transmission electron microscope analysis on the Pt surface revealed the presence of FeO _x layers covering the Pt. Postoxidation, a thick FeO _x layer was generated on Pt, leading to the inertness of the catalyst toward CO oxidation. However, after reduction, a thinner FeO _x layer (approximately two atomic layers) developed on Pt, which facilitated the oxidation of CO through the Pt-FeO _x interface.