CO2-to-CO GDE-Flowcell From Lab-Test-Cell to Stack

While energy efficiency and conversion rates are not economically competitive yet,aqueous CO2-to-CO electrolysis is a promising approach for closing the carbon cycleand defossilize industrial processes [1]. Ag is already established as a stable andselective catalyst for this process, focus is therefore on raising the processperformance to a profitable level. A significant share of attention is drawn towardscontinuous flowcells operating with gas diffusion electrodes (GDE) [2]. This work isspecifically addressing the optimization of media flow and distribution in flow chambers.The internal media gaps are filled with different structures and their effects on theperformance are investigated. In the gas chamber the feed gas distribution over theGDE was controlled by implementing structures with various gas path architectures.The effect of these structures on the cell voltage and the conversion of CO2 to CO wasinvestigated at 100 mA/cm² in dependence of the CO2 feed gas supply. Aside of othereffects, an increase of the CO2 to CO conversion rate could be generated for reducedCO2 supply. Next to the gas chamber, the catholyte chamber was filled with a spacer,influencing the cell voltage and enhancing the process stability. The modifications inthe media gaps enabled in combination full force closure and provided an ionic andelectric contact over the full active cell area. Thus, a stackable flowcell architecture wasdeveloped, demonstrated in experiments with a two cell short stack.Literature:[1] CO2 Electrolysis to CO and O2 at High Selectivity, Stability and Efficiency UsingSustainion Membranes , Zengcai Liu, Journal of The Electrochemical Society, 165 (15)J3371-J3377, 2018[2] Continuous-flow electroreduction of carbon dioxide, B. Endrodia, Progress in Energyand Combustion Science 62, 201