Synthesis of Bismuth Oxyhalide (BiOBrzI(1-z)) Solid Solutions for Photodegradation of Methylene Dye

BiOBr_zI_(1-z) (0 ≤ z ≤ 1) materials were successfully prepared through hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) was used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr_zI_(1-z) materials was examined through methylene blue (MB) degradation under ultraviolet (UV) light and solar irradiation. The XRD shows that BiOBr_zI_(1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with increase in the amount of iodide (I^-). BiOBr_0.6I_0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99 and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBr_zI_(1-z) materials shows that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h⁺) and superoxide radicals (^•O₂⁻) are the key species responsible for the degradation of MB. The experimental results agree with nonlinear fitting.