Integrating β-ketoenamine linkages into covalent organic frameworks toward efficient overall photocatalytic hydrogen peroxide production

Abstract

Covalent organic frameworks (COFs) are promising photocatalysts for hydrogen peroxide (H₂O₂) production from water and oxygen. However, the H₂O₂ generation from a dual-channel pathway, the oxygen reduction reaction (ORR), and especially the water oxidation reaction (WOR), is still challenging for COF photocatalysts. Here, a series of COFs were constructed by introducing different amounts of hydroxy groups into the COF skeleton to adjust the redox potentials, exciton dissociation and active center. Overall, the β-ketoenamine-linked COF, Tz–THBZ, exhibited a more positive oxidation potential and lower exciton binding energy, leading to efficient photo-excited electron and hole separation ability, and shows an overall photocatalytic H₂O₂ production yielding a rate of 4688 μmol h⁻¹ g⁻¹ in pure water. Density functional theory calculations further demonstrate the keto-formed benzene and triazine rings as the photooxidation and reduction centers.