Enhancing CO2 Electroreduction to Ethylene in Acidic Solution by Optimizing Cation Configuration on the Cu Surface.

Abstract

The electroreduction of CO₂ to C₂H₄ offers a promising avenue for advancing carbon neutrality and promoting sustainable chemical manufacturing. In acidic environments, while long-term operational stability and CO₂ utilization efficiency are enhanced, the formation of C-C bonds is hindered due to the weak adsorption of *CO intermediates and the competing hydrogen evolution reaction (HER). Theoretical studies suggest that K⁺ cations with reduced bound water content can strengthen the adsorption of the critical *CO intermediate, and that elevated K⁺ concentrations on the Cu electrode surface significantly facilitate CO₂ electroreduction to C₂H₄. In this work, a catalyst termed Cu_TEA was developed by strategically modifying the Nafion ionomer distribution within the catalyst layer. This structural adjustment effectively lowers the bound water associated with K⁺ cations and concurrently elevates the surface concentration of K⁺ on the Cu electrode, thereby promoting C-C coupling for C₂H₄ formation while suppressing HER. Consequently, Cu_TEA achieves a Faradaic efficiency of 70.2% for C₂H₄ production, accompanied by a high partial current density of 561.6 mA cm^-2 in an acidic electrolyte (pH = 1).