- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Optical properties of chiral single-walled carbon nanotubes thin films
摘要： This work contains experimental results of optical properties for thin films containing Single-Walled Carbon Nanotubes. Thin films concerning 0.5, 1 and 2 mg of low dimension chiral (10,6) Single-Walled Carbon Nanotubes dispersed in low concentration aqueous sodium dodecyl sulfate solution (2 mL) were successfully fabricated by spin-coating technique on transparent substrates at ambient atmosphere. Optical properties of these thin films were examined using Transmission, Raman and Photoluminescence Spectroscopies. We find that investigated chiral Single-Walled Carbon Nanotubes show transmission and emission bands not only in infrared range but also ultraviolet and visible range.
关键词： Absorbance,Single-walled carbon nanotubes,Raman spectra,Photoluminescence,Decay time of photoluminescence,Quantum yield
更新于2025-09-11 14:15:04
-
Kinking effects and transport properties of coaxial BN-C nanotubes as revealed by <i>in situ</i> transmission electron microscopy and theoretical analysis
摘要： The insights into transport behavior and the effects of bending on heterostructures constructed from boron nitride (BN) and carbon (C) nanotubes are important for their flexible device applications because the two systems have equally excellent mechanical but completely different electrical properties. In this work, coaxial BN–C nanotubes have been fabricated and their intrinsic transport properties, as well as structural and electrical response to bending deformation, are studied inside a high-resolution transmission electron microscope. Ballistic, diffusive, and hopping transports within different tube length ranges have been observed. When bending deformation was applied to the tubes, although severe kinking becomes apparent, their transport properties are not notably affected. Meanwhile, both theoretical and experimental analyses confirm that the kink positions depend on the ratio of tube diameter to its length. Possible formation of quantum dots, directly within the kink areas, was predicted through calculations of electron density redistribution between nanotube walls at bending.
关键词： bending deformation,transport properties,BN-C nanotubes,in situ TEM,quantum dots
更新于2025-09-11 14:15:04
-
Influence of PbS Quantum Dots-Doped TiO2 Nanotubes in TiO2 Film as an Electron Transport Layer for Enhanced Perovskite Solar Cell Performance
摘要： Lead sulfide quantum dots-doped titanium dioxide nanotubes (PbS QDs-doped TNTs) were successfully prepared by the hydrothermal and impregnation methods. A thin layer of titanium dioxide (TiO2) comprising of PbS QDs-doped TNTs was applied as an electron transport layer (ETL) in order to improve the planar perovskite solar cell efficiency. The role of incorporating a high surface area of one-dimensional nanotube structure of TiO2 in the conventional TiO2 layer provided a special unidirectional charge transport and a high charge collection. Moreover, doping PbS QDs onto the surface of TNTs modified the electronic and optical properties of the ETL by downshifting the conduction band of TiO2 from ?4.22 to ?4.58 eV, therefore promoting the driving force of an electron injection to the transparent conductive electrode. By varying the concentration of PbS QDs-doped TNTs dispersed in 2-butanol from 0.1 to 0.9 mg/mL, a concentration of 0.3 mg/mL PbS QDs-doped TNTs was the optimum concentration to be mixed with TiO2 solution for the ETL deposition. The best perovskite solar cell performance with the optimum loading of PbS QDs-doped TNTs provided 14.95% power conversion efficiency, which was increased from 12.82% obtained from the cell with pristine TiO2 film as ETL.
关键词： PbS quantum dots (PbS QDs),perovskite solar cells (PSCs),TiO2 nanotubes (TNTs),Electron transport layer (ETL)
更新于2025-09-11 14:15:04
-
Additional obstacles in carbon nanotube growth by gas-flow directed chemical vapour deposition unveiled through improving growth density
摘要： Here, we demonstrate an approach of increasing the density of ultralong carbon nanotubes (CNTs) growth by combining fast-heating method developed by Huang et al. (J. Am. Chem. Soc., 2003, 125, 5636–5637) with catalyst support engineering. Specifically, using graphene oxide as a catalyst support for iron oxide (Fe3O4) catalyst nanoparticles, we achieved high density growth of CNTs grown by the “kite-mechanism”. Our analysis revealed that the fast-heating method reduced undesired aggregation of the catalyst nanoparticles, which has been reported to be a primary limiation mechanism, by shortening the time between substrate heating and CNT growth. In addition, the use of graphene oxide support worked to controllably and uniformly disperse catalyst nanoparticles in relatively high density which provided increased process control by extending the time before the onset of catalyst aggregation. Together, these approaches suppressed the aggregation of the catalyst nanoparticles, which facilitated the “tip-growth” mode instead of “root-growth” mode, and led to the high density growth of ultralong CNTs. Our results also indicate additional limitations and complexities on the high density CNT growth by the kite-growth approach, which limit high density synthesis.
关键词： graphene oxide,catalyst support engineering,fast-heating method,carbon nanotubes,chemical vapour deposition
更新于2025-09-11 14:15:04
-
Multifunctional Effect of <i>p</i> ‐Doping, Antireflection, and Encapsulation by Polymeric Acid for High Efficiency and Stable Carbon Nanotube‐Based Silicon Solar Cells
摘要： Silicon solar cells among different types of solar energy harvesters have entered the commercial market owing to their high power conversion efficiency and stability. By replacing the electrode and the p-type layer by a single layer of carbon nanotubes, the device can be further simplified. This greatly augments the attractiveness of silicon solar cells in the light of raw material shortages and the solar payback period, as well as lowering the fabrication costs. However, carbon nanotube-based silicon solar cells still lack device efficiency and stability. These can be improved by chemical doping, antireflection coating, and encapsulation. In this work, the multifunctional effects of p-doping, antireflection, and encapsulation are observed simultaneously, by applying a polymeric acid. This method increases the power conversion efficiency of single-walled carbon nanotube-based silicon solar cells from 9.5% to 14.4% and leads to unprecedented device stability of more than 120 d under severe conditions. In addition, the polymeric acid-applied carbon nanotube-based silicon solar cells show excellent chemical and mechanical robustness. The obtained stable efficiency stands the highest among the reported carbon nanotube-based silicon solar cells.
关键词： doping,carbon nanotubes,silicon solar cells,antireflection,Nafion
更新于2025-09-11 14:15:04
-
Neutron Activated <sup>153</sup> Sm Sealed in Carbon Nanocapsules for <i>In Vivo</i> Imaging and Tumor Radiotherapy
摘要： Radiation therapy along with chemotherapy and surgery remain the main cancer treatments. Radiotherapy can be applied to patients externally (external beam radiotherapy) or internally (brachytherapy and radioisotope therapy). Previously, nanoencapsulation of radioactive crystals within carbon nanotubes, followed by end-closing, resulted in the formation of nanocapsules that allowed ultrasensitive imaging in healthy mice. Herein we report on the preparation of nanocapsules initially sealing ‘cold’ isotopically enriched samarium (152Sm), which can then be activated on demand to their ‘hot’ radioactive form (153Sm) by neutron irradiation. The use of ‘cold’ isotopes avoids the need for radioactive facilities during the preparation of the nanocapsules, reduces radiation exposure to personnel, prevents the generation of nuclear waste and evades the time constraints imposed by the decay of radionuclides. A very high specific radioactivity is achieved by neutron irradiation (up to 11.37 GBq/mg), making the ‘hot’ nanocapsules useful not only for in vivo imaging but also therapeutically effective against lung cancer metastases after intravenous injection. The high in vivo stability of the radioactive payload, selective toxicity to cancerous tissues and the elegant preparation method offer a paradigm for application of nanomaterials in radiotherapy.
关键词： nuclear imaging,filled carbon nanotubes,nanoencapsulation,nanooncology,radiooncology,cancer therapy
更新于2025-09-11 14:15:04
-
Nonlinear mixing of lasers and terahertz generation on CNT embedded metal surface
摘要： A scheme of terahertz generation, employing carbon nanotubes (CNTs) embedded metal surface is proposed. The surface is irradiated by two laser beams at angle of incidence θ. The lasers exert a ponderomotive force on CNT electrons at the beat frequency ω=ω1-ω2 and produce a nonlinear current, turning the nanotubes into an array of antennae emitting beat frequency THz radiation. The THz ?eld is resonantly enhanced at the plasmon resonance, =ω ω β/2 p , where ωp is the plasma frequency of the CNT electrons and β is a parameter that characterizes the metallic susceptibility of the CNTs. The collisions are a limiting factor and cause heating of CNTs.
关键词： Terahertz generation,Carbon nanotubes,Ponderomotive force,Nonlinear mixing
更新于2025-09-11 14:15:04
-
Photo‐controlled Dopamine Polymerization on DNA Origami with low Nanometer Resolution
摘要： Temporal and spatial control over polydopamine formation on the nanoscale can be achieved by installing an irradiation-sensitive polymerization system on DNA origami. Precisely distributed G-quadruplex structures on the DNA template serve as anchors for embedding the photosensitizer protoporphyrin IX, which — upon the irradiation with visible light — induces a multistep oxidation from dopamine to polydopamine, producing polymeric structures on designated areas within the origami framework. The photochemical polymerization process allows the exclusive control over polydopamine layer formation, which is adjusted by simply switching the light source on and off. The obtained polymer–DNA hybrid material shows significantly enhanced stability properties paving the way for biomedical and chemical applications that are commonly prohibited by the sensitivity of DNA.
关键词： DNA origami,DNA nanotubes,Photopolymerization,Polydopamine,Stability in water
更新于2025-09-11 14:15:04
-
Improved Laser‐Based Photoluminescence on Single‐Walled Carbon Nanotubes
摘要： Photoluminescence (PL) is a common tool to characterize various properties of single-walled carbon nanotube (SWCNT) chirality distribution and the level of tube individualization in SWCNT samples. Most PL studies use conventional lamp light sources whose spectral distribution is filtered with a monochromator, but this results in a still impure spectrum with a low spectral intensity. Tunable dye lasers offer a tunable light source which cover the desired excitation wavelength range with a high spectral intensity, but their operation is often cumbersome. Herein, the design and properties of an improved dye-laser system which is based on a Q-switch pump laser are presented. The high peak power of the pump provides an essentially threshold-free lasing of the dye laser, which substantially improves the operability. It allows operation with laser dyes, such as Rhodamin 110 and Pyridin 1, which are otherwise on the border of operation of the laser. The system allows to cover the 540–730 nm wavelength range with four dyes. In addition, the dye laser output pulses closely follow the properties of the pump, which directly provides a time-resolved and tunable laser source. The performance of the system by measuring the PL map of a HiPco SWCNTs sample is demonstrated.
关键词： photoluminescence,carbon nanotubes,spectrometers,pulsed dye lasers
更新于2025-09-11 14:15:04
-
Regrowth and catalytic etching of individual single-walled carbon nanotubes studied by isotope labeling and growth interruption
摘要： To realize the efficient growth of single-walled carbon nanotubes (SWCNTs), the growth mechanism behind catalyst activity and growth rates needs to be elucidated at the single nanotube level. In this study, we synthesized SWCNTs with growth interruption, where only Ar, Ar/H2, or Ar/H2/H2O was introduced during a pause in the supply of a carbon source, in order to examine the effects of additive molecules in a chemical vapor deposition process. This interrupted growth was performed in combination with an isotope labeling technique to show the time evolution of individual SWCNT growth. While the introduction of Ar during the growth interruption tended to terminate SWCNT growth, the introduction of Ar/H2 resulted in the regrowth of SWCNTs once ethanol was reintroduced. When interrupted with Ar/H2/H2O, SWCNTs were etched catalytically while sliding themselves in the reverse direction of growth and, then, regrew. Raman analysis revealed that the chirality of SWCNTs was preserved even after etching and regrowth. The growth rates of SWCNTs were unchanged before and after the interruption in the case of Ar/H2, but they were increased by a factor of ~1.7 in the case of Ar/H2/H2O. These results provide effective means to maintain the catalyst activity and to enhance growth rates.
关键词： Isotope labeling,Catalytic etching,Single-walled carbon nanotubes,Growth interruption,Chemical vapor deposition
更新于2025-09-11 14:15:04