Benchmarking the Electrochemical CO₂ Reduction on Polycrystalline Copper Foils: The Importance of Microstructure Versus Applied Potential

Copper is one of the most promising catalysts for the CO₂ reduction reaction (CO₂RR) due to its unique capability of producing multicarbon products in appreciable quantities. Most of the CO₂RR research efforts have been directed towards the development of new electrocatalysts to either increase product selectivities or decrease overpotentials. In contrast, only a few studies have systematically tested or benchmarked CO₂RR performances of electrocatalysts. In this paper, for the first time, the performances of five different polycrystalline copper foils purchased from different suppliers are benchmarked for their CO₂RR performance. Their differences are characterized in terms of microstructural features and the effect that these microstructural properties have on the electrocatalytic behavior during potentiostatic CO₂RR experiments are evaluated. It is shown that the potential applied is the dominant factor controlling CO₂RR selectivities, leading to the conclusion that microstructural properties of polycrystalline copper electrodes have a negligible effect on the outcome of CO₂RR experiments.