Nanotube Hybrid Research Articles

Preparation and Characterization of Graphene and Carbon Nanotube Hybrid Polydimethylsiloxane Composites for Protective Coating Applications

In this work, the synergistic effect of graphene nanosheets (GNs), as well as multiwalled carbon nanotubes (MWCNTs), as reinforcing agents of polydimethylsiloxane (PDMS) was investigated, in order to explore the possibilities of designing composite materials, tailored for use in the field of coatings, which might be, in fact, a very interesting application. It was shown that the addition of GNs and MWCNTs in PDMS matrices significantly improves the thermal stability of the obtained nanocomposites, especially those reinforced exclusively with GNs. The tensile tests indicated that strength increased for all the examined composites. It was also observed that the Young’s moduli had an increasing trend, with the exception of the composites containing only GNs, while those reinforced solely with MWCNTs exhibited the best performance. The O2 permeability measurements revealed that the highest reduction in the permeability was observed in GN-MWCNT/PDMS composite membranes, in comparison to those reinforced only with graphene or carbon nanotubes. Dielectric relaxation spectroscopy showed that all the examined composites, and especially those of MWCNTs, possess electrical conductivity, apart from the samples reinforced exclusively with graphene. The electromagnetic shielding effectiveness was also improved at higher filler loadings, which is more evident in composites reinforced with MWCNTs. It was concluded that the improved properties of the above studied hybrid composites make them suitable for protective coating applications.

Enhanced electrochemical sensor based on Uio-66-NH2/carbon nanotubes hybrid for selective detection of ofloxacin

Enhanced electrochemical sensor based on Uio-66-NH2/carbon nanotubes hybrid for selective detection of ofloxacin

Effect of W concentration on the thermal stability of Cu-carbon nanotube hybrids

Carbon nanotube (CNT)-metal hybrids have been increasingly focused as a promising candidate for flexible circuit, but the metal agglomeration is their main failure mode under elevated temperature. In this study, we found the thermal stability of Cu-CNT hybrids can be significantly enhanced by W alloying. For CNT-Cu hybrids, the nano-grains suffered from serious agglomeration and growth after annealing at 473 K. And this phenomenon could be more significant by increasing annealing temperature. By adding W atoms with 4 at% into Cu matrix, the grain growth is weakened during annealing and the agglomeration is suppressed even at the temperature of 673 K. As the W content increases, the agglomeration is further suppressed at the higher temperature (873 K). The mechanism for the improved thermal stability was related to the stabilized grain boundaries by W atoms that were dissolved into Cu during deposition and further precipitated at higher W content or/and higher annealing temperatures.

Synergistic Fe/Fe3C@Fe‐NC@Carbon Nanotube Heterostructure for Enhanced CO2 Capture and Mineral Recovery from Desalination Brine

AbstractMetal recovery coupled with CO2 mineralization from sustainable sources, such as seawater, has garnered significant attention from environmental science and resource utilization perspectives. Herein, an earth‐abundant and efficient Fe/Fe3C@Fe‐N‐codoped carbon@carbon nanotube (Fe/Fe3C@Fe‐NC@CNT) hybrid cathodic catalyst is introduced for electrochemically extracting magnesium and calcium from desalination brine while capturing CO2 to produce valuable Mg(OH)2 and CaCO3. The Fe/Fe3C@Fe‐NC@CNT, featuring the combination of single‐atomic Fe sites and graphitic layer‐wrapped Fe/Fe3C nanoparticles encapsulated within N‐doped mesoporous carbon tubes, achieves over 90% of Ca2+ and Mg2+ metal cations recovery efficiency at 25 mA cm−2 for 6 h. More importantly, the Fe/Fe3C@Fe‐NC@CNT hybrid catalyst efficiently suppresses the competitive hydrogen evolution side reaction even at high currents and boasts a wider operating potential range compared to benchmark Pt/C, enhancing the metal recovery efficiency and CO2 capture capability. These findings underscore the potential of the Fe/Fe3C@Fe‐NC@CNT hybrid catalyst in revolutionizing brine management and waste stream handling, offering a promising and sustainable solution to these critical environmental challenges.

Bi2Te3/Carbon Nanotube Hybrid Nanomaterials as Catalysts for Thermoelectric Hydrogen Peroxide Generation.

Harnessing waste heat from environmental or industrial sources presents a promising approach to eco-friendly and sustainable chemical synthesis. In this study, we introduce a thermoelectrocatalytic (TECatal) system capable of utilizing even small amounts of heat for hydrogen peroxide (H2O2) production. We developed a nanohybrid structure, combining carbon nanotubes (CNTs) and Bi2Te3 nanoflakes (Bi2Te3/CNTs), through a one-pot synthesis method. Bi2Te3, as a thermoelectric (TE) material, generates charge carriers under a temperature gradient via the Seebeck effect, enabling them to participate in surface redox reactions. However, the rapid recombination of these charge carriers greatly limits the TECatal activity. In the Bi2Te3/CNTs nanohybrid system, the introduction of CNTs substantially enhances the efficiency of H2O2 production, as the strong bonding between CNTs and Bi2Te3, along with the excellent conductivity of CNTs, facilitates charge carrier separation and transport, as confirmed by TE electrochemical tests. This study underscores the significant potential of thermoelectric nanomaterials for converting waste heat into green chemical synthesis.

Construction of multi-functional silicone rubber/reduced graphene oxide/multi-walled carbon nanotube composites with segregated structure by surfactant-free Pickering emulsion method

Polymer composites with segregated structure (PC–S) have the advantages of low filler usage and excellent functionality. Emulsion blending combined with direct molding technology is the main method for the preparation of PC-S. However, due to the high fluidity of low-viscosity silicone rubber (SR), PC-S cannot be prepared by this technique. In addition, surfactants affect the heat resistance of the final SR composites (SRC). In order to solve the above problems, in this study, a Pickering emulsification combined with pre-crosslinking technology for SR was successfully developed by using graphene oxides (GO)/multi-walled carbon nanotubes (MWCNTs) hybrid fillers (GM) as emulsifiers, and SR/reduced GO (RGO)/MWCNTs composites with segregated structure (SSGM) were prepared. When RGO content is 4.5 wt%, MWCNTs content is 3.2 wt%, SSGM shows the highest electrical conductivity of 12.5 S/m, the highest electromagnetic interference shielding efficiency (EMI SE) of 41.4 dB, and an excellent flame retardant performance. The whole preparation process avoids the use of organic solvents and surfactants, which reduces the production cost of SSGM and the environmental pollution, and provides a feasible preparation route for the industrialized production of SSGM.

Photo-thermal and temperature-regulated sodium alginate-g-mPEG/carbon nanotube hybrid fibers with improved tensile strength

Despite the remarkable potential of phase change fibers for energy storage, their practical deployment has been hindered by two crucial challenges: inadequate external thermal stimulation to induce phase transition and leakage of the phase-change material. In this study, we successfully incorporated carbon nanotubes (CNTs) into a solution of sodium alginate grafted polyethylene glycol monomethyl ether (SA-g-mPEG) and utilized wet spinning processing to fabricate CNTs/SA-g-mPEG hybrid fibers with enhanced photo-thermal conversion and robust solid-solid phase change capabilities. Upon exposure to sunlight for merely 60 s, the hybrid fibers achieved a remarkable peak temperature of 40 °C. Upon cessation of sunlight exposure, these fibers demonstrated a gradual release of thermal energy, thereby underlining their exceptional photothermal conversion and temperature regulation capabilities. Furthermore, DSC analysis revealed that, at an optimal grafting ratio of 36.6 %, the hybrid fibers exhibited ΔHc and ΔHm values of 48.23 J/g and 50.83 J/g, respectively. Notably, hybrid fibers with a grafting ratio of 20.2 % demonstrated substantial enhancements in tensile properties, achieving a maximum breaking strength of approximately 2.02 cN/dtex—an impressive 11.3 % increase compared to SA-g-mPEG composite fibers. Our findings suggest that CNTs/SA-g-mPEG hybrid fibers hold immense promise for applications in body heat storage, fabric temperature regulation, and related fields.

Selective Synthesis of 3D Aligned VO2 and V2O5 Carbon Nanotube Hybrid Materials by Chemical Vapor Deposition.

3D carbon nanotube hybrid materials containing VO2 and V2O5 evenly distributed onto vertically aligned carbon nanotubes (VACNTs) is reported. Adjustable loading of particles in controllable sizes and shapes onto the VACNTs was developed via a stepwise chemical vapour deposition (CVD) approach. Solid VO(acac)2 is chosen as vanadium source. CO2 acts as reactive gas for the pre-functionalisation of the VACNTs. The process temperature was identified as key parameter to control the deposited vanadium oxide phase. A temperature of 550 °C results in monoclinic VO2, while 600 °C results in the deposition of V2O5 onto the VACNT support. The morphology and the amount of deposited material was found to be dependent on the reactor dimensions and the degree of functionalisation of the carbon support. An increase of the D/G ratio of the VACNT from 0.75 to 1.08 caused by a CO2 treatment step within the process led to an increase of the particle coverage from a scarce coverage without prior CO2 treatment to a dense coverage of the VACNT support after 15 min of CO2 exposure time. Size and crystallinity of the as deposited particles can be further adjusted by a controlled heat treatment after VO(acac)2 precursor deposition.

Miniaturized Electrochemical Gas Sensor with a Functional Nanocomposite and Thin Ionic Liquid Interface for Highly Sensitive and Rapid Detection of Hydrogen.

Hydrogen has been widely used in industrial and commercial applications as a carbon-free, efficient energy source. Due to the high flammability and explosion risk of hydrogen-air mixtures, it is vital to develop sensors featuring fast-responding and high sensitivity for hydrogen leakage detection. This paper presents a miniaturized electrochemical gas sensor by elaborately establishing a nanocomposite and thin ionic liquid interface for highly sensitive and rapid electrochemical detection of hydrogen, in which a remarkable response time and recovery time of approximately 6 s was achieved at room temperature. A screen-printed carbon electrode was modified with a reduced graphene oxide-carbon nanotube (rGO-CNT) hybrid and platinum-palladium (Pt-Pd) bimetallic nanoparticles to realize high sensitivity. To achieve miniaturization and high stability of the sensor, a thin-film room-temperature ionic liquid (RTIL) was employed as the electrolyte with a significantly decreased response time. The fast-responding hydrogen sensor demonstrates excellent performance with high sensitivity, linearity, and repeatability at concentrations below the lower explosive limit of 4 vol %. The engineered high-performance interface and gas sensor provide a promising and effective strategy for gas sensor design and rapid hazardous gas monitoring.

Single-walled carbon nanotubes hybrid carbon materials sensor for simultaneous detection of chloramphenicol and furazolidone in food samples

Single-walled carbon nanotubes hybrid carbon materials sensor for simultaneous detection of chloramphenicol and furazolidone in food samples

Single walled carbon nanotubes/ZnO nanowires heterostructure array for NO2 gas sensing at low ppm levels

A layer-by-layer ZnO nanowire (NW)-Single Walled Carbon Nanotube (CNT) hybrid gas sensor has been proposed for effective detection of NO2 gas under a low exposure limit of 5 ppm. The fabricated hybrid sensor displayed good sensor response (S %), good selectivity and fast response time towards the target gas. S % value of 36.4 % under 5 ppm NO2 level at 250 °C and good selectivity response towards different interfering gases like SO2, CO and H2 have been observed. Meanwhile, fast response time values of 44.08 s (response) and 62.11 s (recovery) were observed at 300 °C under 5 ppm NO2 level. The sensor baseline resistance of the hybrid heterostructure (HS) was also found to be lower when compared to that of a bare ZnO NW sensor. In addition, the presence of Single Walled CNT in the HS was also shown to reduce the operational temperature of the sensor. Temperature played a significant role by controlling the adsorption and desorption kinetics of gas molecules on the surface. Moreover, the formation of p-n interface between Single Walled CNT (p-type) and ZnO NW (n-type) might have modulated the potential charge barrier on interacting with the adsorbed gases which inturn might have impacted the response of the hybrid sensor. In addition, the large surface areas offered by both NWs and nanotubes might have improved the gas adsorption capability thereby enhancing the overall hybrid sensor’s response.

Plasma-assisted preparation of amidoxime-carbon nanotubes hybrids for effective uranium extraction

Nowadays, the urgent requirement of uranium resource has received much attention with the development of growing industry and global low-carbon energy. Designing high-performance adsorbents could be a potential way for effective and available uranium acquisition from seawater. Herein, a green and highly efficient plasma technology was utilized to assist the amidoxime groups (AO) grafting on carbon nanotubes (CNTs), which avoided the cumbersome processes and the use of polluting reagents in traditional methods. The findings confirmed the introduction of oxygen-bearing functional groups on CNTs by plasma without any destruction of the basic structure. On the other hand, the adsorption performance was remarkably enhanced after the graft of AO groups, which was attributable to the valid chelation among the AO groups and uranium. The as-prepared CNTs-AO adsorbent showed the splendid maximum adsorption capacity of 275.98 mg/g at the conditions of pH = 6.0 and 303 K, which is higher than the adsorption capacity of raw CNTs (120.12 mg/g). Besides, the possible interaction mechanisms between CNTs-AO with U(VI) were investigated, and the adsorption process was ascribed to the synergism of abundant oxygen- and nitrogen-containing functional groups in AO groups on CNTs. Additionally, CNTs-AO was test to possess a great recyclability that was significant for its practical applications. This work would provide a reference for feasible preparation of outstanding adsorbents by a facile plasma-induced grafting method.

Enhancing thermo-physical properties of hybrid nanoparticle-infused medium temperature organic phase change materials using graphene nanoplatelets and multiwall carbon nanotubes

Phase change materials (PCMs) have emerged as an intriguing option for the storage of thermal energy because of their remarkable capacity to store latent heat. However, the practical application of these materials is hindered by their low thermal conductivity and limited photo-absorbance. For this investigation, graphene nanoplatelets (GNP) and multiwall carbon nanotubes (MWCNT) hybrid nanoparticles were disseminated in RT-54HC organic PCMs at different weight fractions. The nanoparticles were incorporated into the base PCMs using a melt blending technique. Based on the findings, one combination of GNP to MWCNT in a 0.25:0.75 ratio has shown the highest thermal conductivity, with an increase of 40% (0.28 Wm−1 K−1) compared to other hybrid combinations. This breakthrough could potentially open new avenues in the field of thermal energy storage. The chemical stability of the hybrid nanoparticle dispersed composites was assessed through FTIR analysis. In addition, the composites exhibited excellent thermal stability, maintaining their structural integrity even at temperatures as high as 300 ℃. The melting temperature of the composites also showed minimal variation. Based on the evaluation of latent heat enthalpy, the organic PCM known as base RT-54HC demonstrated a heat storage capacity of 230 J/g. However, the composites exhibited a slight decrease in latent heat with increasing nanoparticle weight fraction. In addition, the composite with added hybrid nanoparticles demonstrated an increase in optical absorbance, accompanied by a decrease in transmissibility. Therefore, the hybrid nano-enhanced composites have demonstrated enhanced thermo-physical properties, making them not only suitable but also highly promising for use in applications with mid-range melting temperatures.Graphical

Microstructure-mechanical property relationships of polymer nanocomposite reinforced with lyophilized montmorillonite/carbon nanotubes hybrid particles

Abstract Introducing multi-walled carbon nanotubes (MWCNT) and montmorillonite (MMT) simultaneously into a polymer can significantly enhance its properties. Meanwhile, choosing the best technique to homogeneously disperse these nanohybrid particles in polymers, without agglomerates, is still a challenge. In this study, a hybrid MMT/MWCNT, prepared by lyophilization process, is introduced in polylactide (PLA). Morphology of the resulting nanocomposites displays synergistic relationships of the MMT/MWCNT, facilitating dispersion in PLA. The analysis of transmission electron microscopy (TEM) specific particle densities of PLA0.5hyb, PLA1.0hyb, and PLA2.0hyb shows values of 77, 64, and 35 µm⁻2, respectively. This suggests that MMT platelets are significantly more exfoliated in PLA0.5hyb compared to the other nanocomposites. It also indicates that filler aggregation increases as the MMT/MWCNT concentration increases. Compared to neat PLA, elastic modulus of nanocomposites increased by up to 46 %, demonstrating the reinforcing effect of MMT/MWCNT hybrid nanofillers. The nanocomposites exhibit viscosity, plasticity and damage phenomena, which are significantly decreased because of the MMT/MWCNT incorporation, compared to neat PLA. Furthermore, the viscoelastic properties, analyzed by dynamic thermal-mechanical analysis, record about 27 % increase in the storage modulus of the nanocomposites compared to PLA, indicating the effectiveness of the hybrid MMT/MWCNT in increasing the resistance of PLA/MMT/MWCNT nanocomposite against thermomechanical aggression.

Second harmonic scattering reveals different orientational orders inside the hydrophobic cavity of hybrid nanotubes.

Second Harmonic Scattering (SHS) is a suitable technique to investigate the orientational correlations between molecules. This article explores the organization of different dye molecules adsorbed within the hydrophobic porosity of a hybrid organic-inorganic nanotube. Experimental polarization resolved SHS measurements highlight different orientational orders ranking from highly ordered and rigid organizations to disordered assemblies. Microscopic models of assemblies inside the pores are presented and discussed in the context of orientational correlation between the dye molecules. This work shows that the degree of order in the nanotube cavity follows the molecule's affinity within the porosity.

WITHDRAWN: Characterization of Ag2O nanorods/TiO2 nanotubes hybrid coating for potential orthopedic implant applications

In this study, the potential of nanorod/nanotube hybrid arrays for orthopedic coatings was explored. The Ag2O nanorods/TiO2 nanotubes (ANRs/TNTs) hybrid coating was synthesized on Ti6Al7Nb using a multi-step procedure involving primary anodization, annealing, and secondary anodization processes. The process began with primary anodization, fostering the growth of TNTs, succeeded by thermal treatment for crystallization, and deposition of an Ag layer using physical vapor deposition (PVD) magnetron sputtering. Subsequently, secondary anodization was conducted on Ti6Al7Nb, which was initially coated with Ag-deposited TNTs, culminating in the formation of a hybrid coating. In the hybrid coating, the mean inner diameter of the TNTs was measured at 32.2 ± 8.0 nm, while the average inner diameter of the ANRs stood at 59.0 ± 30.6 nm. The hybrid coating exhibited notably higher hardness values (75.8 ± 3.2 HV) compared to both anodic TNTs (HV 45.5 ± 1.0) and crystallized TNTs (HV 54.0 ± 1.6), while its adhesion strength reached 871.5 ± 3.86 MPa, highlighting robust bonding with Ti6Al7Nb. In vitro bioactivity results confirmed bone-like apatite layer formation on ANRs/TNTs hybrid coating after 14 days in simulated body fluid (SBF), indicating enhanced bioactivity. These findings open promising avenues for advanced orthopedic coatings, with potential applications in facilitating osseointegration, drug delivery, and localized treatments in future biomedical applications.

Electrochemical determination of 4-nitrophenol using functionalized graphene oxide/functionalized multi-walled carbon nanotubes hybrid material modified glassy carbon electrode

Herein, a novel carboxylated multi-walled carbon nanotubes-carboxylated graphene oxide coated glassy carbon electrode (f-MWCNTs/f-GO/GCE) was prepared for electrochemical determination of 4-nitropehenol (4-NP). The sensor was characterized using fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), raman spectroscopy, and powder x-ray diffraction (XRD). Electrochmical experiments were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. The resulting f-MWCNTs/f-GO/GCE could be performed for quick, sensitive, and selective determination of 4-NP in the presence of other electroactive compounds. 4-NP was electrochemically detected depending on the reduction of 4-NP at −0.65 V potential using amperometric method. Under the optimum condutions, the sensor showed excellent response to the determination of 4-NP with three linear detection ranges from 0.018 to 700 µM. The sensor exhibited extremely low limit of detection (5.4 nM). Also, the fabricated sensor was used for detection of 4-NP in different water samples.

Biomimetic anisotropic hydrogel as a smart self-healing agent of sustainable cement-based infrastructure

The durability improvement of cement-based infrastructure is an effective strategy to achieve sustainable development and reduce the carbon footprint. In this work, a biomimetic anisotropic hydrogel, alginate/polyacrylamide/halloysite nanotubes hybrid hydrogel (SA/AM/HNTs-RDC), was fabricated as a self-healing agent to enhance the self-healing ability and extend the service life of cement-based infrastructure. The effects of SA/AM/HNTs-RDC hydrogel on the formation and deposition of healing products and the self-healing behavior of cement in the different conditions (water condition and CO2-rich condition) were investigated. Compared with the matrix hydrogel (alginate/polyacrylamide, SA/AM), the crosslinking ions and anisotropic microstructure of SA/AM/HNTs-RDC hydrogel can stimulate the massive formation and dense deposition of healing products (ettringite (AFt) and monosulfo aluminate (AFm) in the simulated water condition, calcite and AFt in CO2-rich condition) to accelerate the performance recovery of the damaged construction. The self-healing measurements exhibited that the cracks around 200 μm in the cement paste with 1 % anisotropic hydrogel (RDC1) can be sealed completely after 14-day-curing in water, and its recovery ratio of the compressive strength increased by about 10 % compared with control samples. In CO2-rich condition, the closure rate of cracks was accelerated and the complete healing of cracks with similar width only needed 7 days. The compressive strength recovery increased by 13.7 % over control samples.

Rational Design of a Co/MnO-Embedded 2D Nitrogen-Doped Carbon/Carbon Nanotube Hybrid Catalyst for Efficient Oxygen Catalysis and High-Capacity Zn–Air Batteries

Rational Design of a Co/MnO-Embedded 2D Nitrogen-Doped Carbon/Carbon Nanotube Hybrid Catalyst for Efficient Oxygen Catalysis and High-Capacity Zn–Air Batteries

A high-power hybrid carbon nanotube/three-dimensional reduced graphene oxide glucose/O2 enzymatic biofuel cell

Long-lasting, high-performance enzymatic biofuel cells (EBFCs) are among the most promising candidates for renewable and green power generation. There are two main drawbacks to EBFCs: 1) short enzyme lifetime due to the enzyme's (protein) denaturation; and 2) low electron transfer efficiency as the enzyme's active site is deeply buried inside the non-conductive protein structure of the enzyme. In this study, a hybrid of carbon nanotubes (CNT) and three-dimensional graphene (3DG) was used to immobilize the glucose oxidase (GOx) on the surface of a glassy carbon electrode (GCE) to fabricate a modified bioanode in a glucose/O2 EBFC. This facile and low-cost CNT/3DG hybrid is a solution to the problems of instability, short lifespan, and poor electron transport in EBFCs. The exceptional electrocatalytic activity of the porous CNT/3DG hybrid is demonstrated by its effective immobilization of GOx and ability to collect energy from glucose oxidation by direct electron transfer (DET) while preserving the structure of the enzyme. The CNT acts like a tiny electrical wire that reaches and harvests the electron directly from the flavin adenine dinucleotide (FAD) (the redox center of GOx) and transfers it to the electrode surface, thus enhancing the performance of the EBFC. The immobilized GOx lifetime was increased to 210 days with a maximum power density of 253.36 µWcm-2 at 0.65 V. These results demonstrate the attractive capability of the CNT/3DG hybrid in the development of efficient biofuel cells and biosensors that employ enzymes in their structures.