Presentation Date: Feb 14, 2026
AGSA Abstract
Product crossover through ion-exchange membranes represents a critical barrier preventing commercial implementation of electrochemical CO₂ reduction to liquid chemicals. This work addresses this fundamental limitation through development and optimization of a novel dual-membrane electrolyzer architecture enabling near-complete product retention. Conventional membrane electrode assemblies were systematically evaluated for liquid product formation using copper-tin and copper-selenium catalysts. Despite achieving competitive Faradaic efficiencies—ethanol at 51.5%, formate at 69.6%, acetate at 48%—product analysis revealed catastrophic crossover losses of 82–96% to the anode compartment. Ethanol migrating through membranes undergoes oxidation while experiencing extreme dilution to below 0.05 wt%, rendering downstream separation economically prohibitive. Alternative membrane chemistries all exhibited crossover exceeding 80%, confirming single-membrane architectures fundamentally cannot prevent neutral molecule transport. A flowing electrolyte-direct CO₂ electrolyzer featuring dual-membrane configuration was developed with an intermediate flowing electrolyte channel positioned between anion-exchange and cation-exchange membranes. This design reduced ethanol crossover from 94% to less than 2%, enabling collection at 8.7 wt% concentration with 63% Faradaic efficiency—representing 170-fold improvement compared to conventional systems. Systematic optimization identified the 2-channel configuration (0.5 mm thickness) operating at 20–40 cm min⁻¹ velocity as optimal, generating high linear velocities at moderate volumetric flow rates for effective convection-dominated transport. Operating with water in the intermediate channel enabled direct formic acid (52.4%) and acetic acid (28.6%) production with 99.9% collection efficiency, eliminating both alkali consumption and downstream acidification requirements. Fluid dynamics analysis confirms the architecture fundamentally shifts transport from diffusion-limited to convection-dominated, providing a robust solution to product crossover limitations.
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