ZnO/Bi2O3 nanowire composites as a new family of photocatalysts

Zinc-bismuth oxide-peroxide (ZnO∗ ZnO2 ∗ Bi2O3) nanorod-like particles were prepared for photocatalytic application by the thermal hydrolysis of a zinc-peroxyl-complex precursor. Bi3 + doping has a strong effect on the morphological structure of the resulting product: lower Bi3 + concentrations preferentially form nanorods, whereas higher Bi3 + concentrations preferentially form a flower-like morphology. The synthesised samples of zinc-bismuth oxide-peroxides were examined by X-ray diffraction, Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy and nitrogen adsorption-desorption isotherm analysis. Electron spin resonance (ESR) was used to monitor the hydroxyl radicals HO on the zinc surfaces. The photocatalytic activity of the prepared samples was determined under the photocatalytic decomposition of Orange II dye in an aqueous slurry under UV or visible light irradiation. The best photocatalytic activity was achieved for the sample denoted ZnP175Bi_400, which includes 45.4 wt.% Bi2O3. The annealing of the samples at 400 °C increased the photocatalytic activity, mainly in the visible region.