Evaluating the Effects of Membranes, Cell Designs, and Flow Configurations on the Performance of Cu-GDEs in Converting CO₂ to CO

Abstract

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%.

Spectroelectrochemical Investigation of the Local Alkaline Environment on the Surface-Nanostructured Au for the Conversion of CO2 to CO

“…The electrochemical reduction of carbon dioxide (CO 2 ) is a promising approach for producing high-value-added chemicals with high efficiency and selectivity. − Due to the complex pathways of proton-coupled multi-electron-transfer reactions in CO 2 reduction, such comprehensive considerations of catalytic active sites, − effects of electrolytes, , and reaction systems − are required for selective catalyst design. Currently, the electron-transfer mechanisms involving the adsorption of CO 2 and generation/desorption of intermediates at the electrode–electrolyte interface are poorly understood.…”

Electrochemical CO2 conversion with a flow-through copper hollow fibre: A process parameter evaluation

“…Comparison of the results from Figure 4.1 with the performance of a flowthrough operated, flat-sheet GDE coated with the same copper particles that were used to prepare the fibres, [14] indicates that the fibres outperform the Cu-coated GDE in terms of ethylene, CO, formate and H2 partial current density. More importantly, the Cu-coated GDEs show a higher CO partial current density when operated in a flow-through fashion, compared to the same GDE operated in a flow-by configuration.…”

“…[8,[78][79][80][81] Removal of CO from the vicinity of the electrocatalyst reduces the local CO concentration and could limit the C-C coupling required for C2(+) production. [14] To study the effect of CO availability on the formation of C2(+) products, CO instead of CO2 was purged through the fibre. Acetate, ethylene and 1-propanol are observed as the main carbon-based products (Figure 4.2A).…”

“…For flat-sheet GDEs operated in a flow-through fashion it is reported that the GDEs suffer from a loss of performance as result of crystallization of the electrolyte in the GDE, [15] as well as detachment of catalytic particles from the support. [14][15] Operation of the copper hollow fibres for a duration of 24 hours showed a drop in the fibre's activity of about 10% in the first 7 hours of operation, followed by a stable operation during the remainder of the experiment. [17] During the research performed for this dissertation, the fibres are subjected to a maximum of 4 hours of electrolysis.…”

“…The third aspect determining the performance of a CO2 conversion electrocatalyst are its operating conditions. Parameters of interest are the imposed potential or current, the electrolyte type and concentration, [8] CO2 supply method [11,[14][15] and rate, [14,16] operating temperature and pressure, [8] the type of charge carrying membrane, [14] and the electrolyte flow rate. All these parameters affect the concentration of the reactants, intermediates and products at the vicinity of the electrocatalytic surface, and also influence the interaction of these species with the electrocatalytic surface.…”