(658a) Significantly Improved Efficiency of CO2/CO Electroreduction to Value-Added Liquid Fuels Via Rational Catalyst Design

To improve the efficiency of CO2 reduction reaction (CO2RR) to high valuable multi-carbon products, substantial progress has been made on the development of gas-diffusion type flow cells (e.g., microfluidic reactors and membrane electrode assembly electrolyzers) to improve the mass transport of CO2. A reservoir of flowing highly alkaline electrolyte is typically used in these electrolyzers, with the purpose of increasing the full-cell energy efficiency by reducing the voltage required to drive the coupled anodic oxygen evolution reaction. However, the use of highly alkaline electrolytes inevitably leads to electrolyte degradation and coking of the electrode due to the carbonate formation caused by the chemical reaction of CO2 and OH^-, which poses great challenges to the improvement of carbon efficiency to support commercial applications. In a few recent studies, the carbonate formation problem has been effectively reduced by conducting CO2 electrolysis in strong acid media or directly implementing carbonate to CO2RR products. Despite the progress, the energy efficiency for the multi-carbon products is below expectation due to their low total Faradaic efficiency achieved at those conditions. The use of CO instead of CO2 as the feedstock offers a means to address these challenges resulted from the undesired side reaction or low selectivity. In light of the comparatively mature electrochemical conversion of CO2 to CO in non-alkaline conditions (e.g., in strong acid media or using solid oxide electrochemical cell) with high efficiency, the tandem strategy in which CO2 is first reduced to CO followed by further reducing CO to multi-carbon products shows significant promise. Herein we report our latest progress in CO electroreduction using both metal and molecular catalysts to achieve high efficiency towards value-added liquid fuels^[1]. Our efforts in providing mechanistic insights including reaction intermediates and pathways will also be discussed.

[1] Jing Li, et al. Nature communications, 14, 698 (2023).