In interfacial charge-transfer reactions, the complexity of the reaction pathway increases with the number of charges transferred, and becomes even greater when the reaction involves both electrons (charge) and ions (mass). These so-called mixed ion and electron transfer (MIET) reactions are crucial in intercalation/insertion electrochemistry, such as that occurring in oxygen reduction/evolution electrocatalysts and lithium-ion battery electrodes. Understanding MIET reaction pathways, particularly identifying the rate-determining step (RDS), is crucial for engineering interfaces at the molecular, electronic and point defect levels. Here we develop a generalizable experimental and analysis framework for constructing the reaction pathway for the incorporation of O2(g) in Pr0.1Ce0.9O2−x. We converge on four candidates for the RDS (dissociation of neutral oxygen adsorbate) out of more than 100 possibilities by measuring the current density–overpotential curves while controlling both oxygen activity in the solid and oxygen gas partial pressure, and by quantifying the chemical and electrostatic driving forces using operando ambient pressure X-ray photoelectron spectroscopy.
Your institute does not have access to this article
Open Access articles citing this article.
Nature Communications Open Access 23 September 2020
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Source data that support the findings of this study are available from the corresponding author on request.
Bard, A. J. & Faulkner, L. R. Electrochemical Methods: Fundamentals and Applications 2nd edn (Wiley, 2000).
Li, Y. & Chueh, W. C. Electrochemical and chemical insertion for energy transformation and switching. Annu. Rev. Mater. Res. 48, 1–29 (2018).
Yao, H. C. & Yao, Y. F. Y. Ceria in automotive exhaust catalysts. I. Oxygen storage. J. Catal. 86, 254–265 (1984).
Graves, C., Ebbesen, S. D., Jensen, S. H., Simonsen, S. B. & Mogensen, M. B. Eliminating degradation in solid oxide electrochemical cells by reversible operation. Nat. Mater. 14, 239–244 (2015).
Irvine, J. T. S. et al. Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers. Nat. Energy 1, 15014 (2016).
Chueh, W. C. et al. High-flux solar-driven thermochemical dissociation of CO2 and H2O using nonstoichiometric ceria. Science 330, 1797–1801 (2010).
Shao, Z. et al. Investigation of the permeation behavior and stability of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ oxygen membrane. J. Memb. Sci. 172, 177–188 (2000).
Riva, M. et al. Influence of surface atomic structure demonstrated on oxygen incorporation mechanism at a model perovskite oxide. Nat. Commun. 9, 3710 (2018).
Merkle, R. & Maier, J. How is oxygen incorporated into oxides? A comprehensive kinetic study of a simple solid-state reaction with SrTiO3 as a model material. Angew. Chem. Int. Ed. Engl. 47, 3874–3894 (2008).
Adler, S. B. Factors governing oxygen reduction in solid oxide fuel cell cathodes. Chem. Rev. 104, 4791–4843 (2004).
Chueh, W. C., Hao, Y., Jung, W. & Haile, S. M. High electrochemical activity of the oxide phase in model ceria-Pt and ceria-Ni composite anodes. Nat. Mater. 11, 155–161 (2012).
Maier, J. On the correlation of macroscopic and microscopic rate constants in solid state chemistry. Solid State Ion. 112, 197–228 (1998).
Kilner, J. A., De Souza, R. A. & Fullarton, I. C. Surface exchange of oxygen in mixed conducting perovskite oxides. Solid State Ion. 86–88, 703–709 (1996).
Gopal, C. B. & Haile, S. M. An electrical conductivity relaxation study of oxygen transport in samarium doped ceria. J. Mater. Chem. A 2, 2405–2417 (2014).
Baumann, F. S. et al. Quantitative comparison of mixed conducting SOFC cathode materials by means of thin film model electrodes. J. Electrochem. Soc. 154, B931–B941 (2007).
Fleig, J., Merkle, R. & Maier, J. The p(O2) dependence of oxygen surface coverage and exchange current density of mixed conducting oxide electrodes: model considerations. Phys. Chem. Chem. Phys. 9, 2713–2723 (2007).
Merkle, R. & Maier, J. Oxygen incorporation into Fe-doped SrTiO3: mechanistic interpretation of the surface reaction. Phys. Chem. Chem. Phys. 4, 4140–4148 (2002).
De Souza, R. A. A universal empirical expression for the isotope surface exchange coefficients (k*) of acceptor-doped perovskite and fluorite oxides. Phys. Chem. Chem. Phys. 8, 890–897 (2006).
Jung, W. & Tuller, H. L. Investigation of surface Sr segregation in model thin film solid oxide fuel cell perovskite electrodes. Energy Environ. Sci. 5, 5370–5378 (2012).
Adler, S. B., Chen, X. Y. & Wilson, J. R. Mechanisms and rate laws for oxygen exchange on mixed-conducting oxide surfaces. J. Catal. 245, 91–109 (2007).
Cao, Y., Gadre, M. J., Ngo, A. T., Adler, S. B. & Morgan, D. D. Factors controlling surface oxygen exchange in oxides. Nat. Commun. 10, 1346 (2019).
Mastrikov, Y. A., Merkle, R., Heifets, E., Kotomin, E. A. & Maier, J. Pathways for oxygen incorporation in mixed conducting perovskites: a DFT-based mechanistic analysis for (La, Sr)MnO3-δ. J. Phys. Chem. C 114, 3017–3027 (2010).
Fleig, J. J. On the current–voltage characteristics of charge transfer reactions at mixed conducting electrodes on solid electrolytes. Phys. Chem. Chem. Phys. 7, 2027–2037 (2005).
Tuller, H. L. & Bishop, S. R. Point defects in oxides: tailoring materials through defect engineering. Annu. Rev. Mater. Res. 41, 369–398 (2011).
Guan, Z., Chen, D. & Chueh, W. C. Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes. Phys. Chem. Chem. Phys. 19, 23414–23424 (2017).
Schmid, A., Rupp, G. M. & Fleig, J. Voltage and partial pressure dependent defect chemistry in (La,Sr)FeO3-δ thin films investigated by chemical capacitance measurements. Phys. Chem. Chem. Phys. 20, 12016–12026 (2018).
Zurhelle, A. F., Tong, X., Klein, A., Mebane, D. S. & De Souza, R. A. A space-charge treatment of the increased concentration of reactive species at the surface of a ceria solid solution. Angew. Chem. Int. Ed. Engl. 56, 14516–14520 (2017).
De Souza, R. A. The formation of equilibrium space-charge zones at grain boundaries in the perovskite oxide SrTiO3. Phys. Chem. Chem. Phys. 11, 9939–9969 (2009).
De Souza, R. A. & Martin, M. Using 18O/16O exchange to probe an equilibrium space-charge layer at the surface of a crystalline oxide: method and application. Phys. Chem. Chem. Phys. 10, 2356–2367 (2008).
Chen, D., Bishop, S. R. & Tuller, H. L. Non-stoichiometry in oxide thin films: a chemical capacitance study of the praseodymium-cerium oxide system. Adv. Funct. Mater. 23, 2168–2174 (2013).
Chen, D., Bishop, S. R. S. & Tuller, H. L. Praseodymium-cerium oxide thin film cathodes: study of oxygen reduction reaction kinetics. J. Electroceram. 28, 62–69 (2012).
Seo, H. G., Choi, Y. & Jung, W. Exceptionally enhanced electrode activity of (Pr,Ce)O2-δ-based cathodes for thin-film solid oxide fuel cells. Adv. Energy Mater. 1703647, 1–7 (2018).
Bishop, S. R., Stefanik, T. S. & Tuller, H. L. Electrical conductivity and defect equilibria of Pr0.1Ce0.9O2-δ. Phys. Chem. Chem. Phys. 13, 10165–10173 (2011).
Jung, W. & Tuller, H. L. A new model describing solid oxide fuel cell cathode kinetics: model thin film SrTi1-xFexO3-δ mixed conducting oxides-a case study. Adv. Energy Mater 1, 1184 (2011).
Kuklja, M. M., Kotomin, Ea, Merkle, R., Mastrikov, Ya & Maier, J. Combined theoretical and experimental analysis of processes determining cathode performance in solid oxide fuel cells. Phys. Chem. Chem. Phys. 15, 5443–5471 (2013).
Chen, D. Characterization and Control of Non-stoichiometry in Pr 0.1Ce 0.9O 2-δ Thin Films: Correlation with SOFC Electrode Performance. PhD Thesis, Massachusetts Institute of Technology (2014).
Zhao, L., Perry, N. H., Daio, T., Sasaki, K. & Bishop, S. R. Improving the Si impurity tolerance of Pr0.1Ce0.9O2-δ SOFC electrodes with reactive surface additives. Chem. Mater. 27, 3065–3070 (2015).
Simons, P., Ji, H. Il, Davenport, T. C. & Haile, S. M. A piezomicrobalance system for high-temperature mass relaxation characterization of metal oxides: a case study of Pr-doped ceria. J. Am. Ceram. Soc. 100, 1161–1171 (2017).
Riess, I. Characterization of solid oxide fuel cells based on solid electrolytes or mixed ionic electronic conductors. Solid State Ion. 90, 91–104 (2003).
Adler, S. B. Reference electrode placement in thin solid electrolytes. J. Electrochem. Soc. 149, E166–E172 (2002).
Thole, B. T. et al. 3d X-ray-absorption lines and the 3d 94f n+1 multiplets of the lanthanides. Phys. Rev. B 32, 5107–5118 (1985).
Karnatak, R. et al. X-ray absorption studies of CeO2, PrO2, and TbO2. I. Manifestation of localized and extended f states in the 3d absorption spectra. Phys. Rev. B 36, 1745–1749 (1987).
Lu, Q. et al. Surface defect chemistry and electronic structure of Pr0.1Ce0.9O2-δ revealed in operando. Chem. Mater. 30, 2600–2606 (2018).
Chueh, W. C. & Haile, S. M. Electrochemistry of mixed oxygen ion and electron conducting electrodes in solid electrolyte cells. Annu. Rev. Chem. Biomol. Eng. 3, 313–341 (2012).
Feng, Z. A. et al. Origin of overpotential-dependent surface dipole at CeO2–x/gas interface during electrochemical oxygen insertion reactions. Chem. Mater. 28, 6233–6242 (2016).
Nenning, A. et al. Ambient pressure XPS study of mixed conducting perovskite-type SOFC cathode and anode materials under well-defined electrochemical polarization. J. Phys. Chem. C 120, 1461–1471 (2016).
Siegbahn, H. & Lundholm, M. A method of depressing gaseous-phase electron lines in liquid-phase ESCA spectra. J. Electron Spectrosc. Relat. Phenom. 28, 135–138 (1982).
Guan, Z. Probing and Tuning Far-from-Equilibrium Oxygen Exchange Kinetics on Electrochemical Solid-Gas Interfaces. PhD thesis, Stanford Univ. (2018).
Schaube, M., Merkle, R. & Maier, J. Oxygen exchange kinetics on systematically doped ceria: a pulsed isotope exchange study. J. Mater. Chem. A 7, 21854–21866 (2019).
Tsvetkov, N., Lu, Q., Sun, L., Crumlin, E. J. & Yildiz, B. Improved chemical and electrochemical stability of perovskite oxides with less reducible cations at the surface. Nat. Mater. 15, 1010–1016 (2016).
Feng, Za, El Gabaly, F., Ye, X., Shen, Z.-X. & Chueh, W. C. Fast vacancy-mediated oxygen ion incorporation across the ceria–gas electrochemical interface. Nat. Commun. 5, 4374 (2014).
Mueller, D. N., Machala, M. L., Bluhm, H. & Chueh, W. C. Redox activity of surface oxygen anions in oxygen-deficient perovskite oxides during electrochemical reactions. Nat. Commun. 6, 6097 (2015).
Frank Ogletree, D., Bluhm, H., Hebenstreit, E. D. & Salmeron, M. Photoelectron spectroscopy under ambient pressure and temperature conditions. Nucl. Instrum. Methods Phys. Res. A 601, 151–160 (2009).
Whaley, J. A. et al. Note: fixture for characterizing electrochemical devices in-operando in traditional vacuum systems. Rev. Sci. Instrum. 81, 086104 (2010).
This work was supported by the National Science Foundation under award no. 1336835. MIT researcher was supported by grant DE SC0002633 funded by the US Department of Energy, Office of Basic Science. The Advanced Light Source was supported by the Director, Office of Science, Office of Basic Energy Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences of the US Department of Energy at the Lawrence Berkeley National Laboratory under contract no. DE-AC02-05CH11231. We thank C.-C. Chen from Stanford University and Q. Lu from Oak Ridge National Laboratory for critical reading of the manuscript and helpful discussions on XAS. We thank Q. Xu and W. Zhong from Tsinghua University for helpful discussions on data visualization.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Chen, D., Guan, Z., Zhang, D. et al. Constructing a pathway for mixed ion and electron transfer reactions for O2 incorporation in Pr0.1Ce0.9O2−x. Nat Catal 3, 116–124 (2020). https://doi.org/10.1038/s41929-019-0401-9
Nature Reviews Materials (2021)
High mass-specific reactivity of a defect-enriched Ru electrocatalyst for hydrogen evolution in harsh alkaline and acidic media
Science China Materials (2021)
Nature Catalysis (2020)
Nature Communications (2020)
Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides
Nature Catalysis (2020)