Vacancy Engineered Zero-Valent Iron Steer Hydrogen Spillover toward Per- and Polychlorinated Organics Rapid Complete Dechlorination

The elevated toxicity and persistent bioaccumulative propensity of per- and polychlorinated organics (PCOs) pose a substantial environmental hazard; however, current dechlorination technologies encounter challenges in surmounting the cumulative reductive inertia inherent to PCOs, resulting in low dechlorination efficiency and the persistence of ecotoxicity. Here, a vacancy-engineered zero-valent iron (ZVI) is proposed to address this challenge. The surface-modified carbon vacancies can extract outward-flowing electrons from lattice copper-doped ZVI (CvCu-ZVI), which react with trapped protons to generate reactive hydrogen in situ that subsequently spills over onto ZVI. Reversible hydrogen spillover enhances electron transfer, and superhydrophobic modification leads to a 38.1-fold increase in unit site activity and up to 95% electron utilization in CvCu-ZVI. Excitingly, this approach achieves carbon tetrachloride complete dechlorination, a typical PCOs, with a record intrinsic activity of 13.7 h⁻¹, outperforming state-of-the-art ZVI-based reductants. Theoretical calculations reveal that modulated hydrogen spillover substantially reduces the dechlorination energy barrier of low-chlorinated intermediates, facilitating C─Cl bond dissociation. Furthermore, this novel ZVI has a lower production cost and environmental impact, and can be integrated into permeable reaction units for long-term efficient organohalogen pollution remediation in natural groundwater. This broadly applicable approach establishes a promising paradigm for the sustainable remediation of PCOs pollution.