Low-Dimensional Carbon Based Systems: Firstprinciples Studies
Rui Pang, Yangfan Shao, Qian Wang, Xiji Shao, Xingqiang Shi*
Department of physics, South University of science and technology of China
*[email protected]
Introduction
Graphene/MoS2 for Lithium storage
.
Carbon based materials provide the most abundant structural varieties.
This property generates a mount of complex phenomenon and gives a
great deal of opportunities to realize novel functionalities. Our works
mainly focus on the organic/metal interfaces, lithium storages, and novel
two dimensional materials.
Magnetism on reconstructed organic/metal
interfaces
Graphene/MoS2 composites exhibit excellent Li-storage capability. Bandgap opening of graphene is found in Gr/Li(n)/MoS2; the band-gap is
enlarged with the increasing number of intercalated Li atoms. And, the
Dirac cone feature of graphene is always preserved.
(a)
(b)
Due to strong interactions between ferromagnetic metal surfaces and
fullerenes, reconstruction could happen at the interface of C60/Fe(100)
and C60/Ni(111). Fig. (a) shows the fullerene creates a 4-atom-hole at
Fe(100) and an antiferromagnetic coupling appears between the fullerene
and the substrate. Fig. (b) shows the fullerene remove seven atoms on
Ni(111) and have a remarkable enhance on the spin polarization of the
molecule and a distinct reduce on the magnetic coupling and
magnetocrystalline anisotropy energy (MAE) of the two outer most
substrate layers.
Molecular Precursors-Induced Surface
Reconstruction
Two reasons for the high Li-storage capability: 1) The left panel, the
binding energy per Li increase with increasing number of Li atoms; 2) the
right panel, for Li-atom diffusion in the graphene/MoS2 interface, the
diffusion barrier is small, ~0.25eV.
2-D iron-carbides (Fe-C)
Unreconstructed
Reconstructed
We demonstrate that the Pt(111) surface reconstruction occurred at
the earlier stages of graphene formation when there were (partial)
hydrogens remain in the hydrogenated precursors of C2H4 and planar
C60H30 molecule.
The reason is attributed to the fact that the energy gain, from the
strengthened Pt−C partial sp3−like bonding for C with partial H (than
Pt−Gr bonding), compensates for the energy cost of formation surface
vacancies and makes the reconstruction feasible (especially at elevated
temperatures).
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We propose and demonstrate that the square-lattices observed in the
experiment were monolayer iron-carbides (Fe-C) but not pure Fe, from
the square-lattice shape, Fe-Fe distance, energetic and dynamic stability
considerations. High spin-polarization and out-of-plane magnetization are
found in this system.