The electrochemical reduction of CO2 driven by renewable sources of electricity (wind and solar) offers a potentially attractive means for producing fuels and chemicals from CO2 taken from stationary sources and the atmosphere. The desired products of the CO2 reduction reaction (CO2RR) are ethene and ethanol, since these compounds can be readily converted to higher molecular weight compounds by conventional catalysis. Extensive research has shown that the only electrocatalyst capable of producing ethene and ethanol with high faradaic yield is metallic copper (Cu), The yield of these products is enhanced by using roughened surfaces of Cu, which exhibit a high proportion of low coordination sites that CO and C2 intermediates strongly. The selectivity to these products is further enhanced by the presence of a strong electrostatic field in the Helmholtz double layer present at the catalyst-electrolyte inionterface. We have shown that the intensity of this field increases when Cs+, rather than Li+ is used as the electrolyte cation. More recently, we have found that the product distribution can be further tuned towards ethene and ethanol by coating the Cu surface with a thin ionomer film, a solid electrolyte. Proper choice of ionomer properties enables tuning of the CO2 and H2O concentrations, the pH, and the concentration of electrolyte cations and anions near the Cu surface. This talk will discuss how these variables can be controlled in order achieve maximum product selectivity control for the CO2RR over Cu.

Effects of liquid and solid electrolytes on the activity and selectivity of Cu for the electrochemical reduction of CO2

ACS Spring Meeting 2021

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