Engineering modular and tunable overall photocatalytic generation of H2O2via atomic regulation of 1D covalent organic frameworks

Abstract

The photocatalytic oxygen reduction reaction (ORR) and the water oxidation reaction (WOR) are highly promising green methods for hydrogen peroxide (H₂O₂) production. However, designing efficient photocatalysts for H₂O₂ synthesis remains a significant challenge. In this study, a series of novel one-dimensional covalent organic frameworks (1D COFs) named FZU-301 (–S–), FZU-302 (–O–), and FZU-303 (–CH₂–) with typical 4-c sql topology were synthesized by precisely modulating edge linkers. Research revealed that the electronic structure and charge transfer properties of the 1D COFs were significantly influenced by the edge linkers. Among them, FZU-303 with an all-carbon-bridging structure exhibits a lower exciton binding energy (E_b = 33.4 meV) than most reported COFs, along with a high carrier density, superior charge separation, and excellent charge transfer efficiency. Under sacrificial agent-free conditions, FZU-303 demonstrated outstanding H₂O₂ production performance via three possible pathways: O₂ → ˙O₂⁻ → H₂O₂, O₂ → ˙O₂⁻ → ¹O₂ → H₂O₂, and H₂O → H₂O₂. Its H₂O₂ yield reached 4642 μmol g⁻¹ h⁻¹, with a solar-to-chemical energy (SCC) efficiency of 0.95%, surpassing most reported photocatalysts for H₂O₂ production. Moreover, after 12 hours of continuous photocatalytic reaction, a 4.4 mM H₂O₂ solution was obtained, which could be directly used for purifying wastewater contaminated with dyes and phenol.