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Shayeganfar F, Ramazani A, Habibiyan H, Diznab MR. Publisher Correction: Terahertz linear/non-linear anomalous Hall conductivity of moiré TMD hetero-nanoribbons as topological valleytronics materials. Sci Rep 2024; 14:6179. [PMID: 38485974 PMCID: PMC10940625 DOI: 10.1038/s41598-024-56021-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2024] Open
Affiliation(s)
- Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Hamidreza Habibiyan
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mohammad Rafiee Diznab
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
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Momen F, Shayeganfar F, Ramazani A. Boron-rich hybrid BCN nanoribbons for highly ambient uptake of H 2S, HF, NH 3, CO, CO 2 toxic gases. Phys Chem Chem Phys 2024; 26:5262-5288. [PMID: 38264800 DOI: 10.1039/d3cp04767a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Nanomaterials-based gas sensors are widely applied for the monitoring and fast detection of hazardous gases owing to their sensitivity and selectivity. Hydrogen sulfide (H2S), hydrogen fluoride (HF), ammonia (NH3), and carbon monoxide/dioxide (CO/CO2) produced from petroleum fields, sewage, mines, and gasoline are harmful for both human life and environment. With an increase in the emission of these toxic compounds, their real-time monitoring and efficient adsorbent application and storage are very necessary. To this end, we investigated the adsorption characteristic and sensitivity factor of these five toxic gases on armchair and zigzag hybrid boron-carbon-nitride (BCN) nanoribbons with/without boron-rich (B-rich) defects using first principle calculation, where 25%, 33%, and 50% carbon concentration were considered. Our findings reveal that B-rich nanoribbons have strong adsorption energy, charge transfer, and structural deformation owing to the double acceptor of B-rich defects. Moreover, the zigzag and armchair forms of these hybrid BCN nanoribbons show physical adsorption, altering their band gap and phase transition after adsorbing these toxic gases, where B-rich nanoribbons possess high sensitivity to NH3 and CO among other gases. Furthermore, B-rich hybrid nanoribbons have higher CO2 adsorption energy than the standard free energy of CO2 at room temperature. This study suggests that hybrid BCN nanoribbons and B-rich defected structures can be good candidates for the uptake and storage of toxic gases, helping experimental groups to design efficient ambient gas sensors.
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Affiliation(s)
- Fatemeh Momen
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Torkashvand Z, Shayeganfar F, Ramazani A. Nanomaterials Based Micro/Nanoelectromechanical System (MEMS and NEMS) Devices. Micromachines (Basel) 2024; 15:175. [PMID: 38398905 PMCID: PMC10890696 DOI: 10.3390/mi15020175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 02/25/2024]
Abstract
The micro- and nanoelectromechanical system (MEMS and NEMS) devices based on two-dimensional (2D) materials reveal novel functionalities and higher sensitivity compared to their silicon-base counterparts. Unique properties of 2D materials boost the demand for 2D material-based nanoelectromechanical devices and sensing. During the last decades, using suspended 2D membranes integrated with MEMS and NEMS emerged high-performance sensitivities in mass and gas sensors, accelerometers, pressure sensors, and microphones. Actively sensing minute changes in the surrounding environment is provided by means of MEMS/NEMS sensors, such as sensing in passive modes of small changes in momentum, temperature, and strain. In this review, we discuss the materials preparation methods, electronic, optical, and mechanical properties of 2D materials used in NEMS and MEMS devices, fabrication routes besides device operation principles.
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Affiliation(s)
- Ziba Torkashvand
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran 15875-4413, Iran; (Z.T.); (F.S.)
| | - Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran 15875-4413, Iran; (Z.T.); (F.S.)
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Shayeganfar F, Ramazani A, Habibiyan H, Rafiee Diznab M. Terahertz linear/non-linear anomalous Hall conductivity of moiré TMD hetero-nanoribbons as topological valleytronics materials. Sci Rep 2024; 14:1581. [PMID: 38238394 PMCID: PMC10796390 DOI: 10.1038/s41598-024-51721-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 01/09/2024] [Indexed: 01/22/2024] Open
Abstract
Twisted moiré van der Waals heterostructures hold promise to provide a robust quantum simulation platform for strongly correlated materials and realize elusive states of matter such as topological states in the laboratory. We demonstrated that the moiré bands of twisted transition metal dichalcogenide (TMD) hetero-nanoribbons exhibit non-trivial topological order due to the tendency of valence and conduction band states in K valleys to form giant band gaps when spin-orbit coupling (SOC) is taken into account. Among the features of twisted WS[Formula: see text]/MoS[Formula: see text] and WSe[Formula: see text]/MoSe[Formula: see text], we found that the heavy fermions associated with the topological flat bands and the presence of strongly correlated states, enhance anomalous Hall conductivity (AHC) away from the magic angle. By band analysis, we showed that the topmost conduction bands from the ± K-valleys are perfectly flat and carry a spin/valley Chern number. Moreover, we showed that the non-linear anomalous Hall effect in moiré TMD hetero-nanoribbons can be used to manipulate terahertz (THz) radiation. Our findings establish twisted heterostructures of group-VI TMD nanoribbons as a tunable platform for engineering topological valley quantum phases and THz non-linear Hall conductivity.
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Affiliation(s)
- Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Hamidreza Habibiyan
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mohammad Rafiee Diznab
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
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Rezayei E, Beheshtian J, Shayeganfar F, Ramazani A. Correction to: Fundamental mechanisms of hexagonal boron nitride sensing of dopamine, tryptophan, ascorbic acid, and uric acid by first‑principles study. J Mol Model 2022; 28:199. [PMID: 35731285 DOI: 10.1007/s00894-022-05174-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Elham Rezayei
- Department of Chemistry, Shahid Rajaee Teacher Training University, Tehran, Iran
| | - Javad Beheshtian
- Department of Chemistry, Shahid Rajaee Teacher Training University, Tehran, Iran.
| | - Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Ali Ramazani
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, USA
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Shayeganfar F, Shahsavari R. Deep Learning Method to Accelerate Discovery of Hybrid Polymer-Graphene Composites. Sci Rep 2021; 11:15111. [PMID: 34301976 PMCID: PMC8302643 DOI: 10.1038/s41598-021-94085-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 07/05/2021] [Indexed: 11/17/2022] Open
Abstract
Interfacial encoded properties of polymer adlayers adsorbed on the graphene (GE) and silicon dioxide (SiO2) have been constituted a scaffold for the creation of new materials. The holistic understanding of nanoscale intermolecular interaction of 1D/2D polymer assemblies on substrate is the key to bottom-up design of molecular devices. We develop an integrated multidisciplinary approach based on electronic structure computation [density functional theory (DFT)] and big data mining [machine learning (ML)] in parallel with neural network (NN) and statistical analysis (SA) to design hybrid polymers from assembly on substrate. Here we demonstrate that interfacial pressure and structural deformation of polymer network adsorbed on GE and SiO2 offer unique directions for the fabrication of 1D/2D polymers using only a small number of simple molecular building blocks. Our findings serve as the platform for designing a wide range of typical inorganic heterostructures, involving noncovalent intermolecular interaction observed in many nanoscale electronic devices.
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Affiliation(s)
- Farzaneh Shayeganfar
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA. .,Department of Physics and Energy Engineering, Amirkabir University of Technology, 15916-3967, Tehran, Iran.
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Faghihnasiri M, Mousavi SH, Shayeganfar F, Ahmadi A, Beheshtian J. Hydrogenated Ψ-graphene as an ultraviolet optomechanical sensor. RSC Adv 2020; 10:26197-26211. [PMID: 35519744 PMCID: PMC9055300 DOI: 10.1039/d0ra03104f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/22/2020] [Indexed: 01/16/2023] Open
Abstract
PSI (ψ)-graphene is a dynamically and thermally stable two-dimensional (2D) allotrope of carbon composed of 5-6-7 carbon rings. Herein, we study the opto/mechanical behavior of two graphene allotropes, Ψ-graphene and its hydrogenated form, Ψ-graphane under uniaxial and biaxial strain using density functional theory (DFT) calculations. We calculated the elastic constants and second Piola-Kirchhoff (PK2) stresses, in which both nanostructures indicate a similar elasticity behavior to graphene. Also, the plasmonic behavior of these structures in response to various strains has been studied. As a result, plasmonic peaks varied up to about 2 eV under strain. Our findings reveal that these two structures have a large peak in the ultraviolet (UV) region and can be tuned by different applied strain. In addition, Ψ-graphene has smaller peaks in the IR and UV regions. Therefore, both Ψ-graphene and Ψ-graphane can be used as UV optomechanical sensors, whereas Ψ-graphene could be used as an infrared (IR) and visible sensor. PSI (ψ)-graphene is a dynamically and thermally stable two-dimensional (2D) allotrope of carbon composed of 5-6-7 carbon rings.![]()
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Affiliation(s)
- Mahdi Faghihnasiri
- Computational Materials Science Laboratory, Nano Research and Training Center, NRTC Iran.,Faculty of Science, Shahid Rajaee Teacher Training 16875-163 Tehran Iran,
| | - S Hannan Mousavi
- Computational Materials Science Laboratory, Nano Research and Training Center, NRTC Iran
| | - Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology Tehran Iran
| | - Aidin Ahmadi
- Computational Materials Science Laboratory, Nano Research and Training Center, NRTC Iran
| | - Javad Beheshtian
- Faculty of Science, Shahid Rajaee Teacher Training 16875-163 Tehran Iran,
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Faghihnasiri M, Beheshtian J, Shayeganfar F, Shahsavari R. Phase transition and mechanical properties of cesium bismuth silver halide double perovskites (Cs 2AgBiX 6, X = Cl, Br, I): a DFT approach. Phys Chem Chem Phys 2020; 22:5959-5968. [PMID: 32123885 DOI: 10.1039/c9cp05342e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double perovskite-based silver and bismuth Cs2AgBiX6 (X = Cl, Br, I) have shown a bright future for the development of low-risk photovoltaic devices due to their high stability and non-toxicity of their elements, unlike Pb-based perovskites. Despite the great focus on the optoelectronic properties of Cs2AgBiX6 double perovskites, there are limited studies on the behavior of their structural properties. Herein, we carefully examined the cubic structure of Cs2AgBiX6 double perovskites, identifying a pseudo-cubic (ps-cubic) phase, which is similar to the initial cubic phase. The observed pseudo-cubic phase is more consistent with previous experimental results demonstrating higher elastic properties, which are useful for designing optoelectronic devices.
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Affiliation(s)
- Mahdi Faghihnasiri
- Computational Materials Science Laboratory, Nano Research and Training Center, NRTC, Iran
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Amiri M, Beheshtian J, Shayeganfar F, Faghihnasiri M, Shahsavari R, Ramazani A. Electro-Optical Properties of Monolayer and Bilayer Pentagonal BN: First Principles Study. Nanomaterials (Basel) 2020; 10:nano10030440. [PMID: 32121427 PMCID: PMC7153586 DOI: 10.3390/nano10030440] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/25/2020] [Accepted: 02/25/2020] [Indexed: 01/29/2023]
Abstract
Two-dimensional hexagonal boron nitride (hBN) is an insulator with polar covalent B-N bonds. Monolayer and bilayer pentagonal BN emerge as an optoelectronic material, which can be used in photo-based devices such as photodetectors and photocatalysis. Herein, we implement spin polarized electron density calculations to extract electronic/optical properties of mono- and bilayer pentagonal BN structures, labeled as B2N4, B3N3, and B4N2. Unlike the insulating hBN, the pentagonal BN exhibits metallic or semiconducting behavior, depending on the detailed pentagonal structures. The origin of the metallicity is attributed to the delocalized boron (B) 2p electrons, which has been verified by electron localized function and electronic band structure as well as density of states. Interestingly, all 3D networks of different bilayer pentagonal BN are dynamically stable unlike 2D structures, whose monolayer B4N2 is unstable. These 3D materials retain their metallic and semiconductor nature. Our findings of the optical properties indicate that pentagonal BN has a visible absorption peak that is suitable for photovoltaic application. Metallic behavior of pentagonal BN has a particular potential for thin-film based devices and nanomaterial engineering.
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Affiliation(s)
- Mehran Amiri
- Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, 16788-15811 Tehran, Iran; (M.A.); (M.F.)
| | - Javad Beheshtian
- Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, 16788-15811 Tehran, Iran; (M.A.); (M.F.)
- Correspondence: (J.B.); (F.S.)
| | - Farzaneh Shayeganfar
- Department of Physics and Energy Engineering, Amirkabir University of Technology, 15916-39675 Tehran, Iran
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA;
- Correspondence: (J.B.); (F.S.)
| | - Mahdi Faghihnasiri
- Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, 16788-15811 Tehran, Iran; (M.A.); (M.F.)
| | - Rouzbeh Shahsavari
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA;
| | - Ali Ramazani
- Department of Mechanical Engineering, MIT, Cambridge, MA 02139, USA;
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Shayeganfar F, Beheshtian J, Shahsavari R. Boron nitride nanochannels encapsulating a water/heavy water layer for energy applications. RSC Adv 2019; 9:5901-5907. [PMID: 35517256 PMCID: PMC9060902 DOI: 10.1039/c8ra09925a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/06/2019] [Indexed: 11/21/2022] Open
Abstract
Water interaction and transport through nanochannels of two-dimensional (2D) nanomaterials hold great promises in several applications including separation, energy harvesting and drug delivery. However, the fundamental underpinning of the electronic phenomena at the interface of such systems is poorly understood. Inspired by recent experiments, herein, we focus on water/heavy water in boron nitride (BN) nanochannels – as a model system – and report a series of ab initio based density functional theory (DFT) calculations on correlating the stability of adsorption and interfacial properties, decoding various synergies in the complex interfacial interactions of water encapsulated in BN nanocapillaries. We provide a comparison of phonon vibrational modes of water and heavy water (D2O) captured in bilayer BN (BLBN) to compare their mobility and group speed as a key factor for separation mechanisms. This finding, combined with the fundamental insights into the nature of the interfacial properties, provides key hypotheses for the design of nanochannels. Single layer water (SLW) on BN layer and encapsulated between bilayer BN (BLBN) as nanochannel.![]()
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Affiliation(s)
- Farzaneh Shayeganfar
- Department of Civil and Environmental Engineering
- Rice University
- Houston
- USA
- Department of Energy Engineering and Physics
| | - Javad Beheshtian
- Department of Chemistry
- Shahid Rajaee Teacher Training University
- Iran
| | - Rouzbeh Shahsavari
- Department of Civil and Environmental Engineering
- Rice University
- Houston
- USA
- Department of Material Science and NanoEngineering
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Abstract
Water confined to nanopores such as carbon nanotubes (CNTs) exhibits different states, enabling the study of solidlike water nanotubes (WNTs) and the potential application of their properties due to confined effects. Herein, we report the interfacial interaction and particular stabilized boundaries of confined WNTs within CNTs and boron nitride nanotubes (BNNTs) using first-principles calculations. We demonstrate that the intermolecular potential of nanotube walls exerts diameter-dependent additive or subtractive van der Waals (vdW) pressure on the WNTs, altering the phase boundaries. Our results reveal that the most stable WNT@CNT is associated with a CNT diameter of 10.5 Å. By correlating the stability of WNTs with interfacial properties such as the vdW pressure and vibrational phonon modes of confined WNTs, we decode and compare various synergies in water interaction and stabilized states within the CNTs and BNNTs, including interfacial properties of WNT@BNNTs that are more significant than those of WNT@CNTs. Our results suggest that the transition of a water tube to an ice tube is strongly dependent on the diameter of the confining CNT or BNNT, providing new insights on leveraging the interfacial interaction mechanism of confined WNTs and their potential application for fabricating nanochannels and nanocapacitors.
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Affiliation(s)
- Farzaneh Shayeganfar
- Department of Civil and Environmental Engineering , Rice University , Houston , Texas 77005 , United States
- Department of Energy Engineering and Physics , Amirkabir University , 14588 Tehran , Iran
| | - Javad Beheshtian
- Department of Chemistry , Shahid Rajaee Teacher Training University , 16875-163 Tehran , Iran
| | - Rouzbeh Shahsavari
- Department of Civil and Environmental Engineering , Rice University , Houston , Texas 77005 , United States
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Shayeganfar F, Beheshtiyan J, Neek-Amal M, Shahsavari R. Electro- and opto-mutable properties of MgO nanoclusters adsorbed on mono- and double-layer graphene. Nanoscale 2017; 9:4205-4218. [PMID: 28290570 DOI: 10.1039/c6nr08586e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Inspired by recent experiments, the trapping of molecules in 2D materials has gained increasing attention due to the unique ability of the molecules to modulate the electronic and optical properties of 2D materials, which calls for fundamental understanding and predictive design strategies. Herein, we focus on mono- and double-layer graphene encapsulating various MgO clusters and explore their diverse electronic and optical properties using a number of high-level first-principles calculations. By correlating the stability of adsorption, geometry, charge transfer, band structures, optical absorption spectrum, and the van der Waals pressure, our results decode various synergies in electro- and opto-mutable properties of MgO/graphene systems. We found that 2D-MgO flakes on graphene layers exhibit surface polarization effects - in contrast to their isolated neutral flakes - and show a significant charge transfer from graphene to n-doped flakes, breaking the symmetry of graphene layers. We obtained a van der Waals pressure of ∼0.7 (0.9) GPa on bilayer graphene encapsulating MgO nanoclusters, which matches extremely well with experiment. While there is one quantum emission in the visible light region for a single MgO flake, a wide range of visible light is accessible for MgO on mono- and double-layer graphene. Overall, these findings provide new physical insights and design strategies to modulate 2D materials with several applications in optoelectronics while significantly broadening the spectrum of strategies for fabricating new hybrid 2D heterostructures by encapsulating external molecules.
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Affiliation(s)
- Farzaneh Shayeganfar
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA. and Institute for Advanced Technologies, Shahid Rajaee Teacher Training University, 16875-163, Lavizan, Tehran, Iran
| | - Javad Beheshtiyan
- Institute for Advanced Technologies, Shahid Rajaee Teacher Training University, 16875-163, Lavizan, Tehran, Iran and Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Mehdi Neek-Amal
- Institute for Advanced Technologies, Shahid Rajaee Teacher Training University, 16875-163, Lavizan, Tehran, Iran and Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Rouzbeh Shahsavari
- Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA. and Department of Material Science and NanoEngineering, Rice University, Houston, TX 77005, USA and Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX 77005, USA
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Abstract
Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.
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Affiliation(s)
- Farzaneh Shayeganfar
- Institute for Advanced Technologies, Shahid Rajaee Teacher Training University , 16875-163 Lavizan, Tehran, Iran
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Hedayatifar L, Irani E, Mazarei M, Rasti S, Azar YT, Rezakhani AT, Mashaghi A, Shayeganfar F, Anvari M, Heydari T, Tabar AR, Nafari N, Vesaghi MA, Asgari R, Rahimi Tabar MR. Optical absorption and electronic spectra of chlorophylls a and b. RSC Adv 2016. [DOI: 10.1039/c6ra20226h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report optical and electronic properties of the two main chlorophylls in green plants, namely, chlorophylls a and b. We estimate the electric moments of these molecules and study absorption spectra of the chlorophylls.
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Shayeganfar F. Columnar organization of stack-assembled trimesic acid on graphene. J Phys Condens Matter 2014; 26:435305. [PMID: 25299971 DOI: 10.1088/0953-8984/26/43/435305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The stack-assembly of trimesic acid molecules into a highly organized columnar structure and their adsorption on graphene has been investigated by a DFT-based ab initio calculation method. Trimesic acid (TMA, benzene-1,3,5-tricarboxylic acid) constitutes an interesting building block for intermolecular hydrogen-bonding architecture by creating a strong net dipole moment which favors a symmetric π-stacking of molecular wire. Both the single orientation (syn) and alternating orientation (anti) of two- and three-unit TMA configurations are optimized, and determine that anti or AB pattern TMA wire is energetically more favorable than the syn case. Meanwhile, a decreasing band gap during the formation of the molecular wire proves the presence of delocalized π-electrons over the entire stack-assembly. The adsorption energy for a columnar TMA stack on graphene was found to be roughly less than of a single TMA adsorbed on graphene. The relative contribution of hydrogen bonding to column packing energy showed to be comparative and reasonable, with the energy of a conventional hydrogen bond. The magnitude of the band gap opening appears strongly correlated with the breaking of the symmetry of π-states of graphene by the TMA columnar patterning on the surface. Our results suggest that a stack-assembled molecular could be used to tune and control the electronic properties of graphene.
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Affiliation(s)
- F Shayeganfar
- Engineering Physics Department and Regroupement québécois sur les matériaux de pointe (RQMP), Polytechnique Montréal, Montréal, Québec H3C 3A7, Canada
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Abstract
The adsorption of trimesic acid (TMA) on a graphene surface has been studied with density functional theory. By considering the adsorption of a single TMA molecule on different sites on graphene, we have been able to perform a detailed analysis of the equilibrium geometry, charge transfer, electronic properties in terms of density of states and band structure, and finally scanning tunneling microscopy simulations on those simple systems. The results for isolated adsorption were then compared to the behavior of the TMA unit within two different self-assembled monolayers. Our results indicate that structural deformations of TMA may significantly contribute to the magnitude of p-doping and band gap opening in graphene. The formation of a hydrogen bonding network within the assembly improves the stability of the adlayer, but its adhesion on graphene is significantly reduced. The magnitude of p-doping in graphene per TMA unit remains nearly constant from the isolated to the assembled systems, but the magnitude of the band gap opening appears to be strongly correlated with the breaking of symmetry of π-states of graphene by the TMA patterning on the surface. Our results suggest that polymorphism in self-assembled adlayers could be used to tune and control the electronic properties of graphene.
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Affiliation(s)
- F Shayeganfar
- Engineering Physics Department and Regroupement québécois sur les matériaux de pointe (RQMP), Polytechnique Montréal , Montréal, Québec H3C 3A7, Canada
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Shayeganfar F, Eskandari Z, Rahimi Tabar MR, Sahimi M. Molecular dynamics simulation of formation and growth of CdS nanoparticles. Molecular Simulation 2013. [DOI: 10.1080/08927022.2013.811723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Shayeganfar F, Jabbari-Farouji S, Movahed MS, Jafari GR, Tabar MRR. Stochastic qualifier of gel and glass transitions in laponite suspensions. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:061404. [PMID: 20866418 DOI: 10.1103/physreve.81.061404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 04/27/2010] [Indexed: 05/29/2023]
Abstract
The existence of the important similarities between gelation and glass transition makes it hard to distinguish between the two types of nonergodic states experimentally. Here, we report on a stochastic analysis of the scattered light intensity through a colloidal particles suspension during the gel and glass formation. In this analysis, we exploit the methods developed for complex hierarchical systems, such as turbulence. Using the multiplicative log-normal cascade models, we provide a criterion to distinguish gels from glasses.
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Affiliation(s)
- F Shayeganfar
- Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran, Iran
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Shayeganfar F, Javidpour L, Taghavinia N, Rahimi Tabar MR, Sahimi M, Bagheri-Tar F. Controlled nucleation and growth of CdS nanoparticles by turbulent dispersion. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:026304. [PMID: 20365648 DOI: 10.1103/physreve.81.026304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2009] [Revised: 12/23/2009] [Indexed: 05/29/2023]
Abstract
We propose and test a method for controlling the size of nanoparticles, which plays a fundamental role in their electrical, optical, and mechanical properties. The method utilizes turbulent mixing, and is applicable to the fabrication of any type of nanoparticle that uses a solution environment in the preparation process. We show by well-controlled experiments on the CdS nanoparticles, which are semiconducting materials, that the average size d of the particles decreases with Reynolds number Re.
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Shayeganfar F, Jabbari-Farouji S, Movahed MS, Jafari GR, Tabar MRR. Multifractal analysis of light scattering-intensity fluctuations. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:061126. [PMID: 20365137 DOI: 10.1103/physreve.80.061126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Indexed: 05/29/2023]
Abstract
We provide a simple interpretation of non-Gaussian nature of the light scattering-intensity fluctuations from an aging colloidal suspension of Laponite using the multiplicative cascade model, Markovian method, and volatility correlations. The cascade model and Markovian method enable us to reproduce most of recent empirical findings: long-range volatility correlations and non-Gaussian statistics of intensity fluctuations. We provide evidence that the intensity increments Deltax(tau)=I(t+tau)-I(t), upon different delay time scales tau, can be described as a Markovian process evolving in tau. Thus, the tau dependence of the probability density function p(Deltax,tau) on the delay time scale tau can be described by a Fokker-Planck equation. We also demonstrate how drift and diffusion coefficients in the Fokker-Planck equation can be estimated directly from the data.
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Affiliation(s)
- F Shayeganfar
- Department of Physics, Sharif University of Technology, PO Box 11365-9161, Tehran, Iran
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