Strategies and Challenges of Utilizing Cation Effects in Membrane Electrode Assemblies for CO₂ Reduction

Electrocatalytic CO₂ reduction in membrane electrode assembly (MEA) systems is a promising technology, enabling direct CO₂ transport to the catalyst layers and reducing ohmic resistance. While electrolyte cations are demonstrated to effectively enhance the rate and the selectivity of electrochemical reduction of CO₂, their implementation in electrolyte-free MEA electrolyzers faces significant challenges. This concept review examines key strategies for utilizing cations in MEA configurations, categorizing them into three methods: 1) incorporation of alkali metal cations into catalyst layers, 2) integration of organic cations into the cathode, and 3) mitigation of salt precipitation on the gas diffusion layers. By summarizing the challenges and proposed strategies, this review aims to provide guidance for the development of more efficient cation utilization approaches and future research in MEA-based CO₂ reduction systems.