Key role of chemistry versus bias in electrocatalytic oxygen evolution

Abstract

The oxygen evolution reaction has an important role in many alternative-energy schemes because it supplies the protons and electrons required for converting renewable electricity into chemical fuels1,2,3. Electrocatalysts accelerate the reaction by facilitating the required electron transfer4, as well as the formation and rupture of chemical bonds5. This involvement in fundamentally different processes results in complex electrochemical kinetics that can be challenging to understand and control, and that typically depends exponentially on overpotential1,2,6,7. Such behaviour emerges when the applied bias drives the reaction in line with the phenomenological Butler–Volmer theory, which focuses on electron transfer8, enabling the use of Tafel analysis to gain mechanistic insight under quasi-equilibrium9,10,11 or steady-state assumptions12. However, the charging of catalyst surfaces under bias also affects bond formation and rupture13,14,15, the effect of which on the electrocatalytic rate is not accounted for by the phenomenological Tafel analysis8 and is often unknown. Here we report pulse voltammetry and operando X-ray absorption spectroscopy measurements on iridium oxide to show that the applied bias does not act directly on the reaction coordinate, but affects the electrocatalytically generated current through charge accumulation in the catalyst. We find that the activation free energy decreases linearly with the amount of oxidative charge stored, and show that this relationship underlies electrocatalytic performance and can be evaluated using measurement and computation. We anticipate that these findings and our methodology will help to better understand other electrocatalytic materials and design systems with improved performance.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Measured electrocatalytic response of IrOx/Ti-250 °C.
Fig. 2: Charge storage under steady-state and potentiodynamic conditions.
Fig. 3: Computed surface pH–potential phase diagram.
Fig. 4: Computed mechanism and energetics of water–oxyl coupling.
Fig. 5: Computed electrocatalytic response of IrO2.

Data availability

All data are available in the main text or the supplementary materials and from the Open Research Data Repository of the Max Planck Society, https://doi.org/10.17617/3.48Source data are provided with this paper.

References

  1. 1.

    Gür, T. M. Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage. Energy Environ. Sci. 11, 2696–2767 (2018); correction 11, 3055–3055 (2018).

    Article  Google Scholar 

  2. 2.

    Seh, Z. W. et al. Combining theory and experiment in electrocatalysis: insights into materials design. Science 355, eaad4998 (2017).

    Article  Google Scholar 

  3. 3.

    Hu, C., Zhang, L. & Gong, J. Recent progress made in the mechanism comprehension and design of electrocatalysts for alkaline water splitting. Energy Environ. Sci. 12, 2620–2645 (2019).

    CAS  Article  Google Scholar 

  4. 4.

    Marcus, R. A. Electron transfer reactions in chemistry. Theory and experiment. Rev. Mod. Phys. 65, 599–610 (1993).

    CAS  Article  Google Scholar 

  5. 5.

    Marcus, R. A. Theoretical relations among rate constants, barriers, and Brønsted slopes of chemical reactions. J. Phys. Chem. 72, 891–899 (1968).

    CAS  Article  Google Scholar 

  6. 6.

    Seitz, L. C. et al. A highly active and stable IrOx/SrIrO3 catalyst for the oxygen evolution reaction. Science 353, 1011–1014 (2016).

    ADS  CAS  Article  Google Scholar 

  7. 7.

    Nong, H. N. et al. A unique oxygen ligand environment facilitates water oxidation in hole-doped IrNiOx core–shell electrocatalysts. Nat. Catal. 1, 841–851 (2018).

    CAS  Article  Google Scholar 

  8. 8.

    Schmickler, W. & Santos, E. Interfacial Electrochemistry (Springer, 2010).

  9. 9.

    Shinagawa, T., Garcia-Esparza, A. T. & Takanabe, K. Insight on Tafel slopes from a microkinetic analysis of aqueous electrocatalysis for energy conversion. Sci. Rep. 5, 13801 (2015); correction 10, 6899 (2020).

    ADS  Article  Google Scholar 

  10. 10.

    De Faria, L. A., Boodts, J. F. C. & Trasatti, S. Electrocatalytic properties of ternary oxide mixtures of composition Ru0.3Ti(0.7−x)CexO2: oxygen evolution from acidic solution. J. Appl. Electrochem. 26, 1195–1199 (1996).

    Article  Google Scholar 

  11. 11.

    Lyons, M. E. G. & Brandon, M. P. A comparative study of the oxygen evolution reaction on oxidised nickel, cobalt and iron electrodes in base. J. Electroanal. Chem. (Lausanne) 641, 119–130 (2010).

    CAS  Article  Google Scholar 

  12. 12.

    Mefford, J. T., Zhao, Z., Bajdich, M. & Chueh, W. C. Interpreting Tafel behavior of consecutive electrochemical reactions through combined thermodynamic and steady state microkinetic approaches. Energy Environ. Sci. 13, 622–634 (2020).

    CAS  Article  Google Scholar 

  13. 13.

    Corrigan, D. A. The catalysis of the oxygen evolution reaction by iron impurities in thin film nickel oxide electrodes. J. Electrochem. Soc. 134, 377 (1987).

    ADS  CAS  Article  Google Scholar 

  14. 14.

    Pearce, P. E. et al. Revealing the reactivity of the iridium trioxide intermediate for the oxygen evolution reaction in acidic media. Chem. Mater. 31, 5845–5855 (2019).

    CAS  Article  Google Scholar 

  15. 15.

    Grimaud, A. et al. Activation of surface oxygen sites on an iridium-based model catalyst for the oxygen evolution reaction. Nat. Energy 2, 16189 (2017); erratum 2, 17002 (2017).

    ADS  CAS  Article  Google Scholar 

  16. 16.

    Augustyn, V., Simon, P. & Dunn, B. Pseudocapacitive oxide materials for high-rate electrochemical energy storage. Energy Environ. Sci. 7, 1597–1614 (2014).

    CAS  Article  Google Scholar 

  17. 17.

    Conway, B. E. in Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications (ed. Conway, B. E.) 221–257 (Springer, 1999).

  18. 18.

    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  Article  Google Scholar 

  19. 19.

    Clancy, J. P. et al. Spin–orbit coupling in iridium-based 5d compounds probed by X-ray absorption spectroscopy. Phys. Rev. B 86, 195131 (2012).

    ADS  Article  Google Scholar 

  20. 20.

    Pfeifer, V. et al. In situ observation of reactive oxygen species forming on oxygen-evolving iridium surfaces. Chem. Sci. 8, 2143–2149 (2017).

    CAS  Article  Google Scholar 

  21. 21.

    Frevel, L. J. et al. In situ X-ray spectroscopy of the electrochemical development of iridium nanoparticles in confined electrolyte. J. Phys. Chem. C 123, 9146–9152 (2019).

    CAS  Article  Google Scholar 

  22. 22.

    Bard, A. J. & Faulkner, L. R. Electrochemical Methods – Fundamentals and Applications (John Wiley & Sons, 2000).

  23. 23.

    Gauthier, J. A., Dickens, C. F., Chen, L. D., Doyle, A. D. & Nørskov, J. K. Solvation effects for oxygen evolution reaction catalysis on IrO2(110). J. Phys. Chem. C 121, 11455–11463 (2017).

    CAS  Article  Google Scholar 

  24. 24.

    Otani, M. & Sugino, O. First-principles calculations of charged surfaces and interfaces: a plane-wave nonrepeated slab approach. Phys. Rev. B 73, 115407 (2006).

    ADS  Article  Google Scholar 

  25. 25.

    Bonnet, N., Morishita, T., Sugino, O. & Otani, M. First-principles molecular dynamics at a constant electrode potential. Phys. Rev. Lett. 109, 266101 (2012).

    ADS  Article  Google Scholar 

  26. 26.

    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  Article  Google Scholar 

  27. 27.

    Rossmeisl, J., Qu, Z.-W., Zhu, H., Kroes, G.-J. & Nørskov, J. K. Electrolysis of water on oxide surfaces. J. Electroanal. Chem. 607, 83–89 (2007).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We thank HZB for synchrotron radiation beamtime and the High-Performance Computing Center Stuttgart (HLRS) for access to the HazelHen and Hawk supercomputers as part of the ECHO project. Part of this work was carried out at Petra III (beamline P64) and we thank V. Murzin, A. Tayal and W. Caliebe for assistance and acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for access. We thank M. Hashagen, J. Allan and F. Girgsdies for BET and X-ray diffraction measurements and A. Müller-Kauke for inductively coupled plasma–optical emission spectrometry measurements. Financial support from the German Research Foundation (DFG) under Priority Program 1613 and Grant STR 596/11-1 is acknowledged. P.S. acknowledges partial funding by the DFG under Germany’s Excellence Strategy – EXC 2008/1 – 390540038 (zum Teil gefördert durch die Deutsche Forschungsgemeinschaft (DFG) im Rahmen der Exzellenzstrategie des Bundes und der Länder – EXC 2008/1 – 390540038).

Author information

Affiliations

Authors

Contributions

T.E.J. and D.T. designed the study, analysed data and wrote the manuscript. H.N.N. carried out electrochemical measurements with the help of M.K., H.P.T. and C.S.; H.N.N., L.J.F., C.S. and D.T. performed soft-X-ray measurements. H.N.N., A.B., J.T. and D.T. performed hard-X-ray measurements. T.E.J. performed DFT calculations with the help of S.P.; G.Z. prepared Cl-treated samples under the supervision of J.P.-R.; H.N.N. prepared the IrOx-250 ºC, IrOx-450 ºC and IrNi samples. J.P.-R., B.R.C., R.S. and P.S. offered guidance for the project. All authors commented on the manuscript.

Corresponding authors

Correspondence to Detre Teschner or Travis E. Jones.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature thanks Shannon Boettcher and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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

Supplementary information

Supplementary Information

The SI pdf contains Supplementary Methods, Supplementary Discussion, Supplementary Figures 1 to 22, Supplementary Tables 1 to 7, and references. The text and display items present an extended discussion on methodology of the employed techniques, additional characterization, and results from additional materials, including Cl treatment.

Video 1

ca. 5 ps water dynamics on surface with 0/4 ML θh+.

Video 2

ca. 5 ps water dynamics on surface with 1/4 ML θh+.

Video 3

ca. 5 ps water dynamics on surface with 1/2 ML θh+.

Video 4

ca. 5 ps water dynamics on surface with 3/4 ML θh+.

Video 5

ca. 5 ps water dynamics on surface with 4/4 ML θh+.

Source data

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Nong, H.N., Falling, L.J., Bergmann, A. et al. Key role of chemistry versus bias in electrocatalytic oxygen evolution. Nature 587, 408–413 (2020). https://doi.org/10.1038/s41586-020-2908-2

Download citation

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

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