Template-free solvothermal synthesis of 3D hierarchical nanostructured boehmite assembled by nanosheets

In the absence of template and surfactant, hierarchical nanostructured boehmite was synthesized via a simple solvothermal route using aluminum nitrate as aluminum source and isopropanol–toluene mixture as solvent. The crystal structures, morphologies and textural properties of products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption–desorption technique. The as-obtained hierarchical nanostructures consist of nanosheets keeping Brunauer–Emmett–Teller (BET) specific surface area and pore volume of ca. 264.7 m2/g and 1.2 cm3/g, respectively. The experimental results show that the longer reaction time and the lower reaction temperature are unfavorable to the formation of hierarchical nanostructures. Moreover, the properties of solvent have important influence on the morphology of product. The possible formation mechanism of boehmite hierarchical nanostructures was proposed and discussed.

► Hierarchical nanostructured boehmite assembled by nanosheets was prepared via a template free solvothermal route.
► Both long reaction time and high temperature promote the generation and growth of boehmite nanocrystallites.
► The relative large molecule size of alkyl alcohol is favor of separation of boehmite particles.