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Wang M, Liu G, Lei S, Wan N. Study on the growth mechanism of monolayer and few-layer hexagonal boron nitride films on copper foil. Phys Chem Chem Phys 2024; 26:18459-18465. [PMID: 38916111 DOI: 10.1039/d4cp01930j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
During the process of synthesizing h-BN on Cu foil via chemical vapor deposition (CVD), low-pressure CVD (LPCVD) typically synthesizes monolayer h-BN films, whereas atmospheric pressure CVD (APCVD) yields few-layer h-BN films. Herein, a growth mechanism for monolayer and few-layer h-BN on Cu foil is proposed using first-principles calculations: Cu(111) passivated h-BN hinders the diffusion of B and N atoms at the subsurface of Cu(111), preventing sufficient transportation of B and N atoms to the existing h-BN layer, thereby leading to the formation of monolayer h-BN in LPCVD. For APCVD, the edges of h-BN are passivated by H, which decreases the barrier energy for the diffusion of B and N atoms on the Cu(111) subsurface, and B and N atoms can easily migrate from the subsurface of Cu(111) to its surface, resulting in the nucleation of h-BN between the existing h-BN and Cu(111), and leading to the formation of few-layer h-BN films. This work provides a theoretical basis at the atomic scale for further understanding the growth of monolayer and few-layer h-BN films on Cu foil.
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Affiliation(s)
- Mingyuan Wang
- Key Laboratory of MEMS of Ministry of Education, School of Integrated Circuits, Southeast University, Nanjing, 210096, China.
| | - Guiwu Liu
- School of Materials Science and Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Shuangying Lei
- Key Laboratory of MEMS of Ministry of Education, School of Integrated Circuits, Southeast University, Nanjing, 210096, China.
| | - Neng Wan
- Key Laboratory of MEMS of Ministry of Education, School of Integrated Circuits, Southeast University, Nanjing, 210096, China.
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2
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Santos EAJ, Lima KAL, Mendonça FLL, Silva DAD, Giozza WF, Junior LAR. PHOTH-graphene: a new 2D carbon allotrope with low barriers for Li-ion mobility. Sci Rep 2024; 14:9526. [PMID: 38664467 PMCID: PMC11045837 DOI: 10.1038/s41598-024-59858-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
The continued interest in 2D carbon allotropes stems from their unique structural and electronic characteristics, which are crucial for diverse applications. This work theoretically introduces PHOTH-Graphene (PHOTH-G), a novel 2D planar carbon allotrope formed by 4-5-6-7-8 carbon rings. PHOTH-G emerges as a narrow band gap semiconducting material with low formation energy, demonstrating good stability under thermal and mechanical conditions. This material has slight mechanical anisotropy with Young modulus and Poisson ratios varying between 7.08-167.8 GPa and 0.21-0.96. PHOTH-G presents optical activity restricted to the visible range. Li atoms adsorbed on its surface have a migration barrier averaging 0.38 eV.
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Affiliation(s)
- E A J Santos
- Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil
| | - K A L Lima
- Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil
| | - F L L Mendonça
- Department of Electrical Engineering, Faculty of Technology, University of Brasília, Brasília, Brazil
| | - D A da Silva
- Professional Postgraduate Program in Electrical Engineering - PPEE, University of Brasília, Brasília, Brazil
| | - W F Giozza
- Department of Electrical Engineering, Faculty of Technology, University of Brasília, Brasília, Brazil
| | - L A Ribeiro Junior
- Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil.
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil.
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Santos EAJ, Lima KAL, Ribeiro Junior LA. Proposing TODD-graphene as a novel porous 2D carbon allotrope designed for superior lithium-ion battery efficiency. Sci Rep 2024; 14:6202. [PMID: 38485984 PMCID: PMC10940596 DOI: 10.1038/s41598-024-56312-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/05/2024] [Indexed: 03/18/2024] Open
Abstract
The category of 2D carbon allotropes has gained considerable interest due to its outstanding optoelectronic and mechanical characteristics, which are crucial for various device applications, including energy storage. This study uses density functional theory calculations, ab initio molecular dynamics (AIMD), and classical reactive molecular dynamics (MD) simulations to introduce TODD-Graphene, an innovative 2D planar carbon allotrope with a distinctive porous arrangement comprising 3-8-10-12 carbon rings. TODD-G exhibits intrinsic metallic properties with a low formation energy and stability in thermal and mechanical behavior. Calculations indicate a substantial theoretical capacity for adsorbing Li atoms, revealing a low average diffusion barrier of 0.83 eV. The metallic framework boasts excellent conductivity and positioning TODD-G as an active layer for superior lithium-ion battery efficiency. Charge carrier mobility calculations for electrons and holes in TODD-G surpass those of graphene. Classical reactive MD simulation results affirm its structural integrity, maintaining stability without bond reconstructions at 2200 K.
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Affiliation(s)
- E A J Santos
- Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil
| | - K A L Lima
- Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil
| | - L A Ribeiro Junior
- Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil.
- Computational Materials Laboratory, LCCMat, Institute of Physics, University of Brasília, Brasília, 70910-900, Brazil.
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4
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Park BI, Kim J, Lu K, Zhang X, Lee S, Suh JM, Kim DH, Kim H, Kim J. Remote Epitaxy: Fundamentals, Challenges, and Opportunities. NANO LETTERS 2024; 24:2939-2952. [PMID: 38477054 DOI: 10.1021/acs.nanolett.3c04465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
Advanced heterogeneous integration technologies are pivotal for next-generation electronics. Single-crystalline materials are one of the key building blocks for heterogeneous integration, although it is challenging to produce and integrate these materials. Remote epitaxy is recently introduced as a solution for growing single-crystalline thin films that can be exfoliated from host wafers and then transferred onto foreign platforms. This technology has quickly gained attention, as it can be applied to a wide variety of materials and can realize new functionalities and novel application platforms. Nevertheless, remote epitaxy is a delicate process, and thus, successful execution of remote epitaxy is often challenging. Here, we elucidate the mechanisms of remote epitaxy, summarize recent breakthroughs, and discuss the challenges and solutions in the remote epitaxy of various material systems. We also provide a vision for the future of remote epitaxy for studying fundamental materials science, as well as for functional applications.
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Affiliation(s)
- Bo-In Park
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jekyung Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kuangye Lu
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Xinyuan Zhang
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sangho Lee
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jun Min Suh
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Dong-Hwan Kim
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Hyunseok Kim
- Department of Electrical and Computer Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Nick Holonyak, Jr. Micro and Nanotechnology Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Jeehwan Kim
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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5
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Vaezi M, Nejat Pishkenari H. Toward steering the motion of surface rolling molecular machines by straining graphene substrate. Sci Rep 2023; 13:20816. [PMID: 38012233 PMCID: PMC10682032 DOI: 10.1038/s41598-023-48214-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 11/23/2023] [Indexed: 11/29/2023] Open
Abstract
The surface rolling molecular machines are proposed to perform tasks and carrying molecular payloads on the substrates. As a result, controlling the surface motion of these molecular machines is of interest for the design of nano-transportation systems. In this study, we evaluate the motion of the nanocar on the graphene nanoribbons with strain gradient, through the molecular dynamics (MD) simulations, and theoretical relations. The nanocar indicates directed motion from the maximum strained part of the graphene to the unstrained end of the substrate. The strain gradient induced driving force and diffusion coefficients of nanocars are analyzed from the simulation and theoretical points of view. To obtain the optimum directed motion of nanocar, we consider the effects of temperature, strain average, and magnitude of strain gradient on the directionality of the motion. Moreover, the mechanism of the motion of nanocar is studied by evaluating the direction of the nanocar's chassis and the rotation of wheels around the axles. Ultimately, the programmable motion of nanocar is shown by adjusting the strain gradient of graphene substrate.
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Affiliation(s)
- Mehran Vaezi
- Center for Nanoscience and Nanotechnology, Institute for Convergence Science & Technology , Sharif University of Technology, Tehran, Iran
| | - Hossein Nejat Pishkenari
- Nano Robotics Laboratory, Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran.
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6
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Hammud HH, Yar M, Bayach I, Ayub K. Covalent Triazine Framework C 6N 6 as an Electrochemical Sensor for Hydrogen-Containing Industrial Pollutants. A DFT Study. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1121. [PMID: 36986015 PMCID: PMC10053058 DOI: 10.3390/nano13061121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/07/2023] [Accepted: 03/15/2023] [Indexed: 06/18/2023]
Abstract
Industrial pollutants pose a serious threat to ecosystems. Hence, there is a need to search for new efficient sensor materials for the detection of pollutants. In the current study, we explored the electrochemical sensing potential of a C6N6 sheet for H-containing industrial pollutants (HCN, H2S, NH3 and PH3) through DFT simulations. The adsorption of industrial pollutants over C6N6 occurs through physisorption, with adsorption energies ranging from -9.36 kcal/mol to -16.46 kcal/mol. The non-covalent interactions of analyte@C6N6 complexes are quantified by symmetry adapted perturbation theory (SAPT0), quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analyses. SAPT0 analyses show that electrostatic and dispersion forces play a dominant role in the stabilization of analytes over C6N6 sheets. Similarly, NCI and QTAIM analyses also verified the results of SAPT0 and interaction energy analyses. The electronic properties of analyte@C6N6 complexes are investigated by electron density difference (EDD), natural bond orbital analyses (NBO) and frontier molecular orbital analyses (FMO). Charge is transferred from the C6N6 sheet to HCN, H2S, NH3 and PH3. The highest exchange of charge is noted for H2S (-0.026 e-). The results of FMO analyses show that the interaction of all analytes results in changes in the EH-L gap of the C6N6 sheet. However, the highest decrease in the EH-L gap (2.58 eV) is observed for the NH3@C6N6 complex among all studied analyte@C6N6 complexes. The orbital density pattern shows that the HOMO density is completely concentrated on NH3, while the LUMO density is centred on the C6N6 surface. Such a type of electronic transition results in a significant change in the EH-L gap. Thus, it is concluded that C6N6 is highly selective towards NH3 compared to the other studied analytes.
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Affiliation(s)
- Hassan H. Hammud
- Department of Chemistry, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Muhammad Yar
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, KPK, Islamabad 22060, Pakistan
| | - Imene Bayach
- Department of Chemistry, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Khurshid Ayub
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, KPK, Islamabad 22060, Pakistan
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7
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Sangiovanni DG, Faccio R, Gueorguiev GK, Kakanakova-Georgieva A. Discovering atomistic pathways for supply of metal atoms from methyl-based precursors to graphene surface. Phys Chem Chem Phys 2022; 25:829-837. [PMID: 36511446 DOI: 10.1039/d2cp04091c] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Conceptual 2D group III nitrides and oxides (e.g., 2D InN and 2D InO) in heterostructures with graphene have been realized by metal-organic chemical vapor deposition (MOCVD). MOCVD is expected to bring forth the same impact in the advancement of 2D semiconductor materials as in the fabrication of established semiconductor materials and device heterostructures. MOCVD employs metal-organic precursors such as trimethyl-indium, -gallium, and -aluminum, with (strong) metal-carbon bonds. Mechanisms that regulate MOCVD processes at the atomic scale are largely unknown. Here, we employ density-functional molecular dynamics - accounting for van der Waals interactions - to identify the reaction pathways responsible for dissociation of the trimethylindium (TMIn) precursor in the gas phase as well as on top-layer and zero-layer graphene. The simulations reveal how collisions with hydrogen molecules, intramolecular or surface-mediated proton transfer, and direct TMIn/graphene reactions assist TMIn transformations, which ultimately enables delivery of In monomers or InH and CH3In admolecules, on graphene. This work provides knowledge for understanding the nucleation and intercalation mechanisms at the atomic scale and for carrying out epitaxial growth of 2D materials and graphene heterostructures.
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Affiliation(s)
- Davide G Sangiovanni
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83, Linköping, Sweden.
| | - Ricardo Faccio
- Área Física & Centro Nanomat, DETEMA, Facultad de Química, Universidad de la República, Av. Gral. Flores 2124, C.P., 11800, Montevideo, Uruguay
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8
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Liu J, He X. Recent advances in quantum fragmentation approaches to complex molecular and condensed‐phase systems. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jinfeng Liu
- Department of Basic Medicine and Clinical Pharmacy China Pharmaceutical University Nanjing China
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering East China Normal University Shanghai China
| | - Xiao He
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering East China Normal University Shanghai China
- New York University‐East China Normal University Center for Computational Chemistry New York University Shanghai Shanghai China
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9
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Park S, Han H, Kim H, Choi S. Machine Learning Applications for Chemical Reactions. Chem Asian J 2022; 17:e202200203. [PMID: 35471772 PMCID: PMC9401034 DOI: 10.1002/asia.202200203] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/26/2022] [Indexed: 11/30/2022]
Abstract
Machine learning (ML) approaches have enabled rapid and efficient molecular property predictions as well as the design of new novel materials. In addition to great success for molecular problems, ML techniques are applied to various chemical reaction problems that require huge costs to solve with the existing experimental and simulation methods. In this review, starting with basic representations of chemical reactions, we summarized recent achievements of ML studies on two different problems; predicting reaction properties and synthetic routes. The various ML models are used to predict physical properties related to chemical reaction properties (e. g. thermodynamic changes, activation barriers, and reaction rates). Furthermore, the predictions of reactivity, self-optimization of reaction, and designing retrosynthetic reaction paths are also tackled by ML approaches. Herein we illustrate various ML strategies utilized in the various context of chemical reaction studies.
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Affiliation(s)
- Sanggil Park
- Department of ChemistryIncheon Natoinal University and Research Institute of Basic SciencesIncheon22012Republic of Korea
| | - Herim Han
- Digital Bio R&D CenterMediazenSeoul07789Republic of Korea
- Department of Polymer Science and EngineeringDankook UniversityYongin, Gyeonggi16890Republic of Korea
| | - Hyungjun Kim
- Department of ChemistryIncheon Natoinal University and Research Institute of Basic SciencesIncheon22012Republic of Korea
| | - Sunghwan Choi
- Division of National SupercomputingKorea Institute of Science and Technology InformationDaejeon34141Republic of Korea
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Vaezi M, Nejat Pishkenari H, Ejtehadi MR. Collective movement and thermal stability of fullerene clusters on the graphene layer. Phys Chem Chem Phys 2022; 24:11770-11781. [PMID: 35506871 DOI: 10.1039/d2cp00667g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Understanding the motion characteristics of fullerene clusters on the graphene surface is critical for designing surface manipulation systems. Toward this purpose, using the molecular dynamics method, we evaluated six clusters of fullerenes including 1, 2, 3, 5, 10, and 25 molecules on the graphene surface, in the temperature range of 25 to 500 K. First, the surface motion of clusters is studied at 200 K and lower temperatures, in which fullerenes remain as a single group. The trajectories of the motion as well as the diffusion coefficients indicate the reduction of surface mobility as a response to the increase of the fullerene number. The clusters show normal diffusion at the temperature of 25 K, while they follow the super-diffusion regime at higher temperatures. The separation of fullerenes occurs at 300 K and higher temperatures. Due to the increase of vdW attraction with the increase of the fullerene number, the separation of fullerenes in larger clusters occurs at higher temperatures. The thermal energy at 500 K is sufficient to divide the large C60 clusters into smaller clusters. This energy level is related to the saturation of the interaction energy experienced by individual fullerenes, which can be estimated from the potential energy analysis. The results of simulations reveal that the separation occurs at the edge of clusters. Moreover, we studied the thermal stability of multilayer fullerene clusters on graphene. The simulation results indicate the tendency of multilayer clusters to locate on the surface, which implies the wetting property of C60s on the graphene layer.
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Affiliation(s)
- Mehran Vaezi
- Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Tehran, Iran
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11
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Fan QY, Liu JL, Gong FQ, Wang Y, Cheng J. Structural dynamics of Ru clusters during nitrogen dissociation in ammonia synthesis. Phys Chem Chem Phys 2022; 24:10820-10825. [PMID: 35482304 DOI: 10.1039/d2cp00678b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamic evolution of catalyst structures greatly influences the reactivity, especially sub-nanometer clusters, exhibiting complex configurational fluctuation. In the present work, we study the structural dynamics of a Ru19 cluster during the dissociation of N2 and calculate the reaction free energies using ab initio molecular dynamics (AIMD). Our AIMD calculation predicts a peak-shaped reaction entropy curve due to the adsorption-induced phase transition of the Ru19 cluster. The low melting points of sub-nanometer clusters make it possible to activate N2 at low temperatures. This work demonstrates that the dynamic changes of cluster structures have a non-negligible effect on reaction free energy and offer an opportunity for achieving ammonia synthesis under mild conditions.
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Affiliation(s)
- Qi-Yuan Fan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Jing-Li Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Fu-Qiang Gong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Ye Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Jun Cheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
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12
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Xia J, Cao R, Wu Q. Transition metal decorated phthalocyanine as a potential host material for lithium polysulfides: a first-principles study. RSC Adv 2022; 12:13975-13984. [PMID: 35558832 PMCID: PMC9093166 DOI: 10.1039/d2ra02049a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/29/2022] [Indexed: 11/21/2022] Open
Abstract
The shuttle effect caused by the soluble long-chain lithium polysulfides greatly hinders the practical application of lithium–sulfur (Li–S) batteries. Therefore, the introduction of suitable anchoring materials is more effective to mitigate this problem. Transition metal phthalocyanines (TMPc) are regarded as a new class of sulfur host materials. Here, 4d transition metal (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) decorated phthalocyanines are designed and systematically researched for the performance analysis of anchoring S8/LiPSs by first-principles calculations. The results reveal that the bonding strength of LiPSs can be well adjusted by introducing suitable 4d transition metals into the phthalocyanine structure. The electronic structure analysis indicates the formation of TM–S bonds between the TMPc substrate materials and the LiPSs, which is essential to weaken the Li–S bonds and hence slow down the shuttle effect of LiPSs. ZrPc and NbPc both exhibit excellent potential and thermal stability for facilitating the conversion of LiPSs, as well as a better promoting effect for the sulfur reduction reactions (SRR) with a reduced Gibbs free energy in the rate-determining step (*Li2S2 → *Li2S) during the discharge reaction process. These findings in our work may encourage further experimental and theoretical research for anchoring LiPSs with TMPc as a host material. DFT calculations reveal that TMPc, especially ZrPc and NbPc exhibit the best anchoring and catalytic effects for lithium polysulfides.![]()
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Affiliation(s)
- Jiezhen Xia
- Department of Physics, School of Science, Tibet University Lhasa 850000 China.,Institute of Oxygen Supply, Center of Tibetan Studies (Everest Research Institute), Tibet University Lhasa 850000 China
| | - Rong Cao
- Department of Physics, School of Science, Tibet University Lhasa 850000 China.,Institute of Oxygen Supply, Center of Tibetan Studies (Everest Research Institute), Tibet University Lhasa 850000 China
| | - Qi Wu
- Department of Physics, School of Science, Tibet University Lhasa 850000 China.,Institute of Oxygen Supply, Center of Tibetan Studies (Everest Research Institute), Tibet University Lhasa 850000 China.,Key Laboratory of Cosmic Rays (Tibet University), Ministry of Education Lhasa 850000 China
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13
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Meng H, Han B, Li F, Zhao J, Chen Z. Understanding the CH4 Conversion over Metal Dimers from First Principles. NANOMATERIALS 2022; 12:nano12091518. [PMID: 35564225 PMCID: PMC9100024 DOI: 10.3390/nano12091518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 11/20/2022]
Abstract
Inspired by the advantages of bi-atom catalysts and recent exciting progresses of nanozymes, by means of density functional theory (DFT) computations, we explored the potential of metal dimers embedded in phthalocyanine monolayers (M2-Pc), which mimics the binuclear centers of methane monooxygenase, as catalysts for methane conversion using H2O2 as an oxidant. In total, 26 transition metal (from group IB to VIIIB) and four main group metal (M = Al, Ga, Sn and Bi) dimers were considered, and two methane conversion routes, namely *O-assisted and *OH-assisted mechanisms were systematically studied. The results show that methane conversion proceeds via an *OH-assisted mechanism on the Ti2-Pc, Zr2-Pc and Ta2-Pc, a combination of *O- and *OH-assisted mechanism on the surface of Sc2-Pc, respectively. Our theoretical work may provide impetus to developing new catalysts for methane conversion and help stimulate further studies on metal dimer catalysts for other catalytic reactions.
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Affiliation(s)
- Haihong Meng
- School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China; (H.M.); (B.H.)
| | - Bing Han
- School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China; (H.M.); (B.H.)
| | - Fengyu Li
- School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China; (H.M.); (B.H.)
- Correspondence: (F.L.); (J.Z.); (Z.C.)
| | - Jingxiang Zhao
- Key Laboratory of Photonic and Electronic Bandgap Materials, College of Chemistry and Chemical Engineering, Ministry of Education, Harbin Normal University, Harbin 150025, China
- Correspondence: (F.L.); (J.Z.); (Z.C.)
| | - Zhongfang Chen
- Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931, USA
- Correspondence: (F.L.); (J.Z.); (Z.C.)
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14
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Ito K, Matsumoto M. Adsorption Free Energy of Cellulose Nanocrystal on Water–Oil Interface. NANOMATERIALS 2022; 12:nano12081321. [PMID: 35458030 PMCID: PMC9029831 DOI: 10.3390/nano12081321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 12/10/2022]
Abstract
To investigate the amphiphilicity of cellulose, a series of molecular dynamics simulations were performed with a cellulose nanocrystal and a water–octane interfacial system. Assuming that the axis of cellulose is parallel to the water–octane interface, the freedoms of motion of the nanocrystal were restricted to two, the distance from the interface and the orientation around the axis. The mean force and the mean torque on the nanocrystal were evaluated with sufficiently long simulation at each crystal configuration, and their numerical integration gave a smooth free energy surface as the potential of mean force. The cellulose sample used here was found to be much more hydrophilic than oleophilic with the free energy difference ΔFw→o=318 kcal/mol. Three adsorption states with local minimum of adsorption free energy are distinguished in the free energy surface—the direct contact type which is similar to previously reported one, the hydrophilic-surface/water/octane type where a thin water layer is sandwiched between the surface and the octane phase, and the oleophilic/water/octane type where a thin water layer also exists. Water molecules in these water layers contribute to stabilize the adsorption states by taking a special orientational order and slow self-diffusion.
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15
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Hirai H, Jinnouchi R. Discovering surface reaction pathways using accelerated molecular dynamics and network analysis tools. RSC Adv 2022; 12:23274-23283. [PMID: 36090391 PMCID: PMC9382359 DOI: 10.1039/d2ra04343b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/10/2022] [Indexed: 11/21/2022] Open
Abstract
We present an automated method that maps surface reaction pathways with no experimental data and with minimal human interventions. In this method, bias potentials promoting surface reactions are applied to enable statistical samplings of the surface reaction within the timescale of ab initio molecular dynamics (MD) simulations, and elementary reactions are extracted automatically using an extension of the method constructed for gas- or liquid-phase reactions. By converting the extracted elementary reaction data to directed graph data, MD trajectories can be efficiently mapped onto reaction pathways using a network analysis tool. To demonstrate the power of the method, it was applied to the steam reforming of methane on the Rh(111) surface and to propane reforming on the Pt(111) and Pt3Sn(111) surfaces. We discover new energetically favorable pathways for both reactions and reproduce the experimentally-observed materials-dependence of the surface reaction activity and the selectivity for the propane reforming reactions. We present an automated method that maps surface reaction pathways with no experimental data and with minimal human interventions.![]()
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Affiliation(s)
- Hirotoshi Hirai
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Ryosuke Jinnouchi
- Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan
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16
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Chapleski RC, Chowdhury AU, Mason KR, Sacci RL, Doughty B, Roy S. Interfacial acidity on the strontium titanate surface: a scaling paradigm and the role of the hydrogen bond. Phys Chem Chem Phys 2021; 23:23478-23485. [PMID: 34569563 DOI: 10.1039/d1cp03587h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A fundamental understanding of acidity at an interface, as mediated by structure and molecule-surface interactions, is essential to elucidate the mechanisms of a range of chemical transformations. While the strength of an acid in homogeneous gas and solution phases is conceptually well understood, acid-base chemistry at heterogeneous interfaces is notoriously more complicated. Using density functional theory and nonlinear vibrational spectroscopy, we present a method to determine the interfacial Brønsted-Lowry acidity of aliphatic alcohols adsorbed on the (100) surface of the model perovskite, strontium titanate. While shorter and less branched alkanols are known to be less acidic in the gas phase and more acidic in solution, here we show that shorter alcohols are less acidic whereas less substituted alkanols are more acidic at the gas-oxide interface. Hydrogen bonding plays a critical role in defining acidity, whereas structure-acidity relationships are dominated by van der Waals interactions between the alcohol and the surface.
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Affiliation(s)
- Robert C Chapleski
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA. .,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Azhad U Chowdhury
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Kyle R Mason
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
| | - Robert L Sacci
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Sharani Roy
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
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17
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Randrianandraina J, Badawi M, Cardey B, Grivet M, Groetz JE, Ramseyer C, Anzola FT, Chambelland C, Ducret D. Adsorption of water in Na-LTA zeolites: an ab initio molecular dynamics investigation. Phys Chem Chem Phys 2021; 23:19032-19042. [PMID: 34612441 DOI: 10.1039/d1cp02624k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The very wide range of applications of LTA zeolites, including the storage of tritiated water, implies that a detailed and accurate atomic-scale description of the adsorption processes taking place in their structure is crucial. To unravel with an unprecedented accuracy the mechanisms behind the water filling in NaA, we have conducted a systematic ab initio molecular dynamics investigation. Two LTA structural models, the conventional Z4A and the reduced one ZK4, have been used for static and dynamic ab initio calculations, respectively. After assessing this reduced model with comparative static DFT calculations, we start the filling of the α and β cages by water, molecule by molecule. This allowed us to thoroughly study the interaction of water molecules with the zeolite structure and between water molecules, progressively forming H-bond chains and ring patterns as the cage is being filled. The adsorption energies could then be calculated with an unprecedented accuracy, which showed that the interaction of the molecules with the zeolite weakens as their number increases. By these methods, we have been able to highlight the primary role of Na+ cations in the interaction of water with zeolite, and inversely, the role of water in the displacement of cations when it is sufficiently solvated, allowing the passage between the α and β cages. This phenomenon is possible thanks to the inhomogeneous distribution of water molecules on the cationic sites, as shown by our AIMD simulations, which allows the formation of water clusters. These results are important because they help in understanding how the coverage of cationic sites by water will affect the adsorption of other molecules inside the Na-LTA zeolite.
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Affiliation(s)
- Joharimanitra Randrianandraina
- Laboratoire Chrono-Environnement UMR 6249, Université de Bourgogne Franche-Comté, 16 route de Gray, F-25030 Besançon Cedex, France.
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18
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Farigliano LM, Paredes-Olivera PA, Patrito EM. Oxidative etching of S-vacancy defective MoS 2 monolayer upon reaction with O 2. Phys Chem Chem Phys 2021; 23:10225-10235. [PMID: 33881024 DOI: 10.1039/d0cp06502a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The reactions of O2 with S vacancy sites within a MoS2 monolayer were investigated using density functional theory calculations. We considered the following defects: single S vacancy, double S vacancy, two adjacent S vacancies and two S vacancies separated by a sulphur atom. We found that the surface distribution of S vacancy sites plays a key role in determining the surface reactivity towards O2. We observed the desorption of SO2 only for the last vacancy distribution. For the other cases, the surface becomes passivated with very stable structures having O atoms on the original vacancy sites and in some cases an SO group in an adjacent position. The ab initio molecular dynamics simulations showed that the impingement of the O2 molecule on an S vacancy site produces a stable chemisorbed O2 molecule with an upright configuration. The surface reactions initiate after the O2 molecule switches to the lying-down configuration which favours the breakage of the O-O bond and the concurrent formation of S-O bonds. In the most reactive vacancy site configuration, the dissociation of the first O2 molecule produces an SO intermediate which finally leads to desorption of SO2 after oxygen abstraction from the other adjacent O2 molecule. The formation of a MoO3 moiety within the monolayer was also observed in the molecular dynamic simulations at higher oxidation levels.
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Affiliation(s)
- Lucas M Farigliano
- Departamento de Fisicoquímica, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina.
| | - Patricia A Paredes-Olivera
- Departamento de Química Teórica y Computacional, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
| | - Eduardo M Patrito
- Departamento de Fisicoquímica, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina.
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19
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Hirai H, Jinnouchi R. Discovering chemical reaction pathways using accelerated molecular dynamics simulations and network analysis tools – Application to oxidation induced decomposition of ethylene carbonate. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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20
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Yu Y, Zhou Z, Xu L, Ding Y, Fang G. Reaction mechanism of atomic layer deposition of aluminum sulfide using trimethylaluminum and hydrogen sulfide. Phys Chem Chem Phys 2021; 23:9594-9603. [PMID: 33885104 DOI: 10.1039/d1cp00864a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Atomic layer deposition (ALD) is a nanopreparation technique for materials and is widely used in the fields of microelectronics, energy and catalysis. ALD methods for metal sulfides, such as Al2S3 and Li2S, have been developed for lithium-ion batteries and solid-state electrolytes. In this work, using density functional theory calculations, the possible reaction pathways of the ALD of Al2S3 using trimethylaluminum (TMA) and H2S were investigated at the M06-2X/6-311G(d, p) level. Al2S3 ALD can be divided into two consecutive and complementary half-reactions involving TMA and H2S, respectively. In the TMA half-reaction, the methyl group can be eliminated through the reaction with the sulfhydryl group on the surface. This process is a ligand exchange reaction between the methyl and sulfhydryl groups via a four-membered ring transition state. TMA half-reaction with the sulfhydrylated surface is more difficult than that with the hydroxylated surface. When the temperature increases, the reaction requires more energy, owing to the contribution of the entropy. In the H2S half-reaction, the methyl group on the surface can further react with the H2S precursor via a four-membered ring transition state. The orientation of H2S and more molecules have minimal effect on the H2S half-reaction. The reaction involving H2S through a six-membered ring transition state is unfavorable. In addition, the methyl and sulfhydryl groups on the surface can both react with the adjacent sulfhydryl group on the subsurface to form and release CH4 or H2S in the two half-reactions. Furthermore, sulfhydryl elimination occurs more easily than methyl elimination on the surface. These findings for the TMA and H2S half-reactions of Al2S3 ALD may be used for studying precursor chemistry and improvements in the preparation of other metal sulfides for emerging applications.
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Affiliation(s)
- Yanghong Yu
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
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21
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Hybrid Nanostructures Obtained by Transport and Condensation of Tungsten Oxide Vapours onto CNW Templates. NANOMATERIALS 2021; 11:nano11040835. [PMID: 33805134 PMCID: PMC8064063 DOI: 10.3390/nano11040835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 11/17/2022]
Abstract
We present hybrid nanomaterial architectures, consisting of carbon nanowalls (CNW) templates decorated with tungsten oxide nanoparticles, synthesized using a mechanism based on tungsten oxide sublimation, vapor transport, followed by vapor condensation, in the absence or presence of plasma. The key steps in the decoration mechanism are the sublimation of tungsten oxides, when are exposed in vacuum at high temperature (800 °C), and their redeposition on colder surfaces (400-600 °C). The morphology and chemical composition of the hybrid architectures, as obtained from Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy, are discussed with respect to substrate nature and the physical conditions of synthesis. We pointed out that the decoration process is strongly dependent on the temperature of the CNW templates and plasma presence. Thus, the decoration process performed with plasma was effective for a wider range of template temperatures, in contrast with the decoration process performed without plasma. The results are useful for applications using the sensing and photochemical properties of tungsten oxides, and have also relevance for fusion technology, tungsten walls erosion and material redeposition being widely observed in fusion machines.
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22
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Rahman MH, Chowdhury EH, Redwan DA, Mitra S, Hong S. Characterization of the mechanical properties of van der Waals heterostructures of stanene adsorbed on graphene, hexagonal boron-nitride and silicon carbide. Phys Chem Chem Phys 2021; 23:5244-5253. [PMID: 33629670 DOI: 10.1039/d0cp06426b] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stanene has revealed a new horizon in the field of quantum condensed matter and energy conversion devices but its significantly lower tensile strength limits its further applications and effective operation in these nanodevices. Van der Waals heterostructures have given substantial flexibility to integrate different two-dimensional (2D) layered materials over the past few years and have proven highly functional with exceptional features, appealing applications, and innovative physics. Considerable efforts have been made for the preparation, thorough understanding, and applications of van der Waals heterostructures in the fields of electronics and optoelectronics. In this paper, we have executed Molecular Dynamics (MD) simulations to predict the tensile strength of van der Waals heterostructures of stanene (Sn) adsorbed on graphene (Gr), hexagonal boron nitride (hBN), and silicon carbide (SiC) (Sn/Gr, Sn/hBN, and Sn/SiC, respectively) subjected to both armchair and zigzag directional loading at different strain rates for the first time, which has enticing applications in electronic, optoelectronic, energy storage and bio-engineered devices. Among all the van der Waals heterostructures, the Sn/SiC heterostructure exhibits the lowest tensile strength and tensile strain. Furthermore, it has been found that zigzag directional loading could endure more tensile strain before fracture. Besides, it has been disclosed that though the rule of mixtures may accurately reproduce the Young's modulus of these heterostructures, it has limitations to predict the tensile strength. Fracture analysis suggests that for the Sn/hBN heterostructure the fracture initiates from the stanene layer while for the Sn/Gr and Sn/SiC heterostructures the fracture initiates from the Gr and SiC layer, respectively, for both armchair and zigzag directional loading. Overall, this study would aid in the design and efficient operation of Sn/Gr, Sn/hBN, and Sn/SiC heterostructures when subjected to mechanical force.
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Affiliation(s)
- Md Habibur Rahman
- Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh
| | - Emdadul Haque Chowdhury
- Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh
| | - Didarul Ahasan Redwan
- Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh
| | - Shailee Mitra
- Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh
| | - Sungwook Hong
- Department of Physics and Engineering, California State University, Bakersfield, Bakersfield, 93311, USA.
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23
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Tatrari G, Tewari C, Karakoti M, Pathak M, Jangra R, Santhibhushan B, Mahendia S, Sahoo NG. Mass production of metal-doped graphene from the agriculture waste of Quercus ilex leaves for supercapacitors: inclusive DFT study. RSC Adv 2021; 11:10891-10901. [PMID: 35423565 PMCID: PMC8695820 DOI: 10.1039/d0ra09393a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/28/2021] [Indexed: 11/21/2022] Open
Abstract
This work reports a facile, eco-friendly, and cost-effective mass-scale synthesis of metal-doped graphene sheets (MDGs) using agriculture waste of Quercus ilex leaves for supercapacitor applications. A single step-degradation catalyst-based pyrolysis route was used for the manufacture of MDGs. Obtained MDGs were further evaluated via advanced spectroscopy and microscopic techniques including Raman spectroscopy, FT-IR, XRD, SEM/EDX, and TEM imaging. The Raman spectrum showed D and G bands at 1300 cm-1 and 1590 cm-1, respectively, followed by a 2D band at 2770 cm-1, which confirmed the synthesis of few-layered MDGs. The SEM/EDX data confirmed the presence of 6.15%, 3.17%, and 2.36% of potassium, calcium and magnesium in the obtained MDGs, respectively. Additionally, the FT-IR, XRD, TEM, and SEM data including the plot profile diagrams confirmed the synthesis of MDGs. Further, a computational study was performed for the structural validation of MDGs using Gaussian 09. The density functional theory (DFT) results showed a chemisorption/decoration pattern of doping for metal ions on the few-layered graphene nanosheets, rather than a substitutional pattern. Further, resulting MDGs were used as an active material for the fabrication of a supercapacitor electrode using the polymer gel of PVA-H3PO4 as the electrolyte. The fabricated device showed a decent specific capacitance of 18.2 F g-1 at a scan rate of 5 mV s-1 with a power density of 1000 W kg-1 at 5 A g-1.
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Affiliation(s)
- Gaurav Tatrari
- PRS-NSNT Centre, Department of Chemistry, D.S.B. Campus, Kumaun University Nainital 263001 Uttarakhand India
| | - Chetna Tewari
- PRS-NSNT Centre, Department of Chemistry, D.S.B. Campus, Kumaun University Nainital 263001 Uttarakhand India
| | - Manoj Karakoti
- PRS-NSNT Centre, Department of Chemistry, D.S.B. Campus, Kumaun University Nainital 263001 Uttarakhand India
| | - Mayank Pathak
- PRS-NSNT Centre, Department of Chemistry, D.S.B. Campus, Kumaun University Nainital 263001 Uttarakhand India
| | - Ritu Jangra
- Department of Physics, Kurukshetra University Kurukshetra India
| | - Boddepalli Santhibhushan
- Department of Electrical Engineering, Indian Institute of Technology Bombay 400076 Maharashtra India
| | - Suman Mahendia
- Department of Physics, Kurukshetra University Kurukshetra India
| | - Nanda Gopal Sahoo
- PRS-NSNT Centre, Department of Chemistry, D.S.B. Campus, Kumaun University Nainital 263001 Uttarakhand India
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An In-Depth Assessment of the Electronic and Magnetic Properties of a Highly Ordered Hybrid Interface: The Case of Nickel Tetra-Phenyl-Porphyrins on Fe(001)- p(1 × 1)O. MICROMACHINES 2021; 12:mi12020191. [PMID: 33668500 PMCID: PMC7918924 DOI: 10.3390/mi12020191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 11/17/2022]
Abstract
In this paper we focus on the structural, electronic, and magnetic properties of Ni tetra-phenyl-porphyrins (NiTPP) grown on top of Fe(001)–p(1 × 1)O. Ordered thin films of metal TPP molecules are potentially interesting for organic electronic and spintronic applications, especially when they are coupled to a ferromagnetic substrate. Unfortunately, porphyrin layers deposited on top of ferromagnetic substrates do not generally show long-range order. In this work, we provide evidence of an ordered disposition of the organic film above the iron surface and we prove that the thin layer of iron oxide decouples the molecules from the substrate, thus preserving the molecular electronic features, especially the HOMO-LUMO gap, even when just a few organic layers are deposited. The effect of the exposure to molecular oxygen is also investigated and an increased robustness against oxidation with respect to the bare substrate is detected. Finally, we present our results for the magnetic analysis performed by spin resolved spectroscopy, finding a null magnetic coupling between the molecules and the substrate.
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25
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Mejri A, Herlem G, Picaud F. From Behavior of Water on Hydrophobic Graphene Surfaces to Ultra-Confinement of Water in Carbon Nanotubes. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:306. [PMID: 33504024 PMCID: PMC7911377 DOI: 10.3390/nano11020306] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 11/16/2022]
Abstract
In recent years and with the achievement of nanotechnologies, the development of experiments based on carbon nanotubes has allowed to increase the ionic permeability and/or selectivity in nanodevices. However, this new technology opens the way to many questionable observations, to which theoretical work can answer using several approximations. One of them concerns the appearance of a negative charge on the carbon surface, when the latter is apparently neutral. Using first-principles density functional theory combined with molecular dynamics, we develop here several simulations on different systems in order to understand the reactivity of the carbon surface in low or ultra-high confinement. According to our calculations, there is high affinity of the carbon atom to the hydrogen ion in every situation, and to a lesser extent for the hydroxyl ion. The latter can only occur when the first hydrogen attack has been achieved. As a consequence, the functionalization of the carbon surface in the presence of an aqueous medium is activated by its protonation, then allowing the reactivity of the anion.
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Affiliation(s)
| | | | - Fabien Picaud
- Laboratoire de Nanomédecine, Imagerie et Thérapeutiques, EA4662, UFR Sciences et Techniques, Centre Hospitalier Universitaire et Université de Bourgogne Franche Comté, 16 Route de Gray, 25030 Besançon, France; (A.M.); (G.H.)
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26
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Kakanakova-Georgieva A, Ivanov IG, Suwannaharn N, Hsu CW, Cora I, Pécz B, Giannazzo F, Sangiovanni DG, Gueorguiev GK. MOCVD of AlN on epitaxial graphene at extreme temperatures. CrystEngComm 2021. [DOI: 10.1039/d0ce01426e] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Appearance of luminescent centers with narrow spectral emission at room temperature in nanometer thin AlN is reported.
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Affiliation(s)
| | - Ivan G. Ivanov
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 581 83 Linköping
- Sweden
| | - Nattamon Suwannaharn
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 581 83 Linköping
- Sweden
| | - Chih-Wei Hsu
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 581 83 Linköping
- Sweden
| | - Ildikó Cora
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- Budapest
- Hungary
| | - Béla Pécz
- Centre for Energy Research
- Institute of Technical Physics and Materials Science
- Budapest
- Hungary
| | - Filippo Giannazzo
- Consiglio Nazionale delle Ricerche
- Istituto per la Microelettronica e Microsistemi
- Catania
- Italy
| | - Davide G. Sangiovanni
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 581 83 Linköping
- Sweden
| | - Gueorgui K. Gueorguiev
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 581 83 Linköping
- Sweden
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27
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Pécz B, Nicotra G, Giannazzo F, Yakimova R, Koos A, Kakanakova-Georgieva A. Indium Nitride at the 2D Limit. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006660. [PMID: 33225494 DOI: 10.1002/adma.202006660] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/01/2020] [Indexed: 06/11/2023]
Abstract
The properties of 2D InN are predicted to substantially differ from the bulk crystal. The predicted appealing properties relate to strong in- and out-of-plane excitons, high electron mobility, efficient strain engineering of their electronic and optical properties, and strong application potential in gas sensing. Until now, the realization of 2D InN remained elusive. In this work, the formation of 2D InN and measurements of its bandgap are reported. Bilayer InN is formed between graphene and SiC by an intercalation process in metal-organic chemical vapor deposition (MOCVD). The thickness uniformity of the intercalated structure is investigated by conductive atomic force microscopy (C-AFM) and the structural properties by atomic resolution transmission electron microscopy (TEM). The coverage of the SiC surface is very high, above 90%, and a major part of the intercalated structure is represented by two sub-layers of indium (In) bonded to nitrogen (N). Scanning tunneling spectroscopy (STS) measurements give a bandgap value of 2 ± 0.1 eV for the 2D InN. The stabilization of 2D InN with a pragmatic wide bandgap and high lateral uniformity of intercalation is demonstrated.
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Affiliation(s)
- Béla Pécz
- Centre for Energy Research, Institute for Technical Physics and Materials Science, Konkoly-Thege M. út 29-33, Budapest, 1121, Hungary
| | - Giuseppe Nicotra
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi, Strada VIII, n. 5, Zona Industriale, Catania, I-95121, Italy
| | - Filippo Giannazzo
- Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi, Strada VIII, n. 5, Zona Industriale, Catania, I-95121, Italy
| | - Rositsa Yakimova
- Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, 581 83, Sweden
| | - Antal Koos
- Centre for Energy Research, Institute for Technical Physics and Materials Science, Konkoly-Thege M. út 29-33, Budapest, 1121, Hungary
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28
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An J, Dai X, Guo R, Feng L, Zhao T. Ab initio study for molecular-scale adsorption, decomposition and desorption on AlN surfaces during MOCVD growth. Sci Rep 2020; 10:17840. [PMID: 33082396 PMCID: PMC7576780 DOI: 10.1038/s41598-020-72973-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 08/28/2020] [Indexed: 11/12/2022] Open
Abstract
Since AlGaN offers new opportunities for the development of the solid state ultraviolet (UV) luminescence, detectors and high-power electronic devices, the growth of AlN buffer substrate is concerned. However, the growth of AlN buffer substrate during MOCVD is regulated by an intricate interplay of gas-phase and surface reactions that are beyond the resolution of experimental techniques, especially the surface growth process. We used density-functional ab initio calculations to analyze the adsorption, decomposition and desorption of group-III and group-V sources on AlN surfaces during MOCVD growth in molecular-scale. For AlCH3 molecule the group-III source, the results indicate that AlCH3 is more easily adsorbed on AlN (0001) than (000\documentclass[12pt]{minimal}
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\begin{document}$$\overline{1}$$\end{document}1¯) surface on the top site. For the group-V source decomposition we found that NH2 molecule is the most favorable adsorption source and adsorbed on the top site. We investigated the adsorption of group-III source on the reconstructed AlN (0001) surface which demonstrates that NH2-rich condition has a repulsion effect to it. Furthermore, the desorption path of group-III and group-V radicals has been proposed. Our study explained the molecular-scale surface reaction mechanism of AlN during MOCVD and established the surface growth model on AlN (0001) surface.
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Menshutina N, Lebedev I, Lebedev E, Paraskevopoulou P, Chriti D, Mitrofanov I. A Cellular Automata Approach for the Modeling of a Polyamide and Carbon Aerogel Structure and Its Properties. Gels 2020; 6:gels6040035. [PMID: 33081053 PMCID: PMC7709703 DOI: 10.3390/gels6040035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 12/05/2022] Open
Abstract
In this work, a cellular automata (CA) approach was used to generate 3D structures of polyamide and carbon aerogels. Experimental results are used as initial data for materials’ digital representations and to verify the developed CA models. Based on the generated digital structures, a computer study of aerogels’ mechanical properties was conducted. The offered CA models can be applied for the development of new nanoporous materials such as aerogels of different nature and allow for a reduction in the amount of required full-scale experiments, consequently decreasing development time and costs of new material formulations.
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Affiliation(s)
- Natalia Menshutina
- International Science and Education Center for Transfer of Biopharmaceutical Technologies, Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia; (N.M.); (E.L.); (I.M.)
| | - Igor Lebedev
- International Science and Education Center for Transfer of Biopharmaceutical Technologies, Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia; (N.M.); (E.L.); (I.M.)
- Correspondence: ; Tel.: +7-495-495-0029
| | - Evgeniy Lebedev
- International Science and Education Center for Transfer of Biopharmaceutical Technologies, Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia; (N.M.); (E.L.); (I.M.)
| | - Patrina Paraskevopoulou
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece; (P.P.); (D.C.)
| | - Despoina Chriti
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece; (P.P.); (D.C.)
| | - Igor Mitrofanov
- International Science and Education Center for Transfer of Biopharmaceutical Technologies, Mendeleev University of Chemical Technology of Russia, Moscow 125047, Russia; (N.M.); (E.L.); (I.M.)
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Kakanakova-Georgieva A, Gueorguiev GK, Sangiovanni DG, Suwannaharn N, Ivanov IG, Cora I, Pécz B, Nicotra G, Giannazzo F. Nanoscale phenomena ruling deposition and intercalation of AlN at the graphene/SiC interface. NANOSCALE 2020; 12:19470-19476. [PMID: 32960193 DOI: 10.1039/d0nr04464d] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The possibility for kinetic stabilization of prospective 2D AlN was explored by rationalizing metal organic chemical vapor deposition (MOCVD) processes of AlN on epitaxial graphene. From the wide range of temperatures which can be covered in the same MOCVD reactor, the deposition was performed at the selected temperatures of 700, 900, and 1240 °C. The characterization of the structures by atomic force microscopy, electron microscopy and Raman spectroscopy revealed a broad range of surface nucleation and intercalation phenomena. These phenomena included the abundant formation of nucleation sites on graphene, the fragmentation of the graphene layers which accelerated with the deposition temperature, the delivery of excess precursor-derived carbon adatoms to the surface, as well as intercalation of sub-layers of aluminum atoms at the graphene/SiC interface. The conceptual understanding of these nanoscale phenomena was supported by our previous comprehensive ab initio molecular dynamics (AIMD) simulations of the surface reaction of trimethylaluminum, (CH3)3Al, precursor with graphene. A case of applying trimethylindium, (CH3)3In, precursor to epitaxial graphene was considered in a comparative way.
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Chergui S, Rhili K, Poorahong S, Siaj M. Graphene Oxide Membrane Immobilized Aptamer as a Highly Selective Hormone Removal. MEMBRANES 2020; 10:E229. [PMID: 32932581 PMCID: PMC7558482 DOI: 10.3390/membranes10090229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/09/2020] [Accepted: 09/11/2020] [Indexed: 12/12/2022]
Abstract
Three-dimensional (3D) reduced graphene oxide (rGO) modified by polyethyleneimine (PEI) was prepared and functionalized by fluorophore-labeled dexamethasone-aptamer (Flu-DEX-apt) via π-π stacking interaction. The rGO/PEI/Flu-DEX-apt was used as a selective membrane for dexamethasone hormone removal from water. The prepared rGO/PEI/Flu-DEX-apt membranes were stable, insoluble, and easily removable from liquid media. The membrane was characterized by Raman spectroscopy, scanning electron spectroscopy, and FTIR spectroscopy. The rGO/PEI/Flu-DEX-apt membrane showed high sensitivity and specificity toward the dexamethasone hormone in the presence of other steroid hormone analogs, such as progesterone, estrone, estradiol, and 19-norethindrone. The fluorescence and UV-visible spectroscopy were used to confirm the membranes performance and the quantification of hormones removal. The resulting data clearly show that the graphene oxide concentration influence the aptamers and analytes interaction (π-π stacking interaction). It was found that by varying the graphene oxide concentration yields to different porosities of rGO/PEI/Flu-DEX-apt membranes affects the adsorption recovery rate, as well as the specificity and selectivity toward the dexamethasone hormone.
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Affiliation(s)
| | | | | | - Mohamed Siaj
- Department of Chemistry, University of Quebec at Montreal, Montreal, QC H3C3P8, Canada; (S.C.); (K.R.); (S.P.)
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Yar M, Hashmi MA, Ayub K. The C2N surface as a highly selective sensor for the detection of nitrogen iodide from a mixture of NX3 (X = Cl, Br, I) explosives. RSC Adv 2020; 10:31997-32010. [PMID: 35518175 PMCID: PMC9056556 DOI: 10.1039/d0ra04930a] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/10/2020] [Indexed: 12/14/2022] Open
Abstract
Explosives are quite toxic and destructive; therefore, it is necessary to not only detect them but also remove them. The adsorption behavior of NX3 analytes (NCl3, NBr3 and NI3) over the microporous C2N surface was evaluated by DFT calculations. The nature of interactions between NX3 and C2N was characterized by adsorption energy, NCI, QTAIM, SAPT0, NBO, EDD and FMO analysis. The interaction energies of NX3 with C2N are in the range of −10.85 to −16.31 kcal mol−1 and follow the order of NCl3@C2N > NBr3@C2N > NI3@C2N, respectively. The 3D isosurfaces and 2D-RGD graph of NCI analysis qualitatively confirmed the existence of halogen bonding interactions among the studied systems. Halogen bonding was quantified by SAPT0 component energy analysis. The SAPT0 results revealed that ΔEdisp (56.75%) is the dominant contributor towards interaction energy, whereas contributions from ΔEelst and ΔEind are 29.41% and 14.34%, respectively. The QTAIM analysis also confirmed the presence of halogen bonding between atoms of NX3 and C2N surface. EDD analysis also validated NCI, QTAIM and NBO analysis. FMO analysis revealed that the adsorption of NI3 on the C2N surface caused the highest change in the EHOMO–LUMO gap (from 5.71 to 4.15 eV), and resulted in high sensitivity and selectivity of the C2N surface towards NI3, as compared to other analytes. It is worth mentioning that in all complexes, a significant difference in the EHOMO–LUMO gap was seen when electronic transitions occurred from the analyte to the C2N surface. Explosives are quite toxic and destructive; therefore, it is necessary to not only detect them but also remove them.![]()
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Affiliation(s)
- Muhammad Yar
- Department of Chemistry
- COMSATS University
- Abbottabad Campus
- Pakistan
| | | | - Khurshid Ayub
- Department of Chemistry
- COMSATS University
- Abbottabad Campus
- Pakistan
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The Reaction Thermodynamics during Plating Al on Graphene Process. MATERIALS 2019; 12:ma12020330. [PMID: 30669660 PMCID: PMC6356448 DOI: 10.3390/ma12020330] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 11/17/2022]
Abstract
This research explored a novel chemical reduction of organic aluminum for plating Al on a graphene surface. The thermodynamics of the Al plating reaction process were studied. The Al plating process consisted of two stages: the first was to prepare (C2H5)3Al. In this reaction, the ΔH(enthalpy) was 10.64 kcal/mol, the ΔG(Gibbs free energy) was 19.87 kcal/mol and the ΔS(entropy) was 30.9 cal/(mol·K); this was an endothermic reaction. In the second stage, the (C2H5)3Al decomposed into Al atoms, which were gradually deposited on the surface of the graphene and the Al plating formed. At 298.15 K, the ΔH was −20.21 kcal/mol, the ΔG was −54.822 kcal/mol, the ΔS was 116.08 cal/(mol·K) and the enthalpy change was negative, thus indicating an endothermic reaction.
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Epitaxial Growth of Orthorhombic GaFeO₃ Thin Films on SrTiO₃ (111) Substrates by Simple Sol-Gel Method. MATERIALS 2019; 12:ma12020254. [PMID: 30646559 PMCID: PMC6356229 DOI: 10.3390/ma12020254] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/06/2019] [Accepted: 01/08/2019] [Indexed: 11/17/2022]
Abstract
A Sol-gel method assisted with spin-coating has been successfully used to grow orthorhombic GaFeO3 epitaxial films on SrTiO3 (111) substrates for the first time. The film with Pna21 crystal structure has been grown along the c-axis. The rocking curve of (004) reflection shows that the Full-Width at Half-Maximum (FWHM) value could be determined to be 0.230°, indicating good single crystallinity and high quality. X-ray Φ scan reveals a three-fold symmetry of the substrate and a six-fold symmetry of the film, respectively. The in-plane domains rotate 60° from each other in the film. Uniform film with dense structure, columnar grains with similar grain size was obtained. The thickness of the film was evaluated to be ~170 nm. The roughness value (RMS) measured by AFM was 4.5 nm, revealing a flat film. The in-plane Magnetization versus Magnetic field (M-H) curve at 5 K performs a typical ferri- or ferromagnetic hysteresis loop with a saturated magnetization (Ms) value of 136 emu/cm3. The Curie temperature could be determined to be 174 K. Compared to Pulsed Laser Deposition (PLD), the sol-gel method can prepare large area films with low cost. These new films show promising applications in multiferroic devices.
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Molecular Dynamics Study on the Reverse Osmosis Using Multilayer Porous Graphene Membranes. NANOMATERIALS 2018; 8:nano8100805. [PMID: 30304786 PMCID: PMC6215223 DOI: 10.3390/nano8100805] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/04/2018] [Accepted: 10/05/2018] [Indexed: 01/25/2023]
Abstract
In this study, the reverse osmosis (RO) of a salt solution was investigated using a molecular dynamics method to explore the performance of a multilayer porous graphene membrane. The effects of the salt solution concentration, pressure, layer separation and pore offset on the RO performance of the membrane were investigated and the influences of the number of layers and the gradient structure were determined. The results show that as the salt solution concentration increases, the energy barrier of the water molecules passing through the bilayer porous graphene membranes changes slightly, indicating that the effect of the water flux on the membrane can be ignored. The salt rejection performance of the membrane improves with an increase in the concentration of the salt solution. When the pressure is increased, the energy barrier decreases, the water flux increases and the salt rejection decreases. When the layer separation of the bilayer porous graphene membrane is the same as the equilibrium spacing of the graphene membrane, the energy barrier is the lowest and the membrane water flux is the largest. The energy barrier of the bilayer porous graphene membrane increases with increasing layer separation, resulting in a decrease in the water flux of the membrane. The salt rejection increases with increasing layer separation. The water flux of the membrane decreases as the energy barrier increases with increasing pore offset and the salt rejection increases. The energy barrier effect is more pronounced for a larger number of graphene layers and the water flux of the membrane decreases because it is more difficult for the water molecules to pass through the porous graphene membrane. However, the salt rejection performance improves with the increase in the number of layers. The gradient pore structure enhances the energy barrier effect of the water molecules permeating through the membrane and the water flux of the membrane decreases. The salt rejection performance is improved by the gradient pore structure. The research results provide theoretical guidance for research on the RO performance of porous graphene membranes and the design of porous graphene membranes.
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Molecular Dynamics Investigation of Graphene Nanoplate Diffusion Behavior in Poly-α-Olefin Lubricating Oil. CRYSTALS 2018. [DOI: 10.3390/cryst8090361] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Graphene as a type of novel additive significantly enhanced the tribological performance of blended lubricating oil. However, the dispersibility of graphene with long-term stability in lubricating oil is still a challenge. Chemical modification for graphene, rather than using surfactants, provided a better method to improve the dispersibility of graphene in lubricants. In this study, the equilibrium molecular dynamics (EMD) simulations were carried out to investigate the diffusion behavior of graphene nanoplates in poly-α-olefin (PAO) lubricating oil. The effects of graphene-size, edge-functionalization, temperature, and pressure on the diffusion coefficient were studied. In order to understand the influence of edge-functionalization, three different functional groups were grafted to the edge of graphene nanoplates: COOH, COON(CH3)2, CONH(CH2)8CH3 (termed GO, MG, and AG, respectively). The EMD simulations results demonstrated that the relationships between diffusion coefficient and graphene-size and number of functional groups were linear while the temperature and pressure had a nonlinear influence on the diffusion coefficient. It was found that the larger dimension and more functional groups provided the lower diffusion coefficient. AG with eight CONH(CH2)8CH3 groups exhibited the lowest diffusion coefficient. Furthermore, the experimental results and radial distribution function for graphene-PAO illustrated that the diffusion coefficient reflected the dispersibility of nanoparticles in nanofluids to some degree. To our best knowledge, this study is the first time the diffusion behavior of graphene in PAO lubricating oil was investigated using EMD simulations.
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