MXenes in PFAS Remediation: Engineered Surfaces and Multifunctional Hybrids

Per- and polyfluoroalkyl substances, commonly referred to as ″forever chemicals″ due to their robust C-F bonds, remain persistent in aquatic environments and resist conventional remediation efforts. This review critically examines current treatment strategies, such as adsorption, membrane filtration, advanced oxidation, reduction, and thermal degradation, highlighting their limitations in terms of energy efficiency, selectivity, and byproduct management. The discussion then focuses on MXenes, a class of two-dimensional transition metal carbides/nitrides known for their high surface area and tunable surface terminations (-OH, -O, -F). Despite their promise, MXenes face challenges, such as aqueous instability and limited reusability. A systematic evaluation is provided on how surface functionalization, through amination, carboxylation, and surfactant modification, enhances PFAS adsorption, particularly for difficult-to-remove short-chain variants. Integration with covalent organic frameworks, metal-organic frameworks, and metal oxides boosts catalytic degradation under ambient conditions. Importantly, this review introduces two innovative strategies: (1) a MXene-microbial fuel cell hybrid that enables in situ regeneration and bioelectrochemical degradation of PFAS and (2) a chemically staged MXene surface with spatially distinct domains that promote sequential PFBS fragmentation without external reagents. These approaches offer scalable, low-energy alternatives that address the critical shortcomings of conventional methods. By tackling persistent issues such as short-chain PFAS degradation, byproduct toxicity, and material recyclability, this review positions MXenes as a multifunctional platform integrating adsorption and catalysis. Our findings pave the way for scalable, next-generation MXene-based materials tailored for sustainable PFAS remediation.