Donor-acceptor catalysis with defective MoS₂ and Fe⁰ breaks barriers to perchlorate reduction under mild conditions

Perchlorate (ClO₄^-) contamination in water poses global health risks, yet its efficient reduction to harmless Cl^- under mild conditions remains challenging. Here, we report a donor-acceptor catalytic system comprising defective MoS₂ on N-doped carbon (MoS₂-NC) coupled with zerovalent iron (Fe⁰), which enables rapid ClO₄^- reduction at near-neutral pH (rate constant, 2.36 h^-1), yielding Cl^- as the sole product. In the MoS₂-NC/Fe⁰ system, Fe⁰ acts as the electron donor, while undercoordinated Mo atoms in defective MoS₂ serve as the active sites, and N-doped carbon mediates electron transfer and optimizes the electronic environment for ClO₄^- reduction. The reduction proceeds via oxygen atom transfer, involving Cl-O bond cleavage, O binding to Mo sites, and hydrodeoxygenation of the Mo-bound O atoms. Our observations offer a practical strategy for ClO₄^- reduction without harsh conditions or noble metals and underscore the promise of donor-acceptor-based, defect-engineered catalysts for reductive transformation of challenging oxyanions.