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.

Operando identification of site-dependent water oxidation activity on ruthenium dioxide single-crystal surfaces


Understanding the nature of active sites is central to controlling (electro)catalytic activity. Here we employed surface X-ray scattering coupled with density functional theory and surface-enhanced infrared absorption spectroscopy to examine the oxygen evolution reaction on RuO2 surfaces as a function of voltage. At 1.5 VRHE, our results suggest that there is an –OO group on the coordinatively unsaturated ruthenium (RuCUS) site of the (100) surface (and similarly for (110)), but adsorbed oxygen on the RuCUS site of (101). Density functional theory results indicate that the removal of –OO from the RuCUS site, which is stabilized by a hydrogen bond to a neighbouring –OH (–OO–H), could be the rate-determining step for (100) (similarly for (110)), where its reduced binding on (100) increased activity. A further reduction in binding energy on the RuCUS site of (101) resulted in a different rate-determining step (–O + H2O – (H+ + e) → –OO–H) and decreased activity. Our study provides molecular details on the active sites, and the influence of their local coordination environment on activity.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: The coordination and electronic structure of surface ruthenium and oxygen atoms on different facets of RuO2.
Fig. 2: A DFT-calculated reaction free energy diagram at 1.5 VDFT-RHE.
Fig. 3: Potential-dependent surface structures for RuO2(100).
Fig. 4: Potential-dependent surface structures for RuO2(101).
Fig. 5: Surface-dependent water oxidation kinetics on RuO2.
Fig. 6: The reaction mechanism and water oxidation activity on polycrystalline RuO2 surfaces.

Data availability

The data supporting the findings of this study are available in the paper and its Supplementary Information. Extra data are available from the corresponding authors on reasonable request.


  1. 1.

    Gray, H. B. Powering the planet with solar fuel. Nat. Chem. 1, 7 (2009).

    CAS  PubMed  Article  Google Scholar 

  2. 2.

    Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature 570, 504–508 (2019).

    CAS  PubMed  Article  Google Scholar 

  3. 3.

    Liu, C., Colón, B. C., Ziesack, M., Silver, P. A. & Nocera, D. G. Water splitting–biosynthetic system with CO2 reduction efficiencies exceeding photosynthesis. Science 352, 1210–1213 (2016).

    CAS  PubMed  Article  Google Scholar 

  4. 4.

    Zhang, J., Zhao, Z., Xia, Z. & Dai, L. A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol. 10, 444–452 (2015).

    CAS  PubMed  Article  Google Scholar 

  5. 5.

    Lee, Y., Suntivich, J., May, K. J., Perry, E. E. & Shao-Horn, Y. Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions. J. Phys. Chem. Lett. 3, 399–404 (2012).

    CAS  PubMed  Article  Google Scholar 

  6. 6.

    Over, H. Surface chemistry of ruthenium dioxide in heterogeneous catalysis and electrocatalysis: from fundamental to applied research. Chem. Rev. 112, 3356–3426 (2012).

    CAS  PubMed  Article  Google Scholar 

  7. 7.

    Chu, Y. S., Lister, T. E., Cullen, W. G., You, H. & Nagy, Z. Commensurate water monolayer at the RuO2(110)/water interface. Phys. Rev. Lett. 86, 3364–3367 (2001).

    CAS  PubMed  Article  Google Scholar 

  8. 8.

    Calle-Vallejo, F. et al. Finding optimal surface sites on heterogeneous catalysts by counting nearest neighbors. Science 350, 185–189 (2015).

    CAS  PubMed  Article  Google Scholar 

  9. 9.

    Nørskov, K. J. et al. The nature of the active site in heterogeneous metal catalysis. Chem. Soc. Rev. 37, 2163–2171 (2008).

    PubMed  Article  CAS  Google Scholar 

  10. 10.

    Sun, Q., Reuter, K. & Scheffler, M. Effect of a humid environment on the surface structure of RuO2(110). Phys. Rev. B 67, 205424 (2003).

    Article  CAS  Google Scholar 

  11. 11.

    Abbott, D. F. et al. Oxygen reduction on nanocrystalline ruthenia—local structure effects. RSC Adv. 5, 1235–1243 (2014).

    Article  CAS  Google Scholar 

  12. 12.

    Over, H. et al. Atomic-scale structure and catalytic reactivity of the RuO2(110). Surf. Sci. 287, 1474–1476 (2000).

    CAS  Google Scholar 

  13. 13.

    Over, H. et al. Visualization of atomic processes on ruthenium dioxide using scanning tunneling microscopy. ChemPhysChem 5, 167–174 (2004).

    CAS  PubMed  Article  Google Scholar 

  14. 14.

    Madhavaram, H. et al. Oxidation reactions over RuO2: a comparative study of the reactivity of the (110) single crystal and polycrystalline surfaces. J. Catal. 202, 296–307 (2001).

    CAS  Article  Google Scholar 

  15. 15.

    Exner, K. S., Anton, J., Jacob, T. & Over, H. Full kinetics from first principles of the chlorine evolution reaction over a RuO2(110) model electrode. Angew. Chem. Int. Ed. 55, 7501–7504 (2016).

    CAS  Article  Google Scholar 

  16. 16.

    Wang, Y., Jacobi, K., Schöne, W.-D. & Ertl, G. Catalytic oxidation of ammonia on RuO2(110) surfaces: mechanism and selectivity. J. Phys. Chem. B 109, 7883–7893 (2005).

    CAS  PubMed  Article  Google Scholar 

  17. 17.

    Wang, Y., Jacobi, K. & Ertl, G. Interaction of NO with the stoichiometric RuO2(110) surface. J. Phys. Chem. B 107, 13918–13924 (2003).

    CAS  Article  Google Scholar 

  18. 18.

    Rao, R. R. et al. Towards identifying the active sites on RuO2(110) in catalyzing oxygen evolution. Energy Environ. Sci. 10, 2626–2637 (2017).

    CAS  Article  Google Scholar 

  19. 19.

    Roy, C. et al. Trends in activity and dissolution on RuO2 under oxygen evolution conditions: particles versus well-defined extended surfaces. ACS Energy Lett. 3, 2045–2051 (2018).

    CAS  Article  Google Scholar 

  20. 20.

    Mu, R. et al. Deprotonated water dimers: the building blocks of segmented water chains on rutile RuO2(110). J. Phys. Chem. C 119, 23552–23558 (2015).

    CAS  Article  Google Scholar 

  21. 21.

    Mu, R. et al. Dimerization induced deprotonation of water on RuO2(110). J. Phys. Chem. Lett. 5, 3445–3450 (2014).

    CAS  PubMed  Article  Google Scholar 

  22. 22.

    Rao, R. R. et al. Surface orientation dependent water dissociation on rutile ruthenium dioxide. J. Phys. Chem. C 122, 17802–17811 (2018).

    CAS  Article  Google Scholar 

  23. 23.

    Stoerzinger, K. A., Qiao, L., Biegalski, M. D. & Shao-Horn, Y. Orientation-dependent oxygen evolution activities of rutile IrO2 and RuO2. J. Phys. Chem. Lett. 5, 1636–1641 (2014).

    CAS  PubMed  Article  Google Scholar 

  24. 24.

    Hepel, T., Pollak, F. H. & O’Grady, W. E. Effect of crystallographic orientation of single-crystal RuO2 electrodes on the hydrogen adsorption reactions. J. Electrochem. Soc. 131, 2094–2100 (1984).

    CAS  Article  Google Scholar 

  25. 25.

    Kuo, D.-Y. et al. Influence of surface adsorption on the oxygen evolution reaction on IrO2(110). J. Am. Chem. Soc. 139, 3473–3479 (2017).

    CAS  PubMed  Article  Google Scholar 

  26. 26.

    Kuo, D.-Y. et al. Measurements of oxygen electroadsorption energies and oxygen evolution reaction on RuO2(110): a discussion of the sabatier principle and its role in electrocatalysis. J. Am. Chem. Soc. 140, 17597–17605 (2018).

    CAS  PubMed  Article  Google Scholar 

  27. 27.

    Stoerzinger, K. A. et al. The role of Ru redox in pH-dependent oxygen evolution on rutile ruthenium dioxide. Surf. Chem. 2, 668–675 (2017).

    CAS  Google Scholar 

  28. 28.

    Stoerzinger, K. A. et al. Orientation-dependent oxygen evolution on RuO2 without lattice exchange. ACS Energy Lett. 2, 876–881 (2017).

    CAS  Article  Google Scholar 

  29. 29.

    Lee, Y.-L., Kleis, J., Rossmeisl, J., Shao-Horn, Y. & Morgan, D. Prediction of solid oxide fuel cell cathode activity with first-principles descriptors. Energy Environ. Sci. 4, 3966–3970 (2011).

    CAS  Article  Google Scholar 

  30. 30.

    Grimaud, A. et al. Activating lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution. Nat. Chem. 9, 457–465 (2017).

    CAS  PubMed  Article  Google Scholar 

  31. 31.

    Kim, Y. D., Schwegmann, S., Seitsonen, A. P. & Over, H. Epitaxial growth of RuO2(100) on Ru(101̄0): surface structure and other properties. J. Phys. Chem. B 105, 2205–2211 (2001).

    CAS  Article  Google Scholar 

  32. 32.

    Dickens, C. F., Montoya, J. H., Kulkarni, A. R., Bajdich, M. & Nørskov, J. K. An electronic structure descriptor for oxygen reactivity at metal and metal-oxide surfaces. Surf. Sci. 681, 122–129 (2019).

    CAS  Article  Google Scholar 

  33. 33.

    Dickens, C. F., Kirk, C. & Nørskov, J. K. Insights into the electrochemical oxygen evolution reaction with ab initio calculations and microkinetic modeling: beyond the limiting potential volcano. J. Phys. Chem. C 123, 18960–18977 (2019).

    CAS  Article  Google Scholar 

  34. 34.

    Vojvodic, A. et al. On the behavior of Brønsted–Evans–Polanyi relations for transition metal oxides. J. Chem. Phys. 134, 244509 (2011).

    CAS  PubMed  Article  Google Scholar 

  35. 35.

    Geiger, S. et al. The stability number as a metric for electrocatalyst stability benchmarking. Nat. Catal. 1, 508–515 (2018).

    CAS  Article  Google Scholar 

  36. 36.

    Ping, Y., Nielsen, R. J. & Goddard, W. A. The reaction mechanism with free energy barriers at constant potentials for the oxygen evolution reaction at the IrO2 (110) surface. J. Am. Chem. Soc. 139, 149–155 (2017).

    CAS  PubMed  Article  Google Scholar 

  37. 37.

    Pedersen, A. F. et al. Operando XAS study of the surface oxidation state on a monolayer IrOx on RuOx and Ru oxide based nanoparticles for oxygen evolution in acidic media. J. Phys. Chem. B 122, 878–887 (2018).

    PubMed  Article  CAS  Google Scholar 

  38. 38.

    Jensen, K. D. et al. Elucidation of the oxygen reduction volcano in alkaline media using a copper–platinum(111) alloy. Angew. Chem. Int. Ed. 57, 2800–2805 (2018).

    CAS  Article  Google Scholar 

  39. 39.

    Rizo, R., Herrero, E. & Feliu, M. J. Oxygen reduction reaction on stepped platinum surfaces in alkaline media. Phys. Chem. Chem. Phys. 15, 15416–15425 (2013).

    CAS  PubMed  Article  Google Scholar 

  40. 40.

    Böckris, J., Reddy, A. & Gamboa-Aldeco, M. Modern Electrochemistry, 2A: Fundamentals of Electrodics (Springer, 2000).

  41. 41.

    Bockris, J. O. Kinetics of activation controlled consecutive electrochemical reactions: anodic evolution of oxygen. J. Chem. Phys. 24, 817–827 (1956).

    CAS  Article  Google Scholar 

  42. 42.

    Castelli, P., Trasatti, S., Pollak, F. H. & O’Grady, W. E. Single crystals as model electrocatalysts: oxygen evolution on RuO2 (110). J. Electroanal. Chem. Interfacial Electrochem. 210, 189–194 (1986).

    CAS  Article  Google Scholar 

  43. 43.

    Bard, A. J., Faulkner, L. R., Leddy, J. & Zoski, C. G. Electrochemical Methods: Fundamentals and Applications Vol. 2 (Wiley, 1980).

  44. 44.

    Guiton, T. A. & Pantano, C. G. Infrared reflectance spectroscopy of porous silicas. Colloids Surf. Physicochem. Eng. Asp. 74, 33–46 (1993).

    CAS  Article  Google Scholar 

  45. 45.

    Huang, Y.-F., Kooyman, P. J. & Koper, M. T. M. Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy. Nat. Commun. 7, 12440 (2016).

    CAS  PubMed  PubMed Central  Article  Google Scholar 

  46. 46.

    Frydendal, R. et al. Benchmarking the stability of oxygen evolution reaction catalysts: the importance of monitoring mass losses. ChemElectroChem 1, 2075–2081 (2014).

    CAS  Article  Google Scholar 

  47. 47.

    Paoli, E. A. et al. Oxygen evolution on well-characterized mass-selected Ru and RuO2 nanoparticles. Chem. Sci. 6, 190–196 (2014).

    PubMed  PubMed Central  Article  CAS  Google Scholar 

  48. 48.

    Wang, T., Jelic, J., Rosenthal, D. & Reuter, K. Exploring pretreatment–morphology relationships: ab initio Wulff construction for RuO2 nanoparticles under oxidising conditions. ChemCatChem 5, 3398–3403 (2013).

    CAS  Article  Google Scholar 

  49. 49.

    Wang, T. & Reuter, K. Structure sensitivity in oxide catalysis: first-principles kinetic Monte Carlo simulations for CO oxidation at RuO2(111). J. Chem. Phys. 143, 204702 (2015).

    PubMed  Article  CAS  Google Scholar 

  50. 50.

    Dickens, C. F. & Nørskov, J. K. A theoretical investigation into the role of surface defects for oxygen evolution on RuO2. J. Phys. Chem. C 121, 18516–18524 (2017).

    CAS  Article  Google Scholar 

  51. 51.

    Halck, N. B., Petrykin, V., Krtil, P. & Rossmeisl, J. Beyond the volcano limitations in electrocatalysis—oxygen evolution reaction. Phys. Chem. Chem. Phys. 16, 13682–13688 (2014).

    CAS  PubMed  Article  Google Scholar 

  52. 52.

    Chen, D., Fang, Y.-H. & Liu, Z.-P. Searching for active binary rutile oxide catalyst for water splitting from first principles. Phys. Chem. Chem. Phys. 14, 16612–16617 (2012).

    CAS  PubMed  Article  Google Scholar 

  53. 53.

    Lin, Y. et al. Chromium–ruthenium oxide solid solution electrocatalyst for highly efficient oxygen evolution reaction in acidic media. Nat. Commun. 10, 162 (2019).

    PubMed  PubMed Central  Article  CAS  Google Scholar 

  54. 54.

    Kadakia, K., Datta, M. K., Jampani, P. H., Park, S. K. & Kumta, P. N. Novel F-doped IrO2 oxygen evolution electrocatalyst for PEM based water electrolysis. J. Power Sources 222, 313–317 (2013).

    CAS  Article  Google Scholar 

  55. 55.

    Duan, L. et al. A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II. Nat. Chem. 4, 418–423 (2012).

    CAS  PubMed  Article  Google Scholar 

  56. 56.

    Lister, T. E. et al. Cathodic activation of RuO2 single crystal surfaces for hydrogen-evolution reaction. J. Electroanal. Chem. 554–555, 71–76 (2003).

    Article  CAS  Google Scholar 

  57. 57.

    Lister, T. E. et al. Electrochemical and X-ray scattering study of well defined RuO2 single crystal surfaces. J. Electroanal. Chem. 524–525, 201–218 (2002).

    Article  Google Scholar 

  58. 58.

    Gründer, Y. & Lucas, C. A. Surface X-ray diffraction studies of single crystal electrocatalysts. Nano Energy 29, 378–393 (2016).

    Article  CAS  Google Scholar 

  59. 59.

    Björck, M. & Andersson, G. GenX: an extensible X-ray reflectivity refinement program utilizing differential evolution. J. Appl. Crystallogr. 40, 1174–1178 (2007).

    Article  CAS  Google Scholar 

  60. 60.

    Petach, T. A. et al. Voltage-controlled interfacial layering in an ionic liquid on SrTiO3. ACS Nano 10, 4565–4569 (2016).

    CAS  PubMed  Article  Google Scholar 

  61. 61.

    Miki, A., Ye, S. & Osawa, M. Surface-enhanced IR absorption on platinum nanoparticles: an application to real-time monitoring of electrocatalytic reactions. Chem. Commun. 1500–1501 (2002)..

  62. 62.

    Osawa, M., Yoshii, K., Ataka, K. & Yotsuyanagi, T. Real-time monitoring of electrochemical dynamics by submillisecond time-resolved surface-enhanced infrared attenuated-total-reflection spectroscopy. Langmuir 10, 640–642 (1994).

    CAS  Article  Google Scholar 

  63. 63.

    Chen, Y. X., Miki, A., Ye, S., Sakai, H. & Osawa, M. Formate, an active intermediate for direct oxidation of methanol on Pt electrode. J. Am. Chem. Soc. 125, 3680–3681 (2003).

    CAS  PubMed  Article  Google Scholar 

  64. 64.

    Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558–561 (1993).

    CAS  Article  Google Scholar 

  65. 65.

    Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).

    CAS  Article  Google Scholar 

  66. 66.

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

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  67. 67.

    Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).

    Article  Google Scholar 

  68. 68.

    Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

    CAS  Article  Google Scholar 

  69. 69.

    Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188–5192 (1976).

    Article  Google Scholar 

  70. 70.

    M. W. Chase et al. NIST-JANAF Thermochemical Tables v.1.0 (National Institute of Standards and Technology, 1985);

  71. 71.

    Nørskov, J. K. et al. Origin of the overpotential for oxygen reduction at a fuel-cell cathode. J. Phys. Chem. B 108, 17886–17892 (2004).

    Article  CAS  Google Scholar 

Download references


This work was supported in part by the Toyota Research Institute through the Accelerated Materials Design and Discovery programme. We thank B. Han for transmission electron microscopy characterization of RuO2 nanoparticles and J. Corchado-Garcia for help during the CTR data collection. This work was supported in part by the Skoltech-MIT Center for Electrochemical Energy and the Cooperative Agreement between the Masdar Institute, UAE and the Massachusetts Institute of Technology, USA (grant no. 02/MI/MIT/CP/11/07633/GEN/G/00). The work by H.Y. was supported by US Department of Energy (DOE), Basic Energy Sciences (BES), Materials Sciences and Engineering Division, and the work by H.Z. and the use of the Advanced Photon Source were supported by DOE, BES, Scientific User Facility Division (SUFD) under contract no. DE-AC02-06CH11357. The work by A.M. was supported by DOE, BES, SUFD under contract no. DE-AC02-76SF00515. A.F.P. acknowledges the Danish Ministry for Higher Education and Science for an EliteForsk travel grant and the Strategic Research’s project NACORR (grant no. 12-133817). This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant no. ACI-154856283. This research also used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. T.V. and N.B.H acknowledge support through V-Sustain: the VILLUM Centre for the Science of Sustainable Fuels and Chemicals (grant no. 9455) from VILLUM FONDEN. I.E.L.S acknowledges the Peabody Visiting Associate Professorship, awarded by the Department of Mechanical Engineering at Massachusetts Institute of Technology.

Author information




Y.S.H. and R.R.R. conceived and designed the experiments. R.R.R. performed the electrochemical measurements. R.R.R., A.F.P., J.H., A.M., H.Y. and H.Z. participated in the surface diffraction measurements. M.J.K., L.G., J.R.L., N.B.H. and T.V. performed the DFT calculations and analysis. Y.K., J.H. and R.R.R. performed the in situ surface-enhanced FT–IR spectroscopy measurements. I.E.L.S. and I.C. participated in the discussion and interpretation of experimental and theoretical data. Y.S.H. and R.R.R. wrote the manuscript. All of the authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Reshma R. Rao or Yang Shao-Horn.

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

Supplemental Information

Supplementary Notes 1–9, Figs. 1–35 and Tables 1–24.

Supplementary Data 1

Surface structures from DFT calculations

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Rao, R.R., Kolb, M.J., Giordano, L. et al. Operando identification of site-dependent water oxidation activity on ruthenium dioxide single-crystal surfaces. Nat Catal 3, 516–525 (2020).

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