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

• Facile and efficient removal of micropores in SBA-15 silica by high temperature water steaming post-treatment.
• A two-step mechanism of the pore morphology evolution upon steaming before structure collapse.
• Co3O4 nanoparticles with defined dimensionality was controlled synthesized.

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.

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