Effect of pH on crystalline structure, morphology and visible-light-driven photocatalysis of BiOBr samples hydrothermally synthesized in solutions with the pH of 2–10 was investigated. The as-synthesized BiOBr samples investigated by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. In this research, the as-synthesized samples are pure tetragonal BiOBr phase at the pH of 2–10, and were composed of microplates, nanoplates and hierarchical micro-flowers controlled by the solution pH. The as-synthesized sample at the pH 8 was revealed the presence of Bi 4f, O 1s and Br 3d. Visible-light-driven photocatalytic properties of the BiOBr photocatalyst with different morphologies were investigated through the photodegradation of rhodamine B (RhB). The BiOBr hierarchical micro-flowers synthesized in the solution with the pH 8 show the best photocatalytic activity for wastewater treatment and the ^·O₂⁻ radicals were attributed to be the primary active species for photodegradation of RhB under visible light irradiation.

中文翻译：

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pH值对水热法合成BiOBr的相，形貌和光催化性能的影响

研究了pH对在pH为2-10的溶液中水热合成的BiOBr样品的晶体结构，形态和可见光驱动的光催化的影响。通过X射线衍射，拉曼光谱，傅立叶变换红外光谱，扫描电子显微镜，透射电子显微镜和X射线光电子光谱对合成的BiOBr样品进行了研究。在这项研究中，合成后的样品在2-10的pH值为纯四方BiOBr相，由微板，纳米板和受溶液pH控制的分层微花组成。pH为8的合成样品表明存在Bi 4f，O 1s和Br 3d。通过罗丹明B（RhB）的光降解研究了具有不同形态的BiOBr光催化剂的可见光驱动光催化性能。在pH值为8的溶液中合成的BiOBr分层微花显示出对废水处理的最佳光催化活性。^· ö ₂ ^-基团是由于对可见光照射下罗丹明B光降解的主要活性物质。