Manipulating the Size and Morphology of Aluminium Hydrous Oxide Nanoparticles by Soft-Chemistry Approaches

Abstract

We demonstrate control of the size and morphology of aluminum hydrate nanoparticles synthesized by a hydrothermal reaction through manipulating pH value of the reaction mixture, hydrothermal temperature and the surfactant used. Porous laths formed under acidic conditions, while the lath-width increased with temperature and single-crystal porous laths were formed. At neutral or high pH values, porous plates of several nanometers thick were obtained. The pore sizes on both laths and plates were ~2-3 nm. Stringy lath-shaped nanoparticles were obtained with polyethylene glycol surfactant. It demonstrates that we can precisely control nanoparticle size and morphology using soft chemical methods. Furthermore, these nanoparticles transformed to y-alumina nanocrystallites after heating to 673K, and retained the morphology of the parent boehmite. We provide a detailed characterization of the nanoparticulates and discuss the mechanism of their formation and subsequent transformation