Synthesis and characterization of nanosized zinc aluminate spinel from a novel Zn-Al layered double hydroxide precursor

摘要

In this paper, a novel Zn-Al layered double hydroxide (LDH) with composition [ZnAl_2(OH)_6]CO_3-nH_2O was prepared using the urea method. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed its layered crystalline structure. Nanosized zinc aluminate spinel was successfully synthesized by calcining [ZnAl_2(OH)_6]CO_3nH_2O at the temperatures 700 °C or above. The formation of ZnAl_2O_4 was monitored via XRD, Fourier transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG-DTA). The optical and textural properties of the Zn-Al LDH and its calcined products were studied via UV-vis diffuse reflection spectroscopy and nitrogen sorption analysis. The band gap value of the sample calcined at 900 °C is in the range of 3.8-4.0 eV and the specific surface area decreases with increasing calcination temperatures.