中国科学院福建物质结构研究所周天华团队报道了异质结构共价-有机框架末端封盖组装中自发电荷分离增强CO₂光还原。相关研究成果于2022年10月12日发表于国际一流学术期刊《德国应用化学》。

众所周知，电荷分离对于高效的光催化太阳能转换至关重要。虽然一些共价有机框架（COFs）能够捕获可见光，但较大的激子结合能降低了它们的光催化效率。

该文中，研究人员开发了一种新的方法，用端盖多环芳烃（PAHs）对烯烃连接的COsF进行后处理，以实现自发电荷分离。有趣的是，在涤纶改性COFs中构建了一种II型异质结构，该结构在光催化CO₂还原方面表现出显著增强的性能，其效率比未改性的COF高8倍。电化学、稳态和时间分辨光谱测量结果表明，这种显著增强的性能应是由于异质结构中的光诱导自发电荷分离所致。研究结果在分子水平上说明了人工光合作用设计晶体多孔框架的电荷分离特性的可行性。

据了解，众所周知，电荷分离是高效光催化太阳能转化的关键。虽然一些共价有机框架(COFs)表现出可见光捕获，但较大的激子结合能降低了它们的光催化效率。

附：英文原文

Title: Enhanced CO2 Photoreduction through Spontaneous Charge Separation in End-Capping Assembly of Heterostructured Covalent-Organic Frameworks

Author: Huaxing Lin, Yuan Liu, Zirui Wang, Liying Ling, Hao Huang, Qiaohong Li, Linxiu Cheng, Yibao Li, Jilong Zhou, kaifeng Wu, Jian Zhang, Tianhua Zhou

Issue&Volume: 2022-10-12

Abstract: It is well known that charge separation is crucial for efficient photocatalytic solar conversion. Although some covalent-organic frameworks (COFs) exhibit visible-light harvest, the large exciton binding energies reduce their photocatalytic efficiencies. Herein, we developed a novel method to post treat the olefin-linked COFs with end-capping polycyclic aromatic hydrocarbons (PAHs) for spontaneous charge separation. Interestingly, a type-II heterostructure is constructed in our perylene modified COFs which displays drastically enhanced performance for photocatalytic CO2 reduction, with an efficiency of 8-fold higher than that of unmodified COF. A combination of electrochemical, steady-state and time-resolved spectroscopic measurements indicates that such drastically enhanced performance should be attributed to photoinduced spontaneous charge separation in the heterostructure. These results illustrate the feasibility of engineering the charge-separation properties of crystalline porous frameworks at a molecular level for artificial photosynthesis.

DOI: 10.1002/anie.202214142

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202214142