Search Results (1,897)

This work reports a systematic study concerning the synthesis of pure polyaniline ultrafine nanofibers (PANI-NFs) and their nanocomposites with oxygen-functionalized carbon nanotubes (PANI-NFs/O-MWCNTs) using diluted chemical polymerization and hydrothermal processes. We investigated the synergistic effects of various synthesis parameters, such as the concentration of the ammonium persulfate oxidant agent and growth temperature, on the physical, chemical, and electrochemical properties of the resulting products through structural, morphological, spectroscopic, and electrochemical characterization. Our study revealed the successful synthesis of thermally resistant polyaniline ultrafine nanofibers (PANI-NFs) in the form of emeraldine salt (ES), exhibiting a mean diameter in the range of 8–17 nm. The PANI-NFs and PANI-NFs/O-MWCNT nanocomposites demonstrated excellent electrochemical properties, with specific capacitances of up to 0.94–1.23 F cm⁻² and 1410–2074 F/g, respectively, and with good rate capability. These characteristics are confirmed by the relaxation time constant τ₀ (41 and 8 ms, respectively) and lower internal R₀/interfacial charge transfer R_Փ resistances of around 0.2 Ω, as well as diffusion coefficients of around 10⁻⁷ and 3.7 × 10⁻⁷ cm²/s. This breakthrough in nanofiber synthesis paves the way for practical applications in diverse domains, from high-performance energy storage to biosensing and beyond, where the unique electroactive properties of the nanocomposites can be leveraged to achieve exceptional results. Full article

Flexible electrode materials with tailored electrical and mechanical properties are essential for reliable electrocardiographic (ECG) sensing. In this work, p-toluenesulfonic-acid-doped polypyrrole (PPy–TSA) films were modified using polymeric and inorganic fillers, as well as their combinations (polyethylene glycol, graphene, carbon nanotubes, and zeolite), to tune their functional performance. The reference PPy–TSA film exhibits typical morphological and chemical characteristics of doped polypyrrole and serves as a reliable baseline for comparison. All composite films retain electrical conductivity within the range required for ECG applications while showing improved mechanical compliance (i.e., enhanced ability to conform to the skin and sustain deformation). Based on the optimized balance between electrical and mechanical properties, flexible ECG electrodes were fabricated using the TSA-doped PPy-based composite film. ECG recordings obtained with the several proposed electrodes show good agreement with those acquired using a commercial ECG electrode, demonstrating the potential of PPy-based composite films for flexible bioelectronic sensing applications. Full article

Modern bioimplants increasingly depend on surface-engineered functionality to elicit adaptive biological responses. One promising strategy involves the electrodeposition of bioresponsive elements such as magnesium (Mg), which plays a critical role in osseointegration. In this study, we present a novel approach for modifying anodized zirconia nanotubes (ZrNTs) via Mg decoration using electrochemical deposition. A controlled pulsed cathodic linear sweep protocol was employed to control Mg deposition behaviour, enabling reduced clustering and improved spatial distribution. Notably, ultraviolet (UV) irradiation was found to influence Mg adsorption dynamics, revealing a distinct pattern of interaction. Comprehensive surface characterization was conducted to assess nanotube morphology, Mg adherence, and distribution. These modified surfaces were subsequently evaluated for their potential in further functionalization, targeting surface chemistries conducive to biomaterial viability. The biomineralization capacity of Mg-decorated ZrNTs was systematically investigated using electrochemical impedance spectroscopy (EIS) and Tafel analysis, demonstrating enhanced apatite formation and improved corrosion resistance. This work establishes Mg decoration of ZrNTs as a viable route for developing bioactive, corrosion-resistant implant surfaces. Full article

From bacteria to higher vertebrates, cells have developed different systems to communicate with each other and transmit specific signals in a dynamic interplay with neighborhood cells. This review focuses on cell-to-cell communication mediated by nanotubes, membrane protrusions present during evolution from bacteria to higher plants and animals. We describe the basic structure of nanotubes in different organisms and cell types and their functions, which cover transfer of signaling molecules, ions, organelles and pathogens in a cell- and context-dependent manner, thereby promoting cell survival, tissue development, response to stress, pathogens’ spreading and drug resistance. We also provide an overview of recent studies that are broadening our understanding of the role of these conduits in the pathogenesis of high-incidence diseases in humans, such as cancer and neurodegeneration. Full article

For the first time, hybrid nanocomposites based on poly(2,5-dichloro-3,6-bis(phenylamino)-p-benzoquinone) (PCPAB) and multi-walled carbon nanotubes (MWCNTs) were obtained and the influence of the preparation method on their structure and functional properties was demonstrated. The nanocomposites were obtained both by ultrasonic mixing of PCPAB and MWCNTs, and via in situ oxidative polymerization of CPAB in the presence of MWCNTs or MWCNTs with the addition of ZnO. The formation of hybrid nanocomposites occurs due to non-covalent interaction (π-stacking) between the graphene structures of the MWCNT surface and the phenyl rings of PCPAB. It was found that during the in situ oxidative polymerization of CPAB in the presence of MWCNTs, the growth of polymer chains occurred in close proximity to the filler surface, which led to the formation of a polymer coating. ZnO particles, localized on MWCNTs, on the one hand, prevent their aggregation, and on the other hand, create additional polymerization reaction centers due to the coordination of the Zn-O bond at the H and O atoms of the monomer. An increase in the concentration of reaction centers as a result led to a 2–2.5-fold reduction in the induction polymerization period. According to SEM data, in this case, a more ordered and denser polymer layer is formed due to intermolecular complexation between the main and side chains of the growing polymer with the participation of Zn²⁺ ions formed as a result of the transformation of ZnO to ZnCl₂ in the acidic reaction medium of polymerization. The results of the study of the frequency dependences of conductivity indicate a hopping mechanism of conductivity of nanocomposites. The electrical conductivity of nanocomposites depends on their production method and the MWCNT content and varies between 0.5 and 1.1 S∙cm⁻¹, which is 6–12 times higher than the conductivity of the original polymer. Thermogravimetric analysis revealed that the nanocomposites exhibit enhanced thermal stability compared to PCPAB. The best results were shown by nanocomposites with a higher content of MWCNTs, for which the residual mass at 450 °C was 51–53%. Full article

Naturally occurring halloysite nanotubes (HNTs), a clay mineral characterized by a unique dual-charge architecture, offer a promising strategy for enhancing the performance of composite polymer electrolyte (CPE). In this work, HNTs are introduced as a low-cost, functional filler to simultaneously address two key limitations of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based CPE: low ionic conductivity and inadequate lithium-ion transference number. The negatively charged outer surface of HNTs facilitates Li⁺ transport, while the positively charged inner lumen confines anions such as TFSI⁻. Controlled acid etching (6 M HCl, 12 h) further optimizes this structure by removing surface impurities and enlarging the lumen, thereby enhancing both charge-directed ion transport pathways. The resulting HNT-modified CPE achieves a high ionic conductivity of 6.1 × 10⁻⁴ S⋅cm⁻¹ and a Li⁺ transference number of 0.73. When assembled into Li||CPE||LiFePO₄ cells, the electrolyte enables stable cycling over 300 cycles at 0.2C, retains 119.2 mAh/g at 2C, and delivers 85.7 mAh/g even at 5C, demonstrating excellent cycling stability and rate capability. This study reveals the potential of mineral-derived nanomaterials, with their inherent structural and physicochemical properties, to serve as key functional components in high-performance batteries. Full article

The concurrent challenges of environmental pollution and energy scarcity necessitate advanced sustainable technologies. Photocatalytic fuel cells (PFCs) offer a promising route by coupling pollutant degradation with energy recovery. However, the synergistic interplay between anode intrinsic properties and macroscopic polarization effects remains inadequately understood. Herein, a BiOBr-doped TiO₂ nanotube array photoanode with engineered oxygen vacancies was developed to construct a synergistically enhanced PFC system. XPS, EPR, and DFT analyses confirm the formation of oxygen vacancies and favorable band bending, inducing an internal electric field that markedly promotes charge separation and interfacial reaction kinetics. As a result, the charge separation efficiency is enhanced by approximately fourfold relative to pristine TiO₂ nanotube arrays. Under the combined action of the internal electric field and self-bias-induced polarization field, photogenerated electrons and holes undergo directional transport and effective utilization. The optimized PFC achieves 78% sulfamethoxazole degradation within 180 min, representing a 1.38-fold improvement. Degradation pathways and toxicity evolution were further elucidated using LC–MS and Fukui function analysis, highlighting the critical role of electric field-driven charge regulation in high-performance PFCs. Full article

A hybrid material based on the copolymerization of EDOT (3,4-ethylenedioxythiophene) and Py (pyrrole), 1:1 monomer ratio, onto multi-walled carbon nanotubes (MWCNTs) was synthesized through a multistep functionalization approach. The resulting P(EDOT-co-Py)@MWCNT hybrid, poly(3,4-ethylenedioxythiophene-co-pyrrol)@MWCNT hybrid, was characterized by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). These characterizations confirmed the successive functionalization steps, the effective anchoring of the monomers, and the subsequent formation of the copolymer. Transmission electron microscopy (TEM) images revealed a homogeneous polymer coating along the nanotube surface while preserving the structural integrity of the MWCNTs throughout the functionalization and polymerization processes. The P(EDOT-co-Py)@MWCNT hybrid was evaluated as an active electrode material for aluminum-ion storage in an aqueous aluminum sulfate electrolyte. The system exhibited two distinct charge-storage mechanisms: at high current densities, proton surface adsorption dominated, whereas at lower rates, a faradaic contribution associated with polymer chain redox activity and the reversible extraction/insertion of Al³⁺ became prevalent. The hybrid electrode delivered high specific capacities, reaching 200.6, 106.3, and 44.3 mAh g⁻¹ at 0.10, 0.25, and 0.50 A g⁻¹, respectively. These values are comparable to—or even exceed—those reported for similar cathodic materials designed for Al³⁺ storage, highlighting P(EDOT-co-Py)@MWCNT hybrid as a highly promising cathode candidate for aqueous aluminum-ion energy-storage systems. Full article

The flexible foam piezoresistive sensor demonstrates significant potential for wearable strain-sensing applications due to its substantial deformation capacity, excellent flexibility, and cost effectiveness. However, conventional flexible foam piezoresistive sensors often struggle to simultaneously achieve high sensitivity, a wide pressure detection range, fast response and long-term stability. This paper employed a glucose-based sugar-templating method to fabricate a fine-pore (50 μm) foam structure complemented by a dual-filler strategy to enhance overall performance. A robust porous conductive network was constructed by embedding zinc oxide (ZnO) and multi-walled carbon nanotubes (MWCNTs) into a polydimethylsiloxane (PDMS) matrix. The resulting sensor exhibits outstanding piezoresistive properties, featuring a wide linear detection range (0–80% strain) and a high sensitivity of 9.02 kPa⁻¹ within the 0–10 kPa pressure range. It demonstrates rapid response/recovery times of 50/70 ms and maintains stable output performance even after 5000 compression cycles at 300 kPa. The sensor also exhibits negligible environmental interference and excellent long-term stability. When attached to finger joints, feet soles, or the throat, the sensor enables functions such as finger bending recognition, race-walking violation discrimination, gait analysis, and vocal fold vibration recognition, thereby demonstrating its considerable potential for application in human–computer interaction and human motion detection. Full article

Metamaterials possess unique and desirable multiphysical behaviors derived from deliberately arranging conventional materials into designed structural topologies. Multifunctional mechanical metamaterials that can both carry load and provide in situ state awareness are increasingly needed for applications such as structural health monitoring and soft robotic systems. To address the demand for multifunctional metamaterials, this study reports a scalable fabrication strategy for self-sensing lattice metamaterials by conformally dip-coating 3D-printed flexible cells with a carbon nanotube (CNT)–styrene–ethylene–butylene–styrene (SEBS) nanocomposite. Scanning electron microscopy shows that the coating conforms closely to the printed struts with well-dispersed CNT networks. The electromechanical behavior of coated Octet, Kelvin, and auxetic unit cells was characterized under quasi-static cyclic uniaxial compression (0–40% strain). All the coated structures exhibited highly stable, reversible, and repeatable piezoresistive response, with a near-linear relationship between resistance change and strain. Among the tested geometries, the auxetic unit cell achieved the highest strain sensitivity that was approximately four times that of the Octet cell and six times that of the Kelvin cell. To evaluate scalability, auxetic lattices containing eight scaled auxetic unit cells were shown to retain high sensitivity and remained statistically similar to the unit cell. This study demonstrates that the strain sensing performance of nanocomposites can be engineered through lattice topology using a simple dip-coating functionalization approach, enabling scalable self-sensing metamaterials for large-scale and conformal sensing applications. Full article

This study investigates the synergistic effect of functionalized carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and carbon fibers (CFs) on the mechanical performance of cement-based composites through a multivariate optimization approach. All carbon allotropes were covalently functionalized via acid treatment to enhance dispersion and interfacial bonding with the cement matrix. A face-centered central composite design (FCCD) combined with response surface methodology (RSM) was employed to systematically evaluate the influence of the three reinforcements, each varied between 0.033 wt.% and 0.067 wt.%, with a total carbon content not exceeding 0.2 wt.% of cement. The statistical analysis revealed a negligible correlation between reinforcement content and flexural strength (explained variance ≈ 1%), whereas fracture energy and compressive strength showed stronger dependencies, with explained variances of 25% and 66%, respectively. The maximum experimental fracture energy reached 18.1 J, corresponding to an increase of nearly 800% compared to plain cement, obtained at the highest combined reinforcement content. Compressive strength improved up to 48 MPa (≈32% higher than the reference), with the model predicting potential enhancements up to 40% under optimized compositions. The regression analysis highlighted the dominant role of quadratic and interaction terms, indicating that mechanical performance is governed more by synergistic effects than by the linear contribution of individual components. These findings demonstrate that controlled co-dispersion of multiple functionalized carbon allotropes enables significant enhancement of cement mechanical properties at very low total carbon contents, providing a cost-effective strategy for the design of high-performance cementitious composites. Full article

To ensure the viability of polymer materials, given the properties and limitations of polymers, hybrid materials have been developed that blend the features of all included components. Researchers have not explored the impacts of the length aspect ratio of nanofillers on the mechanical properties of hybrids in great detail previously. Multi-walled carbon nanotubes are a valuable option because they exhibit improved mechanical properties. Using numerical simulation, the impacts of nanofiller content and the size aspect ratio on two base materials—polyamide 6, polyoxymethylene—and their blends, were determined as a function of the volume ratio, the MWCNTs aspect ratio and the base material blend composition. Numerical analysis employed the ANSYS Material Designer. Random samples of chopped-fibre representative volume elements were generated, meshed and analysed by finite element analysis to obtain the Young’s modulus and Poisson’s ratio for each sample. The results showed a generally linear dependence. Rises in both aspect ratio and volume fraction of MWCNTs increased the Young’s modulus up to 46% and decreased the Poisson’s ratio up to 1.6%. The findings suggest that although the impact of the aspect ratio is not as large as that of the volume ratio, longer MWCNTs are preferable. Full article

Silicon-based materials offer exceptional theoretical capacity for lithium-ion batteries (LIBs), but their practical application remains severely hindered by large volume expansion, low electrical conductivity, and unstable solid electrolyte interphase (SEI) formation during cycling. Herein, a binder-free silicon-containing carbon composite anode (denoted as CP-Si@C-4, where CP represents the conductive carbon paper substrate) is designed: carbon constitutes the structural and conductive framework, while silicon nanoparticles serve as a functional alloying component contributing characteristic lithiation/delithiation behavior. This framework comprises a conductive carbon paper (CP) scaffold, a resin-derived carbon matrix for homogeneous silicon dispersion, an interconnected carbon nanotube (CNT) network enabling long-range electron transport, and a conformal chemical vapor deposition (CVD) carbon layer for interfacial stabilization. Rather than simply increasing the overall carbon content, a series of control electrodes with distinct carbon configurations are deliberately designed to decouple the respective roles of bulk stress buffering and particle-level interfacial stabilization during cycling. The results indicate that functionally differentiating and coordinately regulating these two functions is critical for achieving durable binder-free silicon-containing carbon composite anodes. Benefiting from this cooperative multidimensional carbon architecture, the optimized CP-Si@C-4 anode delivers an initial Coulombic efficiency (ICE) of 86.3% and maintains a reversible capacity of ~990 mA h g⁻¹ at 2 A g⁻¹ after 1000 cycles. This work provides a structural design concept for improving long-term stability in binder-free silicon-containing carbon composite anodes. Full article

Coiled carbon nanotubes and their entwined derivatives have attracted attention for their excellent mechanical properties and potential applications. Hydrogenation is an effective way to modify the mechanical response of CCNTs, but its effect on the tensile performance and energy absorption of ECCNTs remains unclear. In this study, molecular dynamics simulations are used to systematically investigate the regulatory effects of hydrogenation and entanglement on the tensile properties and energy absorption capacity of CCNTs and ECCNTs. Different hydrogenation degrees and structural configurations are designed for comparative analysis. Results show that hydrogenation exerts a dual regulatory effect on single CCNTs: moderate hydrogenation enhances tensile strength and total energy absorption, while excessive hydrogenation leads to brittleness, reduced ductility, and impaired energy dissipation. Entanglement significantly improves the tensile load-bearing capacity and energy absorption of CCNTs, with ECCNTs showing 1.5–2.0 times higher spring constants than single CCNTs. Among the ECCNT models, ECCNT2 achieves an optimal balance between tensile stiffness, ductility, and energy absorption efficiency. This study clarifies the mechanistic roles of hydrogenation and entanglement, providing valuable guidance for the rational design of high-performance CCNT-based structural and functional nanomaterials. Full article

This study presents a sustainable, battery-free UV (ultraviolet) dose sensor designed for intelligent food packaging applications. The device integrates laser-induced graphene (LIG) electrodes, a ZnO-CNT (carbon nanotube) UV-active composite, and a bio-derived ionochromic cell composed of blueberry anthocyanins and a NaCl electrolyte. This work advances the platform by introducing a quantitative and predictive dose–color mapping framework for cumulative UV detection under zero-bias operation. A controlled charge-injection protocol was employed to emulate UV-generated photocurrent, enabling systematic investigation of charge-transfer-driven ionochromic kinetics across five current levels (0.2–3 mA). HSB (hue–saturation–brightness)-based colorimetric analysis was performed to quantify the time-dependent chromatic evolution, and a numerical fitting model was developed to map charge accumulation to color shifts. Using this calibration, the color response at microampere-level photocurrents—corresponding to real zero-bias UV operation—can be predicted. The resulting model enables estimation of the cumulative time required for the ionochromic cell to transition from red to purple under realistic UV intensities. By combining self-powered sensing with predictive colorimetric modeling, this work significantly enhances the functionality of battery-free UV indicators, enabling quantitative dose measurement without external electronics for safer food-supply-chain monitoring. Full article