Fluorine tuning of nickel phthalocyanine electrocatalysts for stable and rapid CO 2 reduction to CO

Abstract 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 mA·cm−2 for 45 h in neutral electrolytes, with CO Faradaic efficiencies over 98%.