Solvothermal synthesis, characterization and photocatalytic property of zirconium dioxide doped titanium dioxide spinous hollow microspheres with sunflower pollen as bio-templates

Zirconium dioxide (ZrO₂) doped titanium dioxide (TiO₂) spinous hollow microspheres were successfully prepared through a facile solvothermal method using sunflower pollen as bio-templates. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), N₂ adsorption–desorption isotherms and UV–Vis diffuse reflectance spectroscopy. It was found that the products have spinous microsphere morphology with an approximate diameter of 12 μm. The ZrO₂ doped TiO₂ hollow microspheres exhibited a higher photocatalytic activity in the degradation of Rhodamine B (RhB) in aqueous solutions under UV-light irradiation compared with TiO₂ hollow microspheres and ZrO₂-doped TiO₂ particles. In particular, the removal of RhB followed pseudo-first-order kinetics, and 96.3% of RhB was degraded in 60 min under UV-light irradiation when ZrO₂ doped TiO₂ spinous hollow microspheres were used as the photocatalysts. Neutral and alkaline conditions were found to favor over acidic conditions for the photocatalytic degradation of RhB. Furthermore, scavenging experiments indicated that photogenerated holes (h⁺) and radicals (^[rad]OH and ^[rad]O⁻ ₂) were the main reactive species in the photocatalytic process using ZrO₂ doped TiO₂ hollow microspheres as the catalysts under UV light irradiation.