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Zou G, Sow CH, Wang Z, Chen X, Gao H. Mechanomaterials and Nanomechanics: Toward Proactive Design of Material Properties and Functionalities. ACS Nano 2024; 18:11492-11502. [PMID: 38676670 DOI: 10.1021/acsnano.4c03194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2024]
Abstract
While conventional mechanics of materials offers a passive understanding of the mechanical properties of materials in existing forms, a paradigm shift, referred to as mechanomaterials, is emerging to enable the proactive programming of materials' properties and functionalities by leveraging force-geometry-property relationships. One of the foundations of this new paradigm is nanomechanics, which permits functional and structural materials to be designed based on principles from the nanoscale and beyond. Although the field of mechanomaterials is still in its infancy at the present time, we discuss the current progress in three specific directions closely linked to nanomechanics and provide perspectives on these research foci by considering the potential research directions, chances for success, and existing research capabilities. We believe this new research paradigm will provide future materials solutions for infrastructure, healthcare, energy, and environment.
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Affiliation(s)
- Guijin Zou
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Zhisong Wang
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Xiaodong Chen
- Innovative Center for Flexible Devices (iFLEX), Max Planck-NTU Joint Laboratory for Artificial Senses, School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore 639798, Singapore
- Mechano-X Institute, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
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2
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Sow MMG, Zhang Z, Sow CH, Lim SX. Author Correction: Upcycling fish scales through heating for steganography and Rhodamine B adsorption application. Nat Commun 2023; 14:7713. [PMID: 38001064 PMCID: PMC10673822 DOI: 10.1038/s41467-023-43515-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023] Open
Affiliation(s)
- Malcolm Miao Geng Sow
- NUS High School of Mathematics and Science, 20 Clementi Avenue 1, Singapore, 129957, Singapore
| | - Zheng Zhang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore, 138634, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
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3
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Sow MMG, Zhang Z, Sow CH, Lim SX. Upcycling fish scales through heating for steganography and Rhodamine B adsorption application. Nat Commun 2023; 14:6508. [PMID: 37845200 PMCID: PMC10579236 DOI: 10.1038/s41467-023-42080-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 09/29/2023] [Indexed: 10/18/2023] Open
Abstract
With increasing population and limited resources, a potential route for improving sustainability is increased reuse of waste materials. By re-looking at wastes, interesting properties and multifunctionalities can be discovered in materials previously explored. Despite years of research on bio-compatible fish scales, there is limited study on the fluorescence property of this abundant waste material. Controlled denaturation of collagen and introduction of defects can serve as a means to transform the fluorescence property of these fish scale wastes while providing more adsorption sites for pollutant removal, turning multifunctional fish scales into a natural steganographic material for transmitting text and images at both the macroscopic and microscopic levels and effectively removing Rhodamine B pollutants (91 % removal) within a short contact time (10 minutes). Our work offers a glimpse into the realm of engineering defects-induced fluorescence in natural material with potential as bio-compatible fluorescence probes while encouraging multidimensional applicability to be established in otherwise overlooked waste resources.
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Affiliation(s)
- Malcolm Miao Geng Sow
- NUS High School of Mathematics and Science, 20 Clementi Avenue 1, Singapore, 129957, Singapore
| | - Zheng Zhang
- Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore, 138634, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
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4
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Wang X, Zhao Y, Kong X, Zhang Q, Ng HK, Lim SX, Zheng Y, Wu X, Watanabe K, Xu QH, Taniguchi T, Eda G, Goh KEJ, Jin S, Loh KP, Ding F, Sun W, Sow CH. Dynamic Tuning of Moiré Superlattice Morphology by Laser Modification. ACS Nano 2022; 16:8172-8180. [PMID: 35575066 DOI: 10.1021/acsnano.2c01625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In artificial van der Waals (vdW) layered devices, twisting the stacking angle has emerged as an effective strategy to regulate the electronic phases and optical properties of these systems. Along with the twist registry, the lattice reconstruction arising from vdW interlayer interaction has also inspired significant research interests. The control of twist angles is significantly important because the moiré periodicity determines the electron propagation length on the lattice and the interlayer electron-electron interactions. However, the moiré periodicity is hard to be modified after the device has been fabricated. In this work, we have demonstrated that the moiré periodicity can be precisely modulated with a localized laser annealing technique. This is achieved with regulating the interlayer lattice mismatch by the mismatched lattice constant, which originates from the variable density of sulfur vacancy generated during laser modification. The existence of sulfur vacancy is further verified by excitonic emission energy and lifetime in photoluminescence measurements. Furthermore, we also discover that the mismatched lattice constant has the equivalent contribution as the twist angle for determining the lattice mismatch. Theoretical modeling elaborates the moiré-wavelength-dependent energy variations at the interface and mimics the evolution of moiré morphology.
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Affiliation(s)
- Xinyun Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Yuzhou Zhao
- Department of Chemistry, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States
| | - Xiao Kong
- Centre for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Korea 44919
| | - Qi Zhang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Hong Kuan Ng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Sharon Xiaodai Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Yue Zheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Xiao Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Namiki Tsukuba, Ibaraki Japan 305-0044
| | - Qing-Hua Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Namiki Tsukuba, Ibaraki Japan 305-0044
| | - Goki Eda
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Kuan Eng Johnson Goh
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Singapore 138634
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Song Jin
- Department of Chemistry, University of Wisconsin─Madison, Madison, Wisconsin 53706, United States
| | - Kian Ping Loh
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Feng Ding
- Centre for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan, Korea 44919
| | - Wanxin Sun
- Bruker Nano Surface Division, 30 Biopolis Street 09-01, The Matrix, Singapore 138671
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546
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5
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Ma Y, Shao X, Li J, Dong B, Hu Z, Zhou Q, Xu H, Zhao X, Fang H, Li X, Li Z, Wu J, Zhao M, Pennycook SJ, Sow CH, Lee C, Zhong YL, Lu J, Ding M, Wang K, Li Y, Lu J. Electrochemically Exfoliated Platinum Dichalcogenide Atomic Layers for High-Performance Air-Stable Infrared Photodetectors. ACS Appl Mater Interfaces 2021; 13:8518-8527. [PMID: 33569955 DOI: 10.1021/acsami.0c20535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Platinum dichalcogenide (PtX2), an emergent group-10 transition metal dichalcogenide (TMD) has shown great potential in infrared photonic and optoelectronic applications due to its layer-dependent electronic structure with potentially suitable bandgap. However, a scalable synthesis of PtSe2 and PtTe2 atomic layers with controlled thickness still represents a major challenge in this field because of the strong interlayer interactions. Herein, we develop a facile cathodic exfoliation approach for the synthesis of solution-processable high-quality PtSe2 and PtTe2 atomic layers for high-performance infrared (IR) photodetection. As-exfoliated PtSe2 and PtTe2 bilayer exhibit an excellent photoresponsivity of 72 and 1620 mA W-1 at zero gate voltage under a 1540 nm laser illumination, respectively, approximately several orders of magnitude higher than that of the majority of IR photodetectors based on graphene, TMDs, and black phosphorus. In addition, our PtSe2 and PtTe2 bilayer device also shows a decent specific detectivity of beyond 109 Jones with remarkable air-stability (>several months), outperforming the mechanically exfoliated counterparts under the laser illumination with a similar wavelength. Moreover, a high yield of PtSe2 and PtTe2 atomic layers dispersed in solution also allows for a facile fabrication of air-stable wafer-scale IR photodetector. This work demonstrates a new route for the synthesis of solution-processable layered materials with the narrow bandgap for the infrared optoelectronic applications.
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Affiliation(s)
- Yaping Ma
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Xiji Shao
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jing Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
| | - Bowei Dong
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Zhenliang Hu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Qiulan Zhou
- Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Haomin Xu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Xiaoxu Zhao
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Hanyan Fang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Xinzhe Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Zejun Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Jing Wu
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Sigapore 138634, Singapore
| | - Meng Zhao
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Sigapore 138634, Singapore
| | - Stephen John Pennycook
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Yu Lin Zhong
- Centre for Clean Environment and Energy, School of Environment and Science, Griffith University, Gold Coast, Queensland 4222, Australia
| | - Junpeng Lu
- School of Physics, Southeast University, Nanjing 211189, China
| | - Mengning Ding
- Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Kedong Wang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Ying Li
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 2 Science Drive 3, Singapore 117546, Singapore
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6
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Hu Z, Avila J, Wang X, Leong JF, Zhang Q, Liu Y, Asensio MC, Lu J, Carvalho A, Sow CH, Castro Neto AH. The Role of Oxygen Atoms on Excitons at the Edges of Monolayer WS 2. Nano Lett 2019; 19:4641-4650. [PMID: 31189314 DOI: 10.1021/acs.nanolett.9b01670] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We clarify that the chemisorption of oxygen atoms at the edges is a key contributor to the frequently observed edge enhancement and spatial non-uniformities of photoluminescence (PL) in WS2 monolayers. Here we have investigated with momentum- and real-space nanoimaging of the chemical and electronic density inhomogeneity of WS2 flakes. Our finding from a large panoply of techniques together with density functional theory calculation confirms that the oxygen chemisorption leads to the electron accumulation at the edges. This facilitates the trion dominance of PL at the edges of WS2 flakes. Our results highlight and unravel the significance of chemisorbed oxygen at the edges in the PL emission and electronic structure of WS2, providing a viable path to enhance the performance of transition-metal-dichalcogenide-based devices.
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Affiliation(s)
- Zhenliang Hu
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
- Center for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
| | - Jose Avila
- ANTARES Beamline , Synchrotron SOLEIL and Université Paris-Saclay , L'Orme des Merisiers , 91192 Gif sur Yvette , Cedex, France
| | - Xinyun Wang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
- Center for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
| | - Jin Feng Leong
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
| | - Qi Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
| | - Yanpeng Liu
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, and Institute of Nanoscience , Nanjing University of Aeronautics and Astronautics , Nanjing 210016 , China
| | - Maria C Asensio
- Instituto de Materiales de Madrid, CSIC , C/Sor Juana Inés de la Cruz, 3 Cantoblanco , 28049 Madrid , Spain
| | - Junpeng Lu
- School of Physics , Southeast University , 2 Southeast University Road , Nanjing 211189 , China
| | - Alexandra Carvalho
- Center for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
| | - Chorng Haur Sow
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
- Center for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
| | - Antonio Helio Castro Neto
- Department of Physics , National University of Singapore , 2 Science Drive 3 , 117542 Singapore
- Center for Advanced 2D Materials , National University of Singapore , 6 Science Drive 2 , 117546 Singapore
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7
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Bah A, Lim KY, Wei F, Khursheed A, Sow CH. Fluorescence Invigoration in Carbon-Incorporated Zinc Oxide Nanowires from Passage of Field Emission Electrons. Sci Rep 2019; 9:9671. [PMID: 31273272 PMCID: PMC6609609 DOI: 10.1038/s41598-019-46177-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 06/20/2019] [Indexed: 11/09/2022] Open
Abstract
We demonstrate that carbon incorporated Zinc Oxide (C-ZnO) nanowires (NWs) exhibit remarkable improvement in the extent and quality of fluorescence emission after they are utilized as an electron source in a field emission experiment. After the passage of field emission electrons, the intensity of the fluorescence emitted from these NWs in the visible light range exhibits a 2.5 to 8 fold enhancement. The intrinsic exciton peak of the ZnO also becomes heightened, along with the crystalline quality of the NWs showing marked improvement. This invigoration of fluorescence across the entire fluorescence spectrum is attributed to concurrent removal of oxygen and carbon atoms in C-ZnO NWs due to electro-migration of atoms and joule heating during the field emission process. Applications based on ZnO NWs emission from excitonic emissions or visible wavelength emissions or both can benefit from this straightforward method of defect engineering.
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Affiliation(s)
- Andrew Bah
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Kim Yong Lim
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Fuhua Wei
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Anjam Khursheed
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore.
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8
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Lu J, Liu H, Zhang X, Sow CH. One-dimensional nanostructures of II-VI ternary alloys: synthesis, optical properties, and applications. Nanoscale 2018; 10:17456-17476. [PMID: 30211428 DOI: 10.1039/c8nr05019h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
One-dimensional (1D) nanostructures of II-VI ternary alloys are of prime interest due to their compatible features of both 1D nanostructures and semiconducting alloys. These features can facilitate materials with tunable bandgaps, which are crucial to the performance of photoelectrical devices. Herein, we present a comprehensive review summarizing the recent research progress pertinent to the diverse synthesis, optical fundamentals and applications of 1D nanostructures of II-VI ternary alloys. Considering multifunctional applications, the different growth mechanisms of the rational design and synthesis techniques are highlighted. Investigations of the fundamentals of the optical and photoelectrical properties of ternary alloyed II-VI semiconductors via the corresponding characterization techniques are also particularly discussed. Furthermore, we present the versatile potential practical applications of these materials. Finally, we extend the discussion to the most recent research advances on quaternary alloys, which provides a possible prospective forecast for the sustained development of alloyed 1D nanostructures.
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Affiliation(s)
- Junpeng Lu
- School of Physics, Southeast University, 2 Southeast University Road, Nanjing 211189, China.
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9
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Liu Y, Rodrigues JNB, Luo YZ, Li L, Carvalho A, Yang M, Laksono E, Lu J, Bao Y, Xu H, Tan SJR, Qiu Z, Sow CH, Feng YP, Neto AHC, Adam S, Lu J, Loh KP. Tailoring sample-wide pseudo-magnetic fields on a graphene-black phosphorus heterostructure. Nat Nanotechnol 2018; 13:828-834. [PMID: 29941889 DOI: 10.1038/s41565-018-0178-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 05/23/2018] [Indexed: 05/22/2023]
Abstract
Spatially tailored pseudo-magnetic fields (PMFs) can give rise to pseudo-Landau levels and the valley Hall effect in graphene. At an experimental level, it is highly challenging to create the specific strain texture that can generate PMFs over large areas. Here, we report that superposing graphene on multilayer black phosphorus creates shear-strained superlattices that generate a PMF over an entire graphene-black phosphorus heterostructure with edge size of tens of micrometres. The PMF is intertwined with the spatial period of the moiré pattern, and its spatial distribution and intensity can be modified by changing the relative orientation of the two materials. We show that the emerging pseudo-Landau levels influence the transport properties of graphene-black phosphorus field-effect transistor devices with Hall bar geometry. The application of an external magnetic field allows us to enhance or reduce the effective field depending on the valley polarization with the prospect of developing a valley filter.
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Affiliation(s)
- Yanpeng Liu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
| | - J N B Rodrigues
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Yong Zheng Luo
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Linjun Li
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
| | - Alexandra Carvalho
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Ming Yang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore, Singapore
| | - Evan Laksono
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Junpeng Lu
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Yang Bao
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
| | - Hai Xu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
| | - Sherman J R Tan
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Zhizhan Qiu
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore
| | - Chorng Haur Sow
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Yuan Ping Feng
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - A H Castro Neto
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore
- Department of Physics, National University of Singapore, Singapore, Singapore
| | - Shaffique Adam
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore.
- Department of Physics, National University of Singapore, Singapore, Singapore.
- Yale-NUS College, Singapore, Singapore.
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore.
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore.
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10
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Gogoi PK, Hu Z, Wang Q, Carvalho A, Schmidt D, Yin X, Chang YH, Li LJ, Sow CH, Neto AHC, Breese MBH, Rusydi A, Wee ATS. Oxygen Passivation Mediated Tunability of Trion and Excitons in MoS_{2}. Phys Rev Lett 2017; 119:077402. [PMID: 28949667 DOI: 10.1103/physrevlett.119.077402] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 06/07/2023]
Abstract
Using wide spectral range in situ spectroscopic ellipsometry with systematic ultrahigh vacuum annealing and in situ exposure to oxygen, we report the complex dielectric function of MoS_{2} isolating the environmental effects and revealing the crucial role of unpassivated and passivated sulphur vacancies. The spectral weights of the A (1.92 eV) and B (2.02 eV) exciton peaks in the dielectric function reduce significantly upon annealing, accompanied by spectral weight transfer in a broad energy range. Interestingly, the original spectral weights are recovered upon controlled oxygen exposure. This tunability of the excitonic effects is likely due to passivation and reemergence of the gap states in the band structure during oxygen adsorption and desorption, respectively, as indicated by ab initio density functional theory calculation results. This Letter unravels and emphasizes the important role of adsorbed oxygen in the optical spectra and many-body interactions of MoS_{2}.
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Affiliation(s)
- Pranjal Kumar Gogoi
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - Zhenliang Hu
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
| | - Qixing Wang
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
| | - Alexandra Carvalho
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117542, Singapore
| | - Daniel Schmidt
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - Xinmao Yin
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
| | - Yung-Huang Chang
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Lain-Jong Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Chorng Haur Sow
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117542, Singapore
| | - A H Castro Neto
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117542, Singapore
| | - Mark B H Breese
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore
| | - Andrivo Rusydi
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore
- NUSNNI-NanoCore, National University of Singapore, Singapore 117576, Singapore
| | - Andrew T S Wee
- Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117542, Singapore
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11
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Nayak TR, Wang H, Pant A, Zheng M, Junginger H, Goh WJ, Lee CK, Zou S, Alonso S, Czarny B, Storm G, Sow CH, Lee C, Pastorin G. ZnO Nano-Rod Devices for Intradermal Delivery and Immunization. Nanomaterials (Basel) 2017; 7:nano7060147. [PMID: 28617335 PMCID: PMC5485794 DOI: 10.3390/nano7060147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/09/2017] [Accepted: 06/09/2017] [Indexed: 11/23/2022]
Abstract
Intradermal delivery of antigens for vaccination is a very attractive approach since the skin provides a rich network of antigen presenting cells, which aid in stimulating an immune response. Numerous intradermal techniques have been developed to enhance penetration across the skin. However, these methods are invasive and/or affect the skin integrity. Hence, our group has devised zinc oxide (ZnO) nano-rods for non-destructive drug delivery. Chemical vapour deposition was used to fabricate aligned nano-rods on ZnO pre-coated silicon chips. The nano-rods’ length and diameter were found to depend on the temperature, time, quality of sputtered silicon chips, etc. Vertically aligned ZnO nano-rods with lengths of 30–35 µm and diameters of 200–300 nm were selected for in vitro human skin permeation studies using Franz cells with Albumin-fluorescein isothiocyanate (FITC) absorbed on the nano-rods. Fluorescence and confocal studies on the skin samples showed FITC penetration through the skin along the channels formed by the nano-rods. Bradford protein assay on the collected fluid samples indicated a significant quantity of Albumin-FITC in the first 12 h. Low antibody titres were observed with immunisation on Balb/c mice with ovalbumin (OVA) antigen coated on the nano-rod chips. Nonetheless, due to the reduced dimensions of the nano-rods, our device offers the additional advantage of excluding the simultaneous entrance of microbial pathogens. Taken together, these results showed that ZnO nano-rods hold the potential for a safe, non-invasive, and painless intradermal drug delivery.
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Affiliation(s)
- Tapas R Nayak
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
| | - Hao Wang
- Department of Electrical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Aakansha Pant
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
| | - Minrui Zheng
- Department of Physics, National University of Singapore, Singapore 117551, Singapore.
| | - Hans Junginger
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
| | - Wei Jiang Goh
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
- NUS Graduate School for Integrative Sciences and Engineering, Centre for Life Sciences (CeLS), Singapore 117456, Singapore.
| | - Choon Keong Lee
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
| | - Shui Zou
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
| | - Sylvie Alonso
- Department of Microbiology, National University of Singapore, Singapore 117545, Singapore.
| | - Bertrand Czarny
- School of Materials Science and Engineering (MSE) & Lee Kong Chian School of medicine (LKCmedicine), Nanyang Technological University, Singapore 636921, Singapore.
| | - Gert Storm
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, Singapore 117551, Singapore.
| | - Chengkuo Lee
- Department of Electrical Engineering, National University of Singapore, Singapore 117583, Singapore.
| | - Giorgia Pastorin
- Department of Pharmacy, National University of Singapore, Singapore 117583, Singapore.
- Department of Physics, National University of Singapore, Singapore 117551, Singapore.
- NUSNNI-NanoCore, National University of Singapore, T-Lab, Blk E3-05-29, 2 Engineering Drive 3, Singapore 117581, Singapore.
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12
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Venkatakrishnan A, Chua H, Tan P, Hu Z, Liu H, Liu Y, Carvalho A, Lu J, Sow CH. Microsteganography on WS 2 Monolayers Tailored by Direct Laser Painting. ACS Nano 2017; 11:713-720. [PMID: 28033460 DOI: 10.1021/acsnano.6b07118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present scanning focused laser beam as a multipurpose tool to engineer the physical and chemical properties of WS2 microflakes. For monolayers, the laser modification integrates oxygen into the WS2 microflake, resulting in ∼9 times enhancement in the intensity of the fluorescence emission. This modification does not cause any morphology change, allowing "micro-encryption" of information that is only observable as fluorescence under excitation. The same focused laser also facilitates on demand thinning down of WS2 multilayers into monolayers, turning them into fluorescence active components. With a scanning focused laser beam, micropatterns are readily created on WS2 multilayers through selective thinning of specific regions on the flake.
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Affiliation(s)
| | - Hou Chua
- NUS High School of Mathematics and Science , 20 Clementi Avenue 1, Singapore 129957
| | - Pinxi Tan
- NUS High School of Mathematics and Science , 20 Clementi Avenue 1, Singapore 129957
| | - Zhenliang Hu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Hongwei Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology, and Research (A*STAR) , 2 Fusionopolis Way, lnnovis, #08-03, Singapore 138634
| | - Yanpeng Liu
- Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 3, Singapore 117546
| | - Alexandra Carvalho
- Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 3, Singapore 117546
| | - Junpeng Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 3, Singapore 117546
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 3, Singapore 117546
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13
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Abstract
Since the beginning of 2014, phosphorene, a monolayer or few-layer of black phosphorus, has been rediscovered as a two-dimensional (2D) thin film, revealing a plethora of properties different from the bulk material studied so far. Similar to graphene and transition metal dichalcogenides (TMDs), phosphorene is also a layered material that can be exfoliated to yield individual layers. It is one of the few monoelemental 2D crystals and the only one, besides graphene, known to be stable in monolayer, few layer, and bulk form. Recently the intensified research in phosphorene is motivated not only by the study of its fundamental physical properties in the 2D regime, such as tunable bandgap and anisotropic behavior, but also by the high carrier mobility and good on/off ratio of phosphorene-based device prototypes, making it a potential alternative for next generation nanooptoelectronics and nanophotonics applications in the "post-graphene age" The electronic bandgap of phosphorene changes from 0.3 eV in the bulk to 2.1 eV in monolayer. Thus, phosphorene exhibits strong light-matter interactions in the visible and infrared (IR) frequencies. In this Account, we present the progress on understanding the various interactions between light and phosphorene, giving insight into the mechanism of these interactions and the respective applications. We begin by discussing the fundamental optical properties of phosphorene, using theoretical calculations to depict the layer-dependent electronic band structures and anisotropic optical properties. Many-body effects in phosphorene, including excitons and trions and their binding energies and dynamics are reviewed as observed in experiments. For phosphorene, the fast degradation in ambient condition, caused by photoinduced oxidation, is considered as a longstanding challenge. In contrast, oxidation can be used to engineer the band structure of phosphorene and, in parallel, its optical properties. Based on the strong light-matter interactions, we introduce a controllable method to directly oxidize phosphorene by laser techniques. With the oxidization induced by laser scanning, localized bandgap engineering can be achieved and microphotonics are demonstrated on the oxidized phosphorene. Finally, we will present a brief discussion on the realization of phosphorene-based building blocks of optoelectronic devices. Naturally, the strong light-matter interactions in phosphorene could enable efficient photoelectric conversion in optoelectronic devices. We will describe high performance photodetectors based on phosphorene, and the working mechanism of those devices will be introduced. The photovoltaic effect could also be exhibited in phosphorene. This indicates the pervasive potential of phosphorene in nanooptoelectronics.
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Affiliation(s)
- Junpeng Lu
- Department
of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore
- Center
for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, 117546 Singapore
| | - Jiong Yang
- Research
School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Alexandra Carvalho
- Center
for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, 117546 Singapore
| | - Hongwei Liu
- Institute
of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, #08-03, 138634 Singapore
| | - Yuerui Lu
- Research
School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Chorng Haur Sow
- Department
of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore
- Center
for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, 117546 Singapore
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14
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Liu H, Lu J, Ho K, Hu Z, Dang Z, Carvalho A, Tan HR, Tok ES, Sow CH. Fluorescence Concentric Triangles: A Case of Chemical Heterogeneity in WS2 Atomic Monolayer. Nano Lett 2016; 16:5559-5567. [PMID: 27479127 DOI: 10.1021/acs.nanolett.6b02111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report a novel optical property in WS2 monolayer. The monolayer naturally exhibits beautiful in-plane periodical and lateral homojunctions by way of alternate dark and bright band in the fluorescence images of these monolayers. The interface between different fluorescence species within the sample is distinct and sharp. This gives rise to intriguing concentric triangular fluorescence patterns in the monolayer. The novel optical property of this special WS2 monolayer is facilitated by chemical heterogeneity. The photoluminescence of the bright band is dominated by emissions from trion and biexciton while the emission from defect-bound exciton dominates the photoluminescence at the dark band. The discovery of such concentric fluorescence patterns represents a potentially new form of optoelectronic or photonic functionality.
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Affiliation(s)
- Hongwei Liu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03, Singapore 138634
| | - Junpeng Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546
| | - Kenneth Ho
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Zhenliang Hu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Zhiya Dang
- Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163, Genova, Italy
| | - Alexandra Carvalho
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546
| | - Hui Ru Tan
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03, Singapore 138634
| | - Eng Soon Tok
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546
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15
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Lu J, Carvalho A, Liu H, Lim SX, Castro Neto AH, Sow CH. Hybrid Bilayer WSe2-CH3NH3PbI3Organolead Halide Perovskite as a High-Performance Photodetector. Angew Chem Int Ed Engl 2016; 55:11945-9. [DOI: 10.1002/anie.201603557] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/26/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Junpeng Lu
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Alexandra Carvalho
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Hongwei Liu
- Institute of Materials Research and Engineering; A*STAR (Agency for Science, Technology and Research); 2 Fusionopolis Way. Innovis, #08-03 Singapore 138634 Singapore
| | - Sharon Xiaodai Lim
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
| | - Antonio H. Castro Neto
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Chorng Haur Sow
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
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16
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Lu J, Carvalho A, Liu H, Lim SX, Castro Neto AH, Sow CH. Hybrid Bilayer WSe2-CH3NH3PbI3Organolead Halide Perovskite as a High-Performance Photodetector. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603557] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Junpeng Lu
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Alexandra Carvalho
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Hongwei Liu
- Institute of Materials Research and Engineering; A*STAR (Agency for Science, Technology and Research); 2 Fusionopolis Way. Innovis, #08-03 Singapore 138634 Singapore
| | - Sharon Xiaodai Lim
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
| | - Antonio H. Castro Neto
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
| | - Chorng Haur Sow
- Department of Physics; National University of Singapore; 2 Science Drive 3 Singapore 117542 Singapore
- Center for Advanced 2D Materials and Graphene Research Center; National University of Singapore; 6 Science Drive 2 Singapore 117546 Singapore
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17
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Liu H, Lu J, Yang Z, Teng J, Ke L, Zhang X, Tong L, Sow CH. Ultrahigh photoconductivity of bandgap-graded CdSxSe1-x nanowires probed by terahertz spectroscopy. Sci Rep 2016; 6:27387. [PMID: 27263861 PMCID: PMC4893690 DOI: 10.1038/srep27387] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/16/2016] [Indexed: 11/09/2022] Open
Abstract
Superiorly high photoconductivity is desirable in optoelectronic materials and devices for information transmission and processing. Achieving high photoconductivity via bandgap engineering in a bandgap-graded semiconductor nanowire has been proposed as a potential strategy. In this work, we report the ultrahigh photoconductivity of bandgap-graded CdSxSe1-x nanowires and its detailed analysis by means of ultrafast optical-pump terahertz-probe (OPTP) spectroscopy. The recombination rates and carrier mobility are quantitatively obtained via investigation of the transient carrier dynamics in the nanowires. By analysis of the terahertz (THz) spectra, we obtain an insight into the bandgap gradient and band alignment to carrier transport along the nanowires. The demonstration of the ultrahigh photoconductivity makes bandgap-graded CdSxSe1-x nanowires a promising candidate as building blocks for nanoscale electronic and photonic devices.
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Affiliation(s)
- Hongwei Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, 138634, Singapore
| | - Junpeng Lu
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Zongyin Yang
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, 138634, Singapore
| | - Lin Ke
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, 138634, Singapore
| | - Xinhai Zhang
- Department of Electrical and Electronic Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Nanshan District, Shenzhen, Guangdong, 518055, China
| | - Limin Tong
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China
| | - Chorng Haur Sow
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
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18
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Lu J, Carvalho A, Wu J, Liu H, Tok ES, Neto AHC, Özyilmaz B, Sow CH. Enhanced Photoresponse from Phosphorene-Phosphorene-Suboxide Junction Fashioned by Focused Laser Micromachining. Adv Mater 2016; 28:4090-4096. [PMID: 27028659 DOI: 10.1002/adma.201506201] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/04/2016] [Indexed: 06/05/2023]
Abstract
Enhanced photoresponse is obtained from phosphorene-phosphorene-suboxide. A scanning focused laser beam is employed as a straightforward approach to convert part of a phosphorene film into phosphorene suboxide, creating a functional junction in situ on an optoelectronic device based on phosphorene. As a result, the photoelectrical properties of the optoelectronic device are significantly improved.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Alexandra Carvalho
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Jing Wu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Hongwei Liu
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way. Innovis, #08-03, Singapore, 138634, Singapore
| | - Eng Soon Tok
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Antonio H Castro Neto
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Barbaros Özyilmaz
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
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19
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Lu J, Carvalho A, Wu J, Liu H, Tok ES, Neto AHC, Özyilmaz B, Sow CH. Phosphorene: Enhanced Photoresponse from Phosphorene-Phosphorene-Suboxide Junction Fashioned by Focused Laser Micromachining (Adv. Mater. 21/2016). Adv Mater 2016; 28:4164. [PMID: 27246921 DOI: 10.1002/adma.201670146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
On page 4090, B. Özyilmaz, C. H. Sow, and co-workers use a focused laser beam to modify the surface of a phosphorene device. With a simple focused laser beam, a part of the phosphorene can be scanned and converted into phosphorene-suboxide species, leaving behind a functional and active phosphorene-phosphorene suboxide junction in the device. Once the junction is formed, the photoresponsivity and photocurrent distribution of the device can be significantly altered with a qualitative difference in behavior. Photovoltaic-like behavior is observed, which is not found in the pristine sample.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Alexandra Carvalho
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Jing Wu
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Hongwei Liu
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way. Innovis, #08-03, Singapore, 138634, Singapore
| | - Eng Soon Tok
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
| | - Antonio H Castro Neto
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Barbaros Özyilmaz
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
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20
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Handoko AD, Deng S, Deng Y, Cheng AWF, Chan KW, Tan HR, Pan Y, Tok ES, Sow CH, Yeo BS. Enhanced activity of H2O2-treated copper(ii) oxide nanostructures for the electrochemical evolution of oxygen. Catal Sci Technol 2016. [DOI: 10.1039/c5cy00861a] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
H2O2-treated CuO nanostructures show 40–68× higher OER activity than Cu nanoparticles.
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Affiliation(s)
| | - Suzi Deng
- Department of Physics
- National University of Singapore
- 117542 Singapore
| | - Yilin Deng
- Department of Chemistry
- National University of Singapore
- 117543 Singapore
| | | | - Kuang Wen Chan
- Department of Chemistry
- National University of Singapore
- 117543 Singapore
| | - Hui Ru Tan
- Institute of Materials Research and Engineering
- A*STAR (Agency for Science, Technology and Research)
- 3 Research Link
- 117602 Singapore
| | - Yanlin Pan
- Department of Chemistry
- National University of Singapore
- 117543 Singapore
| | - Eng Soon Tok
- Department of Physics
- National University of Singapore
- 117542 Singapore
| | - Chorng Haur Sow
- Department of Physics
- National University of Singapore
- 117542 Singapore
| | - Boon Siang Yeo
- Department of Chemistry
- National University of Singapore
- 117543 Singapore
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21
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Lu J, Wu J, Carvalho A, Ziletti A, Liu H, Tan J, Chen Y, Castro Neto AH, Özyilmaz B, Sow CH. Bandgap Engineering of Phosphorene by Laser Oxidation toward Functional 2D Materials. ACS Nano 2015; 9:10411-10421. [PMID: 26364647 DOI: 10.1021/acsnano.5b04623] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We demonstrate a straightforward and effective laser pruning approach to reduce multilayer black phosphorus (BP) to few-layer BP under ambient condition. Phosphorene oxides and suboxides are formed and the degree of laser-induced oxidation is controlled by the laser power. Since the band gaps of the phosphorene suboxide depend on the oxygen concentration, this simple technique is able to realize localized band gap engineering of the thin BP. Micropatterns of few-layer phosphorene suboxide flakes with unique optical and fluorescence properties are created. Remarkably, some of these suboxide flakes display long-term (up to 2 weeks) stability in ambient condition. Comparing against the optical properties predicted by first-principle calculations, we develop a "calibration" map in using focused laser power as a handle to tune the band gap of the BP suboxide flake. Moreover, the surface of the laser patterned region is altered to be sensitive to toxic gas by way of fluorescence contrast. Therefore, the multicolored display is further demonstrated as a toxic gas monitor. In addition, the BP suboxide flake is demonstrated to exhibit higher drain current modulation and mobility comparable to that of the pristine BP in the electronic application.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
| | - Jing Wu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
| | - Alexandra Carvalho
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore
| | - Angelo Ziletti
- Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Hongwei Liu
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 3 Research Link, Singapore 117602, Singapore
| | - Junyou Tan
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore
| | - Yifan Chen
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 3 Research Link, Singapore 117602, Singapore
| | - A H Castro Neto
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore
| | - Barbaros Özyilmaz
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore
| | - Chorng Haur Sow
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
- Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore
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Lu J, Carvalho A, Chan XK, Liu H, Liu B, Tok ES, Loh KP, Castro Neto AH, Sow CH. Atomic healing of defects in transition metal dichalcogenides. Nano Lett 2015; 15:3524-32. [PMID: 25923457 DOI: 10.1021/acs.nanolett.5b00952] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
As-grown transition metal dichalcogenides are usually chalcogen deficient and therefore contain a high density of chalcogen vacancies, deep electron traps which can act as charged scattering centers, reducing the electron mobility. However, we show that chalcogen vacancies can be effectively passivated by oxygen, healing the electronic structure of the material. We proposed that this can be achieved by means of surface laser modification and demonstrate the efficiency of this processing technique, which can enhance the conductivity of monolayer WSe2 by ∼400 times and its photoconductivity by ∼150 times.
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Affiliation(s)
- Junpeng Lu
- †Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Alexandra Carvalho
- ‡Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Xinhui Kim Chan
- †Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Hongwei Liu
- §Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602
| | - Bo Liu
- ‡Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Eng Soon Tok
- †Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
| | - Kian Ping Loh
- ‡Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore 117546
- ∥Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - A H Castro Neto
- †Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- ‡Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore 117546
| | - Chorng Haur Sow
- †Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
- ‡Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore 117546
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Lu J, Lu JH, Liu H, Liu B, Gong L, Tok ES, Loh KP, Sow CH. Microlandscaping of Au nanoparticles on few-layer MoS2 films for chemical sensing. Small 2015; 11:1792-800. [PMID: 25581016 DOI: 10.1002/smll.201402591] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/18/2014] [Indexed: 05/13/2023]
Abstract
Surface modification or decoration of ultrathin MoS2 films with chemical moieties is appealing since nanointerfacing can functionalize MoS2 films with bonus potentials. In this work, a facile and effective method for microlandscaping of Au nanoparticles (NPs) on few-layer MoS2 films is developed. This approach first employs a focused laser beam to premodify the MoS2 films to achieve active surface domains with unbound sulfur. When the activated surface is subsequently immersed in AuCl3 solution, Au NPs are found to preferentially decorate onto the modified regions. As a result, Au NPs can be selectively and locally anchored onto designated regions on the MoS2 surface. With a scanning laser beam, microlandscapes comprising of Au NPs decorated on laser-defined micropatterns are constructed. By varying the laser power, reaction time and thickness of the MoS2 films, the size and density of the NPs can be controlled. The resulting hybrid materials are demonstrated as efficient Raman active surfaces for the detection of aromatic molecules with high sensitivity.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
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24
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Han C, Xiang D, Zheng M, Lin J, Zhong J, Sow CH, Chen W. Tuning the electronic properties of ZnO nanowire field effect transistors via surface functionalization. Nanotechnology 2015; 26:095202. [PMID: 25676393 DOI: 10.1088/0957-4484/26/9/095202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using in situ field effect transistor (FET) characterization combined with the molecular beam epitaxy technique, we demonstrate a significant depletion of electron charge carriers in single zinc oxide (ZnO) nanowire through the surface modification with molybdenum trioxide (MoO3) and 1, 4, 5, 8, 9, 11-hexaazatriphenylene hexacarbonitrile (HATCN) layers. The electron mobility of ZnO nanowire was found to sharply decrease after the surface modification with MoO3; in contrast, the electron mobility significantly increased after functionalization with HATCN layers. Such depletion of n-type conduction originates from the interfacial charge transfer, corroborated by in situ photoelectron spectroscopy studies. The air exposure effect on MoO(3-) and HATCN-coated ZnO nanowire devices was also investigated.
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Deng S, Thomas Cherian C, Liu XL, Tan HR, Yeo LH, Yu X, Rusydi A, Chowdari BVR, Fan HM, Sow CH. Inside Cover: Ultrathin Hexagonal Hybrid Nanosheets Synthesized by Graphene Oxide-Assisted Exfoliation of β-Co(OH) 2Mesocrystals (Chem. Eur. J. 39/2014). Chemistry 2014. [DOI: 10.1002/chem.201490163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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26
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Lu J, Liu H, Zheng M, Zhang H, Lim SX, Tok ES, Sow CH. Laser modified ZnO/CdSSe core-shell nanowire arrays for Micro-Steganography and improved photoconduction. Sci Rep 2014; 4:6350. [PMID: 25213321 PMCID: PMC4161969 DOI: 10.1038/srep06350] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 08/22/2014] [Indexed: 11/09/2022] Open
Abstract
Arrays of ZnO/CdSSe core/shell nanowires with shells of tunable band gaps represent a class of interesting hybrid nanomaterials with unique optical and photoelectrical properties due to their type II heterojunctions and chemical compositions. In this work, we demonstrate that direct focused laser beam irradiation is able to achieve localized modification of the hybrid structure and chemical composition of the nanowire arrays. As a result, the photoresponsivity of the laser modified hybrid is improved by a factor of ~3. A 3D photodetector with improved performance is demonstrated using laser modified nanowire arrays overlaid with monolayer graphene as the top electrode. Finally, by controlling the power of the scanning focused laser beam, micropatterns with different fluorescence emissions are created on a substrate covered with nanowire arrays. Such a pattern is not apparent when imaged under normal optical microscopy but the pattern becomes readily revealed under fluorescence microscopy i.e. a form of Micro-Steganography is achieved.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Hongwei Liu
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, 117602, Singapore
| | - Minrui Zheng
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Hongji Zhang
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Sharon Xiaodai Lim
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Eng Soon Tok
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
| | - Chorng Haur Sow
- Department of Physics, 2 Science Drive 3, National University of Singapore, 117542, Singapore
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27
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Deng S, Thomas Cherian C, Liu XL, Tan HR, Yeo LH, Yu X, Rusydi A, Chowdari BVR, Fan HM, Sow CH. Ultrathin Hexagonal Hybrid Nanosheets Synthesized by Graphene Oxide-Assisted Exfoliation of β-Co(OH)2Mesocrystals. Chemistry 2014; 20:12444-52. [DOI: 10.1002/chem.201403068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/21/2014] [Indexed: 11/05/2022]
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28
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Lu J, Liu H, Deng S, Zheng M, Wang Y, van Kan JA, Tang SH, Zhang X, Sow CH, Mhaisalkar SG. Highly sensitive and multispectral responsive phototransistor using tungsten-doped VO2 nanowires. Nanoscale 2014; 6:7619-7627. [PMID: 24896423 DOI: 10.1039/c4nr00898g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work, we report a novel and feasible strategy for the practical applications of one-dimensional ultrasensitive phototransistors made of tungsten-doped VO2 single nanowires. The photoconductive response of the single nanowire device was investigated under different visible light excitations (405 nm, 532 nm, and 660 nm). The phototransistor device exhibited ultrafast photoresponse, high responsivity, broad multispectral response, and rapid saturation characteristic curves. These promising results help to promote the applications of this material in nano-scale optoelectronic devices such as efficient multispectral phototransistors and optical switches.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore.
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29
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Lu J, Lu JH, Liu H, Liu B, Chan KX, Lin J, Chen W, Loh KP, Sow CH. Improved photoelectrical properties of MoS(2) films after laser micromachining. ACS Nano 2014; 8:6334-43. [PMID: 24863730 DOI: 10.1021/nn501821z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Direct patterning of ultrathin MoS2 films with well-defined structures and controllable thickness is appealing since the properties of MoS2 sheets are sensitive to the number of layer and surface properties. In this work, we employed a facile, effective, and well-controlled technique to achieve micropatterning of MoS2 films with a focused laser beam. We demonstrated that a direct focused laser beam irradiation was able to achieve localized modification and thinning of as-synthesized MoS2 films. With a scanning laser beam, microdomains with well-defined structures and controllable thickness were created on the same film. We found that laser modification altered the photoelectrical property of the MoS2 films, and subsequently, photodetectors with improved performance have been fabricated and demonstrated using laser modified films.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore
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30
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Azimi S, Dang Z, Zhang C, Song J, Breese MBH, Sow CH, van Kan JA, van der Maarel JRC. Buried centimeter-long micro- and nanochannel arrays in porous silicon and glass. Lab Chip 2014; 14:2081-2089. [PMID: 24793081 DOI: 10.1039/c4lc00062e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We developed a simple process to fabricate deeply buried micro- and nanoscale channels in glass and porous silicon from bulk silicon using a combination of ion beam irradiation, electrochemical anodization and high temperature oxidation. The depth, width and length of these structures can be controllably varied and we successfully fabricated an array of centimeter-long buried micro- and nanochannels. This process allows densely packed, arbitrary-shaped channel geometries with micro- to nanoscale dimensions to be produced in a three-dimensional multilevel architecture, providing a route to fabricate complex devices for use in nanofluidics and lab-on-a-chip systems. We demonstrate the integration of these channels with large reservoirs for DNA linearization in high aspect ratio nanochannels.
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Affiliation(s)
- Sara Azimi
- Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542.
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31
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Teoh HF, Dzung P, Lim WQ, Chua JH, Lee KK, Hu Z, Tan H, Tok ES, Sow CH. Microlandscaping on a graphene oxide film via localized decoration of Ag nanoparticles. Nanoscale 2014; 6:3143-3149. [PMID: 24496439 DOI: 10.1039/c3nr05373c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A direct and facile method for micro-landscaping of Ag nanoparticles on reduced graphene oxide (rGO) is presented. This method employs a focused laser beam to achieve local reduction of Ag(+) ions to Ag NPs by laser irradiation on a GO film that is submerged in AgNO3 solution. Using this method, the Ag nanoparticles can be directly anchored on a rGO film, creating a microlandscape of Ag nanoparticles on the rGO film. In addition, varying the intensity of the laser beam can control the shapes, sizes and distributions of Ag nanoparticles. The resulting hybrid materials exhibit surface enhanced Raman scattering of up to 16 times depending on the size and number density of silver nanoparticles. In addition, the hybrid Ag-rGO material shows superior photoresponse when compared to rGO.
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Affiliation(s)
- Hao Fatt Teoh
- Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore 117456.
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Liu H, Lu J, Tang SH, Sow CH, Zhang X. Composition-dependent electron transport in CdS(x)Se(1-x) nanobelts: a THz spectroscopy study. Opt Lett 2014; 39:567-570. [PMID: 24487867 DOI: 10.1364/ol.39.000567] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a study on the composition-dependent electron transport in ternary CdS(x)Se(1-x) nanobelts at equilibrium and nonequilibrium conditions via THz spectroscopy. The measured spectra are analyzed using a Drude-Smith model combined with a harmonic oscillator. The physical origin of parameters in the Drude-Smith model is studied in detail. Under equilibrium conditions, the surface depletion region is the dominant factor to free-carrier backscattering. However, under nonequilibrium conditions, the influence of the surface depletion region is masked by the high bulk concentration and the free carriers are mainly localized by composition disorder. The contributions from different mechanisms to the carrier mobility are also explored. In equilibrium, alloy scattering is the most vital scattering mechanism for nanobelts with x=0.25→0.9 since composition disorder is significant in this range. On the other hand, the effect of electron-phonon interaction increases under photoexcitation.
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Mukherjee B, Murali G, Lim SX, Zheng M, Tok ES, Sow CH. Direct laser micropatterning of GeSe2 nanostructures film with controlled optoelectrical properties. RSC Adv 2014. [DOI: 10.1039/c3ra46790b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Cherian CT, Sundaramurthy J, Reddy MV, Suresh Kumar P, Mani K, Pliszka D, Sow CH, Ramakrishna S, Chowdari BVR. Morphologically robust NiFe2O4 nanofibers as high capacity Li-ion battery anode material. ACS Appl Mater Interfaces 2013; 5:9957-9963. [PMID: 24099146 DOI: 10.1021/am401779p] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this work, the electrochemical performance of NiFe2O4 nanofibers synthesized by an electrospinning approach have been discussed in detail. Lithium storage properties of nanofibers are evaluated and compared with NiFe2O4 nanoparticles by galvanostatic cycling and cyclic voltammetry studies, both in half-cell configurations. Nanofibers exhibit a higher charge-storage capacity of 1000 mAh g(-1) even after 100 cycles with high Coulmbic efficiency of 100% between 10 and 100 cycles. Ex situ microscopy studies confirmed that cycled nanofiber electrodes maintained the morphology and remained intact even after 100 charge-discharge cycles. The NiFe2O4 nanofiber electrode does not experience any structural stress and eventual pulverisation during lithium cycling and hence provides an efficient electron conducting pathway. The excellent electrochemical performance of NiFe2O4 nanofibers is due to the unique porous morphology of continuous nanofibers.
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Affiliation(s)
- Christie Thomas Cherian
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551
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Mukherjee B, Cai Y, Tan HR, Feng YP, Tok ES, Sow CH. NIR Schottky photodetectors based on individual single-crystalline GeSe nanosheet. ACS Appl Mater Interfaces 2013; 5:9594-604. [PMID: 24028388 DOI: 10.1021/am402550s] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We have synthesized high-quality, micrometer-sized, single-crystal GeSe nanosheets using vapor transport and deposition techniques. Photoresponse is investigated based on mechanically exfoliated GeSe nanosheet combined with Au contacts under a global laser irradiation scheme. The nonlinearship, asymmetric, and unsaturated characteristics of the I-V curves reveal that two uneven back-to-back Schottky contacts are formed. First-principles calculations indicate that the occurrence of defects-induced in-gap defective states, which are responsible for the slow decay of the current in the OFF state and for the weak light intensity dependence of photocurrent. The Schottky photodetector exhibits a marked photoresponse to NIR light illumination (maximum photoconductive gain ∼5.3 × 10(2) % at 4 V) at a wavelength of 808 nm. The significant photoresponse and good responsitivity (∼3.5 A W(-1)) suggests its potential applications as photodetectors.
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Affiliation(s)
- Bablu Mukherjee
- Department of Physics, National University of Singapore (NUS) , 2 Science Drive 3, Singapore 117542
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Cherian CT, Zheng M, Reddy MV, Chowdari BVR, Sow CH. Zn2SnO4 nanowires versus nanoplates: electrochemical performance and morphological evolution during Li-cycling. ACS Appl Mater Interfaces 2013; 5:6054-60. [PMID: 23738585 DOI: 10.1021/am400802j] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Zn2SnO4 nanowires have been synthesized directly on stainless steel substrate without any buffer layers by the vapor transport method. The structural and morphological properties are investigated by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performance of Zn2SnO4 nanowires is examined by galvanostatic cycling and cyclic voltammetry (CV) measurements in two different voltage windows, 0.005-3 and 0.005-1.5 V vs Li and compared to that of Zn2SnO4 nanoplates prepared by hydrothermal method. Galvanostatic cycling studies of Zn2SnO4 nanowires in the voltage range 0.005-3 V, at a current of 120 mA g(-1), show a reversible capacity of 1000 (±5) mAh g(-1) with almost stable capacity for first 10 cycles, which thereafter fades to 695 mAh g(-1) by 60 cycles. Upon cycling in the voltage range 0.005-1.5 V vs Li, a stable, reversible capacity of 680 (±5) mAh g(-1) is observed for first 10 cycles with a capacity retention of 58% between 10-50 cycles. On the other hand, Zn2SnO4 nanoplates show drastic capacity fading up to 10 cycles and then showed a capacity retention of 80% and 70% between 10 and 50 cycles when cycled in the voltage range 0.005-1.5 and 0.005-3 V, respectively. The structural and morphological evolutions during cycling and their implications on the Li-cycling behavior of Zn2SnO4 nanowires are examined. The effect of the choice of voltage range and initial morphology of the active material on the Li-cycleabilty is also elucidated.
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Wei D, Xie L, Lee KK, Hu Z, Tan S, Chen W, Sow CH, Chen K, Liu Y, Wee ATS. Controllable unzipping for intramolecular junctions of graphene nanoribbons and single-walled carbon nanotubes. Nat Commun 2013; 4:1374. [DOI: 10.1038/ncomms2366] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/10/2012] [Indexed: 12/23/2022] Open
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Hu Z, Tok ES, Sow CH. Localized photo-induced voltage with controlled polarity in single K enriched MoO3 nanobundle. Nanotechnology 2012; 23:475204. [PMID: 23117865 DOI: 10.1088/0957-4484/23/47/475204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The photo-induced voltage in an individual K enriched MoO(3) nanobundle was studied with localized focused laser beam irradiation. Without an external bias voltage, a significant photo-induced voltage (36.5 mV) was produced in a single nanobundle under low laser power (2.2 mW). Remarkably, the amplitude and polarity of the voltage could be controlled by the location of the focused laser spot. Unlike the common photo-response that comes from metal-semiconductor junction or PN junction in hybrid nanomaterial, the observed photo-induced effect is from the nanobundle itself, attributed to the small band gap of the material.
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Affiliation(s)
- Zhibin Hu
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
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Pan Y, Deng S, Polavarapu L, Gao N, Yuan P, Sow CH, Xu QH. Plasmon-enhanced photocatalytic properties of Cu2O nanowire-Au nanoparticle assemblies. Langmuir 2012; 28:12304-12310. [PMID: 22813236 DOI: 10.1021/la301813v] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Cu(2)O-Au nanocomposites (NCs) with tunable coverage of Au were prepared by a facile method of mixing gold nanoparticles (Au NPs) with copper(I) oxide nanowires (Cu(2)O NWs) in various ratios. These Cu(2)O-Au NCs display tunable optical properties, and their photocatalytic properties were dependent on the coverage density of Au NPs. The photocatalytic activity of Cu(2)O-Au NCs was examined by photodegradation of methylene blue. The presence of Au NPs enhanced the photodegradation efficiency of Cu(2)O NCs. The photocatalytic efficiency of Cu(2)O-Au NCs initially increased with the increasing coverage density of Au NPs and then decreased as the surface of Cu(2)O became densely covered by Au NPs. The enhanced photocatalytic efficiency was ascribed to enhanced light absorption (by the surface plasmon resonance) and the electron sink effect of the Au NPs.
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Affiliation(s)
- Yanlin Pan
- Department of Chemistry, National University of Singapore, Singapore
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41
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Lee KK, Loh PY, Sow CH, Chin WS. CoOOH nanosheet electrodes: Simple fabrication for sensitive electrochemical sensing of hydrogen peroxide and hydrazine. Biosens Bioelectron 2012; 39:255-60. [PMID: 22898661 DOI: 10.1016/j.bios.2012.07.061] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 02/08/2023]
Abstract
Cobalt oxyhydroxide, CoOOH, nanosheets were prepared via a surface alkaline treatment of cobalt foil at room temperature without using templates and catalysts. The morphology, chemical composition and structures of the nanosheets were characterized by XRD, FTIR and Raman spectroscopy, FESEM and TEM. These oriented and nanostructured arrays can be used directly as electrodes, thus simplifying the electrode fabrication process, as well as offering advantages such as enhanced electrode-electrolyte contact area, minimum diffusion resistance and direct active material-current collector connection for fast electron transport. The electrode was used as an electrochemical sensor towards non-enzymatic detection of hydrogen peroxide and hydrazine in alkaline solution. The amperometric detection of H(2)O(2) and N(2)H(4) was carried out at low potential (0V and 0.1V). At 0.1V, the amperometric signals are linearly proportional to H(2)O(2) concentration up to 1.6mM (R(2)=0.995), showing a detection limit (S/N=3) of 40μM and a high sensitivity of 99μA mM(-1)cm(-2). For N(2)H(4), the amperometric signals are linearly proportional to concentration up to 1.2mM (R(2)=0.99), showing a detection limit (S/N=3) of 20μM and a high sensitivity of 155μA mM(-1)cm(-2) at 0.1V.
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Affiliation(s)
- Kian Keat Lee
- NUS Nanoscience and Nanotechnology Initiative, Block S13, 2 Science Drive 3, Singapore 117542, Singapore.
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Lee KK, Deng S, Fan HM, Mhaisalkar S, Tan HR, Tok ES, Loh KP, Chin WS, Sow CH. α-Fe2O3 nanotubes-reduced graphene oxide composites as synergistic electrochemical capacitor materials. Nanoscale 2012; 4:2958-61. [PMID: 22441701 DOI: 10.1039/c2nr11902a] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We present a facile approach for the fabrication of a nanocomposite comprising α-Fe(2)O(3) nanotubes (NTs) anchored on reduced graphene oxide (rGO) for electrochemical capacitors (ECs). The hollow tubular structure of the α-Fe(2)O(3) NTs presents a high surface area for reaction, while the incorporation of rGO provides an efficient two-dimensional conductive pathway to allow fast, reversible redox reaction. As a result, the nanocomposite materials exhibit a specific capacitance which is remarkably higher (~7 times) than α-Fe(2)O(3) NTs alone. In addition, the nanocomposites show excellent cycling life and large negative potential window. These findings suggest that such nanocomposites are a promising candidate as negative electrodes in asymmetrical capacitors with neutral electrolytes.
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Affiliation(s)
- K K Lee
- NUS Nanoscience and Nanotechnology Initiative, Block S13, 2 Science Drive 3, Singapore 117542
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Bui CT, Xie R, Zheng M, Zhang Q, Sow CH, Li B, Thong JTL. Diameter-dependent thermal transport in individual ZnO nanowires and its correlation with surface coating and defects. Small 2012; 8:738-745. [PMID: 22162412 DOI: 10.1002/smll.201102046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Indexed: 05/31/2023]
Abstract
A systematic study of the thermal transport properties of individual single-crystal zinc oxide (ZnO) nanowires (NWs) with diameters in the range of ∼50-210 nm is presented. The thermal conductivity of the NWs is found to be dramatically reduced by at least an order of magnitude compared to bulk values, due to enhanced phonon-boundary scattering with a reduction in sample size. While the conventional phonon transport model can qualitatively explain the temperature dependence, it fails to account for the diameter dependence. An empirical relationship for assessing diameter-dependent thermal properties is observed, which shows an approximately linear dependence of the thermal conductivity on the cross-sectional area of the NWs in the measured diameter range. Furthermore, it is found that an amorphous-carbon layer coating on the NWs does not perturb the thermal properties of the NW cores, whereas 30 keV Ga(+) ion irradiation at low dose (∼4 × 10(14) cm(-2)) leads to a remarkable reduction of the thermal conductivity of the ZnO NWs.
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Affiliation(s)
- Cong Tinh Bui
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 117456, Republic of Singapore
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Cherian CT, Reddy MV, Rao GVS, Sow CH, Chowdari BVR. Li-cycling properties of nano-crystalline (Ni1 − x Zn x )Fe2O4 (0 ≤ x ≤ 1). J Solid State Electrochem 2012. [DOI: 10.1007/s10008-012-1662-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Deng S, Tjoa V, Fan HM, Tan HR, Sayle DC, Olivo M, Mhaisalkar S, Wei J, Sow CH. Reduced graphene oxide conjugated Cu2O nanowire mesocrystals for high-performance NO2 gas sensor. J Am Chem Soc 2012; 134:4905-17. [PMID: 22332949 DOI: 10.1021/ja211683m] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reduced graphene oxide (rGO)-conjugated Cu(2)O nanowire mesocrystals were formed by nonclassical crystallization in the presence of GO and o-anisidine under hydrothermal conditions. The resultant mesocrystals are comprised of highly anisotropic nanowires as building blocks and possess a distinct octahedral morphology with eight {111} equivalent crystal faces. The mechanisms underlying the sequential formation of the mesocrystals are as follows: first, GO-promoted agglomeration of amorphous spherical Cu(2)O nanoparticles at the initial stage, leading to the transition of growth mechanism from conventional ion-by-ion growth to particle-mediated crystallization; second, the evolution of the amorphous microspheres into hierarchical structure, and finally to nanowire mesocrystals through mesoscale transformation, where Ostwald ripening is responsible for the growth of the nanowire building blocks; third, large-scale self-organization of the mesocrystals and the reduction of GO (at high GO concentration) occur simultaneously, resulting in an integrated hybrid architecture where porous three-dimensional (3D) framework structures interspersed among two-dimensional (2D) rGO sheets. Interestingly, "super-mesocrystals" formed by 3D oriented attachment of mesocrystals are also formed judging from the voided Sierpinski polyhedrons observed. Furthermore, the interior nanowire architecture of these mesocrystals can be kinetically controlled by careful variation of growth conditions. Owing to high specific surface area and improved conductivity, the rGO-Cu(2)O mesocrystals achieved a higher sensitivity toward NO(2) at room temperature, surpassing the performance of standalone systems of Cu(2)O nanowires networks and rGO sheets. The unique characteristics of rGO-Cu(2)O mesocrystal point to its promising applications in ultrasensitive environmental sensors.
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Affiliation(s)
- Suzi Deng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
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Lu J, Liu H, Sun C, Zheng M, Nripan M, Chen GS, Subodh GM, Zhang X, Sow CH. Optical and electrical applications of ZnS(x)Se(1-x) nanowires-network with uniform and controllable stoichiometry. Nanoscale 2012; 4:976-981. [PMID: 22234311 DOI: 10.1039/c2nr11459c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Single crystalline ternary ZnS(x)Se(1-x) nanowires with uniform chemical stoichiometry and accurately controllable compositions (0≤x≤ 1) were synthesized through a simple and yet effective one-step approach with a specially designed modification. Energy-gap-tuning via compositional change was achieved for a direct band gap from 2.6 to 3.6 eV. Raman spectroscopy studies revealed typical two-mode behavior indicative of high miscibility in the alloyed compound. Moreover, the enhanced electrical-conductivity and gating effect behavior after the formation of ternary alloy enable their application in nano/micro-field effect transistor devices. In addition, the slow recombination rate in the photo-response process indicates their potential for photoelectric applications.
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Affiliation(s)
- Junpeng Lu
- Department of Physics, National University of Singapore (NUS), 2 Science Drive 3, 117542, Singapore
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Cherian CT, Sundaramurthy J, Kalaivani M, Ragupathy P, Kumar PS, Thavasi V, Reddy MV, Sow CH, Mhaisalkar SG, Ramakrishna S, Chowdari BVR. Electrospun α-Fe2O3 nanorods as a stable, high capacity anode material for Li-ion batteries. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31053h] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Prabhakar RR, Mathews N, Jinesh KB, Karthik KRG, Pramana SS, Varghese B, Sow CH, Mhaisalkar S. Efficient multispectral photodetection using Mn doped ZnO nanowires. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm16698d] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Prabhakar RR, Pramana SS, Karthik KRG, Sow CH, Jinesh KB. Ultra-thin conformal deposition of CuInS2 on ZnO nanowires by chemical spray pyrolysis. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm31270k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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