Dimensional Engineering of 1D/2D Covalent Organic Framework Isomers for Enhanced CO₂ Photoreduction

Abstract The rigorous topologic 1D covalent organic frameworks (1D‐COFs) require highly anisotropic and aligned connectivity, making their synthesis as isomers with low‐dimensional structures challenging, let alone understanding the long‐sought consensus regarding the structure‐property relationship. Here, a feasible dimensional engineering strategy is demonstrated to construct 1D/2D COF isomers, revealing their dimensional contributions on the photocatalytic CO 2 reduction reaction (CO 2 ‐RR) performance. By leveraging the cis/trans conformational flexibility of 2,2′‐bipyridine‐4,4′‐dicarboxaldehyde (BPY) under acidity regulation, this study successfully constructs 1D/2D BPY‐COF dimensional isomers for the first time. To give prominence to the dimensional topological effect, the post‐modification of cobalt (Co 2+ ) is coordinated with bipyridine in 1D/2D‐BPY‐COFs. Notably, the unique 1D chain structure and more exposed catalytic sites on the edge of 1D‐BPY‐COF‐Co, significantly facilitate the orientational electron transfer, making the formation energy ( ΔG COOH * ) for COOH * lowering from 0.78 eV in 2D‐BPY‐COF‐Co to 0.25 eV. This structural advantage contributes to an exceptionally high CO yield of 1645 µmol g −1 h −1 with 100% selectivity, which exceeds that of the corresponding 2D counterpart by a factor of 108. This work initiates a new progress for dimensional control in reticular chemistry, providing fundamental insights into the molecular‐level mechanisms governing photocatalytic CO 2 reduction.