Electron spin resonance evidence for electro-generated hydroxyl radicals

Electro-generated hydroxyl radicals (•OH) are of fundamental importance to the electrochemical advanced oxidation process (EAOP). Radical-specific electron spin resonance (ESR) evidence is still lacking in association with the direct electron transfer (DET) reaction of spin trap (e.g., 5,5-dimethyl-...

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Main Authors: Pei, Shuzhao, You, Shijie, Ma, Jun, Chen, Xiaodong, Ren, Nanqi
Other Authors: School of Materials Science and Engineering
Format: Article
Language:English
Published: 2021
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Online Access:https://hdl.handle.net/10356/152434
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1524342021-08-24T05:10:28Z Electron spin resonance evidence for electro-generated hydroxyl radicals Pei, Shuzhao You, Shijie Ma, Jun Chen, Xiaodong Ren, Nanqi School of Materials Science and Engineering Innovative Centre for Flexible Devices Engineering::Materials Adducts Electrodes Electro-generated hydroxyl radicals (•OH) are of fundamental importance to the electrochemical advanced oxidation process (EAOP). Radical-specific electron spin resonance (ESR) evidence is still lacking in association with the direct electron transfer (DET) reaction of spin trap (e.g., 5,5-dimethyl-1-pyrroline-N-oxide; DMPO) and side reactions of the DMPO-OH adduct in the strongly oxidative environment offered by anodic polarization. Herein, we showed ESR identification of electro-generated •OH in EAOP based on the principle of kinetic selection. Excessive addition of a DMPO agent and fast spin trapping allowed suitable kinetic conditions to be set for effective spin trapping of electro-generated •OH and subsequent ESR identification. Otherwise, interferential triplet signals would emerge due to formation of paramagnetic dimer via dehydrogenation, DET oxidation, and dimerization reactions of the DMPO-OH adduct. The results demonstrate that •OH formation during spin-trapping on the titanium suboxide (TiSO) anode could be quantified as 47.84 ± 0.44 μM at current density of 10 mA cm-2. This value revealed a positive dependence on electrolysis time, current density, and anode potential. The effectiveness of ESR measurements was verified by the results obtained with the terephthalic acid probe. The ESR identification not only provides direct evidence for electro-generated •OH from a fundamental point of view, but also suggests a strategy to screen effective anode materials. National Research Foundation (NRF) Project supported by the National Natural Science Foundation of China (Grant No. 51822806, 51678184, 51761145031), Singapore National Research Foundation (NRF2017NRFNSFC001-048), Fundamental Research Funds for the Central Universities (Grant No. HIT.BRETIV.201905), and State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology) (No. 2020DX07). 2021-08-24T05:10:28Z 2021-08-24T05:10:28Z 2020 Journal Article Pei, S., You, S., Ma, J., Chen, X. & Ren, N. (2020). Electron spin resonance evidence for electro-generated hydroxyl radicals. Environmental Science and Technology, 54(20), 13333-13343. https://dx.doi.org/10.1021/acs.est.0c05287 0013-936X https://hdl.handle.net/10356/152434 10.1021/acs.est.0c05287 32931260 2-s2.0-85093905659 20 54 13333 13343 en NRF2017NRF-NSFC001-048 Environmental Science and Technology © 2020 American Chemical Society. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Materials
Adducts
Electrodes
spellingShingle Engineering::Materials
Adducts
Electrodes
Pei, Shuzhao
You, Shijie
Ma, Jun
Chen, Xiaodong
Ren, Nanqi
Electron spin resonance evidence for electro-generated hydroxyl radicals
description Electro-generated hydroxyl radicals (•OH) are of fundamental importance to the electrochemical advanced oxidation process (EAOP). Radical-specific electron spin resonance (ESR) evidence is still lacking in association with the direct electron transfer (DET) reaction of spin trap (e.g., 5,5-dimethyl-1-pyrroline-N-oxide; DMPO) and side reactions of the DMPO-OH adduct in the strongly oxidative environment offered by anodic polarization. Herein, we showed ESR identification of electro-generated •OH in EAOP based on the principle of kinetic selection. Excessive addition of a DMPO agent and fast spin trapping allowed suitable kinetic conditions to be set for effective spin trapping of electro-generated •OH and subsequent ESR identification. Otherwise, interferential triplet signals would emerge due to formation of paramagnetic dimer via dehydrogenation, DET oxidation, and dimerization reactions of the DMPO-OH adduct. The results demonstrate that •OH formation during spin-trapping on the titanium suboxide (TiSO) anode could be quantified as 47.84 ± 0.44 μM at current density of 10 mA cm-2. This value revealed a positive dependence on electrolysis time, current density, and anode potential. The effectiveness of ESR measurements was verified by the results obtained with the terephthalic acid probe. The ESR identification not only provides direct evidence for electro-generated •OH from a fundamental point of view, but also suggests a strategy to screen effective anode materials.
author2 School of Materials Science and Engineering
author_facet School of Materials Science and Engineering
Pei, Shuzhao
You, Shijie
Ma, Jun
Chen, Xiaodong
Ren, Nanqi
format Article
author Pei, Shuzhao
You, Shijie
Ma, Jun
Chen, Xiaodong
Ren, Nanqi
author_sort Pei, Shuzhao
title Electron spin resonance evidence for electro-generated hydroxyl radicals
title_short Electron spin resonance evidence for electro-generated hydroxyl radicals
title_full Electron spin resonance evidence for electro-generated hydroxyl radicals
title_fullStr Electron spin resonance evidence for electro-generated hydroxyl radicals
title_full_unstemmed Electron spin resonance evidence for electro-generated hydroxyl radicals
title_sort electron spin resonance evidence for electro-generated hydroxyl radicals
publishDate 2021
url https://hdl.handle.net/10356/152434
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