Preparation of highly dispersed Pt catalyst by CeOx 'islands' modification of dendritic mesoporous SiO2: CO as a probe molecule

Abstract

There are still challenges in producing noble metal catalysts with atomic dispersion on a large scale in current. This study presents a method for preparing a highly dispersed Pt catalyst (Pt/CeOx/DMS) by modifying dendritic mesoporous SiO2 (DMS) with CeOx 'islands'. The results demonstrate that Pt is highly dispersed on the CeOx/DMS carrier, with the majority of Pt existing in the form of single atoms (Pt/20 wt.% CeOx/DMS). The dendritic DMS has a large specific area (451 m2 g−1) that provides more sites for the formation of CeOx 'islands'. This promotes the dispersion of Pt, significantly improving the oxidation activity of CO. The addition of CeOx 'islands' to the Pt/DMS catalyst promotes the desorption of CO on Pt NPs, enhances the adsorption and activation of O2, and further improves the activity of catalyst. This is because of the synergistic effect between Pt and CeOx 'islands'. The DFT result found that it is more beneficial for Pt1 to adsorb O2 before other reactions. To test the activity and stability of the catalyst, the team conducted catalytic oxidation of CO as a model reaction. The results show that the promotion of CeOx 'island' reduces T90 of CO catalytic oxidation by 16 ℃. In the high-temperature stability test of the catalyst, it was observed that even after reacting at 500 ℃ for 8 h, the catalyst can still achieve 90 % conversion of CO at 147 ℃, demonstrating its good stability. This study provides a foundation for designing a new type of CO oxidation catalyst. The catalyst features high dispersion Pt and exhibits excellent catalytic activity.