Abstract
The electrochemical CO2 reduction reaction on Cu is widely believed to occur via two consecutive and orthogonal reaction steps, that is, CO2-to-CO and CO-to-C2+, on the same sites. Here we provide compelling experimental evidence that challenges these long-held assumptions. We show that the presence of CO2 promotes the electrochemical CO reduction reaction, and there are at least two distinct types of Cu sites, with one (CuCO2) more active in the CO2-to-CO conversion and the other (CuCO) favouring the further reduction of CO to C2+ products. CO adsorbed on CuCO is at least six times more active towards the formation of C2+ products than that on CuCO2. Isotopic labelling experiments on Cu(111) and Cu(100) surfaces indicate that CuCO2 and CuCO probably correspond to Cu(111)-like and defect sites, respectively. These insights highlight the possibility of selectivity control in the CO2 reduction reaction.
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Acknowledgements
This work is supported by the Beijing National Laboratory for Molecular Sciences. W.G. acknowledges the support of the Project funded by China Postdoctoral Science Foundation (2022M710183). The authors thank Y. Zhang and C. Fan for the assistance with numerical analysis.
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W.G., Y.X. and B.X. conceived the idea and designed experiments in this study. W.G. synthesized and characterized the catalysts, and conducted the electrochemical tests. Y.X. performed SEIRAS experiments. L.F. performed part of the electrochemical tests. W.G., Y.X., X.C. and B.X. analysed data, and co-wrote the manuscript, with input from all other co-authors.
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Nature Catalysis thanks Joel Ager III, Wen-Bin Cai and the other, anonymous, reviewer for their contribution to the peer review of this work.
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Supplementary Figs. 1–31, Notes 1–6, Tables 1–4 and References 1–8.
Supplementary Data 1
Source data for supplementary figures.
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Source Data Fig. 1
Co-electrolysis of CO/CO2 and in situ spectroscopic characterization.
Source Data Fig. 2
Co-electrolysis of 13CO/12CO2 (4:1) on Den-Cu.
Source Data Fig. 3
Distribution of ethylene isotopologues in the co-electrolysis of 13CO/12CO2.
Source Data Fig. 4
Isotopologue distribution of C2 products in the co-electrolysis of 13CO/12CO2.
Source Data Fig. 5
The two-site model and its predictions.
Source Data Fig. 6
Distribution of ethylene isotopologues on single crystal Cu surface.
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Gao, W., Xu, Y., Fu, L. et al. Experimental evidence of distinct sites for CO2-to-CO and CO conversion on Cu in the electrochemical CO2 reduction reaction. Nat Catal 6, 885–894 (2023). https://doi.org/10.1038/s41929-023-01002-6
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DOI: https://doi.org/10.1038/s41929-023-01002-6
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