Deposition of boehmite on carbon nanofibers using aluminum alkoxide and its thermal transformation

We attempted to prepare carbon nanofibers (CNFs) bonded chemically with alumina particles using acid-treated CNFs and aluminum sec-butoxide. The structure and morphology of the boehmite deposited on the CNFs, the boundary between the CNFs and the deposited boehmite, and the thermal transformation of the deposited boehmite were investigated using Raman spectroscopy, X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The boehmite deposited not only particulately on the CNFs but also in a film-like manner on parts of the CNFs. In addition, the boehmite could deposit not only on the disordered inner walls of the CNFs but also on the ordered inner walls. By heating at 1200 °C, the boehmite on the CNFs was transformed into α-alumina and θ-alumina. At this time, some alumina particles, particularly those formed on the ordered inner walls of CNFs, fell out of the CNFs, and only those alumina particles which might chemically bond with CNFs remained on the CNFs. Finally, CNFs dotted with alumina particles with a size of <50 nm were obtained.