Tailoring porosity and dimensionality of Co₃O₄ nanophase using channel interconnectivity control by steaming of nanocasting SBA-15

Two-dimensional hexagonal arrays of interconnected Co₃O₄ nano-rods or disconnected mono-dimensional Co₃O₄ nano-rods were nano-cast fabricated using SBA-15 as hard template with or without intra-wall microporosity, respectively. A clean, efficient and facile high temperature steam post-treatment is proposed to control the microporosity and the interconnectivity of the nanocasted oxide phase. Characterization by small-angle X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) suggests that the selective removal of micropores is resulted from hydrothermal restructuring within the pore wall of calcined SBA-15 followed by a sequential process, including hydrolysis and re-condensation of internal surface siloxane bonds and dissolution-migration-deposition of amorphous debris external onto the SBA-15 under the atmosphere of pure water vapor.