HRTEM of negative replicas of mesoporous silica

Mesoporous silica SBA-15 has been used to synthesize its negative replicas of crystalline transition metal oxides, Cr2O3, WO3, V2O5, MnO2 and CuO. After removing the silica templates, the detailed structures of the produced nanoparticles, nanorods and 3D porous single crystals were investigated by using high resolution transmission electron microscopy (HRTEM). Formation mechanisms of these replicas were studied based on the HRTEM observations of the series specimens with different experimental conditions. Surface structures of the nanorods were revealed by HRTEM surface profile imaging so that the morphologies of the nanorods in these materials could be investigated in order to reveal the sizes and shapes of mesopores in the silica templates. When the whole inner space in SBA-15 is filled by metal oxides, the products become 3D porous single crystals, which is a new class of self-supported nanoparticle catalysts.