Mitigating polymer-induced self-inhibition with microenvironment-decoupled Sn(II) single-atom catalysts for pollutant polymerization

Selective oxidation-driven pollutant polymerization enables simultaneous contaminant removal and carbon recovery, yet current catalysts suffer from competitive adsorption between pollutants and oxidants, disrupting redox balance and causing premature termination. Herein, we present a microenvironment-decoupled strategy by anchoring atomically dispersed Sn on amino-functionalized carbon nanotubes (CNT−NH 2 ). Amino preferentially stabilizes Sn as Sn(II)−N 4 , which selectively activates peroxydisulfate (PDS) by forming a bidentate Sn–PDS complex and sustains an electron-transfer-dominated pathway. Meanwhile, the carbon surface enriches phenolic substrates and sustains their para -C–O polymerization transfer. In situ spectroscopy and density functional theory identify Sn 5 p –O 2 p interactions as the origin of this unique selectivity. As a result, the SnPc/CNT−NH 2 /PDS system maintains over 95% phenol removal after five cycles (versus one cycle for CNT) and achieves ~82% total organic carbon removal (versus ~46% for CNT). A decoupled reactor further demonstrates the practical feasibility of this mechanism for continuous water purification. This work provides a microenvironment-decoupled paradigm for precise oxidation regulation toward sustainable pollutant polymerization transfer in water purification.