Enhanced photoluminescence and photocatalytic activity of ZnO-ZnWO4 nanocomposites synthesized by a precipitation method

Zinc oxide (ZnO)-zinc tungstate (ZnWO4) nanocomposites ((ZnO)1−x(ZnWO4)x, x=0, 0.1, 0.2, 0.3, 0.5, 0.7, 0.9, 1) were prepared using a convenient precipitation method. The structural, morphological and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Ultraviolet-visible (UV–vis) absorbance measurements and photoluminescence (PL) spectroscopy. The photocatalytic performance of the samples was evaluated utilizing methyl orange (MO) under UV light irradiation. The SEM and HR-TEM analyses revealed that an intimate contact was possibly formed at the ZnO-ZnWO4 interface. The PL spectra of the composites of ZnO and ZnWO4 exhibited a stronger blue-green emission band in the range of 400–540 nm under 272 nm radiations compared with that of single phase ZnWO4. And their photocatalytic performances were also elevated significantly when the value of the x was 0.1, 0.2, 0.3 and 0.5, almost twice as much to that of ZnO. The superior fluorescent and photocatalytic performances might be ascribed to the suitable energy levels related to the intimate contact between two different semiconductors, which are beneficial to the interfacial charge transfer between the conduction and valence bands.