Dimensional Upgrade Induced Enriched Active Sites and Intensified Intramolecular Electron Donor–Acceptor Interaction to Boost Oxygen Reduction Electrocatalysis

Journal article

Conjugated 2D covalent organic frameworks (2D‐COFs) have garnered interest as potential cost‐efficient noble‐metal‐free electrocatalysts, owing to their structural flexibility, well‐defined molecular architecture, high compatibility, and environmental sustainability. However, their suboptimal activity, primarily attributed to their low active site utilization and limited electron transfer ability, considerably impedes their implementation in real‐world electrocatalytic systems. Herein, the molecular dimensionality of a 2D‐COF containing tris‐triazine ring (2D‐Tr‐COF) is upgraded to generate its 3D counterpart (3D‐Tr‐COF), enabling a direct comparison between 2D‐ and 3D‐ COFs. These findings reveal that slightly altering the spatial structure in plane (from 2D to 3D) by substituting amine building blocks leads to significant variations in molecular architecture and performance for oxygen reduction reaction. The results indicate that 3D‐Tr‐COF with enlarged lattice spacing, more active species, and reduced conjugated degree, possesses enriched active sites. Moreover, the intensified intramolecular electron donor–acceptor interaction between the tris‐triazine ring and its neighboring imino linkage of 3D‐Tr‐COF optimizes the electronic/band structure and facilitates the charge transfer, resulting in enhanced intrinsic activity compared to 2D‐Tr‐COF. The extensively optimized 3D‐Tr‐COF demonstrates a half‐wave potential of 0.833 V, on par with the state‐of‐the‐art Pt/C. These findings offer valuable insights into dimension modulation strategies for COF‐based electrocatalyst designing.

Authors: Cheng, R; Ran, B; Zhang, X; Han, Y; Shao, X

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Advanced Functional Materials
• Article number: 2406717
• Publication date: 2024-06-18
• DOI: 10.1002/adfm.202406717
• EISSN: 1616-3028
• ISSN: 1616-301X and 1616-3028
• Language: English
• Keywords: active site enrichment; compatible covalent organic framework; intramolecular electron donor–acceptor effect; dimensional upgrade; electrocatalytic activity indicator