Gas Diffusion Electrodes (GDEs) for Carbon Dioxide (CO₂) Reduction in Microfluidic Cells: Towards a Fluid Dynamics Assisted Rational Design

The electrochemical reduction of carbon dioxide (CO 2 ) for the generation of multicarbon (C 2+ ) products with high commercial value—e.g., ethanol and ethylene—is gaining growing interest due to the successful implementation of laboratory scale technologies that can reach high current densities (>500 mA cm −2 ) and Faradaic efficiencies (>60%), using a simplified approach in terms of configuration and cost. This is the case of microfluidic cells, low-temperature electrochemical flow systems which optimal operation sustains on the enhancement of the mass and charge transfer phenomena taking place at the gas diffusion electrode (GDE) | aqueous electrolyte interface where CO 2 molecules are selectively transformed at the surface of the catalyst layer. This work presents an up-to-date overview of materials and operational conditions for microfluidic-type systems, providing significant enlightenment on the effects that the phenomena occurring at the GDE | electrolyte interface have over the CO 2 reduction reaction kinetics towards the generation of C 2+ products. It is shown that the integration of computational methods (particularly, density functional theory and computational fluid dynamics) into conventional experimental approaches is an effective strategy to elucidate the reaction mechanisms and mass/charge transfer trends determining the enhanced design of GDEs and the GDE | electrolyte interface.