Synthesis and characterization of zinc-aluminum based layered double hydroxide and oxide nanomaterials by performing different experimental parameters

Abstract

Zinc-aluminum based layered double hydroxide (ZnAl-LDH), -oxide (ZnO), -mixed oxide (Zn6Al2O9), and zinc-aluminum mixed oxide/polyvinyl alcohol (ZnAl-mixed oxide/PVA) nanocomposite have been synthesized. The samples were characterized using some analytical methods: Ultraviolet-visible spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, x-ray diffraction (XRD), scanning electron microscopy, and energy-dispersive x-ray spectroscopy. The XRD patterns of ZnAl-LDH5M and ZnAl-LDH2M show the characteristic reflections of ZnO phase beside the hydrotalcite-like structure. Using NaHCO3 in the experiment, the precipitation speed of the sample was high and in this regard, the particle size of ZnAl-LDHurea(1) was 22.37 nm. ZnAl-LDH2M and ZnAl-LDH5M describe three optical band gaps with three different energies. For ZnAl-mixed oxide/PVA, there are two types of electronic transitions could exist at ZnO which attributed to the filled O2p orbital and that associated to the empty Zn 4s orbital, with the possibility of some Zn 4p orbital. Another electronic transition could exist for Zn6Al2O9 between the filled O 2p orbital and the empty Al 3s orbitals, with the additional possibility of some Al 3p orbital. The intense FTIR band at very low wavenumber is observed for only ZnAl-LDHurea(2) which attributed to the Zn-O-bound for brucite-like LDH structures.