Electrochemical CO2 reduction on Cu2O-derived copper nanoparticles: controlling the catalytic selectivity of hydrocarbons.

The catalytic activity and hydrocarbon selectivity in electrochem. carbon dioxide (CO2) redn. on cuprous oxide (Cu2O) derived copper nanoparticles is discussed. Cuprous oxide films with [100], [110] and [111] orientation and variable thickness were electrodeposited by redn. of copper(II) lactate on com. available copper plates. After initiation of the electrochem. CO2 redn. by these oxide structures, the selectivity of the process largely depends on the parent Cu2O film thickness, rather than on the initial crystal orientation. Starting with thin Cu2O films, besides CO and hydrogen, selective formation of ethylene is obsd. with very high ethylene-to-methane ratios (∼8 to 12). In addn. to these products, thicker Cu2O films yield a remarkably large amt. of ethane. Long term faradaic efficiency anal. of hydrocarbons shows no sign of deactivation of the electrodes after 5 h of continuous expt. Online mass spectroscopy studies combined with x-ray diffraction data suggest the redn. of the Cu2O films in the presence of CO2, generating a nanoparticulate Cu morphol., prior to the prodn. of hydrogen, CO, and hydrocarbons. Optimizing coverage, no. d. and size of the copper nanoparticles, as well as local surface pH, may allow highly selective formation of the industrially important product ethylene. [on SciFinder(R)]