Enhanced photocatalytic activity,mechanism and potential application of Idoped-Bi4Ti3O12 photocatalysts

In this study, we have introduced iodine into Bi₄Ti₃O₁₂ (BTO) crystals with the aim of improving their photocatalytic activities in decomposing organic pollutants. The as-prepared I_doped-BTO photocatalysts were systematically analyzed by various techniques (e.g. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), as well as density functional theory calculation. It is confirmed that I element is successfully doped, as an I^? oxidation state, in the BTO crystals by substituting the O in the perovskite-like (Bi₂Ti₃O₁₀)^2? blocks. The photocatalytic activities between the I_x-BTO (x = 0, 0.2, 0.4, 0.6, and 0.8) samples were compared by the photodegradation of methylene blue (MB) under simulated-sunlight irradiation, revealing that I_0.4-BTO is the optimal photocatalyst having a photocatalytic activity about 3.0 times higher than that of parent BTO. Based on the experimental data and density functional theory calculation, the enhanced photocatalytic mechanism for the I_doped-BTO photocatalysts was proposed and discussed. To promote the potential application of the optimal I_0.4-BTO photocatalyst, its photocatalytic performances were further investigated by the photodegradation of ciprofloxacin, tetrabromobisphenol A, tetracycline hydrochloride and methyl orange/rhodamine B (RhB)/MB mixture dyes; moreover, the effect of inorganic anions and pH values on the MB photodegradation was also investigated.