Rapid synthesis, characterization and optical properties of TiO2 coated ZnO nanocomposite particles by a novel microwave irradiation method

A novel and rapid microwave method was used to prepare TiO2 coated ZnO nanocomposite particles. The resulted particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Results show that ZnO nanoparticles were coated with 6–10 nm amorphous TiO2 layers. In addition, zeta potential analysis demonstrated the presence of TiO2 layer on the surface of ZnO nanoparticles. Photoluminescence (PL) spectroscopy and UV–visible spectroscopy were used to investigate the optical properties of the nanoparticles. Compared to uncoated ZnO nanoparticles, the TiO2 coated ZnO nanoparticles showed enhanced UV emission. The UV–visible diffuse reflectance study revealed the significant UV shielding characteristics of the nanocomposite particles. Moreover, amorphous TiO2 coating effectively reduced the photocatalytic activity of ZnO nanoparticles as evidenced by the photodegradation of Orange G with uncoated and TiO2 coated ZnO nanoparticles under UV radiation.