Structural changes of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">ZrO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CeO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>solid solutions around the monocl

Yashima, Masatomo; Hirose, T.; Katano, Susumu; Suzuki, Yasuo; Kakihana, Masato; Yoshimura, Masahiro

doi:10.1103/physrevb.51.8018

Cited by 136 publications

(64 citation statements)

References 38 publications

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“…The reciprocal space was sampled with the (6 × 6 × 6) MonkhorstPack mesh of k-points. The m-ZrO 2 bulk was allowed to fully relax until the maximum residual force has been below 0.025 eVÅ −1 , resulting in the structure with a = 5.161Å, b = 5.231Å, c = 5.340Å, and β = 99.6 • , which differs from the experimental data [42,23] by 0.8% at most and is consistent with other computational results. [30,19,18] The m-ZrO 2 surfaces were constructed from the optimized bulk as (1 × 1) two-dimensional slabs of four atomic layers thick (16 ZrO 2 units per computational cell), with the two bottom layers (8 ZrO 2 units) fixed at the ideal bulk positions.…”

Section: Electronic Structure Calculationscontrasting

confidence: 42%

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Bazhenov

Honkala

2016

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Under the water-rich pre-treatment and/or reaction conditions, structure and chemistry of the monoclinic zirconia surfaces are strongly influenced by oxygen vacancies and incorporated water. Here, we report a combined first-principles and atomistic thermodynamics study on the structure and stability of selected surfaces of the monoclinic zirconia. Our results indicate that among the studied surfaces, the most stable (111) surface is the least vulnerable towards oxygen vacancies in contrast to the less stable (011) and (101) surfaces, where formation of oxygen vacancies is energetically more favorable. Furthermore, we present a vigorous, systematic screening of water incorporation onto the studied surfaces. We observe that the greatest stabilization of the surfaces is achieved when a part of the adsorbed water molecules is dissociated. Nevertheless, the importance of water dissociation for achieving the greatest stabilization is high for the less stable (011) and (101) surfaces, while completely hydrated (111) surface is stabilized equally regardless of the water dissociation state. Analysis of the constructed phase diagrams reveals that the (111) surface remains preferably clean and the (011) and (101) surfaces have dissociated water at low coverage under the reactive conditions of T = 600-900 K and p(H 2 O) < 1 bar. Upon temperature decrease and/or pressure increase, all studied surfaces gradually uptake water until fully hydrated. All in all, our findings complement and broaden the existing picture of the structure and stability of the monoclinic zirconia surfaces under the pre-treatment and/or reaction conditions, enabling rationalization of the potential roles of zirconia as a heterogeneous support and a catalyst component.

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Section: Electronic Structure Calculationscontrasting

confidence: 42%

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Bazhenov

Honkala

2016

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“…x C 0.85, a monoclinic phase is produced [22]. At intermediate compositions, various phases (t, t 0 , t 00 , j and t*) have been identified [22][23][24].…”

Section: X-ray Diffractionmentioning

confidence: 98%

Chemoselective Hydrogenation of Cinnamaldehyde over Pd/CeO2–ZrO2 Catalysts

Seemala

Srinivas

2010

Catal Lett

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Selective hydrogenation of cinnamaldehyde over Pd (2 wt%) supported on CeO 2, ZrO 2 and CeO 2 -ZrO 2 catalysts is reported for the first time. In general, the olefinic (C=C) group of cinnamaldehyde is preferentially hydrogenated compared to the carbonyl (C=O) group. This selectivity preference could, however, be altered or reversed by adding alkali additives to the catalyst. The influence of additive on the structure and redox properties of the active sites and correlation of that with selective hydrogenation activity is investigated.

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“…For instance, 1273 K is just below the temperature at which the CeO 2 ZrO 2 phase separates into two phases, i.e., a Zr-rich tetragonal phase and a Ce-rich cubic phase, in the phase diagram. 28) Two phases may therefore start to appear in the CZ support. When coherent interfaces between the two phases are formed in the CZ support, a similar effect to that caused by strain-induced oxygen vacancy formation in the CZP support is expected.…”

Section: ¹1mentioning

confidence: 99%

Enhancement by praseodymium addition of catalytic activity of nickel supported on cerium–zirconium oxide in methane steam reforming

Ishiyama

Kurimoto

Kita

et al. 2014

J. Ceram. Soc. Japan

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The performances in methane steam reforming of Ni catalysts supported on (Ce 0.75 Zr 0.25 )O 2¹y (CZ) and (Ce 0.75/1.025 Zr 0.25/1.025 -Pr 0.025/1.025 )O 2¹y (CZP), which were fired at various temperatures before Ni deposition, were studied. The catalytic activities of the Ni/CZP catalysts were several per cent higher than those of the Ni/CZ catalysts in terms of both CH 4 conversion and H 2 yield. Distinct catalytic activities were observed, even after oxidation, for Ni/CZP with supports pre-fired at 1073 and 1273 K. These observations are discussed in terms of the structural characteristics of the catalysts. The X-ray diffraction profiles and Raman spectra indicated that CZP was a mixture of two phases, i.e., a Pr-rich phase and a Ce-rich cubic phase. The higher catalytic performances of the Ni/CZP catalysts than of the Ni/CZ catalysts and the retention of catalytic activity even after oxidation were attributed to a strained but coherent interface between the phase and the cubic phase, at which oxygen vacancies were easily formed. The Ni/CZ catalyst with the CZ support pre-fired at 1273 K also showed distinct catalytic activity even after oxidation. The activity of Ni/CZ after oxidation was also attributable to an active interface between a Zr-rich tetragonal phase and a Ce-rich cubic phase, similar to the case of the Ni/CZP catalyst.

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Structural changes ofZrO2-CeO2solid solutions around the monocl

Cited by 136 publications

References 38 publications

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Understanding Structure and Stability of Monoclinic Zirconia Surfaces from First-Principles Calculations

Chemoselective Hydrogenation of Cinnamaldehyde over Pd/CeO2–ZrO2 Catalysts

Enhancement by praseodymium addition of catalytic activity of nickel supported on cerium–zirconium oxide in methane steam reforming

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