Unraveling the mechanism of anti-electrowetting in enhancing acidic CO₂ electrolysis

The electrochemical reduction of CO₂ (eCO₂RR) in alkaline media offers a way to convert greenhouse gases into valuable chemicals but faces challenges from CO₂ loss due to carbonate formation. While eCO₂RR in acidic media can effectively address these challenges, its further development is limited by the competitive hydrogen evolution reaction and electrocatalyst corrosion. Here, a hydrophobic electrocatalyst, PcCo/CNT, was developed by immobilizing phthalocyanine cobalt on carbon nanotubes. Thanks to its resistance to electrowetting, PcCo/CNT achieved over 99 % Faradaic efficiency for CO across a wide current density range (-20 to −850 mA cm⁻²) in acidic media, with a record TOF of 223 s⁻¹. In-situ experiments and theoretical calculations revealed that hydrophobic microenvironment enhances CO₂ transport and adsorption while limiting interfacial H₂O migration, boosting acidic eCO₂RR performance at high current densities. This study highlights the impact of electrowetting on electrode performance and provides guidance for designing effective acidic eCO₂RR electrocatalysts.