Structural and morphological characterizations of ZnO nanopowder synthesized by hydrothermal route using inorganic reactants

Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 °C for 2 h and then characterized by X-ray diffraction(XRD), scanning electron microscopy and infra-red Fourier transformed spectroscopy. XRD measurements have shown a Zn O hexagonal wurtzite polycrystalline structure with good crystallinity and the formation of a new sodium pyrosulfate phase in the as-prepared powder. The annealing improves the crystalline quality of the powder and transforms the sodium pyrosulfate phase to a sodium sulfate one. The thermal treatment does not affect the lattice parameters and the Zn–O bond length but improves the random orientation of the Zn O crystallites growth.Zn O crystallites have an interconnected-nano-needles morphology forming irregular shaped aggregates. The size of the crystallites is about 20 nm. EDX analysis has shown the presence of C and S in addition to Zn and O. FTIR spectra confirm the formation of Zn O and sodium sulfate. The synthesized Zn O powder has a very high crystalline quality and the used method is a very advantageous one for the fabrication of nanosized metal oxides from inorganic reactants for photo-catalysis applications.