Can the CO2 Reduction Reaction be Improved on Cu: Selectivity and Intrinsic Activity of Functionalized Cu Surfaces

18 October 2022, Version 6
This content is a preprint and has not undergone peer review at the time of posting.


Cu is currently the most effective monometallic catalyst for producing valuable multi-carbon-based products, such as ethylene and ethanol, from the CO2 reduction reaction (CO2RR). One approach to optimize the activity and selectivity of the metal Cu catalyst is to functionalize the Cu electrode with a molecular modifier. We investigate from a data standpoint whether any reported functionalized Cu catalyst improves the intrinsic activity and/or multi-carbon product selectivity compared to the performance of bare Cu foil and the best single crystal Cu facets. Our analysis shows that the reported increases in activity are due to increased surface roughness and disappear once normalizing with respect to electrochemical surface area. The intrinsic activity generally falls below that of bare Cu foil, both for total and product-specific current, which we attribute to non-selective blocking of active sites by the modifier on the surface. Instead, we show that the modifier allows for easier diffusion of CO2 compared to H2O to the surface, leading to greater selectivity for CO2RR and C2+ products. As such, our analysis finds no catalyst for CO2RR that intrinsically outperforms bare Cu.


CO2 reduction
Copper catalyst
Molecular modifiers
Surface roughness
Intrinsic activity

Supplementary materials

Supplementary Information
Supplementary information containing additional plots, along with tables of data.


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