Crystalline Supramolecular Naphthalimide Photocatalyst for Visible-Light Microplastic Mineralization via Enhanced Interfacial Interactions

Abstract

Microplastics accumulate widely in aquatic systems, posing ecological risks. Thus, they require mineralization to inorganic products, yet this is slow under natural sunlight. We present a crystalline naphthalimide supramolecular assembly (NDINH) that promotes photocatalytic mineralization by tuning weak interfacial forces. NDINH forms synergistic π–π contacts and N─H···N≡C hydrogen bonds with polymer surfaces, with adsorption energy 0.327 eV, 2–3.5 times higher than inorganic photocatalysts. This pre-concentration enhances interfacial transport to accelerate mineralization. Under AM1.5G, NDINH removes 92.2% acrylonitrile-butadiene-styrene terpolymer (ABS) in 12 h, k = 0.078 h−1, over 400-fold faster than natural photoaging, with >85% mineralization. Multi-scale mechanism studies indicate an early ·OH-dominated attack that depolymerizes polymers, followed by hhole-drivenoxidation to inorganic species. NDINH degrades polyethylene terephthalate (PET), polycarbonate (PC) and polystyrene (PS) in seawater, river and tap water, and retains activity through a self-healing supramolecular network. The interfacial strategy connects supramolecular design to principles for solid-solid catalysis materials and outlines scalable paths to microplastic degradation.