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题名: Structural and electronic properties of cobalt carbide Co2C and its surface stability: Density functional theory study
作者: Zhao, Yong-Hui1;  Su, Hai-Yan1;  Sun, Keju1;  Liu, Jinxun1;  Li, Wei-Xue1
关键词: Cobalt carbide ;  Surface structure ;  Stability ;  Density functional theory
刊名: SURFACE SCIENCE
发表日期: 2012-03-01
DOI: 10.1016/j.susc.2011.11.025
卷: 606, 期:5-6, 页:598-604
收录类别: SCI
文章类型: Article
WOS标题词: Science & Technology ;  Physical Sciences
类目[WOS]: Chemistry, Physical ;  Physics, Condensed Matter
研究领域[WOS]: Chemistry ;  Physics
英文摘要: Density functional theory calculations have been performed to investigate the structural and electronic properties of bulk Co2C and the stability of low index Co2C surfaces. We found that the formation of Co2C is exothermic with the formation energy of -0.81 eV/Co2C with respect to Co under the presence of syngas (mixture of CO and H-2). While formed Co2C can be decomposed further to metal Co and graphite carbon with modest energy gain of 0.37 eV/Co2C. This suggests that Co2C is only metastable in Fischer-Tropsch synthesis, which agrees well with experimental findings. The density of states (DOSs) reveals that the Co2C is paramagnetic and strong metallic-like. The difference of charge density analysis indicates that the bond of Co2C is of the mixtures of metallic, covalent, and ionic properties. A variety of low index Co2C surfaces with different terminations are studied. We find that the surface energy of low index stoichiometric Co2C highly relies on the surface area, the number of coordination of surface atoms and the surface dipole, with the decreased stability order of (101) > (011) > (010) > (110) > (100) > (001) = (111). Our results indicate that under Co-poor condition, the formation of non - stoichiometric surface (011) and (111) without terminated cobalt is energetically more favorable, while under Co-rich condition the formation of non - stoichiometric (111) surface with cobalt overlayer are preferential. (C), 2011 Elsevier B.V. All rights reserved.
关键词[WOS]: FISCHER-TROPSCH SYNTHESIS ;  TRANSITION-METAL CARBIDES ;  CHAIN GROWTH-MECHANISM ;  AUGMENTED-WAVE METHOD ;  CATALYTIC-PROPERTIES ;  TUNGSTEN CARBIDE ;  ACTIVATED CARBON ;  HIGHER ALCOHOLS ;  ADSORPTION ;  SYNGAS
语种: 英语
WOS记录号: WOS:000300920600005
Citation statistics: 
内容类型: 期刊论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/143103
Appears in Collections:中国科学院大连化学物理研究所_期刊论文

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作者单位: 1.Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Peoples R China

Recommended Citation:
Zhao, Yong-Hui,Su, Hai-Yan,Sun, Keju,et al. Structural and electronic properties of cobalt carbide Co2C and its surface stability: Density functional theory study[J]. SURFACE SCIENCE,2012,606(5-6):598-604.
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