The Linkage-Moderated Covalent Organic Frameworks with -C=N- and -N=N- on Charge Transfer Kinetics Towards the Robust Photocatalytic Hydrogen Activity

作者：Wu, Haiyang; He, Xuan^*; Du, Xing; Wang, Daheng; Li, Weixin; Chen, Hui; Fang, Wei; Zhao, Lei^*

来源：Small, 2023, 19(48).

DOI：10.1002/smll.202304367

• covalent organic frameworks
• charge transfer kinetics
• Marcus theory
• photocatalytic HER

Since the linkages structured in covalent organic frameworks (COFs) usually impact the charge transfer behavior during photocatalytic hydrogen evolution reaction (pc-HER), linkage dependence on charge transfer kinetics should be further claimed. Herein, COFs with N-based linkages and pyrene-based building nodes are constructed to enable us to obtain new clues about the charge transfer behavior and evolution tendency relevant to linkages at a molecular level for pc-HER. It is demonstrated that photo-excited electrons preferably move to the N sites in -C=N- linkage for pc-HER and are trapped around -N=N- linkage as well. A high electron transfer rate does not point to high photocatalytic activity directly, while a small difference between the electron transfer rate and electron recombination rate & UDelta;k(CT - CR) predicts the inefficiency of charge transfer in Azo-COFs. Contrarily, large value of & UDelta;k(CT - CR) in the case of Py-COFs, demonstrats an unimpeded charge transfer process to result in boosted pc-HER rate (2027.3 & mu;mol h(-1) g(-1)). This work offers a prominent strategy for the reasonable design of efficient photocatalysts at the molecular level for structural regulation and achieves an efficient charge transfer process for the pc-HER process.