Highly Selective Production of C2+ Oxygenates from CO2 in Strongly Acidic Condition by Rough Ag-Cu Electrocatalyst

Abstract

The acidic electrocatalytic conversion of CO₂ to multi-carbon (C₂₊) oxygenates is of great importance in view of enhancing carbon utilization efficiency and generating products with high energy densities, but suffering from low selectivity and activity. Herein, we synthesized Ag-Cu alloy catalyst with highly rough surface, by which the selectivity to C₂₊ oxygenates can be greatly improved. In a strongly acidic condition (pH=0.75), the maximum C₂₊ products Faradaic efficiency (FE) and C₂₊ oxygenates FE reach 80.4 % and 56.5 % at -1.9 V versus reversible hydrogen electrode, respectively, with a ratio of FE_{C2+ oxygenates} to FE_ethylene up to 2.36. At this condition, the C₂₊ oxygenates partial current density is as high as 480 mA cm^-2. The in situ spectra, control experiments and theoretical calculations indicate that the high generation of C₂₊ oxygenates over the catalyst originates from its large surface roughness and Ag alloying.

Keywords: Ag−Cu alloy; acidic electrocatalytic CO2 reduction; ethylene; multi-carbon oxygenates; selectivity.