噻吩基二维共价有机框架中的拓扑结构诱导局部电荷极化促进光催化制氢  

Topology-induced local electric polarization in 2D thiophene-based covalent organic frameworks for boosting photocatalytic H_(2) evolution

作　　者：白浚贤 沈荣晨 梁桂杰[2] 秦朝朝[3] 许第发[4] 胡浩斌[5] 李鑫[1] Junxian Bai;Rongchen Shen;Guijie Liang;Chaochao Qin;Difa Xu;Haobin Hu;Xin Li(Institute of Biomass Engineering,Key Laboratory of Energy Plants Resource and Utilization,Ministry of Agriculture and Rural Affairs,South China Agricultural University,Guangzhou 510642,Guangdong,China;Hubei Key Laboratory Low Dimens Optoelect Mat&Devices,Hubei University of Arts and Science,Xiangyang 441053,Hubei,China;Henan Key Laboratory of Infrared Materials and Spectrum Measures and Applications,School of Physics,Henan Normal University,Xinxiang 453007,Henan,China;Hunan Key Laboratory of Applied Environmental Photocatalysis,Changsha University,Changsha 410022,Hunan,China;Key Laboratory of Efficient Utilization of Oil and Gas Resources in Longdong,College of Petroleum and Chemical Engineering,Longdong University,Qingyang 745000,Gansu,China)

机构地区：[1]华南农业大学生物质工程研究院,农业部能源植物资源与利用重点实验室,广东广州510642 [2]湖北文理学院低维光电材料与器件重点实验室,湖北襄阳441053 [3]河南师范大学物理学院,红外材料与光谱测量及应用重点实验室,河南新乡453007 [4]长沙大学应用环境光催化重点实验室,湖南长沙410022 [5]陇东学院石油化工学院,陇东油气资源高效利用重点实验室,甘肃庆阳745000

出　　处：《Chinese Journal of Catalysis》2024年第4期225-236,共12页催化学报（英文）

基　　金：国家自然科学基金(21975084);国家自然科学基金(51672089);广东省自然科学基金(2021A1515010075)。

摘　　要：共价有机框架(COFs)是近年来新兴的一类多孔聚合物,在气体吸附、传感器、能源转换和光/电催化等领域表现出较大的应用潜力.然而,欲实现多样化的应用需求常需要对其结构进行合成后改性,这在单一步骤中难以实现.二维亚化学计量共价有机框架(2D-SSCOFs)因其独特的周期性官能团和保持结晶性及孔隙率的能力,成为COFs功能化的新途径.然而,已报道的2D-SSCOFs多具有相同的拓扑结构以及弱电荷极化等问题,限制了其应用潜力.因此,开发具有新颖拓扑结构的2D-SSCOFs对于实现更前沿的功能至关重要.窄带隙噻吩是有机半导体材料的常见单元,它们可以显著地调控共价聚合物骨架的电子和化学环境.本文通过5,5',5''-(苯-1,3,5-三基)三(噻吩-2-甲醛)(TT-3CHO)与4,4',4'',4''-(芘-1,3,6,8-四基)四苯胺(PY-4HN2)的席夫碱缩合反应合成具有大表面积和高结晶度的亚胺连接的新型2D-SSCOF(PTT-COF).噻吩环中2,5位之间的键的弯曲角度使得PTT-COF具有新型的2D亚化学计量拓扑结构,并呈现出非中心对称的优势极化结构.在使用有机空穴传输配体(二茂铁甲醛,FC)精确修饰和Pt作为助催化剂时,PTT-COF-FC体系在可见光照明下表现出较高的析氢产率(79.610 mmol g^(-1) h^(-1)).同时,在420 nm波长的光照下,2 mg的光催化剂表观量子效率达到1.72%.此外,经过24 h循环稳定性测试,PTT-COF-FC体系的活性没有明显下降.为了深入研究PTT-COF-FC体系的高效的产氢机制,通过X射线衍射、红外和固体碳谱等对PTT-COF-FC体系的组成和结构进行分析,确定了PTT-COF-FC的成功合成.通过瞬态吸收、变温荧光和理论计算等研究了材料的激子解离和载流子转移行为.结果表明,得益于独特的富含噻吩的结构设计以及有机空穴传输配体的修饰作用,PTT-COF-FC展现出高效的激子解离和丰富的自由电荷载流子特性.综上所述,本文设计和合成了一种新型PTT-COF光催�2D Substoichiometric covalent organic frameworks(2D-SSCOFs)are a new kind of porous organic polymers with accurate modifiability,good stability and abundant porosity.However,the strong exciton effects and slow charge transfer in 2D-SSCOFs can severely linker hinder the efficiency of photocatalytic energy conversion.Herein,we report a brand new thiophene-based 2D-SSCOF(PTT-COF)constructed by the Schiff base reaction using thiophene-enriched tri-topic linker and tetra-topic pyrene as structural unit precursors.Interestingly,PTT-COF exhibits a novel topology,high crystallinity,abundant delocalization electrons and weak excitonic effects.Inspired by the unique structural characteristics and photoelectrical performance,PTT-COF is utilized for photocatalytic hydrogen evolution.Experimental and theoretical studies have confirmed that introducing thiophene effectively modulates the topology of the COF,inducing local charge delocalization and redistribution,thus suppressing the excitonic effect and enhancing the photocatalytic performance.In addition,the periodic,uncondensed functional groups allow PTT-COF to be accurately modified by ferrocene carboxaldehyde as organic hole transporting ligands,leading to a further 40%enhancement in hydrogen evolution rate up to 79.610 mmol g^(-1) h^(-1).These findings in this work not only offer a brand new 2D-SSCOF with novel topology,but also provide new opportunities and directions for the ration design of 2D-SSCOF for emerging functional applications.

关 键 词：光催化产氢 电荷分离 亚化学计量共价有机框架 拓扑结构 激子效应 

分 类 号：O643.36[理学—物理化学] O644.1[理学—化学] TQ116.2[化学工程—无机化工]