Electrochemical Reduction of CO_2 using Supported Cu_2O Catalysts

摘要

We have studied the electrochemical reduction of CO_2 to produce short chain hydrocarbons and alcohols using supported Cu_2O electrocatalysts. The catalysts are prepared using Cu_2O nanoparticles formed by chemical reduction of aqueous CuCl_2 mixed with polyethylene glycol surfactant, followed by addition of NaOH and L-ascorbic acid (sodium). The nanoparticles are then added to a Nafion/ethanol solution and coated onto a carbon fiber support. When tested used for CO_2 electroreduction at -1.5 V(NHE), the Cu_2O particles are reduced to metallic Cu, but the hydrocarbon product distribution remains different from that reported for conventional metallic Cu electrodes. Ethylene is the major hydrocarbon produced, with a Faradaic efficiency around 25%, while the efficiency for CH4 formation is reduced to around 1%. The major alcohol product is ethanol, with a Faradaic efficiency around 6%. The relative formation rates of the individual products are discussed in terms of the relevant branch points in recent computational models for the overall reaction mechanism.