Developing a Suitable Anion Exchange Layer Structure for Pure–Water Fed Bipolar Membrane CO ₂ Electrolysis

Anion exchange membrane‐based CO 2 electrolyzers powered by renewable energy provide a promising pathway for a sustainable CO 2 ‐to‐CO conversion. However, they suffer from CO 2 crossover via the formation of (bi)carbonates, limiting carbon utilization to 50%, and electrolyte‐driven salt precipitation, which shortens device lifetime. A forward‐biased bipolar membrane addresses these issues by operating with pure water and regenerating CO 2 at the bipolar junction. Nevertheless, instability of the bipolar interface, lower faradaic efficiency, and high cell potential remain open challenges. Here, we present a bipolar membrane incorporating a porous anion exchange layer to facilitate CO 2 release out of the bipolar junction. Two bipolar membrane configurations are compared with a porous or dense anion exchange layer deposited either onto a silver‐based gas diffusion electrode or onto the cation exchange membrane. Porous anion exchange layer‐coated gas diffusion electrodes achieved enhanced stability, lower cell potentials, and partial current densities for CO up to 214 mA cm −2 at 3.25 V. Implementation of this bipolar membrane architecture reduces CO 2 crossover by at least 80% compared with an anion exchange membrane‐based electrolyzer, although CO 2 losses to the anode persist, highlighting the need for further optimization. These findings establish porous anion exchange layer‐coated gas diffusion electrodes as a promising strategy for advancing bipolar membrane CO 2 electrolysis.