The reduction of CO2 to C2 products like ethanol represents a promising alternative towards a carbon-neutral energy cycle. Although CO2 can be electrochemically reduced to small (C1, C2, and C3) organic compounds on copper electrodes, the selectivity and efficiency of the process is poor and the reaction mechanism is not well understood. Using density functional theory (DFT) simulations, we study a number of possible pathways for the reduction of CO2 to C2 products to deduce the most likely mechanism based on computed thermodynamic and kinetic data, as well as compatibility with reported experimental results. The proposed mechanism explains the formation of the seven C2 products observed experimentally (ethylene, ethanol, acetaldehyde, glycolaldehyde, glyoxal, ethylene glycol, and acetate). We identify key intermediates that determine selectivity, and the predicted product preferences and onset potentials are in good agreement with experiment. Our analysis also confirms various important experimental observations, including the importance of glyoxal as intermediate in the formation of ethanol and other oxygenated products.

On the mechanism of CO2 reduction to C2 products at copper surfaces

254th National Meeting (2017)

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