ERASE-PFAS: Collaborative Research: Nickel and Palladium Single-Atom Electrocatalysts for Selective Capture and Destruction of PFAS in Complex Water Matrices

全氟和多氟烷基物质（PFAS）是一组已被广泛使用了几十年的化学品。作为众多消费品的添加剂，PFAS具有许多理想的性能，包括卓越的耐化学性。然而，这种特性使得它们很难用现有的处理工艺从水中去除。化学稳定性也使PFAS在环境中持续存在，对人类健康和生态健康造成重大关注。电化学氧化是处理水中PFAS为良性终产物的一种很有前途的方法。科学家和工程师们一直在探索各种提高性能的策略，包括使用纳米技术催化剂。然而，这种方法通常需要昂贵的金属，并且在含有各种其他有机化合物的水中选择性地破坏PFAS一直具有挑战性。提出的研究通过开发下一代催化剂来解决这些缺点，这种催化剂可以选择性地结合并破坏PFAS，即使水中含有许多其他化合物。这一目标将通过操纵钯（Pd）和镍（Ni）催化剂的原子分散来实现，这一过程被称为“单原子催化”（SAC）。SAC是缩小材料尺寸的理论极限，代表了纳米技术之外的科学进步。该研究项目的成果将包括开发一个实验室规模的SAC电化学反应器原型，用PFAS污染的水进行测试。研究结果将通过报告、科学期刊、会议和讲座传播。该项目将培养两所大学的研究生和本科生在高度协作的环境下进行跨学科研究。高中生将通过暑期研究实习和拓展课程招募，提高科学素养，发展美国的STEM劳动力。拟议项目的总体目标是开发一种创新的电催化过程，可以氧化破坏复杂水基质中的PFAS，从而产生良性的最终产物。该项目是首批探索SAC（材料缩小的理论极限）作为目标电催化剂结构以实现高选择性和高效的PFAS阳极破坏的研究之一。本研究的重点是钯和镍催化剂，基于它们在纳米尺度上对PFAS的降解性能。与现有的催化技术相比，SAC结构具有许多优点。SAC允许可调的金属配体相互作用和配位环境，这对于1)金属催化中心与PFAS官能团的选择性结合以及2)PFAS向阳极的直接电子转移至关重要。此外，SAC极低的原材料消耗和低成本的合成过程减轻或可能消除了使用钯等贵金属时的成本问题。最后，SACs可能比金属团簇更稳定，这是反应堆实现的一个重要考虑因素。该研究基于一个基本假设，即SAC结构消除了金属晶体纳米团簇中固有的金属-金属相互作用，从而最大程度地增强了PFAS的降解动力学。这一假设将通过使用最先进的EXASF、XANES、HAADF-STEM和原位FTIR技术对合成材料进行表征来验证。反应产物将使用先进的化学分析技术来识别材料特性和PFAS降解途径。该项目的成功完成将促进对SAC合成、SAC驱动电催化的理解，并建立新的PFAS破坏策略。合作团队由两所院校的两个研究小组组成，并具有互补的专业，将为参与的研究生和本科生提供独特的多学科合作培训机会。将为高中学生和教师开设以氟化学和电化学为重点的暑期课程。项目团队致力于招募代表性不足的学生参加所有外展和培训活动，以使国家的STEM劳动力多样化，并促进包容性的研究和学习文化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Per- and polyfluorinated alkyl substances (PFAS) are a group of chemicals that have been widely used for decades. As additives in numerous consumer products, PFAS have many desirable properties, including exceptional chemical resistance. However, this property makes them very difficult to remove from water using current treatment processes. The chemical stability also makes PFAS persist in the environment, causing significant concerns for human and ecological health. One promising way to treat PFAS in water to benign end products is electrochemical oxidation. Scientists and engineers have been exploring various strategies to enhance performance, including employing nanotechnology enabled catalysts. However, expensive metals are often required in this approach, and selective destruction of PFAS in the water that contains various other organic compounds has been challenging. The proposed research addresses these drawbacks through the development of next-generation catalysts that can selectively bind with and destroy PFAS even when the water contains many other compounds. This goal will be pursued by manipulating palladium (Pd) and nickel (Ni) catalysts to be atomically dispersed, a process known as ‘single-atom catalysis’ (SAC). SAC is the theoretical limit of downsizing materials, and represents the state-of-science advancement beyond nanotechnology. The outcomes of this research project will include development of a laboratory-scale prototype SAC electrochemical reactor tested with PFAS contaminated water. Results will be disseminated through reports, scientific journals, conferences, and lectures. This project will train graduate and undergraduate students at two universities to perform interdisciplinary research under a highly collaborative environment. High school students will be recruited via summer research internship and outreach courses, increasing scientific literacy and developing the Nation’s STEM workforce. The overarching objective of the proposed project is to develop an innovative electrocatalytic process that can oxidatively destroy PFAS in complex water matrices to benign end products. This project is one of the first studies to explore SAC – the theoretical limit of material downsizing – as the target electrocatalyst architecture to achieve highly selective and efficient anodic destruction of PFAS. The focus of this research is on Pd and Ni catalysts based on their proven performance for PFAS degradation at nano-scale. The SAC configuration has numerous advantages over existing catalysis technology. SAC allows tunable metal-ligand interactions and coordination environments that are essential for i) selective binding of the metal catalytic centers to functional groups of PFAS, and ii) direct electron transfer from PFAS to the anode. In addition, extremely low consumption of raw materials and low-cost synthesis procedures for SAC alleviate or possibly eliminate cost concerns when using noble metals like Pd. Finally, SACs are likely much more stable than metallic clusters, an important consideration for reactor implementation. The research is based on the underlying hypothesis that SAC architecture eliminates metal-metal interactions that are inherent in metallic, crystalline nanoclusters, resulting in PFAS degradation kinetics enhanced to the maximum extent possible. This hypothesis will be tested through characterization of the synthesized materials using state-of-the-science EXASF, XANES, HAADF-STEM, and in-situ FTIR techniques. Reaction products will be identified using advanced chemical analytical techniques to correlate material property and PFAS degradation pathways. The successful completion of this project will advance understanding of SAC synthesis, SAC-driven electrocatalysis, and establish new strategies for PFAS destruction. The collaborative team consisting of two research groups at two institutions with complimentary specialties will provide unique multidisciplinary, collaborative training opportunities to participating graduate and undergraduate students. Summer courses focusing on fluorine chemistry and electrochemistry will be developed for high school students and teachers. The project team is committed to recruiting underrepresented students for all outreach and training activities to diversify the Nation’s STEM workforce and promote an inclusive culture for research and learning.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.