Abstract：
Artificial photosynthesis represents a sustainable strategy for accessing high-value chemicals; however, the conversion efficiency is significantly limited by its difficulty in the cycle of coenzymes such as NADH. In this study, we report a series of isostructural triazine covalent organic frameworks (COFs) and explore their N-substituted microenvironment-dependent photocatalytic activity for NADH regeneration. We discovered that the rational alteration of N-heterocyclic species, which are linked to the triazine center through an imine linkage, can significantly regulate both the electron band structure and planarity of a COF layer. This results in different separation efficiencies of the photoinduced electron-hole pairs and electron transfer behavior within and between individual layers. The optimal COF catalyst herein achieves an NADH regeneration capacity of 89% within 20 min, outperforming most of the reported nanomaterial photocatalysts. Based on this, an artificial photosynthesis system is constructed for the green synthesis of a high-value compound, L-glutamate, and its conversion efficiency significantly surpasses the enzymatic approach without the NADH photocatalytic cycle. This work offers new insights into the coenzyme regeneration by means of regulating the distal heterocyclic microenvironment of a COF skeleton, holding great potential for the green photosynthesis of important chemicals.
摘要：
人工光合作用代表了获取高价值化学品的可持续战略；然而，其在辅酶如NADH的循环中的困难显著地限制了转化效率。在这项研究中,我们报道了一系列同构三嗪共价有机骨架（COFs），并探索了其N取代的微环境依赖性的NADH再生光催化活性。我们发现N-杂环物种的合理变化，它们通过亚胺键连接到三嗪中心，可以显着调节COF层的电子能带结构和平面性。这导致光诱导电子-空穴对的不同分离效率以及各个层内和层间的电子转移行为。本文的最佳COF催化剂在20分钟内实现了89%的NADH再生能力，优于大多数报道的纳米材料光催化剂。基于此,构建了一个人工光合作用系统，用于绿色合成高价值化合物，L-谷氨酸,其转化效率明显超过无NADH光催化循环的酶法。这项工作通过调节COF骨架的远端杂环微环境，为辅酶再生提供了新的见解，对重要化学物质的绿色光合作用具有巨大潜力。
