Covalent organic frameworks (COFs) have emerged as promising photocatalysts for the CO₂ reduction reaction (CO₂RR). Among various building components, metal phthalocyanines have gained significant attention owing to their excellent photochemical properties and well-defined M–N₄ sites. Herein, tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine cobalt(II) (CoTAPc) are used as connection points to couple with bipyridine (bpy) for constructing an imine linked CoPc-bpy COF and then coordinated with Re(CO)₃Cl to create a novel CoPc-Rebpy COF. It is found that there exists an intramolecular charge transfer from the CoPc to Rebpy units and then to Re center for CO₂RR via Z-scheme molecular heterojunction mechanism. Under visible light illumination, the CoPc-bpy and CoPc-Rebpy COFs deliver CO yields of 3068 and 6680 μmol g^–1 h^–1, respectively. The significantly increased activity of CoPc-Rebpy COF can be ascribed to the synergistic effect of Re catalytic sites and the electron capture center provided by the CoPc unit. These findings present an effective strategy for COF-based photocatalysts for CO₂RR.

中文翻译：

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钴酞菁基共价有机框架，具有双金属协同作用，用于高效光催化 CO2 还原


共价有机框架 （COF） 已成为 CO₂ 还原反应 （CO₂RR） 的有前途的光催化剂。在各种建筑构件中，金属酞菁因其优异的光化学性能和明确的 M-N₄ 位点而受到广泛关注。本文以 2,3,9,10,16,17,23,24-八羧基酞菁钴 （II） （CoTAPc） 的四酐为连接点，与联吡啶 （bpy） 偶联，构建亚胺连接的 CoPc-bpy COF，然后与 Re（CO）₃Cl 配位，产生新型 CoPc-Rebpy COF。发现存在从 CoPc 到 Rebpy 单元再到 Re 中心的分子内电荷转移，通过 Z 型分子异质结机制获得 CO₂RR。在可见光照射下，CoPc-bpy 和 CoPc-Rebpy COF 的 CO 产率分别为 3068 μmol ^g–1 h^–1。CoPc-Rebpy COF 活性的显着增加可归因于 Re 催化位点和 CoPc 单元提供的电子捕获中心的协同作用。这些发现为基于 COF 的光催化剂治疗 CO₂RR 提供了一种有效的策略。