Z-scheme V2O5-Ag2O/g-C3N4异质结制备及其可见光催化性能

采用原位生长法制备V₂O₅,并将其与Ag₂O/g-C₃N₄水热复合制备V₂O₅-Ag₂O/g-C₃N₄复合光催化剂.利用XRD、FT-IR、SEM和UV-Vis DRS等方法对样品的形貌结构及光学性质进行表征.结果表明,V₂O₅成功掺杂在Ag₂O/g-C₃N₄上,与Ag₂O/g-C₃N₄相比,复合材料对可见光的吸收范围增大;在可见光照射180min后,V₂O₅掺杂量为15%的复合材料对亚甲基蓝(MB)的降解率达到99.10%.经过3次循环降解后,复合材料对MB的降解率保持85%以上,表明其具有良好的稳定性.通过掩蔽实验推测,空穴(h⁺)是光催化体系中主要的活性物质,其光催化性能增强的机理是Ag₂O与g-C₃N₄复合界面形成p-n异质结,并与V₂O₅之间的复合过程符合Z-scheme可见光驱动机制,有效阻碍了光生电子-空穴对的复合,促进活性物质的产生.

Fabrication and visible-light photocatalytic performance of Z-scheme V2O5-Ag2O/g-C3N4 heterostructure

V₂O₅ was prepared by in-situ synthesized method, and then composited with Ag₂O/g-C₃N₄ by hydrothermal method to produce V₂O₅-Ag₂O/g-C₃N₄ photocatalysts. The morphology and optical properties of the as-prepared samples were characterized by XRD, FT-IR, SEM and UV-Vis DRS. The results showed that V₂O₅ was successfully doped on the surface of Ag₂O/g-C₃N₄, and the visible-light absorption range of V₂O₅-Ag₂O/g-C₃N₄ composites were broadened compared to Ag₂O/g-C₃N₄. The degradation efficiency of methylene blue (MB) by 15% V₂O₅-Ag₂O/g-C₃N₄ composites reached 99.10% after 180min of visible-light irradiation. The degradation efficiency of MB was above 85% by the composites after 3cycles of degradation, which revealed that V₂O₅-Ag₂O/g-C₃N₄ composites had excellent stability. The quenching tests of radicals indicated that holes (h⁺) was the main active species during the photocatalytic reaction process. The p-n heterojunction at the interface of Ag₂O and g-C₃N₄ was formed, and the recombination process of Ag₂O and V₂O₅ followed Z-scheme visible-light-driven mechanism, which effectively hindered the recombination of photogenerated electron-hole pairs and promoted the production of active species, thus, enhancing the photocatalytic activity of composites.