Abstract：
Covalent organic frameworks (COFs) have gained considerable interest as candidate photocatalysts for hydrogen evolution. In this work, we synthesized β-keto-enamine-based COFs (TpPa-X, TpDB, and TpDTP) to explore the relations between structures and photocatalytic hydrogen evolution. COFs were divided into two groups: (1) TpPa-X with different substituents attached to the TpPa backbone and (2) COFs featuring diamine linkers of varied lengths (TpDB and TpDTP). Experiments and density functional theory (DFT) calculations show that moderate hydrophobicity is favorable for the photocatalytic hydrogen evolution process, and acceptable contact angles are anticipated to range from 65° to 80°. Naturally, there are comprehensive factors that affect photocatalytic reactions, and the regulation of different backbones and substituents can considerably affect the performance of COFs for photocatalytic hydrogen evolution in terms of electronic structure, specific surface area, surface wettability, carrier separation efficiency, and hydrogen dissociation energy. Results show that TpPa-Cl2 (TpPa-X, X = Cl2) demonstrates the highest photocatalytic activity, approximately 14.51 mmol g-1h-1, with an apparent quantum efficiency of 4.62 % at 420 nm. This work provides guidance for designing efficient COF-based photocatalysts.
摘要：
共价有机骨架(COF)作为析氢的候选光催化剂已经获得了相当大的兴趣。在这项工作中,我们合成了基于β-酮-烯胺的COFs(TpPa-X，TpDB,和TpDTP）来探索结构与光催化析氢之间的关系。COF分为两组：（1）TpPa-X具有连接到TpPa主链的不同取代基，以及（2）COF具有不同长度的二胺接头（TpDB和TpDTP）。实验和密度泛函理论（DFT）计算表明，适度的疏水性有利于光催化析氢过程，并且可接受的接触角预期在65°至80°的范围内。自然,影响光催化反应的综合因素,不同的主链和取代基的调节可以在电子结构方面极大地影响COFs的光催化析氢性能，比表面积,表面润湿性,载流子分离效率,和氢离解能。结果表明,TpPa-Cl2(TpPa-X,X=Cl2)显示出最高的光催化活性，约14.51mmolg-1h-1，在420nm处的表观量子效率为4.62%。该工作为设计高效的基于COF的光催化剂提供了指导。
