A continuous flow reactor for tubular gas diffusion electrodes

Abstract

Tubular gas diffusion electrodes (GDEs) have been mainly characterized in H-cell environments without consideration of changing flow conditions and scale-up possibilities. In this study, a continuous flow reactor for tubular GDEs is presented, which allows for different electrode configurations and manipulation of flow conditions to control mass transfer. 3D printed copper GDEs are employed for CO2 electroreduction while membrane electrode assemblies (MEAs) from stainless steel electrodes are used on the anode side. We demonstrate the impact of the gas supply in either flow-through or flow-by mode on catalyst performance. Flow-through mode yields a variety of typical products, such as CO, HCOOH, CH4 and C2H4. Flow-by mode results in mainly CH4, which we link to a higher surface coverage of reaction intermediates with diffusion as the governing transport mechanism in flow-by operation. Additionally, a hybrid porosity GDE is introduced that combines different functional domains in one electrode for improved CO2 mass transfer. Microcomputed tomography confirms the successful realization of these domains in close proximity to each other. With the presented approach, we aim to highlight the importance of the reaction environment for an effective scale-up of tubular concepts in CO2 electroreduction and many other electrochemical applications.