Under certain economic conditions, electrocatalytic CO2 reduction has the potential to provide a carbon neutral route towards many currently-used chemicals and fuels, while allowing for the storage of large amounts of renewable energy that would otherwise be lost. Within the last few years, the field has gone from researching primarily catalyst development at lower current densities (&lt;10 mA/cm2), towards both fundamental and applied advances in catalysts, gas-diffusion layer and membrane electrode assemblies at higher current densities (&gt;200 mA/cm2). These advancements are important if we wish to use electrochemical CO2 reduction as a technology in the energy transition, which means commercialization by ~2030. Looking forward, greater research focus is now required on bridging the nano-, micro- and macro-scale phenomena occurring during CO2 electrolysis to optimize reaction selectivity, stability and efficiency, while quantifying system parameters such as a cell efficiency and CO2 utilization. In this work we briefly discuss the steps our lab is taking across a range of physical scales to advance CO2 electrolysis. Starting at the nanoscale, we are observing in-situ compositional and structural changes to catalysts deposited on gas-diffusion layers to better understand changes in H2, C1 and C2+ selectivity during &gt;200 mA/cm2 operation in KHCO3, KCl and KOH electrolytes. These studies are complemented by continuum transport models of the gas and electrolyte phases to understand both local conditions at the catalyst’s surface, and reactant/product homogeneity across larger gas-diffusion electrodes (&gt;5cm2) which influence the observed overall selectivity, particularly for copper-based electrodes. At the cell scale, experimental testing and modelling of different cell permutations are also performed to determine which of the configurations presented in literature are inherently stable from a catalyst, catholyte, anolyte and membrane perspective. While these studies vary in scale, a central focus of our lab’s work is on maintaining catalytic activity towards valuable products as production rate increases. This work exists within the broader framework of the ‘e-Refinery program’ at TU Delft, which is working to build a 100 kW demonstrator unit for electrochemical CO2 reduction on-site.

Next steps in electrochemical CO2 reduction: From catalysts to devices to systems

2019 Fall National Meeting

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