Two Pathways for the Formation of Ethylene in CO Reduction on Single-Crystal Copper Electrodes

Abstract

Carbon monoxide is a key intermediate in the electrochemical reduction of carbon dioxide to methane and ethylene on copper electrodes. We investigated the electrochemical reduction of CO on two single-crystal copper electrodes and observed two different reaction mechanisms for ethylene formation: one pathway has a common intermediate with the formation of methane and takes place preferentially at (111) facets or steps, and the other pathway involves selective reduction of CO to ethylene at relatively low overpotentials at (100) facets. The (100) facets seem to be the dominant crystal facets in polycrystalline copper, opening up new routes to affordable (photo)electrochemical production of hydrocarbons from CO(2).

CO2 Reduction: From the Electrochemical to Photochemical Approach

“…Hori et al first showed that ethylene formation was favored on Cu (100) surface, whereas methane was the main hydrocarbon product on Cu (111) terraces 49. Similar results were also observed by Koper and co‐workers 50, 51. It is generally accepted that CO is a key intermediate in the formation of both methane and ethylene.…”

Face the Edges: Catalytic Active Sites of Nanomaterials

“…One more thing to note is that (211) facet of face center cubic (fcc) packing is not a close packing layer, and expose well‐packed edges of (111) facets. As for the reduction to ethylene, there may be two distinct mechanisms: one is through the formation of a surface‐adsorbed CO dimer at (100) facet at relatively low overpotentials,81 and the other has a methane intermediate at both (111) and (100) facets 82. To further corroborate the mechanism in real condition, in situ study is required 83.…”

RETRACTED ARTICLE: An overview of CO2 electroreduction into hydrocarbons and liquid fuels on nanostructured copper catalysts

“…Likely, this will limit the hydrogen evolution at higher overpotentials. A lower CO 2 concentration will decrease the formation of CO and formate along with a quick drop in product recovery of CO, likely due to its further high reaction rate for the formation of CH 4 and C 2 H 4 (74).…”

“…Koper et al (74) investigated the effect of local pH on the electroreduction of CO and CO 2 at Cu (111) and Cu (100) single-crystal electrodes. The electrochemical reduction of CO resulted in the formation of methane as a main product on Cu (111) and ethylene on Cu (100).…”

“…greater than 100 mA/cm 2 ) required for commercial applications are still lacking. These catalysts can be developed by deep and fundamental studies focusing on the reaction mechanism occurring on the catalyst during CO 2 reduction, an area in which only a few reports are presented (75)(76)(77).…”