Assembly of γ-Alumina Nanorods via Supercritical Technology

Various of nano alumina with desired size and morphology have been synthesized for different applications. In this study, we report the preparation of γ-alumina nanorods with a diameter of 15–45 nm and a length of 60–150 nm, which aggregated into a typical morphology of nanosheets. The formation mechanism is assumed to discuss the fabrication process of unique structure. γ-Al₂O₃ nanorods are obtained after the annealing process to precursor natroalunite nanosheets synthesized by hydrothermal treatment of the sol in the presence of supercritical carbon dioxide. The precursor natroalunite and alumina are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ sorption isotherm, and TG-DSC