Gourhari Jana; Ranita Pal; Sukanta Mondal; Pratim Kumar Chattaraj
Abstract
In order to introduce a new promising material for hydrogen storage application, Nickel (Ni) has been decorated on C12N12 nano-cluster. Firstly, the binding mode of Ni on C12N12 could be thought to be a bridge in between C, N (denoted as C-(μ-Ni)-N) or C, C (denoted as C-(μ-Ni)-C) or N, N (denoted ...
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In order to introduce a new promising material for hydrogen storage application, Nickel (Ni) has been decorated on C12N12 nano-cluster. Firstly, the binding mode of Ni on C12N12 could be thought to be a bridge in between C, N (denoted as C-(μ-Ni)-N) or C, C (denoted as C-(μ-Ni)-C) or N, N (denoted as N-(μ-Ni)-N) resulting in three distinct geometries (abbreviated as XCN, XCC, and XNN isomers, respectively). Owing to the variation in the bridging mode of Ni, the interacting properties with the hydrogen molecule are expected to be different. The spontaneity of formation of Ni-C12N12 and 4Ni-C12N12 in terms of ΔHºf of isodesmic reactions indicate the possibility of getting promising high-energy-density materials (HEDMs). Further, we have investigated whether Ni, being a 3d transition metal, can influence the aromatic behavior of C12N12 nano-cluster. The binding energies and natural bond orbital (NBO) charges have been computed and energy decomposition analysis is carried out for Ni-C12N12 isomers. Decoration of Ni on XCN isomer releases slightly lower energy (~107.4 kcal/mol versus ~58.6 kcal/mol for XNN and XCN respectively). The hydrogen adsorption capacity of the strongest and the weakest Ni-bonded Ni-C12N12 nano-clusters (XNN and XCN isomers, respectively) has also been investigated.
Aristides D. Zdetsis; Eleftherios N. Economou
Abstract
Using suitable Density Functional Theory (DFT) methods and models of various sizes and symmetries, we have obtained the aromaticity pattern of infinite graphene, which is an intrinsically collective effect, by a process of “spatial” evolution. Using a similar process backwards we obtain the ...
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Using suitable Density Functional Theory (DFT) methods and models of various sizes and symmetries, we have obtained the aromaticity pattern of infinite graphene, which is an intrinsically collective effect, by a process of “spatial” evolution. Using a similar process backwards we obtain the distinct aromaticity pattern(s) of finite nanographenes, graphene dots, antidots, and graphene nanoribbons. We have shown that the periodicities in the aromaticity patterns and the band gaps of graphene nanoribbons and carbon nanotubes, are rooted in the fundamental aromaticity pattern of graphene and its size evolution, which is uniquely determined by the number of edge zigzag rings. For graphene antidots the nature of the aromaticity and related properties are largely depended on the degree of antidot passivation. For atomically precise armchair nanoribbons (AGNRs), the aromaticity and the resulting band gaps, besides the number of zigzag rings which determines their widths, are also depended on the finite length of the ribbons, which is usually overlooked in the literature. Thus, we have fully rationalized the aromatic and electronic properties of graphene and various nanographene(s) and we have bridged some of the observed discrepancies for the band gaps in atomically precise AGNRs by judicially introducing the “effective” band gaps as well.
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