Carboxylated Carbon Nanotubes Research Articles

Strong, Lightweight, and Shape-Memory Bamboo-Derived All-Cellulose Aerogels for Versatile Scaffolds of Sustainable Multifunctional Materials.

Strong, lightweight, and shape-memory cellulose aerogels have great potential in multifunctional applications. However, achieving the integration of these features into a cellulose aerogel without harsh chemical modifications and the addition of mechanical enhancers remains challenging. In this study, a strong, lightweight, and water-stimulated shape-memory all-cellulose aerogel (ACA) is created using a combination strategy of partial dissolution and unidirectional freezing from bamboo. Benefiting from the firm architecture of cellulose microfibers bridging cellulose nanofibers /regenerated cellulose aggregated layers and the bonding of different cellulose crystal components (cellulose Iβ and cellulose II), the ACA, with low density (60.74mg cm-3 ), possesses high compressive modulus (radial section: 1.2MPa, axial section: 0.96MPa). Additionally, when stimulated with water, the ACA exhibits excellent shape-memory features, including highly reversible compression-resilience and instantaneous fold-expansion behaviors. As a versatile scaffold, ACA can be integrated with hydroxyapatite, carboxyl carbon nanotubes, and LiCl, respectively, via a simple impregnation method to yield functionalized cellulose composites for applications in thermal insulation, electromagnetic interference shielding, and piezoresistive sensors. This study provides inspiration and a reliable strategy for the elaborately structural design of functional cellulose aerogels endows application prospects in various multifunction opportunities.

The structure and hydrophilicity of MWCNT-COOH /TiO2 modified PVDF membrane

MWCNT-COOH/TiO2 modified PVDF ultrafiltration membrane was created using a blended modification process with carboxyl carbon nanotubes (MWCNT-COOH) and TiO2 nanoparticles as modification additives in order to further enhance the hydrophilicity of the PVDF membrane surface. Using the techniques of scanning electron microscopy, Fourier transform infrared spectrum, and a water angle of engagement analyzer, the membrane’s structure and hydrophilicity were identified. Investigations were conducted into the effects of various MWCNT-COOH dosages on membrane structure and hydrophilicity. The results of the investigation indicated that 0.03 g of MWCNT-COOH in the casting solution was the ideal dose. The manufactured MWCNT-COOH/TiO2 modified PVDF ultrafiltration membrane had the best hydrophilicity.

Green functionalization for chelating ligand-like and π-conjugated active sites on carbon nanotubes and its use for vanadium redox flow batteries

An imide bond-based functional group is proposed for the catalyst's active site in vanadium redox flow batteries (VRFBs). Based on the functional group's inherent property produced by the optimized process, the catalytic activity toward vanadium ion redox reaction (VIRR) on both sides was increased sixfold without adversely affecting VIRR reversibility in comparison to the raw material, carboxylic acid-functionalized carbon nanotubes. These advantages were attributed to the imide bond-based functional groups acting as a chelating ligand to form strong interactions with vanadium redox couples while also inducing facile electron transfer by the π-conjugated bonds, resulting in increased catalytic activity and reversibility. Moreover, the treatment used an eco-friendly process comprising low-cost precursors (citric acid and urea) and mild conditions (80 °C, 2 h), thereby improving the commercial availability of VRFBs. In VRFB driving tests, the fabricated electrode outperformed the electrode with a polymer-like structure in terms of catalytic activity and long-term stability due to leaching of the active sites from the latter. Overall, the proposed catalyst could be a practical option for enhancing VRFB performance based on a low-cost and eco-friendly treatment method.

Synergistic catalysis and detection of hydrogen peroxide based on a 3D-dimensional molybdenum disulfide interspersed carbon nanotubes nanonetwork immobilized chloroperoxidase biosensor

Enzyme-based electrochemical biosensors are promising for a wide range of applications due to their unique specificity and high sensitivity. In this work, we present a novel enzyme bioelectrode for the sensing of hydrogen peroxide (H2O2). The molybdenum disulfide nanoflowers (MoS2) is self-assembled on carboxylated carbon nanotubes (CNT) to form a three-dimensional conductive network (3D-CNT@MoS2), which is modified with 1-ethyl-3-methylimidazolium bromide (ILEMB), and followed by anchoring chloroperoxidase (CPO) onto the nanocomposite (3D-CNT@MoS2/ILEMB) through covalent binding to form a bioconjugate (3D-CNT@MoS2/ILEMB/CPO). The ILEMB modified 3D-CNT@MoS2/ILEMB has good hydrophilicity and conductivity, which not only provides a suitable microenvironment for the immobilization of CPO but also facilitates the direct electron transfer (DET) of CPO at the electrode. The 3D-CNT@MoS2/ILEMB/CPO bioconjugate modified electrode has a high catalytic efficiency for H2O2. Through electroenzymatic synergistic catalysis for H2O2 detection by 3D-CNT@MoS2/ILEMB/CPO-GCE, a wide detection range of 0.2 μmol·L−1 to 997 μmol·L−1 and a low detection limit of 0.097 μmol･L−1 with high sensitivity of 1050 µA·mmol·L−1·cm−2 were achieved. Additionally, the 3D-CNT@MoS2/ILEMB/CPO-GCE displayed exceptional stability, selectivity, and reproducibility. Furthermore, 3D-CNT@MoS2/ILEMB/CPO-GCE is suitable for sensing of H2O2 in human urine s with good recovery, suggesting its potential application for the detection of H2O2 in biomedical field.

High specific surface area MXene/SWCNT/cellulose nanofiber aerogel film as an electrode for flexible supercapacitors

Transition metal carbonitrides (MXene) with two-dimensional layered structures are a recent research topic in the field of supercapacitors. However, because MXene can easily self-stack, its capacitance performance is affected. To this end, one-dimensional cellulose nanofibers (CNF) and carboxylic single-walled carbon nanotubes (SWCNT) were used to intercalate MXene to obtain well-dispersed MXene/SWCNT/CNF aqueous suspensions and their hybrid hydrogels, and to obtain hybrid aerogels through supercritical drying. CNF gives aerogel excellent porosity, a high specific surface area (301.03 m2 g−1), good electrolyte infiltration, and gentle mechanical flexibility, while SWCNT imparts high conductivity to aerogel film. We assembled a symmetrical all-solid-state flexible supercapacitor and interdigitated micro-supercapacitors using an aerogel film as a flexible electrode. The area specific capacity of the above electrode reaches 746.68 mF cm−2 and 244.50 mF cm−2, respectively. This study provides a fabrication method of polymer–inorganic hybrid nanocomposite aerogel film electrodes for flexible supercapacitors.

Sensitive and highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto carbon nanotube-coated porous paper working electrodes

Rapid detection of indoor airborne viruses is critical to prevent the spread of respiratory diseases. Herein, we present sensitive, highly rapid electrochemical measurement of airborne coronaviruses through condensation-based direct impaction onto antibody-immobilized, carbon nanotube-coated porous paper working electrodes (PWEs). Carboxylated carbon nanotubes are drop-cast on paper fibers to make three-dimensional (3D) porous PWEs. These PWEs have higher active surface area-to-volume ratios and electron transfer characteristics than conventional screen-printed electrodes. The limit of detection and detection time of the PWEs for liquid-borne coronaviruses OC43 are 65.7 plaque-forming units (PFU)/mL and 2 min, respectively. The PWEs showed sensitive and rapid detection of whole coronaviruses, which can be ascribed to the 3D porous electrode structure of the PWEs. Moreover, water molecules condense on airborne virus particles during air sampling, and these water-encapsulated virus particles (<4 µm) are impacted on the PWE for direct measurement without virus lysis and elution. The whole detection takes ∼10 min, including air sampling, at virus concentrations of 1.8 and 11.5 PFU/L of air, which can be due to the highly enriching and minimally damaging virus capture on a soft and porous PWE, demonstrating the potential for the rapid and low-cost airborne virus monitoring system.

Starch-derived photoresponsive high-efficientcy hygroscopic hydrogel for all-weather atmospheric water harvesting

Atmospheric water harvesting (AWH) technology, a new strategy to address the scarcity of fresh water, can be used to collect water from ambient air to produce clean water. Materials with moisture absorption-desorption capabilities are the key to AWH technology. Therefore, this paper reports a starch-derived photoresponsive atmospheric water-harvesting material with an acrylic acid (AA)/acrylamide (AM)-grafted starch hydrogel as the backbone, carboxylated carbon nanotubes (FCNTs) as the solar absorber, and lithium chloride (LiCl) as the water absorber. It was found that the hydrogel had good hygroscopicity in the relative humidity range of 25%–90%, and the adsorption capacity reached 8.5 g g−1 at 90% relative humidity. This hydrogel could recycle collected water vapor, and its performance and economy were found to be better than those of most reported atmospheric water harvesting materials. This material is driven by solar energy to release adsorbed water, and more than 94% of the adsorbed water was released quickly over a wide solar intensity range of 0.5–2 kW m−2. When used in the natural environment during the night/day cycle, this hydrogel was reversibly hygroscopic and achieved clean water production. This highlights the potential of biopolymers for atmospheric water harvesting applications.

Highly sensitive and stretchable strain sensor based on modified carboxylic carbon nanotubes/chitosan/polyurethane yarn

Although several strain sensors based on carbon nanotubes have been reported, it is still a great challenge to fabricate strain sensors possessed with large workable strain range, high sensitivity and stability. Herein, we developed a highly elastic strain and high sensitivity sensor based on stretchable spandex yarns manufactured by an easy layer-by-layer assembly method. Effects of multi-walled carboxylic carbon nanotubes and chitosan on sensor’s properties were investigated. The prepared sensor exhibited fascinating comprehensive sensing performance, including large workable strain range (∼115%), superior sensitivity (gauge factor up to 159 at 0–40% strain and 8175 over 100% strain), In addition, it still exhibited good work stably after 3500 cycles at strain of 50%. The sensor can detect both large and small scale human motions, including joint movement, phonation, swallowing, and drinking.

Interfacial Modification and Bending Performance of 3D Orthogonal Woven Composites with Basalt Filament Yarns.

To improve their interfacial properties, 3D orthogonal woven fabrics with basalt filament yarns were modified with functionalized carboxylated carbon nanotubes (KH570-MWCNTs) and polydopamine (PDA). Fourier infrared spectroscopy (FT-IR) analysis and scanning electron microscopy (SEM) testing were used. It was demonstrated that both methods could successfully modify basalt fiber (BF) 3D woven fabrics. The 3D orthogonal woven composites (3DOWC) were produced with epoxy resin and 3D orthogonal woven fabrics as raw material by the VARTM molding process. The bending properties of the 3DOWC were tested and analyzed by experimental and finite element analysis methods. The results showed that the bending properties of the 3DOWC modified by KH570-MWCNTs and PDA were significantly improved, and the maximum bending loads were increased by 31.5% and 31.0%. The findings of the finite element simulation and the experiment results were in good agreement, and the simulation error value was 3.37%. The correctness of the finite element simulation results and the model's validity further reveal the material's damage situation and damage mechanism in the bending process.

Amphiphilic polymers facilitated solid-phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry for direct extraction and analysis of zearalenone and zearalanone in corn juice samples.

In this work, amphiphilic polymers synthesized from carboxylated carbon nanotubes stabilized high internal phase emulsions are demonstrated to be capable of direct extracting zearalenone and zearalanone in samples consisting of an oil-water emulsion system. Under optimal conditions, the maximum adsorption capacities for zearalenone and zearalanone are 17.27 and 13.26mg/g. The adsorption is mainly attributed to π-π interaction, hydrophobic interaction, and hydrogen-bonding interaction for zearalenone and zearalanone. The adsorption isotherms reveal that the adsorption of zearalenone and zearalanone on amphiphilic polymers synthesized from carboxylated carbon nanotubes stabilized high internal phase emulsions follows Freundlich model with multilayer and heterogeneous adsorption due to the presence of multiple kinds of adsorption sites. The relative recoveries of the spiked zearalenone and zearalanone in corn juice samples range from 85% to 93% with relative standard deviations lower than 3.52%. The results manifest the high efficiency of amphiphilic polymers synthesized from carboxylated carbon nanotubes stabilized high internal phase emulsions for the adsorption and separation of analytes in the oil-water emulsion system. This study provides a new perspective on adsorbent engineering for the adsorption application in heterogeneous media.

Porous carboxylated carbon nanotubes hydrogel microspheres for removing U(VI) from aqueous solutions

Porous carboxylated carbon nanotubes hydrogel microspheres for removing U(VI) from aqueous solutions

Advanced hemocompatible polyethersulfone composite artificial lung membrane with efficient CO2/O2 exchange channel constructed by modified carbon nanotubes network

Artificial lung membranes as the core module of the extracorporeal membrane oxygenation technology (ECMO) execute the function of extracorporeal blood-gas barrier accomplishing CO2/O2 exchange with blood. However, the unsatisfactory hemocompatibility and difficulty in functionalization are the prominent challenges faced by current artificial lung membrane materials. In this study, polyethersulfone (PES) composite membranes with self-anticoagulant property and high gas exchange efficient are fabricated by blending PES matrix with poly(vinylamine) (PVAm) modified carboxylic carbon nanotubes (mCNTs) and citrate-based poly(octamethylene-citrate) (POC) pre-polymers. The mCNTs construct specific gas transfer channels within the composite membranes to enhance the gas permeability, while the POC pre-polymers provide anticoagulant property based on the chelation to blood Ca2+ and the inactivation effect to intrinsic coagulation factors. Importantly, directed by the actual ECMO gas exchange mode, we design a gas-liquid convectional circulation device that could evaluate gas exchange efficiency for the composite membranes under mimetic ECMO state. Therefore, this strategy not only proposes a new design method of advanced artificial lung membranes to solve the practical challenges in the current ECMO technology, but also establishes a scientific testing method to evaluate the gas exchange performance for new-type artificial lung membrane materials in the future.

CHF enhancement of CNT-COOH nanofluids in the boiling experiment with a downward-facing heating surface

The effects of carboxylated carbon nanotube (CNT-COOH) nanofluids prepared with various surfactants were researched on the pool boiling heat transfer coefficients (HTC) and critical heat fluxes (CHF). Sodium dodecyl sulfate (SDS), and gum arabic (GA) were used to improve the dispersion and stability of CNT-COOH nanofluids. Then, preparing different weight concentrations of each nanofluid (CNT-COOH/GA-water and CNT-COOH/SDS-water nanofluid) and investigated for their thermal performance. The result shows that the CHF of both nanofluids was significantly increased in a specific concentration range. Furthermore, the CNT-COOH/SDS-water nanofluids have lesser pool boiling HTC compared with reverse osmosis (R.O.) water, and CNT-COOH/GA-water nanofluids slightly increase at 0.005 g/L and 0.02 g/L. By conducting roughness and hydrophilia of the heating surface tests, it is speculated that the CNT-COOH deposition produced during the boiling process is the main reason for affecting HTC and CHF. The deposition has a complex hydrophilic microstructure, which makes the water droplets entering the interior can take away a large amount of heat on the heating surface and then enhance CHF.

A smart composite coating with self-reporting and self-healing functions to enhance corrosion protection for magnesium alloys

Smart coatings play crucial roles in realizing excellent corrosion protection on metals and alloys. However, the preparation of smart composite coatings exhibiting self-reporting and self-healing dual function still remains a challenge. Herein, a novel smart composite coating was successfully fabricated by incorporating the ionic liquid grafted carboxylated carbon nanotube and phenolphthalein into a micro-arc oxidation coating (MAO/PP/CCNT-IL) for AZ31B Mg alloy protection. The electrochemical tests including potentiodynamic polarization and electrochemical impedance spectroscopy reveal that the MAO/PP/CCNT-IL composite coating shows the best corrosion protection on the AZ31B Mg substrate among all coatings prepared in this work. In addition, the salt spray experiment in 5 wt% NaCl solution suggests that the occurrence of conspicuous pink within only 12 min can rapidly warn microdamage and microsurface damage, exhibiting a self-reporting effect. Meanwhile, the smart coating also presents outstanding healing property by reacting CCNT-IL with Mg ions from the substrates to generate the chelates to be covered on the damaged area. Such a smart coating offers a feasible strategy for prolonging the service lifetime of Mg alloys through a convenient, economical and effective way with a promising application in the field of material protection.

Study on Interfacial Properties of Carbon Nanotube Modified Epoxy Resin/T1000 Carbon Fiber Composites

This study was made on domestic T1000 carbon fiber to investigate its surface condition, precursor, multifilament, fiber/resin contact angle, fiber/resin interfacial shear strength and interlaminar shear strength. Analysis was carried out to examine the surface physical state of domestic T1000 carbon fiber, the micro-scale interfacial properties and mechanical properties of the composites. The results show that domestic T1000 grade carbon fiber has no inherent characteristic defects such as visible bumps, rough edges or grooves on its surface. It can obtain higher tensile strength. The fiber/resin interfacial test shows that carboxylated carbon nanotubes are well dispersed in the epoxy resin matrix by physical method. The mixed resin matrix has good wettability on carbon fibers and the contact angle of the composite interface decreases. The interfacial shear strength of SYT65 carbon fibers/resin increases by 10.6%, and the interlaminar shear strength increases by 15.7%. Toray T1000 carbon fiber/resin interfacial shear strength increases by 6.1%, and interlaminar shear strength increases by 14.1%. Compared with Toray T1000, the resin system used in this study is more compatible with SYT65 carbon fiber, which can give full play to the mechanical properties of SYT65 carbon fiber.

DFT study of carboplatin encapsulation interactions with carboxylated carbon nanotubes and conjugated to folic acid for targeted nano delivery systems

In this study, a nano-drug delivery design based on (8, 8) carboxylated single-walled carbon nanotube (CNT-COOH) and folic acid (FA) decorated on CNT-COOH (CNT-FA) were investigated. These nanocarriers were applied to enhance therapeutic efficacy and reduce the adverse effects of the anticancer drug carboplatin (CBP) and the results were compared. The density functional theory (DFT) calculations were used to calculate the interactions between CNT-COOH, CNT-FA, and the CBP anticancer drug. The DFT computations were carried out by the DMol3 module using annealing and force field; universal in Material Studio 2017. The negative adsorption value of CBP by CNT-COOH and CNT-FA demonstrated that the physisorption configuration was stable and the drug-nanotube sidewall interaction was a spontaneous process. The current study investigated the adsorption strength and energy between the CBP molecule and CNT-COOH (8, 8) nanotubes with diameters of 12.160 Å and 11.674 Å and CNT-FA with diameters of 11.874 Å and 10.608 Å in the gas phase based on DFT calculations. The HOMO and LUMO energies of all compounds were obtained by the DMol3 module based on DFT-D. Also, sigma profile calculations (σ), energy gap (ΔEgap), and molecular electrostatic potentials (MEP) of CBP, CNT-COOH, CBP/CNT-COOH, CNT-FA, and CBP/CNT-FA were calculated. The results of ΔEgap confirmed the higher activity of the CBP/CNT-FA component (0.243 eV) compared to other structures. Molecular docking simulations between nano-carriers, including with or without CBP, and the crystal structure of human folate receptor alpha (FR, PDB ID: 4LRH), were performed. The results exhibited CNT-FA and CBP/CNT-FA were stronger on folate receptor compared with CNT-COOH and CBP/CNT-COOH, respectively.

Electrochemical immunosensor based on Fe3O4/MWCNTs-COOH/AuNPs nanocomposites for trace liver cancer marker alpha-fetoprotein detection

An electrochemical biosensor based on iron tetroxide (Fe3O4)/carboxylated carbon nanotubes (MWCNTs-COOH)/gold nanoparticles (AuNPs) was designed for the detection of alpha-fetoprotein (AFP), which is often used as an important indicator for the early clinical diagnosis of liver cancer markers. The Fe3O4/MWCNTs-COOH nanocomposite was synthesized by a solvothermal method and it combined with gold nanoparticles (AuNPs) deposited at the constant potential on a glassy carbon electrode to form Fe3O4/MWCNTs-COOH/AuNPs, which intensifies the electrical signal while the large active sites enable more stable immobilization of the AFP monoclonal antibodies on the electrode. The electrochemical performance of Fe3O4/MWCNTs-COOH/AuNPs was investigated in detail and the electrochemical response signal after the immune reaction with the AFP antigen-antibody was recorded. The peak current Ip of the response signal is linearly proportional to the lgcAFP in the range of 1 pg mL−1–10 μg mL−1, with a detection limit of 1.09034 pg mL−1 and good performance in clinical sample testing. The proposed sensor has shown great application and development potential in clinical medicine field.

A Colorimetric Paper Sensor Based on Self‐assembled Nanocomposite Pd−Pt@hemin‐rGO/CNTs‐COOH for the Detection of H2O2

AbstractNanocomposite enzymes are attracting intensive attention worldwide. In the present study, a novel colorimetric H2O2 paper sensor was developed based on a new type of nanocomposites composed of Pd−Pt nanoparticles, hemin functionalized reduced graphene oxide (hemin‐rGO) and carboxylated carbon nanotubes (CNTs‐COOH). The proposed nanocomposites show a high peroxidase‐like activity. It provides a sensitive platform showing a linear response toward H2O2 in the range of 0.05–500 μM with a determination limit of 0.01 μM. Based on this, the composites were applied to construct a paper sensor for H2O2 detection in real samples. The cost‐effectiveness, simplicity and efficiency of this paper sensor could be developed for “point‐of‐care” analysis and other related areas.

Electrochemical sensor based on carboxylated carbon nanotubes and chromium black T for the detection of ethyl maltol

In this paper, a novel electrochemical sensor based on carboxylated multi-walled carbon nanotubes (C-MWCNTs) and chromium black T (EBT) composites modified electrodes (EBT/C-MWCNTs/GCE) were proposed for the sensitive determination of ethyl maltol (EMA). Cyclic voltammetry and differential pulse voltammetry techniques were used to investigate the performance of EMA on EBT/C-MWCNTs/GCE. The results showed that the peak current of EMA was significantly enhanced by the EBT/C-MWCNTs/GCE compared with the bare glassy carbon electrode. The peak current showed a good linear relationship with the mass concentration of EMA in the range of 10 ∼ 1000 μg/L and the detection limit is 3.3 μg/L. Moreover, the sensor is easy to prepare and shows long term stability, which has great potential application for the determination of EMA in edible oil.

High-performance, thermal management and long-term preservation Epoxy/TPEDA -Fe3O4@ carboxylic carbon nanotube electromagnetic shielding composites

In this work, a high-performance electromagnetic interference (EMI) latent curing epoxy composites with combination of modified Fe3O4 and carboxylic carbon nanotube (CNTs) were prepared by magnetic orientation. The unique heterogeneous interface among magnetic nanoparticles and conductive nanowires facilitates the loss of interface polarization, the wave absorbance and the dipole polarization, makes EMI SET of the material reach respectively 45.86 dB in X-band at the thickness of 2 mm ± 0.1 mm, significantly exceeding that of other epoxy-based shielding materials. In addition, the composites show excellent thermal capacity reaching 1.59 W/m·K. What's more, the oriented epoxy mixture can be preserved at room temperature for 40 days maintaining a low viscosity state without curing, which has a strong practical application prospect in the field of electronic packaging materials.