A novel ethanol templating synthesis of ordered lamellar superstructured crystalline zirconia

Soft template technique has attracted great interest, because it is a facile, inexpensive and efficient synthesis strategy for ordered superstructural systems. Here, a novel ethanol template was used to synthesize the ordered lamellar superstructured crystalline zirconia (Lα-ZrO₂) without post-treatments and surfactants. ZrOCl₂ and NaOH were served as Zr source and precipitant, respectively. XRD analysis showed that Lα-ZrO₂ is crystalline. XPS spectra indicated the physical adsorption of ethanol molecules in Lα-ZrO₂. TEM further observed and proved the 1.36-nm period of superstructure detected and calculated by SAXRD (1.35 nm), which is composed of 0.68-nm thick ZrO₂ and pore alternatively. In contrast, the template-free ZrO₂ (TF-ZrO₂) presents no superstructure and is poorly crystallized. As a soft template, ethanol presents the roles of (i) inducing the growth of zirconia layers, (ii) directing the self-assembly of ordered lamellar superstructure, and (iii) decreasing the crystallization temperature. The possible mechanism of ethanol serving as a soft template was proposed and discussed in thermodynamics.