Fluorine tuning of nickel phthalocyanine electrocatalysts for stable and rapid CO₂ reduction to CO

Due to their high selectivity, nickel phthalocyanine (NiPc) based molecular electrocatalysts supported on carbon nanotubes have been regarded as promising candidates for electrochemical CO₂-to-CO conversion. However, it lacks effective strategies to simultaneously enhance the intrinsic activity and stability of NiPc electrocatalysts. Here, we show that fluorine tuning of NiPc can address this limitation. As a bridging study, incorporating polytetrafluoroethylene (PTFE) is shown to facilitate CO desorption near active sites, thereby enhancing electrochemical stability but reducing activity due to partial site masking. Building on this insight, β-site fluorination of NiPc affords a robust electrocatalyst (NiPc–F) with enhanced intrinsic CO₂-to-CO activity and durability. Microenvironment and operando studies reveal that fluorination improves CO₂ adsorption and enhances CO desorption, resulting in intact Ni–N₄ coordination during electrocatalysis. The optimized NiPc-F catalyst delivers stable operation at −300 milliamperes per square centimeter for 45 hours in neutral electrolytes, with CO Faradaic efficiencies over 98 percent.