Molecular Exciton Engineering in Thiobarbituric Acid-Based Linear Copolymers for High-Efficiency Photocatalytic Uranium Extraction

Linear copolymers (LPs), due to their fully exposed active sites, show significant potential for visible-light-driven photocatalytic uranium reduction. Arising from Coulomb interactions between electrons and holes, excitonic effects critically influence the photocatalytic performance of LPs. However, this factor has long been overlooked. Herein, three thiobarbituric acid-based LPs (TTP, BTB, and NTN) are fabricated via catalyst-free multicomponent reactions. By systematically substituting the donor units in their skeletons (phenyl, biphenyl, and naphthyl), we precisely tuned their excitonic properties. Experimental and theoretical calculation results demonstrate that stronger donor-acceptor interactions reduce the exciton binding energy (<i>E</i>_b) and amplify dipole moments, thereby accelerating exciton dissociation and charge transfer. Consequently, TTP featuring a phenyl donor demonstrates optimal intramolecular charge transfer, minimum <i>E</i>_b (61.4 meV), and a maximum dipole moment (13.15 D). This results in a uranium extraction capacity of 778.8 mg g^-1 and 99.6% photocatalytic removal efficiency from actual uranium-containing wastewater. Our findings advance molecular exciton control in LPs, paving the way for more efficient photocatalytic treatment of uranium mine wastewater.