Template-free Synthesis and Formation Mechanism of Urchin-like Boehmite Superstructure

Novel urchin-like boehmite (AlOOH) superstructures consisting of nanorods were successfully synthesized by a template-free hydrothermal synthetic route in an ethanol-water solution. The crystal structures and the morphologies of boehmites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected area electron diffraction (SAED). The effects of the precursors, the volume ratio of EtOH/H2O and reaction temperatures on the morphologies were also discussed. It is shown that the 3D urchin-like boehmite of uniform morphology and good dispersibility is prepared using AlCl3·6H2O as the precursor at 200 ith the volume ratio (EtOH/H2O) of 1:2. The diameter of the urchin-like boehmite is 6-10μm, which is consisted of nanorods with the diameter of 60-80nm. The SAED pattern reveals the polycrystalline nature of the urchin-like boehmite. The oriented attachment mechanism plays a key role on the formation of urchin-like boehmite superstructures.