Pyridine-Based Covalent Organic Frameworks with Pyridyl-Imine Structures for Boosting Photocatalytic H₂O₂ Production...

Bipyridine-based covalent organic frameworks (COFs) have emerged as promising contenders for the photocatalytic generation of hydrogen peroxide (H₂O₂). However, the presence of imine nitrogen alters the mode of H₂O₂ generation from an efficient one-step two-electron (2e^-) route to a two-step 2e^- oxygen reduction pathway. In this work, we introduce 3,3'-bipyridine units into imine-based COF skeletons, creating a pyridyl-imine structure with two adjacent nitrogen atoms between the pyridine ring and imine linkage. This unique bipyridine-like architecture can effectively suppress the two-step 2e^- ORR process at the single imine-nitrogen site, facilitating a more efficient one-step 2e^- pathway. Consequently, the optimized pyridyl-imine COF (PyIm-COF) exhibits a remarkable H₂O₂ production rate of up to 5850 μmol h^-1 g^-1, nearly double that of pristine bipyridine COFs. This work provides valuable insight into the rational design of functionalized COFs for enhanced H₂O₂ production in photocatalysis.