Thermally stable and highly active Pt/CeO2@SiO2 catalysts with a porous/hollow structure

Abstract

The encapsulation of noble metal nanoparticles (NPs) into SiO₂ has been widely demonstrated to be a good strategy to prevent NPs from sintering at high temperature. However, in most cases, the protective dense, thick SiO₂ shell may retard the diffusion of reactant and product molecules, thus inhibiting the catalytic activity. And the size of encapsulated noble metal NPs is always big (>1 nm). Most importantly, their integration with active metal oxides (e.g. CeO₂) and the creation of porous/hollow structure surrounded by SiO₂ are still rarely reported at present. Herein, we propose an efficient way to acquire thermally stable and highly active Pt/CeO₂@SiO₂ catalysts with a porous/hollow structure. The synthetic procedure starts with co-encapsulation of Pt NPs and Ce–Cu bimetal oxide into SiO₂ using a microemulsion method, followed by selective etching of CuO with dilute acid. Thanks to the ultra-small size of Pt NPs (<1 nm), the synergistic effect between Pt and CeO₂, the beneficial porous/hollow structure for reactant and product molecule diffusion, and the effective protection by the SiO₂ shell, the catalyst exhibits high catalytic activity and remarkable durability toward CO oxidation.