Enhanced photocatalytic degradation of rhodamine B, methylene blue and 4-nitrophenol under visible light irradiation using TiO_2/MgZnAl layered double hydroxide

摘要

Abstract Series of new TiO~(2)/MgZnAl layered double hydroxide (TiO~(2)/LDH) composites with different molar ratio of metals (Mg:Zn:Al) and a certain amount of recombined TiO~(2)were successfully prepared by co-precipitation method. The prepared products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, N~(2)adsorption–desorption measurements, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance spectroscopy. Rhodamine B (10 mg/L), methylene blue (10 mg/L) and 4-nitrophenol (4 mg/L) were used as model organic compounds for evaluation of the photocatalytic performance of the as-prepared photocatalysts under visible light irradiation. Results indicated that TiO~(2)/LDH composites (Mg:Zn:Al equals to 1:3:1) showed the highest photocatalytic activity and degraded 93.73, 85.88 and 89.33% of rhodamine B, methylene blue, and 4-nitrophenol in 9.0, 8.0 and 4.0 h, respectively. By comparison, the composites exhibited superior photocatalytic activity compared to P25 catalysts. The enhanced photocatalytic activity of the TiO~(2)/LDH composites mainly attributed to the efficient separation of photoinduced electrons and holes. Superoxide radicals and holes were the major active species. What’s more, the as-prepared photocatalysts exhibited remarkable stability and reusability. Besides, the possible degradation mechanism of rhodamine B, methylene blue and 4-nitrophenol also were proposed in this paper. This work provides an effective way to prepare series of LDH-based photocatalysts.