Vacancy-Engineered Single-Atom MXene Membranes: A Quantum Leap in Ultrahigh-Flux Nanoconfinement Catalysis for Robust Water Decontamination

Membrane-based nanoconfinement catalytic oxidation (MNCO) offers promise for degrading persistent organic micropollutants (OMPs) in aqueous environments. Nevertheless, the intrinsic efficiency-flux-stability trade-off impedes its further large-scale engineering implementation. This study addresses this fundamental challenge through a first-of-its-kind tripartite strategy encompassing atomic-scale material design, mechanistic innovation, and structural engineering. A novel Co-N-Ti_3−xC₂T_y membrane is developed through vacancy-mediated atomic trapping, constructing asymmetric Co-N₁C₂ sites on Ti-defective MXene, synergizing hierarchical mass transfer optimization (Knudsen-like flow, expanded external nanopores, minimized transport distance) with the nanoconfinement effect. This achieves an unprecedented high water flux of 2157 LMH, surpassing conventional membranes by 2−3 orders of magnitude, while maintaining 100% removal efficiency for various OMPs within 13.2 ms of retention time. Crucially, nanoconfinement and electronic delocalization at Co-N₁C₂ sites synergistically activate peroxymonosulfate to generate reactive oxygen species and accelerate catalyst-mediated electron transfer, reducing formation energy barriers and diffusion distances, collectively culminating in 10⁵−10⁷-fold reaction kinetic enhancement relative to non-confined analogues. Co single-atom incorporation via Ti vacancies enhances structural integrity, ensuring stability in real water matrices and robustness for >130 h with <3% Co loss. This integrated design overcomes the catalytic membrane trilemma, enabling sustainable ultrafast decontamination and advancing MNCO for high-performance, eco-friendly purification systems toward global water security.