Continuum Model for Optimizing CO Reduction Gas Diffusion Electrodes

Carbon monoxide electrolysis has the potential to unlock new routes to sustainable C2+ chemicals. Improvements to CO reduction (COR) gas diffusion electrodes (GDEs) are critical for advancing CO electrolysis cells, but a comprehensive understanding of COR GDEs remains elusive because of the complex interplay of physical and chemical processes under operating conditions and the difficulty of experimentally probing the heterogeneous environment of a GDE. In this study, we build a model for COR GDEs that includes fully coupled gas and ion transport and competing electrokinetic reactions. The transport and electrokinetic equations are solved in two dimensions to calculate critical COR figures of merit across multiple operating parameters including current density, flow rate, pressure, temperature, and electrochemically active surface area (ECSA). We validate our model by showing agreement with experimental data for steady-state CO electrolysis at various pressures and flow rates and then apply it to see how the figures of merit depend on the operating parameters over a wide range of values. We demonstrate that increasing the cell pressure above ambient and augmenting the ECSA of the catalyst are two effective strategies to improve cathode performance.