Electrochemical synthesis of propylene from carbon dioxide on copper nanocrystals

The electrochemical reduction of carbon dioxide to propylene requires multiple C–C coupling steps and the transfer of 18 electrons, posing kinetic and thermodynamic barriers. Now the electrosynthesis of propylene from carbon dioxide using copper nanocrystals has been demonstrated, with analysis revealing that the key step for its formation is probably the coupling between carbon dioxide or carboxyl with intermediates involved in the ethylene pathway. The conversion of carbon dioxide to value-added products using renewable electricity would potentially help to address current climate concerns. The electrochemical reduction of carbon dioxide to propylene, a critical feedstock, requires multiple C–C coupling steps with the transfer of 18 electrons per propylene molecule, and hence is kinetically sluggish. Here we present the electrosynthesis of propylene from carbon dioxide on copper nanocrystals with a peak geometric current density of −5.5 mA cm^−2. The metallic copper nanocrystals formed from CuCl precursor present preponderant Cu(100) and Cu(111) facets, likely to favour the adsorption of key *C_1 and *C_2 intermediates. Strikingly, the production rate of propylene drops substantially when carbon monoxide is used as the reactant. From the electrochemical reduction of isotope-labelled carbon dioxide mixed with carbon monoxide, we infer that the key step for propylene formation is probably the coupling between adsorbed/molecular carbon dioxide or carboxyl with the *C_2 intermediates that are involved in the ethylene pathway.