Enhanced surface oxygen transfer induced by strong Pd–CeO2 interaction for boosting catalytic soot oxidation
CeO 2 , a pivotal rare earth oxide in environmental catalysis, has garnered extensive interest for soot oxidation owing to its exceptional oxygen storage capacity and oxygen vacancy-rich surfaces. To further optimize catalytic efficiency, we engineered spherical CeO 2 with exposed (111) facets via hydrothermal synthesis and uniformly anchored Pd species through a gas bubbling-assisted membrane reduction (GBMR) strategy. The formation of Pd–O–Ce interfacial units is identified as critical active sites, where metal-support interaction (MSI) significantly enhances oxygen transfer. Notably, the Pd 1.0 /CeO 2 catalyst achieves a remarkable T 50 of 356 °C (14% lower than pristine CeO 2 ), attributed to highly dispersed Pd species and abundant Pd–O–Ce interfaces. In contrast, excessive Pd species loading induces particle agglomeration, weakening MSI effect and catalytic performance. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional thoery (DFT) calculations reveal that the Pd–O–Ce interface promotes NO adsorption – the rate limiting step – by generating electron-rich Pd sites and oxygen vacancies, thereby accelerating NO-to-NO 2 conversion and subsequent soot oxidation. This work highlights the pivotal role of interfacial engineering in optimizing Pd–CeO 2 catalysts, offering a rational design strategy for high-performance soot oxidation systems in diesel emission control.
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