Synthesis of C3 and C5 Oxygenates from the Co-electrolysis of Carbon Monoxide and Acetylene on a Cu–Pd Catalyst

Abstract

The electroreduction of CO₂ (CO₂RR) and CO (CORR) using renewable electricity provides a sustainable route for decarbonizing chemical manufacturing. However, boosting the production of multi-carbon oxygenates remains challenging. Herein, we report that the co-electroreduction of CO and acetylene (C₂H₂) on an oxide-derived Cu₅Pd (OD-Cu₅Pd) catalyst at −1.1 V vs SHE achieves ∼130× higher production of C₃ oxygenates, such as 1-propanol, propionaldehyde, and allyl alcohol, compared to CORR alone. Seven C₅ oxygenates, including 3-pentanone, cyclopentanone, and 1-pentanol, were further identified, none of which have been previously observed in either CORR or CO₂RR. The remaining balance of the products was mainly ethylene and 1,3-butadiene. The addition of Pd to Cu enhances both CO and C₂H₂ adsorption, facilitates C–C coupling, and significantly improves the oxygenate yields. At −1.1 V vs SHE, the production rates of C₃ oxygenates on OD-Cu₅Pd catalyst were doubled, while that of C₅ oxygenates increased by ∼6-fold, as compared to that on unmodified OD-Cu. The oxygenate production rates were further optimized by tuning the applied potential, feedstock stoichiometry, and temperature. Mechanistic studies indicate that the C₃ oxygenates and the C₅ oxygenates with mid-chain oxygen atoms form via CO and C₂H₂ coupling, while the C₅ oxygenates with terminal oxygen atoms stem from CO reacting with 1,3-butadiene, a C₂H₂ reduction intermediate. These results present a promising and sustainable strategy for the electrosynthesis of long-chain oxygenates.