Membrane Electrode Assembly for Electrocatalytic CO₂ Reduction: Principle and Application

Abstract

Electrocatalytic CO 2 reduction reaction (CO 2 RR) in membrane electrode assembly (MEA) systems is a promising technology. Gaseous CO 2 can be directly transported to the cathode catalyst layer, leading to enhanced reaction rate. Meanwhile, there is no liquid electrolyte between the cathode and the anode, which can help to improve the energy efficiency of the whole system. The remarkable progress achieved recently points out the way to realize industrially relevant performance. In this review, we focus on the principles in MEA for CO 2 RR, focusing on gas diffusion electrodes and ion exchange membranes. Furthermore, anode processes beyond the oxidation of water are considered. Besides, the voltage distribution is scrutinized to identify the specific losses related to the individual components. We also summarize the progress on the generation of different reduced products together with the corresponding catalysts. Finally, the challenges and opportunities are highlighted for future research.

Electrochemical reduction of carbon dioxide to multicarbon (C2+) products: challenges and perspectives

“…The emerging eCO 2 RR membrane electrode assembly (MEA) electrolyzers (or zero-gap reactors) contain a cathode and anode pressed tightly on both sides of the ion-exchange membrane, which effectively facilitates the mass transfer and promotes the activation of continuously delivered gaseous CO 2 at the membrane/cathode interface. 292,293 The eCO 2 RR electrolyzers involving anion exchange membranes (AEMs) have attracted extensive research attention. Positively charged functional groups on the polymer chain of the AEM facilitate anion transport from the cathode to the anode, enabling the CO 2 RR to occur in a basic environment.…”

Interaction of Cathode Interface Microenvironment and Anode Electrolyte in Zero-Gap Electrolyzer for CO2 Conversion

“…6 MEA (or zero-gap electrolyzer) was originally developed for fuel cells and low-temperature water electrolysis, and is now also being employed for carbon dioxide reduction. 7 The anode and cathode of the zero-gap electrolyzer cell are tightly pressed against both sides of the membrane, forming a sandwich-like structure of anode-membrane-cathode. By adjusting the membrane's conductivity and thickness, the ohmic resistance can be greatly reduced.…”

Thermodynamic and Economic Assessments of Electrochemical CO2 Conversion to Dimethyl Ether: Trade-off between Hydrogen Gas and Water Vapor as a Proton Source

“…This type of electrolyzer differs from a traditional H-cell by having a gas diffusion electrode (GDE) that allows for direct feeding of CO 2 to the catalyst surface, minimizes mass transport losses, and enhances product selectivity. 33 There have been extensive studies on MEAs exploring electrolyte effects, GDE properties, membranes, specifically anion exchange membranes (AEM) and bipolar membranes (BPM), and optimization techniques such as iR compensation and CO 2 flow rate. 34−41 In addition, operating zero-gap electrolyzers consisting of an MEA in a gaseous phase without liquid electrolytes enables the production of primarily gaseous products, minimizing separation and purification steps.…”