Surfactant-assisted selective etching strategy for generation of rattle-like mesoporous silica nanoparticles

Nowadays, rattle-like or so-called yolk-shell nanostructures have set off a new wave of research in view of their prominent features including large surface area, tunable void and flexible functional core, etc. Herein, rattle-like mesoporous silica nanoparticles (RMSNs) with a pure silica core, a hollow cavity and a mesoporous shell have been successfully fabricated via a surfactant-assisted selective etching strategy. The synthetic approach involves the preparation of solid silica spheres with three-layer different structural silica containing the inner core of pure silica, middle layer of hybrid silica and outer shell of surfactant/SiO₂ composite, followed by a hydrothermal treatment in hot water. The resulting products show a distinct rattle-like structure and spherical morphology. The average diameter, the shell thickness, and the solid core size of RMSNs are about 290, 35 and 90nm, respectively. During the etching process, the surfactant with different length of alkyl chain (C_nTAB, e.g. cetyltrimethylammonium bromide) in outer shell plays a decisive role for the formation of rattle-like structure. Benefiting from the residual amino groups in RMSNs, Au@RMSNs composites can be further constructed by in-situ generating Au nanoparticles into their hollow cavity, demonstrating an excellent catalytic performance for reduction of 4-nitrophenol. Additionally, RMSNs also show a strong ability for adsorption of rhodamine B.