Transfer doping of a metallic carbon nanotube and graphene on metal surfaces
Transfer doping of a metallic carbon nanotube and graphene on metal surfaces
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DOI：
10.1103/physrevb.83.155435
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发表时间：
2011-04
影响因子：
3.7
通讯作者：
M. Hasegawa;K. Nishidate
中科院分区：
文献类型：
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作者：
M. Hasegawa;K. Nishidate
在本文中，我们展示了一个扶手椅（10，10）单壁碳纳米管（SWNT）和石墨烯吸附在金属表面的电子结构的修改系统的调查结果。采用基于密度泛函理论（DFT）的第一性原理计算方法研究了这些纳米材料吸附在Al、贵金属（Ag、Cu和Au）以及过渡金属（Rh、Pd、Ir和Pt）的fcc（111）表面上的转移掺杂。我们证实，单壁碳纳米管与铝和贵金属的表面弱相互作用（物理吸附），而它强烈键合到过渡金属表面（化学吸附）。石墨烯吸附在这些金属表面上的重新调查，发现是相似的，除了Ir和Pt基板，其中的相互作用是弱的情况下的Al和贵金属基板。一个唯象模型也开发的基础上的刚性带图片适当的物理吸附。该模型提供了费米能级位移和功函数差之间的关系，并且可以方便地用于解释单壁碳纳米管和石墨烯在金属表面上的转移掺杂的DFT结果。我们还确定了石墨烯π轨道和金属价态之间的杂化对费米能级位移的影响，并发现杂化诱导了狄拉克点附近的线性色散带相对于其他带的额外向下位移。
In this paper we show the results of systematic investigations for the electronic-structure modifications of an armchair (10,10) single-walled carbon nanotube (SWNT) and graphene adsorbed on metal surfaces. The first-principles calculations based on the density-functional theory (DFT) were used to investigate transfer doping of these nanomaterials adsorbed on the fcc (111) surfaces of Al, noble metals (Ag, Cu, and Au), and transition metals (Rh, Pd, Ir, and Pt). We confirmed that the SWNT weakly interacts with the surfaces of Al and the noble metals (physisorption), while it strongly bonds to the transition-metal surfaces (chemisorption). The graphene adsorption on these metal surfaces is reinvestigated and found to be similar except for the Ir and Pt substrates, for which the interaction is weak as in the case of Al and the noble metal substrates. A phenomenological model is also developed on the basis of the rigid-band picture appropriate to physisorption. This model provides a relation between the Fermi-level shift and work-function difference and can conveniently be used in interpreting the DFT results for the transfer doping of both a SWNT and graphene on metal surfaces. We also identify the effect of hybridization between the graphene π orbitals and metallic valence states on the Fermi-level shift and find that the hybridization induces an extra downward shift of the linear-dispersion bands near the Dirac point relative to the other bands.