同济大学徐晓翔团队报道了用于在700 nm可见光下高效H₂O₂光合作用的，亚胺连接的共价有机框架的质子化。相关研究成果发表在2024年5月13日出版的《德国应用化学》。

共价有机框架（COFs）是通过氧还原反应（ORR）从水中生产H₂O₂的有前途的光催化剂。高效生产H₂O₂的COFs设计无疑取决于对其ORR机制的深入理解。

该文中，以亚胺连接的COF为例，研究人员证明了亚胺、胺和三嗪等功能单元的质子化是提高H₂O₂合成活性水平的高效策略。质子化不仅扩展了COF的光吸收，而且提供了直接参与H₂O₂生成的质子源。值得注意的是，质子化简化了ORR到H₂O₂的反应途径，即从间接超氧化物自由基介导的途径到直接的一步双电子途径。

理论计算证实，质子化有利于H₂O₂的合成，因为质子在反应位点附近很容易获得，这消除了生成*OOH中间体的能垒。这些发现不仅扩展了对H₂O₂光合作用的机理见解，而且为高效COFs的设计和升级提供了合理的指导。

附：英文原文

Title: Protonation of an Imine-linked Covalent Organic Framework for Efficient H2O2 Photosynthesis under Visible Light up to 700 nm

Author: Qiong Zhu, Li Shi, Zhuo Li, Guisheng Li, Xiaoxiang Xu

Issue&Volume: 2024-05-13

Abstract: Covalent organic frameworks (COFs) are promising photocatalysts for H2O2 production from water via oxygen reduction reactions (ORR). The design of COFs for efficient H2O2 production indubitably hinges on an in-depth understanding of their ORR mechanisms. In this work, taking an imine-linked COF as an example, we demonstrate that protonation of the functional units such as imine, amine, and triazine, is a highly efficient strategy to upgrade the activity levels for H2O2 synthesis. The protonation not only extends the light absorption of the COF but also provides proton sources that directly participate in H2O2 generation. Notably, the protonation simplifies the reaction pathways of ORR to H2O2, i.e. from an indirect superoxide radical ([[EQUATION]]) mediated route to a direct one-step two-electron route. Theoretical calculations confirm that the protonation favors H2O2 synthesis due to easy access of protons near the reaction sites that removes the energy barrier for generating *OOH intermediate. These findings not only extend the mechanistic insight into H2O2 photosynthesis but also provide a rational guideline for the design and upgradation of efficient COFs.

DOI: 10.1002/anie.202408041

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202408041