Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways

Abstract The increasing global demand for environmental remediation strategies has led to significant interest in the development of efficient photocatalysts. Semiconductor photocatalysts, such as titanium dioxide (TiO₂ P25), have been extensively studied for addressing challenges such as water puri...

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Main Authors: Andrea Martinez-Topete, Eva Jimenez-Relinque, Frederic Dappozze, Sofia Salli, Aziz Genç, Thomas Slater, Chantal Guillard, Andrea Folli, Marta Castellote
Format: Article
Language:English
Published: SpringerOpen 2025-03-01
Series:Journal of Materials Science: Materials in Engineering
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Online Access:https://doi.org/10.1186/s40712-025-00251-6
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author Andrea Martinez-Topete
Eva Jimenez-Relinque
Frederic Dappozze
Sofia Salli
Aziz Genç
Thomas Slater
Chantal Guillard
Andrea Folli
Marta Castellote
author_facet Andrea Martinez-Topete
Eva Jimenez-Relinque
Frederic Dappozze
Sofia Salli
Aziz Genç
Thomas Slater
Chantal Guillard
Andrea Folli
Marta Castellote
author_sort Andrea Martinez-Topete
collection DOAJ
description Abstract The increasing global demand for environmental remediation strategies has led to significant interest in the development of efficient photocatalysts. Semiconductor photocatalysts, such as titanium dioxide (TiO₂ P25), have been extensively studied for addressing challenges such as water purification and air decontamination. However, TiO₂ P25’s wide band gap restricts its efficacy under visible light, which limits its practical use in real-life applications. Bismuth oxyiodides have emerged as highly promising alternatives due to their narrow band gaps and visible-light responsiveness. In this study, BiOI, Bi5O7I, and BiOI/Bi5O7I have been synthesized by pH-dependent co-precipitation and hydrothermal methods and evaluated their photocatalytic performance for phenol degradation and nitrogen oxides (NOx) oxidation. Under visible light irradiation, BiOI-co pH 10 and BiOI/Bi5O7I-co pH 12 demonstrated promising phenol degradation rates (≈51%) compared to the TiO2 P25 benchmark (≈ 11%). In terms of mineralization efficiency, as measured by the total organic carbon (TOC)/phenol ratio (0.6–0.7), Bi5O7I-UV, BiOI/Bi5O7I-VIS, and TiO2 P25-UV showed similar capabilities. Only under UV light irradiation did TiO2 P25 (phenol removal≈100%; NO removal≈86%) surpass the bismuth oxyiodides. Despite showing minimal production of aromatic by-products (e.g., hydroquinone, benzoquinone, and catechol) during phenol degradation, the bismuth oxyiodides exhibited higher NO2 production compared to TiO2 P25 during NOx oxidation. One possible explanation for this phenomenon may be attributed to different ROS-mediated mechanisms present in TiO2 P25 and bismuth oxyiodide compounds. However, the possibility of significant adsorption of intermediates in solution onto bismuth oxyiodide materials cannot be neglected. Quencher experiments, electron paramagnetic resonance (EPR), and terephthalic acid-fluorescence probe method revealed that hydroxyl radicals (HO·) are not the major oxidant specie in in bismuth oxyiodide-mediated photocatalysis. Using evidence from EPR spectroscopy, a photodegradation pathway, involving singlet oxygen (1O2), was proposed. These findings provide valuable insights into the photocatalytic behavior of bismuth oxyiodides and highlights the importance of understanding the mechanisms to optimize their use for environmental applications.
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spelling doaj-art-b7d839dc808f45debd3a5a9c792af5492025-08-20T02:51:24ZengSpringerOpenJournal of Materials Science: Materials in Engineering3004-89582025-03-0120112510.1186/s40712-025-00251-6Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathwaysAndrea Martinez-Topete0Eva Jimenez-Relinque1Frederic Dappozze2Sofia Salli3Aziz Genç4Thomas Slater5Chantal Guillard6Andrea Folli7Marta Castellote8Institute of Construction Science Eduardo Torroja (IETcc-CSIC)Institute of Construction Science Eduardo Torroja (IETcc-CSIC)Institut de Recherches Sur La Catalyse Et L’Environnement de Lyon (IRCELYON), UMR5256, Université Claude Bernard Lyon 1, CNRSSchool of Chemistry, Cardiff UniversitySchool of Chemistry, Cardiff Catalysis Institute, Cardiff UniversitySchool of Chemistry, Cardiff Catalysis Institute, Cardiff UniversityInstitut de Recherches Sur La Catalyse Et L’Environnement de Lyon (IRCELYON), UMR5256, Université Claude Bernard Lyon 1, CNRSSchool of Chemistry, Translational Research Hub, Net Zero Innovation Institute, Cardiff Catalysis Institute, Cardiff UniversityInstitute of Construction Science Eduardo Torroja (IETcc-CSIC)Abstract The increasing global demand for environmental remediation strategies has led to significant interest in the development of efficient photocatalysts. Semiconductor photocatalysts, such as titanium dioxide (TiO₂ P25), have been extensively studied for addressing challenges such as water purification and air decontamination. However, TiO₂ P25’s wide band gap restricts its efficacy under visible light, which limits its practical use in real-life applications. Bismuth oxyiodides have emerged as highly promising alternatives due to their narrow band gaps and visible-light responsiveness. In this study, BiOI, Bi5O7I, and BiOI/Bi5O7I have been synthesized by pH-dependent co-precipitation and hydrothermal methods and evaluated their photocatalytic performance for phenol degradation and nitrogen oxides (NOx) oxidation. Under visible light irradiation, BiOI-co pH 10 and BiOI/Bi5O7I-co pH 12 demonstrated promising phenol degradation rates (≈51%) compared to the TiO2 P25 benchmark (≈ 11%). In terms of mineralization efficiency, as measured by the total organic carbon (TOC)/phenol ratio (0.6–0.7), Bi5O7I-UV, BiOI/Bi5O7I-VIS, and TiO2 P25-UV showed similar capabilities. Only under UV light irradiation did TiO2 P25 (phenol removal≈100%; NO removal≈86%) surpass the bismuth oxyiodides. Despite showing minimal production of aromatic by-products (e.g., hydroquinone, benzoquinone, and catechol) during phenol degradation, the bismuth oxyiodides exhibited higher NO2 production compared to TiO2 P25 during NOx oxidation. One possible explanation for this phenomenon may be attributed to different ROS-mediated mechanisms present in TiO2 P25 and bismuth oxyiodide compounds. However, the possibility of significant adsorption of intermediates in solution onto bismuth oxyiodide materials cannot be neglected. Quencher experiments, electron paramagnetic resonance (EPR), and terephthalic acid-fluorescence probe method revealed that hydroxyl radicals (HO·) are not the major oxidant specie in in bismuth oxyiodide-mediated photocatalysis. Using evidence from EPR spectroscopy, a photodegradation pathway, involving singlet oxygen (1O2), was proposed. These findings provide valuable insights into the photocatalytic behavior of bismuth oxyiodides and highlights the importance of understanding the mechanisms to optimize their use for environmental applications.https://doi.org/10.1186/s40712-025-00251-6Bismuth oxyiodidesPhotocatalysisNOxPhenolBy-productsROS-mediated mechanism
spellingShingle Andrea Martinez-Topete
Eva Jimenez-Relinque
Frederic Dappozze
Sofia Salli
Aziz Genç
Thomas Slater
Chantal Guillard
Andrea Folli
Marta Castellote
Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
Journal of Materials Science: Materials in Engineering
Bismuth oxyiodides
Photocatalysis
NOx
Phenol
By-products
ROS-mediated mechanism
title Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
title_full Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
title_fullStr Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
title_full_unstemmed Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
title_short Bismuth oxyiodides: photocatalytic performance, by-products, and degradation pathways
title_sort bismuth oxyiodides photocatalytic performance by products and degradation pathways
topic Bismuth oxyiodides
Photocatalysis
NOx
Phenol
By-products
ROS-mediated mechanism
url https://doi.org/10.1186/s40712-025-00251-6
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