Novel porphyrin-based donor–acceptor conjugated organic polymers for efficient photocatalytic production of hydrogen peroxide in pure water

Abstract

Artificial photosynthetic production of hydrogen peroxide (H₂O₂) using conjugated organic polymer semiconductor photocatalysts is a promising approach. However, its application is limited mainly by the rapid rate of photogenerated carrier complexation. Here, we have prepared three novel porphyrin-based donor–acceptor conjugated organic polymers using porphyrin as a precursor and benzene–diamine ligands as basic blocks for the photocatalytic and efficient production of H₂O₂ under pure water. Density functional theory (DFT) calculations show that aniline ligands act as electron donors (D) and porphyrins act as electron acceptors (A). The TCFPP-TPD exhibits efficient photocatalytic H₂O₂ production with an initial rate of 1180 μmol g⁻¹ h⁻¹ under visible light (λ > 420 nm) irradiation without any additional sacrificial agents or co-catalysts. By increasing the number of benzene rings, the electron-donating ability of the benzene–diamine ligands was significantly enhanced, improving their electron-donor–acceptor (D–A) interactions with the porphyrins and facilitating the separation of the photogenerated electron–hole pairs. Moreover, the possible process for producing H₂O₂ through TCFPP-TPD photocatalysis was disclosed through in situ FT-IR and electron spin resonance (ESR). This study proposes novel design concepts for the rational construction of D–A structures with the aim of increasing the charge separation efficiency, which is crucial for the effective production of H₂O₂.