Electrocatalytic CO₂ reduction into multielectron products is a promising approach for carbon capture and utilization. Recently, cobalt phthalocyanine (CoPc)-based molecular catalysts have shown potential competence toward electrochemical conversion of CO₂ to methanol, a 6e⁻/6H⁺ product. Yet, despite the recent advancements, CoPc’s tendency to aggregate and the weak CO-intermediate binding generally limit its electrocatalytic activity and selectivity. Herein, we demonstrate that a metal−organic framework (MOF) could be used to construct a tandem electrocatalytic system via immobilization of 2 types of molecular catalysts (CoPc and Fe-porphyrin). Notably, the MOF-based tandem achieves a 3-fold increase in electrocatalytic CO₂-to-methanol activity and selectivity compared to a CoPc-only MOF-based catalyst (up to 18% methanol faradaic efficiency at 25 mA/cm²). Additionally, operando spectroscopy and electrochemical analysis show that unlike typical tandem systems, the MOF-based tandem operates uniquely by using a reactive intermediate different from CO (i.e., formaldehyde). Hence, this proof-of-concept approach offers a new means to design molecular electrocatalytic schemes capable of driving complex proton-coupled electron transfer reactions.

中文翻译：

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基于双分子催化剂的串联反应，可实现电催化 CO2-甲醛-甲醇级联转化

电催化 CO₂ 还原成多电子产物是一种很有前途的碳捕获和利用方法。最近，基于钴酞菁 （CoPc） 的分子催化剂已显示出将 CO₂ 电化学转化为甲醇（一种 6e⁻/6H⁺ 产物）的潜在能力。然而，尽管最近取得了进展，但 CoPc 的聚集倾向和较弱的 CO 中间体结合通常会限制其电催化活性和选择性。在此，我们证明了金属有机框架 （MOF） 可用于通过固定 2 种分子催化剂（CoPc 和 Fe-卟啉）构建串联电催化系统。值得注意的是，与仅基于 CoPc 的 MOF 催化剂相比，基于 MOF 的串联物的电催化 CO₂ 制甲醇活性和选择性提高了 3 倍（在 25 mA/cm² 时甲醇法拉第效率高达 18%）。此外，原位光谱和电化学分析表明，与典型的串联系统不同，基于 MOF 的串联系统通过使用不同于 CO（即甲醛）的反应性中间体来独特地运行。因此，这种概念验证方法提供了一种新方法来设计能够驱动复杂质子耦合电子转移反应的分子电催化方案。