A First-Principles Study on the Reaction Mechanisms of Electrochemical CO2 Reduction to C1 and C2 Products on Cu(110)

The mechanism of the electrochemical CO2 reduction reaction on a Cu(110) surface has yet to be fully revealed. In this work, based on first-principles calculations, we investigate the mechanisms of the CO2 reduction reaction to produce C1 (including one C atom) and C2 (including two C atoms) products on a Cu(110) surface. The results show that CH4 and C2H5OH are the main C1 and C2 products on the Cu(110) surface, respectively. CH4 is produced along the pathway CO2 → COOH* → CO* → CHO* → CH2O* → CH3O* → CH4. C2H5OH is produced via the C-C coupling pathway between CO* and CH2O* intermediates, which is the key reaction step. This is because CO* and CH2O* coupling to CO-CH2O* has the lowest barrier among the CHxO* (x = 0–2) coupling pathways. Therefore, it is the most likely C-C coupling pathway. Further, CO-CH2O* is gradually hydrogenated to C2H5OH along the following pathway: CO-CH2O* → CHO-CH2O* → CHOH-CH2* → CH2OH-CH2* → CH2OH-CH3* → C2H5OH.