Integrating Sorbents in CO2 Electroreduction: A Model System to Disentangle Layer Contributions in Membrane Electrode Assemblies

Abstract

Membrane electrode assemblies (MEAs) are crucial in high‐performance CO2 electrolysis, reducing iR losses and overcoming low solubility issues by supplying CO2 in the gas form. However, liquid anolyte permeation to the cathode causes salt precipitation, stability issues, and parasitic H2 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 CO2 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 CO2 supply to the cathode. Spectroscopic analysis provided mechanistic insights, demonstrating the model system's applicability to disentangle layer effects in integrated systems.