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This work proposes a model describing the dynamic behavior of sensing films based on functionalized MWCNT networks in terms of conductivity when exposed to time-variable concentrations of NO2 and operating with variable working temperatures. To test the proposed model, disordered networks of MWCNTs functionalized with COOH and Au nanoparticles were exploited. The model is derived from theoretical descriptions of the electronic transport in the nanotube network, of the NO2 chemisorption reaction and of the interaction of these two phenomena. The model is numerically implemented and then identified by estimating all the chemical/physical quantities involved and acting as parameters, through a model fitting procedure. Satisfactory results were obtained in the fitting process, and the identified model was used to further the analysis of the MWCNT sensing in dynamical conditions.

The combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution. In this work, the charge transfer kinetics in the glassy carbon electrode (GCE) modified with Au(NPs)-multiwalled carbon nanotube (MWCNT) nanohybrid with varied concentrations of Au(NPs) in the range 40-100 nM was studied using electrochemical impedance spectroscopy (EIS). Field emission scanning electron microscopy and transmission electron microscopy confirmed the attachment of Au(NPs) on the surface of MWCNTs. The cyclic voltammetry and EIS results showed that the charge transfer mechanism was diffusion controlled and the rate of charge transfer was dependent on the concentration of Au(NPs) in the nanohybrid. The formation of spherical diffusion zone, which was dependent on the concentration of Au(NPs) in nanohybrids, was attributed to result in 3 times the increase in the charge transfer rate , 5 times increase in mass transfer, and 5% (9%) increase in I (I ) observed in cyclic voltammetry in 80 nM Au(NP) nanohybrid-modified GCE from MWCNT-modified GCE. The work was extended to probe the effect of charge transfer rates at various concentrations of Au(NPs) in the nanohybrid-modified electrodes in the presence of Escherichia coli. The cyclic voltammetry results clearly showed the best results for 80 nM Au(NPs) in nanohybrid electrode. The present study suggested that the formation of spherical diffusion zone in nanohybrid-modified electrodes is critical for the enhanced electrochemical biosensing applications.

In recent years, using nanomaterials based on multi-wall carbon nanotubes (MWCNT) through the activation of peroxymonosulfate (PMS) has attracted more attention to the degradation of organic pollutants. This research presented a new route for the synthesis of MWCNT/CoMn 2 O 4 nanocomposite for the degradation of picric acid using advanced oxidation processes (AOPs). Firstly, CoMn 2 O 4 nanoparticles were prepared and then loaded on MWCNT using ultrasonic waves. The results of various analyzes confirmed the successful loading of nanoparticles on carbon nanotubes. As the degradation process proceeds through oxidation processes, the high electronic conductivity of MWCNT and the active sites of Mn and Co in the nanocomposite play an essential role in activating PMS to generate reactive oxygen species (ROS). An investigation of the reaction mechanism in different conditions showed that the highest speed of picric acid decomposition in the presence of nanocomposite (98%) was in 47 min. However, the scavenger test showed that HO · and SO 4 ·− radicals are more important in the degradation process. Meanwhile, the results showed that removing picric acid using MWCNT/CoMn 2 O 4 was more effective than CoMn 2 O 4 alone and confirmed the interaction effect of MWCNT nanotubes with AB 2 O 4 nanocatalyst.

Thorough research on materials with negative permittivity is essential to address various application scenarios and their electromagnetic interference shielding capabilities must be carefully examined. This study focuses on the development of Bambuseae/MWCNT/MnFe 2 O 4 /PVA metacomposites through a simple sol–gel method. By adjusting the multi-walled carbon nanotubes (MWCNTs) content, the permittivity of the metacomposites was altered. When the MWCNT content was at 0.064 and 0.256 g, there was a noticeable observation of negative permittivity, mainly attributed to Lorentz model. The Bambuseae/MWCNT/MnFe 2 O 4 /PVA metacomposites showcased an exceptional shielding effectiveness of − 43.2827 dB for a thickness of 1 mm. The negative permittivity led to a significant impedance mismatch, causing the metacomposite surface to reflect the majority of electromagnetic waves. Moreover, the presence of plasma oscillations and the formation of conductive networks by MWCNTs enhanced the metacomposites’ ability to absorb electromagnetic waves within the material due to their high conductivity and polarization loss. Additionally, the Bambuseae/MWCNT/MnFe 2 O 4 /PVA metacomposites displayed remarkable optical-electrical conversion and remarkable durability in the production of flexible electronic devices like light-dependent resistors, indicating their potential use in harsh working conditions.

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs—both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites—was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs.

This study involves a novel CuO/CoFe₂O₄/MWCNTs (CCT) nanocomposite, developed by integrating cobalt ferrite (CoFe₂O₄) and copper oxide (CuO) nanoparticles onto multi-walled carbon nanotubes (MWCNTs), for the degradation of tetracycline (TC) under visible light. The photocatalyst was extensively characterized using XRD, HR-SEM, EDX, HR-TEM, UV-Vis, BET, and PL analysis. The synthesized CoFe₂O₄ and CuO nanoparticles exhibited crystallite sizes of 46.8 nm and 37.5 nm, respectively, while the CCT nanocomposite had a crystallite size of 53 nm. Microscopy confirmed a particle size of 49.2 nm for the nanocomposite, with MWCNTs measuring 15.65 nm in diameter. The band gap energy of the CCT nanocomposite was 1.6 eV, which contributed to its enhanced photocatalytic activity, as evidenced by the lower emission intensity in PL analysis. BET analysis revealed a pore volume of 0.37 cc/g and a surface area of 82.3 m²/g. Photocatalytic performance was tested across various conditions, with adjustments to nanocomposite dosages (0.1–0.5 g/L), TC concentrations (5–25 mg/L), and pH levels (2–10). Under optimized conditions (0.3 g/L CCT, 5 mg/L TC, pH 10, 120 min of visible light exposure), the CCT achieved 98.1% degradation of TC. The optimized parameters were subsequently used to assess TC degradation with individual photocatalysts: CoFe₂O₄, CuO, CT, and CCT. The enhanced photocatalytic efficiency observed can be largely attributed to the improved charge transfer dynamics and effective electron-hole separation facilitated by MWCNT doping. The reaction followed a pseudo-first-order kinetic model, with hydroxyl radicals (OH • ) identified as the key species in the degradation process. Moreover, the catalyst exhibited 96% retention of its photocatalytic efficiency after five consecutive cycles, demonstrating exceptional stability and reusability. These results emphasize the CCT composite’s potential as a highly efficient and sustainable photocatalyst for the remediation of pharmaceutical pollutants in aquatic systems.

In this study, we present a facile synthesis of a TiO 2 /SiO 2 /g-C 3 N 4 /MWCNT composite with dual functionality as both a photocatalyst and adsorbent for the effective elimination of pharmaceutical and dye pollutants from water. The composite was comprehensively characterized using FESEM, EDX, XRD, BET, FTIR, PL, and UV–Vis spectroscopy to elucidate its morphology, crystalline structure, and optical properties. The results revealed a hierarchical flower-like sphere/sheet architecture with an average crystallite size of about 21.3 nm. Multi-walled carbon nanotubes (MWCNTs) acted as visible-light photosensitizers, enhancing the separation efficiency of photogenerated electron–hole pairs. The influence of MWCNT content on photocatalytic activity was systematically investigated. The TiO 2 /SiO 2 /g-C 3 N 4 /MWCNT composite with 11 wt% CNT demonstrated superior visible-light degradation performance, achieving 92% efficiency for a 20 mg/L methylene blue (MB) aqueous solution significantly outperforming the MWCNT-free counterpart. Furthermore, the presence of MWCNTs remarkably improved tetracycline (TC) removal in CaCO 3 -rich water (20 mg/L TC with 300 mg/L CaCO 3 ). The high photocatalytic activity is attributed to the formation of abundant local junctions among g-C 3 N 4 , TiO 2 /SiO 2 , and MWCNTs, which facilitate efficient charge separation and migration through a direct Z-scheme mechanism under visible light illumination.

A hierarchical NiCo 2 O 4 @ZnS/MWCNT (NCO@Z-MWCNTs) nanocomposite was synthesized to serve as a platinum-free counter electrode for dye-sensitized solar cells (DSSCs). The nanocomposite comprised spinel NiCo 2 O 4 nanorods, ZnS associated with the surface of the nanorods, and an interconnected multi-walled carbon nanotube (MWCNT) network, and it was synthesized via a low-temperature solution-based hydrothermal method. XRD confirmed the presence of cubic NiCo 2 O 4 and zinc blende ZnS phases, while FESEM–EDS and XPS analyses verified the incorporation of ZnS and the formation of a conductive carbon framework interconnecting adjacent nanorods. ZnS, rather than acting as an isolated catalytic component, was considered to contribute additional sulfide-related surface sites and to modulate the interfacial electronic environment of the NiCo 2 O 4 nanorods, which likely facilitated redox reactions involving the I − /I 3 − couple. Meanwhile, the MWCNT network established continuous electron transport pathways, effectively reducing interfacial resistance and enhancing charge-transfer efficiency. Thermogravimetric and electrochemical analyses revealed enhanced thermal stability, improved redox kinetics, and a significant reduction in charge-transfer resistance compared with pristine NiCo 2 O 4 .The optimized NCO@Z–MWCNT 9wt% counter electrode achieved a power conversion efficiency of 10.03% under AM 1.5 G illumination, exceeding that of the Pt reference device (9.6%). Overall, the improved performance was attributed to the combined contributions of ZnS surface modification and the conductive MWCNT network, which together enhanced charge transport and electrocatalytic activity. This work demonstrates a scalable strategy for developing cost-effective, durable, and high-performance counter electrodes for dye-sensitized solar cells.

This investigation elucidates a novel methodology for augmenting the tribological and mechanical attributes of epoxy composites via selective functionalization of multi‐walled carbon nanotubes (MWCNTs). The study optimizes wear mechanisms and friction‐induced graphitization by incorporating pristine (P‐MWCNTs), carboxyl‐functionalized (COOH‐MWCNTs), amine‐functionalized (NH₂‐MWCNTs), and silane‐modified MWCNTs. Composites were characterized for tensile strength, compressive strength, surface hardness, coefficient of friction (COF), and specific wear rate (SWR). Incorporation of 0.3 wt.% COOH‐MWCNTs yielded optimal performance, reducing SWR by 82% (0.07 × 10⁻⁶ mm³ N⁻¹·m⁻¹ at 8 Hz) and COF by 32% (0.37 at 10 N) relative to neat epoxy (SWR: 0.50 × 10⁻⁶ mm³ N⁻¹·m⁻¹, COF: 0.66 at 15 N). Enhanced dispersion, interfacial adhesion, and tribofilm formation account for superior tensile strength (≈90 MPa) and hardness (≈88 Shore D). X‐ray diffraction and transmission electron microscopy validated friction‐induced graphitization and partial structural degradation above 10 N. Applications encompass self‐lubricating bushings, protective coatings, and wear‐resistant surfaces for automotive and industrial components. Future investigations should target enhanced compressive strength and load‐bearing capacity. Incorporating 0.3 wt.% COOH‐functionalized MWCNTs, well dispersed via ultrasonication, into epoxy significantly enhances tribological and mechanical performance, reducing wear by 82% and COF by 32%. During sliding, friction breaks down MWCNTs into graphitic fragments, which are slowly released, forming a protective tribofilm. These composites excel in automotive, aerospace, and industrial applications requiring strength and low friction.

This work is a comprehensive review of sensing materials, which interact with several target gases pertinent to agricultural monitoring applications. Sensing materials which interact with carbon dioxide, water vapor (relative humidity), hydrogen sulfide, ethylene and ethanol are the focus of this work. Performance characteristics such as dynamic range, recovery time, operating temperature, long-term stability and method of deposition are discussed to determine the commercial viability of the sensing materials considered in this work. In addition to the sensing materials, deposition methods are considered to obtain the desired sensing material thickness based on the sensor’s mechanism of operation. Various material classes including metal oxides, conductive polymers and carbon allotropes are included in this review. By implementing multiple sensing materials to detect a single target analyte, the issue of selectivity due to cross sensitivity can be mitigated. For this reason, where possible, it is desirable to utilize more than one sensing material to monitor a single target gas. Among those considered in this work, it is observed that PEDOT PSS/graphene and TiO2-coated g-C3N4 NS are best suited for CO2 detection, given their wide dynamic range and modest operating temperature. To monitor the presence of ethylene, BMIM-NTf2, SWCNTs and PtTiO2 offer a dynamic range most suitable for the application and require no active heating. Due to the wide dynamic range offered by SiO2/Si nanowires, this material is best suited for the detection of ethanol; a gas artificially introduced to prolong the shelf life of the harvested crop. Finally, among all other sensing materials investigated, it observed that both SWCNTs and CNTs/SnO2/CuO are most suitable for H2S detection in the given application.