Promoting Solar-driven Hydrogen Peroxide Production over Thiazole-based Conjugated Polymers via Generating and Converting Singlet Oxygen

Abstract

Solar-driven synthesis of hydrogen peroxide (H₂ O₂ ) from water and air provides a low-cost and eco-friendly alternative route to the traditional anthraquinone method. Herein, four thiazole-based conjugated polymers (Tz-CPs: TTz, BTz, TBTz and BBTz) are synthesized via aldimine condensation. BBTz exhibits the highest H₂ O₂ production rate of 7274 μmol g^-1 h^-1 in pure water. Further, the reaction path is analyzed by electron paramagnetic resonance (EPR), in situ diffuse reflectance infrared Fourier transform (DRIFT) and theoretical calculation, highlighting the prominent role of singlet oxygen (¹ O₂ ). The generation of ¹ O₂ occurs through the oxidation of superoxide radical (⋅O₂ ^- ) and subsequent conversion into endoperoxides via [4+2] cycloaddition over BBTz, which promotes charge separation and reduces the barrier for H₂ O₂ production. This work provides new insight into the mechanism of photocatalytic O₂ reduction and the molecular design of superior single-polymer photocatalysts.

Keywords: 1O2; H2O2; Reaction Path; Thiazole-Based Conjugated Polymers; [4+2] Cycloaddition.