Abstract
The electronic structures, magnetization and quantum transport properties of edge chlorinated nanographenes (Cl NGRs) (C1–C3) functionalized with conductive metal adatoms (Al, Au and Cu) has been investigated by means of density functional theory (DFT) with periodic boundary conditions and plane wave basis functions. The adsorption energy results depict weak chemisorption and strong physisorption for Au adsorption for C1, while C2 and C3 show strong chemisorption towards the studied metals. The role of dispersion forces has also been studied with an empirical classical model. The results show that the metal clusters avoid hollow sites on the Cl NGRs surface and favor atop and bond sites. The net magnetic moment of 0.73 μB is observed for the (Cl NGRs–metals) system and is in reasonable agreement with the previous calculations carried out on graphene nanoribbons. The TDDFT calculations predict that the absorption spectra for metal dimer–Cl NGRs lie in the visible region. The predictive electrical conductivity of these systems suggests that the metal adatoms play an important role in the transport properties of devices and can be used for thermoelectric applications.
Highlights
Graphene, a monolayer of carbon atoms, arranged in honeycomb network has attracted immense interest[1,2,3] due to its optoelectronic, transport[3,4,5,6,7,8] and extraordinary physical properties, which is governed by the size of the sheet and the nature of its periphery.[9,10] Graphene is a zero-gap semiconductor with a point-like Fermi surface and a linear dispersion at the Fermi level
In C4–Au and C5–Au complexes, we have observed that the bond distances between Au and nanographenes is 2.289 and 2.799 Arespectively. These result indicate that the interface of the gold clusters and nanographenes are stabilized when the metal atoms are just above the carbon atoms which has already been predicted in the previous studies.31b,32b As the interaction between the metal adatoms affect the electronic properties of chlorinated nanographenes (Cl NGRs)–metal systems, so two metal atoms has introduced for these Cl NGRs systems
On the basis of density functional theory (DFT) calculations, it was found that all the studied complexes show strong chemical bonding with ClNGRs, while the adsorption of Au on C1 is between weak chemisorption and strong physisorption
Summary
A monolayer of carbon atoms, arranged in honeycomb network has attracted immense interest[1,2,3] due to its optoelectronic, transport[3,4,5,6,7,8] and extraordinary physical properties, which is governed by the size of the sheet and the nature of its periphery.[9,10] Graphene is a zero-gap semiconductor with a point-like Fermi surface and a linear dispersion at the Fermi level. Novel and interesting phenomena result in the nanoscales of metallic nanowires which is different from their bulk materials.[33,34,35] The effect on quantized conductance has been veri ed by numerous nanoscale systems experimentally,[32] and the electronic structure, ballistic quantum transport properties, and e–pH coupling for atomic wires of Al and coinage metals has already been reported previously.[36] A theoretical investigation for coinage metal atoms (Cu, Ag, Au) and clusters on graphite and graphene[36,37,38] were carried out to observe the interaction, charge transfer, distances, nature of binding between graphene and metal, as well as the electronic and structural properties for understanding the metal–graphene interaction for the development of hybrid materials with speci c properties. For complexes C4–C7, we have reported the optimized structures of only reliable results in ESI.† The optimized results for C4, C5, C4–Au and C5–Au complexes are given in ESI Fig. 1.† The electronic and optical data of these structures are given in ESI Table 1 and ESI Table 2† respectively
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