Bi2O3-Bi2WO6 直接Z-scheme异质结的制备、表征及光催化还原U(VI)的性能

根据能带理论，以Bi(NO₃)₃·5H₂O为铋源，采用水热煅烧法制备了Bi₂O₃-Bi₂WO₆复合光催化材料，SEM、XRD、XPS、紫外可见漫反射(UV-vis DRS)、电化学阻抗(EIS)等表征手段对材料进行表征与分析，以U(VI)为目标污染物，在可见光下进行光催化还原U(VI)的性能研究。结果表明:与纯Bi₂WO₆相比，Bi₂O₃-Bi₂WO₆复合材料具有较高的光催化活性，当Bi₂O₃与Bi₂WO₆的摩尔比为2.4∶1时，Bi₂O₃-Bi₂WO₆的光催化活性最好，光催化活性增强归因于Bi₂O₃的加入，在Bi₂O₃与Bi₂WO₆界面形成的直接Z-scheme异质结，提高了光生电子-空穴的传输速率，降低了其复合率；另一方面，Bi₂O₃的加入使Bi₂WO₆带隙变小，扩大对可见光的响应范围，从而提高了Bi₂O₃-Bi₂WO₆光催化剂的活性。本研究为设计和合成具有高可见光活性的光催化剂和了解增强U(VI)光催化还原机理提供了新的思路。 

Preparation and characterization of Bi2O3-Bi2WO6 direct Z-scheme heterojunction and photocatalytic reduction of U(VI) under visible light irradiation

According to the energy band theory, Bi(NO₃)₃·5H₂O was used as bismuth source to synthesize Bi₂O₃-Bi₂WO₆ composite photocatalyst materials by hydrothermal calcination. The samples were characterized by means of SEM, XRD, XPS, DRS and EIS, respectively, and the photocatalytic activity was assessed in terms of reduction of U(VI) under visible light irradiation. The results show that the prepared Bi₂O₃-Bi₂WO₆ composite materials exhibit enhanced photocatalytic performance for the photo-reduction of U(VI) than the pure Bi₂WO₆, the optimized photocatalytic efficiency for U(VI) is achieved when the mole ratios of Bi₂O₃ to Bi₂WO₆ is 2.4∶1. The improved photocatalytic activity is ascribed to the direct Z-scheme heterojunction between Bi₂O₃ and Bi₂WO₆, resulting in the rapid interfacial transfer of photoelectron-hole and wide light response range. This work provides a new idea to design and synthesize the photocatalysts with high visible light activity and understand the enhanced photocatalytic reduction mechanism of U(VI).