Search Results (65)

Hydroxychloroquine (HCQ), a cornerstone therapeutic agent for autoimmune diseases, requires precise serum concentration monitoring due to its narrow therapeutic window. Current HCQ monitoring methods such as HPLC and LC-MS/MS are sensitive but costly and complex. While electrochemical sensors offer rapid, cost-effective detection, their large chambers and high sample consumption hinder point-of-care use. To address these challenges, we developed a microfluidic electrochemical sensing platform based on a screen-printed carbon electrode (SPCE) modified with a hierarchical nanocomposite of gold nanoparticles (AuNPs), copper-based metal–organic frameworks (Cu-MOFs), and multi-walled carbon nanotubes (MWCNTs). The Cu-MOF provided high porosity and analyte enrichment, MWCNTs established a 3D conductive network to enhance electron transfer, and AuNPs further optimized catalytic activity through localized plasmonic effects. Structural characterization (SEM, XRD, FT-IR) confirmed the successful integration of these components via π-π stacking and metal–carboxylate coordination. Electrochemical analyses (CV, EIS, DPV) revealed exceptional performance, with a wide linear range (0.05–50 μM), a low detection limit (19 nM, S/N = 3), and a rapid response time (<5 min). The sensor exhibited outstanding selectivity against common interferents, high reproducibility (RSD = 3.15%), and long-term stability (98% signal retention after 15 days). By integrating the nanocomposite-modified SPCE into a microfluidic chip, we achieved accurate HCQ detection in 50 μL of serum, with recovery rates of 95.0–103.0%, meeting FDA validation criteria. This portable platform combines the synergistic advantages of nanomaterials with microfluidic miniaturization, offering a robust and practical tool for real-time therapeutic drug monitoring in clinical settings. Full article

At present, the oil extraction and chemical industry and other industries produce a large amount of oily wastewater and organic sewage, and the world is suffering from oil spills and organic wastewater pollution. As a porous material, aerogels are promising in the field of oil adsorption. In this work, the nanocellulose/aminated multi-walled carbon nanotube (NC-MWCNT-NH₂) nanocomposite aerogel with a high porosity of up to 97.80% is prepared by varying the weight percentage of MWCNTs-NH₂, among which the nanocomposite aerogel with 0.1% weight percentage of MWCNTs-NH₂ exhibits the best adsorption performance with the adsorption capacity to cyclohexane, ethyl acetate, anhydrous ethanol, methylene dichloride, acetone, kerosene, pump oil, and used pump oil of 39.77 ± 0.82, 44.54 ± 1.67, 43.03 ± 1.06, 62.13 ± 0.36, 39.92 ± 1.09, 39.37 ± 0.27, 43.48 ± 0.06, and 38.45 ± 0.84 g·g⁻¹, respectively. Compared with pure nanocellulose aerogel, the adsorption capacity of the NC-MWCNT-NH₂ aerogel to pump oil is improved by up to 93.9%, which exhibits excellent adsorption properties and could be utilized in the field of oil adsorption. Full article

This paper discusses the results of our investigation of the effect of processing parameters on the electrochemical properties of poly(vinylidene fluoride) single-walled carbon nanotube sheets and PVDF-CNTs modified by solution cast polyimide coating, followed by electrodeposition of polypyrrole. The polyimide-coated single-wall carbon nanotube sheet–PI/SWCNTs composite consists of SWCNT and PVDF (9:1) wt.% and 0.1–1 wt.% polyimide. The processing temperature varied from 90 to 250 °C. SEM images validated the nanostructure, while EDX confirmed the material composition. EIS analysis showed that the composite electrode material processed at 90 °C and followed by electrodeposition of polypyrrole has the lowest bulk resistance (65.27 Ω), higher porosity (4.59%), and the highest specific capacitance (209.16 F/g), indicating superior ion transport and charge storage. Cyclic voltammetry and cyclic charge–discharge analyses revealed that the hybrid composite electrode processed at 90 °C achieved a specific capacitance of 655.34 F/g at a scan rate of 5 mV/s, demonstrating excellent cycling stability over 10 cycles at a current density of 0.5 A/g. In contrast, composite electrodes processed at 180 °C and 250 °C showed decreased performance due in part to structural densification and low porosity. These findings underscore the critical role of processing temperatures in optimizing the electrochemical properties of PI/SWCNT composites, advancing their potential for next-generation energy storage systems. Full article

The conversion of biochar, the low value byproduct of pyrolysis bio-oil production from biomass multi-walled carbon nanotubes (MWCNTs) and carbon nanochains (CNCs), is reported. It is shown that biomass can be converted to long (>30 µm) carbon nanotubes with an anomalously deep (>280 nm) stacked-cup structure. A mechanism of the transformation that is consistent with previously reported graphitization of biochar, a “non-graphitizable” carbon, is proposed, suggesting the molten metal catalyst is absorbed into the biochar by capillary action, forming graphene walls as it percolates through pore structure. Graphite is formed when the diameter of the molten catalyst droplets is large (microns), while smaller droplets (submicron) form MWCNTs and still smaller (<100 nm) form CNCs. Branching in the biochar pore structure leads to subdivision of the catalyst droplets resulting in the progression from MWCNT to CNC formation. Very long MWCNTs (>50 µm) can be formed in the absence of CNCs by transforming lignite char rather than biochar, presumably due to the elimination of smaller branching pores during coalification. CNCs, in the absence of MWCNTs, can be formed in biochar by using low concentrations of catalyst nanoparticles formed by carbon thermal reduction of a metal salt during charring. The results presented suggest that developing methods to control the porosity of the char could yield the ability to rationally synthesize carbon nanotubes with control of length, breadth and wall thickness. Full article

In this study, we research the innovative application of multi-walled carbon nanotubes (MWCNTs) as corrosion inhibitors in Portland cement embedded steel. The physicochemical properties of the dispersion solutions were evaluated, varying the storage time, to analyze their effect on corrosion resistance. Using a dispersion energy of 440 J/g and a constant molarity of 10 mM, stable dispersions were achieved for up to 3 weeks. These dispersions were characterized using Raman spectroscopy, UV-Vis spectroscopy and Zeta potential spectroscopy to assess the stability and structural damage of the MWCNTs. These results show that the addition of MWCNTs not only reduces the porosity of the cement matrix, but also forms an effective barrier against chloride ion intrusion, protecting the reinforcing steel. This approach stands out for combining improved mechanical properties and significant corrosion resistance, representing a promising innovation in the development of more durable construction materials. Full article

Developing materials for efficient energy storage and effective electromagnetic interference (EMI) shielding is crucial in modern technology. This study explores the synthesis and characterization of carbonaceous shape-stabilized octadecane/MWCNT (multi-walled carbon nanotube) composites, utilizing activated carbon, expanded graphite or ceramic carbon foam, as shape stabilizers for phase change materials (PCMs) to enhance thermal energy storage and EMI shielding, for energy-efficient and advanced applications. The integration of octadecane, a phase change material (PCM) with carbonaceous stabilizers ensures the material’s stability during phase transitions, while MWCNTs contribute to improved thermal storage properties and EMI shielding capabilities. The research aims to develop novel composites with dual functionality for thermal storage and EMI shielding, emphasizing the role of carbon matrices and their MWCNT composites. SEM and CT microtomography analyses reveal variations in MWCNT incorporation across the matrices, influenced by surface properties and porosity. Leaching tests, infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) confirm the composite’s stability and high latent heat storage. The presence of nanotubes enhances the thermal properties of octadecane and ΔH values almost reached their theoretical values. EMI shielding effectiveness measurements indicate that the composites show improved electric properties in the presence of MWCNTs. Full article

Lithium–sulfur (Li–S) batteries are expected to be one of the next generations of high-energy-density battery systems due to their high theoretical energy density of 2600 Wh kg⁻¹. Embracing the trends toward flexibility, lightweight design, and cost-effectiveness, paper-based electrodes offer a promising alternative to traditional coated cathodes in Li–S batteries. Within paper-based electrodes, conductive fibers such as carbon nanotubes (CNTs) play a crucial role. They help to form a three-dimensional network within the paper matrix to ensure structural integrity over extended cycling while mitigating the shuttle effect by confining sulfur within the cathode. Herein, we explore how variously functionalized CNTs, serving as conductive fibers, impact the physical and electrochemical characteristics of paper-based sulfur cathodes in Li–S batteries. Specifically, graphitized hydroxylated carbon nanotubes (G-CNTs) exhibit remarkable capacity at low currents owing to their excellent conductivity and interaction with lithium polysulfide (LiPS), achieving the highest initial specific capacity of 1033 mAh g⁻¹ at 0.25 C (1.1 mA cm⁻²). Aminated multi-walled carbon nanotubes (NH₂-CNTs) demonstrate an enhanced affinity for LiPS due to the -NH₂ groups. However, the uneven distribution of these fibers may induce electrode surface passivation during charge–discharge cycles. Notably, hydroxylated multi-walled carbon nanotubes (OH-CNTs) can establish a uniform and stable 3D network with plant fibers, showcasing superior mechanical properties and helping to mitigate Li₂S agglomeration while preserving the electrode porosity. The paper-based electrode integrated with OH-CNTs even retains a specific capacity of approximately 800 mAh g⁻¹ at about 1.25 C (5 mA cm⁻²), demonstrating good sulfur utilization and rate capacity compared to other CNT variants. Full article

A combined computational and experimental study of 3D-printed scaffolds made from hybrid nanocomposite materials for potential applications in bone tissue engineering is presented. Polycaprolactone (PCL) and polylactic acid (PLA), enhanced with chitosan (CS) and multiwalled carbon nanotubes (MWCNTs), were investigated in respect of their mechanical characteristics and responses in fluidic environments. A novel scaffold geometry was designed, considering the requirements of cellular proliferation and mechanical properties. Specimens with the same dimensions and porosity of 45% were studied to fully describe and understand the yielding behavior. Mechanical testing indicated higher apparent moduli in the PLA-based scaffolds, while compressive strength decreased with CS/MWCNTs reinforcement due to nanoscale challenges in 3D printing. Mechanical modeling revealed lower stresses in the PLA scaffolds, attributed to the molecular mass of the filler. Despite modeling challenges, adjustments improved simulation accuracy, aligning well with experimental values. Material and reinforcement choices significantly influenced responses to mechanical loads, emphasizing optimal structural robustness. Computational fluid dynamics emphasized the significance of scaffold permeability and wall shear stress in influencing bone tissue growth. For an inlet velocity of 0.1 mm/s, the permeability value was estimated at 4.41 × 10⁻⁹ m², which is in the acceptable range close to human natural bone permeability. The average wall shear stress (WSS) value that indicates the mechanical stimuli produced by cells was calculated to be 2.48 mPa, which is within the range of the reported literature values for promoting a higher proliferation rate and improving osteogenic differentiation. Overall, a holistic approach was utilized to achieve a delicate balance between structural robustness and optimal fluidic conditions, in order to enhance the overall performance of scaffolds in tissue engineering applications. Full article

Graphene aerogels are of high interest nowadays since they have ultralow density, rich porosity, high deformability, and good adsorption. In the present work, three different morphologies of graphene aerogels with a honeycomb-like structure are considered. The strength and deformation behavior of these graphene honeycomb structures are studied by molecular dynamics simulation. The effect of structural morphology on the stability of graphene aerogel is discussed. It is shown that structural changes significantly depend on the structural morphology and the loading direction. The deformation of the re-entrant honeycomb is similar to the deformation of a conventional honeycomb due to the opening of the honeycomb cells. At the first deformation stage, no stress increase is observed due to the structural transformation. Further, stress concentration on the junctions of the honeycomb structure and over the walls occurs. The addition of carbon nanotubes and graphene flakes into the cells of graphene aerogel does not result in a strength increase. The mechanisms of weakening are analyzed in detail. The obtained results further contribute to the understanding of the microscopic deformation mechanisms of graphene aerogels and their design for various applications. Full article

Electrochemical anodization is already a well-established process, owing to its multiple benefits for creating high-grade titanium dioxide nanotubes with suitable characteristics and tunable shapes. Nevertheless, more research is necessary to fully comprehend the basic phenomena at the anode-electrolyte interface during anodization. In a recent paper, we proposed the use of sawtooth-shaped voltage pulses for Ti anodization, which controls the pivoting point of the balance between the two processes that compete to create nanotubes during a self-organization process: oxide etching and oxidation. Under these conditions, pulsed anodization clearly reveals the history of nanotube growth as recorded in the nanotube morphology. We show that by selecting the suitable electrolyte and electrical discharge settings, a nanoporous structure may be generated as a repeating pattern along the nanotube wall axis. We report the findings in terms of nanotube morphology, crystallinity, surface chemistry, photocatalytic activity, and surface hydrophilicity as they relate to the electrical parameters of electrochemical anodization. Aside from their fundamental relevance, our findings could lead to the development of a novel form of TiO₂ nanotube array layer. Full article

With the development of nanotechnology, nanomaterials have been introduced to improve the engineering properties of cement-based building materials. An abundant number of studies have been carried out on normal-weight concrete using multi-walled carbon nanotubes (MWCNTs) or nano-silica (NS) and have proven their effectiveness. Nevertheless, still very few investigations are available in terms of lightweight cement-based materials, especially when MWCNTs and NS are binarily incorporated. Thus, in this study, fly ash cenospheres (FACs) according to cement weight were applied as lightweight fine aggregates to produce lightweight mortar (LWM). MWCNTs at 0.05, 0.15, and 0.45% and NS at 0.2 and 1.0% were binarily added as modifiers. Compressive and flexural strengths were tested to investigate mechanical behaviors. A water absorption test was conducted, together with scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP), to identify the impacts of the nano-additives on the pore structure of LWM. The following results were obtained: MWCNTs and NS demonstrated synergic effects on enhancing the mechanical properties of LWM. MWCNTs exerted positive impacts on reducing the porosity and improving the pore distribution at low dosages of 0.05 and 0.15%. The hybrid addition of NS further transformed large voids into small ones and introduced closed pores. Full article

Energy storage materials are constantly being improved and developed to cope with the ever-increasing demand of the electronic devices industry. Various synthetic approaches have been used to manufacture electrode materials. This paper is focused on the use of intrinsically conductive polymers such as polypyrrole (PPy) in the development of single-walled carbon nanotube-polyimide, SWCNT-PI, supercapacitor electrode materials. The polypyrrole used in the study is doped with different organic acid dopants of various sizes, including styrene sulfonic acid, SSA, toluene sulfonic acid, TSA, dodecylbenzene sulfonic acid, DBSA, naphthalene disulfonic acid, NDSA, and naphthalene trisulfonic acid, NTSA. The number of sulfonic acid functional group per dopant molecule varied from one to three, while the number of benzene rings in the aromatic unit varied from one to two. It is believed that, as the sulfonic acid to the dopant molecule ratio changes, the morphology and electrochemical properties of the doped PPy-coated electrode material will change accordingly. The change in the morphology of the doped PPy, due to the respective dopant, is correlated with the change in the electrochemical properties of the modified composite electrode. The naphthalene trisulfonic acid (NTSA) dopant was found to produce the highest specific capacitance of about 119 F/g at 5 mV/s. Furthermore, the NTSA-doped PPy electrode system showed the highest porosity and highest tan delta damping peak height for the a-transition. The styrene sulfonic acid-doped PPy/SWCNT-PI electrode material showed an impressive storage modulus of more than 2 GPa, but lower porosity. Styrene polymerization is believed to have occurred. The results obtained indicate that the porosity and electrochemical properties of the electrode materials are correlated. Full article

The use of electromagnetic interference shielding materials in the mitigation of electromagnetic pollution requires a broader perspective, encompassing not only the enhancement of the overall shielding efficiency (SE_T), but also the distinct emphasis on the contribution of the absorption shielding efficiency within the total shielding efficiency (SE_A/SE_T). The development of lightweight, biodegradable electromagnetic interference shielding materials with dominant absorption mechanisms is of paramount importance in reducing electromagnetic pollution and the environmental impact. This study presents a successful fabrication strategy for a poly(lactic acid)/polycaprolactone/multi-walled carbon nanotube (PCL/PLA/MWCNT) composite foam, featuring a uniform porous structure. In this approach, melt mixing is combined with particle leaching techniques to create a co-continuous phase morphology when PCL and PLA are present in equal mass ratios. The MWCNT is selectively dispersed within the PCL matrix, which facilitates the formation of a robust conductive network within this morphology. In addition, the addition of the MWCNT content reduces the size of the phase domain in the PCL/PLA/MWCNT composite, showing an adept ability to construct a compact and stable conductive network. Based on its porous architecture and continuous conductive network, the composite foam with an 80% porosity and 7 wt% MWCNT content manifests an exceptional EMI shielding performance. The SE_T, specific SE_T, and SE_A/SE_T values achieved are 22.88 dB, 88.68 dB·cm³/g, and 85.80%, respectively. Additionally, the resulting composite foams exhibit a certain resistance to compression-induced deformations. In summary, this study introduces a practical solution that facilitates the production of absorption-dominated, lightweight, and biodegradable EMI shielding materials at scale. Full article

Sulfate attack is one of the main factors affecting the durability of concrete structures. In recent years, multi-walled carbon nanotubes (MWCNTs) have attracted the attention of scholars for their excellent mechanical properties and durability performance. In this paper, the influence of sulfate attack and dry–wet cycles on the performance of multi-walled carbon nanotube–lithium slag concrete (MWCNT-LSC) with varied MWCNT content (0 wt.%, 0.05 wt.%, 0.10 wt.%, and 0.15 wt.%) and varied water–cement ratios (0.35, 0.40, and 0.45) were investigated. In addition, scanning electron microscopy (SEM) and X-ray computed tomography (CT) tests were conducted to analyze the microstructure and pore structure of the concrete. The results showed that concrete incorporated with MWCNTs could effectively mitigate sulfate attack. The resistance to sulfate attack of concrete was negatively related to the water–cement ratio when the dry–wet cycle was fixed. The MWCNT-LSC showed the best compressive strength at the water–cement ratio of 0.35 and 0.10 wt.% MWCNTs. The SEM test results showed that the MWCNTs filled the pores and cracks within the specimen and formed bridges between the cracks, enhancing the resistance to sulfate attack. The CT test results also showed that the addition of MWCNTs could reduce the porosity of concrete, refine the pore size and inhibit the generation and development of cracks, thus optimizing the internal structure of concrete and improving its resistance to sulfate attack. Full article

Recent growth in materials science and engineering technologies has pushed the construction industry to engage in new applications, such as the manufacturing of smart and electrically conductive products. Such novel uses of conductive construction materials would potentially allow their use in conjunction with various fields, such as those referred to as “Industry 4.0.” The following study uses iron oxide (Fe₃O₄)-multi-walled carbon nanotubes (MWCNTs) nanocomposites synthesized by chemical vapor deposition (CVD) and incorporated into the cementitious mortars as a substitute for sand at 1, 2, and 3% ratios to enhance the electrical conductivity. Results reveal that the electrical resistivity of cementitious composites decreases (due to the increase in electrical conductivity) from 208.3 to 61.6 Ω·m with both the Fe₃O₄-MWCNTs nanocomposites ratio and the increasing voltage. The lowest compressive strengths at 7 and 28 days are 12.6 and 17.4 MPa for specimens with 3% Fe₃O₄-MWCNTs and meet the standards that comply with most applications. On the other hand, the highest porosity was reached at 26.8% with a Fe₃O₄-MWCNTs rate of 3%. This increase in porosity caused a decrease in both the dry unit weight and ultrasonic pulse velocity (from 5156 to 4361 m/s). Further, it is found that the incorporation of Fe₃O₄-MWCNT nanocomposites can have a negative effect on the hardening process of mortars, leading to localized air cavities and an inhomogeneous development of cementing products. Nonetheless, the improvement of the electrical conductivity of the samples without significantly compromising their physico-mechanical properties will allow their use in various fields, such as deicing applications with low-voltage electric current. Full article