Evaluating the Effects of Membranes, Cell Designs, and Flow Configurations on the Performance of Cu-GDEs in Converting CO₂to CO

In this study, we evaluate the effect of cell configuration parameters on electrochemical reduction of CO2 using Cu gas-diffusion electrodes (Cu-GDEs), including the use of proton- or anion-exchange membranes, the CO2 flow configuration, and the Nafion content used in the ink formulation to prepare the Cu-GDEs. Using a cell configuration (i) containing a Sustainion membrane, (ii) allowing a liquid flow of catholyte and anolyte, and (iii) providing convective supply of CO2 in a flow-through mode, outstanding faradaic efficiencies toward carbon monoxide (FECO = ∼85%, at -0.88 V vs RHE, and 50 mA·cm-2) were obtained. We attribute this performance to an efficient desorption and transport of CO to the exit of the reactor, in agreement with the remarkably low FE toward ethylene at the applied electrochemical potentials. Most importantly, in this configuration and optimizing the Nafion content in the ink formulation to 10 wt %, cell performance could be maintained for at least 10 h of continuous operation at the high FECO of ∼85%.