Unlocking electron transfer across carbon overlayers via single-atom engineered built-in electric field for industrial water purification

Abstract Precisely regulating active-sites structures and charge transfer kinetics is crucial for developing high-performance catalysts, yet achieving their synergy remains challenging. Herein, we anchor atomically dispersed cobalt electronic coupling nodes into ultrathin N-doped carbon overlayers (4–5 atomic layers thick) with metallic nanoparticles inside (M@Co1, M = Co2P, Co, Ni or Cu). As revealed by characterization and theoretical calculations, the isolated Co sites mediate interlayer electron transfer between the confined nanoparticles and outermost catalytic interfaces. The extended d-orbital states of single-cobalt atoms establish a built-in electric field and enable work-function matching in hybrid nanostructures. Efficient electron mobility facilitates product desorption and decreases the charge-transfer resistance toward reactants to 19.8% of that in the Co₁-deficient counterpart. Accordingly, Co2P@Co1 exhibits excellent industrial water purification ability via peroxymonosulfate activation, achieving ≥99% phenol removal in 90 s at a low catalyst dosage. It also shows environmental tolerance in real matrices, such as residual organic solvents and inorganic ions.