Cucurbit[8]uril as a supramolecular lock for designing a dual-chain conjugated polymer photocatalyst for enhanced H2O2 production

Abstract

Conjugated polymers (CPs) have garnered attention for their tailorable structural properties, particularly in the context of efficient photosynthetic hydrogen peroxide (H₂O₂) production. However, the challenge lies in the precise molecular engineering of CPs to facilitate different reaction pathways, thereby enhancing the H₂O₂ photogeneration efficiency. In this study, we developed dual-chain CPs (DC-CPs) with a distinctive architecture, employing the supramolecular host cucurbit[8]uril as a “molecular lock” to conjoin two polymer chains. The dual-chain configuration is designed to harbour a central reaction centre conducive to oxygen reduction, providing dual conduction pathways for reactant molecules. The existence of this central reaction center was confirmed through in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy measurements and density functional theory (DFT) calculations. In addition, femtosecond transient absorption spectroscopy (fs-TAS), variable temperature fluorescence spectroscopy and time-resolved photoluminescence (TRPL) measurements reveal double-stranded structures favourable for carrier transport and reactive site activation between dual polymer chains. Ultimately, DC-CPs demonstrate up to a threefold increase in H₂O₂ production compared to their respective single-chain CPs (SC-CPs). This work contributes significantly to the application of CPs for efficient H₂O₂ photogeneration through a molecular engineering strategy.