Assessing Silver Palladium Alloys for Electrochemical CO₂ Reduction in Membrane Electrode Assemblies

The field of electrochemical CO₂ reduction has been transitioning to industrially relevant scales by changing the architecture of the electrochemical cells and moving away from the traditional aqueous H-cells to membrane electrode assemblies (MEA). The reaction environments in MEAs vary drastically from that of aqueous H-cells, which could result in significantly different catalytic activity. In this paper, we test AgPd alloys, one of the most promising CO producing catalysts reported, at industrially relevant scales (50 to 200 mA/cm²) in a MEA configuration. We report that, with increasing Pd composition in the electrode, the CO selectivity reduces from 99 % for pure Ag to 73 % for pure Pd at 50 mA/cm². The MEA configuration helps attain a high CO partial current density of 123 mA/cm². We find that catalytic activity reported in aqueous H-Cells does not translate at higher current densities and that cell architecture must play an important role in benchmarking catalytic activity.