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

The CO2 reduction reaction (CO2RR) 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 CO2RR, attract tremendous research interest. However, for C-2 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 CO2RR. 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 C2H4 (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 CH2CHO*, CH3CHO*, and CH3CH2O*, which consequently modify the activity and selectivity (j(EtOH)/j(C2H4)) for the CO2RR. Moreover, AuCu/Cu-SCA also shows high durability with both the current density and FEEtOH being largely maintained for 24 h electrocatalysis.