AuCu Alloy Nanoparticle Embedded Cu Submicrocone Arrays for Selective Conversion of CO2 to Ethanol

Abstract

The CO₂ reduction reaction (CO₂ RR) driven by renewable electricity represents a promising strategy toward alleviating the energy shortage and environmental crisis facing humankind. Cu species, as one type of versatile electrocatalyst for the CO₂ RR, attract tremendous research interest. However, for C₂ products, ethanol formation is commonly less favored over Cu electrocatalysts. Herein, AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu-SCA) are constructed as an active, selective, and robust electrocatalyst for the CO₂ RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency (FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited (16 ± 4%) in KHCO₃ aqueous solution. The ratio between partial current densities of EtOH and C₂ H₄ (j_EtOH /j_C2H4 ) can be tuned in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts. The combined experimental and theoretical calculation results identify the importance of Au in modifying binding energies of key intermediates, such as CH₂ CHO*, CH₃ CHO*, and CH₃ CH₂ O*, which consequently modify the activity and selectivity (j_EtOH /j_C2H4 ) for the CO₂ RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FE_EtOH being largely maintained for 24 h electrocatalysis.

Keywords: AuCu alloys; CO2 reduction; Cu submicrocone arrays; ethanol.