Selective Electrochemical Production of Ethylene from Bicarbonate Solution.

Abstract

Carbon dioxide (CO₂) electroreduction directly from a reactive carbon solution (e.g., (bi)carbonate) provides a promising approach for integrating CO₂ capture and conversion. Compared to CO₂ conversion in gas-fed systems, this system typically suffers from low Faradaic efficiency (FE), especially for multicarbon (C₂₊) products. Here, we report an engineered material structuring to selectively produce C₂₊ products 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, porosity, and surface oxidation of copper (Cu) mesh catalysts, as well as catholyte composition, we achieved a maximum C₂H₄ FE of 39% and total C₂₊ FE over 55% at 150 mA cm^-2 with a 240 µm thick Cu mesh. The system is also stable for over 160 h at 100 mA cm^-2 with maintained C₂H₄ FE over 20%. Our electrolysis system converts bicarbonate to C₂₊ with over 90% CO₂ utilization efficiency, reducing regeneration and separation costs. Optimizing catalyst pore structure, and copper surface oxide is a key to maximizing C₂H₄ production from bicarbonate solutions.