Search Results (13)

Carbon nanotubes (CNTs) are often regarded as semi-rigid, all-carbon polymers. However, unlike conventional polymers that can form 3D networks such as hydrogels or elastomers through crosslinking in solution, CNTs have long been considered non-crosslinkable under mild conditions. This perception changed with our recent discovery of UV-defluorination-driven direct crosslinking of CNTs in solution. In this study, we further investigate the thermal stability of UV-defluorination-driven crosslinked CNTs, revealing that they are metastable and decompose more readily than either pristine or fluorinated CNTs under Raman laser irradiation. Using Raman spectroscopy under controlled laser power, we examined both single-walled and multi-walled fluorinated CNTs. The results demonstrate that UV-defluorinated CNTs exhibit reduced thermal stability compared to their pristine or untreated fluorinated counterparts. This instability is attributed to the strain on the intertube crosslinking bonds resulting from the curved carbon lattice of the linked CNTs. The metallic CNTs in the crosslinked CNT networks decompose and revert to their pristine state more readily than the semiconducting ones. The inherent instability of crosslinked CNTs leads to combustion at temperatures approximately 100 °C lower than those required for non-crosslinked fluorinated CNTs. This property positions crosslinked CNTs as promising candidates for applications where mechanically robust, lightweight materials are needed, along with feasible post-use removal options. Full article

Water may easily become polluted by pharmaceutical wastes, such as phenazopyridine hydrochloride. The pollutant can be removed by electrochemical oxidation in the form of minerals. A novel electrode has been developed for this purpose. Pt nanoparticles (PtNPs) are electrodeposited onto multiwalled carbon nanotubes supported onto fluorine-doped tin oxide (FTO/Glass). The resulting PtNP@MWCNT-FTO-E electrode is characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, electron diffraction spectroscopy and X-ray photoelectron spectroscopy. The electrode exhibits high efficiency in the electrochemical oxidation process thanks to the large specific surface area of the PtNPs and their ability to behave as charge transfer catalysts. The contaminant undergoes complete mineralization, leaving no organics after treatment. The resulting nitrate ions further confirm contaminant mineralization, but fortunately, they disappear over time, which confirms the safety of the process in water treatment. Moreover, the electrode operates under a variety of applied potentials, pH values, temperatures and contaminant concentrations. The electrode exhibits high stability upon recovery and reuse while retaining its physical characteristics before and after use. This study highlights the benefit of using Pt nanoparticles in the electro-degradation of aqueous organic contaminants, especially waste pharmaceuticals, for the first time. It also recommends scaling up the process and studying the continuous-flow reaction process to assess the economic and technical feasibility in future large-scale applications. Full article

The development of conducting polymer incorporated with carbon materials-based electrochemical biosensors has been intensively studied due to their excellent electrical, optical, thermal, physical and chemical properties. In this work, a label-free electrochemical dopamine (DA) biosensor based on polyaniline (PANI) and its aminated derivative, i.e., poly(3-aminobenzylamine) (PABA), composited with functionalized multi-walled carbon nanotubes (f-CNTs), was developed to utilize a conducting polymer as a transducing material. The electrospun nanofibers of the composites were fabricated on the surface of fluorine-doped tin oxide (FTO)-coated glass substrate under the optimized condition. The PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers were characterized by attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which confirmed the existence of f-CNTs in the composites. The electroactivity of the electrospun nanofibers was investigated in phosphate buffer saline solution using cyclic voltammetry (CV) before being employed for label-free electrochemical detection of DA using differential pulse voltammetry (DPV). The sensing performances including sensitivity, selectivity, stability, repeatability and reproducibility of the fabricated electrospun nanofiber films were also electrochemically evaluated. The electrochemical DA biosensor based on PANI/f-CNTs and PABA/f-CNTs electrospun nanofibers exhibited a sensitivity of 6.88 µA·cm⁻²·µM⁻¹ and 7.27 µA·cm⁻²·µM⁻¹ in the linear range of 50–500 nM (R² = 0.98) with a limit of detection (LOD) of 0.0974 µM and 0.1554 µM, respectively. The obtained DA biosensor showed great stability, repeatability and reproducibility with precious selectivity under the common interferences, i.e., glucose, ascorbic acid and uric acid. Moreover, the developed electrochemical DA biosensor also showed the good reliability under detection of DA in artificial urine. Full article

Environmental pollution can be caused by the improper disposal of agricultural waste and the use of fluorinated chemicals. Icing is a natural phenomenon, but the accumulation of ice on the surface of electrical equipment can damage the equipment and reduce power generation efficiency. Preparation of biochar anti-icing coatings with a fluorine-free process promotes resource utilization and environmental protection. In this study, superhydrophobic coatings with photothermal effect prepared based on biochar as a filler, which was blended with multi-walled carbon nanotubes (MWCNTs) and polyurea adhesive. The coating exhibits remarkable durability, as well as anti-icing, antifrosting, and self-cleaning characteristics. Utilizing fluorine-free chemicals enhances the environmentally friendly nature of the coating. The coating exhibits a contact angle of 155°, and the temperature can increase to 47.6 °C within a duration of 10 min. It can complete ice detachment in 128 s and defrosting in 210 s. The coating demonstrated exceptional durability when exposed to mechanical abrasion using sandpaper and steel brushes, water jet impact, acid and alkali corrosion, and tape-peeling tests. This study streamlines the procedure for creating photothermal superhydrophobic coatings, which contributes to environmental conservation and sustainable development. Additionally, it broadens the possibilities for recycling and reusing rejected crops. Full article

Sub-fluorinated carbon nanofibers (F-CNFs) can be described as a non-fluorinated core surrounded by a fluorocarbon lattice. The core ensures the electron flux in the cathode during the electrochemical discharge in the primary lithium battery, which allows a high-power density to be reached. The ball-milling in an inert gas (Ar) of these F-CNFs adds a second level of conductive sp² carbons, i.e., a dual sub-fluorination. The opening of the structure changes, from one initially similar multi-walled carbon nanotube to small lamellar nanoparticles after milling. The power densities are improved by the dual sub-fluorination, with values of 9693 W/kg (3192 W/kg for the starting material). Moreover, the over-potential of low depth of discharge, which is typical of covalent CFx, is suppressed thanks to the ball-milling. The energy density is still high during the ball-milling, i.e., 2011 and 2006 Wh/kg for raw and milled F-CNF, respectively. Full article

Fluorinated multi-walled carbon nanotubes are implemented as the third component of the active layer of organic solar cells. The addition of approximately 1% weight fraction of these nanotubes into PCDTBT/PC₆₀BM polymer/fullerene active layer leads to a noticeable increase in the main photovoltaic parameters of the solar cells, including their stability. Presumably, the origins of this influence are optimizing the donor/acceptor composite morphology and reinforcing its structure with fluorinated multi-walled carbon nanotubes. This hypothesis is supported by the dramatic influence of the fluorinated multi-walled carbon nanotube additive on the kinetics of the decay of the EPR signal of light-induced charges in the PCDTBT/PC₆₀BM composite. Full article

In this study, multi-walled carbon nanotubes (MWCNTs) were modified by thermal fluorination to improve dispersibility between MWCNTs and Li₄Ti₅O₁₂ (LTO) and were used as additives to compensate for the disadvantages of LTO anode materials with low electronic conductivity. The degree of fluorination of the MWCNTs was controlled by modifying the reaction time at constant fluorination temperature; the clear structure and surface functional group changes in the MWCNTs due to the degree of fluorination were determined. In addition, the homogeneous dispersion in the LTO was improved due to the strong electronegativity of fluorine. The F-MWCNT conductive additive was shown to exhibit an excellent electrochemical performance as an anode for lithium ion batteries (LIBs). In particular, the optimized LTO with added fluorinated MWCNTs not only exhibited a high specific capacity of 104.8 mAh g⁻¹ at 15.0 C but also maintained a capacity of ~116.8 mAh g⁻¹ at a high rate of 10.0 C, showing a capacity almost 1.4 times higher than that of LTO with the addition of pristine MWCNTs and an improvement in the electrical conductivity. These results can be ascribed to the fact that the semi-ionic C–F bond of the fluorinated MWCNTs reacts with the Li metal during the charge/discharge process to form LiF, and the fluorinated MWCNTs are converted into MWCNTs to increase the conductivity due to the bridge effect of the conductive additive, carbon black, with LTO. Full article

Li-S batteries still suffer from two of the major challenges: polysulfide shuttle and low inherent conductivity of sulfur. Here, we report a facile way to develop a bifunctional separator coated with fluorinated multiwalled carbon nanotubes. Mild fluorination does not affect the inherent graphitic structure of carbon nanotubes as shown by transmission electron microscopy. Fluorinated carbon nanotubes show an improved capacity retention by trapping/repelling lithium polysulfides at the cathode, while simultaneously acting as the “second current collector”. Moreover, reduced charge-transfer resistance and enhanced electrochemical performance at the cathode-separator interface result in a high gravimetric capacity of around 670 mAh g⁻¹ at 4C. Unique chemical interactions between fluorine and carbon at the separator and the polysulfides, studied using DFT calculations, establish a new direction of utilizing highly electronegative fluorine moieties and absorption-based porous carbons for mitigation of polysulfide shuttle in Li-S batteries. Full article

A global freshwater pollution catastrophe is looming due to pollutants of emerging concern (PECs). Conventional water treatment methods are limited in removing PECs such as pharmaceuticals and dye house effluent from aquatic systems. This study provides an effective potential solution by developing an innovative wastewater treatment method based on solar-light-responsive semiconductor-based photocatalysts. A sol-gel synthesis technique was used to produce Fluorine-Sm³⁺ co-doped TiO₂ (0.6% Sm³⁺) (FST3) photocatalysts. This was followed by loading multi-walled carbon nanotubes (MWCNTs) in the range of 0.25 to 1 wt% into the FST3 matrix. Solid state UV-visible spectroscopy measurements showed a bathochromic shift into the visible light region after the co-doping of TiO₂, whereas XRD analysis confirmed the presence of predominantly anatase polymorphs of TiO₂. The FT-IR and EDX results confirmed the presence of the F and Sm³⁺ dopants in the synthesised photocatalysts. XRD and TEM measurements confirmed that the crystallite sizes of all synthesised photocatalysts ranged from 12–19 nm. The resultant photocatalysts were evaluated for photocatalytic degradation of Brilliant Black BN bis-azo dye in aqueous solution under simulated solar irradiation. FST3 completely degraded the dye after 3 h, with a high apparent rate constant (K_a) value (2.73 × 10⁻² min⁻¹). The degree of mineralisation was evaluated using the total organic carbon (TOC) technique, which revealed high TOC removal (82%) after 3 h and complete TOC removal after 4 h. The incorporation of F improved the optical properties and the surface chemistry of TiO₂, whereas Sm³⁺ improved the quantum efficiency and the optical properties. These synergistic effects led to significantly improved photocatalytic efficiency. Furthermore, incorporating MWCNTs into the F and Sm³⁺ co-doped TiO₂ (0.6% Sm³⁺) improved the reaction kinetics of the FST3, effectively reducing the reaction time by over 30%. Recyclability studies showed that after 5 cycles of use, the FST3/C1 degradation efficiency dropped by 7.1%, whereas TiO₂ degradation efficiency dropped by 33.4% after the same number of cycles. Overall, this work demonstrates a sustainable and efficient dye-removal technique. Full article

Composite electrospun fibers were fabricated to develop drug loaded scaffolds to promote bone tissue regeneration. Multi-wall carbon nanotubes (MWCNTs) were incorporated to polylactic acid (PLA) to strengthen electrospun nanofibers. To modulate drug release behavior, different ratios of hydrophilic polyethylene glycol (PEG) were added to composite fibers. Glass transition temperature (Tg) can be reduced by the incorporated PEG to enhance the ductility of the nanofibers. The SEM images and the MTT results demonstrated that composite fibers are suitable scaffolds for cell adhesion and proliferation. Dexamethasone (DEX), an osteogenic inducer, was loaded to PLA/MWCNT/PEG fibers. The surface element analysis performed by XPS showed that fluorine of DEX in pristine PLA fibers was much higher than those of the MWCNT-containing fibers, suggesting that the pristine PLA fibers mainly load DEX on their surfaces, whereas MWCNTs can adsorb DEX with evenly distribution in nanofibers. Drug release experiments demonstrated that the release profiles of DEX were manipulated by the ratio of PEG, and that the more PEG in the nanofibers, the faster DEX was released. When rat bone marrow stromal cells (rBMSCs) were seeded on these nanofibers, the Alizarin Red S staining and calcium quantification results demonstrated that loaded DEX were released to promote osteogenic differentiation of rBMSCs and facilitate mineralized tissue formation. These results indicated that the DEX-loaded PLA/MWCNT/PEG nanofibers not only enhanced mechanical strength, but also promoted osteogenesis of stem cells via the continuous release of DEX. The nanofibers should be a potential scaffold for bone tissue engineering application. Full article

Transparent conductive films are fundamental materials, currently used in several fields. Recently, due to their unique multifunctional properties, composite materials have started to be used in place of fluorine tin oxide and indium tin oxide in transparent conductive electrodes. However, the production of composite materials is still complicated and involves toxic chemicals. Through a simple and environmentally-friendly method, we synthesized new composite materials—conductive, transparent, and flexible films—that can be applied to the production of modern optoelectronic devices. An even dispersion of the nanoparticles was achieved by ultrasound excitation. Moreover, a series of morphological and structural investigations were conducted on the films by scanning and transmission electron microscopy, electrical conductivity, Raman spectroscopy, X-ray diffraction and testing their sheet resistance. The results indicated that the tested composite materials were ideal for film coating. The nanofluids containing multi-walled carbon nanotubes presented the highest electrical conductivity; nevertheless, all the composite nanofluids tended to have relatively high electrical conductivities. The flexible films with composite structures presented lower sheet resistances than those with single structures. Finally, the hybrid materials showed a higher transmittance. Full article

Multiwalled carbon nanotubes (MWCNTs) have excellent electrical conductivity and good chemical stability, and are used as counter electrodes in dye-sensitized solar cells (DSSCs). The counter electrodes collect electrons from the external circuit and catalyze the redox reaction in the electrolyte. Electrocatalysis is an important step for generating energy from triiodide reduction in DSSCs. In this study, chemically treated MWCNTs were investigated for improving the photovoltaic performance of DSSCs. The MWCNTs were modified through chemical oxidation with sulfuric acid/nitric acid (H₂SO₄/HNO₃) or potassium persulfate/sodium hydroxide (K₂S₂O₈/NaOH). Nanocellulose (CNC) was used as a dispersant to improve the photovoltaic performance and dispersibility as an alternative material for counter electrodes in DSSCs. The counter electrodes were prepared on fluorine-doped tin oxide (FTO) glass substrates by spin coating nanofluids. Morphological and structural investigations were performed using scanning transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, and Raman spectroscopy. The electrical conductivity and UV light absorption of the DSSCs were analyzed to evaluate their photovoltaic performance. The results of these analyses showed that chemical functionalization and addition of CNC were effective for increasing the electrical conductivity and UV light absorption. Finally, all result trends were the same. Increasing the dispersibility of the counter electrode was found to improve the reduction of I₃⁻ at the interface between the MWCNTs and the electrolyte, thereby, improving the energy conversion efficiency. Full article

Bulk oriented films based on ultrahigh molecular weight polyethylene (UHMWPE) with a drawing ratio of 35 were prepared by using a low solvent concentration. Bulk oriented films were filled with fluorinated multi-walled carbon nanotubes (FMWCNTs). The structure of bulk oriented films on UHMWPE, which were manufactured at different stages of orientation, was investigated by scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The addition of FMWCNTs at a concentration of 0.05 wt % in bulk oriented UHMWPE films led to an increase in the tensile strength by 10% (up to 1020 ± 23 MPa) compared to unfilled oriented films. However, the addition of FMWCNTs at a concentration of more than 0.5 wt % led to a decrease in tensile strength due to excessive accumulation of nanotubes and hindering of self-diffusion of UHMWPE macromolecules. The multiple increase in tensile strength, doubling the hardness, the formation of fibrillar structure, and the presence of carbon nanotubes led to a significant increase in tribological properties in bulk oriented films. Bulk oriented UHMWPE/1% FMWCNT films can be operated at a maximum contact pressure that is 18 times higher and exhibit a specific wear rate more than an order of magnitude and less than the traditional UHMWPE of isotropic structure. Bulk oriented UHMWPE/1% FMWCNT films have an extremely low dry coefficient of friction (COF) of 0.075 at a contact pressure of 31 MPa. The developed bulk oriented films can be used for manufacturing frictional surfaces for sliding bearings, or for acetabular cups for knee and hip endoprostheses. Full article