BiOBr/Bi2MoO6异质结的构筑及对甲基橙的吸附/光催化性能的协同作用机制

采用简单的沉积-沉淀法合成了BiOBr/Bi_2MoO_6(BOB/BMO)异质结,采用XRD、XPS、TEM、SEM、EDS、FT-IR、UV-Vis-DRS、PL、PC和EIS等测试技术对光催化剂的物相组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物甲基橙(MO)的吸附和光催化降解作为探针来评价BiOBr/Bi_2MoO_6异质结的吸附性能与光催化活性增强机制.SEM和TEM分析结果表明,所得Bi_2MoO_6微球由大量厚度约为20~50 nm的纳米片组成;沉淀-沉积法所得样品的形貌分析显示,尺寸约为10 nm的BiOBr量子点均匀沉积在Bi_2MoO_6微球表面,形成的新颖的BOB/BMO异质结.N2吸附/脱附结果表明,Bi_2MoO_6和BiOBr形成异质结具有大的比表面积(64.94 m2·g-1),且表面孔结构丰富.吸附/光催化降解实验结果表明,与纯Bi_2MoO_6或者BiOBr相比,BOB/BMO异质结表现出更好的吸附性能和光催化活性.吸附/光催化协同作用机理分析表明,BOB/BMO异质结具有大的比表面积和丰富的孔结构是其吸附性能增强的主要原因.此外,光致发光(PL)谱、光电流(PC)和交流阻抗(EIS)分析进一步揭示了BOB/BMO异质结有利于光生载流子的分离与转移,导致光催化活性增强,二者的协同作用使其对MO具有优越的去除性能.此外,BOB/BMO异质结较稳定,重复使用性能良好,有望用于MO废水的实际处理.

The fabrication of BiOBr/Bi2MoO6 heterojunction with enhanced adsorption performance for methyl-orange via synergistic adsorption/photocatalysis effect

BiOBr/Bi₂MoO₆(BOB/BMO) heterojunction was successfully fabricated via a facile deposition-precipitation method. Multiple techniques, such as XRD, XPS, TEM, SEM, EDS, FT-IR, UV-Vis-DRS, PL, PC and EIS were applied to investigate the structures, morphology and photocatalytic properties of as-synthesized samples. The adsorption/photocatalytic degradation of methyl-orange(MO) was selected as probe to evaluate the enhanced adsorption/photocatalytic activity of the as-synthesized BiOBr/Bi₂MoO₆. SEM and TEM images show that Bi₂MoO₆ exhibited a three-dimensional spherical structure, which were composed of nanoplates with the thickness of 20~50 nm. The morphology of BiOBr/Bi₂MoO₆ sample revealed that BiOBr quantum dots(QDs) with the size of about 10 nm was well-dispersed on the surface of Bi₂MoO₆ micosphere, resulting in the formation of novel BiOBr/Bi₂MoO₆ heterostructures.N₂ adsorption/desorption results indicate that BiOBr/Bi₂MoO₆ heterostructures possess high abundant pore structure with high specific surface area (S_BET,64.94 m²·g^-1). Adsorption/photocatalytic degradation experiment results indicate that BiOBr/Bi₂MoO₆ heterostructures exhibits much better absorption and visible-light-responsive photocatalytic performance for MO than that of pure BiOBr and Bi₂MoO₆, attributed to the abundant pore structure of BiOBr/Bi₂MoO₆. The synergistic adsorption/photocatalysis effect revealed that high specific surface area (S_BET, 64.94 m²·g^-1) and with abundant pore structure are responsible for excellent adsorption and BOB/BMO heterojunction. In addition, the results of photoluminescence(PL) spectrum, photocurrent(PC) and electrochemical impedance spectroscopy (EIS) analysis indicate that BOB/BMO heterojunction facilitated electron-hole separation and transfer, which led to the increasing adsorption property and photocatalytic activity. Thereby, the synergistic effect adsorption and photocatalysis endows the BOB/BMO excellent removal efficiency for MO. Furthermore, BOB/BMO heterostructures exhibits the high stability and good performance, which is expected to be used in the real application in dye wastewater treatment.