Energy- and carbon-efficient CO2/CO electrolysis to multicarbon products via asymmetric ion migration-adsorption

Carbon dioxide/monoxide (CO2/CO) electrolysis provides a means to convert emissions into multicarbon products. However, impractical energy and carbon efficiencies limit current systems. Here we show that these inefficiencies originate from uncontrolled gas/ion distributions in the local reaction environment. Understanding of the flows of cations and anions motivated us to seek a route to block cation migration to the catalyst surface-a strategy we instantiate using a covalent organic framework (COF) in bulk heterojunction with a catalyst. The pi-conjugated hydrophobic COFs constrain cation (potassium) diffusion via cation-pi interactions, while promoting anion (hydroxide) and gaseous feedstock adsorption on the catalyst surface. As a result, a COF-mediated catalyst enables electrosynthesis of multicarbon products from CO for 200 h at a single-pass carbon efficiency of 95%, an energy efficiency of 40% and a current density of 240 mA cm(-2).

Automated summary

Carbon dioxide/monoxide (CO2/CO) electrolysis has the potential to convert emissions into multicarbon products, but current systems suffer from low energy and carbon efficiencies. In this study, the researchers identified uncontrolled gas/ion distributions as the source of these inefficiencies and developed a strategy to block cation migration to the catalyst surface using a covalent organic framework (COF). The COF-mediated catalyst achieved a single-pass carbon efficiency of 95%, an energy efficiency of 40%, and a current density of 240 mA cm(-2) during 200 hours of electrosynthesis of multicarbon products from CO.