Differential Adaptation between Active Sites and Charge‐Transport Networks in Covalent Organic Frameworks for H 2 O 2 Photosynthesis

ABSTRACT Covalent organic frameworks (COFs) are promising photocatalysts for H 2 O 2 production. However, optimizing their electronic structure to enhance oxygen activation, charge separation, and transport remains challenging. Herein, a dual‐dimensional COF platform was constructed by integrating diazine isomers, pyridazine (Dz) and pyrazine (Pz), with tunable linkage chemistries (sp 2 c‐, mix‐, and imi‐linked), enabling decoupled regulation and systematic investigation of active‐site electronic environments and framework charge‐transport behavior. Experiments and theoretical calculations revealed that N ‐heterocyclic isomers primarily govern O 2 activation configurations and oxygen reduction reaction pathways, whereas linkage chemistry mainly regulates framework charge transport. More importantly, a previously unrecognized differential adaptation mechanism is revealed: in the intrinsically asymmetric Dz systems, highly conjugated sp 2 c linkages further enhance electron delocalization and transport, maximizing photocatalytic performance and enabling sp 2 c‐COF‐Dz to achieve the highest H 2 O 2 production rate (9270 µmol h −1 g −1 ); in contrast, in the Pz systems, mixed‐linkage architectures generate localized electron‐density gradients that compensate for insufficient site polarization by disrupting electronic symmetry, resulting in higher activity than the sp 2 c‐linked COF. These findings uncover a matching relationship between active‐site electronic structures and linkage‐mediated charge transport behavior, providing a site‐framework matching principle for the rational design of high‐performance COF photocatalysts.