Insights into Photothermally Enhanced Photocatalytic U(VI) Extraction by a Step-Scheme Heterojunction

Yifeng Zhang; Haorong Sun; Feixue Gao; Shuo Zhang; Qingzhi Han; Jing Li; Ming Fang; Yawen Cai; Baowei Hu; Xiaoli Tan; Xiangke Wang

doi:10.34133/2022/9790320

Insights into Photothermally Enhanced Photocatalytic U(VI) Extraction by a Step-Scheme Heterojunction

Research (Wash D C). 2022 Oct 11:2022:9790320. doi: 10.34133/2022/9790320. eCollection 2022.

Authors

Yifeng Zhang¹, Haorong Sun¹, Feixue Gao¹, Shuo Zhang¹, Qingzhi Han², Jing Li³, Ming Fang¹, Yawen Cai⁴, Baowei Hu⁴, Xiaoli Tan¹, Xiangke Wang¹

Affiliations

¹ MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
² Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
³ Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
⁴ School of Life Science, Shaoxing University, Shaoxing 312000, China.

Abstract

In this work, a CdS/BiVO₄ step-scheme (S-scheme) heterojunction with self-photothermally enhanced photocatalytic effect was synthesized and applied for efficient U(VI) photoextraction. Characterizations such as transient absorption spectroscopy and Tafel test together confirmed the formation of S-scheme heterojunctions, which allows CdS/BiVO₄ to avoid photocorrosion while retaining the strong reducing capacity of CdS and the oxidizing capacity of BiVO₄. Experimental results such as radical quenching experiments and electron spin resonance show that U(VI) is rapidly oxidized by photoholes/^•OH to insoluble UO₂(OH)₂ after being reduced to U(IV) by photoelectrons/^•O₂ ^-, which precisely avoids the depletion of electron sacrificial agents. The rapid recombination of electron-hole pairs triggered by the S-scheme heterojunction is found to release large amounts of heat and accelerate the photocatalysis. This work offers a new enhanced strategy for photocatalytic uranium extraction and presents a direction for the design and development of new photocatalysts.