An ab initio analysis of adsorption and diffusion of silver atoms on alumina surfaces

Meyer, Randall J.; Ge, Qingfeng; Lockemeyer, John R.; Yeates, Randy; Lemanski, Michael; Reinalda, Donald; Neurock, Matthew

doi:10.1016/j.susc.2006.09.028

Cited by 58 publications

(73 citation statements)

References 97 publications

(168 reference statements)

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“…These values are in excellent agreement with experimental data (as indicated in parentheses) [59]. Our lattice parameter values are also consistent with previously-reported DFT-GGA results [60][61][62][63][64].…”

Section: Methodssupporting

confidence: 92%

Density Functional Theory Study of Arsenate Adsorption onto Alumina Surfaces

2018

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Atomistic modeling of mineral-water interfaces offers a way of confirming (or refuting) experimental information about structure and reactivity. Molecular-level understanding, such as orbital-based descriptions of bonding, can be developed from charge density and electronic structure analysis. First-principles calculations can be used to identify weaknesses in empirical models. This provides direction on how to propose more robust representations of systems of increasing size that accurately represent the underlying physical factors governing reactivity. In this study, inner-sphere complex geometries of arsenate on hydrated alumina surfaces are modeled at the density functional theory (DFT)-continuum solvent level. According to experimental studies, arsenate binds to alumina surfaces in a bidentate binuclear (BB) fashion. While the DFT calculations support the preference of the BB configuration, the optimized geometries show distortion from the ideal tetrahedral geometry of the arsenic atom. This finding suggests that steric factors, and not just coordination arguments, influences reactivity. The O surf -As-O surf angle for the more favorable arsenate configurations is closest to the ideal tetrahedral angle of 109.5 • . Comparing the results of arsenate adsorption using a small cluster model with a periodic slab model, we report that the two model geometries yield results that differ qualitatively and quantitatively. This relates the steric factors and rigidity of the surface models.

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Section: Methodssupporting

confidence: 92%

Density Functional Theory Study of Arsenate Adsorption onto Alumina Surfaces

2018

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“…No oxidation was observed for the Ag nanocrystal after the thermal treatments in Ar. The ripening of Ag particles/clusters has been studied on other surfaces, e.g., Ag (111) [40], alumina [41], glass and oxide-coated glass [42], and CNTs [43], or when embedded in soda glass [44] and polymer films [45]. Two possible mechanisms, Ostwald ripening and particle migration and coalescence [46,47], are believed to be responsible for the ripening process.…”

Section: Resultsmentioning

confidence: 99%

Facile, noncovalent decoration of graphene oxide sheets with nanocrystals

et al. 2009

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Facile dry decoration of graphene oxide sheets with aerosol Ag nanocrystals synthesized from an arc plasma source has been demonstrated using an electrostatic force directed assembly technique at room temperature. The Ag nanocrystal-graphene oxide hybrid structure was characterized by transmission electron microscopy (TEM) and selected area diffraction. The ripening of Ag nanocrystals on a graphene oxide sheet was studied by consecutive TEM imaging of the same region on a sample after heating in Ar at elevated temperatures of 100 °C, 200 °C, and 300 °C. The average size of Ag nanocrystals increased and the number density decreased after the annealing process. In particular, migration and coalescence of Ag nanocrystals were observed at a temperature as low as 100 °C, suggesting a van der Waals interaction between the Ag nanocrystal and the graphene oxide sheet. The availability of affordable graphene-nanocrystal structures and their fundamental properties will open up new opportunities for nanoscience and nanotechnology and accelerate their applications.

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“…We show that the theoretical results are indeed consistent with the few experimental results on sintering of methanol synthesis catalyst. Our starting points are the two generic mechanisms for metal particle growth in heterogeneous catalysts [21][22][23][24]: (i) particle migration and coalescence (PMC) and (ii) Ostwald ripening (OR). In the former mechanism, entire metal particles are translated and eventually merge upon contact, whereas the latter mechanism is characterized by mass transport between the metal particles.…”

Section: Introductionmentioning

confidence: 99%