Synthesis of mesoporous silicon directly from silicalite-1 single crystals and its response to thermal diffusion of ZnO clusters

This article describes the preparation of mesoporous silicon granules with a layered structure directly from silicalite-1 single crystals. The silicalite-1 single crystals were thermally reduced in vacuum at 630 °C, with the original shape retained. The samples are confirmed as crystalline silicon by X-ray diffraction and transmission electron microscope. The silicon granule is composed of a monocrystalline surface and polycrystalline layered interior. A surface area of around 66 m² g⁻¹ and the pore size centered at 3.7 nm were obtained from nitrogen porosimetry, BET and BJH analysis. The ZnO clusters have been loaded into the porous silicon granule by thermal diffusion method. The photoluminescence emission centered at 3.44 eV originates from the small particles of ZnO and the band at 2.81 eV may be due to both an oxidized surface and quantum confinement effects. The microstructure in this silicon granule is very different from those in etched samples. The synthetic design demonstrates an interesting way from the microporous zeolite to mesoporous silicon and enlarges the structural diversity of porous silicon crystal.