Tailoring the *CO and *H Coverage for Selective CO2 Electroreduction to CH4 or C2H4

Abstract

In the electrochemical CO₂ reduction reaction (CO₂RR), the coverages of ^*CO and ^*H intermediates on a catalyst surface are critical for the selective generation of C₁ or C₂ products. In this work, we have synthesized several Cu_xZn_yMn_z ternary alloy electrocatalysts, including Cu₈ZnMn, Cu₈Zn₆Mn, and Cu₈ZnMn₂, by varying the doping compositions of Zn and Mn, which are efficient in binding ^*CO and ^*H adsorbates in the CO₂ electroreduction process, respectively. The increase of ^*H coverage allows to promotion of the CH₄ and H₂ formation, while the increase of the ^*CO coverage facilitates the production of C₂H₄ and CO. As a result, the Cu₈ZnMn catalyst presented a high CO₂-to-CH₄ partial current density (-418 ± 22 mA cm^-2) with a Faradaic efficiency of 55 ± 2.8%, while the Cu₈Zn₆Mn catalyst exhibited a CO₂-to-C₂H₄ partial current density (-440 ± 41 mA cm^-2) with a Faradaic efficiency of 58 ± 4.5%. The study suggests a useful strategy for rational design and fabrication of Cu electrocatalysts with different doping for tailoring the reduction products.

Keywords: CO2 reduction; Faradaic efficiency; hydrocarbons; intermediate coverage; ternary alloy.