Self-assembly of hollow spherical nanocatalysts with encapsulated Pt NPs and the effect of Ce-dipping on catalytic activity

Abstract

This article reports a facile and controllable one-step method to construct Pt@hollow mesoporous SiO₂ (Pt@HMSiO₂) nanoparticles (NPs). To enhance the catalytic activity, cerium species were impregnated into Pt@HMSiO₂ NPs, fabricating highly reactive Pt–CeO₂@HMSiO₂ NPs. To verify the successful synthesis of the Pt@HMSiO₂ and Pt–CeO₂@HMSiO₂ NPs, and study the influence of CeO₂ species on the catalytic performance, the as-prepared NPs were characterized by several techniques, including SEM, TEM, EDX, FTIR, XRD, BET and UV-vis analyses. In this work, the reduction of 4-NP was employed as a model reaction to test the catalytic performance. Compared to Pt@HMSiO₂, the Pt–CeO₂@HMSiO₂ NPs show higher catalytic activity, because of the co-catalysis of CeO₂ NPs. However, the excess amount of CeO₂ NPs would lead to a lower catalytic activity, due to the blocking of the catalyst pore. In addition, the Pt–CeO₂@HMSiO₂ NPs show a high thermal stability due to the protection of the SiO₂ shell. Meanwhile, we have also used the reaction of propane dehydrogenation to further verify the excellent catalytic stability of Pt–CeO₂@HMSiO₂ NPs. This strategy is novel, albeit efficient, and can be extended to the preparation of other nanocatalysts.