Theoretical insight into Cobalt subnano-clusters adsorption on α-Al{sub 2}O{sub 3} (0001)

Journal Article · Wed Feb 15 04:00:00 EST 2017 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2016.11.016· OSTI ID:22658181

Gao, Fen-e ^[1]; Ren, Jun ^[1]; Wang, Qiang ^[2]; Li, Debao ^[2]; Hou, Bo; Jia, Litao ^[2]; Cao, Duanlin ^[1]

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1. College of Chemical Engineering and Environment, North University of China, 030051 Taiyuan (China)
2. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, 030001 Taiyuan (China)

The investigation on the structural stability, nucleation, growth and interaction of cobalt cluster Con(n=2–7) on the α-Al{sub 2}O{sub 3}(0001) surface by using density functional theory methods has been reported. Energetically, the most favorable adsorption sites were identified and the strongest adsorption energy cluster is the tetrahedral Co{sub 4} cluster. On the other hand, the nucleation of Con(n=2–7) clusters on the surface is exothermic and thermodynamically favorable. Moreover, even-odd alternation was found with respect to clusters nucleation as a function of the number of cobalt atoms (for n=1–7). Meanwhile, the Co{sub n} clusters can be adsorbed on the surface stably owing to the charge transfer from Co atoms to Al and O atoms of the Al{sub 2}O{sub 3} substrate. In addition, we establish the crucial importance of monomer, dimer and trimer diffusion on the surface. The diffusion of the monomer cobalt from Al{sup (3)} to O{sup (5)} or O{sup (5)} to Al{sup (4)} site is quite easy on the Al{sub 2}O{sub 3}(0001) surface, whereas the diffusion of the Co{sub 2} dimer is thermodynamically unfavorable by compared with that of the Co adatom and Co{sub 3} trimer. - Graphical abstract: Diffusion process of Co adatom on the α-Al{sub 2}O{sub 3} (0001) surface, Al{sup (3)} site→O{sup (5)} site→Al{sup (4)} site. Potential energy surface for diffusion of a single Co atom from Al{sup (3)} to O{sup (5)} site, and from O{sup (5)} to Al{sup (4)} site on the surface. The activation energy of the two migration processes from Al{sup (3)} to O{sup (5)} and O{sup (5)} to Al{sup (4)} are 0.06 and 0.09 eV, respectively. This implies the monomer is quite mobile on the surface under typical growth conditions.

• OSTI ID: 22658181
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 246; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ACTIVATION ENERGY
ADSORPTION
ALUMINIUM OXIDES
CARBON DIOXIDE
CARBONATES
COBALT
DENSITY FUNCTIONAL METHOD
DIFFUSION
MONOMERS
NUCLEATION
OXIDATION
POTENTIAL ENERGY
SURFACES