Cu(I) Reducibility Controls Ethylene vs Ethanol Selectivity on (100)-Textured Copper during Pulsed CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) can convert widely available CO2 into value-added C-2 products, such as ethylene and ethanol. However, low selectivity toward either compound limits the effectiveness of current CO2RR electrocatalysts. Here, we report the use of pulsed overpotentials to improve the ethylene selectivity to 67% with >75% overall C-2 selectivity on (100)-textured polycrystalline Cu foil. The pulsed CO2RR can be made selective to either ethylene or ethanol by controlling the reaction temperature. We attribute the enhanced C-2 selectivity to the improved CO dimerization kinetics on the active Cu surface on predominately (100)-textured Cu grains with the reduced hydrogen adsorption coverage during the pulsed CO2RR. The ethylene vs ethanol selectivity can be explained by the reducibility of the Cu(I) species during the cathodic potential cycle. Our work demonstrates a simple route to improve the ethylene vs ethanol selectivity and identifies Cu(I) as the species responsible for ethanol production.

Automated summary

The study demonstrates the enhancement of ethylene selectivity and achievement of selectivity towards either ethylene or ethanol by using pulsed overpotentials. The improved CO dimerization kinetics on active Cu surface and reduced hydrogen adsorption coverage during pulsed CO2RR are crucial for achieving this goal.