A Guide to the Design and Testing of a Lab-Scale Flow Cell CO₂ Electrolyzer with Gas-Diffusion Electrodes

The CO2 electrolyzer is a pivotal technology for enabling the electrification and decarbonization of the chemical industry. Significant advancements in CO2 electrolysis have been achieved through research focusing on catalysts, gas-diffusion electrodes (GDEs), and system design. While several guides on electroanalytical techniques and electrolyzer operation exist, a comprehensive guide addressing cell design considerations and their relationship to experimental process parameters is still needed. Herein, we present general guidelines for designing and testing a lab-scale flow cell (F-cell) electrolyzer for CO2 electrolysis using GDEs. The process begins with fundamental design principles, followed by prototyping and materials selection, and culminates in manufacturing and assembly instructions. This electrolyzer is benchmarked using commercial Ag- and Cu-based catalysts for CO2 conversion to CO and C-C products, respectively, and several diagnostic tools are demonstrated for characterizing GDE performance in a F-cell electrolyzer. Furthermore, we show that the electrolyzer is compatible with various GDE substrates, including carbon-paper-based and polymer-membrane-based gas-diffusion layers as well as metal mesh electrodes. We anticipate that the principles and guidelines presented here will assist researchers entering the field of CO2 electrolysis and inspire innovative cell designs tailored to their specific research needs.