Selective and Stable Ethanol Synthesis via Electrochemical CO2 Reduction in a Solid Electrolyte Reactor

Abstract

Electrochemical CO₂ reduction to ethanol faces challenges such as low selectivity, a product mixture with liquid electrolyte, and poor catalyst/reactor stability. Here, we developed a grain-rich zinc-doped Cu₂O precatalyst that presented a high ethanol Faradaic efficiency of over 40% under a current density of 350 mA·cm^–2. Our density functional theory (DFT) simulation suggested that Zn atoms inside the structure have a greater carbophilicity than the Cu atoms to help facilitate *CHCHO formation, a key reaction intermediate toward ethanol instead of other C₂ products. A high Faradaic efficiency ratio between ethanol and ethylene (FE_EtOH/FE_C2H4) reached 2.34 in the zinc-doped Cu₂O precatalyst, representing an over 4-fold improvement compared to bare Cu₂O precatalyst. By integrating this Cu-based catalyst into a porous solid electrolyte (PSE) reactor with a salt-managing design, we achieved stable ethanol production for over 180 h under a current density of 250 mA·cm^–2 while maintaining ethanol selectivity at ∼30%.