Asymmetric CO–CHO Coupling over Pr Single-Atom Alloy Enables Industrial-Level Electrosynthesis of Ethylene

The electrocatalytic conversion of carbon dioxide (CO₂) to ethylene (C₂H₄) holds great promise for sustainable chemical synthesis, yet achieving industrially relevant production rates remains a significant challenge. Through computational screening, we have identified a praseodymium (Pr) single-atom alloy embedded in a copper (Cu) catalyst (Pr@Cu) that exhibits superior CO₂ activation and a remarkably low energy barrier for asymmetric *CO-*CHO coupling, primarily by facilitating the *CHO intermediate formation. Our optimized catalyst, Pr@Cu-2 (6 wt % Pr), achieves a C₂H₄ Faradaic efficiency (FE) of 64.2% at -1.6 V versus the reversible hydrogen electrode (RHE) under a high current density of 1200 mA cm^-2 in the CO₂ reduction reaction (CO₂RR). Furthermore, when integrated into a 100 cm² membrane electrode assembly (MEA) electrolyzer, Pr@Cu-2 demonstrates robust performance, maintaining a continuous C₂H₄ production rate of 21.3 mL min^-1 at 20 A for over 200 h. This work provides fundamental insights into the role of Pr single-atom alloys in the CO₂RR and highlights their potential for scalable C₂H₄ electrosynthesis.