Encapsulation of Metal (Au, Ag, Pt) Nanoparticles into the Mesoporous SBA-15 Structure

Mesoporous silica was synthesized in the presence of metal (Au, Pt, and Ag) nanoparticles in the 2−20 nm range. Sample characterization was performed by X-ray diffraction and electron microscopy. The metal nanoparticles in the 2−10 nm range were successfully incorporated into the ordered mesoporous SBA-15 structures; 20 nm particles, whose diameter is larger than the SBA-15 pore size, could not be inserted. In the case of 5 and 10 nm diameter nanoparticles, regardless of which metal, the mesopore channels expanded in order to accommodate the metal particles. By using mixtures of metal nanoparticles of two different sizes, it was found that the inclusion and the resultant pore size were controlled by the larger size metal particles.