期刊
ACS NANO
卷 8, 期 7, 页码 7531-7537出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn502895s
关键词
metal adatoms; nanoparticle growth; adsorption template; metal oxide surface; Fe3O4; magnetite
类别
资金
- Center for Atomic-Level Catalyst Design, an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC0001058]
- Austrian Science Fund [P24925-N20]
- TU Vienna
- Austrian Science Fund doctoral college SOLIDS4FUN [W1243]
- NSF [DMR-1205469]
- Austrian Science Fund (FWF) [P 24925] Funding Source: researchfish
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1205469] Funding Source: National Science Foundation
- Austrian Science Fund (FWF) [W1243, P24925] Funding Source: Austrian Science Fund (FWF)
The atomic-scale mechanisms underlying the growth of Ag on the (root 2x root 2)R45 degrees-Fe3O4(001) surface were studied using scanning tunneling microscopy and density functional theory based calculations. For coverages up to 0.5 ML, Ag adatoms populate the surface exclusively; agglomeration into nanoparticles occurs only with the lifting of the reconstruction at 720 K. Above 03 ML, Ag dusters nucleate spontaneously and grow at the expense of the surrounding material with mild annealing. This unusual behavior results from a kinetic barrier associated with the (root 2x root 2)R45 degrees reconstruction, which prevents adatoms from transitioning to the thermodynamically favorable 3D phase. The barrier is identified as the large separation between stable adsorption sites, which prevents homogeneous duster nucleation and the instability of the Ag dimer against decay to two adatonis. Since the system is dominated by kinetics as long as the (root 2x root 2)R45 degrees reconstruction exists, the growth is not well described by the traditional growth modes. It can be understood, however, as the result of supersaturation within an adsorption template system.
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