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Fukuda M, Ozaki T. Electronic band structure change with structural transition of buckled Au 2X monolayers induced by strain. Phys Chem Chem Phys 2024; 26:3367-3374. [PMID: 38204303 DOI: 10.1039/d3cp03135g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
This study investigates the strain-induced structural transitions of η ↔ θ and the changes in electronic band structures of Au2X (X = S, Se, Te, Si, Ge) and Au4SSe. We focus on Au2S monolayers, which can form multiple meta-stable monolayers theoretically, including η-Au2S, a buckled penta-monolayer composed of a square Au lattice and S adatoms. The θ-Au2S is regarded as a distorted structure of η-Au2S. Based on density functional theory (DFT) calculations using a generalized gradient approximation, the conduction and the valence bands of θ-Au2S intersect at the Γ point, leading to linear dispersion, whereas η-Au2S has a band gap of 1.02 eV. The conduction band minimum depends on the specific Au-Au bond distance, while the valence band maximum depends on both Au-S and Au-Au interactions. The band gap undergoes significant changes during the η ↔ θ phase transition of Au2S induced by applying tensile or compressive in-plane biaxial strain to the lattice. Moreover, substituting S atoms with other elements alters the electronic band structures, resulting in a variety of physical properties without disrupting the fundamental Au lattice network. Therefore, the family of Au2X monolayers holds potential as materials for atomic scale network devices.
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Affiliation(s)
- Masahiro Fukuda
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
| | - Taisuke Ozaki
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
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2
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Xue Y, Gao L, Ren W, Shai X, Wei T, Zeng C, Wang H. Prediction of 2D group-11 chalcogenides: insights into novel auxetic M 2X (M = Cu, Ag, Au; X = S, Se, Te) monolayers. Phys Chem Chem Phys 2023; 25:32323-32329. [PMID: 37994579 DOI: 10.1039/d3cp04397e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Two-dimensional (2D) auxetic materials have recently attracted considerable research interest due to their excellent mechanical properties and diverse applications, surpassing those of three-dimensional (3D) materials. This study focuses on the theoretical prediction of mechanical properties and auxeticity in 2D M2X (M = Cu, Ag, Au; X = S, Se, Te) monolayers using first-principles calculations. Our results indicate that the dynamically stable monolayers include low-energy α-Cu2S, α-Cu2Se, α-Cu2Te, β-Ag2S, β-Ag2Se, α-Ag2Te, β-Au2S, β-Au2Se and α-Au2Te. These M2X monolayers possess positive Poisson's ratios (PR) ranging from 0.09 to 0.52, as well as Young's moduli ranging from 19.92 to 35.42 N m-1 in x and y directions. Specially, α-Cu2S exhibits the lowest negative PR in θ = 45° × n (n = 1, 2, 3, 4) directions. The Poisson's function (PF) can be adjusted by increasing tensile strains. The β-phase monolayers exhibit positive PF with a linear change. Interestingly, the transition from positive to negative PF occurs in the α-Cu2S and α-Ag2Te monolayers at strains greater than +3% and +4%, respectively, while the α-Cu2Se, α-Cu2Te and α-Au2Te monolayers maintain positive PF within the range of 0% to +6% strains. Furthermore, taking α-Cu2S (α-Cu2Te) as an example, the mechanism underlying negative (positive) PF is demonstrated to involve increased (decreased) bond angles, decreased thickness, and weakened (enhanced) d(M)-p(X) orbital coupling. The findings of this study not only enrich the family of 2D group-11 chalcogenides but also provide insights into their mechanical properties, thereby expanding their potential applications in mechanics.
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Affiliation(s)
- Yufei Xue
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
| | - Lei Gao
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
- State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, Yunnan, China.
| | - Weina Ren
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
| | - Xuxia Shai
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
| | - Tingting Wei
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
| | - Chunhua Zeng
- Institute of Physical and Engineering Science/Faculty of Science, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.
| | - Hua Wang
- State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, Yunnan, China.
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Jin N, Sun Y, Shi W, Wang P, Nagaoka Y, Cai T, Wu R, Dube L, Nyiera HN, Liu Y, Mani T, Wang X, Zhao J, Chen O. Type-I CdS/ZnS Core/Shell Quantum Dot-Gold Heterostructural Nanocrystals for Enhanced Photocatalytic Hydrogen Generation. J Am Chem Soc 2023; 145:21886-21896. [PMID: 37768875 DOI: 10.1021/jacs.3c06065] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Developing Type-I core/shell quantum dots is of great importance toward fabricating stable and sustainable photocatalysts. However, the application of Type-I systems has been limited due to the strongly confined photogenerated charges by the energy barrier originating from the wide-bandgap shell material. In this project, we found that through the decoration of Au satellite-type domains on the surface of Type-I CdS/ZnS core/shell quantum dots, such an energy barrier can be effectively overcome and an over 400-fold enhancement of photocatalytic H2 evolution rate was achieved compared to bare CdS/ZnS quantum dots. Transient absorption spectroscopic studies indicated that the charges can be effectively extracted and subsequently transferred to surrounding molecular substrates in a subpicosecond time scale in such hybrid nanocrystals. Based on density functional theory calculations, the ultrafast charge separation rates were ascribed to the formation of intermediate Au2S layer at the semiconductor-metal interface, which can successfully offset the energy confinement introduced by the ZnS shell. Our findings not only provide insightful understandings on charge carrier dynamics in semiconductor-metal heterostructural materials but also pave the way for the future design of quantum dot-based hybrid photocatalytic systems.
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Affiliation(s)
- Na Jin
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yonglei Sun
- Institute of Materials Science, University of Connecticut, Storrs Mansfield, Connecticut 06269, United States
| | - Wenwu Shi
- School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China
- Institute of Information Technology, Shenzhen Institute of Information Technology, Shenzhen 518172, China
| | - Ping Wang
- Key Laboratory of Preparation and Applications of Environmental Friendly Materials of the Ministry of Education, College of Chemistry, Jilin Normal University, Changchun 130103, China
| | - Yasutaka Nagaoka
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Tong Cai
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Rongzhen Wu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lacie Dube
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hawi N Nyiera
- Department of Chemistry, University of Connecticut, Storrs Mansfield, Connecticut 06269, United States
| | - Yuzi Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Tomoyasu Mani
- Department of Chemistry, University of Connecticut, Storrs Mansfield, Connecticut 06269, United States
| | - Xinzhong Wang
- Institute of Information Technology, Shenzhen Institute of Information Technology, Shenzhen 518172, China
| | - Jing Zhao
- Institute of Materials Science, University of Connecticut, Storrs Mansfield, Connecticut 06269, United States
- Department of Chemistry, University of Connecticut, Storrs Mansfield, Connecticut 06269, United States
| | - Ou Chen
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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Yu J, Zhou R, Shi H, Duan Y. Tunable Intrinsic Phonon Mode versus Anomalous Thermal Transport in Two-Dimensional Strongly Anharmonic Group IB Chalcogenides A 2IBSe 1/2Te 1/2 (A IB = Cu, Ag, or Au). J Phys Chem Lett 2023; 14:7975-7980. [PMID: 37647055 DOI: 10.1021/acs.jpclett.3c01830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Group IB chalcogenides, as promising thermoelectric materials, have ultralow thermal transport. Here, we propose a peculiar intrinsic B2 phonon mode that includes the in-plane rotational and stretching vibrations of metal atoms in two-dimensional A2IBSe1/2Te1/2 (AIB = Cu, Ag, or Au). The B2 mode is sensitive to the metal-atom mass, temperature, and strain for effectively tuning the lattice thermal conductivity. The in-plane stretching vibration leads to an unexpected increase in the lattice thermal conductivity from Cu to Ag and to Au systems, in contrast to Keyes' theory. The s(I) phase can be stabilized by the temperature-hardened B2 mode to reduce the lattice thermal conductivity, following the ∼T-0.59 instead of the traditional ∼T-1 trend. The s(II)-to-s(I) phase transition is driven by the strain-softened B2 mode to greatly enhance thermal transport via weakening the anharmonicity. Our work establishes the relationship of tunable intrinsic phonon mode versus thermal transport in two-dimensional group IB chalcogenides.
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Affiliation(s)
- Jinzi Yu
- School of Materials and Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Ran Zhou
- School of Materials and Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
- Department of Physics, Beihang University, Beijing 100191, China
| | - Hongliang Shi
- Department of Physics, Beihang University, Beijing 100191, China
| | - Yifeng Duan
- School of Materials and Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
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5
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Zhou R, Liang H, Duan Y, Wei SH. Enhanced Anharmonicity by Forming Low-Symmetry Off-Center Phase: The Case of Two-Dimensional Group-IB Chalcogenides. J Phys Chem Lett 2023; 14:737-742. [PMID: 36649585 DOI: 10.1021/acs.jpclett.2c03342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Enhanced anharmonicity is required to achieve many interesting phenomena in thermoelectricity, superconductivity, ferroelectricity, etc. Here, we propose a novel mechanism for enhancing anharmonicity by forming the low-symmetry off-center ground state, such as the s(II) phase, in two-dimensional AIB2X chalcogenides (AIB = Cu, Ag and Au; X = S, Se, and Te). In this system, the in-plane rotational phonon mode introduces a much stronger anharmonicity in the distorted s(II) phase than in the nondistorted s(I) phase. We show that the stabilities of the s(I) and s(II) phases arise from the ionicity and the ionic size; for example, the low ionicity and the small ionic size favor the s(II) phase. We further demonstrate that the anharmonicity can be tuned by controlling the strain-induced s(II)-to-s(I) phase transition, which explains the anomalous lattice thermal conductivity. Our work relates anharmonicity to symmetry-breaking structural distortion and widens the ways to design excellent thermoelectric materials.
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Affiliation(s)
- Ran Zhou
- School of Materials and Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Hanpu Liang
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Yifeng Duan
- School of Materials and Physics, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Su-Huai Wei
- Beijing Computational Science Research Center, Beijing 100193, China
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6
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Taheri A, Pisana S, Singh CV. Extraordinary lattice thermal conductivity of gold sulfide monolayers. NANOSCALE ADVANCES 2022; 4:2873-2883. [PMID: 36132007 PMCID: PMC9418960 DOI: 10.1039/d2na00019a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
Gold sulfide monolayers (α-, β-Au2S, α-, β-, γ-AuS) have emerged as a new class of two-dimensional (2D) materials with appealing properties such as high thermal and dynamical stability, oxidation resistance, and excellent electron mobility. However, their thermal properties are still unexplored. In this study, based on first-principles calculations and the Peierls-Boltzmann transport equation, we report the lattice thermal conductivity (κ) and related phonon thermal properties of all members of this family. Our results show that gold sulfide monolayers have lattice thermal conductivity spanning almost three orders of magnitude, from 0.04 W m-1 K-1 to 10.62 W m-1 K-1, with different levels of anisotropy. Particularly, our results demonstrate that β-Au2S with ultralow κ aa = 0.06 W m-1 K-1 and κ bb = 0.04 W m-1 K-1 along the principal in-plane directions, has one of the lowest κ values that have been reported for a 2D material, well below that of PbSe. This extremely low lattice thermal conductivity can be attributed to its flattened phonon branches and low phonon group velocity, high anharmonicity, and short phonon lifetimes. Our results may provide insight into the application of gold sulfide monolayers as thermoelectric materials, and motivate future κ measurements of gold sulfide monolayers.
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Affiliation(s)
- Armin Taheri
- Department of Electrical Engineering and Computer Science, York University Toronto Ontario M3J1P3 Canada
| | - Simone Pisana
- Department of Electrical Engineering and Computer Science, York University Toronto Ontario M3J1P3 Canada
- Department of Physics and Astronomy, York University Toronto Ontario M3J1P3 Canada
| | - Chandra Veer Singh
- Department of Materials Science and Engineering, University of Toronto Toronto Ontario M5S 3E4 Canada
- Department of Mechanical and Industrial Engineering, University of Toronto Toronto Ontario M5S 3G8 Canada
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7
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Effects of 3d transition metal impurities and vacancy defects on electronic and magnetic properties of pentagonal Pd 2S 4: competition between exchange splitting and crystal fields. Sci Rep 2022; 12:10838. [PMID: 35761014 PMCID: PMC9237093 DOI: 10.1038/s41598-022-14780-z] [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: 02/12/2022] [Accepted: 06/13/2022] [Indexed: 11/27/2022] Open
Abstract
In this paper, we first investigate the electronic properties of the two-dimensional structure of dichalcogenide Pd2S4. These properties strongly depend on the crystal field splitting which can change by atomic vacancies (S and Pd vacancies). The main purpose of the present paper is to create remarkable magnetic properties in the system by adding 3d transition metal atoms where the presence of Mn, Cr, and Fe creates the exchange interaction in the system as well as change in the crystal field. The created magnetic properties strongly depend on the competition between exchange interaction and crystal field to separate the levels of d orbitals. In addition, the presence of the transition metals in the structures with S and Pd vacancy has been investigated carefully. The calculations demonstrate that we can achieve an extensive range of magnetic moment up to 3.131 \documentclass[12pt]{minimal}
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\begin{document}$${\mu }_{B}$$\end{document}μB. The maximum one is obtained in the presence of Mn and absence of sulfur while some of the doped structures does not have magnetic moment. Our results show that Pd vacancy in the presence of Cr, Mn and Fe metals increases the magnetic property of the Pd2S4 structure. The extensiveness and variety of the obtained properties can be used for different magnetic and non-magnetic applications.
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Shangguan W, Yan C, Li W, Long C, Liu L, Qi C, Li Q, Zhou Y, Guan Y, Gao L, Cai J. Two-dimensional semiconductor materials with high stability and electron mobility in group-11 chalcogenide compounds: MNX (M = Cu, Ag, Au; N = Cu, Ag, Au; X = S, Se, Te; M ≠ N). NANOSCALE 2022; 14:4271-4280. [PMID: 35244105 DOI: 10.1039/d1nr06971c] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is still an urgent task to find new two-dimensional (2D) semiconductor materials with a suitable band gap, high stability and high mobility for the applications of next generation electronic devices. Based on first-principles calculations, we report a new class of 2D group-11-chalcogenide trielement monolayers (MNX, where M = Cu, Ag, Au; N = Cu, Ag, Au; X = S, Se, Te; M ≠ N) with a wide band gap, excellent stability (dynamic stability, thermodynamic stability and environmental stability) and high mobility. At the mixed density functional level, the energy band gap extends from 0.61 eV to 2.65 eV, covering the ultraviolet-A and visible light regions, which is critical for a broadband optical response. For δ-MNX monolayers, the carrier mobility is as high as 104 cm2 V-1 s-1 at room temperature. In particular, the mobility of δ-AgAuS is as high as 6.94 × 104 cm2 V-1 s-1, which is of great research significance for the application of electronic devices in the future. Based on the above advantages, group-11 chalcogenide MNX monomolecular films have broad prospects in the field of nanoelectronics and optoelectronics in the future.
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Affiliation(s)
- Wei Shangguan
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Cuixia Yan
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Wenqing Li
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Chen Long
- Shenzhen Institute of Advanced Electronic Materials, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518103, People's Republic of China.
| | - Liming Liu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Chenchen Qi
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Qiuyang Li
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Yan Zhou
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Yurou Guan
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
| | - Lei Gao
- Faculty of Science, Kunming University of Science and Technology, Kunming, Yunnan 650000, People's Republic of China.
| | - Jinming Cai
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, People's Republic of China.
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Liu L, Hu X, Wang Y, Krasheninnikov AV, Chen Z, Sun L. Tunable electronic properties and enhanced ferromagnetism in Cr 2Ge 2Te 6monolayer by strain engineering. NANOTECHNOLOGY 2021; 32:485408. [PMID: 34348248 DOI: 10.1088/1361-6528/ac1a94] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
Recently, as a new representative of Heisenberg's two-dimensional (2D) ferromagnetic materials, 2D Cr2Ge2Te6(CGT), has attracted much attention due to its intrinsic ferromagnetism. Unfortunately, the Curie temperature (TC) of CGT monolayer is only 22 K, which greatly hampers the development of the applications based on the CGT materials. Herein, by means of density functional theory computations, we explored the electronic and magnetic properties of CGT monolayer under the applied strain. It is demonstrated that the band gap of CGT monolayer can be remarkably modulated by applying the tensile strain, which first increases and then decreases with the increase of tensile strain. In addition, the strain can increase the Curie temperature and magnetic moment, and thus largely enhance the ferromagnetism of CGT monolayer. Notably, the obvious enhancement ofTCby 191% can be achieved at 10% strain. These results demonstrate that strain engineering can not only tune the electronic properties, but also provide a promising avenue to improve the ferromagnetism of CGT monolayer. The remarkable electronic and magnetic response to biaxial strain can also facilitate the development of CGT-based spin devices.
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Affiliation(s)
- Lifei Liu
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Xiaohui Hu
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Yifeng Wang
- College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, People's Republic of China
- Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing 211816, People's Republic of China
| | - Arkady V Krasheninnikov
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany
- Department of Applied Physics, Aalto University School of Science, PO Box 11100, FI-00076 Aalto, Finland
| | - Zhongfang Chen
- Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931 United States of America
| | - Litao Sun
- SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Collaborative Innovation Center for Micro/Nano Fabrication, Device and System, Southeast University, Nanjing 210096, People's Republic of China
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10
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Mohanta MK, Arora A, De Sarkar A. Conflux of tunable Rashba effect and piezoelectricity in flexible magnesium monochalcogenide monolayers for next-generation spintronic devices. NANOSCALE 2021; 13:8210-8223. [PMID: 33885124 DOI: 10.1039/d1nr00149c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The coupling of piezoelectric properties with Rashba spin-orbit coupling (SOC) has proven to be the limit breaker that paves the way for a self-powered spintronic device (ACS Nano, 2018, 12, 1811-1820). For further advancement in next-generation devices, a new class of buckled, hexagonal magnesium-based chalcogenide monolayers (MgX; X = S, Se, Te) have been predicted which are direct band gap semiconductors satisfying all the stability criteria. The MgTe monolayer shows a strong SOC with a Rashba constant of 0.63 eV Å that is tunable to the extent of ±0.2 eV Å via biaxial strain. Also, owing to its broken inversion symmetry and buckling geometry, MgTe has a very large in-plane as well as out-of-plane piezoelectric coefficient. These results indicate its prospects for serving as a channel semiconducting material in self-powered piezo-spintronic devices. Furthermore, a prototype for a digital logic device can be envisioned using the ac pulsed technology via a perpendicular electric field. Heat transport is significantly suppressed in these monolayers as observed from their intrinsic low lattice thermal conductivity at room temperature: MgS (9.32 W m-1 K-1), MgSe (4.93 W m-1 K-1) and MgTe (2.02 W m-1 K-1). Further studies indicate that these monolayers can be used as photocatalytic materials for the simultaneous production of hydrogen and oxygen on account of having suitable band edge alignment and high charge carrier mobility. This work provides significant theoretical insights into both the fundamental and applied properties of these new buckled MgX monolayers, which are highly suitable for futuristic applications at the nanoscale in low-power, self-powered multifunctional electronic and spintronic devices and solar energy harvesting.
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Affiliation(s)
- Manish Kumar Mohanta
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Manauli, Mohali, Punjab-140306, India.
| | - Anu Arora
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Manauli, Mohali, Punjab-140306, India.
| | - Abir De Sarkar
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Manauli, Mohali, Punjab-140306, India.
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11
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Shao L, Duan X, Li Y, Zeng F, Ye H, Ding P. Two-dimensional Ga 2O 2 monolayer with tunable band gap and high hole mobility. Phys Chem Chem Phys 2021; 23:666-673. [PMID: 33336669 DOI: 10.1039/d0cp05171c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By means of density functional theory and unbiased structure search computations, we systematically investigated the stability and electronic properties of a new Ga2O2 monolayer. The phonon spectra and ab initio molecular dynamics simulations show that the Ga2O2 monolayer is dynamically and thermally stable. Moreover, it also shows superior open-air stability. In particular, the Ga2O2 monolayer is an indirect semiconductor with a wide band gap of 2.752 eV and high hole mobility of 4720 cm2 V-1 s-1. Its band gap can be tuned flexibly in a large range by applied strain and layer control. It exhibits high absorption coefficients (>105 cm-1) in the ultraviolet region. The combined novel electronic properties of the Ga2O2 monolayer imply that it is a highly promising material for future applications in electronics and optoelectronics.
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Affiliation(s)
- Li Shao
- School of Materials, Zhengzhou University of Aeronautics, Zhengzhou 450015, China.
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12
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Mohanta MK, De Sarkar A. Interfacial hybridization of Janus MoSSe and BX (X = P, As) monolayers for ultrathin excitonic solar cells, nanopiezotronics and low-power memory devices. NANOSCALE 2020; 12:22645-22657. [PMID: 33155008 DOI: 10.1039/d0nr07000a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this work, we explored the interfacial two-dimensional (2D) physics and significant advancements in the application prospects of MoSSe monolayer when it is combined with a boron pnictide (BP, BAs) monolayer in a van der Waals heterostructure (vdWH) setup. The constructed vdWHs were found to be mechanically and dynamically stable, and they form type-II p-n heterojunctions. Thus, the photogenerated electron-hole pairs are spatially separated. In the BX/MoSSe vdWHs, the BX monolayer serves as excellent donor material for MoSSe, having an ideal donor band gap of ∼1.3 eV. The small value of the conduction band offset (CBO) between the individual monolayers in the vdWHs makes it an excellent candidate for solar energy harvesting in excitonic solar cells, where the power conversion efficiencies were calculated to be 22.97% (BP/MoSSe) and 20.86% (BAs/MoSSe). Also, more than four-fold enhancement in the out-of-plane piezoelectric coefficient (d33) was observed in the MoSSe-based vdWH relative to that in the MoS2-based vdWH owing to the intrinsic built-in vertical electric field in MoSSe. This is consistent with the out-of-plane piezoelectricity brought about by the alteration in symmetry at the metal-semiconductor Schottky junction, which has been observed experimentally [M.-M. Yang, Z.-D. Luo, Z. Mi, J. Zhao, S. P. E and M. Alexe, Nature, 2020, 584, 377-381]. The results obtained in this work provide useful insights into the design of nanomaterials for future applications in nano-optoelectronics, more efficient excitonic solar cells, and nanoelectromechanical systems (NEMS). Furthermore, this work demonstrates outstanding potential for the application of these vdWHs in superfast electronics, including low-power digital data storage and memory devices, where the tunnel current between the source and drain is effectively tunable using a normal electric field of small magnitude serving as the gate voltage.
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Affiliation(s)
- Manish Kumar Mohanta
- Institute of Nano Science and Technology, Phase 10, Sector 64, Mohali, Punjab - 160062, India.
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Kuklin AV, Gao L, Zhang H, Ågren H. Two-Dimensional Gold Halides: Novel Semiconductors with Giant Spin-Orbit Splitting and Tunable Optoelectronic Properties. J Phys Chem Lett 2020; 11:9759-9765. [PMID: 33142056 DOI: 10.1021/acs.jpclett.0c02788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We introduce a new family of 2D materials with unique structure and optoelectronic properties, namely, single-layer gold(I) halides (AuHals). We propose their stability as well as structural, electronic, and optical properties using first-principles calculations. The cleavage energy is found to be similar to that of graphene from graphite, indicating the possibility for mechanical exfoliation. We show that AuHals are stable and have tunable direct (AuBr) and indirect (AuI) band gaps depending on the number of layers. We discuss the possible origin of the giant spin-orbit coupling (SOC) induced conduction band splitting in terms of orbital-decomposed band structure to guide future investigations on the design of materials with highly effective SOC. Exceptionally high excitonic binding energy, high hole mobility, and tunable band gaps indicate that AuHals are promising candidates for optoelectronic devices with excellent performance.
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Affiliation(s)
- Artem V Kuklin
- Division of Science and Innovations, Siberian Federal University, 79 Svobodny pr., Krasnoyarsk 660041, Russia
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Lingfeng Gao
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen 518060, P. R. China
| | - Han Zhang
- Institute of Microscale Optoelectronics, Collaborative Innovation Centre for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, Guangdong Laboratory of Artificial Intelligence and Digital Economy (SZ), Shenzhen University, Shenzhen 518060, P. R. China
| | - Hans Ågren
- Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
- College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, P. R. China
- Tomsk State University, 36 Lenin Avenue, Tomsk, Russia
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Sun M, Yan Y, Schwingenschlögl U. Beryllene: A Promising Anode Material for Na- and K-Ion Batteries with Ultrafast Charge/Discharge and High Specific Capacity. J Phys Chem Lett 2020; 11:9051-9056. [PMID: 33044084 DOI: 10.1021/acs.jpclett.0c02426] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We predict two-dimensional Be materials, α- and β-beryllene. In α-beryllene each Be atom binds to six other Be atoms in a planar scheme, whereas β-beryllene consists of two stacked α-beryllene monolayers. Both α- and β-beryllene are found to be highly stable, as demonstrated by high cohesive energies close to that of bulk Be, an absence of imaginary phonon modes, and high melting points. Both materials are metallic, indicating potential applications in Na-ion and K-ion batteries, which are explored in detail. The diffusion barriers of Na (K) on α- and β-beryllene are found to be only 9 (3) and 4 (5) meV, respectively. In particular, the diffusion barrier of K on α-beryllene exhibits the lowest ever recorded value in two-dimensional materials, suggesting the possibility of ultrafast charge/discharge. As the theoretical specific capacities of Na/K on α- and β-beryllene are found to be 1487/1322 and 743/743 mA h g-1, respectively, the storage capacity is ultrahigh.
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Affiliation(s)
- Minglei Sun
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Yuan Yan
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Udo Schwingenschlögl
- Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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Chen X, Wang D, Liu X, Li L, Sanyal B. Two-Dimensional Square-A 2B (A = Cu, Ag, Au, and B = S, Se): Auxetic Semiconductors with High Carrier Mobilities and Unusually Low Lattice Thermal Conductivities. J Phys Chem Lett 2020; 11:2925-2933. [PMID: 32223172 DOI: 10.1021/acs.jpclett.0c00613] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using evolutionary structure search combined with ab initio theory, we investigate the electronic, thermal, and mechanical properties of two-dimensional (2D) A2B (A = Cu, Ag, Au, and B = S, Se) auxetic semiconductors. Two types of structures are found to have low energy, namely, s(I/II)-A2B, which have direct bandgaps in the range 1.09-2.60 eV and high electron mobilities. Among these semiconductors, Cu2B and Ag2B have light holes with 2 orders of magnitude larger mobility than the heavy holes, up to 9.51 × 104 cm2 V-1 s-1, giving the possibility of achieving highly anisotropic hole transport with the application of a uniaxial strain. Due to the ionic bonding nature, s-A2B structures have unusually low lattice thermal conductivities down to 1.5 W m-1 K-1 at 300 K, which are quite promising for new generation thermoelectric devices. Besides, s-A2B structures show extraordinary flexibility with ultralow Young's moduli (down to 20 N/m), which are lower than most previously reported 2D materials. Moreover, under strain along the diagonal direction, five of the structures have in-plane negative Poisson's ratios.
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Affiliation(s)
- Xin Chen
- Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
| | - Duo Wang
- Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
| | - Xiaobiao Liu
- School of Sciences, Henan Agricultural University, Zhengzhou 450002, People's Republic of China
| | - Linyang Li
- School of Science, Hebei University of Technology, Tianjin 300401, People's Republic of China
| | - Biplab Sanyal
- Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
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Mohanta MK, Fathima IS, De Sarkar A. Exceptional mechano-electronic properties in the HfN2 monolayer: a promising candidate in low-power flexible electronics, memory devices and photocatalysis. Phys Chem Chem Phys 2020; 22:21275-21287. [DOI: 10.1039/d0cp02999h] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The response of the electronic properties of the HfN2 monolayer to external perturbation such as strain and electric fields has been investigated using density functional theory calculations for its device-based applications and photocatalysis.
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Carro P, Salvarezza RC. Gold adatoms modulate sulfur adsorption on gold. NANOSCALE 2019; 11:19341-19351. [PMID: 31435624 DOI: 10.1039/c9nr05709a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Sulfur adsorption on Au(111) at high coverage has been studied by density functional calculations. In this case S species organize into rectangular structures containing 8 S atoms irrespective of the S source, which have been alternatively assigned to adsorbed monomeric S, adsorbed S2, adsorbed monomeric plus S2 species, and gold sulfide. We found that monomeric S at the high coverage organizes into S2 species that are stabilized into the 8-S structures by Au adatoms, forming gold disulfide complexes (Au-(S2)4). The Au atoms could be provided by decomposition of more diluted AuS3 containing phases, as recently proposed, and direct removal from terraces and step edges, both explaining the surface coverage of vacancy islands coexisting with the 8-S structures. The gold-disulfide complexes capture the disorder shown in the experimental STM images, explain the intrigued features of XPS, and also, give a smooth pathway to gold sulfide formation at higher temperatures. More importantly, the gold-disulfide complexes allow a unified picture of the gold-sulfur surface chemistry at high coverage for thiols and adsorbed sulfur species where the surface chemistry remains under discussion.
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Affiliation(s)
- Pilar Carro
- Área de Química Física, Departamento de Química, Facultad de Ciencias, Universidad de La Laguna, Instituto de Materiales y Nanotecnología, Avda. Francisco Sánchez, s/n 38200-La Laguna, Tenerife, Spain
| | - Roberto C Salvarezza
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET, La Plata 1900, Argentina.
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