【摘要】 探究氧还原反应（ORR）进行的位点是了解和提高亚胺类共价有机框架（COFs）材料光催化H₂O₂演化活性的关键.然而,与亚胺COFs中其他具有亲电或光捕获能力的基团相比,亚胺键在光化学反应中的作用往往被忽视.因此,本文提出了一种通过在亚胺键周围引入电子受体结构（吡啶单元）来激发亚胺潜在光反应性的策略,以增强亚胺在光催化ORR制备H₂O₂的动力学和热力学优势.实验和理论模拟结果表明,吡啶N的引入显著改善了TAPT-PA-COF中由弱电荷离域引起的光谱吸收和载流子分离的不足,并在TAPT-PDA-COF上表现出全光谱吸收和快速电荷转移特性.同时,吡啶N与亚胺N原子共同作为活性位点可提高O₂吸附和活化,增强光生电子在TAPT-PDA-COF表面与反应物分子间的转移.在可见光照射下,TAPT-PDA-COF的H₂O₂产率高达706.2μmol g^-1 h^-1,约为TAPT-PA-COF (372.7μmol g^-1 h^-1)的1.9倍.该工作为亚胺类COFs在高级光催化应用中的设计和改性提供了新思路.更多还原

【Abstract】 Unveiling the active site for the oxygen reduction reaction（ORR）holds the key to understanding and improving the photocatalytic activity of covalent organic frameworks（COFs）for H₂O₂ evolution.However,for iminelinked COFs,the role of the imine group is often overlooked in photosynthesis compared with other groups with electrophilicity or light-harvesting capabilities.Herein,a strategy is presented for eliciting the latent photoreactivity of imines by introducing an electron-acceptor structure（pyridine unit）near the imine bonds to enhance the kinetic and thermodynamic advantages of imines for the photocatalytic ORR to H₂O₂.Experiments and theoretical simulations indicate that the hindered visible light absorption and charge carrier separation caused by the weak electron delocalization can be substantially improved by introducing pyridinic N,leading to full solar spectrum absorption.Meanwhile,the pyridinic N can act with the N atom of the imine as an enhanced site for 02adsorption and activation,and the strong electron transfers from COFs to O₂ and ORR intermediates enable a two-step single-electron reduction route of O₂ in pyridine-functionalized COFs for a more feasible H₂O₂ generation(706.2 μmol g^-1h^-1)than original imine-linked COF(372.7 μmol g^-1h^-1)under visible light irradiation.This work provides a new idea for designing and modifying imine-linked COFs in advanced photocatalytic applications.更多还原