光催化氧化法是治理大气环境汞污染问题的有效手段。目的目的为开发低成本的可见光脱汞催化剂,方法方法采用一步共沉淀法合成不同溴(Br)含量的BiOBrxCl1−x微球复合材料,在湿法光催化脱汞装置上考察它们在荧光灯辐照下的光催化活性,利用N2吸附-脱附、XRD、UV-VisDRS、SEM、HRTEM、XPS和ESR等技术对其结构进行分析,并采用密度泛函理论研究BiOCl和BiOBr之间的电荷转移规律。结果结果结果表明,相较于BiOCl和BiOBr,BiOBrxCl1−x复合材料的光催化性能均得到提升,其中BiOBr0.2Cl0.8光催化剂的脱汞效率高达90.3%,较BiOCl提高了50%;与NO−3和SO42−相比,Cl−和CO32−对BiOBr0.2Cl0.8光催化剂脱汞性能的抑制作用更显著;BiOBr0.2Cl0.8复合材料的比表面积均略高于BiOBr的和BiOCl的,较高的比表面积有利于光催化剂提供较多的活性位;随着Br含量逐渐增加,BiOCl的XRD特征峰强度逐渐减弱,复合材料的光吸收能力有规律地红移,表明BiOBr与BiOCl之间存在较强的相互作用,并非简单的机械混合;与BiOCl相比,BiOBr0.2Cl0.8复合材料的Bi4f和O1s均向高结合能方向偏移,表明引入Br影响了BiOCl中Bi和O的存在形态;3种活性物参与了Hg0的氧化脱除过程,其作用由大到小依次为•O−2,h+,•OH。结论结论光催化活性的提高主要原因为BiOCl与BiOBr形成了Z型异质结,从而增强了光生电荷的分离。研究结果可为低成本、高效卤氧化铋基脱汞光催化剂的开发提供新思路。

Photocatalytic oxidation is an effective technology to control atmospheric mercury pollution. Objec⁃tives To develop a low-cost visible-light-driven mercury removal catalyst, Methods microspherical BiO‐BrClcomposite photocatalysts with different molar contents of bromine(Br) were synthesized by an one-step coprecipitation method,and their photocatalytic performances of Hg removal under fluorescent lamp(FSL) were implemented in a wet photocatalytic mercury removal device.The physical and chemical struc‐tures of the samples were analyzed by N adsorption-desorption,XRD,UV-Vis DRS,SEM,HRTEM,XPS and ESR. Moreover,the charge transfer between BiOCl and BiOBr was studied using density functional theory. Results The results showed that compared with BiOCl and BiOBr,the photocatalytic performances of BiOBrCl composites were all improved,and the Hg removal efficiency of BiOBrCl photocatalyst reached as high as 90.3%,which was about 50% than that of pure BiOCl.Compared with NO and SO,Cl and CO exhibited significant inhibitions on Hg removal.The specific surface area of BiOBrCl com‐posites was slightly higher than that of BiOBr and BiOCl,which would be beneficial for providing more reac‐tive sites.With the gradual increase of Br content,the XRD characteristic peak intensity of BiOCl gradually decreased,and the photocatalytic absorption capacity appeared redshift regularly,indicating a strong interac‐tion between BiOBr and BiOCl,not a simple mechanical mixing. Both Bi 4f and O 1s of the BiOBrCl composite material were shifted towards higher binding energies,indicating that the introduction of Br af‐fected the species of Bi and O in BiOCl. The mechanism analysis displayed that the three active species were involved in the oxidative process of Hg removal with the high-to-low order of O,h ,OH. Conclu⁃sions The improvement of photocatalytic activity was mainly due to the formation of Z-type heterojunction between BiOCl and BiOBr,which effectively enhanced the separation of photo-generated charges.The study provided a new idea for the development of low-cost and efficient bismuth oxyhalide-based photocatalysts for mercury removal.