Hierarchically porous Fe2O3 and Fe2O3/SiO2 composites prepared by cypress tissue template with assistance of supercritical CO2

Abstract

Hierarchically porous α-Fe2O3 and silica-based Fe2O3 composites (I & II) ranging from nanopores to micrometer-sized pores have been prepared by a nanoscale casting process, using cypress wood tissue template in supercritical carbon dioxide (scCO2). These wood-templated Fe2O3 and its SiO2-based composites with special hierarchical but continuous pore size from 9 nm up to 20 μm, were prepared from scCO2’ hybrid solution with cosolvent and precursor(s). Different characterization techniques such as SEM, XRD, and N2 adsorption-desorption were used to investtig-ate the morphology and structure of Fe2O3 and its composites in different length scales. The Fe2O3 porous material showed a specific character-istic of being accumulated by Fe2O3 granules in the size range ca. 100–200 nm. The SiO2-based Fe2O3 composites exhibited a BET area of 99–104 m2/g, which was much higher than that of pure Fe2O3; this implies that the silica probably exists in the form of a gel skeleton.