(111) Facet-oriented Cu 2 Mg Intermetallic Compound with Cu 3 -Mg Sites for CO 2 Electroreduction to Ethanol with Industrial Current Density.

The efficient ethanol electrosynthesis from CO 2 is challenging with low selectivity at high CO 2 electrolysis rates, due to the competition with H 2 and other reduction products. Copper-based bimetallic electrocatalysts are potential candidates for the CO 2 -to-ethanol conversion, but the secondary metal has mainly been focused on active components (such as Ag, Sn) for CO 2 electroreduction, which also promote selectivity of ethylene or other reduction products rather than ethanol. Limited attention has been given to alkali-earth metals due to their inherently active chemical property. Herein, we rationally synthesized a (111) facet-oriented nano Cu 2 Mg (designated as Cu 2 Mg(111)) intermetallic compound with high-density ordered Cu 3 -Mg sites. The in situ Raman spectroscopy and density function theory calculations revealed that the Cu 3 - δ $_{^{\rm{{\rm \delta} }} }$ - -Mg - δ $_{^{\rm{{\rm \delta} }} }$ + active sites allowed to increase *CO surface coverage, decrease reaction energy for *CO-CO coupling, and stabilize *CHCHOH intermediates, thus promoting the ethanol formation pathway. The Cu 2 Mg(111) catalyst exhibited a high FE C2H5OH of 76.2±4.8 % at 600 mA⋅cm -2 , and a peak value of |j C2H5OH | of 720±34 mA⋅cm -2 , almost 4 times of that using conventional Cu 2 Mg with (311) facets, comparable to the best reported values for the CO 2 -to-ethanol electroreduction.