Search Results (741)

Recent advances in nanotechnology have highlighted the transformative potential of carbon-based nanomaterials, such as carbon nanofibers, carbon nanotubes, and graphene, in cementitious systems. These materials have shown a remarkable ability to enhance the mechanical strength, fracture toughness, and overall functional performance of cementitious composites. Their nanoscale dimensions and exceptional intrinsic properties allow for effective stress bridging, crack arrest, and matrix densification. Despite these promising features, the current understanding remains limited, particularly regarding their application to concrete. Furthermore, literature lacks systematic, parallel evaluations of their respective effectiveness in improving both mechanical performance and long-term durability, as well as their potential to impart true multifunctionality to concrete structures. It is worth noting that significant and statistically significant improvements in fracture behavior were observed at specific nanofiller concentrations, suggesting strong potential for the material system in next-generation innovative infrastructure applications. Experimental results demonstrated that both CNTs and GNPs significantly enhanced the mechanical performance of concrete, with flexural strength increases of approximately 49% and 38%, and compressive strength improvements of 22% and 47%, respectively, at optimum contents of 0.6 wt.% CNTs and 0.8 wt.% GNPs. SEM analyses confirmed improved matrix densification and interfacial bonding at these concentrations, while higher dosages led to agglomeration and reduced performance. This gap highlights the need for targeted experimental studies to elucidate the structure-property relationships governing these advanced materials. Full article

Exploring effective oxygen reduction reaction (ORR) electrocatalysts is essential for advancing solid-state alkaline zinc–air batteries (ZABs). This paper presents the synthesis of silver–manganese dioxide–carbon nanotubes (SMC) ternary composites as an electrocatalyst for air electrodes, achieved through one-step pyrolysis of silver permanganate under microwave irradiation. Characterization techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersion spectrometer (EDS) consistently confirmed the composition of SMC, comprising silver and alpha-manganese dioxide anchored on the surface of carbon nanotubes (CNTs). Electrochemical tests including polarization and chronoamperometry curves demonstrated the superior electrocatalytic activity of SMC for ORR compared to chemically produced electrocatalysts in alkaline conditions. Furthermore, the performance of a solid-state zinc–air cell with SMC as the electrocatalyst was evaluated, showing a long discharge voltage plateau and a capacity of 60.03 mAh at 30 mA·cm${}^{-2}$. The study also delves into the mechanism behind the enhanced electrocatalytic activity, concluding that the strategy and electrocatalyst developed in this research offer a promising approach for creating efficient oxygen reduction catalysts for solid-state zinc–air batteries. Full article

This review provides a comprehensive analysis of modern strategies for the synthesis, functionalization, and application of carbon nanotubes (CNTs) and graphene for the development of high-performance polymer composites in the field of strain sensing. The paper systematically organizes key synthesis methods for CNTs and graphene (chemical vapor deposition (CVD), such as arc discharge, laser ablation, microwave synthesis, and flame synthesis, as well as approaches to their chemical and physical modification aimed at enhancing dispersion within polymer matrices and strengthening interfacial adhesion. A detailed examination is presented on the structural features of the nanofillers, such as the CNT aspect ratio, graphene oxide modification, and the formation of hybrid 3D networks and processing techniques, which enable the targeted control of the nanocomposite’s electrical conductivity, mechanical strength, and flexibility. Central focus is placed on the fundamental mechanisms of the piezoresistive response, analyzing the role of percolation thresholds, quantum tunneling effects, and the reconfiguration of conductive networks under mechanical load. The review summarizes the latest advancements in flexible and stretchable sensors capable of detecting both micro- and macro-strains for structural health monitoring, highlighting the achieved improvements in sensitivity, operational range, and durability of the composites. Ultimately, this analysis clarifies the interrelationship between nanofiller structure (CNTs and graphene), processing conditions, and sensor functionality, highlighting key avenues for future innovation in smart materials and wearable devices. Full article

Carbon nanotube (CNT) and graphene-reinforced nanocomposites have become exceptional multifunctional materials because of their exceptional mechanical, thermal, and electrical properties. Recent developments in synthesis methods, dispersion strategies, and interfacial engineering have effectively overcome agglomeration-related limitations by significantly improving filler distribution, matrix compatibility, and load-transfer efficiency. These nanocomposites have better wear durability, corrosion resistance, and surface properties like super-hydrophobicity. A comparative analysis of polymer, metal, and ceramic matrices finds benefits for applications in biomedical, construction, energy, defense, and aeronautics. Functionally graded architecture, energy-harvesting nanogenerators, and additive manufacturing are some of the new fabrication processes that enhance design flexibility and functional integration. In recent years, scalability, life-cycle evaluation, and environmentally friendly processing have all gained increased attention. The development of next-generation, high-performance graphene and carbon nanotube (CNT)-based nanocomposites is critically reviewed in this work, along with significant obstacles and potential next steps. Full article

The incorporation of carbon nanostructures into polymer composites is of significant importance for the development of novel sensor materials, due to the excellent mechanical strength and variable electrical conductivity that these structures provide. It is evident that the significance of polylactide (PLA) and carbon nanotube (CNT) systems is attributable to two key factors. Firstly, these systems are notable for their environmental sustainability. Secondly, they exhibit enhanced functional properties. Despite the fact that a considerable number of studies have been conducted on conductive PLA/CNT composites, there has been limited research focusing on the supramolecular ordering of the polymer matrix and its impact on electromechanical properties. This factor, however, has been demonstrated in this study to significantly influence their response to applied stress and, consequently, their potential application as stress sensors. The present study has demonstrated that the precipitation method is an effective means of producing conductive PLA/MWNTs nanocomposites. This method is effective in ensuring the uniform dispersion of the filler in the polymer matrix, which creates an interesting prospect for mechanical sensors. It is evident that the durability of the nanocomposites is a key factor in ensuring the ordering of the supramolecular structure of the PLA matrix into the α form. The materials obtained were found to have a low percolation threshold of 0.2 wt.%. Furthermore, the practical application of these sensors, in the form of resistive strain sensors, was demonstrated for materials containing 5 wt.% of carbon nanotubes. The results presented here demonstrate that this methodology provides a novel perspective on the production of sensor materials, with the supramolecular ordering of the PLA matrix being a key factor. Full article

This study presents the development of high-performance polymer composites designed for operation under extreme conditions. The research aimed to investigate the influence of laser ablation parameters on the synthesis of carbon nanotubes (CNTs) and to evaluate their efficacy as electrically conductive fillers. CNTs were synthesized using a 200 W laser ablation setup, with the graphite-to-ferrocene ratio in the target varied from 3:1 to 8:1 at a constant pulse duration of 0.1 s. Comprehensive analysis by Raman spectroscopy and scanning electron microscopy (SEM) demonstrated that this method enables the production of nanotubes with controlled morphology and diameters ranging from 20 to 70 nm. It was established that varying the target composition serves as an effective tool for managing the specific surface area and structure of the synthesized CNTs. The obtained nanotubes exhibited high efficiency in forming conductive networks within polymer matrices (exemplified by silicone), thereby imparting the composites with tailored electrophysical properties. A key finding of the work is the identified dependence of the positive temperature coefficient of resistance (PTCR) of the composites on the morphology and composition of the carbon filler. This property opens prospects for creating “smart” self-regulating heating elements based on the developed materials, including for anti-icing systems. Thus, the study results confirm that the targeted synthesis of CNTs via laser ablation and their subsequent incorporation into polymer matrices constitutes an effective strategy for expanding the functional capabilities of composite materials in modern technical applications. Full article

The growing accumulation of plastic and electronic waste highlights the urgent need for sustainable and biodegradable polymers. However, developing intrinsically conductive biodegradable polymers remains challenging, particularly for packaging and sensing applications. Poly(lactic acid) (PLA) is intrinsically non-conductive, and enhancing its functionality without compromising structural integrity is a key research goal. In this study, PLA-based filaments were developed using melt extrusion, incorporating cellulose nanocrystals (CNCs), graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs), individually and in hybrid combinations with total filler contents between 1 and 5 wt%. The inclusion of CNC enhanced the dispersion of GNP and CNT, promoting the formation of interconnected conductive networks within the PLA matrix, allowing the percolation threshold to be reached at a lower fillers concentration. Hybrid formulations showed a balance melt strength and processability suitable for fused deposition modelling (FDM) 3D printing and prototypes successfully made. This study also provides the first systematic evaluation of temperature-dependent thermal conductivity of PLA-based composites at multiple temperatures (25, 5, and −20 °C), relevant to typical food and medical supply chains conditions. Full article

Infrared camouflage, realized by engineering temperature and spectral emission characteristics, is crucial in various scientific and engineering fields. Yet, a significant challenge lies in fabricating advanced functional materials that can durably maintain infrared camouflage performance under harsh operational conditions. Herein, we report a FeCl₃-intercalated carbon nanotube (CNT) film fabricated via a vapor intercalation strategy, with FeCl₃ molecules inserted into the interlayer spacing of the CNT. Compared with pristine CNT, the FeCl₃-intercalated CNT composite demonstrates significantly enhanced infrared camouflage capabilities, exhibiting apparent temperature variations of +16.7 °C, −6.6 °C, and −144 °C relative to the CNT film, under low (−4 °C), body (34.3 °C), and high (300 °C) temperature backgrounds, respectively. Moreover, extensive durability tests involving heat, insolation, and rain have confirmed the unaltered infrared camouflage performance of the FeCl₃-CNT film. The performance enhancement is attributed to the suppressed infrared absorptivity across the 2.5–15.2 μm wavelength range, with a pronounced reduction from 72% to 30% at 15 μm, driven by intercalation-induced charge transfer and the consequent Fermi energy (E_F) shift. This work presents a promising approach for designing advanced functional materials to achieve long-term infrared camouflage in complex environments. Full article

The continuous advancement of modern weaponry has intensified the pursuit of next-generation ballistic protection systems that integrate lightweight architectures, superior flexibility, and high energy absorption efficiency. This review provides a technological overview of current trends in the design, processing, and performance optimization of metallic, ceramic, polymeric, and composite materials for ballistic applications. Particular emphasis is placed on the role of advanced surface coatings and nanostructured interfaces as enabling technologies for improved impact resistance and multifunctionality. Conventional materials such as high-strength steels, alumina, silicon carbide, boron carbide, Kevlar^®, and ultra-high-molecular-weight polyethylene (UHMWPE) continue to dominate the field due to their outstanding mechanical properties; however, their intrinsic limitations have prompted a transition toward nanotechnology-assisted solutions. Functional coatings incorporating nanosilica, graphene and graphene oxide, carbon nanotubes (CNTs), and zinc oxide nanowires (ZnO NWs) have demonstrated significant enhancement in interfacial adhesion, inter-yarn friction, and energy dissipation. Moreover, multifunctional coatings such as CNT- and laser-induced graphene (LIG)-based layers integrate sensing capability, electromagnetic interference (EMI) shielding, and thermal stability, supporting the development of smart and adaptive protection platforms. By combining experimental evidence with computational modeling and materials informatics, this review highlights the technological impact of coating-assisted strategies in the evolution of lightweight, high-performance, and multifunctional ballistic armor systems for defense and civil protection. Full article

This review presents a critical and comparative analysis of carbon-based electrochemical sensing platforms for the determination of heavy metal ions in water, with emphasis on Pb²⁺, Cd²⁺, and Hg²⁺. The growing discharge of industrial and mining effluents has led to persistent contamination of aquatic environments by toxic metals, creating an urgent need for sensitive, rapid, and field-deployable analytical technologies. Carbon-based nanomaterials, including graphene, carbon nanotubes (CNTs), and MXene, have emerged as key functional components in modern electrochemical sensors due to their high electrical conductivity, large surface area, and tunable surface chemistry. Based on reported studies, typical detection limits for Pb²⁺ and Cd²⁺ using differential pulse voltammetry (DPV) on glassy carbon and thin-film electrodes are in the range of 0.4–1.2 µg/L. For integrated thin-film sensing systems, limits of detection of 0.8–1.2 µg/L are commonly achieved. MXene-based platforms further enhance sensitivity and enable Hg²⁺ detection with linear response ranges typically between 1 and 5 µg/L, accompanied by clear electrochemical or optical signals. Beyond conventional electrochemical detection, this review specifically highlights self-sustaining visual sensors based on MXene integrated with enzyme-driven bioelectrochemical systems, such as glucose oxidase (GOD) and Prussian blue (PB) assembled on ITO substrates. These systems convert chemical energy into measurable colorimetric signals without external power sources, enabling direct visual identification of Hg²⁺ ions. Under optimized conditions (e.g., 5 mg/mL GOD and 5 mM glucose), stable and distinguishable color responses are achieved for rapid on-site monitoring. Overall, this review not only summarizes current performance benchmarks of carbon-based sensors but also identifies key challenges, including long-term stability, selectivity under multi-ion interference, and large-scale device integration, while outlining future directions toward portable multisensor water-quality monitoring systems. Full article

Electron transport in carbon nanotubes (CNTs) is highly sensitive to interactions with their local environment, making them promising candidates for sensing applications. Specifically, this could allow detection of electrochemically and optically inert compounds that typically require complex and expensive analytical techniques. In this study, we examine how single-walled carbon nanotubes (SWCNTs) respond to perfluorooctanoic acid (PFOA), a common per- and polyfluoroalkyl substance (PFAS). To improve sensitivity, we employ a single/few-CNT device setup where a small number of SWCNTs were aligned across nanogaps between gold electrodes with the dielectrophoresis method. This structure addresses the challenges of large CNT networks, such as inter-CNT interactions, drift, and degradation, resulting in improved stability for practical applications. Results showed that device resistance drops as a function of PFOA concentrations. Additionally, positive gate voltage enhances sensitivity by attracting negatively charged PFOA molecules to the SWCNT surface. Specifically, we report that the sensitivity increases by nearly an order of magnitude under a 0.3 V gate bias. Impedance spectroscopy reveals distinct amplitude and phase signatures, enabling selective detection of PFOA among different analytes. Applying gate voltage further enhances sensor selectivity, highlighting the potential of gated SWCNT devices for accurate and selective environmental monitoring. The device demonstrates promising performance as a robust platform for creating single/few-CNT nanosensors for detecting electrochemically and optically inert substances like PFAS molecules. Full article

The application of bioinspired nanocomposites in orthopedic implants marks a significant innovation in biomedical engineering, aimed at overcoming long-standing limitations of conventional implant materials. Traditional implants frequently suffer from poor osseointegration, mechanical mismatch with bone, and vulnerability to infection. Bioinspired nanocomposites, modeled after the hierarchical structures found in natural tissues such as bone and nacre, offer the potential to enhance mechanical performance, biological compatibility, and implant functionality. This study reviews and synthesizes current advancements in the design, fabrication, and functionalization of bioinspired nanocomposite materials for orthopedic use. Emphasis is placed on the integration of nanocrystalline hydroxyapatite (nHA), carbon nanotubes (CNTs), titanium dioxide (TiO₂) nanotubes, and other nanostructured coatings that mimic the extracellular matrix. Methods include comparative evaluations of mechanical properties, surface modifications for biocompatibility, and analyses of antibacterial efficacy through nano-topographical features. Bioinspired nanocomposites have been shown to improve osteoblast adhesion, proliferation, and differentiation, thereby enhancing osseointegration. Nanostructured coatings such as TiO₂ nanotubes increase surface hydrophilicity and corrosion resistance, supporting long-term implant stability. Mechanically, these composites offer high stiffness, superior wear resistance, and improved strength-to-weight ratios. Biomimetic combinations of hydroxyapatite, zirconia, and biopolymers have demonstrated effective load transfer and reduced stress shielding. Additionally, antibacterial functionality has been achieved via nanostructured surfaces that deter bacterial adhesion while remaining cytocompatible with host tissues. The integration of bioinspired nanocomposites into orthopedic implants provides a multifunctional platform for enhancing clinical outcomes. These materials not only replicate the mechanical and biological properties of native bone but also introduce new capabilities such as infection resistance and stimuli-responsive behavior. Despite these advancements, challenges including manufacturing scalability, long-term durability, and regulatory compliance remain. Continued interdisciplinary research is essential for translating these innovations from laboratory to clinical practice. Full article

The incorporation of carbon nanotubes (CNTs) enhances the mechanical properties of cement-based materials by inhibiting micro-crack propagation. Machine learning provides an efficient approach for predicting the compressive strength of CNT-reinforced concrete, yet existing studies often lack important features and rely on less adaptive models. To address these issues, a multi-dimensional database (429 experimental data points) covering 11 factors (including cement mix ratio, CNT morphology, and dispersion process) was constructed. A hierarchical model verification and optimization was conducted: traditional regression models (Multiple Linear Regression, Multiple Polynomial Regression (MPR), Multivariate Adaptive Regression Splines), mainstream model (Support Vector Regression (SVR)), and ensemble learning models (Random Forest, eXtreme Gradient Boosting (XGB), Light Gradient Boosting Machine optimized by Particle Swarm Optimization (PSO)/Bayesian Optimization (BO)) are trained, compared, and evaluated. MPR performs best (test set R² = 0.856) among traditional regression models, while SVR (test set R² = 0.824) is less accurate. The highest accuracy in ensemble models is achieved by the PSO-optimized XGB model, with R² = 0.910 (test set). PSO outperforms BO in optimization precision, while BO is much more efficient. Water–cement ratio, age, and sand–cement ratio are the primary influencing factors for strength. Among CNT parameters, the inner diameter has greater impact than the length and outer diameter. Optimal CNT parameters are CNT–cement mass ratio 0.1–0.3%, inner diameter ≥ 7.132 nm, and length 1–15 μm. Surfactant polycarboxylate can increase strength, while OH⁻ functional groups can decrease it. These findings, integrated into the high-precision PSO-XGB model, provide a powerful tool for optimizing the mix design of CNT-reinforced concrete, accelerating its development and application in the industry. Full article

Shape memory polymers (SMPs) are a class of smart materials that exhibit unique shape-fixing and recovery abilities, attracting wide attention for applications in electronics, aerospace, and biomedical engineering. Chitosan (CS) as a renewable biopolymer, possessing good biocompatibility, biodegradability, and antimicrobial properties; its use as a matrix enhances the environmental compatibility and bio-adaptability of SMPs. MXene, as a novel two-dimensional material, is characterized by high electrical conductivity, abundant surface functional groups and good hydrophilicity, showing potential in energy storage, electromagnetic shielding and sensing. In this work, CS and poly (vinyl alcohol) (PVA) were used as the polymer matrix, and carbon nanotubes (CNTs) together with MXene were introduced as co-fillers to construct multifunctional composites. The effect of the CNTs/MXene hybrid fillers on mechanical properties, electromagnetic shielding and multi-stimuli-responsive shape memory behavior was systematically investigated. After ratio optimization, the composites showed excellent comprehensive performance: tensile strength reached up to 20.0 MPa, Young’s modulus up to 292.2 MPa, and maximum elongation at break of 23.2%; electromagnetic interference shielding effectiveness (SE_T) in the X-band (8.2–12.4 GHz) reached a maximum of 10.6 dB; shape fixation rates exceeded 90%; under thermal stimulation, a shape recovery ratio of 98.3% was achieved within 41.7 s; light-driven recovery rate reached 86.5% with a minimal recovery time of 82.3 s; under electrical stimulation the highest recovery rate was 94.1% with a shortest recovery time of 30 s. This study successfully prepared functional multi-stimuli-responsive shape memory composite films and provided a new strategy for the design of green smart materials. Full article

The search for high-capacity, stable anode materials is crucial for advancing lithium-ion battery (LIB) technology. Although carbon nanotubes (CNTs) are known for their excellent electrical conductivity and mechanical strength, their practical capacity is still limited. This study presents an advanced anode design by molecular functionalizing both single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) with tetrabromocobalt phthalocyanine (CoPc), resulting in CoPc/SWCNT and CoPc/MWCNT hybrid materials. Metal phthalocyanines (MPcs) are recognized for their tunable and redox-active properties. In CoPc, the redox-active metal centers and π-conjugated structure are uniformly attached to the CNT surface through strong π-π interactions. This synergistic combination significantly boosts the lithium-ion (Li-ion) storage capacity by offering numerous coordination sites for Li-ions and enhancing charge transfer kinetics. Electrochemical analysis shows that the CoPc-SWCNT active anode electrode material shows an impressive reversible capacity of 1216 mAh g⁻¹ after 100 cycles at a current density of 0.1 A g⁻¹, substantially surpassing the capacities of pristine CoPc (327 mAh g⁻¹) and a CoPc/MWCNT hybrid (488 mAh g⁻¹). Furthermore, the CoPc/SWCNT anode exhibited exceptional rate capability and outstanding long-term cyclability. These results underscore the effectiveness of non-covalent functionalization with SWCNTs in enhancing the electrical conductivity, structural stability, and active site utilization of CoPc, positioning CoPc/SWCNT hybrids as a highly promising anode material for high-performance Li-ion storage. Full article