Construction of g-C3N4/Ag/TiO2 Z-scheme photocatalyst and Its improved photocatalytic U(VI) reduction application in water

Yuelin Liu; Yilei Yuan; Shangyuan Ni; Jun Liu; Shuibo Xie; Yingjiu Liu

doi:10.2166/wst.2022.139

Construction of g-C₃N₄/Ag/TiO₂ Z-scheme photocatalyst and Its improved photocatalytic U(VI) reduction application in water

Water Sci Technol. 2022 May;85(9):2639-2651. doi: 10.2166/wst.2022.139.

Authors

Yuelin Liu¹, Yilei Yuan², Shangyuan Ni³, Jun Liu⁴, Shuibo Xie⁵, Yingjiu Liu²

Affiliations

¹ Key Discipline Laboratory for National Defence for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; School of Civil Engineering, Hunan University of Technology, Zhuzhou 412007, China.
² Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China E-mail: xiesbmr@263.net.
³ School of Civil Engineering, Hunan University of Technology, Zhuzhou 412007, China.
⁴ Hunan Key Laboratory of Biomedical Nanomaterials and Devices, School of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, China.
⁵ Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China E-mail: xiesbmr@263.net; School of Civil Engineering, University of South China, Hengyang 421001, China.

PMID: 35576258
DOI: 10.2166/wst.2022.139

Abstract

The reduction of soluble U(VI) to insoluble U(IV) by photocatalytic technology is considered to be a valid method to remove U(VI) from water. Herein, g-C₃N₄/Ag/TiO₂ Z-scheme heterojunction was synthesized for photocatalytic U(VI) reduction application. The SEM, XRD and XPS characterization results showed that a ternary g-C₃N₄/Ag/TiO₂ composite photocatalyst was synthesized successfully. g-C₃N_4/Ag/TiO₂ exhibited excellent photocatalytic reduction performance for U(VI) under visible light irradiation. After 30 min irradiation, the removal rate of U(VI) was above 99%. XPS indicated that the majority of U(VI) on the surface of g-C₃N₄/Ag/TiO₂ was reduced to U(IV). In addition, the photocatalytic activity of g-C₃N₄/Ag/TiO₂ has been kept significantly after five rounds of experiments, indicating good stability. g-C₃N₄/Ag/TiO₂ exhibited better photocatalytic reduction of U(VI) under visible light irradiation, which is mainly ascribed to Z-scheme photocatalytic mechanism assisted by the LSPR effect (Local Surface Plasmon Resonance). Ag with plasmon resonance effect on the loading has a strong absorption of photon energy. In addition, an intermediate charge transfer channel is formed between Ag and the semiconductor to inhibit the combination of photogenerated electrons and holes, resulting in a significant increase in the photocatalytic activity of the photocatalyst. This idea has some significance in design of other composite photocatalytic systems.