Preparation of mesoporous ZnAl(2)O(4) nanoflakes by ion exchange from a Na-dawsonite parent material in the presence of an ionic liquid

Herein, mesoporous ZnAl(2)O(4) spinel nanoflakes were prepared by an ion-exchange method from a Na-dawsonite parent material in the presence of an ionic liquid, 1-butyl-2,3-dimethylimidazolium chloride ([bdmim][Cl]), followed by calcination at 700 °C for 2 h. The as-obtained products were characterized by several techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The ZnAl(2)O(4) nanoflakes with the thickness of ∼20 nm were composed of numerous nanoparticles, which resulted in a high specific surface area of 245 m(2) g(−1). The formation mechanism of the ZnAl(2)O(4) nanoflakes was comprehensively investigated, and the results showed that a 2D growth process of the Zn(6)Al(2)(OH)(16)(CO(3))·4H(2)O crystallites with the assistance of [bdmim][Cl] was the key for the induction of ZnAl(2)O(4) nanoflakes. Moreover, mesopores were formed between adjacent nanoparticles due to the release of CO(2) and H(2)O molecules from Zn(6)Al(2)(OH)(16)(CO(3))·4H(2)O during the calcination process.