Pair‐Resolved Fe–M Dual‐Atom Catalysts for Programmed PMS Activation: Mechanisms, Membrane Confinement, and Standardized Benchmarks

Fe-based dual-atom catalysts (Fe-M DACs) are redefining peroxymonosulfate (PMS) activation by enabling programmable switching between radical and non-radical routes. This Review synthesizes recent progress through a pair-resolved lens (Fe-Co, Fe-Mo, Fe-Fe, Fe-Ni), linking µ-peroxo bridging and spin/electronic coupling to pathway selection, pollutant selectivity, and stability. A co-selection matrix distinguishes literature testing preferences from true performance correlations, while a BPA case study maps metal-dependent route bifurcation (phenoxy-radical/interfacial electron-transfer (ETP) versus hydroxylation-opening-mineralization). Translation to practice is highlighted by membrane-confined systems that couple reaction and separation, maintain flux in saline/organic-rich effluents, and lower toxicity, supported by QSAR predictions and bioassays. Design rules are distilled for antibiotics and other electron-rich targets, and outline standards for reporting conditions, metal leaching, TOC mineralization, and evidence matrices (EPR, isotope/quenching, operando XAS/Raman, DFT). Finally, opportunities are charted for tailored strategies toward halogenated/strongly electron-deficient pollutants and emerging contaminants (PFAS, ARGs, microplastics). Collectively, Fe-M DACs establish an atom-level "catalyst-co-catalyst" paradigm for robust, selective, and safer advanced oxidation in complex waters.