Architecture of yolk–shell structured mesoporous silica nanospheres for catalytic applications

Abstract

We report the design and realization of yolk–shell structured nanospheres with periodic mesoporous organosilica (PMO) nanospheres or noble metal nanoparticles encapsulated in mesoporous silica shells via a selective etching method. These architectures have well controlled structure, size and morphology. The yolk–shell structured PMO@SiO₂ nanoparticles can be precisely functionalized with different catalytic functionalities, even incompatible acidic and basic groups: the PMO core with amino (–NH₂) groups and the mesoporous silica shell with sulfonic acid (–SO₃H) groups. As a nanoreactor, the as-synthesized Au@SiO₂ nanospheres show faster reduction of 4-nitrophenol than that of nitrobenzene. Furthermore, the prepared PMO-NH₂@SiO₂-SO₃H nanoparticles can be used as bifunctional catalysts with highly efficient catalytic performance for catalyzing the deacetalization-Henry cascade reaction.