In this work, we report an engineered material structuring to selectively produce C2+ products with high FE directly from a N2-saturated bicarbonate solution. Multiphysics modeling studies reveal the critical role of local current density distribution and the spatio-selective evolution of C2+ products, which is favored in thinner catalysts (240 µm thickness). By jointly tailoring catalyst configuration and mass transport in bicarbonate electroreduction-adjusting the thickness (ranges from 1040 µm to 240 µm), porosity, and surface oxidation of Cu mesh catalysts, as well as catholyte composition-we achieved a maximum ethylene FE of 39% and total C2+ product FE over 55% at 150 mA/cm2 with a 240 µm thickness of Cu mesh. The system is also stable for over 160 hours at 100 mA/cm2 with maintained ethylene FE over 20%. The direct (bi)carbonate electrolysis system converts bicarbonate into C2+ products with a CO2 utilization efficiency of more than 90%, thereby reducing potential expenses associated with regeneration and separation. We determine that optimizing the catalyst pore structure, which governs the diffusion of the bicarbonate solution, and the copper surface oxide layer, which determines product FE, is critical to maximizing ethylene production from bicarbonate solutions.
Keywords: Bicarbonate conversion, integrated capture and conversion, electrode engineering, CO2 reduction.
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