Department of Chemical & Environmental Engineering, Materials Science & Engineering Program, Department of Chemistry, and Department of Physics & Astronomy, University of California Riverside, Riverside, CA 92521, USA; Department of Chemistry and Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras, Chennai 600036, India.
Department of Chemical & Environmental Engineering, Materials Science & Engineering Program, Department of Chemistry, and Department of Physics & Astronomy, University of California Riverside, Riverside, CA 92521, USA.
J Hazard Mater. 2022 Feb 5;423(Pt A):127026. doi: 10.1016/j.jhazmat.2021.127026. Epub 2021 Aug 25.
Per- and polyfluoroalkyl substances (PFASs) are hazardous, carcinogenic, and bioaccumulative contaminants found in drinking water sources. To mitigate and remove these persistent pollutants, recent experimental efforts have focused on photo-induced processes to accelerate their degradation; however, the mechanistic details of these promising degradation processes remain unclear. To shed crucial insight on these electronic-excited state processes, we present the first study of photo-induced degradation of explicitly-solvated PFASs using excited-state, real-time time-dependent density functional theory (RT-TDDFT) calculations. Furthermore, our large-scale RT-TDDFT calculations show that these photo-induced excitations can be highly selective by enabling a charge-transfer process that only dissociates the CF bond while keeping the surrounding water molecules intact. Collectively, the RT-TDDFT techniques used in this work (1) enable a new capability for probing photo-induced mechanisms that cannot be gleaned from conventional ground-state DFT calculations and (2) provide a rationale for understanding ongoing experiments that are actively exploring photo-induced degradation of PFASs and other environmental contaminants.
全氟和多氟烷基物质（PFASs）是在饮用水源中发现的危险、致癌和生物累积污染物。为了减轻和去除这些持久性污染物，最近的实验研究集中在光诱导过程以加速它们的降解；然而，这些有前途的降解过程的机制细节仍不清楚。为了深入了解这些电子激发态过程，我们使用激发态实时时间依赖密度泛函理论（RT-TDDFT）计算，首次研究了明确溶剂化的 PFASs 的光诱导降解。此外，我们的大规模 RT-TDDFT 计算表明，这些光致激发可以通过使 CF 键发生电荷转移过程而具有高度选择性，同时保持周围水分子完整。总之，本工作中使用的 RT-TDDFT 技术（1）使探测光致机制的新能力成为可能，而这些机制无法从传统的基态 DFT 计算中获得；（2）为理解正在进行的实验提供了依据，这些实验正在积极探索 PFASs 和其他环境污染物的光诱导降解。
