Achieving high-performance electrochemical CO2 reduction using metal-polybenzimidazole coordination anion exchange membranes

Polybenzimidazole (PBI) membranes have attracted considerable attention in the energy sector for their outstanding performance. Nevertheless, their development is often restricted by low ionic conductivity. Coordinating metal ions (Fe 3+ ) with PBI can expand the spacing between polymer chains, creating nano-scale ion channels that enhance OH - transport within the membranes. In this study, we fabricated mPBI@Fe coordination membranes using the solution casting method. By varying the iron content, the ionic conductivity of these membranes was regulated. The findings revealed that the conductivity of OH - in these membranes was approximately 61.81 % higher than that of the original mPBI membranes, and they demonstrated excellent mechanical and thermal stability. Furthermore, compared to the commercial FAA-3–50 membrane, the [email protected] membrane demonstrates higher carbon monoxide (CO) fraction current density at a voltage of 3.0 V in the membrane-electrode assembly (MEA). Notably, at 50 mA cm -2 , the Faraday efficiency (FE CO ) of the [email protected] membrane electrodes remained above 95 %. Even after 870 min of electrolysis at 100 mA cm -2 , the FE CO decreased by only 1.57 %. These findings suggest promising prospects for advancing high-performance PBI-based membranes in electrochemical carbon dioxide reduction applications.