A review of photocatalytic decomposition of per- and polyfluoroalkyl substances in aqueous solution

Per- and polyfluoroalkyl substances (PFASs) are a key concern in aqueous environments owing to their persistence, bioaccumulation, and toxicity. Photocatalysis offers several advantages for PFAS removal compared to other treatment processes (e.g., adsorption, ion exchange, membrane filtration, plasma, ozone, and ultrasonication), including potential complete mineralization/defluorination, broad applicability (for both long- and short-chain PFASs), and cost-effective operation with the utilization of visible light. In recent years, research and review publications have been increasing on the photocatalytic degradation of PFASs. This paper provides a complete and systematic review of the most current advances in the photocatalytic removal of PFASs (2020-2025 data), and specifically assesses their photocatalytic properties (structure, band gap energy, light absorption, and surface area), environmental factors (solution pH, background ionic strength, and natural organic matter), and operating conditions (light intensity and wavelength). Overall, the findings suggest that photo-oxidation/reduction with various reactive species (h⁺, e^-, ^•OH, O₂^•-, and SO₄^•-) plays a substantial role in the PFAS degradation activity. However, PFAS degradation efficiency still varies significantly depending on the catalysts, water quality conditions, and/or operating conditions. A brief discussion of future research directions is also provided to address existing knowledge gaps and resolve concerns regarding photocatalysis in real-world applications.