Brij-58 template synthesis of self-assembled thermostable lamellar crystalline zirconia via a reflux-hydrothermal hybrid method

Abstract

Using polyoxyethylene-20-cetyl-ether (Brij-58) as a supramolecular template, thermostable lamellar crystalline zirconia (TSLCZ) was synthesized though the reflux-hydrothermal hybrid method (R-HT) with ZrOCl₂·8H₂O as the zirconium source and sodium hydroxide as the precipitating agent. The TSLCZs were characterized by XRD, TEM, SAED, FE-SEM, TG-DTA and FTIR. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses showed that zirconia is the only crystal phase in TSLCZ and Brij-58 promoted zirconia nucleation and 2D-growth and induced self-ordered lamellar nanostructured assembly. Transmission electron microscopic (TEM) observations further proved this regular lamellar structure, which was detected by XRD. The repeat periodicity of the structure is about 1.20 nm, as observed by TEM, which is in well accordance with the XRD data (1.19 nm). The selected area electron diffraction (SAED) results indicate that TSLCZ is a polycrystalline structure. XRD, TEM and field emission scanning electron microscopy (FE-SEM) results show that the TSLCZ can be well preserved even after a high temperature thermal treatment at 500 °C for 2 h. Moreover, the R-HT significantly promoted the Brij-58 directed synthesis of TSLCZ in the three aspects of heterogeneous nucleation, controlled 2-D growth and ordered lamellar self-assembly as compared to only the reflux (R) or hydrothermal (HT) method. The possible formation of the TSLCZ could be explained by the use of the surfactant template.