Tuning Linkage and Dimensionality in Covalent Organic Frameworks for Enhanced Photocatalytic Hydrogen Peroxide Production

We report the synthesis of two-dimensional (2D) and three-dimensional (3D) covalent organic frameworks (COFs) for photocatalytic hydrogen peroxide (H 2 O 2 ) production. Pyrene-based 2D COF ( 1 ) and 3D COF ( 2 ) were synthesized to investigate the effect of COF dimensionality on photocatalytic performance. By treating them with trimethyloxonium tetrafluoroborate, the imine bonds in the COFs were methylated, yielding 2D and 3D pyrene-based iminium-linked COFs 3 and 4, respectively. These COFs exhibited strong and broad visible-light absorption, significantly enhancing photocatalytic efficiency. The methylated 3D COF ( 4 ) achieved a high H 2 O 2 production rate of 1839 μmol·g –1 ·h –1 and maintained its performance over multiple cycles. This work introduces a strategy for optimizing COF photocatalytic performance and highlights the potential of 3D COFs in solar energy conversion applications.