Continuous electrocatalytic conversion of CO2 to ethanol with high selectivity using advanced MOF-based electrodes

The current climate emergency has intensified interest in technologies aimed at mitigating greenhouse gas emissions, particularly carbon dioxide (CO 2 ). Among these, CO 2 capture, storage, and utilization (CCUS) technologies are gaining increasing importance. This work focuses on the electrochemical conversion of CO 2 into value-added products, particularly alcohols, due to their economic relevance, exploring metal-organic frameworks (MOFs) as catalytic cathode materials. Cu-MOF-74, Cu-BTC MOF, Mg-MOF-74, and Ni-MOF-74 were evaluated as cathodic catalysts for the electrocatalytic reduction of CO 2 using 0.5 M KHCO 3 as the electrolyte. Ni-MOF-74 showed the best performance toward CH 3 OH, achieving a Faradaic Efficiency (FE) of 15.31% at −1.5 V vs. Ag/AgCl and an Energy Consumption (EC) of 2.35·10 3 kWh·kmol −1 . C 2 H 5 OH was also obtained simultaneously, reaching a FE of 31.12% and an EC of 4.63·10 3 kWh·kmol −1 at −1.3 V vs. Ag/AgCl. Subsequent experiments evaluated system efficiency by coupling these MOFs with a non-precious metal-based anode, a Ni Fe foam. Mg-MOF-74 and Ni-MOF-74 were used in paired experiments, as they showed higher activity than the Cu-based MOFs toward alcohol production. The highest CH 3 OH FE (9.77%) was achieved using Ni-MOF-74 at −1.3 V, reaching a promising FE of 84.55% and an EC of 512.91 kWh·kmol −1 . Although overall EC decreased in the full-cell configuration, a shift in selectivity from CH 3 OH to C 2 H 5 OH was observed.