Integrating Sorbents in CO 2 Electroreduction: A Model System to Disentangle Layer Contributions in Membrane Electrode Assemblies

Abstract Membrane electrode assemblies (MEAs) are crucial in high‐performance CO 2 electrolysis, reducing iR losses and overcoming low solubility issues by supplying CO 2 in the gas form. However, liquid anolyte permeation to the cathode causes salt precipitation, stability issues, and parasitic H 2 evolution, hindering industrial implementation. Full gas‐phase operation could mitigate these problems, but a model system to study gas‐phase concepts is lacking. This study presents a planar bimetallic interdigitated electrode array (BIDEA) as a model system, using a sorbent electrolyte for CO 2 electroreduction as a case study. The simplified system, combined with numerical models, reveals key process limitations, such as diffusion over the material and the role of sorption kinetics in limiting CO 2 supply to the cathode. Spectroscopic analysis provided mechanistic insights, demonstrating the model system's applicability to disentangle layer effects in integrated systems.