Structural regulation of covalent organic frameworks via isomerism for enhanced photocatalytic hydrogen peroxide production

Abstract

Covalent organic frameworks (COFs) have emerged as promising photocatalysts due to their well-defined porous structures and structural versatility. Among various design strategies, isomerism offers an efficient yet underexplored approach to modulating the structural and electronic properties of COFs without altering their chemical compositions. In this work, two regioisomeric COFs were rationally synthesized from isomeric cyano-substituted distyrylnaphthalene-based monomers to systematically investigate the effect of regioisomerism on photocatalytic behavior. Despite their identical chemical compositions, the two COFs exhibit distinct pore structures and markedly different photocatalytic performance. Notably, Trans-COF exhibited a significantly higher H₂O₂ production rate of 3.34 mmol g ^-1 h ^-1 using 10% benzyl alcohol as a sacrificial agent, approximately three times higher than that of Cis-COF. Combined experimental and theoretical studies revealed that regioisomerism critically modulates the optoelectronic properties and charge-transfer characteristics of COFs, thereby governing their photocatalytic activity. This work provides new insights into the molecular-level rational design of efficient COF-based photocatalysts