Electrochemical reduction of carbon dioxide at various series of copper single crystal electrodes

Abstract

Abstract Electrochemical reduction of carbon dioxide was studied with various series of copper single crystal electrodes in 0.1 M KHCO3 aqueous solution at constant current density 5 mA cm−2; the electrodes employed are Cu(S)-[n (1 0 0)×(1 1 1) ], Cu(S)-[n (1 0 0)×(1 1 0) ], Cu(S)-[n (1 1 1)×(1 0 0) ], Cu(S)-[n (1 1 1)×(1 1 1) ] and Cu(S)-[n (1 1 0)×(1 0 0) ]. The electrodes based on (1 0 0) terrace surface give ethylene as the major product. The ethylene formation is further promoted by the introduction of (1 1 1) or (1 1 0) steps to the (1 0 0) basal plane. The highest C2H4 to CH4 formation ratio amounts to 10 in terms of the current efficiency for the (7 1 1) (=4(1 0 0) − (1 1 1)) surface as compared with the value 0.2 for the (1 1 1) electrode. The n(1 1 1)−(1 1 1) surfaces favor the formations of acetic acid, acetaldehyde and ethyl alcohol with the increase of the (1 1 1) step atom density. CH4 formation at the n(1 1 1)−(1 1 1) electrodes decreases with the increase of the (1 1 1) step atom density. The n(1 1 1)−(1 0 0) surfaces give higher gaseous products; the major product is CH4 with lower fraction of C2+ compounds.