(726d) Sustainable Chemical Production through Two-Step CO2 Electrolysis

The electrochemical conversion of CO₂ to value-added products is a promising technology for the sustainable production of fuels and chemicals. Multi-carbon (C₂₊) products such as ethylene and ethanol are particularly attractive due to their large market potential. The use alkaline electrolyte enhances C₂₊ product formation, but CO₂ electrolysis in basic conditions is fundamentally unsustainable due to carbonate formation that results in loss of both CO₂ and electrolyte. This talk will present our recent work in developing a two-stage electrolysis process for the conversion of CO₂ to C₂₊ products that is decoupled through the carbon monoxide (CO) intermediate, where CO₂ is initially converted to CO under neutral conditions, and the produced CO is then further converted to C₂₊ products in alkaline conditions.
We demonstrate a high-performance CO flow electrolyzer with a well-controlled electrode–electrolyte interface that can achieve a C₂₊ selectivity of >90% at industrially relevant reaction rates. Additionally, we show that CO electrolysis leads to significant acetate production relative to CO₂ electrolysis under identical conditions. We utilized transport modeling of the electrocatalytic interface, density functional theory (DFT) calculations, and isotopic labelling studies to probe the reaction mechanism, and conclude that the enhanced acetate formation for CO electrolysis is likely due to a higher surface pH where acetate forms through nucleophilic hydroxide attack of a ketene-like intermediate. We then performed CO electrolysis in the presence of nucleophilic amines and form acetamides, demonstrating the formation of heteroatomic products, which greatly expands the scope of possible CO₂ electrolysis derived chemicals.