Tailoring Backbone Angles of Regioisomeric Covalent Organic Frameworks: Distinct O2 Adsorption Modes Enabling Efficient H2O2 Electrosynthesis.

Covalent organic frameworks (COFs) possess periodic skeletons and well-defined catalytic sites, allowing precise molecular-level regulation of interfacial properties in electrocatalytic oxygen reduction. However, conventional structural modifications fail to systematically tune oxygen adsorption geometry and interfacial electronic coupling. Here, we report a linkage-angle engineering strategy that alters the bonding positions of reactive aldehyde groups to fabricate three regioisomeric COFs with predefined backbone dihedral angles of 180°, 120°, and 60°. The angle‑driven regioisomeric effect induces considerable differences in dipole moments together with uneven charge distribution. These collective structural features remodel oxygen‑surface interactions and modulate the intrinsic catalytic kinetics. Theoretical calculations confirm that the compact 60° framework of o-TPDA-COF reconstructs confined pore interfacial microenvironments. Unlike the Griffiths‑type oxygen adsorption favored in its angular analogues, molecular oxygen preferentially adopts the Pauling configuration within o-TPDA-COF to stabilize OOH* intermediates. Consequently, the optimal o-TPDA-COF reaches an excellent H2O2 productivity of 12.82 mol gcat -1 h-1 and a Faradaic efficiency (FE) of 91.64%. This work realizes controllable modulation of oxygen‑adsorption behaviors in COF‑based 2e- oxygen reduction, delivering a novel geometry‑oriented design paradigm for porous electrocatalytic frameworks.