Covalent organic polymers (COPs) or covalent organic frameworks (COFs) are emerging types of electrode materials for electrochemical CO₂ reduction reaction (CO₂RR) owing to their controllable structures at the molecular level. However, their activities are often limited by stacking structures and low conductivities. Here we report an ultrathin cobalt tetraamino phthalocyanine-squaraine based COPs (COP-SA) for high-performance CO₂RR towards CO. The extended π-conjugated skeleton constitutes the layer, and the zwitterionic structure from the squaraine unit helps the dispersion of layers, leading to an ultrathin thickness of ∼1.7 nm. The ultrathin nanostructure avoids the common agglomeration issues for molecular catalysts and thick nanomaterials, which is beneficial to afford highly exposed active sites and efficient electron transfer for electrochemical reactions. Theoretical calculation suggests that the squaraine unit will enhance the COOH adsorption and favor the CO desorption. These collectively conduce to a high current density of 9.74 mA cm⁻² with 96.5 % CO faradaic efficiency, a large turnover frequency of 46 s^-1 (by total cobalt site) at -0.65 V vs RHE and excellent cycling stability. This work underscores the structural and electronic effects for the rational design of ultrathin COPs materials for electrochemical CO₂RR.

共价有机聚合物（COPs）或共价有机骨架（COFs ）由于其在分子水平上的可控结构而成为用于电化学CO ₂还原反应（CO ₂ RR）的新兴电极材料。但是，它们的活动通常受到堆叠结构和低电导率的限制。在这里，我们报告了用于高性能CO ₂的超薄钴四氨基酞菁-方酸钴基COP（COP-SA）相对于CO的RR。延伸的π共轭骨架构成了该层，而方酸单元的两性离子结构有助于各层的分散，从而导致约1.7 nm的超薄厚度。超薄纳米结构避免了分子催化剂和厚纳米材料常见的团聚问题，这有利于为电化学反应提供高度暴露的活性位点和有效的电子转移。理论计算表明，方酸单元将增强COOH的吸附并有利于CO的解吸。这些共同导致9.74 mA cm ^-2的高电流密度和96.5％的CO法拉第效率，46 s ^-1的大周转频率（按总钴位点计算）在-0.65 V vs. RHE的情况下，具有出色的循环稳定性。这项工作强调了电化学CO ₂ RR超薄COPs材料合理设计的结构和电子效应。