Dynamic charge and oxidation state of Pt/CeO2 single-atom catalysts

Abstract

The catalytic activity of metals supported on oxides depends on their charge and oxidation state. Yet, the determination of the degree of charge transfer at the interface remains elusive. Here, by combining density functional theory and first-principles molecular dynamics on Pt single atoms deposited on the CeO2 (100) surface, we show that the common representation of a static metal charge is oversimplified. Instead, we identify several well-defined charge states that are dynamically interconnected and thus coexist. The origin of this new class of strong metal–support interactions is the relative position of the Ce(4f) levels with respect to those of the noble metal, allowing electron injection to (or recovery from) the support. This process is phonon-assisted, as the Ce(4f) levels adjust by surface atom displacement, and appears for other metals (Ni) and supports (TiO2). Our dynamic model explains the unique reactivity found for activated single Pt atoms on ceria able to perform CO oxidation, meeting the Department of Energy 150 °C challenge for emissions.

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Fig. 1: Static PBE + U Pt adsorption energies on CeO2 (100).
Fig. 2: BOMD simulations of the Pt–nO systems.
Fig. 3: DOS decomposition for the Pt–2O systems with different oxidation states.
Fig. 4: CO oxidation on Pt–nO structures.

Data availability

The datasets generated during the current study are available in the ioChem-BD database55 (https://doi.org/10.19061/iochem-bd-1-78).

References

  1. 1.

    Stair, P. C. Metal-oxide interfaces: where the action is. Nat. Chem. 3, 345–346 (2011).

  2. 2.

    Lykhach, Y. et al. Counting electrons on supported nanoparticles. Nat. Mater. 15, 284–288 (2015).

  3. 3.

    Schneider, W.-D., Heyde, M. & Freund, H.-J. Charge control in model catalysis: the decisive role of the oxide–nanoparticle interface. Chemistry 24, 2317–2327 (2018).

  4. 4.

    Kumar, G. et al. Evaluating differences in the active-site electronics of supported Au nanoparticle catalysts using hammett and DFT studies. Nat. Chem. 10, 268–274 (2018).

  5. 5.

    Campbell, C. T. Catalyst–support interactions: electronic perturbations. Nat. Chem. 4, 597–598 (2012).

  6. 6.

    Tauster, S. J., Fung, S. C. & Garten, R. L. Strong metal–support interactions. Group 8 noble metals supported on titanium dioxide. J. Am. Chem. Soc. 100, 170–175 (1978).

  7. 7.

    Rodríguez, J. A. et al. Activity of CeOx and TiOx nanoparticles grown on Au(111) in the water–gas shift reaction. Science 318, 1757–1760 (2007).

  8. 8.

    Divins, N. J., Angurell, I., Escudero, C., Perez-Dieste, V. & Llorca, J. Influence of the support on surface rearrangements of bimetallic nanoparticles in real catalysts. Science 346, 620–623 (2014).

  9. 9.

    Fu, Q., Saltsburg, H. & Flytzani-Stephanopoulos, M. Active nonmetallic Au and Pt species on ceria-based water–gas shift catalysts. Science 301, 935–938 (2003).

  10. 10.

    Qiao, B. et al. Single-atom catalysis of CO oxidation using Pt1/FeOx. Nat. Chem. 3, 634–641 (2011).

  11. 11.

    Cargnello, M. et al. Control of metal nanocrystal size reveals metal–support interface role for ceria catalysts. Science 341, 771–773 (2013).

  12. 12.

    Therrien, A. J. et al. An atomic-scale view of single-site Pt catalysis for low-temperature CO oxidation. Nat. Catal. 1, 192–198 (2018).

  13. 13.

    Nagai, Y. et al. In situ redispersion of platinum autoexhaust catalysts: an on-line approach to increasing catalyst lifetimes? Angew. Chem. Int. Ed. 47, 9303–9306 (2008).

  14. 14.

    Gänzler, A. M. et al. Tuning the structure of platinum particles on ceria in situ for enhancing the catalytic performance of exhaust gas catalysts. Angew. Chem. Int. Ed. 56, 13078–13082 (2017).

  15. 15.

    Nie, L. et al. Activation of surface lattice oxygen in single-atom Pt/CeO2 for low-temperature CO oxidation. Science 358, 1419–1423 (2017).

  16. 16.

    Lin, J. et al. Remarkable performance of Ir1/FeOx single-atom catalyst in water gas shift reaction. J. Am. Chem. Soc. 135, 15314–15317 (2013).

  17. 17.

    Liu, P. et al. Photochemical route for synthesizing atomically dispersed palladium catalysts. Science 352, 797–800 (2016).

  18. 18.

    Wei, H. et al. FeOx-supported platinum single-atom and pseudo-single-atom catalysts for chemoselective hydrogenation of functionalized nitroarenes. Nat. Commun. 5, 5634 (2014).

  19. 19.

    McCabe, R. W. & Trovarelli, A. Forty years of catalysis by ceria: a success story. Appl. Catal. B Environ. 197, 1 (2016).

  20. 20.

    Trovarelli, A. & Llorca, J. Ceria catalysts at nanoscale: how do crystal shapes shape catalysis? ACS Catal. 7, 4716–4735 (2017).

  21. 21.

    Jones, J. et al. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science 353, 150–154 (2016).

  22. 22.

    Kunwar, D. et al. Stabilizing high metal loadings of thermally stable platinum single atoms on an industrial catalyst support. ACS Catal. 9, 3978–3990 (2019).

  23. 23.

    Zhou, G., Li, P., Ma, Q., Tian, Z. & Liu, Y. Density functional theory plus Hubbard U study of the segregation of Pt to the CeO2−x grain boundary. Nano Lett. 18, 1668–1677 (2018).

  24. 24.

    Dvoǐák, F. et al. Creating single-atom Pt-ceria catalysts by surface step decoration. Nat. Commun. 7, 10801–10808 (2016).

  25. 25.

    Bruix, A. et al. Maximum noble-metal efficiency in catalytic materials: atomically dispersed surface platinum. Angew. Chem. Int. Ed. 53, 10525–10530 (2014).

  26. 26.

    Zammit, M. et al. Future Sutomotive Aftertreatment Solutions: the 150°C Challenge Workshop Report Technical Report (Pacific Northwest National Laboratory, 2013).

  27. 27.

    Farmer, J. A. & Campbell, C. T. Ceria maintains smaller metal catalyst particles by strong metal-support bonding. Science 329, 933–936 (2010).

  28. 28.

    Wu, T. et al. Investigation of the redispersion of Pt nanoparticles on polyhedral ceria nanoparticles. J. Phys. Chem. Lett. 5, 2479–2483 (2014).

  29. 29.

    Pereira Hernandez, X. I. et al. Tuning Pt–CeO2 interactions by high-temperature vapor-phase synthesis for improved reducibility of lattice oxygen. Nat. Commun. 10, 1358 (2019).

  30. 30.

    Neitzel, A. et al. Atomically dispersed Pd, Ni, and Pt species in ceria-based catalysts: principal differences in stability and reactivity. J. Phys. Chem. C 120, 9852–9862 (2016).

  31. 31.

    Plata, J., Márquez, A. M. & Sanz, J. F. Electron mobility via polaron hopping in bulk ceria: a first-principles study. J. Phys. Chem. C 117, 14502–14509 (2013).

  32. 32.

    Reticcioli, M. et al. Polaron-driven surface reconstructions. Phys. Rev. X 7, 031053 (2017).

  33. 33.

    Capdevila-Cortada, M. & López, N. Entropic contributions enhance polarity compensation for CeO2 (100) surfaces. Nat. Mater. 16, 328–334 (2017).

  34. 34.

    Walsh, A., Sokol, A. A., Buckeridge, J., Scanlon, D. O. & Catlow, C. R. A. Oxidation states and ionicity. Nat. Mater. 17, 958–964 (2018).

  35. 35.

    Lykhach, Y. et al. Reactivity of atomically dispersed Pt2+ species towards H2: model Pt–CeO2 fuel cell catalyst. Phys. Chem. Chem. Phys. 18, 7672–7679 (2016).

  36. 36.

    Greenwood, N. N. & Earnshaw, A. Chemistry of the Elements. 2nd edn, (Elsevier: 1997).

  37. 37.

    Ouyang, R., Liu, J.-X. & Li, W.-X. Atomistic theory of Ostwald ripening and disintegration of supported metal particles under reaction conditions. J. Am. Chem. Soc. 135, 1760–1771 (2013).

  38. 38.

    Datye, A. K. & Wang, Y. Atom trapping: a novel approach to generate thermally stable and regenerable single-atom catalysts. Natl Sci. Rev. 5, 630–632 (2018).

  39. 39.

    Kramida, A., Ralchenko, Y., Reader, J. & Team, N. A. Atomic Spectra Database (version 5.5.6) (National Institute of Standards and Technology, 2018); https://physics.nist.gov/cgi-bin/ASD/ie.pl

  40. 40.

    Capdevila-Cortada, M., García-Melchor, M. & López, N. Unraveling the structure sensitivity in methanol conversion on CeO2: a DFT + U study. J. Catal. 327, 58–64 (2015).

  41. 41.

    Andersin, J., Nevalaita, J., Honkala, K. & Häkkinen, H. The redox chemistry of gold with high-valence doped calcium oxide. Angew. Chem. Int. Ed. 52, 1424–1427 (2013).

  42. 42.

    Kowalski, P. M., Camellone, M. F., Nair, N. N., Meyer, B. & Marx, D. Charge localization dynamics induced by oxygen vacancies on the TiO2 (110) surface. Phys. Rev. Lett. 105, 146405 (2010).

  43. 43.

    Pilger, F. et al. Size control of Pt clusters on CeO2 nanoparticles via an incorporation–segregation mechanism and study of segregation kinetics. ACS Catal. 6, 3688–3699 (2016).

  44. 44.

    DeRita, L. et al. Structural evolution of atomically dispersed Pt catalysts dictates reactivity. Nat. Mater. 18, 746–751 (2019).

  45. 45.

    Ha, M.-A., Baxter, E. T., Cass, A. C., Anderson, S. L. & Alexandrova, A. N. Boron switch for selectivity of catalytic dehydrogenation on size-selected Pt clusters on Al2O3. J. Am. Chem. Soc. 139, 11568–11575 (2017).

  46. 46.

    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).

  47. 47.

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

  48. 48.

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

  49. 49.

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

  50. 50.

    Dudarev, S. L., Botton, G. A., Savrasov, S. Y., Humphreys, C. J. & Sutton, A. P. Electron-energy-loss spectra and the structural stability of nickel oxide: an LSDA + U study. Phys. Rev. B 57, 1505–1509 (1998).

  51. 51.

    Fabris, S., de Gironcoli, S., Baroni, S., Vicario, G. & Balducci, G. Taming multiple valency with density functionals: a case study of defective ceria. Phys. Rev. B 71, 041102 (2005).

  52. 52.

    Naghavi, S. S. et al. Giant onsite electronic entropy enhances the performance of ceria for water splitting. Nat. Commun. 8, 285–291 (2017).

  53. 53.

    Penschke, C. & Paier, J. Reduction and oxidation of Au adatoms on the CeO2(111) surface—DFT + U versus hybrid functionals. Phys. Chem. Chem. Phys. 19, 12546–12558 (2017).

  54. 54.

    Hoover, W. G. Canonical dynamics: equilibrium phase–space distributions. Phys. Rev. A 31, 1695–1697 (1985).

  55. 55.

    Álvarez-Moreno, M. et al. Managing the computational chemistry big data problem: the ioChem-BD platform. J. Chem. Inf. Model. 55, 95–103 (2015).

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Acknowledgements

This research has been supported by the Ministerio de Economía y Competitividad (CTQ2015-68770-R). The authors acknowledge BSC-RES and BIFI for providing generous computational resources. We also thank A. Bruix for critically reading the manuscript, and T. Schäfer for help with the random phase approximation (RPA) methodology.

Author information

N.D. performed the calculations. N.D., M.C.-C. and N.L. analysed the data and prepared the manuscript.

Correspondence to Núria López.

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The authors declare no competing interests.

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Supplementary information

Supplementary Information

Supplementary Notes 1–6, Figs. 1–14, Tables 1–9, video captions 1–4 and references 1–5

Supplementary Video 1

Molecular dynamics simulation of polaron-induced electron transfer between a single Pt atom and its support—a (2 × 2) CeO2 supercell with a 2O termination.

Supplementary Video 2

Molecular dynamics simulation of polaron-induced electron transfer between a single Pt atom and its support—a (2 × 2) CeO2 supercell with a 3O termination.

Supplementary Video 3

Molecular dynamics simulation of polaron-induced electron transfer between a single Pt atom and its support—a (2 × 2) CeO2 supercell with a 4O termination.

Supplementary Video 4

Molecular dynamics simulation of polaron-induced electron transfer between a single Pt atom and its support—a (3 × 3) CeO2 supercell with a 2O termination.

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