Synthesis, characterization, and 2,4-dichlorophenoxyacetic acid degradation on In-Na2Ti6O13 sol–gel prepared photocatalysts
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Indium-Na2Ti6O13 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 Na2Ti6O13 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 μm. Meanwhile, by EDS analysis, indium oxide highly homogeneously dispersed on the hexatitanate surface was identified. The evaluation of the In-Na2Ti6O13 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.
KeywordsIndium-doped semiconductors Alkali titanates XRD Alkali titanates SEM-EDS In2O3-alkali titanates 2,4-D photodegradation
The authors would like to acknowledge the technical assistance provided by M. Ruiz Gómez (SEM-EDS). V. Rodríguez González would like to thank the PROMEP 103.5/08/3125 UANL-PTC-244 project.
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