A Robust, Scalable Platform for the Electrochemical Conversion of CO₂ to Formate: Identifying Pathways to Higher Energy Efficiencies

This work demonstrated a robust, scalable cell architecture for electroreduction of CO2 (CO2R). An up to 90% faradaic efficiency for the conversion of CO2R to formate at 500 mA/cm2 was realized at a 25 cm2 gas diffusion electrode (GDE) with a carbon-supported SnO2 electrocatalyst. A 1.27 mm thick catholyte was used between the bipolar membrane and cathode GDE, which could be further reduced to tens of micrometers upon refinement. The deconvolution of the potential drop from each individual component/process guides the pathways to higher energy efficiencies of CO2R at this platform. Significant changes in the agglomerate size and aspect ratio on the electrode before and after an 11 h test were revealed by nano-CT, suggesting reduced CO2 accessibility from electrode degradation. The versatility of this CO2R testing platform enables the ability to assess materials, components, and interactions at scales more in line with future devices.