| 1. |
- Bafekry, A., et al.
(author)
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Theoretical prediction of two-dimensional BC2X (X = N, P, As) monolayers: ab initio investigations
- 2022
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In: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
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Journal article (peer-reviewed)abstract
- In this work, novel two-dimensional BC2X (X = N, P, As) monolayers with X atoms out of the B-C plane, are predicted by means of the density functional theory. The structural, electronic, optical, photocatalytic and thermoelectric properties of the BC2X monolayers have been investigated. Stability evaluation of the BC2X single-layers is carried out by phonon dispersion, ab-initio molecular dynamics (AIMD) simulation, elastic stability, and cohesive energies study. The mechanical properties reveal all monolayers considered are stable and have brittle nature. The band structure calculations using the HSE06 functional reveal that the BC2N, BC2P and BC2As are semiconducting monolayers with indirect bandgaps of 2.68 eV, 1.77 eV and 1.21 eV, respectively. The absorption spectra demonstrate large absorption coefficients of the BC2X monolayers in the ultraviolet range of electromagnetic spectrum. Furthermore, we disclose the BC2N and BC2P monolayers are potentially good candidates for photocatalytic water splitting. The electrical conductivity of BC2X is very small and slightly increases by raising the temperature. Electron doping may yield greater electric productivity of the studied monolayers than hole doping, as indicated by the larger power factor in the n-doped region compared to the p-type region. These results suggest that BC2X (X = N, P, As) monolayers represent a new promising class of 2DMs for electronic, optical and energy conversion systems.
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| 2. |
- Bafekry, A., et al.
(author)
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Ab-initio-driven prediction of puckered penta-like PdPSeX (X=O, S, Te) Janus monolayers : Study on the electronic, optical, mechanical and photocatalytic properties
- 2022
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In: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 582
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Journal article (peer-reviewed)abstract
- A systematic investigation of the structural, mechanical, electronic, and optical properties of puckered penta-like PdPSeX (X=O, S and Te) Janus monolayers has been performed by means of the plane wave density functional theory. It is confirmed that the pentagonal PdPSeX monolayers are dynamically and mechanical stable by means of analysis of their phonon dispersion curves and the Born condition under harmonic approximation, respectively. The PdPSeX Janus monolayers are disclosed as brittle two-dimensional materials (2DMs). The PBE (HSE06)-based calculations exhibit they are indirect semiconductors with bandgap values of 0.65 (1.44) eV, 1.20 (2.02) eV, and 0.98 (1.70) eV for PbPSeO, PbPSeS, and PbPSeTe monolayer, sequentially. The computational results demonstrate the PdPSeTe monolayer as the best suited candidate for visible light absorption and photocatalytic water splitting within the considered pentagonal PdPSeX monolayers. Our ab-initio-based outcomes provide an insight into the fundamental properties of the penta-like PdPSeX Janus structures and surely would motivate further experimental and theoretical studies to reveal the full application potential of this new type of 2DMs.
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| 3. |
- Bafekry, A., et al.
(author)
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Biphenylene monolayer as a two-dimensional nonbenzenoid carbon allotrope: a first-principles study
- 2022
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In: Journal of Physics. - : IOP Publishing Ltd. - 0953-8984 .- 1361-648X. ; 34:1
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Journal article (peer-reviewed)abstract
- In a very recent accomplishment, the two-dimensional form of biphenylene network (BPN) has been fabricated. Motivated by this exciting experimental result on 2D layered BPN structure, herein we perform detailed density-functional theory-based first-principles calculations, in order to gain insight into the structural, mechanical, electronic and optical properties of this promising nanomaterial. Our theoretical results reveal the BPN structure is constructed from three rings of tetragon, hexagon and octagon, meanwhile the electron localization function shows very strong bonds between the C atoms in the structure. The dynamical stability of BPN is verified via the phonon band dispersion calculations. The mechanical properties reveal the brittle behavior of BPN monolayer. The Youngs modulus has been computed as 0.1 TPa, which is smaller than the corresponding value of graphene, while the Poissons ratio determined to be 0.26 is larger than that of graphene. The band structure is evaluated to show the electronic features of the material; determining the BPN monolayer as metallic with a band gap of zero. The optical properties (real and imaginary parts of the dielectric function, and the absorption spectrum) uncover BPN as an insulator along the zz direction, while owning metallic properties in xx and yy directions. We anticipate that our discoveries will pave the way to the successful implementation of this 2D allotrope of carbon in advanced nanoelectronics.
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| 4. |
- Bafekry, A., et al.
(author)
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Investigation of vacancy defects and substitutional doping in AlSb monolayer with double layer honeycomb structure: a first-principles calculation
- 2022
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In: Journal of Physics. - : IOP Publishing Ltd. - 0953-8984 .- 1361-648X. ; 34:6
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Journal article (peer-reviewed)abstract
- The experimental knowledge of the AlSb monolayer with double layer honeycomb structure is largely based on the recent publication (Le Qin et al 2021 ACS Nano 15 8184), where this monolayer was recently synthesized. Therefore, the aim of our research is to consequently explore the effects of substitutional doping and vacancy point defects on the electronic and magnetic properties of the novel hexagonal AlSb monolayer. Besides experimental reports, the phonon band structure and cohesive energy calculations confirm the stability of the AlSb monolayer. Its direct bandgap has been estimated to be 0.9 eV via the hybrid functional method, which is smaller than the value of 1.6 eV of bulk material. The majority of vacancy defects and substitutional dopants change the electronic properties of the AlSb monolayer from semiconducting to metallic. Moreover, the Mg-Sb impurity has demonstrated the addition of ferromagnetic behavior to the material. It is revealed through the calculation of formation energy that in Al-rich conditions, the vacant site of V-Sb is the most stable, while in Sb-rich circumstances the point defect of V-Al gets the title. The formation energy has also been calculated for the substitutional dopants, showing relative stability of the defected structures. We undertook this theoretical study to inspire many experimentalists to focus their efforts on AlSb monolayer growth incorporating different impurities. It has been shown here that defect engineering is a powerful tool to tune the properties of novel AlSb two-dimensional monolayer for advanced nanoelectronic applications.
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| 5. |
- Bafekry, A., et al.
(author)
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Two-dimensional FeTe2 and predicted Janus FeXS (X: Te and Se) monolayers with intrinsic half-metallic character: tunable electronic and magnetic properties via strain and electric field
- 2021
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In: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 23:42, s. 24336-24343
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Journal article (peer-reviewed)abstract
- Driven by the fabrication of bulk and monolayer FeTe2 (ACS Nano, 2020, 14, 11473-11481), we explore the lattice, dynamic stability, electronic and magnetic properties of FeTeS and FeSeS Janus monolayers using density functional theory calculations. The obtained results validate the dynamic and thermal stability of the FeTeS and FeSeS Janus monolayers examined. The electronic structure shows that the FeTe2 bulk yields a total magnetization higher than the FeTe2 monolayer. FeTeS and FeSeS are categorized as ferromagnetic metals due to their bands crossing the Fermi level. So, they can be a good candidate material for spin filter applications. The biaxial compressive strain on the FeTe2 monolayer tunes the bandgap of the spin-down channel in the half-metal phase. By contrast, for FeTeS, the biaxial strain transforms the ferromagnetic metal into a half-metal. The electric field applied to the FeSeS monolayer in a parallel direction transforms the half-metal to a ferromagnetic metal by closing the gap in the spin-down channel.
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