Electrochemical Reduction of CO2 using Supported Cu2O Nanoparticles

We have studied the electrochemical reduction of CO2 using Cu2O catalysts prepared by nanoparticle synthesis (i.e., chemical reduction) and by electrochemical deposition. Both preparation methods give catalysts that exhibit high formation rates for CO and C2H4 relative to CH4, compared to Cu foil electrodes. The main difference is a higher relative rate of CO formation using the nanoparticle catalysts. Highly loaded nanoparticle catalysts give the highest overall rates for CO2 product formation, most likely because of their greater surface area. Lower loaded catalysts show evidence that product selectivity is affected by the competing H-2 reaction on the carbon fiber support. Characterization using SEM and XRD together with transient current behavior suggests that Cu2O is reduced in two stages, with the initial formation of dispersed Cu clusters occurring rapidly on the oxide surface, followed by a much slower reduction of the interior of the oxide.