Dual‐Layer Polymer Coating for Selective CO ₂ Reduction in Acidic Media

CO 2 electroreduction offers a promising pathway for converting carbon emissions into valuable chemicals. Common neutral and alkaline electrolytes are usually associated with salt precipitation and carbon crossover that limit CO 2 utilization efficiency, making acidic media an attractive alternative. However, the inherent low kinetics of CO 2 reduction under acidic environments suppresses both C 2+ Faradaic efficiency and single‐pass conversion efficiency. Here, we develop a dual‐layer polymer coating strategy to enhance both CO 2 utilization and multi‐carbon product formation activity. The outer Nafion‐carbon thin layer selectively suppresses the transport of H + to create a locally alkaline environment, while the inner polytetrafluoroethylene layer on Cu catalysts facilitates CO 2 transport through its hydrophobic features. The dual‐layer polymer‐coated gas diffusion electrode achieves an 80% single‐pass conversion efficiency at a current density of 600 mA cm −2 with a high C 2+ Faradaic efficiency of 85.7%, which is more than 3‐fold higher than that of bare Cu catalysts. Our dual‐layer polymer coating design demonstrates significant promise for practical CO 2 electroreduction in acidic media.