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Dai B, Su Y, Guo Y, Wu C, Xie Y. Recent Strategies for the Synthesis of Phase-Pure Ultrathin 1T/1T' Transition Metal Dichalcogenide Nanosheets. Chem Rev 2024; 124:420-454. [PMID: 38146851 DOI: 10.1021/acs.chemrev.3c00422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The past few decades have witnessed a notable increase in transition metal dichalcogenide (TMD) related research not only because of the large family of TMD candidates but also because of the various polytypes that arise from the monolayer configuration and layer stacking order. The peculiar physicochemical properties of TMD nanosheets enable an enormous range of applications from fundamental science to industrial technologies based on the preparation of high-quality TMDs. For polymorphic TMDs, the 1T/1T' phase is particularly intriguing because of the enriched density of states, and thus facilitates fruitful chemistry. Herein, we comprehensively discuss the most recent strategies for direct synthesis of phase-pure 1T/1T' TMD nanosheets such as mechanical exfoliation, chemical vapor deposition, wet chemical synthesis, atomic layer deposition, and more. We also review frequently adopted methods for phase engineering in TMD nanosheets ranging from chemical doping and alloying, to charge injection, and irradiation with optical or charged particle beams. Prior to the synthesis methods, we discuss the configuration of TMDs as well as the characterization tools mostly used in experiments. Finally, we discuss the current challenges and opportunities as well as emphasize the promising fields for the future development.
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Affiliation(s)
- Baohu Dai
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yueqi Su
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yuqiao Guo
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Changzheng Wu
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Yi Xie
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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2
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Liu F, Fan Z. Defect engineering of two-dimensional materials for advanced energy conversion and storage. Chem Soc Rev 2023; 52:1723-1772. [PMID: 36779475 DOI: 10.1039/d2cs00931e] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
In the global trend towards carbon neutrality, sustainable energy conversion and storage technologies are of vital significance to tackle the energy crisis and climate change. However, traditional electrode materials gradually reach their property limits. Two-dimensional (2D) materials featuring large aspect ratios and tunable surface properties exhibit tremendous potential for improving the performance of energy conversion and storage devices. To rationally control the physical and chemical properties for specific applications, defect engineering of 2D materials has been investigated extensively, and is becoming a versatile strategy to promote the electrode reaction kinetics. Simultaneously, exploring the in-depth mechanisms underlying defect action in electrode reactions is crucial to provide profound insight into structure tailoring and property optimization. In this review, we highlight the cutting-edge advances in defect engineering in 2D materials as well as their considerable effects in energy-related applications. Moreover, the confronting challenges and promising directions are discussed for the development of advanced energy conversion and storage systems.
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Affiliation(s)
- Fu Liu
- Department of Chemistry, City University of Hong Kong, Hong Kong 999077, China.
| | - Zhanxi Fan
- Department of Chemistry, City University of Hong Kong, Hong Kong 999077, China. .,Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), City University of Hong Kong, Hong Kong 999077, China.,Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
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3
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Gavhane D, van Huis MA. Thermal Stability and Sublimation of Two-Dimensional Co 9Se 8 Nanosheets for Ultrathin and Flexible Nanoelectronic Devices. ACS APPLIED NANO MATERIALS 2023; 6:2421-2428. [PMID: 36875179 PMCID: PMC9972340 DOI: 10.1021/acsanm.2c04640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/25/2023] [Indexed: 06/18/2023]
Abstract
An understanding of the structural and compositional stability of nanomaterials is significant from both fundamental and technological points of view. Here, we investigate the thermal stability of half-unit-cell thick two-dimensional (2D) Co9Se8 nanosheets that are exceptionally interesting because of their half-metallic ferromagnetic properties. By employing in situ heating in the transmission electron microscope (TEM), we find that the nanosheets show good structural and chemical stability without changes to the cubic crystal structure until sublimation of the nanosheets starts at temperatures between 460 and 520 °C. The real-time observations of the sublimation process show preferential removal at {110} type crystal facets. From an analysis of sublimation rates at various temperatures, we find that the sublimation occurs through noncontinuous and punctuated mass loss at lower temperatures while the sublimation is continuous and uniform at higher temperatures. Our findings provide an understanding of the nanoscale structural and compositional stability of 2D Co9Se8 nanosheets, which is of importance for their reliable application and sustained performance as ultrathin and flexible nanoelectronic devices.
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Li S, Nishimura T, Maruyama M, Okada S, Nagashio K. Experimental verification of SO 2 and S desorption contributing to defect formation in MoS 2 by thermal desorption spectroscopy. NANOSCALE ADVANCES 2023; 5:405-411. [PMID: 36756254 PMCID: PMC9846482 DOI: 10.1039/d2na00636g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 11/25/2022] [Indexed: 06/18/2023]
Abstract
The defect-free surface of MoS2 is of high importance for applications in electronic devices. Theoretical calculations have predicted that oxidative etching could be responsible for sulfur vacancy formation. No direct experimental evidence, however, points out the role of adsorbed oxygen on sulfur vacancy formation for MoS2, especially on an insulating SiO2/Si substrate. Herein, by applying thermal desorption spectroscopy, we found that sulfur loss can be tightly coupled to adsorbed oxygen, as confirmed by observation of SO2 desorption. With annealing MoS2, even under ultrahigh vacuum, oxygen molecules adsorbed on MoS2 assist the sulfur atom in dissociating from MoS2, and thus, defects are formed as the result of SO2 desorption from 200 °C to 600 °C. At higher temperatures (over 800 °C), on the other hand, direct sulfur desorption becomes dominant. This finding can be well explained by combining the morphology investigation enabled by atomic layer deposition at defective sites and optical transitions observed by photoluminescence measurements. Moreover, a preannealing treatment prior to exfoliation was found to be an effective method to remove the adsorbed oxygen, thus preventing defect formation.
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Affiliation(s)
- Shuhong Li
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Tomonori Nishimura
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
| | - Mina Maruyama
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Susumu Okada
- Department of Physics, University of Tsukuba Tsukuba Ibaraki 305-8577 Japan
| | - Kosuke Nagashio
- Department of Materials Engineering, University of Tokyo Tokyo 113-8656 Japan
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5
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Pan Q, Tong Z, Su Y, Zheng Y, Shang L, Tang Y. Flat-Zigzag Interface Design of Chalcogenide Heterostructure toward Ultralow Volume Expansion for High-Performance Potassium Storage. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203485. [PMID: 35962631 DOI: 10.1002/adma.202203485] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 07/18/2022] [Indexed: 06/15/2023]
Abstract
Heterostructure construction of layered metal chalcogenides can boost their alkali-metal storage performance, where the charge transfer kinetics can be promoted by the built-in electric fields. However, these heterostructures usually undergo interface separation due to severe layer expansion, especially for large-size potassium accommodation, resulting in the deconstruction of heterostructures and battery performance fading. Herein, first a stable interface design strategy where two metal chalcogenides with totally different layer-morphologies are stacked to form large K+ transport channels, rendering ultralow interlayer expansion, is presented. As a proof of concept, the flat-zigzag MoS2 /Bi2 S3 heterostructures stacked with zigzag-morphology Bi2 S3 and flat-morphology MoS2 present an ultralow expansion ratio (1.98%) versus MoS2 (9.66%) and Bi2 S3 (9.61%), which deliver an ultrahigh potassium storage capacity of above 600 mAh g-1 and capacity retention of 76% after 500 cycles, together with the built-in electric field of heterostructures. Once the heterostructures are used as an anode for potassium-based dual-ion batteries (K-DIBs), it achieves a superior full-cell capacity of ≈166 mAh g-1 with a capacity retention of 71% after 400 cycles, which is an outstanding performance among the reported K-DIBs. This proposed interface stacking strategy may offer a new way toward stable heterostructure design for metal ions storage and transport applications.
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Affiliation(s)
- Qingguang Pan
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou, 215123, China
| | - Zhaopeng Tong
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuanqiang Su
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongping Zheng
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou, 215123, China
| | - Lin Shang
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- Nano Science and Technology Institute, University of Science and Technology of China, Suzhou, 215123, China
| | - Yongbing Tang
- Advanced Energy Storage Technology Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Key Laboratory of Advanced Materials Processing & Mold, Ministry of Education, Zhengzhou University, Zhengzhou, 450002, China
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Lee S, Lee Y, Ding LP, Lee K, Ding F, Kim K. Atomically Sharp, Closed Bilayer Phosphorene Edges by Self-Passivation. ACS NANO 2022; 16:12822-12830. [PMID: 35904253 DOI: 10.1021/acsnano.2c05014] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Two-dimensional crystals' edge structures not only influence their overall properties but also dictate their formation due to edge-mediated synthesis and etching processes. Edges must be carefully examined because they often display complex, unexpected features at the atomic scale, such as reconstruction, functionalization, and uncontrolled contamination. Here, we examine atomic-scale edge structures and uncover reconstruction behavior in bilayer phosphorene. We use in situ transmission electron microscopy (TEM) of phosphorene/graphene specimens at elevated temperatures to minimize surface contamination and reduce e-beam damage, allowing us to observe intrinsic edge configurations. The bilayer zigzag (ZZ) edge was found to be the most stable edge configuration under e-beam irradiation. Through first-principles calculations and TEM image analysis under various tilting and defocus conditions, we find that bilayer ZZ edges undergo edge reconstruction and so acquire closed, self-passivated edge configurations. The extremely low formation energy of the closed bilayer ZZ edge and its high stability against e-beam irradiation are confirmed by first-principles calculations. Moreover, we fabricate bilayer phosphorene nanoribbons with atomically sharp closed ZZ edges. The identified bilayer ZZ edges will aid in the fundamental understanding of the synthesis, degradation, reconstruction, and applications of phosphorene and related structures.
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Affiliation(s)
- Sol Lee
- Department of Physics, Yonsei University, Seoul 03722, South Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul 03722, South Korea
| | - Yangjin Lee
- Department of Physics, Yonsei University, Seoul 03722, South Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul 03722, South Korea
| | - Li Ping Ding
- Center for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan 44919, South Korea
- Department of Optoelectronic Science & Technology, School of Electronic Information and Artificial Intelligence, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Kihyun Lee
- Department of Physics, Yonsei University, Seoul 03722, South Korea
| | - Feng Ding
- Center for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan 44919, South Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Kwanpyo Kim
- Department of Physics, Yonsei University, Seoul 03722, South Korea
- Center for Nanomedicine, Institute for Basic Science, Seoul 03722, South Korea
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7
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Yang S, Wu J, Wang C, Yan H, Han L, Feng J, Zhang B, Li D, Yu G, Luo B. Molten-droplet-driven growth of MoS 2 flakes with controllable morphology transition for hydrogen evolution reactions. Dalton Trans 2022; 51:13351-13360. [PMID: 35984420 DOI: 10.1039/d2dt02066a] [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 controllable fabrication of two-dimensional transition-metal dichalcogenides (2D TMDs) and a deep understanding of the corresponding process mechanisms are of fundamental importance for their further applications. In this study, the molten-droplet-driven (MDD) growth of MoS2 based on a Na-Mo-O molten-salt chemical vapor deposition (CVD) method is demonstrated via temperature-dependent dispersion and spreading of droplets on a surface, yielding MoS2 flakes with morphology transition from compact triangles to fractal dendrites with the increase in temperature. By building up the dependence between the formed morphologies of grown MoS2 flakes and the corresponding kinetics during successive growth processes, it was found that the wetting-driven force, which is governed by interface free energies (surface tension) of molten droplets, would largely determine the driven movement of the droplet, and then the formation of different morphologies. Finally, based on these MoS2 flakes, a systematic improvement of the hydrogen evolution reaction (HER) was demonstrated in accordance with the evolution of morphologies from compact to fractal. This study presents an important advance in understanding the growth mechanisms related to the molten-salt-assisted CVD fabrication of 2D TMDs and provides a facile method for tailoring the growth and application of 2D TMDs with controllably trimmed morphologies.
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Affiliation(s)
- Shuai Yang
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Jing Wu
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Chao Wang
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Hong Yan
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Luoqiao Han
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Jianmin Feng
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Bo Zhang
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Dejun Li
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
| | - Gui Yu
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China. .,School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Birong Luo
- College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, P. R. China.
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8
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Sui X, Wang H, Liang C, Zhang Q, Bo H, Wu K, Zhu Z, Gong Y, Yue S, Chen H, Shang Q, Mi Y, Gao P, Zhang Y, Meng S, Liu X. Ultrafast Internal Exciton Dissociation through Edge States in MoS 2 Nanosheets with Diffusion Blocking. NANO LETTERS 2022; 22:5651-5658. [PMID: 35786976 DOI: 10.1021/acs.nanolett.1c04987] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Edge states of two-dimensional transition-metal dichalcogenides (TMDCs) are crucial to quantum circuits and optoelectronics. However, their dynamics are pivotal but remain unclear due to the edge states being obscured by their bulk counterparts. Herein, we study the state-resolved transient absorption spectra of ball-milling-produced MoS2 nanosheets with 10 nm lateral size with highly exposed free edges. Electron energy loss spectroscopy and first-principles calculations confirm that the edge states are located in the range from 1.23 to 1.78 eV. Upon above bandgap excitations, excitons populate and diffuse toward the boundary, where the potential gradient blocks excitons and the edge states are formed through interband transitions within 400 fs. With below bandgap excitations, edge states are slowed down to 1.1 ps due to the weakened valence orbital coupling. These results shed light on the fundamental exciton dissociation processes on the boundary of functionalized TMDCs, enabling the ground work for applications in optoelectronics and light-harvesting.
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Affiliation(s)
- Xinyu Sui
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Huimin Wang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
- The Laboratory of Soft Matter Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Cheng Liang
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Qing Zhang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Han Bo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Keming Wu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Zhuoya Zhu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yiyang Gong
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Shuai Yue
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Hailong Chen
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Qiuyu Shang
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
| | - Yang Mi
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Peng Gao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P. R. China
- Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, P. R. China
| | - Yong Zhang
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Sheng Meng
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Xinfeng Liu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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9
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Chen J, Zhou J, Xu W, Wen Y, Liu Y, Warner JH. Atomic-Level Dynamics of Point Vacancies and the Induced Stretched Defects in 2D Monolayer PtSe 2. NANO LETTERS 2022; 22:3289-3297. [PMID: 35389659 DOI: 10.1021/acs.nanolett.1c04275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Monolayer PtSe2 holds great potential in extending 2D devices functionality, but their atomic-level-defect study is still limited. Here, we investigate the atomic structures of lattice imperfections from point to stretched 1D defects in 1T-PtSe2 monolayers, using annular dark-field scanning transmission electron microscopy (ADF-STEM). We show Se vacancies (VSe) have preferential sites with high beam-induced mobility. Diverse divacancies form with paired VSe. We found stretched linear defects triggered by dynamics of VSe that altered strain fields, distinct from the line vacancies in 2H-phase 2D materials. The paired VSe stability and formation possibility of vacancy lines are evaluated by density functional theory. Lower sputtering energy in PtSe2 than that in MoS2 can cause larger possibility of atomic loss compared to diffusion required for creating VSe lines. This provides atomic insights into the defects in 1T-PtSe2 and shows how a deviated 1D structure is embedded in a 2D system without losing atom lines.
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Affiliation(s)
- Jun Chen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jiang Zhou
- Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, Texas 78712, United States
- Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian 116024, China
| | - Wenshuo Xu
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Yi Wen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Yuanyue Liu
- Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, Texas 78712, United States
| | - Jamie H Warner
- Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 East Dean Keeton Street, Austin, Texas 78712, United States
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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10
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Wen Y, Fang S, Coupin M, Lu Y, Ophus C, Kaxiras E, Warner JH. Mapping 1D Confined Electromagnetic Edge States in 2D Monolayer Semiconducting MoS 2 Using 4D-STEM. ACS NANO 2022; 16:6657-6665. [PMID: 35344654 DOI: 10.1021/acsnano.2c01170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Four-dimensional (4D) scanning transmission electron microscopy is used to study the electric fields at the edges of 2D semiconducting monolayer MoS2. Sub-nanometer 1D features in the 2D electric field maps are observed at the outermost region along zigzag edges and also along nanowire MoS-terminated MoS2 edges. Atomic-scale oscillations are detected in the magnitude of the 1D electromagnetic edge state, with spatial variations that depend on the specific periodic edge reconstructions. Electric field reconstructions, along with integrated differential phase contrast reconstructions, reveal the presence of low Z number atoms terminating many of the uniform edges, which are difficult to detect by annular dark field scanning transmission electron microscopy due to its limited dynamic range. Density functional theory calculations support the formation of periodic 1D edge states and also show that enhancement of the electric field magnitude can occur for some edge terminations. The experimentally observed electric fields at the edges are attributed to the absence of an opposing electric field from a nearest neighbor atom when the electron beam propagates through the 2D monolayer and interacts. These results show the potential of 4D-STEM to map the atomic scale structure and fluctuations of electric fields around edge atoms with different bonding states than bulk atoms in 2D materials, beyond conventional imaging.
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Affiliation(s)
- Yi Wen
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Shiang Fang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Matthew Coupin
- Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 E Dean Keeton Street, Austin, Texas 78712, United States
| | - Yang Lu
- Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Colin Ophus
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Efthimios Kaxiras
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Jamie H Warner
- Materials Graduate Program, Texas Materials Institute, The University of Texas at Austin, 204 E Dean Keeton Street, Austin, Texas 78712, United States
- Walker Department of Mechanical Engineering, The University of Texas at Austin, 204 E Dean Keeton Street, Austin, Texas 78712, United States
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11
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Ouyang Y, Zhou Y, Zhang Y, Li Q, Wang J. Double-edged roles of intrinsic defects in two-dimensional MoS2. TRENDS IN CHEMISTRY 2022. [DOI: 10.1016/j.trechm.2022.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Tseng YT, Lu LS, Shen FC, Wang CH, Sung HY, Chang WH, Wu WW. In Situ Atomic-Scale Observation of Monolayer MoS 2 Devices under High-Voltage Biasing via Transmission Electron Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106411. [PMID: 34995002 DOI: 10.1002/smll.202106411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/27/2021] [Indexed: 06/14/2023]
Abstract
2D materials have great potential for not only device scaling but also various applications. To prompt the development of 2D electronics and optoelectronics, a better understanding of the limitation of materials is essential. Material failure caused by bias can lead to variations in device behavior and even electrical breakdown. In this study, the structural evolution of monolayer MoS2 with high bias is revealed via in situ transmission electron microscopy at the atomic scale. The biasing process is recorded and studied with the aid of aberration-corrected scanning transmission electron microscopy. The effects of electron beam irradiation and biasing are also discussed through the combination of experiments and theory. It is found that the Mo nanoclusters result from disintegration of MoS2 and sulfur depletion, which are induced by Joule heating. The thermal stress can also damage the MoS2 layer and form long cracks in both in situ and ex situ biasing cases. Investigation of the results obtained with different applied voltages helps to further verify the mechanism of evolution and provide a comprehensive study of the function of biasing.
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Affiliation(s)
- Yi-Tang Tseng
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
| | - Li-Syuan Lu
- Department of Electrophysics, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
| | - Fang-Chun Shen
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
| | - Che-Hung Wang
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
| | - Hsin-Ya Sung
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
| | - Wen-Hao Chang
- Department of Electrophysics, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
- Research Center for Applied Sciences, Academia Sinica, No. 128, Sec. 2, Academia Rd., Nangang Dist., Taipei City, 11529, Taiwan
| | - Wen-Wei Wu
- Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
- Center for the Intelligent Semiconductor Nano-system Technology Research, National Yang Ming Chiao Tung University, No. 1001, University Rd., East Dist., Hsinchu City, 30010, Taiwan
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13
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Yoon A, Kim JH, Lee Z. Elucidation of Novel Potassium-Mediated Oxidation and Etching of Two-Dimensional Transition Metal Dichalcogenides. ACS APPLIED MATERIALS & INTERFACES 2021; 13:49163-49171. [PMID: 34632769 DOI: 10.1021/acsami.1c13607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Preparation of edge-rich two-dimensional (2D) transition metal dichalocogenides (TMDs) has been actively investigated with the aim to improve their electrical and catalytic properties. Here, we elucidate the role of potassium ions in oxidation of TMDs and suggest a consequent novel anisotropic etching mechanism driven by self-running oxide droplets. We discover that potassium-mediated oxidation of MoS2 leads to the formation of K-intercalated hexagonal-phase molybdenum oxides (h-KxMoO3), whereas orthorhombic-phase oxides are formed in the absence of potassium ions. Metastable h-KxMoO3 appears to have decomposed into oxide droplets at higher temperature. Self-running of the oxide droplets leads to layer-by-layer anisotropic etching of MoS2 along the armchair direction. The motion of the droplets appears to be triggered by the surface energy instability between the oxide droplets and the underlying MoS2 layer. This study opens new possibilities to design and manufacture novel edge-rich 2D TMDs that do not follow the equilibrium Wulff shape by modulating their oxidation with the assistance of alkali metals and also offers fundamental insights into the interactions between nanodroplets and 2D materials toward edge engineering.
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Affiliation(s)
- Aram Yoon
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jung Hwa Kim
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
| | - Zonghoon Lee
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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14
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Ta HQ, Mendes RG, Liu Y, Yang X, Luo J, Bachmatiuk A, Gemming T, Zeng M, Fu L, Liu L, Rümmeli MH. In Situ Fabrication of Freestanding Single-Atom-Thick 2D Metal/Metallene and 2D Metal/ Metallene Oxide Membranes: Recent Developments. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100619. [PMID: 34459155 PMCID: PMC8529443 DOI: 10.1002/advs.202100619] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/23/2021] [Indexed: 05/13/2023]
Abstract
In recent years, two-dimensional (2D) materials have attracted a lot of research interest as they exhibit several fascinating properties. However, outside of 2D materials derived from van der Waals layered bulk materials only a few other such materials are realized, and it remains difficult to confirm their 2D freestanding structure. Despite that, many metals are predicted to exist as 2D systems. In this review, the authors summarize the recent progress made in the synthesis and characterization of these 2D metals, so called metallenes, and their oxide forms, metallene oxides as free standing 2D structures formed in situ through the use of transmission electron microscopy (TEM) and scanning TEM (STEM) to synthesize these materials. Two primary approaches for forming freestanding monoatomic metallic membranes are identified. In the first, graphene pores as a means to suspend the metallene or metallene oxide and in the second, electron-beam sputtering for the selective etching of metal alloys or thick complex initial materials is employed to obtain freestanding single-atom-thick 2D metal. The data show a growing number of 2D metals/metallenes and 2D metal/ metallene oxides having been confirmed and point to a bright future for further discoveries of these 2D materials.
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Affiliation(s)
- Huy Q. Ta
- Soochow Institute for Energy and Materials InnovationsCollege of EnergyCollaborative Innovation Center of SuzhouNano Science and TechnologyKey Laboratory of Advanced Carbon MaterialsWearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou215006China
- Institute for Complex MaterialsIFW DresdenP.O. Box D‐01171DresdenGermany
| | - Rafael G. Mendes
- Institute for Complex MaterialsIFW DresdenP.O. Box D‐01171DresdenGermany
| | - Yu Liu
- Soochow Institute for Energy and Materials InnovationsCollege of EnergyCollaborative Innovation Center of SuzhouNano Science and TechnologyKey Laboratory of Advanced Carbon MaterialsWearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou215006China
| | - Xiaoqin Yang
- Soochow Institute for Energy and Materials InnovationsCollege of EnergyCollaborative Innovation Center of SuzhouNano Science and TechnologyKey Laboratory of Advanced Carbon MaterialsWearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou215006China
- School of Energy and Power EngineeringXi'an Jiaotong UniversityNo. 28, Xianning West RoadXi'anShaanxi710049China
| | - Jingping Luo
- School of Energy and Power EngineeringXi'an Jiaotong UniversityNo. 28, Xianning West RoadXi'anShaanxi710049China
| | - Alicja Bachmatiuk
- Material Science & Engineering CenterŁukasiewicz Research Network – PORT Polish Center for Technology DevelopmentUl. Stabłowicka 147Wrocław54‐066Poland
| | - Thomas Gemming
- Institute for Complex MaterialsIFW DresdenP.O. Box D‐01171DresdenGermany
| | - Mengqi Zeng
- College of Chemistry and Molecular ScienceWuhan UniversityWuhan430072China
| | - Lei Fu
- College of Chemistry and Molecular ScienceWuhan UniversityWuhan430072China
| | - Lijun Liu
- School of Energy and Power EngineeringXi'an Jiaotong UniversityNo. 28, Xianning West RoadXi'anShaanxi710049China
| | - Mark H. Rümmeli
- Soochow Institute for Energy and Materials InnovationsCollege of EnergyCollaborative Innovation Center of SuzhouNano Science and TechnologyKey Laboratory of Advanced Carbon MaterialsWearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou215006China
- Institute for Complex MaterialsIFW DresdenP.O. Box D‐01171DresdenGermany
- Centre of Polymer and Carbon MaterialsPolish Academy of SciencesM. Curie‐Sklodowskiej 34Zabrze41‐819Poland
- Center for Energy and Environmental TechnologiesVSB‐Technical University of Ostrava17. Listopadu 15Ostrava708 33Czech Republic
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15
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Probing atom dynamics of excited Co-Mo-S nanocrystals in 3D. Nat Commun 2021; 12:5007. [PMID: 34408156 PMCID: PMC8373969 DOI: 10.1038/s41467-021-24857-4] [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: 01/14/2021] [Accepted: 07/05/2021] [Indexed: 12/01/2022] Open
Abstract
Advances in electron microscopy have enabled visualizations of the three-dimensional (3D) atom arrangements in nano-scale objects. The observations are, however, prone to electron-beam-induced object alterations, so tracking of single atoms in space and time becomes key to unravel inherent structures and properties. Here, we introduce an analytical approach to quantitatively account for atom dynamics in 3D atomic-resolution imaging. The approach is showcased for a Co-Mo-S nanocrystal by analysis of time-resolved in-line holograms achieving ~1.5 Å resolution in 3D. The analysis reveals a decay of phase image contrast towards the nanocrystal edges and meta-stable edge motifs with crystallographic dependence. These findings are explained by beam-stimulated vibrations that exceed Debye-Waller factors and cause chemical transformations at catalytically relevant edges. This ability to simultaneously probe atom vibrations and displacements enables a recovery of the pristine Co-Mo-S structure and establishes, in turn, a foundation to understand heterogeneous chemical functionality of nanostructures, surfaces and molecules. The authors introduce an analytical approach for quantitative analysis of 3D atom dynamics during electron microscopy. They image a Co-Mo-S nanocrystal with 1.5 Å resolution, and observe chemical transformations caused by beam-stimulated vibrations.
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16
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Yao F, Xiao Z, Qiao J, Ji W, Xie RJ, Jin C. In situ TEM study of edge reconstruction and evolution in monolayer black phosphorus. NANOSCALE 2021; 13:4133-4139. [PMID: 33575688 DOI: 10.1039/d0nr08798j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
As symmetry-breaking interfaces, edges inevitably influence material properties, particularly for low-dimensional materials such as two-dimensional (2D) graphene and black phosphorus (BP). Hence, exploiting pristine edge structures and the associated edge reconstruction is important. In this study, we revealed edge reconstruction and evolution in monolayer BP (ML-BP) via in situ high-resolution transmission electron microscopy. Under our typical experimental conditions, spontaneous edge reconstruction occurred in all types of as-prepared edges that include zigzag, Klein zigzag, diagonal, and Klein diagonal edges. Reconstruction induces a periodic variation of the bond length and bond angles of edge atoms: an out-of-plane bending for zigzag and diagonal edge atoms and a dimerization for two neighboring edge atoms on the Klein edge, respectively. Surface atom diffusion can also induce edge structural evolution as evidenced by the atomic scale dynamics captured for the zigzag edge. Experimentally resolved edge configurations and reconstruction were further corroborated by ab initio first-principles calculations. This study explores the understanding of the edge stability in 2D BP materials and may provide routes for precisely controlled edge structure engineering.
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Affiliation(s)
- Fenfa Yao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen, Fujian 361005, China. and State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
| | - Zhangru Xiao
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
| | - Jingsi Qiao
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Wei Ji
- Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China
| | - Rong-Jun Xie
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen, Fujian 361005, China.
| | - Chuanhong Jin
- State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China. and Hunan Institute of Advanced Sensing and Information Technology, Xiangtan University, Xiangtan, Hunan 411105, China
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17
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Chowdhury T, Sadler EC, Kempa TJ. Progress and Prospects in Transition-Metal Dichalcogenide Research Beyond 2D. Chem Rev 2020; 120:12563-12591. [DOI: 10.1021/acs.chemrev.0c00505] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Tomojit Chowdhury
- Department of Chemistry, Johns Hopkins University, Baltimore 21218, United States
| | - Erick C. Sadler
- Department of Chemistry, Johns Hopkins University, Baltimore 21218, United States
| | - Thomas J. Kempa
- Department of Chemistry, Johns Hopkins University, Baltimore 21218, United States
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore 21218, United States
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18
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Deng X, Li Z, Yang J. One-Dimensional Magnetic Order Stabilized in Edge-Reconstructed MoS 2 Nanoribbon via Bias Voltage. J Phys Chem Lett 2020; 11:7531-7535. [PMID: 32812762 DOI: 10.1021/acs.jpclett.0c02302] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Low-dimensional nanostructures are expected to play an important role in spintronics. However, in low-dimensional systems, thermal fluctuations become more significant, which makes long-range magnetic ordering thermodynamically unfavorable. For example, as predicted by the Ising model, 1D magnetic order cannot survive, even at an arbitrary low finite temperature. In this study, utilizing a nanoproximity effect, we design a MoS2 nanoribbon material to stabilize 1D magnetic order without requiring the explicit application of an external magnetic field. The designed MoS2 nanoribbon has a new edge-reconstruction pattern, which is much more stable than previously reported structures. As a novel electronic property, one edge is nonmagnetic but conductive, and the opposite edge contains a magnetic moment in the predicted reconstruction pattern. Therefore, a bias voltage can drive a current along the former edge, which then generates a magnetic field at the opposite edge to stabilize the 1D magnetic order there. This result opens a new avenue to realize the integrated electrical control of magnetism.
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Affiliation(s)
- Xiaohui Deng
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, Hunan 421002, China
| | - Zhenyu Li
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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19
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Transition metal dichalcogenide metamaterials with atomic precision. Nat Commun 2020; 11:4604. [PMID: 32929093 PMCID: PMC7490684 DOI: 10.1038/s41467-020-18428-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 08/17/2020] [Indexed: 11/09/2022] Open
Abstract
The ability to extract materials just a few atoms thick has led to the discoveries of graphene, monolayer transition metal dichalcogenides (TMDs), and other important two-dimensional materials. The next step in promoting the understanding and utility of flatland physics is to study the one-dimensional edges of these two-dimensional materials as well as to control the edge-plane ratio. Edges typically exhibit properties that are unique and distinctly different from those of planes and bulk. Thus, controlling the edges would allow the design of materials with combined edge-plane-bulk characteristics and tailored properties, that is, TMD metamaterials. However, the enabling technology to explore such metamaterials with high precision has not yet been developed. Here we report a facile and controllable anisotropic wet etching method that allows scalable fabrication of TMD metamaterials with atomic precision. We show that TMDs can be etched along certain crystallographic axes, such that the obtained edges are nearly atomically sharp and exclusively zigzag-terminated. This results in hexagonal nanostructures of predefined order and complexity, including few-nanometer-thin nanoribbons and nanojunctions. Thus, this method enables future studies of a broad range of TMD metamaterials through atomically precise control of the structure. Here, the authors devise a scalable method, based on anisotropic wet etching, to fabricate hexagonally shaped transition metal dichalcogenide nanostructures with smooth edges, which may serve as metamaterials with tailored optical properties.
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20
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Wang W, Shu H, Zhou D, Wang J, Chen X. Ultrafast nucleation and growth of high-quality monolayer MoSe 2 crystals via vapor-liquid-solid mechanism. NANOTECHNOLOGY 2020; 31:335601. [PMID: 32365342 DOI: 10.1088/1361-6528/ab8fe2] [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
The controlled production of two-dimensional atomically thin transition metal dichalcogenides (TMDs) is fundamentally important for their device applications. However, the synthesis of large-area and high-quality TMD monolayers remains a challenge due to the lack of sufficient understanding of growth mechanisms, especially for the chemical vapor deposition (CVD). Here we report molten-salt assisted CVD growth of highly crystalline MoSe2 monolayers via a novel vapor-liquid-solid (VLS) mechanism. Our results show that the growth rate of the VLS-grown monolayer MoSe2 is about 40 times faster than that of MoSe2 grown via the vapor-solid (VS) mechanism, which makes the fabrication of 100 μm domains for ∼2 min and a uniform monolayer film within 5 min. The ultrafast growth of monolayer MoSe2 crystals benefits from the synergic effect of one-dimensional VLS growth and two-dimensional VS edge expansion. Moreover, these MoSe2 monolayers exhibit high crystal quality and enhanced photoluminescence due to efficient Se-vacancy repairing by the doping of halogen atoms. These findings provide a new understanding of MoSe2 growth and open up an opportunity for the rapid synthesis of high-quality TMD monolayers and heterostructures.
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Affiliation(s)
- Wenfeng Wang
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, People's Republic of China
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21
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Huang L, Thi QH, Zheng F, Chen X, Chu YW, Lee CS, Zhao J, Ly TH. Catalyzed Kinetic Growth in Two-Dimensional MoS2. J Am Chem Soc 2020; 142:13130-13135. [DOI: 10.1021/jacs.0c05057] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lingli Huang
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen, China
| | - Quoc Huy Thi
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen, China
| | - Fangyuan Zheng
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen, China
| | - Xin Chen
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
| | - Yee Wa Chu
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
| | - Chun-Sing Lee
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
| | - Jiong Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
- Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen, China
| | - Thuc Hue Ly
- Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen, China
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22
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Ghatak K, Kang KN, Yang EH, Datta D. Controlled edge dependent stacking of WS 2-WS 2 Homo- and WS 2-WSe 2 Hetero-structures: A Computational Study. Sci Rep 2020; 10:1648. [PMID: 32015400 PMCID: PMC6997452 DOI: 10.1038/s41598-020-58149-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/03/2020] [Indexed: 11/09/2022] Open
Abstract
Transition Metal Dichalcogenides (TMDs) are one of the most studied two-dimensional materials in the last 5-10 years due to their extremely interesting layer dependent properties. Despite the presence of vast research work on TMDs, the complex relation between the electro-chemical and physical properties make them the subject of further research. Our main objective is to provide a better insight into the electronic structure of TMDs. This will help us better understand the stability of the bilayer post growth homo/hetero products based on the various edge-termination, and different stacking of the two layers. In this regard, two Tungsten (W) based non-periodic chalcogenide flakes (sulfides and selenides) were considered. An in-depth analysis of their different edge termination and stacking arrangement was performed via Density Functional Theory method using VASP software. Our finding indicates the preference of chalcogenide (c-) terminated structures over the metal (m-) terminated structures for both homo and heterobilayers, and thus strongly suggests the nonexistence of the m-terminated TMDs bilayer products.
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Affiliation(s)
- Kamalika Ghatak
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ, 07103, USA
| | - Kyung Nam Kang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Eui-Hyeok Yang
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA.
| | - Dibakar Datta
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ, 07103, USA.
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23
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Gerkman MA, Lee JK, Li X, Zhang Q, Windley M, Fonseca MV, Lu Y, Warner JH, Han GGD. Direct Imaging of Individual Molecular Binding to Clean Nanopore Edges in 2D Monolayer MoS 2. ACS NANO 2020; 14:153-165. [PMID: 31747249 DOI: 10.1021/acsnano.9b06061] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We use annular dark-field scanning transmission electron microscopy (ADF-STEM) to study how solution-deposited molecules bind to the edges and surface regions around nanopores in MoS2 monolayers. Nanopores with clean atomically flat edges and controllable mean diameter were generated by time-dependent large-area electron beam exposure during an in situ heating process, ready for subsequent molecular attachment. An organic molecule was designed to have a dithiolane end group that binds to Mo-terminated sites and a ligand structure that incorporates a single transition metal atom (Pt) marker for ADF-STEM detection. Pt atoms were used to track molecular binding around zigzag edges of MoS2 and to predict the orientations and conformations of molecules upon binding. We found that the molecules preferred to reside on the surface of the MoS2, pointing inward when attaching to the edge, rather than dangling out from the edge into free space, which is attributed to van der Waals interactions between the aromatic core of the molecule and the MoS2 basal planes. These results help us understand the way solution-deposited single molecules attach to free-standing edges of 2D crystals and the influence of van der Waals forces in guiding molecular binding.
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Affiliation(s)
- Mihael A Gerkman
- Department of Chemistry , Brandeis University , 415 South Street , Waltham , Massachusetts 02453 , United States
| | - Ja Kyung Lee
- Department of Materials , University of Oxford , 16 Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Xiang Li
- Department of Chemistry , Brandeis University , 415 South Street , Waltham , Massachusetts 02453 , United States
| | - Qianyang Zhang
- Department of Materials , University of Oxford , 16 Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Maurice Windley
- Department of Chemistry , Brandeis University , 415 South Street , Waltham , Massachusetts 02453 , United States
| | - Maria V Fonseca
- Department of Chemistry , Brandeis University , 415 South Street , Waltham , Massachusetts 02453 , United States
| | - Yang Lu
- Department of Materials , University of Oxford , 16 Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Jamie H Warner
- Department of Materials , University of Oxford , 16 Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Grace G D Han
- Department of Chemistry , Brandeis University , 415 South Street , Waltham , Massachusetts 02453 , United States
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24
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Gao L, Liao Q, Zhang X, Liu X, Gu L, Liu B, Du J, Ou Y, Xiao J, Kang Z, Zhang Z, Zhang Y. Defect-Engineered Atomically Thin MoS 2 Homogeneous Electronics for Logic Inverters. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906646. [PMID: 31743525 DOI: 10.1002/adma.201906646] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Ultrathin molybdenum disulfide (MoS2 ) presents ideal properties for building next-generation atomically thin circuitry. However, it is difficult to construct logic units of MoS2 monolayer using traditional silicon-based doping schemes, such as atomic substitution and ion implantation, as they cause lattice disruption and doping instability. An accurate and feasible electronic structure modulation strategy from defect engineering is proposed to construct homogeneous electronics for MoS2 monolayer logic inverters. By utilizing the energy-matched electron induction of the solution process, numerous pure and lattice-stable monosulfur vacancies (Vmonos ) are introduced to modulate the electronic structure of monolayer MoS2 via a shallow trapping effect. The resulting modulation effectively reduces the electronic concentration of MoS2 and improves the work function by 100 meV. Under modulation of Vmonos , an atomically thin homogenous monolayer MoS2 logic inverter with a voltage gain of 4 is successfully constructed. A brand-new and practical design route of defect modulation for 2D-based circuit development is provided.
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Affiliation(s)
- Li Gao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Qingliang Liao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiankun Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Xiaozhi Liu
- Collaborative Innovation Center of Quantum Matter, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Lin Gu
- Collaborative Innovation Center of Quantum Matter, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Baishan Liu
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Junli Du
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yang Ou
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Jiankun Xiao
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhuo Kang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zheng Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Yue Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing, 100083, P. R. China
- State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
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Tai KL, Huang CW, Cai RF, Huang GM, Tseng YT, Chen J, Wu WW. Atomic-Scale Fabrication of In-Plane Heterojunctions of Few-Layer MoS 2 via In Situ Scanning Transmission Electron Microscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1905516. [PMID: 31825564 DOI: 10.1002/smll.201905516] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/14/2019] [Indexed: 06/10/2023]
Abstract
Layered MoS2 is a prospective candidate for use in energy harvesting, valleytronics, and nanoelectronics. Its properties strongly related to its stacking configuration and the number of layers. Due to its atomically thin nature, understanding the atomic-level and structural modifications of 2D transition metal dichalcogenides is still underdeveloped, particularly the spatial control and selective precision. Therefore, the development of nanofabrication techniques is essential. Here, an atomic-scale approach used to sculpt 2D few-layer MoS2 into lateral heterojunctions via in situ scanning/transmission electron microscopy (STEM/TEM) is developed. The dynamic evolution is tracked using ultrafast and high-resolution filming equipment. The assembly behaviors inherent to few-layer 2D-materials are observed during the process and included the following: scrolling, folding, etching, and restructuring. Atomic resolution STEM is employed to identify the layer variation and stacking sequence for this new 2D-architecture. Subsequent energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy analyses are performed to corroborate the elemental distribution. This sculpting technique that is established allows for the formation of sub-10 nm features, produces diverse nanostructures, and preserves the crystallinity of the material. The lateral heterointerfaces created in this study also pave the way for the design of quantum-relevant geometries, flexible optoelectronics, and energy storage devices.
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Affiliation(s)
- Kuo-Lun Tai
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Chun-Wei Huang
- Material and Chemical Research Laboratories, Nanotechnology Research Center, Industrial Technology Research Institute, Hsinchu, 310, Taiwan
| | - Ren-Fong Cai
- Material and Chemical Research Laboratories, Nanotechnology Research Center, Industrial Technology Research Institute, Hsinchu, 310, Taiwan
| | - Guan-Min Huang
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Yi-Tang Tseng
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
| | - Jun Chen
- Department of Materials, University of Oxford, OX1 2JD, Oxford, UK
| | - Wen-Wei Wu
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu City, 300, Taiwan
- Center for the Intelligent Semiconductor Nano-system Technology Research, National Chiao Tung University, Hsinchu, 300, Taiwan
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26
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Zhao P, Wang R, Lien DH, Zhao Y, Kim H, Cho J, Ahn GH, Javey A. Scanning Probe Lithography Patterning of Monolayer Semiconductors and Application in Quantifying Edge Recombination. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900136. [PMID: 31550404 DOI: 10.1002/adma.201900136] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 09/06/2019] [Indexed: 06/10/2023]
Abstract
Scanning probe lithography is used to directly pattern monolayer transition metal dichalcogenides (TMDs) without the use of a sacrificial resist. Using an atomic-force microscope, a negatively biased tip is brought close to the TMD surface. By inducing a water bridge between the tip and the TMD surface, controllable oxidation is achieved at the sub-100 nm resolution. The oxidized flake is then submerged into water for selective oxide removal which leads to controllable patterning. In addition, by changing the oxidation time, thickness tunable patterning of multilayer TMDs is demonstrated. This resist-less process results in exposed edges, overcoming a barrier in traditional resist-based lithography and dry etch where polymeric byproduct layers are often formed at the edges. By patterning monolayers into geometric patterns of different dimensions and measuring the effective carrier lifetime, the non-radiative recombination velocity due to edge defects is extracted. Using this patterning technique, it is shown that selenide TMDs exhibit lower edge recombination velocity as compared to sulfide TMDs. The utility of scanning probe lithography towards understanding material-dependent edge recombination losses without significantly normalizing edge behaviors due to heavy defect generation, while allowing for eventual exploration of edge passivation schemes is highlighted, which is of profound interest for nanoscale electronics and optoelectronics.
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Affiliation(s)
- Peida Zhao
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ruixuan Wang
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
| | - Der-Hsien Lien
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Yingbo Zhao
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Hyungjin Kim
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Joy Cho
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Geun Ho Ahn
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ali Javey
- Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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27
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Lin TY, Lee SK, Huang GM, Huang CW, Tai KL, Huang CY, Lo YC, Wu WW. Electron Beam Irradiation-Induced Deoxidation and Atomic Flattening on the Copper Surface. ACS APPLIED MATERIALS & INTERFACES 2019; 11:40909-40915. [PMID: 31573187 DOI: 10.1021/acsami.9b14529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electron beam (e-beam) has been developed for nanomaterial observation and moreover to induce structural evolutions in atomic scale. In this work, we demonstrate the deoxidation of cuprous oxide (Cu2O) and the formation of an atomically flat surface on a Cu nanowire by e-beam irradiation. To develop e-beam irradiation applications, the relation between e-beam radiation and the atomic surface is significant. Through the density functional theory simulation of atomic sputtering, an obvious disparity in the sputtering threshold has been found under different structural conditions, which leads to different structural evolutions. Both surface deoxidation and atomic surface flattening reactions have been identified as self-limiting and irreversible processes via in situ transmission electron microscope observation. Under e-beam irradiation, the dynamic mechanism of atomic surface flattening is driven by the convergence of total surface energy and confirmed by climbing-image nudged elastic band (ci-NEB) calculations. With precise control, e-beam irradiation reveals enormous potentials in atomic surface engineering.
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Affiliation(s)
- Ting-Yi Lin
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Shih-Kuang Lee
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Guan-Min Huang
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Chun-Wei Huang
- Material and Chemical Research Laboratories, Nanotechnology Research Center , Industrial Technology Research Institute , 195, Sec. 4, Chung Hsing Road , Chutung, Hsinchu 31040 , Taiwan
| | - Kuo-Lun Tai
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Chih-Yang Huang
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Yu-Chieh Lo
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
| | - Wen-Wei Wu
- Department of Materials Science and Engineering , National Chiao Tung University , 1001 University Road , Hsinchu 30010 , Taiwan
- Center for the Semiconductor Technology Research , National Chiao Tung University , Hsinchu 30010 , Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters , National Tsing Hua University , Hsinchu 30013 , Taiwan
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28
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Ke JA, Garaj S, Gradečak S. Nanopores in 2D MoS 2: Defect-Mediated Formation and Density Modulation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:26228-26234. [PMID: 31305058 DOI: 10.1021/acsami.9b03531] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Oxidation is a scalable process for introducing nanopores in two-dimensional transitional metal dichalcogenides (TMDs) for membrane applications. The nanopore density is determined by the areal density of their nucleation sites; understanding the nature of the defects and their control would enable tailoring of TMD membranes for targeted applications. In this work, we show that the nanopore distribution is dramatically different in strained and unstrained MoS2 crystals. We correlate this spatial distribution to the underlying arrangement of dislocations in MoS2 crystals, in contrast to previously suggested sulfur vacancies. To control the nucleation density of MoS2 nanopores, we demonstrate that the pore density can be modulated by electron beam exposure prior to the nanopore formation. Raman analysis of electron beam-exposed samples indicates that hydrocarbon adsorption activates defect species other than dislocations, which significantly enhances the nanopore density in MoS2.
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Affiliation(s)
- Jian-An Ke
- Department of Materials Science and Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Slaven Garaj
- Department of Physics , National University of Singapore , Singapore 117551 , Singapore
- Centre of Advanced 2D Materials , National University of Singapore , Singapore 117546 , Singapore
| | - Silvija Gradečak
- Department of Materials Science and Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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29
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Li JH, Guo YD, Zeng HL, Mou XY, Yan XH. Edge-modulated dual spin-filter effect in zigzag-shaped buckling Ag 2S nanoribbons. Phys Chem Chem Phys 2019; 21:15623-15629. [PMID: 31268445 DOI: 10.1039/c9cp02521a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unlike MoS2, single-layered Ag2S nanoribbons (Ag2SNRs) exhibit a nonmetal-shrouded and a zigzag-shaped buckling structure and possess two distinct edges, S- or Ag-terminated ones. By performing first principle calculations, the spin-dependent electron transport of Ag2SNRs in a ferromagnetic state has been investigated. It is found that the SS- and AgAg-terminated Ag2SNRs exhibit semi-metallic characteristics, but with opposite spin-polarized directions. And AgS-terminated ones show metallic characteristics, but with completely spin-unpolarized transmission. That is to say, all three states, i.e., spin up polarized, spin down polarized and spin unpolarized ones, could be achieved by modulating the edge geometry. Further analysis shows that, the spatial separation on edges of the energy states with different spins around EF is responsible for the switch in the three states. The system could operate as a dual spin-filter, and the direction of the spin polarization can be switched by the edge morphology. Furthermore, calculations show that such a phenomenon is robust to the width of the ribbon and strain, showing great application potential.
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Affiliation(s)
- Jian-Hua Li
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
| | - Yan-Dong Guo
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China. and College of Natural Science, Nanjing University of Posts and Telecommunications, Nanjing 210046, China and Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, China and New Energy Technology Engineering Laboratory of Jiangsu Province, Nanjing, 210023, Jiangsu, China
| | - Hong-Li Zeng
- College of Natural Science, Nanjing University of Posts and Telecommunications, Nanjing 210046, China and Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, China
| | - Xin-Yi Mou
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
| | - Xiao-Hong Yan
- College of Electronic and Optical Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210023, China. and Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, China and College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China and School of Material Science and Engineering, Jiangsu University, Zhenjiang, 212013, China
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30
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Kondekar N, Boebinger MG, Tian M, Kirmani MH, McDowell MT. The Effect of Nickel on MoS 2 Growth Revealed with in Situ Transmission Electron Microscopy. ACS NANO 2019; 13:7117-7126. [PMID: 31117371 DOI: 10.1021/acsnano.9b02528] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
MoS2 has important applications in (electro)catalysis and as a semiconductor for electronic devices. Other chemical species are commonly added to MoS2 to increase catalytic activity or to alter electronic properties through substitutional or adsorption-based doping. While groundbreaking work has been devoted to determining the atomic-scale structure of MoS2 and other layered transition-metal dichalcogenides (TMDCs), there is a lack of understanding of the dynamic processes that govern the evolution of these materials during synthesis. Here, in situ transmission electron microscopy (TEM) heating, in combination with larger length scale ex situ experiments, is used to investigate the effects of added Ni on the growth of MoS2 during the thermolysis of the solid-state (NH4)2MoS4 precursor. Low concentrations of Ni are observed to cause significant differences in the MoS2 crystallization and growth process, leading to an increase in MoS2 crystal size. This is likely a result of the altered mobility of interfaces between crystals during growth. These findings demonstrate the important role of additional elements in controlling the evolution of TMDCs during synthesis, which should be considered when designing these materials for a variety of applications.
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Affiliation(s)
- Neha Kondekar
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Matthew G Boebinger
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Mengkun Tian
- Institute for Electronics and Nanotechnology, Materials Characterization Facility , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Mohammad Hamza Kirmani
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Matthew T McDowell
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
- G. W. Woodruff School of Mechanical Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
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31
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Hwang YH, Yun WS, Cha GB, Hong SC, Han SW. Thermally driven homonuclear-stacking phase of MoS 2 through desulfurization. NANOSCALE 2019; 11:11138-11144. [PMID: 31107488 DOI: 10.1039/c9nr01369e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Engineering phase transitions or finding new polymorphs offers tremendous opportunities for developing functional materials. We reveal that the thermally driven desulfurization of single-crystalline MoS2 samples improves transport properties by reducing the band gap and further induces metallization. Semi-desulfurization, i.e., removal of the topmost S layer, results in the placement of the exposed Mo layers directly on top of the following sub-layers, together with the bottom S layer of the top layer. This homonuclear (AA) stacking derived from the AA' stacking of the hexagonal (2H) phase is retained even after further desulfurization of the remaining bottom S layer, i.e., full desulfurization of the top layer. Our findings fundamentally explain why the 2H phase of TMDs is characterized by AA' stacking.
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Affiliation(s)
- Young Hun Hwang
- Department of Physics and Energy Harvest-Storage Research Center (EHSRC), University of Ulsan, Ulsan 44610, Republic of Korea.
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32
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Cortés N, Ávalos-Ovando O, Rosales L, Orellana PA, Ulloa SE. Tunable Spin-Polarized Edge Currents in Proximitized Transition Metal Dichalcogenides. PHYSICAL REVIEW LETTERS 2019; 122:086401. [PMID: 30932605 DOI: 10.1103/physrevlett.122.086401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/05/2018] [Indexed: 06/09/2023]
Abstract
We explore proximity-induced ferromagnetism on transition metal dichalcogenides (TMDs), focusing on molybdenum ditelluride ribbons with zigzag edges, deposited on ferromagnetic europium oxide (EuO). A tight-binding model incorporates exchange and Rashba fields induced by proximity to EuO or similar substrates. For in-gap Fermi levels, electronic modes in the nanoribbon are localized along the edges, acting as one-dimensional (1D) conducting channels with tunable spin-polarized currents. TMDs on magnetic substrates can become very useful in spintronics, providing versatile platforms to study the proximity effects and electronic interactions in complex 1D systems.
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Affiliation(s)
- Natalia Cortés
- Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110V, Valparaíso, Chile
- Department of Physics and Astronomy, and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701-2979, USA
| | - O Ávalos-Ovando
- Department of Physics and Astronomy, and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701-2979, USA
| | - L Rosales
- Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110V, Valparaíso, Chile
| | - P A Orellana
- Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110V, Valparaíso, Chile
| | - S E Ulloa
- Department of Physics and Astronomy, and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701-2979, USA
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33
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Chen J, Zhou S, Wen Y, Ryu GH, Allen C, Lu Y, Kirkland AI, Warner JH. In situ high temperature atomic level dynamics of large inversion domain formations in monolayer MoS 2. NANOSCALE 2019; 11:1901-1913. [PMID: 30644498 DOI: 10.1039/c8nr08821g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Here we study the high-temperature formation and dynamics of large inversion domains (IDs) that form in monolayer MoS2 using atomic-resolution annular dark-field scanning transmission electron microscopy (ADF-STEM) with an in situ heating stage. We use temperatures above 700 °C to thermally activate rapid S vacancy migration and this leads to a formation mechanism of IDs that differs from the one at room temperature, where S vacancy migration is limited. We show that at high temperatures the formation of IDs occurs from intersected networks of long S vacancy line defects, whose strain fields are non-orthogonal and trigger large scale atomic reconstructions. Once formed, the IDs are influenced by the dynamic behaviour of nearby line defects and voids. With Mo and S atoms undergoing movement, the two types of ID grain boundaries can shift to allow further expansion of the ID area along the adjoining line defects. We reveal that IDs serve as metastable configurations between line defect rearrangements and eventual void formation under electron beam irradiation during heating. The formation of voids near to the IDs causes them to revert back to pristine lattice, which has the effect of restricting the ID domain size to a certain range (e.g. 3-5 nm in our observation) instead of continuously enlarging. This study provides insights into how the MoS2 IDs form and evolve at high temperature and can benefit the tailoring of electronic properties of two dimensional materials by structural manipulation.
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Affiliation(s)
- Jun Chen
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
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Chen K, Deng J, Ding X, Sun J, Yang S, Liu JZ. Ferromagnetism of 1T'-MoS 2 Nanoribbons Stabilized by Edge Reconstruction and Its Periodic Variation on Nanoribbons Width. J Am Chem Soc 2018; 140:16206-16212. [PMID: 30411616 DOI: 10.1021/jacs.8b09247] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanoribbons (NRs) of two-dimensional (2D) materials have attracted intensive research interests because of exotic physical properties at edges as well as tunable properties via width control. In this paper, using density functional theory (DFT) calculations, we discover sensitive dependence of magnetic properties of 1T'-MoS2 NRs, that is, periodic variation of magnetic moments between 0.1 and 1.2 μ B, on NR width (even or odd number of MoS2 units). Our results reveal that a special edge reconstruction, which is not recognized before, stabilizes the ferromagnetic (FM) ground state. Our results also suggest that the FM state could be stable under ambient condition. This study indicates a promising means to integrate multiple magnetic units for small-scale functional devices, such as information storage and spintronics, on a single piece of MoS2 NR by designing segments with different width.
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Affiliation(s)
- Kaiyun Chen
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Junkai Deng
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Xiangdong Ding
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Jun Sun
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Sen Yang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China
| | - Jefferson Zhe Liu
- Department of Mechanical Engineering , The University of Melbourne , Parkville , Victoria 3010 , Australia
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35
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Kumar P, Chatterjee D, Maeda T, Roy A, Kaneko K, Balakrishnan V. Scalable faceted voids with luminescent enhanced edges in WS 2 monolayers. NANOSCALE 2018; 10:16321-16331. [PMID: 30129965 DOI: 10.1039/c8nr02246a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A scalable approach is needed in the formation of atomically flat edges with specific terminations to enhance local properties for optoelectronic, nanophotonic and energy applications. We demonstrate point defect clustering-driven faceted void formations with luminescent enhanced edges in WS2 monolayers during large-scale CVD growth and controlled annealing. With the aid of aberration-corrected scanning transmission electron microscopy (AC-STEM) high angle annular dark field (HAADF) imaging, we probed atomic terminations of S and W to explain observed luminescence enhancement in alternate edges. Faceted void formation in monolayer WS2 was found to be sensitive to annealing temperature, time, gas environment and precursor supply. Our observations of areal coverage evolution over time revealed competition between monolayer WS2 growth and void formation at 850 °C. While the initial stage was dominated by monolayer growth, defect generation and void growth dominated at later stages and provided an optimum processing window for monolayer WS2 as well as faceted void growth. Growth of faceted voids not only followed the geometry of monolayer facets but also showed similar atomic terminations at the edges and thus enabled local manipulation of photoluminescence enhancement with an order of magnitude increase in intensity. The developed CVD processing enabled multi-fold increase in the luminescent active edge length through the formation of faceted voids within the WS2 monolayer.
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Affiliation(s)
- Pawan Kumar
- School of Engineering, Indian Institute of Technology Mandi, Kamand, H.P. 175005, India.
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36
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Wang N, Cao D, Wang J, Liang P, Chen X, Shu H. Semiconducting edges and flake-shape evolution of monolayer GaSe: role of edge reconstructions. NANOSCALE 2018; 10:12133-12140. [PMID: 29915839 DOI: 10.1039/c8nr03433h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Group-III metal monochalcogenides have emerged as a new class of two-dimensional (2D) semiconductor materials. For the integration of 2D materials for various potential device applications, there is an inevitable need to reduce their dimensionality into specific sized nanostructures with edges. Owing to the properties of finite-sized 2D nanostructures strongly related to the edge configurations, the precise understanding of the edge geometric structures at an atomic level is of particular importance. By means of first-principles calculations, the geometric structures and electronic properties of stable zigzag and armchair edges in a prototype example GaSe monolayer have been identified. Our results demonstrate that both Ga- and Se-terminated zigzag edges prefer to the (3 × 1) reconstructions, and the armchair edges with the perfect flat configuration are energetically favorable. It is unexpectedly found that both zigzag and armchair GaSe nanoribbons with reconstructed edges are semiconductors, which is different from previous recognition where the zigzag edges are metallic. Moreover, the edge-dependent flake shape in GaSe has been plotted using the Wulff construction theory, and the shape evolution with chemical potentials can be applied to explain broad experimental observations on the morphologies of GaSe flakes. Importantly, similar reconstructions and electronic properties also appeared at InSe edges, suggesting that the reconstruction induced semiconducting edges are a fundamental phenomenon for 2D group-III metal monochalcogenides.
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Affiliation(s)
- Ning Wang
- College of Science, China Jiliang University, 310018 Hangzhou, China.
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37
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Wang S, Sawada H, Han X, Zhou S, Li S, Guo ZX, Kirkland AI, Warner JH. Preferential Pt Nanocluster Seeding at Grain Boundary Dislocations in Polycrystalline Monolayer MoS 2. ACS NANO 2018; 12:5626-5636. [PMID: 29762015 DOI: 10.1021/acsnano.8b01418] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We show that Pt nanoclusters preferentially nucleate along the grain boundaries (GBs) in polycrystalline MoS2 monolayer films, with dislocations acting as the seed site. Atomic resolution studies by aberration-corrected annular dark-field scanning transmission electron microscopy reveal periodic spacing of Pt nanoclusters with dependence on GB tilt angles and random spacings for the antiphase boundaries ( i.e., 60°). Individual Pt atoms are imaged within the dislocation core sections of the GB region, with various positions observed, including both the substitutional sites of Mo and the hollow center of the octahedral ring. The evolution from single atoms or small few atom clusters to nanosized particles of Pt is examined at the atomic level to gain a deep understanding of the pathways of Pt seed nucleation and growth at the GB. Density functional theory calculations confirm the energetic advantage of trapping Pt at dislocations on both the antiphase boundary and the small-angle GB rather than on the pristine lattice. The selective decoration of GBs by Pt nanoparticles also has a beneficial use to easily identify GB areas during microscopic-scale observations and track long-range nanoscale variances of GBs with spatial detail not easy to achieve using other methods. We show that GBs have nanoscale meandering across micron-scale distances with no strong preference for specific lattice directions across macroscopic ranges.
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Affiliation(s)
- Shanshan Wang
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
- Science and Technology on Advanced Ceramic Fibers & Composites Laboratory , National University of Defense Technology , Changsha 410073 , Hunan Province , China
| | - Hidetaka Sawada
- JEOL Ltd. , 3-1-2 Musashino , Akishima, Tokyo 196-8558 , Japan
| | - Xiaoyu Han
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Si Zhou
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Sha Li
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
| | - Zheng Xiao Guo
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Angus I Kirkland
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
- Electron Physical Sciences Imaging Center , Diamond Light Source Ltd. , Didcot OX11 0DE , United Kingdom
| | - Jamie H Warner
- Department of Materials , University of Oxford , 16 Parks Road , Oxford OX1 3PH , United Kingdom
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38
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Lin KI, Ho YH, Liu SB, Ciou JJ, Huang BT, Chen C, Chang HC, Tu CL, Chen CH. Atom-Dependent Edge-Enhanced Second-Harmonic Generation on MoS 2 Monolayers. NANO LETTERS 2018; 18:793-797. [PMID: 29327927 DOI: 10.1021/acs.nanolett.7b04006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Edge morphology and lattice orientation of single-crystal molybdenum disulfide (MoS2) monolayers, a transition metal dichalcogenide (TMD), possessing a triangular shape with different edges grown by chemical vapor deposition are characterized by atomic force microscopy and transmission electron microscopy. Multiphoton laser scanning microscopy is utilized to study one-dimensional atomic edges of MoS2 monolayers with localized midgap electronic states, which result in greatly enhanced optical second-harmonic generation (SHG). Microscopic S-zigzag edge and S-Mo Klein edge (bare Mo atoms protruding from a S-zigzag edge) terminations and the edge-atom dependent resonance energies can therefore be deduced based on SHG images. Theoretical calculations based on density functional theory clearly explain the lower energy of the S-zigzag edge states compared to the corresponding S-Mo Klein edge states. Characterization of the atomic-scale variation of edge-enhanced SHG is a step forward in this full-optical and high-yield technique of atomic-layer TMDs.
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Affiliation(s)
- Kuang-I Lin
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
| | - Yen-Hung Ho
- National Center for Theoretical Sciences and Department of Physics, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Shu-Bai Liu
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
| | - Jian-Jhih Ciou
- Department of Automatic Control Engineering, Feng Chia University , Taichung 40724, Taiwan
| | - Bo-Ting Huang
- Center for Micro/Nano Science and Technology, National Cheng Kung University , Tainan 70101, Taiwan
| | - Christopher Chen
- Department of Electrical Engineering, University of California , Los Angeles, California 90095, United States
| | - Han-Ching Chang
- Department of Automatic Control Engineering, Feng Chia University , Taichung 40724, Taiwan
| | - Chien-Liang Tu
- Department of Automatic Control Engineering, Feng Chia University , Taichung 40724, Taiwan
| | - Chang-Hsiao Chen
- Department of Automatic Control Engineering, Feng Chia University , Taichung 40724, Taiwan
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39
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Wang S, Robertson A, Warner JH. Atomic structure of defects and dopants in 2D layered transition metal dichalcogenides. Chem Soc Rev 2018; 47:6764-6794. [DOI: 10.1039/c8cs00236c] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Transmission electron microscopy can directly image the detailed atomic structure of layered transition metal dichalcogenides, revealing defects and dopants.
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Affiliation(s)
- Shanshan Wang
- Science and Technology on Advanced Ceramic Fibers and Composites Laboratory
- College of Aerospace Science and Engineering
- National University of Defense Technology
- Changsha 410073
- P. R. China
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