Synthesis of ZnOAl2O3 core-shell nanocomposite materials by fast and facile microwave irradiation method and investigation of their optical properties

Abstract Alumina (Al 2 O 3 ) coated ZnO core-shell structures were synthesized by a novel, fast, and facile route utilizing microwave (MW) irradiation to control photocatalytic property of ZnO. The phase analysis and the core–shell structure development were corroborated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FT-IR). The XPS results affirmed that elements on the coated surface were Al and O. Zeta potential analysis predicted the presence of Al 2 O 3 layer on ZnO due to almost similar zeta potential curve for pure Al 2 O 3 and Al 2 O 3 coated ZnO nanoparticles. There was no significant change in band gap energy of ZnO after amorphous Al 2 O 3 coating as obtained from derived data of the reflectance spectra but gradual decreasing of reflectance in the visible range, measured by UV–vis spectroscopy, of the prepared core-shell nanoparticle may be due to the coating of amorphous Al 2 O 3 on ZnO. The photocatalytic efficiency of ZnO was reduced after amorphous Al 2 O 3 layer as confirmed by the photodegradation of methylene blue under UV irradiation.