Issue 7, 2022

Generation of environmentally persistent free radicals on faceted TiO2 in an ambient environment: roles of crystalline surface structures

Abstract

The formation of environmentally persistent free radicals (EPFRs) is usually associated with the valence changes of transition metals. The crystalline structures of metal oxides and the role of degradation byproducts in the formation and stabilization of EPFRs have not been fully addressed. In this study, three types of anatase TiO2 with predominantly exposed {001}, {010}, and {101} facets were prepared as model crystal facet structures. Catechol (CT) was loaded onto the faceted TiO2 at room temperature, and EPFRs were only generated on {010}-TiO2 with valence unchanged. The p–d conjugation between Ti and the O from CT was a prerequisite for EPFR formation, and the presence of high-energy electrons involved in p–d conjugation was essential for EPFR stabilization based on quantum chemical calculations. The higher density of unsaturated titanium atoms and more favorable atomic arrangement for electron transfer are the reasons why only {010}-TiO2 stabilized EPFRs. The stability of EPFRs under light and dark conditions was also investigated. The intermediates from CT formed secondary EPFRs at the early stages of the photocatalytic process. Continuous illumination accelerated intermediate degradation and was accompanied by a decrease in EPFR types. This study provides an in-depth understanding of the crystalline structure and degradation byproducts involved in the formation of EPFRs.

Graphical abstract: Generation of environmentally persistent free radicals on faceted TiO2 in an ambient environment: roles of crystalline surface structures

Supplementary files

Article information

Article type
Paper
Submitted
14 Մրտ 2022
Accepted
05 Հնս 2022
First published
06 Հնս 2022

Environ. Sci.: Nano, 2022,9, 2521-2533

Generation of environmentally persistent free radicals on faceted TiO2 in an ambient environment: roles of crystalline surface structures

D. Lang, F. Jiang, X. Gao, P. Yi, Y. Liu, H. Li, Q. Chen, B. Pan and B. Xing, Environ. Sci.: Nano, 2022, 9, 2521 DOI: 10.1039/D2EN00240J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements