Flooding-resistant gas diffusion electrode design for MEA-type CO2 electrolyzer

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) powered by renewable electricity offers a sustainable pathway for converting CO₂ into valuable products, presenting a promising strategy to mitigate atmospheric CO₂ concentrations. The design of gas diffusion electrodes (GDEs) plays a crucial role in enhancing the CO₂RR performance and stability in membrane-electrode assembly (MEA)-type electrolyzers. One of the primary challenges in industrializing CO₂RR technologies is the flooding of GDEs, which significantly reduces the stability of CO₂RR performance. Here, we design a flooding-resistant GDE by incorporation of macrochannels into GDE employing a nickel (Ni) foam substrate to mitigate GDE flooding and improve CO₂RR performance and stability. The macrochannels in Ni foam-based GDE ensure sufficient mass transfer of CO₂ to the catalyst layer and the discharge of electrolyte, thereby minimizing the GDE flooding. The Ni foam based-GDE exhibits significantly higher through-plane conductivity and gas permeability compared to conventional carbon paper-based GDEs and retains hydrophobicity even after prolonged operation. This GDE demonstrates higher CO current density (j_CO) and lower cell voltage, maintaining excellent stability with a high CO Faradaic efficiency (FE_CO) of 88.4 % over 50 h of continuous operation. These findings emphasize the importance of GDE designs with enhanced mass transfer capabilities to effectively address flooding challenges and improve the efficiency of CO₂RR in MEA-type electrolyzers.