Oxidation of Toluene over the Pt-Embedded Mesoporous CeO₂ Hollow Nanospheres with Advanced Catalytic Performances

In this study, the novel Pt-embedded mesoporous CeO₂ hollow nanospheres (Pt-MS-CeO₂-H) with varying Pt contents (0.5-3.0 wt %) were facilely prepared. The Pt nanoparticles were one-pot embedded within the mesoporous shell of Pt-MS-CeO₂-H and assisted with the reduction Ostwald ripening process. The traditional preparation methods often face challenges, such as the uneven distribution or aggregation of nanoparticles, as well as difficulty in maintaining high catalytic activity at low Pt content. Compared with the traditional supported Pt/MS-CeO₂ catalyst, the embedding strategy facilitated precise control over the position, distribution, and uniformity of Pt nanoparticles within the CeO₂ mesoporous shell. Additionally, the encapsulation process of Pt nanoparticles played a pivotal role in generating oxygen vacancies and activating surface chemical adsorption of oxygen. Resultantly, the toluene oxidation performances of 1Pt-MS-CeO₂-H catalyst showed much lower T₉₀ (171 °C) than 1Pt/MS-CeO₂ (311 °C). To elucidate the underlying reasons, in situ diffuse reflectance infrared Fourier transform spectroscopy of toluene oxidation was employed to identify the reaction intermediates and pathways over these catalysts. In summary, the Pt-embedded mesoporous CeO₂ hollow nanosphere catalysts were considered as potential candidates when designing high-performance toluene catalytic oxidation catalysts.