CO₂-Responsive Smart Wood Scaffold for Natural Organic Matter Removal without Secondary Pollution

Ensuring drinking water safety remains a critical challenge, particularly when treating complex water sources, due to secondary pollution caused by active chemical additives. Herein, a novel CO₂-responsive smart wood scaffold that leverages non-toxic CO₂ activation is developed to achieve highly efficient removal of carcinogenic natural organic matter (NOM) and broad-spectrum microbial disinfection without requiring additional chemical agents. Unlike conventional water purification techniques that face a safety-efficacy trade-off, the multi-stage CO₂-responsive wood scaffold offers exceptional tunability in NOM abatement across diverse environmental conditions, including variable water chemistry, NOM composition, high salinity, and real-world water sources. The purified water meets stringent drinking water standards (e.g., UV₂₅₄ reduction, dissolved organic carbon removal, and bacterial elimination). It is found that the highly efficient NOM adsorption mainly originates from the strong and stable CO₂-triggered cation-π interaction between the scaffold surface and aromatic NOM groups, as revealed via high-resolution mass spectrometry and direct intermolecular force measurements. This ecofriendly and contamination-free CO₂-responsive strategy provides a transformative approach to overcoming secondary pollution challenges in water purification, offering a scalable and sustainable platform for environmental applications and beyond.