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 (jEtOH /jC2H4 ) 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 (jEtOH /jC2H4 ) for the CO2 RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FEEtOH being largely maintained for 24 h electrocatalysis.