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Carbon Nanotubes-Wrapped Urchin-Like Bi <sub/>2</sub> S <sub/>3</sub> Composites with Enhanced Photocatalytic Performance
摘要： The urchin-like Bi2S3/carbon nanotubes (Bi2S3 urchin/CNTs) composites were successfully synthesized by a microwave method. X-ray diffraction (XRD), Fourier Transform infrared spectra (FTIR), Raman spectra, diffused reflectance spectra (DRS) were used for the characterization of the obtained photocatalysts. The SEM and TEM morphology of Bi2S3 urchin/CNTs composites showed that urchin-like nanoparticles were assembled by many nanorods which grew radially from the center and nanorods were wrapped with CNTs on their end. The photocatalytic performance was studied by the degradation of methyl orange (MO) under visible light and the photodegradation efficiency of Bi2S3 urchin/CNTs hybrid materials exhibited significantly excellent photocatalytic activity. A possible mechanism for the photodegradation of MO was also suggested.
关键词： Photocatalysts.,Carbon Nanotubes
更新于2025-09-04 15:30:14
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Synthesis and Characterization of Carbon Nanotubes by Modified Flame Fragments Deposition Method
摘要： This study focuses on the synthesis of carbon nanotubes from Iraqi natural gas via a modified flame fragments deposition method in presence and absence of the catalyst. Four types of catalysts were used for the growth of carbon nanotubes. These types are iron doped on magnesium oxide (Fe/MgO), iron-cobalt doped on calcium carbonate (Fe-Co/CaCO3) and iron(III) oxide. All these four types were prepared in one batch by a home made instrument.The implemented technique ensures the same experimental conditions such as type of carbon source, type of carrier gas, flow rate of gases, growth temperature and synthesis time of growth for all synthesized samples. Various experimental techniques viz., X-ray diffraction, Raman spectroscopy, scanning electron microscopy and thermogravimetric analysis were used for characterization of the synthesized carbon nanotubes.
关键词： Flame fragments deposition,Natural gas,Carbon nanotubes
更新于2025-09-04 15:30:14
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Quartz Tuning‐Fork Based Carbon Nanotube Transfer into Quantum Device Geometries
摘要： With the objective of integrating single clean, as-grown carbon nanotubes into complex circuits, we have developed a technique to grow nanotubes directly on commercially available quartz tuning forks using a high-temperature chemical vapor deposition process. Multiple straight and aligned nanotubes bridge the >100 mm gap between the two tips. The nanotubes are then lowered onto contact electrodes, electronically characterized in situ, and subsequently cut loose from the tuning fork using a high current. First quantum transport measurements of the resulting devices at cryogenic temperatures display Coulomb blockade characteristics.
关键词： carbon nanotubes,transfer,device fabrication
更新于2025-09-04 15:30:14
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Influence of Water Molecules on the Detection of Volatile Organic Compounds (VOC) Cancer Biomarkers by Nanocomposite Quantum Resistive Vapor Sensors vQRS
摘要： The anticipated diagnosis of various fatal diseases from the analysis of volatile organic compounds (VOC) biomarkers of the volatolome is the object of very dynamic research. Nanocomposite-based quantum resistive vapor sensors (vQRS) exhibit strong advantages in the detection of biomarkers, as they can operate at room temperature with low consumption and sub ppm (part per million) sensitivity. However, to meet this application they need to detect some ppm or less amounts of biomarkers in patients' breath, skin, or urine in complex blends of numerous VOC, most of the time hindered by a huge amount of water molecules. Therefore, it is crucial to analyze the effects of moisture on the chemo-resistive sensing behavior of carbon nanotubes based vQRS. We show that in the presence of water molecules, the sensors cannot detect the right amount of VOC molecules present in their environment. These perturbations of the detection mechanism are found to depend on the chemical interactions between water and other VOC molecules, but also on their competitive absorption on sensors receptive sites, located at the nanojunctions of the conductive architecture. This complex phenomenon studied with down to 12.5 ppm of acetone, ethanol, butanone, toluene, and cyclohexane mixed with 100 ppm of water was worth to investigate in the prospect of future developments of devices analysing real breath samples in which water can reach a concentration of 6%.
关键词： conductive polymer nanocomposites,anticipated diagnosis,effects of humidity,VOC,quantum resistive vapor sensors,functionalized carbon nanotubes,biomarkers detection
更新于2025-09-04 15:30:14
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Bipolar Thermoelectric Effects in Semiconducting Carbon Nanotubes: Description in Terms of One-Dimensional Dirac Electrons
摘要： The thermoelectric effects in semiconducting single-walled carbon nanotubes (SWCNTs) are investigated based on the linear response theory combined with the thermal Green’s function method. It is shown that the electronic states near the lowest conduction band minimum and the highest valence band maximum can be effectively described in terms of one-dimensional (1D) Dirac electrons to which a theoretical scheme is developed to describe the thermoelectric responses making it possible to study the effects of inter-band impurity scattering and in-gap states. Using the proposed scheme, the bipolar thermoelectric effects (i.e., the sign inversion of the Seebeck coefficient) in semiconducting SWCNTs observed in recent experiments are explained. Moreover, the temperature dependence of the Seebeck coefficient of semiconducting SWCNTs at low temperature is clarified.
关键词： thermal Green’s function method,Seebeck coefficient,linear response theory,Dirac electrons,semiconducting single-walled carbon nanotubes,thermoelectric effects
更新于2025-09-04 15:30:14
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Thermal and electrical conductivity enhancement of solar glycol-water mixture containing MWCNTs
摘要： In this investigation, the authors describe the thermal conductivity, and electrical conductivity of solar glycol - water (50:50) mixture with MWCNTs. Gum Arabic was used as the surfactant to prepare a stable nanofluid suspension. The MWCNTs are dispersing with different volume concentrations of 0.2%, 0.4% and 0.6% prepared via a typical two-step methodology. The colloidal stability assessments were conducted through UV-vis spectrometer, zeta potential analyser, scanning electron microscopy analysis and pH metre. The maximum augmentation of thermal conductivity attained is (cid:1)21.46% at a loading of 0.6 vol.% of MWCNTs in SG - water mixture at 50(cid:3)C. However, the electrical conductivity of the prepared nanofluid linearly enhanced with increasing temperature. The electrical conductivity enhancements of (cid:1)62.19% at a loading of 0.6 vol.% of MWCNTs in SG – water mixture at 50?C. Results confirm that the SG-Water and MWCNTs based nanofluids can be used as a right replacement for the conventional liquids in various heat transfer applications.
关键词： Solar glycol,Thermal conductivity,Multiwalled carbon nanotubes,pH,Electrical conductivity
更新于2025-09-04 15:30:14
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Effect of Polyethylene Glycol Surface Charge Functionalization of SWCNT on the in vitro and in vivo Nanotoxicity and Biodistribution Monitored Noninvasively using MRI
摘要： The current study evaluated in vitro and in vivo toxicity of carboxyl or amine PEG surface functionalization of single walled carbon nanotubes (SWCNTs). Assessments of cytotoxicity, genotoxicity, immunotoxicity and oxidative stress were performed in vitro and in vivo (in a one-month follow-up study). The SWCNT biodistribution was investigated using noninvasive MRI. Results confirmed the enhanced biocompatibility of PEG-functionalized SWCNTs compared to non-functionalized materials with significant decreases (p<0.05) in the percentage of cell viability and increases in ROS generation, mitochondrial membrane potential, cell apoptosis, oxidative stress generation and oxidative DNA damage in vitro. PEG-functionalized SWCNTs with amine terminals were found to induce prominent increases in ROS generation, mitochondrial membrane potential, and oxidative stress compared to carboxy functionalized SWCNTs. No significant difference in the biodistribution of either PEG-COOH or PEG-NH2 functionalized SWCNTs was observed in MRI. In vivo assessments revealed a statistically significant increase (p<0.05) in oxidative stress as early as 24 h in serum and liver; however, all values normalized at 2 weeks’ investigation time point. DNA damage was minimal with either PEG-COOH or PEG-NH2 functionalized SWCNTs after two weeks’ exposure. The negatively charged SWCNTs caused lesser DNA damage compared to positively charged samples. Carboxy-functionalized SWCNTs did not caused substantial changes in inflammatory mediators and were found to be significantly safer than non-functionalized SWCNTs and may pave the way for novel biomedical applications in cancer diagnosis and therapy.
关键词： Nanotoxicity,Cytotoxicity,Carbon nanotubes,In vivo biodistribution,Magnetic Resonance Imaging
更新于2025-09-04 15:30:14