Molecular catalysts offer tunable active and peripheral sites, rendering them ideal model systems to explore fundamental concepts in catalysis. However, hydrophobic designs are often regarded as detrimental for dissolution in aqueous electrolytes. Here we show that established cobalt terpyridine catalysts modified with hydrophobic perfluorinated alkyl side chains can assemble at the gas–liquid–solid interfaces on a gas diffusion electrode. We find that the self-assembly of these perfluorinated units on the electrode surface results in a catalytic system selective for electrochemical CO₂ reduction to CH₄, whereas every other cobalt terpyridine catalyst reported previously was only selective for CO or formate. Mechanistic investigations suggest that the pyridine units function as proton shuttles that deliver protons to the dynamic hydrophobic pocket in which CO₂ reduction takes place. Finally, integration with fluorinated carbon nanotubes as a hydrophobic conductive scaffold leads to a Faradaic efficiency for CH₄ production above 80% at rates above 10 mA cm⁻²—impressive activities for a molecular electrocatalytic system.

分子催化剂提供可调节的活性位点和外围位点，使其成为探索催化基本概念的理想模型系统。然而，疏水性设计通常被认为不利于在水性电解质中的溶解。在这里，我们表明，用疏水性全氟化烷基侧链修饰的已建立的三联吡啶钴催化剂可以在气体扩散电极上的气-液-固界面处组装。我们发现这些全氟化单元在电极表面上的自组装导致催化系统选择性地将CO ₂电化学还原为CH ₄ ，而之前报道的所有其他钴三联吡啶催化剂仅对CO或甲酸盐具有选择性。机理研究表明，吡啶单元充当质子穿梭机，将质子传递到发生CO ₂还原的动态疏水袋。最后，与氟化碳纳米管集成作为疏水性导电支架，在高于 10 mA cm ^-2的速率下，CH ₄生产的法拉第效率达到 80% 以上，这对于分子电催化系统来说是令人印象深刻的活性。