Self-activation of copper electrodes during CO electro-oxidation in alkaline electrolyte


The development of low-temperature fuel cells for clean energy production is an appealing alternative to fossil-fuel technologies. CO is a key intermediate in the electro-oxidation of energy carrying fuels and, due to its strong interaction with state-of-the-art Pt electrodes, it is known to act as a poison. Here we demonstrate the ability of Earth-abundant Cu to electro-oxidize CO efficiently in alkaline media, reaching high current densities of ≥0.35 mA cm−2 on single-crystal Cu(111) model catalysts. Strong and continuous surface structural changes are observed under reaction conditions. Supported by first-principles microkinetic modelling, we show that the concomitant presence of high-energy undercoordinated Cu structures at the surface is a prerequisite for the high activity. Similar CO-induced self-activation has been reported for gas–surface reactions at coinage metals, demonstrating the strong parallels between heterogeneous thermal catalysis and heterogeneous electrocatalysis.

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Fig. 1: CO electro-oxidation on Cu(111) with an onset prior to copper bulk oxidation.
Fig. 2: In situ EC-IRRAS during CO electro-oxidation on Cu(111) model catalysts.
Fig. 3: First-principles microkinetic modelling of the catalytic activity.
Fig. 4: Direct EC-STM visualization of Cu(111) under CO oxidation reaction conditions.
Fig. 5: Schematic representation of the self-activation of Cu(111) during CO electro-oxidation.

Data availability

All the data supporting the findings of this study are available within the paper and its Supplementary Information files. The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Code availability

The scripts used for the modified microkinetic simulations using the open source CatMAP code are given separately from the Supplementary Information in the following GitHub repository:


  1. 1.

    Gilman, S. The mechanism of electrochemical oxidation of carbon monoxide and methanol on platinum. J. Phys. Chem. 68, 70–80 (1964).

    CAS  Google Scholar 

  2. 2.

    Markovic, N. M. & Ross, P. N. Surface science studies of model fuel cell electrocatalysts. Surf. Sci. Rep. 45, 117–229 (2002).

    CAS  Google Scholar 

  3. 3.

    Korzeniewski, C., Climent, V. & Feliu, J. M. in Electroanalytical Chemistry: A Series of Advances Vol. 24 (eds Bard, A. J. & Zoski, C.) 75–169 (CRC Press, 2011).

  4. 4.

    Koper, M. T. M., Lai, S. C. S. & Herrero, E. in Fuel Cell Catalysis: A Surface Science Approach (ed. Koper, M. T. M.) 159–207 (Wiley, 2008).

  5. 5.

    García, G. & Koper, M. T. M. Carbon monoxide oxidation on Pt single crystal electrodes: Understanding the catalysis for low temperature fuel cells. ChemPhysChem 12, 2064–2072 (2011).

    PubMed  Google Scholar 

  6. 6.

    Edens, G. J., Hamelin, A. & Weaver, M. J. Mechanism of carbon monoxide electrooxidation on monocrystalline gold surfaces: Identification of a hydroxycarbonyl intermediate. J. Phys. Chem. 100, 2322–2329 (1996).

    CAS  Google Scholar 

  7. 7.

    Blizanac, B. B., Arenz, M., Ross, P. N. & Markovic, N. M. Surface electrochemistry of CO on reconstructed gold single crystal surfaces studied by infrared reflection absorption spectroscopy and rotating disk electrode. J. Am. Chem. Soc. 126, 10130–10141 (2004).

    CAS  PubMed  Google Scholar 

  8. 8.

    Rodríguez, P., Koverga, A. A. & Koper, M. T. M. Carbon monoxide as a promoter for its own oxidation on a gold electrode. Angew. Chem. 122, 1263–1265 (2010).

    Google Scholar 

  9. 9.

    Rodríguez, P., García-Araez, N. & Koper, M. T. M. Self-promotion mechanism for CO electrooxidation on gold. Phys. Chem. Chem. Phys. 12, 9373–9380 (2010).

    PubMed  Google Scholar 

  10. 10.

    Iwasita, T. & Ciapina, E. G. in Handbook of Fuel Cells Vol 5,6 (eds Vielstich, W. et al.) 1–16 (Wiley, 2010).

  11. 11.

    Roberts, J. L. & Sawyer, D. T. Electrochemical oxidation of carbon monoxide at gold electrodes. Electrochim. Acta 10, 989–1000 (1965).

    CAS  Google Scholar 

  12. 12.

    Kita, H., Nakajima, H. & Hayashi, K. Electrochemical oxidation of CO on Au in alkaline solution. J. Electroanal. Chem. 190, 141–156 (1985).

    CAS  Google Scholar 

  13. 13.

    Sun, S. G., Cai, W., Bin, Wan, L. J. & Osawa, M. Infrared absorption enhancement for CO adsorbed on Au films in perchloric acid solutions and effects of surface structure studied by cyclic voltammetry, scanning tunneling microscopy, and surface-enhanced IR spectroscopy. J. Phys. Chem. B 103, 2460–2466 (1999).

    CAS  Google Scholar 

  14. 14.

    Chang, S.-C., Hamelin, A. & Weaver, M. J. Dependence of the electrooxidation rates of carbon monoxide at gold on the surface crystallographic orientation: a combined kinetic-surface infrared spectroscopic study. J. Phys. Chem. 95, 5560–5567 (1991).

    CAS  Google Scholar 

  15. 15.

    Rodríguez, P., Feliu, J. M. & Koper, M. T. M. Unusual adsorption state of carbon monoxide on single-crystalline gold electrodes in alkaline media. Electrochem. Commun. 11, 1105–1108 (2009).

    Google Scholar 

  16. 16.

    Rodríguez, P., García-Araez, N., Koverga, A., Frank, S. & Koper, M. T. M. CO electroxidation on gold in alkaline media: A combined electrochemical, spectroscopic, and DFT Study. Langmuir 26, 12425–12432 (2010).

    PubMed  Google Scholar 

  17. 17.

    Eren, B., Heine, C., Bluhm, H., Somorjai, G. A. & Salmeron, M. Catalyst chemical state during CO oxidation reaction on Cu(111) studied with ambient-pressure X-ray photoelectron spectroscopy and near edge X-ray adsorption fine structure spectroscopy. J. Am. Chem. Soc. 137, 11186–11190 (2015).

    CAS  PubMed  Google Scholar 

  18. 18.

    Xu, F. et al. Redox-mediated reconstruction of copper during carbon monoxide oxidation. J. Phys. Chem. C. 118, 15902–15909 (2014).

    CAS  Google Scholar 

  19. 19.

    Konnik, E. I. Electrochemical oxidation of carbon monoxide in aqueous solutions. Russ. Chem. Rev. 42, 111–119 (1973).

    Google Scholar 

  20. 20.

    Newton, M. A. Dynamic adsorbate/reaction induced structural change of supported metal nanoparticles: heterogeneous catalysis and beyond. Chem. Soc. Rev. 37, 2644–2657 (2008).

    CAS  PubMed  Google Scholar 

  21. 21.

    Schlögl, R. Heterogeneous catalysis. Angew. Chem. Int. Ed. 54, 3465–3520 (2015).

    Google Scholar 

  22. 22.

    Reuter, K. Ab initio thermodynamics and first-principles microkinetics for surface catalysis. Catal. Lett. 146, 541–563 (2016).

    CAS  Google Scholar 

  23. 23.

    Eren, B. et al. Activation of Cu(111) surface by decomposition into nanoclusters driven by CO adsorption. Science 351, 475–478 (2016).

    CAS  PubMed  Google Scholar 

  24. 24.

    Kodama, K., Morimoto, Y., Strmcnik, D. S. & Markovic, N. M. The role of non-covalent interactions on CO bulk oxidation on Pt single crystal electrodes in alkaline electrolytes. Electrochim. Acta 152, 38–43 (2015).

    CAS  Google Scholar 

  25. 25.

    Kunze-Liebhäuser, J. in Encyclopedia of Interfacial Chemistry. Surface Science and Electrochemistry Vol. 5 (ed. Wandelt, K.) 107–120 (Elsevier, 2018).

  26. 26.

    Strehblow, H.-H. & Titze, B. The investigation of the passive behaviour of copper in weakly acid and alkaline solutions and the examination of the passive film by ESCA and ISS. Electrochim. Acta 25, 839–850 (1980).

    CAS  Google Scholar 

  27. 27.

    Kautek, W. & Gordon, J. G. II XPS studies of anodic surface films on copper electrodes. J. Electrochem. Soc. 137, 2672–2677 (1990).

    CAS  Google Scholar 

  28. 28.

    Scott, S. B. et al. Absence of oxidized phases in Cu under CO reduction conditions. ACS Energy Lett. 4, 803–804 (2019).

    CAS  Google Scholar 

  29. 29.

    Maurice, V., Strehblow, H.-H. & Marcus, P. In situ STM study of the initial stages of oxidation of Cu(111) in aqueous solution. Surf. Sci. 458, 185–194 (2000).

    CAS  Google Scholar 

  30. 30.

    Salimon, J., Hernández-Romero, R. M. & Kalaji, M. The dynamics of the conversion of linear to bridge bonded CO on Cu. J. Electroanal. Chem. 538–539, 99–108 (2002).

    Google Scholar 

  31. 31.

    Shaw, S. K. et al. Role of axially coordinated surface sites for electrochemically controlled carbon monoxide adsorption on single crystal copper electrodes. Phys. Chem. Chem. Phys. 13, 5242–5251 (2011).

    CAS  PubMed  Google Scholar 

  32. 32.

    Hori, Y., Koga, O., Watanabe, Y. & Matsuo, T. FTIR measurements of charge displacement adsorption of CO on poly- and single crystal (100) of Cu electrodes. Electrochim. Acta 44, 1389–1395 (1998).

    CAS  Google Scholar 

  33. 33.

    Arihara, K., Kitamura, F., Ohsaka, T. & Tokuda, K. Characterization of the adsorption state of carbonate ions at the Au(111) electrode surface using in situ IRAS. J. Electroanal. Chem. 510, 128–135 (2001).

    CAS  Google Scholar 

  34. 34.

    Zamlynny, V. & Lipkowski, J. in Advances in Electrochemical Science and Engineering Vol. 9 (eds. Alkire, R. C. et al.) 315–376 (Wiley-VCH Verlag GmbH & Co. KGaA, 2006).

  35. 35.

    Baz, A. & Holewinski, A. Understanding the interplay of bifunctional and electronic effects: Microkinetic modeling of the CO electro-oxidation reaction. J. Catal. 384, 1–13 (2020).

    CAS  Google Scholar 

  36. 36.

    Kunze, J., Maurice, V., Klein, L. H., Strehblow, H.-H. & Marcus, P. In situ STM study of the effect of chlorides on the initial stages of anodic oxidation of Cu(111) in alkaline solutions. Electrochim. Acta 48, 1157–1167 (2003).

    CAS  Google Scholar 

  37. 37.

    Wang, J. et al. Formation, migration, and reactivity of Au–CO Complexes on Gold Surfaces. J. Am. Chem. Soc. 138, 1518–1526 (2016).

    CAS  PubMed  Google Scholar 

  38. 38.

    Citrin, P. H. & Wertheim, G. K. Photoemission from surface-atom core levels, surface densities of states, and metal-atom clusters: A unified picture. Phys. Rev. B 27, 3176–3200 (1983).

    CAS  Google Scholar 

  39. 39.

    Blyholder, G. Molecular orbital view of chemisorbed carbon monoxide. J. Phys. Chem. 68, 2772–2778 (1964).

    CAS  Google Scholar 

  40. 40.

    Andersen, M., Medford, A. J., Nørskov, J. K. & Reuter, K. Analyzing the case for bifunctional catalysis. Ang. Chem. Int. Ed. 55, 5210 (2016).

    CAS  Google Scholar 

  41. 41.

    Andersen, M., Medford, A. J., Nørskov, J. K. & Reuter, K. Scaling-relation-based analysis of bifunctional catalysis: The case for homogeneous bimetallic alloys. ACS Catal. 7, 3960 (2017).

    CAS  Google Scholar 

  42. 42.

    Necas, D. & Klapetek, P. Gwyddion: an open-source software for SPM data analysis. Cent. Eur. J. Phys. 10, 181–188 (2012).

    Google Scholar 

  43. 43.

    Auer, A. & Kunze-Liebhäuser, J. A universal quasi-reference electrode for in situ EC-STM. Electrochem. Commun. 98, 15–18 (2019).

    CAS  Google Scholar 

  44. 44.

    Tiwari, A., Maagaard, T., Chorkendorff, I. & Horch, S. Effect of dissolved glassware on the structure-sensitive part of the Cu(111) voltammogram in KOH. ACS Energy Lett. 4, 1645–1649 (2019).

    CAS  Google Scholar 

  45. 45.

    Medford, A. J. et al. CatMAP: A software package for descriptor-based microkinetic mapping of catalytic trends. Catal. Lett. 145, 794–807 (2015).

    CAS  Google Scholar 

  46. 46.

    Giannozzi, P. et al. QUANTUM ESPRESSO: A modular and open-source software project for quantum simulations of materials. J. Phys. Condens. Matter 21, 395502 (2009).

    PubMed  PubMed Central  Google Scholar 

  47. 47.

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    CAS  Google Scholar 

  48. 48.

    Garrity, K. F., Bennett, J. W., Rabe, K. M. & Vanderbilt, D. Pseudopotentials for high-throughput DFT calculations. Comput. Mater. Sci. 81, 446–452 (2014).

    CAS  Google Scholar 

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A.A. is a recipient of a doctorate (DOC) Fellowship of the Austrian Academy of Sciences at the Institute of Physical Chemistry. E.-M.W. and J.K.-L. acknowledge funding by the Austrian Science Foundation (FWF) through grant I-4114. N.G.H. and K.R. acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy – EXC 2089/1 – 390776260. Additionally, we thank B. Kindler for assistance with preparation of the Cu single crystals.

Author information




J.K.-L and K.R. supervised and coordinated the project. A.A and E.-M.W. designed and conducted the experiments. A.A. carried out the cyclic voltammetry and in situ EC-STM experiments. E.-M.W. conducted the in situ EC-IRRAS measurements. A.A. and N.B. did the RDE measurements. N.G.H. performed the DFT calculations and M.A. performed the microkinetic modelling. A.A., M.A., E.-M.W., K.R. and J. K.-L. contributed to the manuscript writing. All authors discussed and revised the manuscript.

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Correspondence to Julia Kunze-Liebhäuser.

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Extended data

Extended Data Fig. 1 Current transients show high electrocatalytic reversibility.

Potential steps to -0.63VSHE (black) and -0.45VSHE (grey), showing the high reversibility of CO oxidation on Cu(111). The reference potential was set to -0.85VSHE. Insets: current densities versus step number.

Extended Data Fig. 2 Control EC-STM studies in CO-free electrolyte.

EC-STM at -0.45 VSHE in Ar-saturated 0.1 M NaOH, where the surface is imaged over a long period of time (> 1.5 hours). In comparison to the structural changes during the CO bulk oxidation at the exact same potential, the images in the CO-free 0.1 M NaOH indicate unidirectional Cu transport upon Cu(111) reconstruction. Although a high degree of step edge roughening due to OH adsorption-induced reconstruction can be observed, there is only little formation of nanoscale Cu adatom islands. A much higher stability of the surface morphology after reconstruction is observed. No additional growth of adatom islands and nanostructures is seen upon scanning of up to an hour, which means there is no apparent surface diffusion. a, 100 x 100 nm2 (Itip = 1 nA) and bd, 50 x 50 nm2 (Itip = 4 nA). Etip = -0.5 VSHE.

Extended Data Fig. 3 Electronic structure analysis of OH and CO on Cu adatoms at Cu(111).

Atom and momentum projected PDOS of a, OH and b, CO adsorbed on top of a Cu adatom (labelled as Cuad) located in the fcc site of Cu(111). All results are from SCCS implicit solvation calculations, which allow an absolute alignment of the energy scale with the vacuum level and the simulation of appropriate molecular reference states, namely CO(aq) and charged OH-(aq). The Fermi level (EF) and d-band centres are indicated by dashed and dotted lines. c, The charge-density difference plot for OH-(aq) adsorption indicates partially remaining negative charge on the Cuad–OH complex. The shown isosurface corresponds to 0.0135e3 (red) and -0.0135e3 (blue), the purple region indicates the implicit solvation cavity. d, The changes in the 3d PDOS of adsorbed Cuad and of surface Cu(111) show the significant difference of CO adsorption as compared to OH.

Supplementary information

Supplementary Information

Supplementary Figs. 1–11, Table 1, Notes 1–10, input files, and references 1–25.

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Auer, A., Andersen, M., Wernig, E. et al. Self-activation of copper electrodes during CO electro-oxidation in alkaline electrolyte. Nat Catal 3, 797–803 (2020).

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