Packed Bed Membraneless Electrolyzers for High CO2 Conversion per Pass

Electrochemical CO₂ reduction reaction (CO2RR) provides a promising route to convert excess CO₂ emissions into value-added fuels and chemicals using renewable electricity. Although CO₂ electrolyzers with high selectivity for certain products at industrially relevant current density can be reached, a major remaining challenge is to achieve a high conversion per pass. At high current densities, the local alkalinity created by CO2RR limits the high CO₂ conversion per pass due to the CO₂ consumption by the produced hydroxyls. In this work, we present novel and potentially low-cost packed bed membraneless electrolyzers (PBMEs) to achieve high CO₂ conversion per pass. The new reactors have multiple pairs of electrodes to boost the CO₂ conversion per pass and they are ideally suited for maintaining favorable pH between the electrodes so that carbonate formation can be minimized. Basic operating principles have also been modeled to help understand the current distribution of the porous electrodes.