催化学报 ›› 2024, Vol. 66: 181-194.DOI: 10.1016/S1872-2067(24)60132-4

• 论文 • 上一篇    下一篇

构筑多组分供体-受体共价有机框架以实现高效光催化氧化: 电子迁移率和超氧自由基生成量的调控

张璐a,b,1, 张候瑞a,b,1, 朱东阳c, 付紫涵a,b, 董双石a,b, 吕聪a,b,*()   

  1. a吉林大学地下水资源与环境教育部重点实验室, 吉林长春 130026, 中国
    b吉林大学水资源与环境吉林省重点实验室, 吉林长春 130026, 中国
    c莱斯大学化学与生物分子工程系, 德克萨斯州, 美国
  • 收稿日期:2024-06-19 接受日期:2024-09-04 出版日期:2024-11-18 发布日期:2024-11-10
  • 通讯作者: *电子邮箱: lvcong@jlu.edu.cn (吕聪).
  • 作者简介:1共同第一作者.
  • 基金资助:
    国家自然科学基金(52070086);国家重点研发计划(2020YFC1808804);吉林省科技厅(20220101214JC);吉林省科技厅(20220508100RC);中央高校基本科研业务费(45122031D027);吉林大学研究生创新研究计划

Construction of multivariate donor-acceptor heterojunction in covalent organic frameworks for enhanced photocatalytic oxidation: Regulating electron transfer and superoxide radical generation

Lu Zhanga,b,1, Hourui Zhanga,b,1, Dongyang Zhuc, Zihan Fua,b, Shuangshi Donga,b, Cong Lyua,b,*()   

  1. aKey Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130026, Jilin, China
    bJilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130026, Jilin, China
    cDepartment of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston77005, Texas, United States
  • Received:2024-06-19 Accepted:2024-09-04 Online:2024-11-18 Published:2024-11-10
  • Contact: *E-mail: lvcong@jlu.edu.cn (C. Lyu).
  • About author:1Contributed equally to this work.
  • Supported by:
    National Natural Science Foundation of China(52070086);National Key Research and Development Program of China(2020YFC1808804);Department of Science and Technology of Jilin Province(20220101214JC);Department of Science and Technology of Jilin Province(20220508100RC);Fundamental Research Funds for the Central Universities(45122031D027);Graduate Innovation Foundation of Jilin University

摘要:

光催化技术可将丰富的太阳能转化为化学能, 具有高效、低耗的优势, 在水污染治理领域具有较好的应用前景. 三嗪基共价有机框架(COFs)具有良好的π共轭平面、高的比表面积和孔隙率、易于功能化和分子结构可调等特点, 作为高效的可见光响应型光催化剂被广泛研究, 但其仍存在电子-空穴复合率较高的问题. 在COFs骨架中构筑供体-受体(D-A)结构可有效降低电荷复合率, 由此, 本研究创新性地构筑了多组分供体-受体D-A COFs以增强电子迁移率和活性氧物种(ROS)的生成量, 并通过调控其结构实现有机污染物的高效光催化氧化降解.

本文在三嗪基COFs中同步引入吸电子(-Br, -Cl)和供电子取代基(-OCH3, -OC3H7和-OC8H17)构建了多组分D-A COFs, 并通过调控电子供体的碳链长度来改善其光电特性和光催化性能. 粉末X射线衍射实验和理论结构模拟结果表明, D-A COFs晶型良好, 为AA堆叠模式. 傅里叶变换红外光谱和固体核磁共振等结果证明D-A COFs被成功合成. 扫描电镜、透射电镜和N2吸附-解吸曲线结果表明, 多组分D-A COFs是介孔材料, 形貌呈现纤维状, 有清晰的晶格条纹, 具有大的比表面积和丰富的活性位点. 紫外-可见漫反射光谱和价带X射线光电子能谱结果表明, D-A COFs材料具有宽可见光吸收范围, 构建多组分D-A COFs可缩短带隙, 提高导带位置. 瞬态光电流响应、光致发光光谱、电化学阻抗曲线、线性扫描伏安曲线、量子产率等光电化学性质表征证明多组分D-A COFs电荷载流子的产生、分离、迁移和利用均增强. 多组分D-A COFs (COF-Br@R (R = OCH3, OC3H7, OC8H17))光催化降解四环素(TC)的速率分别是传统D-A COFs (COF-H)的12.8, 16.2和19.4倍. 在最佳反应条件下, COF-Br@OC8H17可在20 min实现对TC的完全去除, 与文献报道的催化剂相比, 具有更强的TC降解能力. 猝灭实验、电子顺磁共振测试以及ROS定量实验结果表明, •OH, •O2-和h+都参与了光催化反应, 其中•O2-和h+占主导作用, 并且ROS的生成量随着电子供体碳链长度的增大而增加. 傅里叶变换衰减全反射红外光谱和密度泛函理论计算结果证实构建多组分D-A COFs可增强电荷载流子的分离效率和迁移速率, 强化•O2-的生成和转化, 以及降低形成*OH和*OOH的能垒. COF-Br@OCH3中与Br和OCH3基团相连的苯环上的邻位碳原子和亚胺键(-C=N-)被激活, 产生了关键的*OH和*OOH中间体, 与COF-H相比, 有效降低了H2O氧化和O2还原的能垒, 增强了•OH和•O2-的生成, 从而增强TC光催化降解性能. 通过高效液相色谱-质谱联用仪和毒性分析软件对TC的降解产物及其毒理性进行了分析并提出了可能的降解路径. 最后, 通过四次循环实验和反应前后的X射线衍射图谱证明D-A COFs具有良好的重复使用性和稳定性.

综上, 本文同步引入电子供体和受体取代基成功构筑了多组分D-A COFs. 与传统D-A COFs相比, 其电荷载流子分离率、电子迁移率、ROS生成量均显著增加, 降低*OH和*OOH的形成能垒, 并且其可见光催化性能随着电子供体碳链长度的增加而增强. 该研究通过调控多组分D-A COFs结构, 实现了电子迁移率和ROS生成量的定向调控, 阐明了多组分D-A COFs的构效关系, 为精准调控COFs基光催化剂的结构和理化性质以实现高效催化降解污染物提供了新的见解.

关键词: 共价有机框架, 电荷载流子分离, 电子迁移, 多组分供体-受体异质结, 超氧自由基

Abstract:

Covalent organic frameworks (COFs) have attracted attention as photocatalysts, however, low electron transfer and reactive oxygen species (ROS) generation still hinder their photocatalytic application. In this work, we construct multivariate donor-acceptor (D-A) heterojunctions in the covalent organic frameworks by synchronously introducing electron-withdrawing and donating substituents. Importantly, the optoelectronic characteristics and visible-light photocatalytic performance were improved with the increase of the electron donor carbon chains in multivariate D-A COFs. Combining in-situ characterization with theoretical calculations, the charge carrier separation and transfer efficiency, •O2- generation and conversion, and the energy barrier of the rate determination steps related to the formation of *OH and *OOH, can be well regulated by the multivariate D-A COFs. More importantly, the ortho-carbon atom of the Br and OCH3 group-linked benzene rings and the imine bond (-C=N-) in COF-Br@OCH3 were activated to produce the key *OH and *OOH intermediates for effectively reducing the energy barrier of H2O oxidation and O2 reduction. This work provides valuable insights into the precise design and synthesis of COFs-based catalysts and the regulation of electron transfer and ROS generation by modulating the electron-withdrawing and donating substituents for highly efficient visible-light photocatalytic degradation of refractory organic pollutants.

Key words: Covalent organic framework, Charge carrier separation, Electron transfer, Multivariate donor-acceptor heterojunction, Superoxide radical