Photocatalytic reactive oxygen species generation activity of TiO2 improved by the modification of persistent free radicals

Jianli Liu; Guohui Dong; Jun Jing; Shuyun Zhang; Yu Huang; Wingkei Ho

doi:10.1039/D1EN00832C

Photocatalytic reactive oxygen species generation activity of TiO₂ improved by the modification of persistent free radicals†

Jianli Liu,^a Guohui Dong,

*^a Jun Jing,^a Shuyun Zhang,^a Yu Huang

^b and Wingkei Ho

Author affiliations

* Corresponding authors

^a School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China
E-mail: dongguohui@sust.edu.cn

^b Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China

^c Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Tai Po, N.T. Hong Kong, PR China

Abstract

Environmentally persistent free radicals (EPFRs) may help mineral dust to produce more reactive oxygen species (ROS). However, the mechanism of this effect is not yet clear. Therefore, in this study, anatase modified with EPFRs was synthesized via a simple two-step method. The presence of EPFRs was confirmed using a series of characterization techniques, including electron paramagnetic resonance and nuclear magnetic resonance. Herein, we found that EPFRs can improve ˙OH generation via the oxidation reaction between photogenerated holes (h⁺) and OH⁻ (or H₂O). This result was due to two reasons. The first is that the EPFRs construct a built-in electric field, which helps the migration of h⁺ from the bulk to the surface of anatase and then to EPFRs. The other reason is that EPFRs help anatase adsorb more H₂O molecules, which are then oxidized to ˙OH by h⁺. This study will help to understand the photochemical production mechanism of ROS on the surface of mineral dust.

This article is part of the themed collection: Nanomaterials in air

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Article information

DOI: https://doi.org/10.1039/D1EN00832C
Article type: Paper
Submitted: 07 Sep 2021
Accepted: 05 Nov 2021
First published: 08 Nov 2021

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Environ. Sci.: Nano, 2021,8, 3846-3854

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Photocatalytic reactive oxygen species generation activity of TiO₂ improved by the modification of persistent free radicals

J. Liu, G. Dong, J. Jing, S. Zhang, Y. Huang and W. Ho, Environ. Sci.: Nano, 2021, 8, 3846 DOI: 10.1039/D1EN00832C

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Environmental Science: Nano