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