Synchronous synthesis/modification of multifunctional hollow silica nanospheres through selective etching and application in catalysis

Abstract

An effective selective etching strategy has been developed to simultaneously synthesize and modify multifunctional hollow SiO2 nanospheres (HSNs). The key point of this strategy lies in the utilization of (3-aminopropyl)triethoxysilane (APTES) or H2SO4 to etch core-shell composite particles, which contribute to the grafting or transformation of organic functional groups in multifunctional HSNs during the etching process. In our study, cyano-SiO2@cyano-thiol-SiO2 (CN-SiO2@SH-CN-SiO2) composite particles were firstly synthesized by two-step sol-gel reaction of 2-cyanoethyltriethoxysliane (CTES) and 3-mercaptopropyltrimethoxysilane (MPTMS), and then the obtained composite particles could be transformed to be different type of multifunctional HSNs (SH-CN-NH2-HSNs and SH-COOH-HSNs) after respectively etched by APTES or H2SO4. The selective etching strategy greatly simplifies the procedures of preparing multifunctional HSNs. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have demonstrated the hollow structure, and it’s found that the morphology of SH-CN-NH2-HSNs can be regularly changed by manipulating the amount of APTES. Fourier transform infrared (FT-IR) and elemental analyzer have also confirmed that the corresponding organic groups certainly exist in the obtained multifunctional HSNs. In addition, when the as-prepared multifunctional hollow SiO2 spheres were loaded with Au nanoparticles, the composite nanoreactor presented high activity for the catalytic reduction of p-nitrophenol.