Elucidation of Critical Catalyst Layer Phenomena toward High Production Rates for the Electrochemical Conversion of CO to Ethylene

High Resolution Image Download MS PowerPoint Slide This work utilizes EIS to elucidate the impact of catalyst–ionomer interactions and cathode hydroxide ion transport resistance ( R CL, OH – ) on cell voltage and product selectivity for the electrochemical conversion of CO to ethylene. When using the same Cu catalyst and a Nafion ionomer, varying ink dispersion and electrode deposition methods results in a change of 2 orders of magnitude for R CL, OH – and ca. a 25% change in electrode porosity. Decreasing R CL, OH – results in improved ethylene Faradaic efficiency (FE), up to ∼57%, decrease in hydrogen FE, by ∼36%, and reduction in cell voltage by up to 1 V at 700 mA/cm 2 . Through the optimization of electrode fabrication conditions, we achieve a maximum of 48% ethylene with >90% FE for non-hydrogen products in a 25 cm 2 membrane electrode assembly at 700 mA/cm 2 and <3 V. Additionally, the implications of optimizing R CL, OH – is translated to other material requirements, such as anode porosity. We find that the best performing electrodes use ink dispersion and deposition techniques that project well into roll-to-roll processes, demonstrating the scalability of the optimized process.