Efficient electrically powered CO₂-to-ethanol via suppression of deoxygenation

The carbon dioxide electroreduction reaction (CO₂RR) provides ways to produce ethanol but its Faradaic efficiency could be further improved, especially in CO₂RR studies reported at a total current density exceeding 10 mA cm⁻². Here we report a class of catalysts that achieve an ethanol Faradaic efficiency of (52 ± 1)% and an ethanol cathodic energy efficiency of 31%. We exploit the fact that suppression of the deoxygenation of the intermediate HOCCH* to ethylene promotes ethanol production, and hence that confinement using capping layers having strong electron-donating ability on active catalysts promotes C–C coupling and increases the reaction energy of HOCCH* deoxygenation. Thus, we have developed an electrocatalyst with confined reaction volume by coating Cu catalysts with nitrogen-doped carbon. Spectroscopy suggests that the strong electron-donating ability and confinement of the nitrogen-doped carbon layers leads to the observed pronounced selectivity towards ethanol.