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Equilibrium oxygen storage capacity of ultrathin CeO2-δ depends non-monotonically on large biaxial strain

Balaji Gopal, Chirranjeevi; García-Melchor, Max; Lee, Sang Chul; Shi, Yezhou; Shavorskiy, Andrey LU ; Monti, Matteo; Guan, Zixuan; Sinclair, Robert; Bluhm, Hendrik and Vojvodic, Aleksandra, et al. (2017) In Nature Communications 8.
Abstract

Elastic strain is being increasingly employed to enhance the catalytic properties of mixed ion-electron conducting oxides. However, its effect on oxygen storage capacity is not well established. Here, we fabricate ultrathin, coherently strained films of CeO2-δ between 5.6% biaxial compression and 2.1% tension. In situ ambient pressure X-ray photoelectron spectroscopy reveals up to a fourfold enhancement in equilibrium oxygen storage capacity under both compression and tension. This non-monotonic variation with strain departs from the conventional wisdom based on a chemical expansion dominated behaviour. Through depth profiling, film thickness variations and a coupled photoemission-thermodynamic analysis of space-charge... (More)

Elastic strain is being increasingly employed to enhance the catalytic properties of mixed ion-electron conducting oxides. However, its effect on oxygen storage capacity is not well established. Here, we fabricate ultrathin, coherently strained films of CeO2-δ between 5.6% biaxial compression and 2.1% tension. In situ ambient pressure X-ray photoelectron spectroscopy reveals up to a fourfold enhancement in equilibrium oxygen storage capacity under both compression and tension. This non-monotonic variation with strain departs from the conventional wisdom based on a chemical expansion dominated behaviour. Through depth profiling, film thickness variations and a coupled photoemission-thermodynamic analysis of space-charge effects, we show that the enhanced reducibility is not dominated by interfacial effects. On the basis of ab initio calculations of oxygen vacancy formation incorporating defect interactions and vibrational contributions, we suggest that the non-monotonicity arises from the tetragonal distortion under large biaxial strain. These results may guide the rational engineering of multilayer and core-shell oxide nanomaterials.

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Nature Communications
volume
8
publisher
Nature Publishing Group
external identifiers
  • scopus:85019563217
  • wos:000401509500001
ISSN
2041-1723
DOI
10.1038/ncomms15360
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English
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yes
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512093d4-a02a-44da-9daa-277d82840435
date added to LUP
2017-06-09 09:09:43
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2018-01-07 12:06:49
@article{512093d4-a02a-44da-9daa-277d82840435,
  abstract     = {<p>Elastic strain is being increasingly employed to enhance the catalytic properties of mixed ion-electron conducting oxides. However, its effect on oxygen storage capacity is not well established. Here, we fabricate ultrathin, coherently strained films of CeO<sub>2-δ</sub> between 5.6% biaxial compression and 2.1% tension. In situ ambient pressure X-ray photoelectron spectroscopy reveals up to a fourfold enhancement in equilibrium oxygen storage capacity under both compression and tension. This non-monotonic variation with strain departs from the conventional wisdom based on a chemical expansion dominated behaviour. Through depth profiling, film thickness variations and a coupled photoemission-thermodynamic analysis of space-charge effects, we show that the enhanced reducibility is not dominated by interfacial effects. On the basis of ab initio calculations of oxygen vacancy formation incorporating defect interactions and vibrational contributions, we suggest that the non-monotonicity arises from the tetragonal distortion under large biaxial strain. These results may guide the rational engineering of multilayer and core-shell oxide nanomaterials.</p>},
  articleno    = {15360},
  author       = {Balaji Gopal, Chirranjeevi and García-Melchor, Max and Lee, Sang Chul and Shi, Yezhou and Shavorskiy, Andrey and Monti, Matteo and Guan, Zixuan and Sinclair, Robert and Bluhm, Hendrik and Vojvodic, Aleksandra and Chueh, William C.},
  issn         = {2041-1723},
  language     = {eng},
  month        = {05},
  publisher    = {Nature Publishing Group},
  series       = {Nature Communications},
  title        = {Equilibrium oxygen storage capacity of ultrathin CeO<sub>2-δ</sub> depends non-monotonically on large biaxial strain},
  url          = {http://dx.doi.org/10.1038/ncomms15360},
  volume       = {8},
  year         = {2017},
}