Cation-Driven Increases of CO(2) Utilization in a Bipolar Membrane Electrode Assembly for CO(2) Electrolysis

[Image: see text] Advancing reaction rates for electrochemical CO(2) reduction in membrane electrode assemblies (MEAs) have boosted the promise of the technology while exposing new shortcomings. Among these is the maximum utilization of CO(2), which is capped at 50% (CO as targeted product) due to unwanted homogeneous reactions. Using bipolar membranes in an MEA (BPMEA) has the capability of preventing parasitic CO(2) losses, but their promise is dampened by poor CO(2) activity and selectivity. In this work, we enable a 3-fold increase in the CO(2) reduction selectivity of a BPMEA system by promoting alkali cation (K(+)) concentrations on the catalyst’s surface, achieving a CO Faradaic efficiency of 68%. When compared to an anion exchange membrane, the cation-infused bipolar membrane (BPM) system shows a 5-fold reduction in CO(2) loss at similar current densities, while breaking the 50% CO(2) utilization mark. The work provides a combined cation and BPM strategy for overcoming CO(2) utilization issues in CO(2) electrolyzers.