Nano‑Confinement Engineering in 3D Poly(aniline) Networks via BH–NO ₂ Polycondensation for Ultimate Mercury Capture

Mercury remediation requires adsorbents with strong affinity, selectivity, and chemical stability. Here, Pd‐catalyzed Buchwald–Hartwig amination of nitroarenes (BH–NO 2 ) was extended to polycondensation, producing a nitrogen‐rich, three‐dimensional crosslinked poly(aniline)‐like network (PN‐PTA). PN‐PTA achieved a distribution coefficient of 2.1 × 10 8 mL g −1 and >99.9% Hg 2+ removal within 10 min. It maintained effective adsorption across pH 1–12, resisted competing ions and harsh chemical conditions, and enabled fixed‐bed purification to sub‐ppb levels. Spectroscopic analyses and DFT calculations indicate that N–Hg coordination provides the primary binding interaction, while the confined polymer environment further stabilizes Hg 2+ . PN‐PTA retained 89.3% removal efficiency after 25 adsorption–desorption cycles. These results demonstrate BH–NO 2 polycondensation as a useful route to nitrogen‐rich polymer networks for Hg 2+ removal from complex water matrices.