Zhang Jiahe, Li Xiaoning, Hu Haijun, Huang Hongwei, Li Hui, Sun Xiaodong, Ma Tianyi
Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang, People's Republic of China.
Centre for Atomaterials and Nanomanufacturing (CAN), School of Science, RMIT University, Melbourne, Australia.
Nat Commun. 2024 Nov 6;15(1):9576. doi: 10.1038/s41467-024-53834-w.
Covalent organic frameworks have emerged as a thriving family in the realm of photocatalysis recently, yet with concerns about their high exciton dissociation energy and sluggish charge transfer. Herein, a strategy to enhance the built-in electric field of series β-keto-enamine-based covalent organic frameworks by ionic polarization method is proposed. The ionic polarization is achieved through a distinctive post-synthetic quaternization reaction which can endow the covalent organic frameworks with separated charge centers comprising cationic skeleton and iodide counter-anions. The stronger built-in electric field generated between their cationic framework and iodide anions promotes charge transfer and exciton dissociation efficiency. Moreover, the introduced iodide anions not only serve as reaction centers with lowered H* formation energy barrier, but also act as electron extractant suppressing the recombination of electron-hole pairs. Therefore, the photocatalytic performance of the covalent organic frameworks shows notable improvement, among which the CHI-TpPa-1 can deliver an high H production rate up to 9.21 mmol g h without any co-catalysts, representing a 42-fold increase compared to TpPa-1, being comparable to or possibly exceeding the current covalent organic framework photocatalysts with the addition of Pt co-catalysts.
共价有机框架最近已成为光催化领域中一个蓬勃发展的家族，但人们对其高激子解离能和缓慢的电荷转移存在担忧。在此，提出了一种通过离子极化方法增强基于β-酮烯胺的系列共价有机框架的内建电场的策略。离子极化通过独特的合成后季铵化反应实现，该反应可赋予共价有机框架由阳离子骨架和碘化物抗衡阴离子组成的分离电荷中心。在其阳离子框架和碘化物阴离子之间产生的更强内建电场促进了电荷转移和激子解离效率。此外，引入的碘化物阴离子不仅作为具有降低的H*形成能垒的反应中心，还作为电子萃取剂抑制电子-空穴对的复合。因此，共价有机框架的光催化性能有显著提高，其中CHI-TpPa-1在没有任何助催化剂的情况下可实现高达9.21 mmol g h的高H产率，与TpPa-1相比提高了42倍，与添加Pt助催化剂的当前共价有机框架光催化剂相当或可能超过它们。
