(646c) Co-Adsorbed Surface Hydroxide and CO Promote CO2 Electrolysis to Ethylene in Acidic Conditions

Performing CO₂ reduction (CO₂R) in acidic conditions can enable high single-pass CO₂ conversion. However, hydrogen evolution reaction (HER) prevails in acidic conditions and limits the CO₂R selectivity for multi-carbon (C₂₊) products. Herein, we present an electrodeposited copper (EC-Cu) catalyst that suppresses HER and promotes selective CO₂R to C₂₊ products in acidic conditions. Combining in situ spectroscopy, DFT calculations, and catalyst performance, we show that co-adsorbed CO and OH on the catalyst surface promote C-C coupling, which we correlate with evidence of increased CO residence time. With optimization, the EC-Cu catalyst achieved a 60% faradaic efficiency for C₂H₄ and 90% for C₂₊. Using a slim flow cell, we obtained a 20% energy efficiency toward ethylene production using the EC-Cu catalyst.