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Volumn 298, Issue 5594, 2002, Pages 811-814

The effect of size-dependent nanoparticle energetics on catalyst sintering

Author keywords

[No Author keywords available]

Indexed keywords

ADSORPTION; CALORIMETRY; PARTICLE SIZE ANALYSIS; SINTERING;

EID: 0037174650     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.1075094     Document Type: Article
Times cited : (928)

References (43)
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    • P. Wynblatt, N. A. Gjostein, in Progess in Solid State Chemistry, J. O. McCaldin, G. A. Somorjai, Eds. (Elsevier Science, Amsterdam, 1975), vol. 9, pp. 21-58.
    • (1975) Progess in Solid State Chemistry , vol.9 , pp. 21-58
    • Wynblatt, P.1    Gjostein, N.A.2
  • 6
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    • C. H. Bartholomew, G. A. Fuentes, Eds. (Elsevier Science, Amsterdam)
    • G. A. Fuentes, E. Salinas-Rodriguez, in Catalyst Deactivation, C. H. Bartholomew, G. A. Fuentes, Eds. (Elsevier Science, Amsterdam, 1997), pp. 573-583.
    • (1997) Catalyst Deactivation , pp. 573-583
    • Fuentes, G.A.1    Salinas-Rodriguez, E.2
  • 7
    • 34447282072 scopus 로고    scopus 로고
    • C. H. Bartholomew, G. A. Fuentes, Eds. (Elsevier Science, Amsterdam)
    • C. H. Bartholomew, in Catalyst Deactivation, C. H. Bartholomew, G. A. Fuentes, Eds. (Elsevier Science, Amsterdam, 1997), pp. 585-592.
    • (1997) Catalyst Deactivation , pp. 585-592
    • Bartholomew, C.H.1
  • 12
    • 2142834668 scopus 로고    scopus 로고
    • note
    • Because the only degrees of freedom of the metal atoms in these clusters are vibrations, the entropic contributions to the free energy are small and differ very little with cluster size. Thus, Eq. 1 is also often applied to describe the size dependence of internal energy as well as free energy. Generally, γ is assumed to be independent of particle radius at the value for bulk metal (3, 4, 13-15).
  • 17
    • 2142840949 scopus 로고    scopus 로고
    • note
    • The assumption of a constant number density of islands is probably slightly incorrect in that their number generally increases weakly with coverage in this range for such systems (13, 41). Correcting for this would cause the measured decrease in stability with radius to be even more dramatic than shown.
  • 19
    • 2142683039 scopus 로고    scopus 로고
    • note
    • 2 (42)] gives even poorer agreement with experiment. Using Eq. 1 here neglects the energy of the flat face of the hemisphere, which is equivalent to setting the Pb/MgO adhesion energy at this face equal to the Pb-Pb adhesion energy. [if the Pb/MgO adhesion energy were zero, the factor of 2 in Eq. 1 would instead be 3. In reality, the needed correction is much smaller (16).]
  • 25
    • 2142848613 scopus 로고    scopus 로고
    • note
    • DePristo estimated that relation empirically by extrapolating between measured energies of: the gaseous dimer (CN = 1), a (111) surface (CN = 9), and the bulk (CN = 12). Furthermore, we used DePristo's relation to estimate the errors in the MBA model of Fig. 1 and found that the errors due to the decrease in bond energy with CN nearly compensate for the errors associated with extrapolating between only the most stable clusters, further justifying its use.
  • 27
    • 2142734878 scopus 로고    scopus 로고
    • note
    • tot.
  • 28
    • 2142723481 scopus 로고    scopus 로고
    • note
    • μ(∞)}/kT in Taylor series and neglected all but the first two terms. This is equivalent to assuming that μ(R) - μ(∞) is small compared to kT. Inspection of the heat data in Fig. 1 proves that this is clearly not the case below 1000 K for particles with a radius of a few nanometers.
  • 37
    • 2142782896 scopus 로고    scopus 로고
    • note
    • 2(110) under similar deposition conditions was estimated by scanning tunneling microscopy (13) and high-resolution scanning electron microscopy (33) to be about 1 nm. We used a slightly smaller average size because those techniques could have missed the smallest particles.
  • 39
    • 2142731143 scopus 로고    scopus 로고
    • thesis, University of Washington, Seattle, WA
    • S. C. Parker, thesis, University of Washington, Seattle, WA (2000).
    • (2000)
    • Parker, S.C.1
  • 43
    • 2142793073 scopus 로고    scopus 로고
    • note
    • We thank the U.S. Department of Energy, Office of Basic Energy Sciences, Chemical Sciences Division, for support of this work. D.E.S. thanks NSF and the University of Washington Center for Nanotechnology for an IGERT Fellowship.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.