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Wong CH, Yeung YM, Zhao X, Law WC, Tang CY, Mak CL, Leung CW, Shi L, Lortz R. A Simulation of the Effect of External and Internal Parameters on the Synthesis of a Carbyne with More than 6000 Atoms for Emerging Continuously Tunable Energy Barriers in CNT-Based Transistors. Nanomaterials (Basel) 2023; 13:1048. [PMID: 36985943 PMCID: PMC10058369 DOI: 10.3390/nano13061048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 06/18/2023]
Abstract
Transistors made up of carbon nanotube CNT have demonstrated excellent current-voltage characteristics which outperform some high-grade silicon-based transistors. A continuously tunable energy barrier across semiconductor interfaces is desired to make the CNT-based transistors more robust. Despite that the direct band gap of the carbyne inside a CNT can be widely tuned by strain, the size of the carbyne cannot be controlled easily. The production of a monoatomic chain with more than 6000 carbon atoms is an enormous technological challenge. To predict the optimal chain length of a carbyne in different molecular environments, we have developed a Monte Carlo model in which a finite-length carbyne with a size of 4000-15,000 atoms is encapsulated by a CNT at finite temperatures. Our simulation shows that the stability of the carbyne@nanotube is strongly influenced by the nature and porosity of the CNT, the external pressure, the temperature, and the chain length. We have observed an initiation of the chain-breaking process in a compressed carbyne@nanotube. Our work provides much-needed input for optimizing the carbyne length to produce carbon chains much longer than 6000 atoms at ~300 K. Design rules are proposed for synthesizing ~1% strained carbyne@(6,5)CNT as a component in CNT-based transistors to tune the energy barriers continuously.
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Affiliation(s)
- Chi Ho Wong
- Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
- Research Institute for Advanced Manufacturing, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Yan Ming Yeung
- School of Science, The Hong Kong University of Science and Technology, Hong Kong 999077, China
| | - Xin Zhao
- Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Wing Cheung Law
- Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Chak Yin Tang
- Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Lei Shi
- State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Rolf Lortz
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong 999077, China
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2
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Zhang Z, Tang Y, Ying Y, Guo J, Gan M, Jiang Y, Xing C, Pan S, Xu M, Zhou Y, Zhang H, Leung CW, Huang H, Mak CL, Fei L. Multistep nucleation visualized during solid-state crystallization. Mater Horiz 2022; 9:1670-1678. [PMID: 35470363 DOI: 10.1039/d2mh00174h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mechanisms of nucleation have been debated for more than a century, despite successes of classical nucleation theory. The nucleation process has been recently argued as involving a nonclassical mechanism (the "two-step" mechanism) in which an intermediate step occurs before the formation of a nascent ordered phase. However, a thorough understanding of this mechanism, in terms of both microscopic kinetics and thermodynamics, remains experimentally challenging. Here, in situ observations using transmission electron microscopy on a solid-state nucleation case indicate that early-stage crystallization can follow the non-classical pathway, yet proceed via a more complex manner in which multiple metastable states precede the emergence of a stable nucleus. The intermediate steps were sequentially isolated as spinodal decomposition of amorphous precursor, mass transport and structural oscillations between crystalline and amorphous states. Our experimental and theoretical analyses support the idea that the energetic favorability is the driving force for the observed sequence of events. Due to the broad applicability of solid-state crystallization, the findings of this study offer new insights into modern nucleation theory and a potential avenue for materials design.
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Affiliation(s)
- Zhouyang Zhang
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
| | - Yujie Tang
- Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
| | - Yiran Ying
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Junqing Guo
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
| | - Min Gan
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
| | - Yateng Jiang
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
| | - Chunxian Xing
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
- Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
| | - Shanshan Pan
- Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
| | - Ming Xu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Yangbo Zhou
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
| | - Haitao Zhang
- Beijing Key Laboratory of Ionic Liquids Clean Process, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Haitao Huang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Linfeng Fei
- School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials, Jiangxi Engineering Laboratory for Advanced Functional Thin Films and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi 330031, China.
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3
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Zhang Z, Qiang J, Wang S, Xu M, Gan M, Rao Z, Tian T, Ke S, Zhou Y, Hu Y, Leung CW, Mak CL, Fei L. Visualization of Bubble Nucleation and Growth Confined in 2D Flakes. Small 2021; 17:e2103301. [PMID: 34473395 DOI: 10.1002/smll.202103301] [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] [Received: 06/06/2021] [Revised: 07/20/2021] [Indexed: 06/13/2023]
Abstract
The nucleation and growth of bubbles within a solid matrix is a ubiquitous phenomenon that affects many natural and synthetic processes. However, such a bubbling process is almost "invisible" to common characterization methods because it has an intrinsically multiphased nature and occurs on very short time/length scales. Using in situ transmission electron microscopy to explore the decomposition of a solid precursor that emits gaseous byproducts, the direct observation of a complete nanoscale bubbling process confined in ultrathin 2D flakes is presented here. This result suggests a three-step pathway for bubble formation in the confined environment: void formation via spinodal decomposition, bubble nucleation from the spherization of voids, and bubble growth by coalescence. Furthermore, the systematic kinetics analysis based on COMSOL simulations shows that bubble growth is actually achieved by developing metastable or unstable necks between neighboring bubbles before coalescing into one. This thorough understanding of the bubbling mechanism in a confined geometry has implications for refining modern nucleation theories and controlling bubble-related processes in the fabrication of advanced materials (i.e., topological porous materials).
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Affiliation(s)
- Zhouyang Zhang
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Jun Qiang
- State Key Laboratory of High-Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan, 410083, China
| | - Shensong Wang
- Hubei Key Laboratory of Ferro- & Piezoelectric Materials and Devices, School of Microelectronics, Hubei University, Wuhan, Hubei, 430062, China
| | - Ming Xu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Min Gan
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Zhenggang Rao
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Tingfang Tian
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Shanming Ke
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Yangbo Zhou
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
| | - Yongming Hu
- Hubei Key Laboratory of Ferro- & Piezoelectric Materials and Devices, School of Microelectronics, Hubei University, Wuhan, Hubei, 430062, China
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Linfeng Fei
- School of Materials Science and Engineering, Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Key Laboratory for Multiscale Interdisciplinary Study, Nanchang University, Nanchang, Jiangxi, 330031, China
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Wong HF, Ng SM, Zhang W, Liu YK, Wong PKJ, Tang CS, Lam KK, Zhao XW, Meng ZG, Fei LF, Cheng WF, Nordheim DV, Wong WY, Wang ZR, Ploss B, Dai JY, Mak CL, Wee ATS, Leung CW. Modulating Magnetism in Ferroelectric Polymer-Gated Perovskite Manganite Films with Moderate Gate Pulse Chains. ACS Appl Mater Interfaces 2020; 12:56541-56548. [PMID: 33283518 DOI: 10.1021/acsami.0c14172] [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: 06/12/2023]
Abstract
Most previous attempts on achieving electric-field manipulation of ferromagnetism in complex oxides, such as La0.66Sr0.33MnO3 (LSMO), are based on electrostatically induced charge carrier changes through high-k dielectrics or ferroelectrics. Here, the use of a ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene [P(VDF-TrFE)], as a gate dielectric to successfully modulate the ferromagnetism of the LSMO thin film in a field-effect device geometry is demonstrated. Specifically, through the application of low-voltage pulse chains inadequate to switch the electric dipoles of the copolymer, enhanced tunability of the oxide magnetic response is obtained, compared to that induced by ferroelectric polarization. Such observations have been attributed to electric field-induced oxygen vacancy accumulation/depletion in the LSMO layer upon the application of pulse chains, which is supported by surface-sensitive-characterization techniques, including X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. These techniques not only unveil the electrochemical nature of the mechanism but also establish a direct correlation between the oxygen vacancies created and subsequent changes to the valence states of Mn ions in LSMO. These demonstrations based on the pulsing strategy can be a viable route equally applicable to other functional oxides for the construction of electric field-controlled magnetic devices.
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Affiliation(s)
- Hon Fai Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wen Zhang
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Yu Kuai Liu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Ping Kwan Johnny Wong
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Sin Tang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Ka Kin Lam
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Xu Wen Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zhen Gong Meng
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lin Feng Fei
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wang Fai Cheng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Danny von Nordheim
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Wai Yeung Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zong Rong Wang
- State Key Lab of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Bernd Ploss
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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5
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Lam KK, Ng SM, Wong HF, Fei L, Liu Y, Chan KH, Ye H, Leung CW, Mak CL. Effect of Thickness on the Optical and Electrical Properties of ITO/Au/ITO Sandwich Structures. ACS Appl Mater Interfaces 2020; 12:13437-13446. [PMID: 32088951 DOI: 10.1021/acsami.9b20203] [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: 06/10/2023]
Abstract
Tin-doped indium oxide (ITO)/Au/ITO sandwich structures with varying top and bottom ITO film thicknesses were deposited by magnetron sputtering. The effects of varying thickness of the two ITO films on the structural, electrical, and optical properties of the sandwich structures were investigated. X-ray diffraction spectra showed that by inserting an ultrathin Au film, the average grain size of the top ITO layer was significantly increased, but not for the bottom one. The optical properties of the sandwich structures were measured by transmittance measurement and spectroscopic ellipsometry. In the symmetric structure, where the top and the bottom ITO layers had the same thickness, we demonstrated that the crossover wavelength can be changed from the visible range (830 nm) to the near-infrared range (1490 nm) by increasing the top as well as bottom ITO thickness, corresponding to a plasmonic tuning ability of over 600 nm. The evaluation of this trilayer structure as a plasmonic device was asserted based on three quality factors. A comparison of the performance of this trilayer structure with conventional materials was also discussed.
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Affiliation(s)
- Ka Kin Lam
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Hon Fai Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Linfeng Fei
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Yukuai Liu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Ka Ho Chan
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Hui Ye
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou 310027, P. R. China
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR, China
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Liu Y, Ying Y, Fei L, Liu Y, Hu Q, Zhang G, Pang SY, Lu W, Mak CL, Luo X, Zhou L, Wei M, Huang H. Valence Engineering via Selective Atomic Substitution on Tetrahedral Sites in Spinel Oxide for Highly Enhanced Oxygen Evolution Catalysis. J Am Chem Soc 2019; 141:8136-8145. [PMID: 31017412 DOI: 10.1021/jacs.8b13701] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A major challenge that prohibits the practical application of single/double-transition metal (3d-M) oxides as oxygen evolution reaction (OER) catalysts is the high overpotentials during the electrochemical process. Herein, our theoretical calculation shows that Fe will be more energetically favorable in the tetrahedral site than Ni and Co, which can further regulate their electronic structure of binary NiCo spinel oxides for optimal adsorption energies of OER intermediates and improved electronic conductivity and hence boost their OER performance. X-ray absorption spectroscopy study on the as-synthesized NiCoFe oxide catalysts indicates that Fe preferentially dopes into tetrahedral sites of the lattice, which induces high proportions of Ni3+ and Co2+ on the octahedral sites (the active sites in OER). Consequently, this material exhibits a significantly enhanced OER performance with an ultralow overpotential of 201 mV cm-2 at 10 mA cm-2 and a small Tafel slope of 39 mV dec-1, which are much superior to state-of-the-art Ni-Co based catalysts.
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Affiliation(s)
- Yan Liu
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Yiran Ying
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Linfeng Fei
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Yi Liu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , P. R. China
| | - Qingzhao Hu
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Guoge Zhang
- School of Materials Science and Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Sin Yi Pang
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Wei Lu
- University Research Facility in Materials Characterization and Device Fabrication , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Chee Leung Mak
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Xin Luo
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Limin Zhou
- Department of Mechanical Engineering , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
| | - Mingdeng Wei
- Institute of Advanced Energy Materials , Fuzhou University , Fuzhou 350002 , P. R. China
| | - Haitao Huang
- Department of Applied Physics , The Hong Kong Polytechnic University , Hung Hom, Kowloon , Hong Kong , China
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Fei L, Xu M, Jiang J, Ng SM, Shu L, Sun L, Xie K, Huang H, Leung CW, Mak CL, Wang Y. Three-dimensional macroporous graphene monoliths with entrapped MoS2nanoflakes from single-step synthesis for high-performance sodium-ion batteries. RSC Adv 2018; 8:2477-2484. [PMID: 35541460 PMCID: PMC9077459 DOI: 10.1039/c7ra12617d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 12/30/2017] [Indexed: 01/24/2023] Open
Abstract
Layered metal sulfides (MoS2, WS2, SnS2, and SnS) offer high potential as advanced anode materials in sodium ion batteries upon integration with highly-conductive graphene materials. However, in addition to being costly and time-consuming, existing strategies for synthesizing sulfides/graphene composites often involve complicated procedures. It is therefore essential to develop a simple yet scalable pathway to construct sulfide/graphene composites for practical applications. Here, we highlight a one-step, template-free, high-throughput “self-bubbling” method for producing MoS2/graphene composites, which is suitable for large-scale production of sulfide/graphene composites. The final product featured MoS2 nanoflakes distributed in three-dimensional macroporous monolithic graphene. Moreover, this unique MoS2/graphene composite achieved remarkable electrochemical performance when being applied to Na-ion battery anodes; namely, excellent cycling stability (474 mA h g−1 at 0.1 A g−1 after 100 cycles) and high rate capability (406 mA h g−1 at 0.25 A g−1 and 359 mA h g−1 at 0.5 A g−1). This self-bubbling approach should be applicable to delivering other graphene-based composites for emerging applications such as energy storage, catalysis, and sensing. A single-step, template-free, high-throughput synthesis method is developed to produce graphene/MoS2 composites for improved performances in sodium-ion batteries.![]()
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Affiliation(s)
- Linfeng Fei
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
| | - Ming Xu
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
- School of Metallurgical and Environment
- Central South University
| | - Juan Jiang
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials
- Hubei University
| | - Sheung Mei Ng
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
| | - Longlong Shu
- School of Materials Science and Engineering
- Nanchang University
- Nanchang
- China
| | - Li Sun
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes
- National Laboratory of Mineral Materials
- School of Materials Science and Technology
- China University of Geosciences
- Beijing 100083
| | - Keyu Xie
- State Key Laboratory of Solidification Processing
- Center for Nano Energy Materials
- Northwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene (NPU)
- Xi'an 710072
- China
| | - Haitao Huang
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
| | - Chi Wah Leung
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
| | - Chee Leung Mak
- Department of Applied Physics
- The Hong Kong Polytechnic University
- China
| | - Yu Wang
- School of Materials Science and Engineering
- Nanchang University
- Nanchang
- China
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8
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Fei L, Ng SM, Lu W, Xu M, Shu L, Zhang WB, Yong Z, Sun T, Lam CH, Leung CW, Mak CL, Wang Y. Atomic-Scale Mechanism on Nucleation and Growth of Mo 2C Nanoparticles Revealed by in Situ Transmission Electron Microscopy. Nano Lett 2016; 16:7875-7881. [PMID: 27960485 DOI: 10.1021/acs.nanolett.6b04160] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [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
With a similar electronic structure as that of platinum, molybdenum carbide (Mo2C) holds significant potential as a high performance catalyst across many chemical reactions. Empirically, the precise control of particle size, shape, and surface nature during synthesis largely determines the catalytic performance of nanoparticles, giving rise to the need of clarifying the underlying growth characteristics in the nucleation and growth of Mo2C. However, the high-temperature annealing involved during the growth of carbides makes it difficult to directly observe and understand the nucleation and growth processes. Here, we report on the use of advanced in situ transmission electron microscopy with atomic resolution to reveal a three-stage mechanism during the growth of Mo2C nanoparticles over a wide temperature range: initial nucleation via a mechanism consistent with spinodal decomposition, subsequent particle coalescence and monomer attachment, and final surface faceting to well-defined particles with minimum surface energy. These microscopic observations made under a heating atmosphere offer new perspectives toward the design of carbide-based catalysts, as well as the tuning of their catalytic performances.
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Affiliation(s)
- Linfeng Fei
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Wei Lu
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Ming Xu
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Longlong Shu
- School of Materials Science and Engineering, Nanchang University , Nanchang, Jiangxi 330031, China
| | - Wei-Bing Zhang
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Zehui Yong
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Tieyu Sun
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Chi Hang Lam
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Yu Wang
- School of Materials Science and Engineering, Nanchang University , Nanchang, Jiangxi 330031, China
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Fang X, Mak CL, Zhang S, Wang Z, Yuan W, Ye H. Pulsed laser deposited indium tin oxides as alternatives to noble metals in the near-infrared region. J Phys Condens Matter 2016; 28:224009. [PMID: 27054885 DOI: 10.1088/0953-8984/28/22/224009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Transparent conductive indium tin oxide thin films with thickness around 200 nm were deposited on glass substrates by pulsed laser deposition technology. The microstructure and the electrical and optical properties of the ITO films deposited under different oxygen pressures and substrate temperatures were systematically investigated. Distinct different x-ray diffraction patterns revealed that the crystallinity of ITO films was highly influenced by deposition conditions. The highest carrier concentration of the ITO films was obtained as 1.34 × 10(21) cm(-3) with the lowest corresponding resistivity of 2.41 × 10(-4) Ω cm. Spectroscopic ellipsometry was applied to retrieve the dielectric permittivity of the ITO films to estimate their potential as plasmonic materials in the near-infrared region. The crossover wavelength (the wavelength where the real part of the permittivity changes from positive to negative) of the ITO films exhibited high dependence on the deposition conditions and was optimized to as low as 1270 nm. Compared with noble metals (silver or gold etc), the lower imaginary part of the permittivity (<3) of ITO films suggests the potential application of ITO in the near-infrared range.
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Affiliation(s)
- Xu Fang
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, People's Republic of China
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Zhang M, Liao C, Mak CH, You P, Mak CL, Yan F. Highly sensitive glucose sensors based on enzyme-modified whole-graphene solution-gated transistors. Sci Rep 2015; 5:8311. [PMID: 25655666 PMCID: PMC4319171 DOI: 10.1038/srep08311] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/08/2015] [Indexed: 01/23/2023] Open
Abstract
Noninvasive glucose detections are convenient techniques for the diagnosis of diabetes mellitus, which require high performance glucose sensors. However, conventional electrochemical glucose sensors are not sensitive enough for these applications. Here, highly sensitive glucose sensors are successfully realized based on whole-graphene solution-gated transistors with the graphene gate electrodes modified with an enzyme glucose oxidase. The sensitivity of the devices is dramatically improved by co-modifying the graphene gates with Pt nanoparticles due to the enhanced electrocatalytic activity of the electrodes. The sensing mechanism is attributed to the reaction of H2O2 generated by the oxidation of glucose near the gate. The optimized glucose sensors show the detection limits down to 0.5 μM and good selectivity, which are sensitive enough for non-invasive glucose detections in body fluids. The devices show the transconductances two orders of magnitude higher than that of a conventional silicon field effect transistor, which is the main reason for their high sensitivity. Moreover, the devices can be conveniently fabricated with low cost. Therefore, the whole-graphene solution-gated transistors are a high-performance sensing platform for not only glucose detections but also many other types of biosensors that may find practical applications in the near future.
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Affiliation(s)
- Meng Zhang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
| | - Caizhi Liao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
| | - Chun Hin Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
| | - Peng You
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
| | - Feng Yan
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong
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Fang X, Mak CL, Dai J, Li K, Ye H, Leung CW. ITO/Au/ITO sandwich structure for near-infrared plasmonics. ACS Appl Mater Interfaces 2014; 6:15743-15752. [PMID: 25167805 DOI: 10.1021/am5026165] [Citation(s) in RCA: 6] [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] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
ITO/Au/ITO trilayers with varying gold spacer layer thicknesses were deposited on glass substrates by pulsed laser deposition. Transmission electron microscopy measurements demonstrated the continuous nature of the Au layer down to 2.4 nm. XRD patterns clearly showed an enhanced crystallinity of the ITO films promoted by the insertion of the gold layer. Compared with a single layer of ITO with a carrier concentration of 7.12 × 10(20) cm(-3), the ITO/Au/ITO structure achieved an effective carrier concentration as high as 3.26 × 10(22) cm(-3). Transmittance and ellipsometry measurements showed that the optical properties of ITO/Au/ITO films were greatly influenced by the thickness of the inserted gold layer. The cross-point wavelength of the trilayer samples was reduced with increasing gold layer thickness. Importantly, the trilayer structure exhibited a reduced loss (compared with plain Au) in the near-infrared region, suggesting its potential for plasmonic applications in the near-infrared range.
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Affiliation(s)
- Xu Fang
- State Key Laboratory of Modern Optical Instrumentation, Department of Optical Engineering, Zhejiang University , Hangzhou, 310027, P. R. China
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Zhang Y, Hao J, Mak CL, Wei X. Effects of site substitutions and concentration on upconversion luminescence of Er(3+)-doped perovskite titanate. Opt Express 2011; 19:1824-1829. [PMID: 21368996 DOI: 10.1364/oe.19.001824] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Upconversion photoluminescence (PL) of Er(3+)-doped BaTiO3 (BTO) with perovskite ABO3 structure is studied in terms of Er3+ substitutions for Ba (A-) and Ti (B-site) with different Er3+ doping concentrations. PL quenching with an increase Er3+ doping concentration is investigated based on the structural change and energy transfer of cross-relaxation process in BTO: Er, i.e. (2)H(11/2) + (4)I(15/2) → (4)I(9/2) + (4)I(13/2). Temperature dependence of the PL in BTO: Er is revealed, which is associated with phase transitions of BTO host. The results imply that the emission from substituted Er3+ ions may be used as a structural probe for the ferroelectric titanates.
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Affiliation(s)
- Yang Zhang
- Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hong Kong
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Liu WC, Mak CL, Wong KH. Thermo-optic properties of epitaxial Sr0.6Ba0.4Nb2O6 waveguides and their application as optical modulator. Opt Express 2009; 17:13677-13684. [PMID: 19654776 DOI: 10.1364/oe.17.013677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A prism-coupler technique was introduced to determine the refractive indices and thermo-optic coefficients of epitaxial Sr(0.6)Ba(0.4)Nb(2)O(6) (SBN) waveguides, in a temperature range covering the ferroelectric-paraelectric phase transition. A strong enhancement in the TO coefficient is observed near T(c). This strong enhancement is related to the critical change of the polarization. The values of dn(e)/dT are significantly larger than dn(o)/dT due to the larger quadratic electro-optic coefficient in TM polarization. In TM mode, the refractive index of SBN is increased by 1.3% as the temperature is increased to 160 degrees C. Our results suggest that SBN waveguide is a potential candidate for thermo-optic modulators and switches.
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Affiliation(s)
- Wen Chao Liu
- Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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Lu SG, Mak CL, Pang GKH, Wong KH, Cheah KW. Blue-shift and intensity enhancement of photoluminescence in lead-zirconate-titanate-doped silica nanocomposites. Nanotechnology 2008; 19:035702. [PMID: 21817587 DOI: 10.1088/0957-4484/19/03/035702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Transparent PbZr(0.52)Ti(0.48)O(3) (PZT)-doped silica nanocomposites were fabricated via a modified sol-gel process. The nanocomposites were annealed at different temperatures between 740 and 800 °C in order to produce PZT crystallites with different particle sizes. X-ray diffraction analysis indicated that the embedded PZT nanoparticles were crystallized with a perovskite structure while the SiO(2) matrix was still in an amorphous state. Transmission electron microscopy confirmed that the PZT particles were of nanosize with perovskite structure and dispersed within the SiO(2) matrix. Photoluminescence spectra of the samples were measured between 10 and 290 K. The pure silica matrix showed an emission band at 3.20 eV and a weak emission band at 2.65 eV. They were noticeably suppressed in the PZT/SiO(2) nanocomposites. An additional emission band at ∼2.30 eV, due to transition within the PZT crystallites, was identified. This emission band showed a large blue-shift with decreasing PZT crystallite size and a substantially enhanced intensity as compared with that of bulk PZT ceramics. Our studies demonstrate the typical quantum size effect of ferroelectric-doped nanocomposites and the large influence of the silica matrix on the PL intensity of the embedded PZT particles.
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Affiliation(s)
- S G Lu
- Department of Applied Physics and Materials Research Centre, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
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Li XZ, Liu HL, Li FB, Mak CL. Photoelectrocatalytic oxidation of rhodamine B in aqueous solution using Ti/TiO2 mesh photoelectrodes. J Environ Sci Health A Tox Hazard Subst Environ Eng 2002; 37:55-69. [PMID: 11846269 DOI: 10.1081/ese-100108482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To further improve the photooxidation techniques for water and waste-water purification, a Ti/TiO2 mesh electrode, was successfully prepared by anodizing Ti mesh in 0.5M H2SO4 solution. The structural and surface morphology of the Ti/TiO2 electrode was examined by Raman spectroscopy and scanning electronic microscopy (SEM) respectively. The examination results indicated that its structure and properties were affected by its growth rate in the anodization process, and anatase TiO2 was dominant in its composition. The photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation of rhodamine B in aqueous solution using the Ti/TiO2 electrode were investigated and compared. The experimental results demonstrated that the PEC oxidation by applying an electrical bias between the Ti/TiO2 electrode and Pt electrode could significantly enhance the degradation rate of rhodamine B compared with the PC oxidation. It was found that the best performance of PEC oxidation was achieved by applying the electrical bias of 0.6 V. The mechanism of rhodamine B degradation in the PEC process was discussed by studying the changes of absorbance spectrum and proton nuclear magnetic resonance spectroscopy of rhodamine B during the PEC degradation. The experimental results illustrated that both de-ethylation and chromogen destruction of rhodamine B under UV-light irradiation in the PEC degradation took place simultaneously.
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Affiliation(s)
- X Z Li
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon.
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Mak CL, Sooryakumar R, Steiner MM, Jonker BT. Optical transitions in Zn1-xCoxSe and Zn1-xFexSe: Strong concentration-dependent effective p-d exchange. Phys Rev B Condens Matter 1993; 48:11743-11751. [PMID: 10007510 DOI: 10.1103/physrevb.48.11743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Mak CL, Sooryakumar R, Jonker BT, Prinz GA. Vibrational modes in Zn1-xFexSe and Zn1-xCoxSe. Phys Rev B Condens Matter 1992; 45:3344-3348. [PMID: 10001906 DOI: 10.1103/physrevb.45.3344] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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