Selective formation of C2 products from the electrochemical conversion of CO2 on CuO-derived copper electrodes comprised of nanoporous ribbon arrays

Abstract

Promotion of CC bond coupling in the electrochemical conversion of CO2 to fuels is of great scientific and practical interest. Selective formation of C2 over the C1 products, however, is a formidable challenge on all electrocatalysts known in literature. Here, we report the selectivity of CuO-derived porous copper nanoribbon arrays as the electrode to convert CO2 to C2 products. The CC bond coupling occurred at electrode potentials <−0.701V vs. RHE. The total Faradaic efficiency towards the formation of these C2 compounds (C2H4, C2H6 and C2H5OH) reached to ∼40% at −0.816V vs. RHE under ambient pressure and temperature. More importantly, at the same condition, the total Faradaic efficiency for C1 products (CO and HCOO−) was <3%, which were major products when a Cu2O-derived Cu electrode was used. Methane was not observed, a key product on a Cu foil electrode. This increased selectivity towards the formation of C2 chemicals, meanwhile suppressed C1 chemicals, are attributed to the presence of surface defects and a large number of grain boundaries on the CuO-derived porous Cu nanoribbon arrays electrode. Moreover, the activation of CO2 was found to likely occur at the copper surface; while the presence of copper oxide layer reported in literature may result from the interaction between copper and water during the post analysis process.