The spatially separated active sites for holes and electrons boost the radicals generation for toluene degradation

Hong Wang; Qin Ren; Lei Xiao; Lvcun Chen; Ye He; Lin Yang; Yanjuan Sun; Fan Dong

doi:10.1016/j.jhazmat.2022.129329

The spatially separated active sites for holes and electrons boost the radicals generation for toluene degradation

J Hazard Mater. 2022 Sep 5:437:129329. doi: 10.1016/j.jhazmat.2022.129329. Epub 2022 Jun 13.

Authors

Hong Wang¹, Qin Ren¹, Lei Xiao¹, Lvcun Chen², Ye He¹, Lin Yang³, Yanjuan Sun⁴, Fan Dong⁵

Affiliations

¹ Research Center for Environmental and Energy Catalysis, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China.
² Research Center for Environmental and Energy Catalysis, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China; Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313000, China.
³ Chongqing Key Laboratory of Catalysis and New Environmental Materials, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 400067, China.
⁴ Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313000, China.
⁵ Research Center for Environmental and Energy Catalysis, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, China; Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313000, China. Electronic address: dongfan@uestc.edu.cn.

PMID: 35716569
DOI: 10.1016/j.jhazmat.2022.129329

Abstract

Hydroxyl (⸱OH) and superoxide (⸱O₂^-) radicals are the main drivers for photocatalysis in toluene degradation, but their generation mechanisms are still ambiguous due to the lack of direct evidence. The spatially separated active sites for holes and electrons can help to clarify the dynamic process of radicals generation. By performing theoretical calculations, it is demonstrated that the spatially separated active sites for holes and electrons on the Bi₂O₂CO₃ surface can be constructed by introducing oxygen vacancies in the [Bi₂O₂]²⁺ layer. H₂O and O₂ molecules can be better adsorbed and activated at hole and electron active sites, separately. Accordingly, the pristine and defective Bi₂O₂CO₃ are prepared. The dynamic behavior of H₂O and O₂ molecules at the matching active sites is revealed, which indicates the efficient adsorption of reactants and the substantial production of radicals. Significantly, the specificity of the spatially separated holes and electrons active sites for ⸱OH and ⸱O₂^- radicals generation, respectively, is demonstrated by in situ EPR with the H₂O vapor atmosphere. This work provides a design concept for unraveling reaction mechanisms to realize controllable radicals generation.

Keywords: Active sites; Oxygen vacancy; Photocatalysis; ROS generation; VOCs.