One-step synthesis, characterization, and visible light photocatalytic activity of pure and Zn-doped SnO_2 nanoparticles

摘要

A one-step microwave irradiation route was used to synthesize undoped and Zn-doped SnO_2 nanoparticles for the first time. The morphologies, structures and optical properties of the as-prepared samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, UV-Vis spectra and photolumines-cence spectra analysis. The results clearly revealed that both the pure and doped samples had a tetragonal rutile-type structure and a space group of P42/mnm have formed directly during the microwave irradiation process. FESEM studies illustrate that both the pristine and Zn-doped SnO_2 form in spherical-shaped morphology with an average diameter around 41-32 nm, which is in good agreement with the average crystallite sizes calculated by Scherrer's formula. Optical studies reveal that both pristine and Zn-doped SnO_2 direct transitions occur with the bandgap energies in the range of 3.43-3.26 eV. The photocatalytic activities of the pure and Zn-doped SnO_2 samples were evaluated by the degradation of methylene blue rhodamine B in an aqueous solution under visible light irradiation. The photocatalytic activity and reusability of Zn (10 wt%)-doped SnO_2 was much higher than that of the pure SnO_2. The improvement mechanism by zinc doping was also discussed.