Photocatalytic Defluorination of Per- and Polyfluoroalkyl Substances: From Mechanistic Insights to Rational Design

Per- and polyfluoroalkyl substances (PFAS) pose severe threats to ecosystems and human health due to their extreme persistence, bioaccumulation, and toxicity. Their ultra-strong C–F bonds render them recalcitrant to conventional water treatment technologies, spurring growing interest in photocatalytic degradation as a promising alternative. This review establishes a photocatalytic PFAS treatment framework that focuses on defluorination. We systematically compare the contributions of various reactive species to PFAS defluorination and evaluate the primary degradation pathways based on their defluorination efficiencies and the toxicities of the resulting intermediates. Furthermore, key influencing factors and integrated design strategies are summarized to enhance defluorination performance. This review provides a roadmap for developing photocatalytic technologies capable of truly destroying per- and polyfluoroalkyl substances.