Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The active sites of a working Fischer–Tropsch catalyst revealed by operando scanning tunnelling microscopy


Direct identification of the active sites of a working catalyst is still a major problem in heterogeneous catalysis. Here we present an operando scanning tunnelling microscopy study, in which insight into the nature of the active sites was obtained for the cobalt-catalysed Fischer–Tropsch synthesis. Experiments were performed on a Co(0001) sample under H2/CO gas mixtures at pressures of up to 950 mbar and a temperature of ~500 K. On the same apparatus, turnover frequencies were measured with a customized gas chromatograph. The density of monoatomic steps of the sample was varied by sputtering. The Fischer–Tropsch activity scaled with step density, from which steps are identified as the active sites of this reaction. The long-standing idea that the activation of the Co catalyst is connected with a roughening of the surface is not confirmed. The known activity function can be explained by pre-existing steps without roughening.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Catalytic activity of the Co(0001) sample measured in the STM cell.
Fig. 2: XPS spectra.
Fig. 3: STM images of the Co(0001) sample in UHV and in 950 mbar syngas.
Fig. 4: STM images of step fluctuations in syngas.
Fig. 5: STM images of the Co(0001) sample in syngas after sputtering.
Fig. 6: STM images of the smoothing of the sputtered Co(0001) sample in syngas.
Fig. 7: Plot of the CO-based TOFs versus step densities.

Data availability

The data that support the findings of this study are presented within the text and the supporting information or are available from the corresponding author upon reasonable request.


  1. 1.

    Taylor, H. S. & Armstrong, E. S. A theory of the catalytic surface. Proc. R. Soc. Lond. 108, 105–111 (1925).

    CAS  Google Scholar 

  2. 2.

    Boudart, M. Catalysis by Supported Metals. Adv. Catal. 20, 153–166 (1969).

    CAS  Google Scholar 

  3. 3.

    Zambelli, T., Wintterlin, J., Trost, J. & Ertl, G. Identification of the ‘active sites’ of a surface-catalyzed reaction. Science 273, 1688–1690 (1996).

    CAS  Google Scholar 

  4. 4.

    Davis, S. M., Zaera, F. & Somorjai, G. A. Surface structure and temperature dependence of light-alkane skeletal rearrangement reactions catalyzed over platinum single-crystal surfaces. J. Am. Chem. Soc. 104, 7453–7461 (1982).

    CAS  Google Scholar 

  5. 5.

    Hansen, P. L. et al. Atom-resolved imaging of dynamic shape changes in supported copper nanocrystals. Science 295, 2053–2055 (2002).

    CAS  PubMed  PubMed Central  Google Scholar 

  6. 6.

    Vendelbo, S. B. et al. Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation. Nat. Mater. 13, 884 (2014).

    CAS  PubMed  Google Scholar 

  7. 7.

    Wang, Z. J., Farra, R., Cao, J., Schlögl, R. & Willinger, M. G. The dynamics of active metal catalysts revealed by in situ electron microscopy. Microsc. Microanal. 22, 4–5 (2016).

    Google Scholar 

  8. 8.

    Jensen, J. A., Rider, K. B., Salmeron, M. & Somorjai, G. A. High pressure adsorbate structures studied by scanning tunneling microscopy: CO on Pt(111) in equilibrium with the gas phase. Phys. Rev. Lett. 80, 1228–1231 (1998).

    CAS  Google Scholar 

  9. 9.

    Österlund, L. et al. Bridging the pressure gap in surface science at the atomic level: H/Cu(110). Phys. Rev. Lett. 86, 460–463 (2001).

    PubMed  Google Scholar 

  10. 10.

    Hendriksen, B. L. M. & Frenken, J. W. M. CO oxidation on Pt(110): scanning tunneling microscopy inside a high-pressure flow reactor. Phys. Rev. Lett. 89, 046101 (2002).

    CAS  PubMed  Google Scholar 

  11. 11.

    Böcklein, S., Günther, S. & Wintterlin, J. High-pressure scanning tunneling microscopy of a silver surface during catalytic formation of ethylene oxide. Angew. Chem. Int. Ed. 52, 5518–5521 (2013).

    Google Scholar 

  12. 12.

    Pfisterer, J. H. K., Liang, Y., Schneider, O. & Bandarenka, A. S. Direct instrumental identification of catalytically active surface sites. Nature 549, 74–77 (2017).

    CAS  PubMed  Google Scholar 

  13. 13.

    Bartholomew, C. H. and Farrauto, R. J. Fundamentals of Industrial Catalytic Processes 2nd edn (Wiley-Interscience, 2006).

  14. 14.

    Kaiser, P., Pöhlmann, F. & Jess, A. Intrinsic and effective kinetics of cobalt-catalyzed fischer-tropsch synthesis in view of a power-to-liquid process based on renewable energy. Chem. Eng. Technol. 37, 964–972 (2014).

    CAS  Google Scholar 

  15. 15.

    den Breejen, J. P. et al. On the origin of the cobalt particle size effects in Fischer–Tropsch catalysis. J. Am. Chem. Soc. 131, 7197–7203 (2009).

    Google Scholar 

  16. 16.

    Oukaci, R., Singleton, A. H. & Goodwin, J. G. Comparison of patented Co F–T catalysts using fixed-bed and slurry bubble column reactors. Appl. Catal. A 186, 129–144 (1999).

    CAS  Google Scholar 

  17. 17.

    van Santen, R. A., Markvoort, A. J., Filot, I. A. W., Ghouri, M. M. & Hensen, E. J. M. Mechanism and microkinetics of the Fischer–Tropsch reaction. Phys. Chem. Chem. Phys. 15, 17038–17063 (2013).

    PubMed  Google Scholar 

  18. 18.

    Wilson, J. & de Groot, C. Atomic-scale restructuring in high-pressure catalysis. J. Phys. Chem. 99, 7860–7866 (1995).

    CAS  Google Scholar 

  19. 19.

    Geerlings, J. J. C., Zonnevylle, M. C. & de Groot, C. P. M. Studies of the Fischer–Tropsch reaction on Co(0001). Surf. Sci. 241, 302–314 (1991).

    CAS  Google Scholar 

  20. 20.

    Beitel, G. A., de Groot, C. P. M., Oosterbeek, H. & Wilson, J. H. A combined in-situ PM-RAIRS and kinetic study of single-crystal cobalt catalysts under synthesis gas at pressures up to 300 mbar. J. Phys. Chem. B 101, 4035–4043 (1997).

    CAS  Google Scholar 

  21. 21.

    Schulz, H. Selforganization in Fischer–Tropsch synthesis with iron- and cobalt catalysts. Catal. Today 228, 113–122 (2014).

    CAS  Google Scholar 

  22. 22.

    Banerjee, A. et al. Shape and size of cobalt nanoislands formed spontaneously on cobalt terraces during Fischer–Tropsch synthesis. J. Phys. Chem. Lett. 7, 1996–2001 (2016).

    CAS  PubMed  Google Scholar 

  23. 23.

    Zhang, X. Q., van Santen, R. A. & Hensen, E. J. M. Carbon-induced surface transformations of cobalt. ACS Catal. 5, 596–601 (2015).

    CAS  Google Scholar 

  24. 24.

    Ehrensperger, M. & Wintterlin, J. In situ high-pressure high-temperature scanning tunneling microscopy of a Co(0001) Fischer–Tropsch model catalyst. J. Catal. 319, 274–282 (2014).

    CAS  Google Scholar 

  25. 25.

    Ehrensperger, M. & Wintterlin, J. In situ scanning tunneling microscopy of the poisoning of a Co(0001) Fischer–Tropsch model catalyst by sulfur. J. Catal. 329, 49–56 (2015).

    CAS  Google Scholar 

  26. 26.

    Navarro, V., van Spronsen, M. A. & Frenken, J. W. M. In situ observation of self-assembled hydrocarbon Fischer–Tropsch products on a cobalt catalyst. Nat. Chem. 8, 929–934 (2016).

    CAS  PubMed  Google Scholar 

  27. 27.

    Rößler, M., Geng, P. & Wintterlin, J. A high-pressure scanning tunneling microscope for studying heterogeneous catalysis. Rev. Sci. Instrum. 76, 023705 (2005).

    Google Scholar 

  28. 28.

    Oosterbeek, H. Bridging the pressure and material gap in heterogeneous catalysis: cobalt fischer–tropsch catalysts from surface science to industrial application. Phys. Chem. Chem. Phys. 9, 3570–3576 (2007).

    CAS  PubMed  Google Scholar 

  29. 29.

    Yang, J. et al. Reaction mechanism of CO activation and methane formation on Co Fischer–Tropsch catalyst: a combined DFT, transient, and steady-state kinetic modeling. J. Catal. 308, 37–49 (2013).

    CAS  Google Scholar 

  30. 30.

    Huffman, G. P. et al. In-situ XAFS investigation of K-promoted Co catalysts. J. Catal. 151, 17–25 (1995).

    CAS  Google Scholar 

  31. 31.

    Ernst, B., Bensaddik, A., Hilaire, L., Chaumette, P. & Kiennemann, A. Study on a cobalt silica catalyst during reduction and Fischer–Tropsch reaction: in situ EXAFS compared to XPS and XRD. Catal. Today 39, 329–341 (1998).

    CAS  Google Scholar 

  32. 32.

    Cats, K. H. et al. X-ray nanoscopy of cobalt Fischer–Tropsch catalysts at work. Chem. Commun. 49, 4622–4624 (2013).

    CAS  Google Scholar 

  33. 33.

    Nishizawa, T. & Ishida, K. The Co (cobalt) system. Bull. Alloy Phase Diagr. 4, 387–390 (1983).

    Google Scholar 

  34. 34.

    Weststrate, C. J., van Helden, P., van de Loosdrecht, J. & Niemantsverdriet, J. W. Elementary steps in Fischer–Tropsch synthesis: CO bond scission, CO oxidation and surface carbiding on Co(0001). Surf. Sci. 648, 60–66 (2016).

    CAS  Google Scholar 

  35. 35.

    Böller, B., Ehrensperger, M. & Wintterlin, J. In situ scanning tunneling microscopy of the dissociation of CO on Co(0001). ACS Catal. 5, 6802–6806 (2015).

    Google Scholar 

  36. 36.

    Weststrate, C. J. et al. Atomic and polymeric carbon on Co(0001): surface reconstruction, graphene formation, and catalyst poisoning. J. Phys. Chem. C. 116, 11575–11583 (2012).

    CAS  Google Scholar 

  37. 37.

    Gong, X. Q., Raval, R. & Hu, P. CO dissociation and O removal on Co(0001): a density functional theory study. Surf. Sci. 562, 247–256 (2004).

    CAS  Google Scholar 

  38. 38.

    Qi, Y., Yang, J., Chen, D. & Holmen, A. Recent progresses in understanding of Co-based Fischer–Tropsch catalysis by means of transient kinetic studies and theoretical analysis. Catal. Lett. 145, 145–161 (2015).

    CAS  Google Scholar 

  39. 39.

    Hammer, B. & Nørskov, J. K. Theoretical surface science and catalysis—calculations and concepts. Adv. Catal. 45, 71–129 (2000).

    CAS  Google Scholar 

  40. 40.

    Van Santen, R. A. Complementary structure sensitive and insensitive catalytic relationships. Acc. Chem. Res. 42, 57–66 (2009).

    PubMed  Google Scholar 

  41. 41.

    Weststrate, C. J. et al. Interaction of hydrogen with flat (0001) and corrugated (11–20) and (10–12) cobalt surfaces: insights from experiment and theory. Catal. Today (2019).

  42. 42.

    Pestman, R., Chen, W. & Hensen, E. Insight into the rate-determining step and active sites in the Fischer–Tropsch reaction over cobalt catalysts. ACS Catal. 9, 4189–4195 (2019).

    CAS  Google Scholar 

  43. 43.

    van Helden, P., Ciobîcă, I. M. & Coetzer, R. L. J. The size-dependent site composition of FCC cobalt nanocrystals. Catal. Today 261, 48–59 (2016).

    Google Scholar 

  44. 44.

    Tsakoumis, N. E. et al. Fischer–Tropsch synthesis: an XAS/XRPD combined in situ study from catalyst activation to deactivation. J. Catal. 291, 138–148 (2012).

    CAS  Google Scholar 

  45. 45.

    Haddad, G. J., Chen, B. & Goodwin, J. J. G. Effect of La3+ promotion of Co/SiO2 on CO hydrogenation. J. Catal. 161, 274–281 (1996).

    CAS  Google Scholar 

  46. 46.

    Ribeiro, F. H., Schach Von Wittenau, A. E., Bartholomew, C. H. & Somorjai, G. A. Reproducibility of turnover rates in heterogeneous metal catalysis: compilation of data and guidelines for data analysis. Catal. Rev. 39, 49–76 (1997).

    CAS  Google Scholar 

  47. 47.

    Bezemer, G. L. et al. Cobalt particle size effects in the Fischer–Tropsch reaction studied with carbon nanofiber supported catalysts. J. Am. Chem. Soc. 128, 3956–3964 (2006).

    CAS  PubMed  Google Scholar 

  48. 48.

    Inderwildi, O. R., Jenkins, S. J. & King, D. A. Fischer–Tropsch mechanism revisited: alternative pathways for the production of higher hydrocarbons from synthesis gas. J. Phys. Chem. C. 1305–1307 (2008).

  49. 49.

    Yeh, J. J. & Lindau, I. Atomic subshell photoionization cross sections and asymmetry parameters: 1 Z 103. Data Nucl. Data Tables 32, 1–155 (1985).

    CAS  Google Scholar 

  50. 50.

    Reilman, R. F., Msezane, A. & Manson, S. T. Relative intensities in photoelectron spectroscopy of atoms and molecules. J. Electron. Spectrosc. Relat. Phenom. 8, 389–394 (1976).

    CAS  Google Scholar 

  51. 51.

    Tanuma, S., Powell, C. J. & Penn, D. R. Calculations of electron inelastic mean free paths. V. Data for 14 organic compounds over the 50–2000 eV range. Surf. Interface Anal. 21, 165–176 (1994).

    CAS  Google Scholar 

Download references


We gratefully acknowledge financial support by the German Science Foundation (DFG) through grant no. WI 1003/8–1. We thank S. Günther, TU Munich, for help with the preparation of Supplementary Fig. 3 and Supplementary Video 4.

Author information




B.B. performed the STM, XPS and GC measurements and analysed the data. K.M.D. deployed and tested the GC. B.B. and J.W. wrote the manuscript. J.W. conceived and supervised the project.

Corresponding author

Correspondence to Joost Wintterlin.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Supplementary Information

Supplementary Tables 1 and 2, Supplementary Figs. 1–4 and Supplementary References.

Supplementary Video 1

Time lapse of 18 STM images recorded during a period of 80 min on the same area of the sample. Conditions were a total pressure of 200 mbar syngas, an H2:CO = 2:1 mixture, and a sample temperature of 493 K. The first frame was taken 3.5 h after heating the sample to 493 K. Images 3 and 8 are displayed in Fig. 3(a) and (b) of the main text. The video was corrected for a small thermal drift. One can see that the step positions fluctuate, demonstrating the high mobility of cobalt atoms under the reaction conditions (200 × 200 nm2, Vt = −0.5 V, It = 0.7 nA).

Supplementary Video 2

Time lapse of 18 STM images recorded during a period of 25 min. The data were taken under 950 mbar syngas (H2:CO = 2:1) and at a sample temperature of 493 K. The first frame was taken 3 h after heating the sample to 493 K. The fringes of the steps are caused by cobalt atoms diffusing along the steps or exchanging between steps and terraces at a faster rate than the rate of the scan lines (7 Hz) (these effects are still slow compared to the 10−13 to 10−12 s time scale of elementary chemical processes, such as the dissociation of a CO molecule, which thus ‘see’ a static step) (18× 18 nm2, Vt = −0.5 V, It = 0.7 nA).

Supplementary Video 3

Time lapse of 19 STM images recorded during a period of 2.5 h. The data were recorded on the sputtered Co(0001) sample in 950 mbar syngas (H2:CO = 2:1) and at a sample temperature of 493 K. The first frame was taken 80 min after heating the sample to 493 K. The video shows that several of the topmost terraces shrink and at the same time that lower cobalt layers become partially or completely filled (90 × 90 nm2, Vt = 0.05 V, It = 0.7 nA).

Supplementary Video 4

Time lapse of the 19 STM images from Supplementary Video 3 showing the differences between successive images. Image no. 5 served as a reference image and was subtracted from all images to highlight the morphological changes (images no. 1 to no. 4 were not suitable as references because in this phase of the experiment the thermal drift was still too strong). By this subtraction, areas in images no. 6 to no. 19 where Co terraces grow by adding Co atoms to the steps appear bright, and areas where Co atoms are removed from the steps appear dark. Accordingly, image no. 5 itself appears homogeneously grey, and in images no. 1 to nos. 4 the bright/dark contrast of growing and shrinking terraces is inverted.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Böller, B., Durner, K.M. & Wintterlin, J. The active sites of a working Fischer–Tropsch catalyst revealed by operando scanning tunnelling microscopy. Nat Catal 2, 1027–1034 (2019).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing