Enhancing the Carbon Monoxide Oxidation Performance through Surface Defect Enrichment of Ceria-Based Supports for Platinum Catalyst.

Effective synthesis and application of single-atom catalysts on supports lacking enough defects remain a significant challenge in environmental catalysis. Herein, we present a universal defect-enrichment strategy to increase the surface defects of CeO2-based supports through H2 reduction pretreatment. The Pt catalysts supported by defective CeO2-based supports, including CeO2, CeZrOx, and CeO2/Al2O3 (CA), exhibit much higher Pt dispersion and CO oxidation activity upon reduction activation compared to their counterpart catalysts without defect enrichment. Specifically, Pt is present as embedded single atoms on the CA support with enriched surface defects (CA-HD) based on which the highly active catalyst showing embedded Pt clusters (PtC) with the bottom layer of Pt atoms substituting the Ce cations in the CeO2 surface lattice can be obtained through reduction activation. Embedded PtC can better facilitate CO adsorption and promote O2 activation at PtC-CeO2 interfaces, thereby contributing to the superior low-temperature CO oxidation activity of the Pt/CA-HD catalyst after activation.

Hydroxyls on CeO2 Support Promoting CuO/CeO2 Catalyst for Efficient CO Oxidation and NO Reduction by CO.

Transition metal catalysts, such as copper oxide, are more attractive alternatives to noble metal catalysts for emission control due to their higher abundance, lower cost, and excellent catalytic activity. In this study, we report the preparation and application of a novel CuO/CeO2 catalyst using a hydroxyl-rich Ce(OH)x support for CO oxidation and NO reduction by CO. Compared to the catalyst prepared from a regular CeO2 support, the new CuO/CeO2 catalyst prepared from the OH-rich Ce(OH)x (CuO/CeO2-OH) showed significantly higher catalytic activity under different testing conditions. The effect of OH species in the CeO2 support on the catalytic performance and physicochemical properties of the CuO/CeO2 catalyst was characterized in detail. It is demonstrated that the abundant OH species enhanced the CuOx dispersion on CeO2, increased the CuOx-CeO2 interfaces and surface defects, promoted the oxygen activation and mobility, and boosted the NO adsorption and dissociation on CuO/CeO2-OH, thus contributing to its superior catalytic activity for both CO oxidation and NO reduction by CO. These results suggest that the OH-rich Ce(OH)x is a superior support for the preparation of highly efficient metal catalysts for different applications.