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H_(2)O_(2)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H_(2)O_(2)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O_(2)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H_(2)O_(2)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.
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 H_(2)O_(2)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 H_(2)O_(2).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 O_(2)adsorption and activation,and the strong electron transfers from COFs to O_(2)and ORR intermediates enable a two-step single-electron reduction route of O_(2)in pyridine-functionalized COFs for a more feasible H_(2)O_(2)generation(706.2μmol g^(−1)h^(−1))than original imine-linked COF(372.7μmol g^(−1)h^(−1))under visible light irradiation.This work provides a new idea for designing and modifying imine-linked COFs in advanced photocatalytic applications.
作者
周诗健
胡浩
胡会康
蒋其超
谢浩然
李常来
高树英
孔岩
胡应杰
Shijian Zhou;Hao Hu;Huikang Hu;Qichao Jiang;Haoran Xie;Changlai Li;Shuying Gao;Yan Kong;Yingjie Hu(State Key Laboratory of Materials-Oriented Chemical Engineering,College of Chemical Engineering,Nanjing Tech University,Nanjing 210009,China;Key Laboratory of Advanced Functional Materials of Nanjing,Nanjing Xiaozhuang University,Nanjing 211171,China;Ganjiang Innovation Academy,Chinese Academy of Sciences,Ganzhou 341119,China)
基金
supported by the National Natural Science Foundation of China(21776129,21706121,and U22B6011)
the Natural Science Foundation of Jiangsu Province(BK20170995 and BK20201120)
the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
