Abstract
AbstractThe 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.
Highlights
Electrochemical CO2 Reduction (ECO2R) has gained significant interest in the past decades for its prospective role in contributing to a net-zero CO2 society
This zero-gap configuration allows for a very low resistance between the electrodes, while the high concentration of CO2 helps in achieving the required high current densities. While this configuration is beneficial for scaling up this technology, it creates a reaction environment that is very different from what is found in a conventional H-cell where most catalyst screening
In this paper we examine the electrochemical operation of AgPd alloys at high current densities in an membrane electrode assemblies (MEAs) configuration to perform ECO2R
Summary
Electrochemical CO2 Reduction (ECO2R) has gained significant interest in the past decades for its prospective role in contributing to a net-zero CO2 society. Gaseous CO2 is directly fed to the electrode where it can diffuse through a porous transport layer to the catalyst surface This zero-gap configuration allows for a very low resistance between the electrodes, while the high concentration of CO2 helps in achieving the required high current densities. While this configuration is beneficial for scaling up this technology, it creates a reaction environment that is very different from what is found in a conventional H-cell where most catalyst screening. Attainable in GDE cells and MEAs, will significantly alter the local pH, changing the catalyst activity, selectivity, and durability, while requiring a different applied potential than for purely aqueous systems. The gas stream exiting the cathode was analysed every 10 min by an online Gas Chromatograph (GC) (Compact GC 4.0, GAS) with an internal N2 reference
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