Nanocrystal Templating of Silica Mesopores with Tunable Pore Sizes

Metallic nanoparticles (platinum and gold) encapsulated in mesoporous silica (SBA-15) were prepared in the same solution by a novel two-step method. Characterization by X-ray scattering and electron microscopy consistently shows that the metal nanoparticles were homogeneously incorporated in the mesopores (retaining their size and morphology), even when the nanocrystal diameter exceeds the normal mesopore diameter. The nanoparticles nucleated the expansion of the mesopore channels in the 92−116 Å range so they could accommodate the metal particles. This expansion occurs in the concentration range of 1−103 nanoparticles per 103 mesopore channels. This effect can be used to tune the pore size.