Toward sustainable PFAS elimination: Engineering TiO2 photocatalysts for complete mineralization and defluorination

The inescapable environmental persistence of perfluoroalkyl substances (PFAS) necessitates the development of advanced destructive technologies for their elimination. One promising approach is the photodegradation technique, which utilizes light energy to generate reactive species that can completely mineralize and defluorinate the PFAS into harmless substances. Accordingly, this comprehensive review critically evaluates the potential and limitations of TiO 2 and its composites as valuable engineering materials for the PFAS degradation. The review focuses on innovative methods for enhancing TiO 2 , such as doping with metals and non-metals, as well as creating heterojunction and composite structures. These modifications aimed at increasing the surface area, reducing the bandgap, improving visible light absorption, enhancing charge separation, and promoting the concentration of PFAS near active sites to facilitate effective degradation. The findings showcase remarkable degradation and defluorination of PFAS due to these enhancements. However, the review also uncovers significant challenges for real-world applications and the potential risk of secondary contamination, highlighting the existence of a critical gap between laboratory efficiency and field practicality. Therefore, while TiO 2 -based photocatalysis holds exceptional promise, its transition to a scalable, sustainable technology requires a research paradigm shift towards eco-design with benign dopants, reactor optimization for real wastewater, and rigorous lifecycle assessments to ensure net environmental benefit, thereby ultimately positioning this technology as a potential foundation for addressing one of today's most pressing environmental challenges.