Fabrication of Zinc-Iron-Aluminum Layered Double Hydroxides with Controlled Micromorphology in a Tailored Aqueous - Organic Synthesis Medium

Abstract

Micromorphology characteristics of layered double hydroxides are important to establish their performances to act as adsorbents and catalysts/photocatalysts. Herein, we report the fabrication of ZnFeAl layered double hydroxides (LDHs) (defined by a molar ratios Zn/Fe/Al 2/0.5/0.5), in a tailored aqueous-organic synthesis medium, by using the coprecipitation method. The nature of the organic solvent (e.g.: ethanol, ethyl acetate, glycerol and toluene) was used as a controlled variable for obtaining specific morphology characteristics of ZnFeAl. XRD, FTIR, UV-Vis-DR spectroscopy and SEM microscopy have been used to characterize the structural, optical and textural features of ZnFeAl. Results show that the controlled aqueous-organic synthesis medium established important changes in the structural features and the micromorphology characteristics (e.g.: particle sizes and their interconnection patterns) of ZnFeAl, as indicated by the results of XRD and SEM analyses. The FTIR spectra revealed that most of the interlayer anions are carbonate, even though the initial salts precursors contain nitrates or sulfates anions. Furthermore, the UV-Vis-DR results underline that the band gaps of the LDH derived oxides changed in a significant manner, as a function of the nature of the organic solvent. Such that, ZnFeAl prepared in the presence of ethanol and ethyl acetate show band gap values lower than 3 eV and thus could be better activated under visible light. These results should be inspiring for fabricating layered double hydroxides with a controlled micromorphology for specific applications for environmental cleanup.