Synthesis, characterization, and 2,4-dichlorophenoxyacetic acid degradation on In-Na_2Ti_6O_(13) sol–gel prepared photocatalysts

摘要

Indium-Na_2Ti_6O_(13) doped semiconductors were prepared by the sol–gel method using titanium and sodium alkoxides as precursors. The gelled samples were annealed at 700 C for 4, 6, and 8 h, and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and UV–Vis diffused reflectance spectroscopy (DRS). XRD patterns of the samples show the formation of the Na_2Ti_6O_(13) phase, whose crystallinity depends on the annealing time. The band gap calculated from the UV–Vis Kubelka–Munk function report similar values (3.2–3.4 eV) for all of the samples annealed at different times. SEM observations of the semiconductors showed microfiber bundle morphologies of about 5 lm. Meanwhile, by EDS analysis, indium oxide highly homogeneously dispersed on the hexatitanate surface was identified. The evaluation of the In-Na_2Ti_6O_(13) semiconductors in the 2,4-dichlorophenoxyacetic acid (2,4-D) photodecomposition using ultraviolet light (λ = 254 nm) irradiation show that the photoactivity of the solids depends on the annealing time applied to the samples. The role of indium oxide is related to the indium oxide dispersed on the surface of the titanate diminishing the electron-hole recombination rate.