Combined Simulation and Experimental Study of Electrolysis Flow Cell for Continuous CO_2 Conversion

摘要

Electrochemical carbon dioxide reduction reaction (CO_2RR) is a promising strategy to sequester CO_2 while synthesizing valuable chemicals and utilizing intermittent renewable energy supply from solar and wind energy. Electrolysis is often studied in H-cells that are composed of planar electrodes immersed in an aqueous electrolyte, which have severely limited mass transport across the electrolyte and hydrodynamic boundary layer. To avoid these limitations alkaline flow cells with a gas diffusion electrode (GDE) operated in a flow-by mode are sometimes used to achieve more realistic conditions. Although they provide higher current densities (CD) and energy efficiencies (EE), they suffer from carbonate salt precipitation in the stagnant pores of the GDE, moreover in KOH electrolyte CO_2 is parasitically converted to bicarbonate. To remedy the latter problem neutral electrolytes, such as K_2SO_4 or KHCO_3, can replace alkaline electrolytes, but these have so far demonstrated low EE due to high ohmic resistance and overpotentials in the GDE.