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Synthesis and Optical Properties of Iodinated Multi-walled Carbon Nanotubes
摘要： This paper reports synthesis and optical properties of iodinated multi-walled carbon nanotubes (MWCNT). Multi-walled carbon nanotubes were synthesized by aerosol – assisted chemical vapor deposition method and iodinated by crystalline iodine under increased pressure (approximately ~20 bar) at 400°C. X-ray diffraction analysis, Raman and Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy were applied to characterize the iodinated MWCNTs.The results proved the presence of iodine atoms in iodinated MWCNTs. UV-VIS absorption and photoluminescence properties have been studied in pristine MWCNTs and iodinated MWCNTs suspensions in ethanol. Firstly, photoluminescence intensity of the iodinated MWCNTs remarkably enhanced with the appearance of C–I bonds on the surface of MWCNTs, due to the high concentration of intercalated iodine atoms (approximately 30 wt %). The photoluminescence intensity enhancement of peaks at 430 and 520 nm is highly dependent on defects formed by C–I bonds.
关键词： C–I bonds,photoluminescence,iodinated multi-walled carbon nanotubes,optical properties
更新于2025-11-19 16:56:42
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State-of-the art non-destructive techniques for defects detection in nanocomposites foam-core sandwich panels containing carbon nanotubes: IR thermography and microwave imaging
摘要： In this article, the state-of-the art of infrared (IR) thermography and microwave non-destructive (NDT) testing for inspection of defects in carbon nanotubes-based nanocomposite sandwich panels has been presented. Di?erent types of defects such as holes, notches and inclusion (Te?on) have been simulated in the polymeric foam-core of sandwich panels. The infrared (IR) thermography and microwave methods have been conducted to assess the simulated defects in the sandwich panel. The thermography results revealed that the thermal energy absorbance was higher in sandwich panel containing multi-walled carbon nanotubes (MWCNTs), however, various types of defects were well detected in both specimens with and without MWCNTs. From the result of microwave imaging, the same probability of NDT inspection was observed for detecting subsurface defects in sandwich panel and its nanocomposites. The use of low content of MWCNT (0.5 wt%) did not signi?cantly a?ect on the microwave absorption properties of sandwich panel among NDT procedure, however some changes of re?ection coe?cient amplitude in selected frequency bands were observable.
关键词： Multi-walled carbon nanotubes,Sandwich structures,Non-destructive testing,Nanocomposites
更新于2025-09-23 15:23:52
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Graphene Nanoribbons from Electrostatic-Force-Controlled Electric Unzipping of Single- and Multi-Walled Carbon Nanotubes
摘要： An electrostatic forces (EF) controlled electric unzipping method was developed for producing graphene nanoribbon (GNR) from both the single- (SWCNT) and multi-walled carbon nanotubes (MWCNT). Experimentally, an electrostatic generator was employed by taking its two electrodes with oppositely charges to alternatively link to the metal vessel and the CNT/water solution to form two oppositely electric cycles corresponding to the EF in enhancement or reduction, respectively. Transmission electron microscopy images showed that this applied method can unzip both the SWCNT and MWCNT into relative GNRs. During the EF-controlled electric unzipping process, the concentration increase and EF-controlled in reduction model can produce GNR with enhanced width and quality.
关键词： electrostatic forces control,graphene nanoribbon,Single- and multi-walled carbon nanotubes,electric unzipping,width and quality
更新于2025-09-23 15:19:57
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Preparation method and underlying mechanism of MWCNTs/Ti6Al4V nanocomposite powder for selective laser melting additive manufacturing
摘要： The fabrication of high-performance metal matrix nanocomposites is a new development direction in laser additive manufacturing (AM); however, the unique localized line-by-line and layer-by-layer forming process of AM has special requirements on the applicable powder materials for AM. The feedstock powder preparation is an important factor in laser AM, especially the CNTs/metal nanocomposite powder for selective laser melting (SLM) due to the agglomeration of the CNTs. This work focused on the preparation of multi-walled carbon nanotubes/Ti6Al4V (MWCNTs/TC4) nanocomposite powder for laser AM by a planetary ball-milling (PBM). The effect of ball-milling time on the characteristics of nanocomposite powder was studied and the underlying physical mechanism for powder preparation was disclosed. Three nanocomposite powders with milling time of 2 h, 4 h and 16 h were used for SLM processing to determine the optimal nanocomposite powders. The results showed that although the MWCNTs were dispersed uniformly in the matrix powder at increased milling time, severely plastic deformation of nanocomposite powder occurred with loss of its spherical shape. It was concluded that a ball-milling time of 4 h at a speed of 300 rpm was determined to achieve optimal nanocomposite powder for SLM. SLM processing of the nanocomposite powder demonstrated a smooth laser-powder interaction, yielding good metallurgical bonding of scanning tracks with previous tracks and relatively flat surface of samples. This work provided the significant reference to prepare high quality CNTs/metal nanocomposite powder for SLM, which has great potentials to fabricate high-performance metal matrix nanocomposite.
关键词： Planetary ball milling,Selective laser melting,Ti6Al4V (TC4) powder,Multi-walled carbon nanotubes (MWCNTs),Powder characteristics
更新于2025-09-23 15:19:57
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Multi-Walled Carbon Nanotubes/BiPO <sub/>4</sub> /BiOI Heterostructure Composite Photoelectrochemical Sensor in Detection of Salicylic Acid
摘要： In this work, BiOI, BiPO4, BiPO4/BiOI (M) and MWCNT/BiPO4/BiOI(MWCNT/M) heterostructure were synthesized through hydrothermal methods and served the function of fabricating photoelectrochemical (PEC) sensor for detection of Salicylic acid (SA). MWCNT covered with BiPO4/BiOI were observed with the aid of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Under visible light excitation, the low detection limit of 0.55 μM and working range of 1–320 μM and 480–3840 μM were obtained at the MWCNT/M/ITO. Moreover, it has excellent reproducibility and long-term stability. Meanwhile, results suggest that MWCNT/M developed herein offers a promising platform for the ultrasensitive detection of SA.
关键词： Multi-Walled Carbon Nanotubes,BiPO4/BiOI Heterostructure,Photoelectrochemical Sensor,Salicylic Acid
更新于2025-09-23 15:19:57
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Raman Spectroscopy as an Assay to Disentangle Zinc Oxide Carbon Nanotube Composites for Optimized Uric Acid Detection
摘要： Refluxed zinc oxide (ZnO) nanoparticles (NPs) were prepared and attached to carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWNTs) via sonication. Practical optimization of electrocatalysts using sonication to disentangle a carbon nanotube composite for monitoring uric acid (UA) is shown. Monitoring UA is important for the management of medical disorders. Selection of sonication time is a crucial step in producing the desired composite. We report, for the first time, the practical use of Raman spectroscopy to tune the sonication involved in tethering ZnO NPs to the multi-walled carbon nanotube (MWNT) surface. Maximum current for detecting UA, using chronoamperometry and cyclic voltammetry, correlated with the highest sp2-hybridized carbon signal, as seen in the integrated Raman G band peak areas denoting maximum COOH-MWNT disentanglement. An array of ZnO/COOH-MWNT composites were prepared ranging from 60 to 240 min sonication times. Optimum sonication (150 min) corresponded with both maximum measured current and MWNT disentanglement. The sensor was able to quantitatively and selectively measure UA at clinically relevant concentrations (100–900 μM) with rapid current response time (< 5 s).
关键词： chronoamperometry,zinc oxide nanoparticles,Raman spectroscopy,cyclic voltammetry,multi-walled carbon nanotubes,electrochemical sensing
更新于2025-09-19 17:15:36
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Role of Carbon Nanotubes to Enhance the Long-Term Stability of Dye-Sensitized Solar Cells
摘要： Improving the long-term stability of Dye-sensitized solar cells (DSSCs) is a critical challenge which affects both their technical viability and future large-scale commercialization. Here, we investigate the role of multi-wall carbon nanotubes (MWCNTs) in improving the long-term stability of DSSCs by comparing the performance of two series of devices made of (i) bare nanocrystalline TiO2 and (ii) MWCNTs-TiO2 composite anode, exposed to continuous simulated sunlight, indoor and ultraviolet (UV) light irradiation. The DSSCs based on the composite anode showed approximately three times longer stability compared to the standard device. To understand the degradation mechanisms that underpin these changes in device performance, both devices were characterized using various techniques. The results indicate that the MWCNTs can act as a conductive support, reinforcing the TiO2 nanoparticles matrix and offering a directional path to the photo-injected electrons, which enhances electron lifetime and reduces the carrier recombination rate. UV stability measurements demonstrated that MWCNTs can partially absorb and act as a blocking agent for UV light, thereby preventing degradation. The Raman spectra showed that dye desorption was decreased by the addition of MWCNTs. Our results provide a fundamental understanding of photoanode degradation mechanisms under illumination and offer a simple, low-cost and large-area scalable approach to fabricate long-term stable solar energy conversion devices.
关键词： Multi-walled carbon nanotubes,Long-term stability,Dye-sensitized solar cells,hybrid composite,degradation mechanism
更新于2025-09-19 17:13:59
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Vertically aligned laser sliced MWCNTs
摘要： Applications of multi-walled carbon nanotubes (MWCNTs) benefit from the availability of specific lengths of the material while keeping the outer walls pristine, for example, for applications requiring vertically aligned tubes. To this end, a simple and effective continuous flow ‘top down’ process to control the length of sliced MWCNTs has been developed using a vortex fluidic device (VFD) coupled with a 1064 nm pulse laser, with the process in the absence of chemicals and any auxiliary substances. Three different length distributions of the sliced MWCNTs, centered at 75 ± 2.1 nm, 300 ± 1.8 nm and 550 ± 1.4 nm, have been generated with the length depending on the VFD operating parameters and laser energy, with the processing resulting in a decrease in side wall defects of the material. We also show the ability to vertically self assemble short MWCNTs on a silicon substrate with control of the surface density coverage using a simple dipping and rinsing method.
关键词： multi-walled carbon nanotubes,vortex fluidic device,nanotechnology,vertical alignment,laser slicing
更新于2025-09-16 10:30:52
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Field emission property of vertically aligned nitrogen-doped multi-walled carbon nanotubes produced by chemical vapor deposition
摘要： Vertically aligned nitrogen-doped multi-walled carbon nanotubes (N-MWNTs) were synthesized by the chemical vapor deposition (CVD) at 900 °C using imidazole mixed with ferrocene as carbon and nitrogen sources, and catalyst, respectively. The effects of ammonia (NH3) and hydrogen (H2) flow rates on the growth of N-MWNTs were investigated (hereafter referred to A-N-MWNTs and H-N-MWNTs, respectively). Transmission electron microscopy (TEM) revealed the bamboo-like structure of the N-MWNTs, in which the separation between individual bamboo compartments decreased with increasing nitrogen concentration in N-MWNTs. X-ray photoelectron spectroscopy (XPS) analysis results supported that the nitrogen concentrations in N-MWNTs is 0.55 at.%, whereas A-N-MWNTs and H-N-MWNTs with the flow rate at 10 standard cubic centimeters per minute (sccm) (10A-N-MWNTs and 10H-N-MWNTs, respectively) showed 1.14 and 4.06 at.%, respectively. We found that the optimal conditions for the highest nitrogen-doped multi-walled carbon nanotubes (MWNTs) was a flow rate of NH3 and H2 at 10 sccm. Results from field emission measurements indicated that the turn-on fields of N-MWNTs, 10A-N-MWNTs and 10H-N-MWNTs were 6.7, 4.3 and 3.1 V/μm, respectively, while the field enhancement factors (β) were 5230, 10,805 and 20,390, respectively. Furthermore, the current density of N-MNWTs increased with increasing the nitrogen atoms in MWNTs. The results support that field emission based on N-MWNTs is a good emitter with low turn-on field and large field enhancement factor. Nitrogen doping in MWNTs makes them attractive candidates as high-performance field emitters.
关键词： Field emission,Nitrogen-doped multi-walled carbon nanotubes,Chemical vapor deposition
更新于2025-09-12 10:27:22
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Facile preparation and properties of polyvinylidene fluoride dielectric nanocomposites <i>via</i> phase morphology control and incorporation of multiwalled carbon nanotubes conductive fillers
摘要： A novel PVDF dielectric nanocomposite was achieved by controlling phase morphology and incorporating conductive ?llers simultaneously, and the mechanical, thermal, dielectric properties of the resultant dielectric nanocomposites were investigated. Mechanical analysis showed that incorporation of modi?ed MWCNTs (MWCNTs-COOH) in the PVDF nanocomposites resulted in signi?cant improvements on the tensile strength (Ts) and elasticity modulus (Em). When the ?ller content was 12 wt%, the Ts of MWCNTs-COOH/PVDF could reach 64.6 MPa. XRD test showed that the addition of MWCNTs-COOH and MWCNTs promoted the formation of β-phase of PVDF. DMA analysis showed that the glass-transition temperature of the PVDF nanocomposites slightly increases on loading of original MWCNTs and this effect was more pronounced on loading MWCNTs-COOH. The dielectric property analysis showed that the original MWCNTs were more likely to form local conductive networks in the PVDF matrix, promoting the electron displacement polarization, and improving the dielectric constant. When the contents of MWCNTs was 12 wt%, the percolation threshold was obtained and the dielectric constant (ε0) reached 286, which was 36 times of pure PVDF. Our work provides a simple way to fabricate polymer blends with excellent dielectric performances, good mechanical properties as well as good processing capability but low cost.
关键词： polyvinylidene ?uoride (PVDF),thermal performance,dielectric properties,multi-walled carbon nanotubes (MWCNTs),mechanical properties
更新于2025-09-11 14:15:04