Large-scale synthesis of uniformly dispersed hexagram-like gibbsite by a controlled replacement reaction

Abstract

A facile, convenient, and mild method has been developed for large-scale synthesis of uniformly dispersed 2D six-pointed star-like gibbsite micro–nano crystals with lateral size around 2.5 μm and thickness around 100 nm, through a replacement reaction between Al powder and water. Investigation of the influence of solvent in a series allows for conclusion that replacing the reactant solvent water with ethylene glycol not only effectively moderates the reaction, but also benefits control of shape, crystal structure, and dispersibility. In contrast, besides decreasing the reaction speed, the same function cannot be attributed to another inorganic solvent candidate absolute ethanol. This conclusion was supported by XRD, FE-SEM, TEM, FT-IR, TGA and PSD measurements. Moreover, the band gap of as-prepared gibbsite powder in EG–H₂O mixture is 5.78 eV, which is mainly attributed to its surface low coordinated O²⁻. Theoretically, scale-up of this simple synthetic procedure for large-scale production of gibbsite powder with high crystallinity and purity should be very easy.