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Development of a fully automated desktop chemical vapor deposition system for programmable and controlled carbon nanotube growth
摘要： We have rationally designed and developed a fully automated desktop furnace system that enables programmable chemical vapour deposition growth of carbon nanotubes with controlled height, density, and pattern architecture. Comprising several essential components involving a heating furnace, mass flowmeters, and computer controller, the developed system realizes controlled and practical carbon nanotube growth without resort to expensive and ponderous instruments. By programming, modifying, and loading the reusable recipes in the developed system, systematic and reproducible growths of carbon nanotubes with desired morphology and dimension can be performed. Growth results with controlled height, density, and pattern are demonstrated through the actual operations, confirming the validity and usefulness of the developed system towards various practical applications.
关键词： Furnace,Programmable growth recipe,Desktop system,Chemical vapor deposition,Micropattern,Automated control,Nanopattern,Carbon nanotube
更新于2025-09-16 10:30:52
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Synthesis of Porous ZnO Nanosheets and Carbon Nanotube Hybrids as Efficient Photocatalysts via Pulsed Laser Ablation
摘要： Zinc oxide (ZnO) has attractive photocatalytic properties. However, the high recombination rate of the photo-excited charge carriers on this material often restricts application. Here, we report that hybridization of one dimensional (1D) carbon nanotubes (CNT) on two dimensional (2D) porous ZnO nanosheets (NS) can be a promising strategy to overcome some of the challenges of ZnO. Specifically, a pulsed laser ablation technique was utilized to hybridize 1D CNT with 2D porous ZnO NS in environmentally friendly as well as super-economic (short time, less than 10 min) conditions. The synthesized ZnO NS-CNT hybrids show a significantly enhanced photocatalytic activity for water splitting relative to their counterpart ZnO NS.
关键词： pulsed laser ablation,water splitting,carbon nanotube,photocatalyst,zinc oxide,nanocomposites
更新于2025-09-16 10:30:52
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Tunable Assembly of Superfine Single-Walled Carbon Nanotube Fibers
摘要： We have developed a method of spinning super?ne single-walled carbon nanotube (SWNT) ?bers to facilitate their assembly in 2D counter microelectrode array via alternating current (AC) dielectrophoresis (DEP) by using clean, combination of ionic surfactants, and stable SWNT aqueous high-quality solutions. Our method can attract metallic SWNTs (M_SWNTs) toward a counter microelectrode array, resulting in an opposite movement of semiconducting SWNTs (S_SWNTs) and leaving S_SWNTs in the suspension by taking advantages of the differences in the relative dielectric constants of M_SWNTs and S_SWNTs with respect to the suspension and substrate-bent AC DEP structure. Our method can also control the stretching or relaxed extent and diameters of the suspended SWNT ?bers by tuning the bending degree of a ?exible substrate, AC frequency, peak value of AC voltage, and time. The effectiveness of the method is proven by the electrical measurement result, scanning electron microscopy image, atomic force microscope image and Raman spectroscopy on test samples.
关键词： Tunable assembly,single-walled carbon nanotube (SWNT) ?bers,alternating current (AC) dielectrophoresis,substrate-bent
更新于2025-09-16 10:30:52
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Extremely Efficient Photocurrent Generation in Carbon Nanotube Photodiodes Enabled by a Strong Axial Electric Field
摘要： Carbon nanotube (CNT) photodiodes have potential to convert light into electrical current with high efficiency. However, previous experiments have revealed photocurrent quantum yield (PCQY) well below 100%. In this work, we show that axial electric field increases the PCQY of CNT photodiodes. In optimal conditions our data suggest PCQY > 100%. We studied, both experimentally and theoretically, CNT photodiodes at room temperature using optical excitation corresponding to the S22, S33 and S44 exciton resonances. The axial electric field inside the pn junction was controlled using split gates that are capacitively coupled to the suspended CNT. Our results give new insight into the photocurrent generation pathways in CNTs, and the field dependence and diameter dependence of PCQY.
关键词： scanning photocurrent microscopy,carbon nanotube,carrier multiplication,exciton dissociation
更新于2025-09-16 10:30:52
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Optically Modulated Tunable O-Band Praseodymium-Doped Fluoride Fiber Laser Utilizing Multi-Walled Carbon Nanotube Saturable Absorber <sup>*</sup>
摘要： A tunable and optically modulated fiber laser utilizing a multi-walled carbon nanotube based saturable absorber is demonstrated for operation in the O-band region. A praseodymium-doped fluoride fiber is used as the gain medium and the system is capable of generating modulated outputs at 1300 nm. Pulsed output is observed at pump powers of 511 mW and above, with repetition rates and pulse widths that can be tuned from 41 kHz and 3.4 ??s to 48 kHz and 2.4 ??s, respectively, at the maximum pump power available. A maximum average output power of 100 ??W with a corresponding single pulse energy of 2.1 nJ is measured, while the tunability of the proposed laser is from 1290 nm to 1308 nm. The output is stable, with peak power fluctuations of ～4 dB from the average value.
关键词： tunable fiber laser,O-band,praseodymium-doped fluoride fiber,multi-walled carbon nanotube,saturable absorber
更新于2025-09-16 10:30:52
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Effect of ultrasonic treatment on the properties of multiwalled carbon nanotubes – polymethylmethacrylate composites: Effect of applied voltage and pressure on conductivity of the composites
摘要： The effect of sonication time during the synthesis of multiwalled carbon nanotubes – polymethylmethacrylate (MWCNT/PMMA) composites by coagulation technique on the MWCNT distribution in the bulk of the composites close to the percolation threshold was systematically studied by SEM and by measurements on specific resistivity in a wide range of voltages and external pressure. It was found that the resistivity of composites is irreversibly reduced up to 105 times during the first 1–3 measurements, while further measurements are characterized by high repeatability. Change of the composite resistivity during the measurements is discussed assuming that several types of contacts between the nanotubes changing during the measurement are present. It was found that an increase of the sonication time changed the ratio between ohmic and non-ohmic contacts. It affected the type of changes in the sample resistivity during the voltage variation in the range of 0–103 V/mm and resulted in a nonuniform dependence of the composite specific resistivity on the sonication time. An increase of the composite volume during the resistivity measurements was observed at the current densities above 4·10–8 A/cm2. New ohmic contacts were found to form when external pressure was applied due to squeezing of the polymer matrix from the space between adjacent nanotubes.
关键词： multiwalled carbon nanotube,nanocomposites,contacts between nanotubes,current-voltage characteristic,polymethylmethacrylate
更新于2025-09-16 10:30:52
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Ho <sup>3+</sup> -Doped All-Fiber Laser Q-Switched by D-Shaped Fiber Carbon-Nanotube Saturable Absorber
摘要： D-shaped fiber deposited with single-wall carbon-nanotubes was used as fiber-optic saturable absorber to achieve Q-switched Ho3+-doped fluoride fiber laser in all-fiber configuration with superior compactness and reliability. Stable Q-switched operation at 1192 nm was established at the pump power of 290 mW. When the pump power was increased to 1280 mW, Q-switched laser with a pulse duration of 1.1 μs and pulse energy of 0.11 μJ at a repetition rate of 127 kHz was obtained. This all-fiber laser exhibits high stability with a radio-frequency signal-to-noise ratio > 50 dB.
关键词： Fiber laser,Q-switched,carbon nanotube,fluoride fiber
更新于2025-09-16 10:30:52
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The synthesis of Co <sub/>x</sub> Ni <sub/>1?x</sub> Fe <sub/>2</sub> O <sub/>4</sub> /multi-walled carbon nanotube nanocomposites and their photocatalytic performance
摘要： A series of CoxNi1?xFe2O4/multi-walled carbon nanotube (CoxNi1?xFe2O4/MWCNTs) nanocomposites as photocatalysts were successfully synthesized, where CoxNi1?xFe2O4 was synthesized via a one-step hydrothermal approach. Simultaneously, methylene blue (MB) was used as the research object to investigate the catalytic effect of the catalyst in the presence of hydrogen peroxide (H2O2). The results showed that all the photocatalysts exhibited enhanced catalytic activity compared to pure ferrite. In addition, compared with the other photocatalysts, the reaction time was greatly shortened a significantly higher removal rate was achieved using 3-CNF/MWCNTs. There was no significant decrease in photodegradation efficiency after three catalytic cycles, suggesting that CoxNi1?xFe2O4/MWCNTs are recyclable photocatalysts for wastewater treatment. Our results indicate that the CoxNi1?xFe2O4/MWCNT composite can be effectively applied for the removal of organic pollutants as a novel photocatalyst.
关键词： methylene blue,photocatalysts,hydrothermal approach,wastewater treatment,multi-walled carbon nanotube,hydrogen peroxide,CoxNi1?xFe2O4
更新于2025-09-16 10:30:52
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Single-walled carbon nanotube growth at low temperature by alcohol gas source method using Co catalyst: enhancement effects of Al<sub>2</sub>O<sub>3</sub> buffer layer on carbon nanotube yield
摘要： Using an alcohol gas source chemical vapor deposition method, we attempted to grow single-walled carbon nanotube (SWCNT) growth using Co catalysts on Al2O3 buffer layers. Reducing the growth temperature decreased the optimal ethanol pressure to obtain the highest SWCNT yield. By optimizing the ethanol pressure, we succeeded in growing SWCNTs at 400oC. Irrespective of the growth temperature, SWCNT yields from Co catalysts on Al2O3 buffer layers were higher than those on SiO2/Si substrates, but the enhancing effects of Al2O3 buffer layers on SWCNT yield were reduced below 500oC. Taking into account both in-plane X-ray diffraction results and decrease of catalyst aggregation in the low temperature region, we concluded that the density of Co particles suitable for SWCNT growth increased on SiO2 surface at low temperature, resulting in the reduction of difference in SWCNT yield at low temperature between Al2O3 buffer layers and SiO2/Si substrates.
关键词： catalyst,CVD,low-temperature growth,single-walled carbon nanotube,Co
更新于2025-09-16 10:30:52
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Simulation of quantum transport in doped carbon nanotube diode controlled by transverse electric field
摘要： Using first-principle and semi-empirical methods, optical responses and transport characteristics of hybrid CNT-based diodes are studied. The junction is realized by a combination of doping of one half of a nanotube and applying a transverse electric field to the other. Calculations are carried out in the framework of the density functional theory and the nonequilibrium Green function method. The possibility of using these rectifiers in optical nanoantennas is discussed.
关键词： density functional theory,nonequilibrium Green function method,transverse electric field,doped carbon nanotube diode,quantum transport,optical nanoantennas
更新于2025-09-16 10:30:52