Pyridine-Based Covalent Organic Frameworks with Pyridyl-Imine Structures for Boosting Photocatalytic H 2 O 2 Production via One-Step 2e - Oxygen Reduction.

Bipyridine-based covalent organic frameworks (COFs) have emerged as promising contenders for the photocatalytic generation of hydrogen peroxide (H 2 O 2 ). However, the presence of imine nitrogen alters the mode of H 2 O 2 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 H 2 O 2 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 H 2 O 2 production in photocatalysis.