Integrated Photocatalytic Reduction and Oxidation of Perfluorooctanoic Acid by Metal–Organic Frameworks: Key Insights into the Degradation Mechanisms,Journal of the American Chemical Society

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Integrated Photocatalytic Reduction and Oxidation of Perfluorooctanoic Acid by Metal–Organic Frameworks: Key Insights into the Degradation Mechanisms
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2022-06-22 , DOI: 10.1021/jacs.2c04341
Yinghao Wen ₁ , Ángel Rentería-Gómez ₂ , Gregory S Day ₃ , Mallory F Smith ₂ , Tian-Hao Yan ₂ , Ray Osman K Ozdemir ₃ , Osvaldo Gutierrez ₂ , Virender K Sharma ₄ , Xingmao Ma ₁ , Hong-Cai Zhou _{2,

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Affiliation

The high porosity and tunability of metal–organic frameworks (MOFs) have made them an appealing group of materials for environmental applications. However, their potential in the photocatalytic degradation of per- and polyfluoroalkyl substances (PFAS) has been rarely investigated. Hereby, we demonstrate that over 98.9% of perfluorooctanoic acid (PFOA) was degraded by MIL-125-NH₂, a titanium-based MOF, in 24 h under Hg-lamp irradiation. The MOF maintained its structural integrity and porosity after three cycles, as indicated by its crystal structure, surface area, and pore size distribution. Based on the experimental results and density functional theory (DFT) calculations, a detailed reaction mechanism of the chain-shortening and H/F exchange pathways in hydrated electron (e_aq^–)-induced PFOA degradation were revealed. Significantly, we proposed that the coordinated contribution of e_aq^– and hydroxyl radical (^•OH) is vital for chain-shortening, highlighting the importance of an integrated system capable of both reduction and oxidation for efficient PFAS degradation in water. Our results shed light on the development of effective and sustainable technologies for PFAS breakdown in the environment.

中文翻译：

金属-有机框架对全氟辛酸的综合光催化还原和氧化：降解机制的关键见解

金属有机框架 (MOF) 的高孔隙率和可调性使其成为环境应用中极具吸引力的一类材料。然而，它们在全氟和多氟烷基物质（PFAS）的光催化降解中的潜力很少被研究。因此，我们证明了在汞灯照射下 24 小时内，超过 98.9% 的全氟辛酸 (PFOA) 被钛基 MOF MIL-125-NH _2降解。MOF 在三个循环后保持其结构完整性和孔隙率，如其晶体结构、表面积和孔径分布所示。基于实验结果和密度泛函理论 (DFT) 计算，水合电子 ( e _{aq ) 中的链缩短和 H/F 交换途径的详细反应机理}^– ) 引起的 PFOA 降解已被发现。重要的是，我们提出e _aq和羟基自由基 (^•^{OH) 的协同}作用对于链缩短至关重要，强调了能够还原和氧化的集成系统对于水中 PFAS 的有效降解的重要性。我们的研究结果为开发有效和可持续的 PFAS 在环境中分解的技术提供了启示。

更新日期：2022-06-22

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