Impact of CaO-Modified γ-Al2O3 Support on CO Oxidation Activity of Pt/LaFeO3 Catalyst

In this study, we prepared Pt/29.3 wt % LaFeO3 on a commercial carrier of γ-Al2O3 by inserting a CaO interlayer between LaFeO3 and γ-Al2O3 (i.e., Pt/LaFeO3/CaO/γ-Al2O3) via atomic layer deposition. With the interaction between CaO and LaFeO3, the Pt supported on LaFeO3/CaO/γ-Al2O3 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/LaFeO3/CaO/γ-Al2O3 was significantly attenuated, and high-resolution transmission electron microscope analysis on the Pt surface revealed the presence of FeOx layers covering the Pt. Postoxidation, a thick FeOx layer was generated on Pt, leading to the inertness of the catalyst toward CO oxidation. However, after reduction, a thinner FeOx layer (approximately two atomic layers) developed on Pt, which facilitated the oxidation of CO through the Pt–FeOx interface.