期刊
PARTICUOLOGY
卷 48, 期 -, 页码 2-12出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.partic.2018.08.007
关键词
Nanocrystal Co; Surface free energy; Surface diffusion; Density functional theory
资金
- National Natural Science Foundation of China [91534201, 21476012, 21571012]
- United States Department of Energy, Office of Sciences, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences
Small gas molecules acting as good capping agents play important roles in controlling the morphologies and surface structures of metal nanocrystals. In the present work, the thermodynamic and kinetic roles of H-2 molecules in the morphology of Co nanocrystals were systematically studied by density functional theory (DFT). The Gibbs surface free energies of Co(100), Co(110), and Co(111) at different hydrogen surface coverages were determined by ab initio thermodynamics. The phase diagram of stable H coverage on each plane was obtained and morphology evolution of the Co nanocrystals with various surface hydrogen coverages was predicted by the Wulff construction. Addition of H-2 changes the facet stability, generating diverse morphological Co nuclei. The kinetic role of H-2 in adatom Co surface diffusion at different H coverages was investigated by DFT. The results suggest that surface H hinders Co surface diffusions, except for Co(100) at 0.56 monolayer coverage. The projected density of states gives deeper insight into the electronic structures of Co adatoms with addition of the surface H atoms, which affect its surface diffusion ability. (C) 2019 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
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