基于超分子自组装二维共价有机框架的构建及其光催化CO2还原性能研究

具有延展π共轭体系的二维共价有机框架(2D-COFs)已经被证实可用于光催化能源转换，相对于非晶态的共轭多孔聚合物，2D-COFs往往表现出更为优异的光催化性能，这一定程度上归因于其层间非共价作用导致的高度有序的层间堆叠。本项目以集光敏剂和活性位点为一体的金属配位联吡啶基2D-COFs为对象，旨在研究层间非共价作用力对光催化CO2还原转化效率和选择性的影响。拟采用超分子富电/缺电芳香环交替自组装策略，通过芳香环功能化实现层间非共价相互作用力优化，构建取代/未取代芳香环交替全堆叠的2D-COFs。综合利用光催化CO2还原结果，探究非共价作用力对载流子迁移的影响，同时结合芳香环功能化协同调控层内有机骨架2p电子激发到螯合金属3d空轨道的原理，深入分析活性位点在对CO2吸附、多电子转移中的作用机制，揭示2D-COFs光催化还原CO2构效关系，拓展超分子组装在提升COFs光催化能源转换领域的应用。

Two-dimensional covalent organic frameworks (2D-COFs) with extended π conjugation have been proven to be used for photocatalytic energy conversion. Compared with amorphous conjugated porous polymers, 2D-COFs tend to show superior performance. The photocatalytic performance is partly due to the highly ordered interlayer stacking caused by non-covalent interactions between the layers. This project aims to design series of 2D metal coordination bipyridyl based 2D-COFs COFs with embelded photosensitizers and active sites, and the effect of non-covalent interaction between layers on the efficiency and selectivity of photocatalytic CO2 reduction conversion is studied. It is planned to adopt a supermolecular electron rich/deificient aromatic ring alternating self-assembly strategy. Through functionalization of aromatis, non-covalent interaction forces between layers are optimized, 2D-COF with substituted/unsubstituted alternating eclipsed aromatics are constructed. Combined with the experimental results of photocatalytic CO2 reduction, the effect of non-covalent forces on carrier migration is first explored. Along with the principle of aromatics functionalization to coordinately regulate excitation of the organic skeleton 2p electrons in the layer to chelated metal 3d empty orbit, in-depth analysis of the mechanism of anchored metal active sites in CO2 adsorption and multi-electron transfer will be conducted, and then structure-activity relationship of 2D-COFs based photocatalytic reduction of CO2 is developed. Finally, it is expected to expand the application of supramolecular assembly chemistry in the field of 2D-COFs design for enhancing photocatalytic energy conversion.