Preparation and characterization of visible-light driven La/Mg co-doped ZnO photocatalyst

ZnO and LaxMg0.03-xZn0.97O (x = 0.01, 0.015 and 0.02) nanoparticles prepared by combustion method were used for photocatalytic degradation of methylene blue (MB) as a dye model under visible light irradiation. Phase, morphology, surface area and optical properties of the samples were characterized by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller surface area analysis and UV-Visible spectrometry. The samples were indexed to pure hexagonal wurtzite ZnO nanoparticles with average particle size 115.64 +/- 41.13, 67.25 +/- 15.54, 36.80 +/- 11.74 and 19.32 +/- 4.11 nm for ZnO, La0.01Mg0.02Zn0.97O, La0.015Mg0.015Zn0.97O and La0.02Mg0.01Zn0.97O samples, respectively. UV-Visible spectroscopy of ZnO nanoparticles has excellent absorption in UV region of 380 nm which was shifted to 384 nm for La0.02Mg0.01Zn0.97O nanoparticles by the incorporation of La/Mg dopants into the ZnO matrix. The photocatalytic efficiencies of ZnO, La0.01Mg0.02Zn0.97O, La0.015Mg0.015Zn0.97O and La0.02Mg0.01Zn0.97O nanoparticles for MB degradation were 10.90%, 92.33%, 96.01% and 97.10%, respectively. The La0.02Mg0.01Zn0.97O nanoparticles have the highest photocatalytic activity because La/Mg co-dopant played the role in suppressing electrons-holes recombination and enhancing the photocatalytic activity of ZnO nanoparticles induced by visible radiation.