Size-controlled synthesis of alumina nanoparticles through an additive-free reverse cation–anion double hydrolysis method

Abstract

Size-controlled alumina (Al2O3) nanoparticles have been successfully synthesized for the first time via a reverse cation–anion double hydrolysis (CADH) method without any additive, employing the starting material of NaAlO2 and Al(NO3)3·9H2O, AlCl3·6H2O, Al2(SO4)3·18H2O. The structures and properties of as-obtained samples were well characterized by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The Al2O3 samples prepared by CADH method using different aluminum salts have three different nanostructures. The as-synthesized clew-like Al2O3 was self-assembled by uniform nanosized cubic platelets with the side-length of 100–150nm, thickness of about 20nm. The length of these as-synthesized Al2O3 nanorods is about 150nm. The side-length of as-prepared irregular Al2O3 nanosheets is less than 50nm.