58 results on '"Weiya Zhou"'
Search Results
2. Preparing high-concentration individualized carbon nanotubes for industrial separation of multiple single-chirality species
- Author
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Dehua Yang, Linhai Li, Xiao Li, Wei Xi, Yuejuan Zhang, Yumin Liu, Xiaojun Wei, Weiya Zhou, Fei Wei, Sishen Xie, and Huaping Liu
- Subjects
Multidisciplinary ,General Physics and Astronomy ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology - Abstract
Industrial production of single-chirality carbon nanotubes is critical for their applications in high-speed and low-power nanoelectronic devices, but both their growth and separation have been major challenges. Here, we report a method for industrial separation of single-chirality carbon nanotubes from a variety of raw materials with gel chromatography by increasing the concentration of carbon nanotube solution. The high-concentration individualized carbon nanotube solution is prepared by ultrasonic dispersion followed by centrifugation and ultrasonic redispersion. With this technique, the concentration of the as-prepared individualized carbon nanotubes is increased from about 0.19 mg/mL to approximately 1 mg/mL, and the separation yield of multiple single-chirality species is increased by approximately six times to the milligram scale in one separation run with gel chromatography. When the dispersion technique is applied to an inexpensive hybrid of graphene and carbon nanotubes with a wide diameter range of 0.8–2.0 nm, and the separation yield of single-chirality species is increased by more than an order of magnitude to the sub-milligram scale. Moreover, with present separation technique, the environmental impact and cost of producing single-chirality species are greatly reduced. We anticipate that this method promotes industrial production and practical applications of single-chirality carbon nanotubes in carbon-based integration circuits.
- Published
- 2023
3. Chirality-dependent electrical transport properties of carbon nanotubes obtained by experimental measurement
- Author
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Wei Su, Xiao Li, Linhai Li, Dehua Yang, Futian Wang, Xiaojun Wei, Weiya Zhou, Hiromichi Kataura, Sishen Xie, and Huaping Liu
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Multidisciplinary ,General Physics and Astronomy ,General Chemistry ,General Biochemistry, Genetics and Molecular Biology - Abstract
Establishing the relationship between the electrical transport properties of single-wall carbon nanotubes (SWCNTs) and their structures is critical for the design of high-performance SWCNT-based electronic and optoelectronic devices. Here, we systematically investigated the effect of the chiral structures of SWCNTs on their electrical transport properties by measuring the performance of thin-film transistors constructed by eleven distinct (n, m) single-chirality SWCNT films. The results show that, even for SWCNTs with the same diameters but different chiral angles, the difference in the on-state current or carrier mobility could reach an order of magnitude. Further analysis indicates that the electrical transport properties of SWCNTs have strong type and family dependence. With increasing chiral angle for the same-family SWCNTs, Type I SWCNTs exhibit increasing on-state current and mobility, while Type II SWCNTs show the reverse trend. The differences in the electrical properties of the same-family SWCNTs with different chiralities can be attributed to their different electronic band structures, which determine the contact barrier between electrodes and SWCNTs, intrinsic resistance and intertube contact resistance. Our present findings provide an important physical basis for performance optimization and application expansion of SWCNT-based devices.
- Published
- 2023
4. Ultrafast wafer-scale assembly of uniform and highly dense semiconducting carbon nanotube films for optoelectronics
- Author
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Xiaojun Wei, Jiaming Cui, Wei Su, Hiromichi Kataura, Sishen Xie, Futian Wang, Huaping Liu, Weiya Zhou, and Dehua Yang
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Electron mobility ,Materials science ,business.industry ,Photodetector ,02 engineering and technology ,General Chemistry ,Carbon nanotube ,Integrated circuit ,Photoelectric effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Responsivity ,law ,Optoelectronics ,General Materials Science ,Wafer ,0210 nano-technology ,business ,Ultrashort pulse - Abstract
We report an innovative method for the fast preparation of wafer-scale uniform single-wall carbon nanotubes (SWCNT) films with controllable density by NaHCO3 tuning the interaction between amine-functionalized substrates and surfactant-dispersing SWCNTs in aqueous solution. With this technique, a 4-inch SWCNT film with a linear density of ∼30 tubes/μm can be achieved in 1 s, and over 60 tubes/μm within 30 s using a high-concentration SWCNT solution. The SWCNT density changes by less than 8% over a 4-inch area. The electrical uniformity of the as-prepared wafer-scale single-chirality SWCNT film was demonstrated to be within 10.8% for subthreshold swing and 12% for carrier mobility and 13.5% for their on-current, which is the most uniform SWCNT films reported so far fabricated from the surfactant-dispersed SWCNT solution. Further, the photodetectors made by the uniform semiconducting SWCNT films exhibit excellent cascading ability, which linearly amplify the output photovoltages and could produce a photovoltage responsivity of 2.5 × 106 V/W. When three-stage cascading photodetectors are used as optical gate to establish an integrated photoelectric system, a 20-mW/cm2 light illumination produces the current responsivity of 147.3 A/W under a source/drain voltage of −0.1 V. Our present technique lays an important foundation for their applications in integrated circuits.
- Published
- 2020
5. Heterogeneous lead iodide obtains perovskite solar cells with efficiency of 24.27%
- Author
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Qianyu Liu, Zhu Ma, Yanlin Li, Guangyuan Yan, Dejun Huang, Shanyue Hou, Weiya Zhou, Xin Wang, Jie Ren, Yan Xiang, Rui Ding, Xuelin Yue, Zhuowei Du, Meng Zhang, Wenfeng Zhang, Lianfeng Duan, Yuelong Huang, and Yaohua Mai
- Subjects
General Chemical Engineering ,Environmental Chemistry ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2022
6. Negligible hysteresis planar perovskite solar cells using Ga-doped SnO2 nanocrystal as electron transport layers
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Zhuoyun Li, Jia Zhuang, Xiao Zheng, Hua Zhang, Changtao Peng, Zhu Ma, Weiya Zhou, and Yuelong Huang
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Materials science ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biomaterials ,Condensed Matter::Materials Science ,Planar ,Condensed Matter::Superconductivity ,Materials Chemistry ,Electrical and Electronic Engineering ,Gallium ,Perovskite (structure) ,business.industry ,Doping ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Tin oxide ,Ferroelectricity ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Hysteresis ,Nanocrystal ,chemistry ,Optoelectronics ,0210 nano-technology ,business - Abstract
Planar perovskite solar cells (PSCs) have been demonstrated as a promising architecture for efficient, large-scale, flexible and tandem solar cell. To date, unfortunately, most planar PSCs suffer from current-voltage hysteresis, which derives from interface mismatch, surface defects, ion migration, and ferroelectric property et al. Here, we demonstrate a facile strategy to significantly reduce the hysteresis and improve the performance of planar PSCs by doping gallium (Ga) into tin oxide (SnO2) nanocrystal electron-transport layer using low-temperature solution‐processed method. It is revealed that the Ga-doped SnO2 ETL owning better band alignment with the perovskite absorption layer, which is helpful for electron extraction. It is found that gallium doping severely decreases the trap state density in SnO2, leading to a lower recombination rate and negligible hysteresis. With the optimized doping concentration of Ga ions, the champion device achieves a highest PCE of 18.18% and the hysteresis index is reduced from 23.9% to 1.7%.
- Published
- 2019
7. Regulated perovskite crystallinity via green mixed antisolvent for efficient perovskite solar cells
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Jia Zhuang, Weiya Zhou, Hua Zhang, Zhu Ma, Xinyi Luo, Zhongli Guo, Shuangshuang Zhao, Haimin Li, and Jing Yi
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Supersaturation ,Materials science ,Nucleation ,Crystal growth ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Biomaterials ,Grain growth ,Crystallinity ,Chemical engineering ,law ,Materials Chemistry ,Crystallite ,Electrical and Electronic Engineering ,Crystallization ,0210 nano-technology ,Perovskite (structure) - Abstract
Organometallic halide perovskite absorption layer with excellent surface morphology and large grain size is very important for fabricating efficient perovskite solar cells (PSCs). The antisolvent assisted crystallization (ASAC) has been proved to be an effective tactic to prepare compact and uniform polycrystalline perovskite film. However, most of the antisolvents currently used are highly toxic, and the perovskite crystallization process is difficult to control using pure antisolvent. Here, a green strategy is developed to improve the nucleation kinetics of perovskite precursor and the perovskite crystallization process. A mixed green antisolvent of ethyl acetate (EA)/petroleum ether (PE) is employed to regulate the crystallization of perovskite and replace traditional chlorobenzene (CB) and pure EA. With optimized proportion of EA and PE, the supersaturation degree is controlled via reducing the solvent evaporation rate and the nucleation rate, and it is good for crystal growth. Moreover, the grain growth rate and grain size are easily regulated, which contribute to the uniform, large grain and non-pinhole perovskite film. Correspondingly, the intrinsic perovskite solar cells based on CH3NH3PbI3 achieve a power conversion efficiency of 17.19% and an average efficiency of 16.25% (std 0.43).
- Published
- 2019
8. Crystal recombination control by using Ce doped in mesoporous TiO2for efficient perovskite solar cells
- Author
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Jia Zhuang, Haimin Li, Haoran Xia, Zhu Ma, Xiao Zheng, Honglin Lu, Weiya Zhou, and Hua Zhang
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Electron mobility ,Materials science ,Fabrication ,business.industry ,General Chemical Engineering ,Doping ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electron transport chain ,0104 chemical sciences ,Crystal ,Nanocrystal ,Optoelectronics ,0210 nano-technology ,Mesoporous material ,business - Abstract
Efficient electron transport layers (ETLs) are the crucial issue for electron transport and hole blocking in organic–inorganic hybrid perovskite solar cells (PSCs). To date, most of the reported effective ETLs have comprised TiO2, which exhibits limited electron mobility and numerous defect states and restricts the enhancement of the performance of PSCs. Hence, the investigation of effective tactics for improving the electronic properties of TiO2 is critical for the fabrication of high-efficiency devices. In this study, a cerium doping method was adopted in mesoporous TiO2, which was prepared via a traditional one-step hydrothermal process, to improve its electron transport properties by recombining nanocrystals and optimizing the negative flat band potential of TiO2. Continuous, aligned and regulated recombined crystals of mesoporous TiO2 were obtained with optimized pathways of electron transport from the ETL to the FTO layer. Moreover, a small amount of Ti4+ ions was replaced by Ce4+ ions in the TiO2 lattice, which led to deformation of the TiO2 lattice and influenced the growth process of TiO2 grains. With an optimized mole proportion of Ce element in the TiO2 precursor, the power conversion efficiency (PCE) of perovskite solar cells was typically boosted to 17.75% in comparison with 15.92% in the case of undoped TiO2.
- Published
- 2019
9. Improving the performance of lead acetate-based perovskite solar cells via solvent vapor annealing
- Author
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Jing Yi, Honglin Lu, Yan Xiang, Haoran Xia, Haimin Li, Weiya Zhou, Zhongli Guo, Jia Zhuang, and Zhu Ma
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Materials science ,Annealing (metallurgy) ,Energy conversion efficiency ,Crystal growth ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Grain size ,0104 chemical sciences ,Grain growth ,Chemical engineering ,Lead acetate ,General Materials Science ,Grain boundary ,0210 nano-technology ,Perovskite (structure) - Abstract
Lead acetate-based perovskite solar cells (PSCs) have shown their superiority in terms of controlled grain growth and replacement of traditional lead halides, which is critical for their large-scale commercial applications; however, the lack of control on the grain quality of lead acetate-based perovskite still creates risks such as unwanted defects, pinholes and grain boundaries. Herein, we proposed a reliable method to control the morphology and grain size of lead acetate-based perovskites along with a dynamic solvent-vapor annealing treatment; it was found that the vapors of N,N-dimethylformamide (DMF) assisted in the growth of perovskite grains and facilitated the increase in grain size. Using optimized DMF volume, the fabricated planar PSCs with the structure FTO/TiO2/perovskite/spiro-OMeTAD/Ag achieved the highest power conversion efficiency (PCE) of 13.71%, which was 23.8% higher than that of the controlled device. Moreover, the hysteresis effect was negligible. The results demonstrate that the solvent vapor-assisted crystal growth process is a simple and facile way to improve the quality of lead acetate-based perovskites and increase their performance.
- Published
- 2019
10. Integrated, Highly Flexible, and Tailorable Thermoelectric Type Temperature Detectors Based on a Continuous Carbon Nanotube Fiber
- Author
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Jie Mei, Sishen Xie, Qiang Zhang, Weiya Zhou, Wenbin Zhou, Wei Xi, Xiaogang Xia, Yanchun Wang, and Zhuojian Xiao
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Materials science ,Physics::Instrumentation and Detectors ,business.industry ,Doping ,Detector ,General Chemistry ,Carbon nanotube ,law.invention ,Biomaterials ,Thermocouple ,law ,Thermoelectric effect ,Optoelectronics ,General Materials Science ,Node (circuits) ,Fiber ,Hybrid material ,business ,Biotechnology - Abstract
As possible alternatives to traditional thermoelectric (TE) materials, carbon nanomaterials and their hybrid materials have great potential in the future application of flexible and lightweight temperature detection. In this work, an integrated, highly flexible, and tailorable TE temperature detector with high performance has been fabricated based on a continuous single-walled carbon nanotube (SWCNT) fiber. The detector consists of more than one pairs of thermocouples composed of p-type SWCNT fiber and n-type SWCNT hybrid fiber in situ doped by polyethylenimine. Due to the node contact mechanism of the detection, the sensitivity of the detector can be improved with the increase of the number of p-n thermocouples, independent of the length of the thermocouple. The temperature detection process of the detector has been studied in detail. In particular, the integrated and flexible detector can be divided into several sub-detectors easily by cutting, illustrating the prospect of large-scale preparation of this kind of novel temperature detectors. Its high flexibility ensures the detector to maintain excellent detection performance after 15 000 bending circles. Furthermore, the as-designed TE type temperature detector demonstrates a great application promise for real-time temperature detection and temperature change sensing even in complex surface and harsh environment.
- Published
- 2021
11. All-Carbon Pressure Sensors with High Performance and Excellent Chemical Resistance
- Author
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Yanchun Wang, Xiaogang Gu, Nan Zhang, Xiaogang Xia, Zhuojian Xiao, Weiya Zhou, Qiang Zhang, and Sishen Xie
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Materials science ,Fabrication ,Oxide ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Nanomaterials ,law.invention ,Biomaterials ,chemistry.chemical_compound ,law ,General Materials Science ,business.industry ,Graphene ,Contact resistance ,Aerogel ,General Chemistry ,021001 nanoscience & nanotechnology ,Pressure sensor ,0104 chemical sciences ,chemistry ,Optoelectronics ,Chemical stability ,0210 nano-technology ,business ,Biotechnology - Abstract
An all-carbon pressure sensor is designed and fabricated based on reduced graphene oxide (rGO) nanomaterials. By sandwiching one layer of superelastic rGO aerogel between two freestanding high-conductive rGO thin papers, the sensor works based on the contact resistance at the aerogel-paper interfaces, getting rid of the alien materials such as polymers and metals adopted in traditional sensors. Without the limitation of alien materials, the all-carbon sensors demonstrate an ultrawide detecting range (0.72 Pa-130 kPa), low energy consumption (≈0.58 µW), ultrahigh sensitivity (349-253 kPa-1 ) at low-pressure regime (
- Published
- 2018
12. Interfacial modification using ultrasonic atomized graphene quantum dots for efficient perovskite solar cells
- Author
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Caichen Du, Zhu Ma, Jia Zhuang, Xiao Zheng, Weiya Zhou, Yuelong Huang, Xingchong Liu, Haoran Xia, Xiaowei Cheng, and Hua Zhang
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Materials science ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Biomaterials ,chemistry.chemical_compound ,Planar ,law ,Materials Chemistry ,Electrical and Electronic Engineering ,Aqueous solution ,business.industry ,Tin dioxide ,Graphene ,Energy conversion efficiency ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,Quantum dot ,Titanium dioxide ,Optoelectronics ,Ultrasonic sensor ,0210 nano-technology ,business - Abstract
Tin dioxide (SnO2) is a promising electron transport material to replace traditional titanium dioxide (TiO2) for fabricating efficient planar perovskite solar cells (PSCs). However, in order to realize process compatibility and larger scale device, low temperature solution processed SnO2 is normally used, which generates numerous trap states in ETL layer and directly affects the device performance. Here, an interfacial modification strategy proposed, depositing an ultrasonic atomized ultrathin graphene quantum dots (GQDs) layer between tin dioxide (SnO2) and perovskite layer. Ultrasonic atomized deposition can effectively prevent the damage of the surface chemical properties of SnO2 by aqueous solution. Additionally, we demonstrate that the GQDs change the surface property of SnO2 film, and optimized the charge transport capability in SnO2 and perovskite interface. Correspondingly, we obtained a significant power conversion efficiency (PCE) improvement for CH3NH3PbI3-based PSCs from 13.61% to 16.54% and reached a highest steady-state PCE over 16%. We believe that the interfacial modification engineering by means of ultrasonic atomizing process is a promising tactic to obtain efficient perovskite solar cells.
- Published
- 2019
13. High-performance and compact-designed flexible thermoelectric modules enabled by a reticulate carbon nanotube architecture
- Author
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Le Cai, Wenbin Zhou, Xiaogang Gu, Feng Yang, Kewei Li, Weiya Zhou, Qingxia Fan, Sishen Xie, Qiang Zhang, Huaping Liu, Nan Zhang, and Yanchun Wang
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Materials science ,Science ,General Physics and Astronomy ,Nanotechnology ,02 engineering and technology ,Carbon nanotube ,Power factor ,010402 general chemistry ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,law.invention ,law ,Thermoelectric effect ,Multidisciplinary ,High conductivity ,business.industry ,General Chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,0104 chemical sciences ,Thermoelectric generator ,Scalability ,Optoelectronics ,0210 nano-technology ,business - Abstract
It is a great challenge to substantially improve the practical performance of flexible thermoelectric modules due to the absence of air-stable n-type thermoelectric materials with high-power factor. Here an excellent flexible n-type thermoelectric film is developed, which can be conveniently and rapidly prepared based on the as-grown carbon nanotube continuous networks with high conductivity. The optimum n-type film exhibits ultrahigh power factor of ∼1,500 μW m−1 K−2 and outstanding stability in air without encapsulation. Inspired by the findings, we design and successfully fabricate the compact-configuration flexible TE modules, which own great advantages compared with the conventional π-type configuration modules and well integrate the superior thermoelectric properties of p-type and n-type carbon nanotube films resulting in a markedly high performance. Moreover, the research results are highly scalable and also open opportunities for the large-scale production of flexible thermoelectric modules., Thermoelectric modules can generate electricity directly from heat and have applications to waste heat-energy conversion. Here Zhou et al. have fabricated a thermoelectric module based on an air-stable n-type single-walled carbon nanotube sheet which can reach a high power factor of 1500 μWm−1K−2.
- Published
- 2017
14. Temperature Dependent Resistance of As-Grown and Chemical Treated Single Walled Carbon Nanotubes Films
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Haibo Dong, Qingsheng Zeng, Xiaoxian Zhang, Sishen Xie, Jinzhu Li, Le Cai, Duan Zhao, and Weiya Zhou
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Materials science ,Absorption spectroscopy ,Biomedical Engineering ,Bioengineering ,Nanotechnology ,General Chemistry ,Chemical vapor deposition ,Carbon nanotube ,Metallic conduction ,Condensed Matter Physics ,Catalysis ,law.invention ,symbols.namesake ,Chemical engineering ,law ,symbols ,General Materials Science ,Anisotropy ,Raman spectroscopy ,Quantum tunnelling - Abstract
Single Walled Carbon Nanotube (SWCNT) films were directly synthesized via Floating Catalyst Chemical Vapor Deposition (FCCVD) method. Temperature dependent resistance measurements were carried out on the as-grown and chemical treated SWCNTs films. A "U" shaped curve was obtained for each sample, with a significant variation in the crossover temperatures between the as-grown and treated samples. A heterogeneous model was adopted to interpret the experimental data, revealing the coexistence of anisotropic 1D metallic conduction, conventional metallic conduction and fluctuation assisted tunneling. Our results implied very low barriers, verifying the good intertube and interbundle contacts in the directly synthesized SWCNTs films. We speculated that oxidization and acid treatments would affect the overall configuration of the films, leading to the changes in the temperature dependence of resistance. In addition, Raman and absorption spectra indicated that oxidization and acid process would cause moderate changes in the hole carrier concentration of the films.
- Published
- 2013
15. In-Situ Raman Spectra of Single-Walled Carbon Nanotube/Epoxy Nanocomposite Film Under Strain
- Author
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Le Cai, Jinzhu Li, Sishen Xie, Zhiqiang Niu, Qingsheng Zeng, Duan Zhao, Xiaoxian Zhang, Haibo Dong, and Weiya Zhou
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Materials science ,Nanocomposite ,Strain (chemistry) ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Epoxy ,Carbon nanotube ,Condensed Matter Physics ,law.invention ,Stress (mechanics) ,symbols.namesake ,law ,visual_art ,symbols ,visual_art.visual_art_medium ,General Materials Science ,Composite material ,Deformation (engineering) ,Elasticity (economics) ,Raman spectroscopy - Abstract
In-situ Raman spectra under continuous strain have been carried out to follow the load transfer efficiency in a single-walled carbon nanotube/epoxy nanocomposite film, which was fabricated by a facile and filter-free infiltration method using directly synthesized SWNT film as skeleton. It was found that in the low elastic range of 1%, with the increase of applied strain, the G(-) and G(+) Raman bands downshift nearly lineally with corresponding ultrahigh rates up to -12 and -17 cm(-1)/% strain, respectively. As the applied strain decrease, these Raman bands upshift to their original frequencies with almost the same rates. These precise relationships between the Raman band shift and the applied strain enable this nanocomposite film promising stress or stain sensors. Furthermore, some Raman radial breathing modes (RBMs) disappear (appear) under larger strain (1.6%) and recover (vanish) when the strain is released, also verify the effective deformation of micro SWNTs induced by extra macro strain applied on the nanocomposite film. More interestingly, these frequency shifts and intensity vibrations are recoverable and repeatable, indicating the high elasticity of deformation in this strain region of 2%.
- Published
- 2013
16. Indium Tin Oxide Nanowires Grown by One-Step Thermal Evaporation-Deposition Process at Low Temperature
- Author
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Le Cai, Zhiqiang Niu, Sishen Xie, Haibo Dong, Xiaoxian Zhang, Jinzhu Li, Duan Zhao, and Weiya Zhou
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Materials science ,Silicon ,business.industry ,Biomedical Engineering ,Oxide ,Nanowire ,chemistry.chemical_element ,Bioengineering ,Nanotechnology ,General Chemistry ,Condensed Matter Physics ,law.invention ,Indium tin oxide ,chemistry.chemical_compound ,chemistry ,law ,Optoelectronics ,General Materials Science ,Atomic ratio ,Crystallization ,Vapor–liquid–solid method ,business ,High-resolution transmission electron microscopy - Abstract
Indium tin oxide (ITO), as one of the most important transparent conducting oxide, is widely used in electro-optical field. We have developed a simple one-step method to synthesize ITO nanowires at low temperature of 600 degrees C. In detail, mixtures of InN nanowires and SnO powder, with the molar ratio of 10:1, have been used as precursors for the thermal evaporation-deposition of ITO nanowires on silicon/quartz slices. During the growth process, the evaporation temperature is maintained at 600 degrees C, which favors the decomposition of InN and oxidation of In, with a limited incorporation of Sn in the resulting compound (In:Sn approximately 11:1 in atomic ratio). As far as we know, this is the lowest growth temperature reported on the thermal deposition of ITO nanowires. The diameters of the nanowires are about 120 nm and the lengths are up to tens of micrometers. XRD characterization indicates the high crystallization of the nanowires. HRTEM results show the nanowires grow along the [200] direction. The transmittance of the nanowire film on quartz slice is more than 75% in the visible region. Based on photolithography and lift-off techniques, four-terminal measurement was utilized to test the resistivity of individual nanowire (6.11 x 10(-4) omega x cm). The high crystallization quality, good transmittance and low resistivity make as-grown ITO nanowires a promising candidate as transparent electrodes of nanoscale devices.
- Published
- 2013
17. Optical and Electrical Performance of HfO2 Coated ZnO Nanorod Arrays
- Author
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Lihuan Zhang, Min Gao, Duan Zhao, Guoqing Yan, Le Cai, Sishen Xiel, Haibo Dong, Xiaoxian Zhang, Weiya Zhou, Qing Chen, Jun Shen, and Jinzhu Li
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Materials science ,Passivation ,Band gap ,business.industry ,Exciton ,Biomedical Engineering ,Bioengineering ,Nanotechnology ,General Chemistry ,engineering.material ,Condensed Matter Physics ,Surface coating ,Coating ,engineering ,Optoelectronics ,General Materials Science ,Nanorod ,business ,Luminescence ,Surface states - Abstract
In this paper, we demonstrate the optical and electrical performance of ZnO nanorod arrays after surface passivation. The material of larger band gaps (HfO2) was chosen for the surface passivation layer through atom layer deposition (ALD), in order to confine the carriers within the core material efficiently. In the case of nanorods with high defects, HfO2 coating treatment not only improved near band edge (NBE) but also greatly enhanced the defect luminescence, while in the case of nanorods with low defects, surface coating suppressed defect luminescence and promoted the NBE emission as well as electrical performance therein. PL investigation at 10 K displayed that after surface coating phonon related emission was confined along c-axis and the exciton emission related to surface states was largely restrained. Therefore, it's suggested that surface passivation of ZnO nanorod arrays decreases the surface defect, enhances the side confinement of nanorod, and thus improves the optical and electrical performance efficiently.
- Published
- 2013
18. A Facile Method to Fabricate Ultrathin Vertical ZnO Nanowall Arrays
- Author
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Weiya Zhou, Duan Zhao, Haibo Dong, Chaoying Wang, Qingsheng Zeng, Xiaoxian Zhang, Le Cai, Sishen Xie, and Jinzhu Li
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Materials science ,Fabrication ,Biomedical Engineering ,Nanoparticle ,Polishing ,Bioengineering ,Nanotechnology ,General Chemistry ,Chemical vapor deposition ,Condensed Matter Physics ,Catalysis ,Atom ,medicine ,General Materials Science ,Tube furnace ,Activated carbon ,medicine.drug - Abstract
We demonstrate a facile method to synthesize ultrathin vertical ZnO nanowall arrays only through a one-step catalyst fabrication procedure. After being coated with uniformly dispersed gold particles, the substrates were polished gently to create discrete gold nanoparticle alignment as catalyst. The commercial ZnO powder and activated carbon powder with an atom ratio of 1:1 were utilized as source materials, and the whole growth process occurred in a conventional tube furnace chemical vapor deposition (CVD) system. The SEM images confirm that the ZnO nanowall arrays grow vertically along certain tracks made by polishing. The walls are about 17 nm wide, 90 nm high and 1 microm long after 90 min growth. After second growth, the nanowalls become 20 nm wide, 205 nm high, and 2 microm long. AFM images indicate that the alignment of discrete Au particles with certain separations due to polishing plays the key role in realizing vertical ZnO nanowall arrays.
- Published
- 2013
19. A Repeated Halving Approach to Fabricate Ultrathin Single‐Walled Carbon Nanotube Films for Transparent Supercapacitors
- Author
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Zhiqiang Niu, Haibo Dong, Jun Chen, Sishen Xie, Jinzhu Li, Wenjun Ma, Weiya Zhou, Guoxing Feng, Hong Li, and Yong-Sheng Hu
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Supercapacitor ,Nanotube ,Materials science ,Nanotubes, Carbon ,Surface Properties ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Chinese academy of sciences ,law.invention ,Biomaterials ,law ,Basic research ,General Materials Science ,Biotechnology - Abstract
Ultrathin SWCNT transparent and conductive films on flexible and transparent substrates are prepared via repeatedly halving the directly grown SWCNT films and flexible and transparent supercapacitors with excellent performance were fabricated.
- Published
- 2012
20. Ultrahigh-Power-Factor Carbon Nanotubes and an Ingenious Strategy for Thermoelectric Performance Evaluation
- Author
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Yanchun Wang, Shiqi Xiao, Qiang Zhang, Wenbin Zhou, Sishen Xie, Huiliang Chen, Huaping Liu, Xiaogang Gu, Kewei Li, Feng Yang, Le Cai, Zhuojian Xiao, Weiya Zhou, Qingxia Fan, and Nan Zhang
- Subjects
Materials science ,Nanotechnology ,02 engineering and technology ,Carbon nanotube ,010402 general chemistry ,01 natural sciences ,law.invention ,Biomaterials ,Thermal conductivity ,Potential applications of carbon nanotubes ,law ,Seebeck coefficient ,Thermoelectric effect ,General Materials Science ,Thin film ,Nanotubes, Carbon ,Electric Conductivity ,Temperature ,General Chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,0104 chemical sciences ,Optical properties of carbon nanotubes ,0210 nano-technology ,Biotechnology - Abstract
An ingenious strategy is put forward to evaluate accurately the thermoelectric performance of carbon nanotube (CNT) thin films, including thermal conductivity, electrical conductivity, and Seebeck coefficient in the same direction. The results reveal that the as-prepared CNT interconnected films and CNT fibers possess enormous potential of thermoelectric applications because of their ultrahigh power factors.
- Published
- 2016
21. Design of AgM Bimetallic Alloy Nanostructures (M = Au, Pd, Pt) with Tunable Morphology and Peroxidase-Like Activity
- Author
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Sishen Xie, Shuai Hou, Xiaona Hu, Weiwei He, Xiaochun Wu, Jianbo Liu, Weiya Zhou, and Ke Zhang
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Nanostructure ,Materials science ,General Chemical Engineering ,Alloy ,Nanoparticle ,Nanotechnology ,General Chemistry ,engineering.material ,Platinum nanoparticles ,Silver nanoparticle ,Colloidal gold ,Transmission electron microscopy ,Materials Chemistry ,engineering ,Bimetallic strip - Abstract
Bimetallic alloy nanoparticles (NPs) exhibit unique optical and catalytic properties that are dependent on their morphology and composition. In this paper, a general and facile way was developed to prepare Ag-related bimetallic alloy NPs with hollow/porous structures, including AgAu, AgPd, and AgPt. The formation of the alloy structures is evidenced by high-resolution transmission electron microscopy (TEM), scanning transmission electron microscopy−energy-dispersive X-ray analysis (STEM-EDX) mapping, and ultraviolet−visible−near-infrared (UV−vis−NIR) absorption spectra. AgM alloy NPs exhibit peroxidase-like activity. A unique composition dependence is found and can be used to tailor the catalytic activity. In addition to the recent discoveries about peroxidase mimetics on Fe3O4 NPs and sheetlike FeS nanostructures, our findings suggest a new type of candidate as peroxidase mimics. Furthermore, for noble metals, apart from size and shape, tailoring the composition poses another effective way to tune the ca...
- Published
- 2010
22. High-Strength Composite Fibers: Realizing True Potential of Carbon Nanotubes in Polymer Matrix through Continuous Reticulate Architecture and Molecular Level Couplings
- Author
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Zhiqiang Niu, Pulickel M. Ajayan, Wenjun Ma, Xiao-su Yi, Rong Yang, Haibo Dong, Gang Liu, Zhong Zhang, Sishen Xie, Jinzhu Li, Xuefeng An, Taihua Zhang, Weiya Zhou, Yan Ren, and Luqi Liu
- Subjects
chemistry.chemical_classification ,Nanotube ,Nanocomposite ,Nanostructure ,Materials science ,Mechanical Engineering ,Composite number ,Thermosetting polymer ,Bioengineering ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Polymer ,Condensed Matter Physics ,law.invention ,chemistry ,law ,General Materials Science ,Composite material ,Nanoscopic scale - Abstract
Carbon nanotubes have unprecedented mechanical properties as defect-free nanoscale building blocks, but their potential has not been fully realized in composite materials due to weakness at the interfaces. Here we demonstrate that through load-transfer-favored three-dimensional architecture and molecular level couplings with polymer chains, true potential of CNTs can be realized in composites as initially envisioned. Composite fibers with reticulate nanotube architectures show order of magnitude improvement in strength compared to randomly dispersed short CNT reinforced composites reported before. The molecular level couplings between nanotubes and polymer chains results in drastic differences in the properties of thermoset and thermoplastic composite fibers, which indicate that conventional macroscopic composite theory fails to explain the overall hybrid behavior at nanoscale.
- Published
- 2009
23. Synthesis of large-scale periodic ZnO nanorod arrays and its blue-shift of UV luminescence
- Author
-
Min Gao, Lihuan Zhang, Sishen Xie, Wenliang Li, Dongfang Liu, Weiya Zhou, Zhiqiang Niu, Qingsheng Zeng, Xiaoxian Zhang, Wenjun Ma, and Yan Ren
- Subjects
Materials science ,Photoluminescence ,business.industry ,Nanowire ,Nanoparticle ,Nanotechnology ,General Chemistry ,Substrate (electronics) ,medicine.disease_cause ,Materials Chemistry ,medicine ,Optoelectronics ,Nanorod ,business ,Luminescence ,Dispersion (chemistry) ,Ultraviolet - Abstract
We demonstrate a promising route to fabricate large scale hexagonally patterned, vertically aligned ZnO nanorod arrays with small diameter. By adding 3-mercaptopropyltriethoxysilane (MPTES) molecules as a connection between catalyst and substrate the large size dispersion resulting from the removal of catalyst pattern is avoided, thus the catalyst particle pattern with tiny size dispersion and regular shape is obtained; the size can be tuned in a large range from 50 nm to 300 nm. Using this technique, ZnO nanorod arrays with tunable spacings and diameters are achieved, which also have uniform shape and length, good crystal quality, and vertical alignment on the substrate. Moreover, a pronounced blue-shift of ultraviolet (UV) luminescence spectra of ZnO nanorods with their diameters decreasing is observed. Combining the temperature-dependent photoluminescence (PL), we suggest that a materially decreased exciton-phonon interaction with the reduced diameter of ZnO nanorods is the main reason for the blue-shift of UV luminescence.
- Published
- 2009
24. ZnO Tetrapods Designed as Multiterminal Sensors to Distinguish False Responses and Increase Sensitivity
- Author
-
Zengxing Zhang, Changzhi Gu, Weiya Zhou, Yuanchun Zhao, Dongfang Liu, Binsuo Zou, Sishen Xie, Li Cao, Lianfeng Sun, and Zheng Liu
- Subjects
Optics and Photonics ,Materials science ,Light ,Transducers ,Bioengineering ,Sensitivity and Specificity ,Signal ,Particle detector ,Ultraviolet light ,Nanotechnology ,General Materials Science ,Sensitivity (control systems) ,Lithography ,business.industry ,Mechanical Engineering ,Reproducibility of Results ,Equipment Design ,General Chemistry ,Condensed Matter Physics ,Nanostructures ,Equipment Failure Analysis ,Wavelength ,Transducer ,Nanoelectronics ,Optoelectronics ,Zinc Oxide ,business ,Microelectrodes - Abstract
Individual zinc oxide tetrapods were designed as multiterminal sensors by the e-beam lithography method. Different from double-terminal sensors, these sensors can give multiple responses to a single signal at the same time. The designed tetrapod devices were employed to detect light with different wavelength. The results indicate that they are remarkable optoelectronic devices, sensitive to ultraviolet light, and have advantages on distinguishing noises and increasing sensitivity. This should be helpful for weak signal measurements of nanodevices.
- Published
- 2008
25. Single-Crystal and Twinned Zn2SnO4 Nanowires with Axial Periodical Structures
- Author
-
Weiya Zhou, Xiao Wei Sun, Yi Yang, Jianxiong Wang, and Shishen Xie
- Subjects
Nanostructure ,Photoluminescence ,Materials science ,Nanowire ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Zinc ,Condensed Matter Physics ,Evaporation (deposition) ,Crystallographic defect ,Chemical engineering ,chemistry ,Macle ,General Materials Science ,Single crystal - Abstract
Single-crystal Zn2SnO4 (ZTO) nanowires were synthesized by thermal evaporation of a mixture of Zn and SnO powders at 1000 °C. The ZTO nanowires showed unique periodical structures in contrast to the traditional nanowires. It was found that the yield of the single-crystal ZTO nanowires was strongly dependent on the weight ratio of Zn and SnO in the source mixture. With the decrease of Zn content in the source, twinned ZTO nanowires with alternating (111) twins along the axial direction can be obtained. The formation mechanism of these ZTO nanostructures is discussed. The photoluminescence of the ZTO nanowires was measured.
- Published
- 2007
26. Effect of H2O adsorption on the electrical transport properties of double-walled carbon nanotubes
- Author
-
Dongsheng Tang, Lijie Ci, Sishen Xie, and Weiya Zhou
- Subjects
Electron density ,Chemistry ,Doping ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Electron ,law.invention ,Condensed Matter::Materials Science ,Dipole ,Electric dipole moment ,Adsorption ,law ,Chemical physics ,Molecule ,General Materials Science ,Physics::Chemical Physics - Abstract
Water molecules adsorbed on a double-walled carbon nanotube (DWCNT) serve as charge trapping centers when present in low density and as electron donors when present in high density. There is a discontinuous change between the low- and high-density regions. H2O molecules are apt to be adsorbed on the outer surface of DWCNTs, and in this case the electrical transport properties are extremely sensitive to environment, which suggests that DWCNTs are hole doped and act as an electric dipole with the inner tube.
- Published
- 2006
27. The growth of carbon nanostructures in the channels of aligned carbon nanotubes
- Author
-
Gang Wang, Shudong Luo, Sishen Xie, Zengxing Zhang, Weiya Zhou, Shicheng Mu, Peng Jiang, Lifeng Liu, Weiguo Chu, Dongfang Liu, Yanjuan Xiang, Li Song, and Xiaowei Zhao
- Subjects
Carbon nanostructures ,Nanostructure ,Materials science ,Carbon nanofiber ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Chemical vapor deposition ,Microstructure ,law.invention ,Carbon nanobud ,chemistry ,law ,General Materials Science ,Carbon - Published
- 2006
28. Efficiently producing single-walled carbon nanotube rings and investigation of their field emission properties
- Author
-
Lifeng Liu, Zengxing Zhang, Sishen Xie, Jun Shen, Xiaowei Zhao, Li Song, Jianjun Zhou, Wenjun Ma, Weiya Zhou, Dongfang Liu, Lianfeng Sun, Shudong Luo, Yanjuan Xiang, Lijie Ci, Ping-Heng Tan, and Chuanhong Jin
- Subjects
Materials science ,Physics::Medical Physics ,Bioengineering ,Carbon nanotube ,Catalysis ,law.invention ,Condensed Matter::Materials Science ,law ,General Materials Science ,Electrical and Electronic Engineering ,Composite material ,High-resolution transmission electron microscopy ,Electronic properties ,chemistry.chemical_classification ,Toroid ,Mathematics::Commutative Algebra ,Condensed Matter::Other ,Mechanical Engineering ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Field electron emission ,Hydrocarbon ,Chemical engineering ,chemistry ,Mechanics of Materials ,Sublimation (phase transition) - Abstract
Single-walled carbon nanotube (SWNT) rings with a diameter of about 100 nm have been prepared by thermally decomposing hydrocarbon in a floating catalyst system. These rings appeared to consist mostly of SWNT toroids. High resolution transmission electron microscopy showed that these rings were composed of tens of SWNTs with a tightly packed arrangement. The production of SWNT rings was improved through optimizing various growth parameters, such as growth temperature, sublimation temperature of the catalyst, different gas flows and different catalyst components. The growth mechanism of the SWNT rings is discussed. In the field emission measurements we found that field emission from a halved ring is better than that from a whole SWNT ring, which contributed to the better emission from two opened ends of the nanotubes of the halved SWNT ring.
- Published
- 2006
29. Postgrowth alignment of SWNTs by an electric field
- Author
-
Dongyun Wan, Xinyuan Dou, Li Song, Zhenping Zhou, Weiya Zhou, and Sishen Xie
- Subjects
Carbon nanotube quantum dot ,Optical properties of carbon nanotubes ,Materials science ,Potential applications of carbon nanotubes ,Carbon nanofiber ,law ,Electric field ,General Materials Science ,Nanotechnology ,General Chemistry ,Chemical vapor deposition ,Carbon nanotube ,law.invention - Published
- 2006
30. Patterned anodic aluminium oxide fabricated with a Ta mask
- Author
-
Jiafeng Feng, Zengxing Zhang, Jianxiong Wang, Dongfang Liu, Lifeng Liu, Li Song, Peng Jiang, Xiaowei Zhao, Sishen Xie, Shudong Luo, Gang Wang, Yanjuan Xiang, Xinyuan Dou, Yan Gao, and Weiya Zhou
- Subjects
Materials science ,Anodizing ,Scanning electron microscope ,Mechanical Engineering ,Metallurgy ,Tantalum ,chemistry.chemical_element ,Bioengineering ,General Chemistry ,Substrate (electronics) ,Microstructure ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Aluminium ,Aluminium oxide ,General Materials Science ,Wetting ,Electrical and Electronic Engineering ,Composite material - Abstract
Electrochemical anodization was applied to an aluminium (Al) sheet patterned with a metallic tantalum (Ta) mask, which gave rise to the formation of patterned anodic aluminium oxide (AAO). The morphological evolution of the AAO porous structure with anodizing time was characterized by scanning electron microscopy. Lateral anodizing of the Al sheet gradually developed underneath the metallic Ta mask with the increase of anodizing time. This has given us further understanding of the Al anodizing behaviour compared with our previous work with a SiO2 masked Al sheet. By controlling the anodizing time and the size of the metal mask, deep lithography of the Al substrate can be realized, and a mushroom-like Ta–Al microstructure with a high aspect ratio was created on the Al surface after removal of the AAO film. This Ta–Al microstructure has been studied in detail, and it was found to exhibit pronounced hydrophobic properties.
- Published
- 2005
31. Electrochemical fabrication and structure of NixZn1−xalloy nanowires
- Author
-
Sishen Xie, Lifeng Liu, Gang Wang, Yanjuan Xiang, Jianxiong Wang, Yan Gao, Weiya Zhou, Xiaowei Zhao, Shudong Luo, Xinyuan Dou, Dongfang Liu, Li Song, Zengxing Zhang, and Caoying Wang
- Subjects
Diffraction ,Materials science ,Reflection high-energy electron diffraction ,Scanning electron microscope ,Mechanical Engineering ,Nanowire ,Bioengineering ,Nanotechnology ,General Chemistry ,Microstructure ,Electron diffraction ,Mechanics of Materials ,Transmission electron microscopy ,General Materials Science ,Electrical and Electronic Engineering ,Electron backscatter diffraction - Abstract
NixZn1?x alloy nanowires were successfully prepared by the templated electrodeposition technique. The morphology and the microstructures of as-deposited nanowires were examined by scanning electron microscope, x-ray diffraction, transmission electron microscope and electron diffraction. It is demonstrated that the content of magnetic element Ni in the nanowires can be easily adjusted by changing the ingredients of the electrolyte, the deposited current density and the deposited voltage, which is critical to tune the magnetic property of the nanowires. X-ray diffraction and electron diffraction analysis indicate that the NixZn1?x nanowires exhibit different structures with the variation in the quantity of nickel in the nanowires. It is expected that these heterogeneous alloy nanowires will have a potential application in nanoscale giant-magnetoresistance devices.
- Published
- 2005
32. Two possible emission mechanisms involved in the arc discharge method of carbon nanotube preparation
- Author
-
Dongsheng Tang, Jianjun Zhou, Sishen Xie, Lianfeng Sun, and Weiya Zhou
- Subjects
Materials science ,Shell (structure) ,Nanotechnology ,Thermionic emission ,General Chemistry ,Carbon nanotube ,Electron ,Cathode ,law.invention ,Electric arc ,Field electron emission ,law ,Chemical physics ,General Materials Science ,Graphite - Abstract
By investigating the morphologies and microstructures of the cathode deposits prepared by self-sustained arc discharge between graphite rods, we consider that there are two electron emission mechanisms occurring on the cathode: field emission and thermionic emission. The former occurs mainly on the edge of the growing surface, by which we can explain the formation of the outer hard shell of the cathode deposit; while the latter occurs mainly on the growing surface except for the edge area and it is the main cause for the growth of carbon nanotubes.
- Published
- 2005
33. Multidimensional magnesium oxide nanostructures with cone-shaped branching
- Author
-
Zhenping Zhou, Jianqi Li, Dongfang Liu, Xiaoqin Yan, Yan Gao, Li Song, Sishen Xie, Dongyun Wan, H. Chen, Weiya Zhou, Jianxiong Wang, Lifeng Liu, Huajun Yuan, and Yutian Wang
- Subjects
Fabrication ,Nanostructure ,Magnesium ,Nanoscale Science ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Chemical vapor deposition ,Condensed Matter Physics ,Branching (polymer chemistry) ,chemistry ,Materials Chemistry ,Nanometre ,Nanoscopic scale - Abstract
Branching structures in nanometer level are of great importance in developing nanoscale science and functional electrical devices. In this letter, multidimensional magnesium oxide structures with cone-shaped branching have been mass-produced using a simple chemical vapor deposition method. The dominant structures in the product include two-dimensional ‘+’, ‘T’, or ‘Γ’ assemblies, and three-dimensional complex configurations. The results presented here enrich the nanoscale community with new basic materials for the fabrication of functional electrical and chemical sensing devices.
- Published
- 2004
34. Controllable growth of double wall carbon nanotubes in a floating catalytic system
- Author
-
Gang Wang, Huajun Yuan, Weiya Zhou, Zhenping Zhou, Xiaoqin Yan, Xihua Chen, Sishen Xie, Dongfang Liu, Lijie Ci, Yingxin Liang, and Dongsheng Tang
- Subjects
chemistry.chemical_classification ,Analytical chemistry ,chemistry.chemical_element ,General Chemistry ,Carbon nanotube ,Partial pressure ,law.invention ,Catalysis ,chemistry.chemical_compound ,Hydrocarbon ,Acetylene ,chemistry ,Ferrocene ,Chemical engineering ,law ,Cobaltocene ,General Materials Science ,Carbon - Abstract
Double-wall carbon nanotubes (DWCNTs) have been better prepared by thermally decomposing ferrocene mixed with sulphur in the mixture flows of argon and acetylene at 950–1150 °C. The product of DWCNTs has been systematically studied as a function of the reaction temperature, the partial pressure of hydrocarbon, the sublimed temperature of ferrocene, and the relative molar value of ferrocene to sulphur. Our efforts to optimize the catalyst composition by replacing the partial ferrocene with cobaltocene have been proved to be inappropriate. In this process, the role of sulphur on the preparation condition has also been discussed.
- Published
- 2003
35. Preparation and characterization of junction-like multiwall carbon nanotubes
- Author
-
Yoshio Bando, Sishen Xie, Yubao Li, and Weiya Zhou
- Subjects
Electric arc ,chemistry ,Scanning electron microscope ,Transmission electron microscopy ,law ,chemistry.chemical_element ,General Materials Science ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Carbon ,law.invention ,Characterization (materials science) - Published
- 2003
36. Producing cleaner double-walled carbon nanotubes in a floating catalyst system
- Author
-
Lifeng Liu, Sishen Xie, Huajun Yuan, Dongfang Liu, Jianxiong Wang, Li Song, Gang Wang, Lijie Ci, Zhenping Zhou, Weiya Zhou, Yan Gao, and Xiaoqin Yan
- Subjects
Nanotube ,Double walled ,Materials science ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Chemical vapor deposition ,law.invention ,Catalysis ,symbols.namesake ,chemistry ,Chemical engineering ,law ,Impurity ,symbols ,General Materials Science ,Carbon ,Raman scattering - Abstract
We demonstrate that Fe impurities in double-walled carbon nantoubes (DWNTs) may be greatly depressed by improving the experimental setup in a floating catalyst CVD method. In the paper, the effect of different experimental parameters on sample purity has been systematically studied. The possible reasons for the decrease of impurity in the DWNT samples prepared with the improved apparatus are discussed. The process should be helpful for preparing high quality single- or double-walled carbon nanotubes in scale-up applications.
- Published
- 2003
37. Effect of cupped cathode on microstructures of carbon nanotubes in arc discharge
- Author
-
Dongsheng Tang, Dongfang Liu, Yingxin Liang, Sishen Xie, Wei Liu, Weiya Zhou, Lijie Ci, Zhenping Zhou, Huajun Yuan, Z. Q. Liu, and Xiaoqin Yan
- Subjects
Chemistry ,Scanning electron microscope ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Carbon nanotube ,Growth model ,Microstructure ,Cathode ,law.invention ,Electric arc ,law ,Transmission electron microscopy ,General Materials Science ,Composite material ,Carbon - Published
- 2002
38. Designing hybrid gate dielectric for fully printing high-performance carbon nanotube thin film transistors
- Author
-
Huaping Liu, Qian Li, Sishen Xie, Wei Su, Yanchun Wang, Dehua Yang, Shilong Li, and Weiya Zhou
- Subjects
Electron mobility ,Materials science ,business.industry ,Mechanical Engineering ,Gate dielectric ,Bioengineering ,02 engineering and technology ,General Chemistry ,Dielectric ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Threshold voltage ,Mechanics of Materials ,Thin-film transistor ,Optoelectronics ,General Materials Science ,Charge carrier ,Electrical and Electronic Engineering ,Electric current ,0210 nano-technology ,business ,Leakage (electronics) - Abstract
The electrical characteristics of carbon nanotube (CNT) thin-film transistors (TFTs) strongly depend on the properties of the gate dielectric that is in direct contact with the semiconducting CNT channel materials. Here, we systematically investigated the dielectric effects on the electrical characteristics of fully printed semiconducting CNT-TFTs by introducing the organic dielectrics of poly(methyl methacrylate) (PMMA) and octadecyltrichlorosilane (OTS) to modify SiO2 dielectric. The results showed that the organic-modified SiO2 dielectric formed a favorable interface for the efficient charge transport in s-SWCNT-TFTs. Compared to single-layer SiO2 dielectric, the use of organic-inorganic hybrid bilayer dielectrics dramatically improved the performances of SWCNT-TFTs such as mobility, threshold voltage, hysteresis and on/off ratio due to the suppress of charge scattering, gate leakage current and charge trapping. The transport mechanism is related that the dielectric with few charge trapping provided efficient percolation pathways for charge carriers, while reduced the charge scattering. High density of charge traps which could directly act as physical transport barriers and significantly restrict the charge carrier transport and, thus, result in decreased mobile carriers and low device performance. Moreover, the gate leakage phenomenon is caused by conduction through charge traps. So, as a component of TFTs, the gate dielectric is of crucial importance to the manufacture of high quality TFTs from the aspects of affecting the gate leakage current and device operation voltage, as well as the charge carrier transport. Interestingly, the OTS-modified SiO2 allows to directly print horizontally aligned CNT film, and the corresponding devices exhibited a higher mobility than that of the devices with the hybrid PMMA/SiO2 dielectric although the thickness of OTS layer is only ∼2.5 nm. Our present result may provide key guidance for the further development of printed nanomaterial electronics.
- Published
- 2017
39. Photothermal deflection spectra of crystalline C 60 S x and RbC 60
- Author
-
Sishen Xie, Lianfeng Sun, Luxi Qian, Gang Wang, Shengfa Qian, Dongsheng Tang, Z. Q. Liu, and Weiya Zhou
- Subjects
Crystal ,Materials science ,Absorption edge ,Analytical chemistry ,Molecule ,General Materials Science ,General Chemistry ,Metal–insulator transition ,Condensed Matter Physics ,Spectroscopy ,Single crystal ,Spectral line ,Blueshift - Abstract
The optical absorption spectra of C-60, C60Sx single crystals and polymerized crystalline RbC60 in the weak-absorption region (from 0.6 to 2.3 eV) have been measured by photothermal deflection spectroscopy (PDS). The optical energy gaps, E-opt, corresponding to optically forbidden transitions of weak absorption, were derived from Tauc plots as 1.63 and 1.72 eV for the single crystal C-60 and C60Sx, respectively. The weak-absorption characteristics of crystalline C-60, C60Sx and RbC60 are discussed. With respect to pristine C-60, the absorption edge of the single crystal of C60Sx shows a blue shift of about 0.1 eV, indicating that C-60 is electronically isolated in this compound. The absorption edge of polymerized RbC60 crystal, however, red-shift significantly in PDS, implying that there is electronic interaction between the host C-60 molecules and the guest Rb atoms. (C) 2000 Elsevier Science Ltd. All rights reserved.
- Published
- 2000
40. Growth of single crystal zinc oxide beaded nanowires
- Author
-
Zengxing Zhang, Sishen Xie, Yunxian Guo, Lianfeng Sun, and Weiya Zhou
- Subjects
Photoluminescence ,Materials science ,Band gap ,business.industry ,Biomedical Engineering ,Nanowire ,Bioengineering ,Nanotechnology ,General Chemistry ,Condensed Matter Physics ,Semiconductor ,General Materials Science ,Nanorod ,business ,Single crystal ,Quantum well ,Wurtzite crystal structure - Abstract
Reported here is the growth of single crystal zinc oxide beaded nanowires. The beaded nanowires are composed of nanobeads and ultrafine joint nanorods, which alternatively epitaxially grow along [001] direction of zinc oxide wurtzite structure. The growth mechanism was discussed and a zinc-rich process was proposed. Due to the size confinement, the bandgap along the beaded nanowires is modulated by their diameter and like multiple quantum well structure. Different from traditional multiple quantum well structures through alternate heterogeneous epitaxial growth of semiconductors, this kind of quasi-one-dimensional homogeneous multiple quantum well structures is composed of same substance. Their bandgap is modulated through alternately adjusting their diameter along single crystal nanowires. Further studies exhibit that they are of special properties on photoluminescence and Raman spectra. The demonstration would open the route to synthesize homogeneous multiple quantum well structures, study their fundamental physical phenomena, and exploit their applications.
- Published
- 2013
41. Double Wall Carbon Nanotubes with an Inner Diameter of 0.4 nm
- Author
-
Dongsheng Tang, Sishen Xie, Lijie Ci, Gang Wang, Yingxin Liang, Dongfang Liu, Weiya Zhou, Xiaoqin Yan, Huajun Yuan, and Zhenping Zhou
- Subjects
Nanotube ,Materials science ,Carbon nanofiber ,Process Chemistry and Technology ,chemistry.chemical_element ,Nanotechnology ,Surfaces and Interfaces ,General Chemistry ,Carbon nanotube ,Partial pressure ,law.invention ,symbols.namesake ,Chemical engineering ,chemistry ,law ,symbols ,High-resolution transmission electron microscopy ,Raman spectroscopy ,Carbon ,Raman scattering - Abstract
Communication: Selective preparation of double wall carbon nanotubes(DWCNTs) is achieved by a floating iron catalyst CVD method with sufur promotion. SEM shows that the product consists of entangled nanotubes. HRTEM and Raman scattering have revealed that the smallest inner diameter of as-grown carbon nanotubes is 0.4 nm (see Figure). The smallest diameter is found to be produced at the low carbon partial pressure with low sulfur content.
- Published
- 2003
42. Electrophoretic build-up of alternately multilayered films and micropatterns based on graphene sheets and nanoparticles and their applications in flexible supercapacitors
- Author
-
Sishen Xie, Yinghui Sun, Xuebo Cao, Huey Hoon Hng, Jan Ma, Xiaodong Chen, Jianjun Du, Zhiqiang Niu, Weiya Zhou, and School of Materials Science & Engineering
- Subjects
Electrophoresis ,Supercapacitor ,Fabrication ,Materials science ,Graphene ,Oxide ,Nanoparticle ,Nanotechnology ,Graphite oxide ,General Chemistry ,law.invention ,Biomaterials ,chemistry.chemical_compound ,chemistry ,law ,Electrode ,Nanoparticles ,Graphite ,General Materials Science ,Electronics ,Nanoscopic scale ,Biotechnology - Abstract
Graphene nanosheets and metal nanoparticles (NPs) have been used as nano-building-blocks for assembly into macroscale hybrid structures with promising performance in electrical devices. However, in most graphene and metal NP hybrid structures, the graphene sheets and metal NPs (e.g., AuNPs) do not enable control of the reaction process, orientation of building blocks, and organization at the nanoscale. Here, an electrophoretic layer-by-layer assembly for constructing multilayered reduced graphene oxide (RGO)/AuNP films and lateral micropatterns is presented. This assembly method allows easy control of the nano-architecture of building blocks along the normal direction of the film, including the number and thickness of RGO and AuNP layers, in addition to control of the lateral orientation of the resultant multilayered structures. Conductivity of multilayered RGO/AuNP hybrid nano-architecture shows great improvement caused by a bridging effect of the AuNPs along the out-of-plane direction between the upper and lower RGO layers. The results clearly show the potential of electrophoretic build-up in the fabrication of graphene-based alternately multilayered films and patterns. Finally, flexible supercapacitors based on multilayered RGO/AuNP hybrid films are fabricated, and excellent performance, such as high energy and power densities, are achieved.
- Published
- 2012
43. Superfast-response and ultrahigh-power-density electromechanical actuators based on hierarchal carbon nanotube electrodes and chitosan
- Author
-
Sishen Xie, Duan Zhao, Le Cai, Weiya Zhou, Li Song, Zhiqiang Niu, Wenjun Ma, Haibo Dong, Qingsheng Zeng, Xiaoxian Zhang, and Jinzhu Li
- Subjects
Materials science ,Fabrication ,Transducers ,Bimorph ,Bioengineering ,Carbon nanotube ,law.invention ,Electric Power Supplies ,law ,Electroactive polymers ,Nanotechnology ,General Materials Science ,Composite material ,Power density ,Supercapacitor ,Chitosan ,business.industry ,Nanotubes, Carbon ,Mechanical Engineering ,General Chemistry ,Equipment Design ,Micro-Electrical-Mechanical Systems ,Condensed Matter Physics ,Equipment Failure Analysis ,Electrode ,Optoelectronics ,Artificial muscle ,business ,Microelectrodes - Abstract
Here we report a novel single-walled carbon nanotube (SWNT) based bimorph electromechanical actuator, which consists of unique as-grown SWNT films as double electrode layers separated by a chitosan electrolyte layer consisting of an ionic liquid. By taking advantage of the special hierarchical structure and the outstanding electrical and mechanical properties of the SWNT film electrodes, our actuators show orders-of-magnitude improvements in many aspects compared to previous ionic electroactive polymer (i-EAP) actuators, including superfast response (19 ms), quite wide available frequency range (dozens to hundreds of Hz), incredible large stress generating rate (1080 MPa/s), and ultrahigh mechanical output power density (244 W/kg). These remarkable achievements together with their facile fabrication, low driving voltage, flexibility, and long durability enable the SWNT-based actuators many applications such as artificial muscles for biomimetic flying insects or robots and flexible deployable reflectors.
- Published
- 2011
44. Enhanced ionic conductivity of AgI nanowires/AAO composites fabricated by a simple approach
- Author
-
Lifeng Liu, Guanghui Rao, Jingbo Li, Marin Alexe, Seungwoo Lee, Woo Lee, JaeJong Lee, Weiya Zhou, and Ulrich Gösele
- Subjects
Materials science ,Scanning electron microscope ,Mechanical Engineering ,Silver iodide ,Nanowire ,Bioengineering ,General Chemistry ,Conductivity ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,Mechanics of Materials ,Electrical resistivity and conductivity ,Ionic conductivity ,General Materials Science ,Crystallite ,Electrical and Electronic Engineering ,Composite material - Abstract
AgI nanowires/anodic aluminum oxide ( AgI NWs/AAO) composites have been fabricated by a simple approach, which involves the thermal melting of AgI powders on the surface of the AAO membrane, followed by the infiltration of the molten AgI inside the nanochannels. As-prepared AgI nanowires have corrugated outer surfaces and are polycrystalline according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. X-ray diffraction (XRD) shows that a considerable amount of 7H polytype AgI exists in the composites, which is supposed to arise from the interfacial interactions between the embedded AgI and the alumina. AC conductivity measurements for the AgI nanowires/AAO composites exhibit a notable conductivity enhancement by three orders of magnitude at room temperature compared with that of pristine bulk AgI. Furthermore, a large conductivity hysteresis and abnormal conductivity transitions were observed in the temperature-dependent conductivity measurements, from which an ionic conductivity as high as 8.0 x 10(2) Omega(-1) cm(-1) was obtained at around 70 degrees C upon cooling. The differential scanning calorimetry (DSC) result demonstrates a similar phase transition behavior as that found in the AC conductivity measurements. The enhanced ionic conductivity, as well as the abnormal phase transitions, can be explained in terms of the existence of the highly conducting 7H polytype AgI and the formation of well-defined conduction paths in the composites.
- Published
- 2011
45. Site-specific multi-stage CVD of large-scale arrays of ultrafine ZnO nanorods
- Author
-
Dongshan Zhao, Xiaoxian Zhang, Huanli Dong, Mingyuan Gao, Weiya Zhou, and Sishen Xie
- Subjects
Fabrication ,Materials science ,Photoluminescence ,Silicon ,Mechanical Engineering ,Nucleation ,chemistry.chemical_element ,Bioengineering ,Nanotechnology ,General Chemistry ,Chemical vapor deposition ,Epitaxy ,chemistry ,Mechanics of Materials ,General Materials Science ,Nanorod ,Light emission ,Electrical and Electronic Engineering - Abstract
Multi-stage growth of ZnO nanorod arrays has been carried out by Au-assisted chemical vapor deposition (CVD) in order to better understand and more precisely control the growth behaviors. It is evidenced that Au-catalyzed vapor-liquid-solid (VLS) growth only dominates the initial site-specific nucleation of the nanorods, while the subsequent growth is governed by a vapor-solid (VS) epitaxy mechanism. The sequential VLS and VS behaviors permit the fabrication of large-scale highly ordered arrays of ZnO nanorods with precisely tunable diameters and embedded junctions by controlling reactant concentration and nanorod top morphology. Based on the above results, two routes to fabricate ultrafine ZnO nanorod arrays are proposed and stepwise nanorod arrays with ultrafine top segment (~10 nm in diameter) have been achieved. Temperature-dependent photoluminescence (PL) and spatial resolved PL were carried out on the nanorod arrays and on individual nanorods, indicating high quality optical properties and tunable light emission along the length of the stepwise nanorods.
- Published
- 2011
46. Small diameter carbon nanotubes synthesized in an arc-discharge
- Author
-
Xiaoping Zou, Zhuqin Liu, Sishen Xie, Gang Wang, Dongsheng Tang, Yubao Li, and Weiya Zhou
- Subjects
Nanotube ,Small diameter ,Materials science ,Carbon nanofiber ,Nanostructured materials ,chemistry.chemical_element ,General Chemistry ,Carbon nanotube ,law.invention ,Electric arc ,chemistry ,law ,General Materials Science ,Composite material ,Carbon - Published
- 2001
47. Aligned small α-SiC nanorods on β-SiC particles grown in an arc-discharge
- Author
-
Weiya Zhou, Gang Wang, Xiaoping Zou, Yubao Li, Zhuqin Liu, Guoda Lian, Dongsheng Tang, Sishen Xie, and Bingqing Wei
- Subjects
Materials science ,Nanostructure ,Nanostructured materials ,chemistry.chemical_element ,General Chemistry ,Substrate (electronics) ,Condensed Matter Physics ,Anode ,Electric arc ,Crystallography ,chemistry ,Chemical engineering ,Materials Chemistry ,Nanorod ,Nanometre ,Helium - Abstract
Aligned α-SiC nanorods, several nanometers in diameter and with lengths up to 200 nm, were grown on the facets of simultaneously formed β-SiC particles by using an SiC rod as the anode to arc-discharge in a helium atmosphere. SEM, TEM and XRD were employed to characterize the prepared nanostructures. The small α-SiC nanorods exhibit excellent elastic deformation ability and have a strong bond to the β-SiC substrate. The possible growth mechanism of the nanostructures is discussed.
- Published
- 2001
48. Nanographite ribbons grown from a SiC arc-discharge in a hydrogen atmosphere
- Author
-
Yubao Li, Gang Wang, Dongsheng Tang, Sishen Xie, Weiya Zhou, Zhuqin Liu, and Xiaoping Zou
- Subjects
Materials science ,Carbonization ,Electron energy loss spectroscopy ,Carbon-12 ,chemistry.chemical_element ,Diamond ,Nanotechnology ,General Chemistry ,Carbon nanotube ,engineering.material ,Catalysis ,law.invention ,chemistry ,law ,engineering ,Physical chemistry ,General Materials Science ,Graphite ,Boron - Abstract
[3] Banhart F, Ajayan M. Self-compression and diamond forma[12] Vignal V, Morawski AW, Konno H, Inagaki M. Quantitative tion in carbon onions. Adv Mater 1997;9(3):261–3. assessment of pores in oxidized carbon spheres using scan[4] Kang ZC, Wang ZL. Mixed-valent oxide-catalytic carbonizaning tunneling microscopy. J Mater Res 1999;14(3):1102– tion for synthesis of monodispersed nano sized carbon 12. spheres. Philos Mag B 1996;73:905–29. [13] Inagaki M, Vignal V, Konno H, Morawski AW. Effect of [5] Wang ZL, Kang ZC. Pairing of pentagonal and heptagonal carbonization atmosphere and subsequent oxidation on pore carbon rings in the growth of nanosize carbon spheres structure of carbon spheres observed by scanning tunneling synthesized by a mixed-valent oxide-catalytic carbonization microscopy. J Mater Res 1999;14(7):3152–7. process. J Phys Chem 1996;100:17725–31. [14] Auer E, Freund A, Pietsch J, Tacke T. Carbon as support for [6] Kang ZC, Wang ZL. On accretion of nanosize carbon industrial precious metal catalysts. Appl Catal spheres. J Phys Chem 1996;100:5163–5. 1998;173:259–71. [7] Wang ZL, Kang ZC. Graphitic structure and surface chemi[15] Flandrois S, Simon B. Carbon materials for lithium-ion cal activity of nanosized carbon spheres. Carbon rechargeable batteries. Carbon 1999;37:165–80. 1997;35(3):419–26. [16] Serp Ph, Figueiredo JL, Bertrand P, Issi J-P. Surface treat[8] Sharon M, Mukhopadhyay K, Yase K, Ijima S, Ando Y, Zhao ments of vapor-grown carbon fibers produced on a substrate. X. Spongy carbon nanobeads – a new material. Carbon Carbon 1998;36(12):1791–9. 1998;36(5–6):507–11. [17] Serin V, Brydson R, Scott A, Kihn Y, Abidate O, Maquin B [9] Inagaki M, Washiyama M, Sakai M. Production of carbon et al. Evidence for the solubility of boron in graphite by spherules and their graphitization. Carbon 1988;26(2):169– electron energy loss spectroscopy. Carbon 2000;38:547–54. 72. [18] Stephan O, Ajayan PM, Colliex C, Cyrot-Lackmann F, [10] Kamegawa K, Yoshida H. Preparation and characterization of Sandre E. Curvature-induced bonding changes in carbon swelling porous carbon beads. Carbon 1997;35(5):631–9. nanotubes investigated by electron energy-loss spectrometry. [11] Wang YG, Chang YC, Ishida S, Korai Y, Mochida I. Phys Rev B 1996;53(2):13824. Stabilization and carbonization properties of mesocarbon microbeads (MCMB) prepared from a synthetic naphthalene isotropic pitch. Carbon 1999;37(6):969–76.
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- 2001
49. Large third-order optical nonlinearity in directly synthesized single-walled carbon nanotube films
- Author
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Baohua Feng, Wenjun Ma, Sishen Xie, Yan Ren, Zhiqiang Niu, Haibo Dong, Weiya Zhou, Jinzhu Li, Qingsheng Zeng, and Xiaoxian Zhang
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Materials science ,business.industry ,Biomedical Engineering ,Bioengineering ,General Chemistry ,Carbon nanotube ,Condensed Matter Physics ,Laser ,law.invention ,Condensed Matter::Materials Science ,Third order ,Optical nonlinearity ,Nonlinear system ,Optics ,law ,Optoelectronics ,General Materials Science ,business ,Ultrashort pulse - Abstract
Large third-order optical nonlinearity is observed in single-walled carbon nanotube (SWNT) films that are directly synthesized by CVD method rather than post-deposited from solution. Through z-scan method, the third-order nonlinear susceptibility (chi((3))) is measured, and the vertical bar Im chi((3))vertical bar is 1.8 x 10(-7) esu at 1064 nm, which is among the highest reported values for optical nonlinear materials. Combined with their transparent morphology and ultrafast carrier relaxation time, our results indicate the promising prospect of directly synthesized SWNT films as saturable absorbers using in mode-lock lasers or ultrafast switching materials in optical telecommunications.
- Published
- 2010
50. Template synthesis and growth mechanism of metal nanowire/carbon nanotube heterojunctions
- Author
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Weiya Zhou, Zhiqiang Niu, Haibo Dong, Wenjun Ma, Qingsheng Zeng, Xiaoxian Zhang, Sishen Xie, and Jinzhu Li
- Subjects
Materials science ,Nanostructure ,Biomedical Engineering ,Nanowire ,chemistry.chemical_element ,Bioengineering ,Nanotechnology ,Heterojunction ,General Chemistry ,Carbon nanotube ,Chemical vapor deposition ,Condensed Matter Physics ,Amorphous solid ,law.invention ,Amorphous carbon ,chemistry ,law ,General Materials Science ,Carbon - Abstract
Copper (Cu) and Cobalt (Co) with remarkable difference in the catalytic activity for the growth of carbon nanotubes (CNTs) have been used to prepare metal-nanowire/CNT heterojunctions. The ordered arrays of Cu nanowire/CNT (CuNW/CNT) and Co nanowire/CNT (CoNW/CNT) heterojunctions were prepared by combining electrochemical deposition and chemical vapor deposition. The interfaces between CNTs and Cu or Co nanowires have been examined and compared. At the interface of CuNW/CNT heterojunction, the tip of CuNW is encapsulated by carbon material (named "cap") and connected the CNT consisting of amorphous carbon (a-C). Two-segment CuNW/amorphous CNT (CuNW/a-CNT) hybrid nanostructure was obtained for the CuNW/CNT heterojunctions due to low catalytic activity of Cu. It is also interesting that a hollow gap was observed between the "cap" and the CuNW. By contrast with the case of Cu, multi-walled CNT (MWCNT) was achieved and no hollow gap was observed at the interface of CoNW/CNT heterojunctions. Three-segment CoNW/MWCNT/a-CNT hybrid nanostructure was observed for the CoNW/CNT heterojunctions because of high catalytic activity of Co. Because no stable copper carbides are observed, we infer that the growth mechanism of CuNW/CNT heterojunctions is different from that of CoNW/CNT. Possible growth models of CuNW/CNT and CoNW/CNT heterojunctions are proposed based on experimental results, respectively.
- Published
- 2010
Catalog
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