Synergistic H ⁺ leakage suppression in bipolar membrane electrodialysis via interfacial and proton‐blocking membrane for efficient CO ₂ capture

Bipolar membrane electrodialysis (BMED) is a promising platform for coupled brine valorization and CO 2 capture, yet its efficiency is limited by parasitic proton (H + ) leakage through the anion exchange membrane (AEM), which consumes hydroxide ions (OH − ) and increases energy demand. Here, we propose an integrated strategy combining a proton‐blocking AEM with in situ acid‐compartment neutralization to suppress the transmembrane proton driving force. The two approaches act synergistically, especially when low‐cost industrial carbide slag is used as the neutralizing agent. Compared with a conventional AEM (33.5% leakage), proton‐blocking membranes and acid neutralization individually reduce leakage to 16.2% and 22.8%, respectively, while their combination further lowers it to 10.3%. Therefore, the energy consumption for CO 2 capture decreases to 378.6 kJ·mol −1 CO 2 , with improved absorption performance. Furthermore, this work establishes a general design principle for electrochemical separations, highlighting the importance of regulating the interfacial chemical microenvironment to maximize ion‐exchange membrane performance.