Covalent organic frameworks (COFs) are crystalline structures composed of conjugated organic molecules, forming two-dimensional or three-dimensional frameworks.

Currently, most efforts in designing COFs catalysts focus on altering the types of monomers and adjusting the framework's charge to achieve highly efficient catalysts. However, these efforts often overlook the impact of water molecules binding to nitrogen atoms within the COFs during the catalytic process, which can significantly affect the catalyst's performance.

Recently, a research group led by prof. ZENG Gaofeng and XU Qing at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, represents the first investigation into the solvent effect on COFs for catalyzing the oxygen reduction reaction (ORR). They found all COFs synthesized with different nitrogen atoms exhibited good crystallinity and high surface areas, but displayed different binding abilities towards water molecules.

This work was published in Angew. Chem. In. Ed.

Researcher synthesized three COFs composed of different N kinds including imine, pyridine, and phenazine N. The interaction between the N atoms and H₂O resulted in modifying electronic states and corresponding catalytic performance for the COFs. The COFs with pyridine N achieved higher catalytic activity compared to those COFs based on imine N and phenazine N sites.

The theoretical calculation later revealed that the stronger binding ability of *OOH intermediates to the carbon atoms near the pyridine N sites may contribute to its higher activity.

This work provides valuable insights into the significance of putting solvent effects on COFs in electrocatalytic systems design offering a new approach for their design and enhancement of electrocatalytic performance.