Modified Carbon Nanotubes Research Articles

Preparation and Performance of Carbon Nanotube Modified Cement-Based Phase Change Material in Steel Bridge Engineering

Carbon nanotubes have excellent mechanical, electrical and chemical stability, and they are an excellent filler for the development of high-performance, multifunctional/smart cement-based composite materials. In order to understand the preparation and performance of carbon nanotubes modified cement-based, this paper studies the effects of carbon nanotube types and content on the mechanical, electrical, and electromagnetic wave shielding/absorption properties of cement-based materials. The product phase (morphology, composition, structure and content), composite material equivalent circuit and electromagnetic parameter analysis, and fiber-reinforced cement-based composite material mechanical calculations explore the modification mechanism of carbon nanotube cement-based materials. The experimental results found that when the amount of carbon nanotube modified cement is 0–3%, the flexural strength shows an upward trend. At 3–12%, the flexural strength gradually decreases, but in the range of 3–6%. From time to time, although the flexural strength is decreasing, after the final decrease, the strength is still greater than that of the traditional cement-based composite mortar. This shows that carbon nanotubes modified cement-based phase change materials can play an important role in steel bridge engineering.

Electrochemical Properties of the Composites Based on Multiwall Carbon Nanotubes Modified with Nanoparticles of Mixed Cobalt and Nickel Hydroxides

A simple and reproducible method of chemical deposition was used to modify carbon nanotubes cobalt and nickel hydroxides. Thus the composites containing 5 and 10 wt.% Co0.5Ni0.5(OH)2(the ratio of hydroxides1:1)were obtained based on the matrix of multiwall carbon nanotubes: non-functionalized (MWCNT) and functionalized (MWCNT-f). The physicochemical properties of the obtained nanocomposites were investigated with a focus on the characteristics that are relevant for use as the electrode materials of supercapacitors. Electrical capacity characteristics (specific electrical capacitance, internal resistance, etc.) of nanocomposites were determined using cyclic voltammetry and impedancemetry. The effect of matrix functionalization and filler content on the electrochemical characteristics of the composites was considered. It is established that the surface of carbon nanotubes allows the accumulation of the charge in the electrical double layer, in particular at high polarization rates. At low rates, the contribution from the pseudo-capacity component increases on the filler nanoparticles, on the surface of channels in nanotubes, and pore surface in hydroxide aggregates. An increase in the specific electrical capacitance of the composites by a factor of 1.5 to the capacitance of MWCNTs was achieved. The schemes of electrode processes in the nanocomposite are proposed, and the nature of redox peaks on voltammetric curves providing the occurrence of the pseudo-capacity component is revealed. Relying on the analysis of impedancemetry results, the equivalent series resistance and the charge transfer resistance are evaluated. An equivalent circuit of the cell with the working composite electrode is proposed, and its major parameters are calculated.

Covalent organic framework modified carbon nanotubes for removal of uranium (VI) from mining wastewater

The wastewater containing uranium produced in the mining process is harmful to the environment and life safety due to the inherent biotoxicity and radioactivity of uranium. In this paper, 4,4′-diamino-[1,1′-biphenyl]-3,3′-diol and 2,4,6-triformylphloroglucinol were in situ synthesized β-ketoenamine covalent organic frameworks (COFs) on the surface of carbon nanotubes (CNTs) to obtain a composite of CNT/COF-OH for removal uranium in the rare earth tailings wastewater. Grafting COFs with a large number of specific uranium-binding groups and redox-active sites on the surface of CNTs, CNT/COF-OH can effectively enhance the uranium ion selectivity and adsorption capacity. Furthermore, CNTs have good electron transport capacity and π-conjugation properties, electrons can be effectively transferred from CNTs to COFs, which increases the electron density of the adsorption functional groups, resulting in an increase of the adsorption energy and reductive activity for U (VI), thus improving the removal efficiency. In addition, the skeleton of COFs can be supported by CNTs, thus reducing collapse. Through the synergistic effect of composite, CNT/COF-OH had a good uranium adsorption capacity of 518.2 mg g−1. The adsorption capacity of CNT/COF-OH was increased by 390.7 %, 54.6 %, and 84.5 % compared with those of single CNTs, COF-OH, and mixed CNT + COF-OH, respectively. The selective separation coefficient of CNT/COF-OH was 1.6 times higher than that of COF-OH. The experiment of uranium removal was carried out in the rare earth tailings wastewater using CNT/COF-OH, the removal rate reached 96.7 %. The COFs modified CNTs with synergistic effect have important theoretical and practical significance for the safety problems caused by harmful ions in wastewater.

Tunable mechanical, self-healing hydrogels driven by sodium alginate and modified carbon nanotubes for health monitoring

Conductive hydrogels featuring a modulus similar to the skin have flourished in health monitoring and human-machine interface systems. However, developing conductive hydrogels with self-healing and tunable force-electrical performance remains a problem. Herein, a hydrogen bonding cross-linking strategy was utilized by incorporating silk sericin-modified carbon nanotubes (SS@CNTs) into sodium alginate (SA) and polyvinyl alcohol (PVA). Hydrogels synthesized with desirable tensile strength and self-healing ability (67.2 % self-healing efficiency in fracture strength) assembled into strain sensors with a low detection limit of 0.5 % and a gauge factor (GF) of 4.75 (0–17 %). Additionally, as-prepared hydrogels exhibit high sensitivity to tiny pressure changes, allowing recognition of complex handwriting. Notably, resulting hydrogels possess self-powered property, generating up to 215 V and illuminating 100 commercial green LEDs. This work stems from the pressing need for multifunctional hydrogels with prospective applications in human motion sensing and energy harvesting.

(Invited) DNA-Controlled Carbon Nanotube Functionalization

In this talk, I will present our work on DNA-controlled functionalization of single-chirality carbon nanotubes, using the photochemical Guanine oxidation reaction first reported by the Weisman group (ACS Nano, 2019, 13, 8222). By employing resonance Raman and fluorescence spectroscopy, we are able to reveal strong sequence-dependent modification of carbon nanotubes. We have also used cryo-EM to characterize the reaction product. Our results provide new insight into the reaction mechanism.

One-pot synthesis of superhydrophobic photothermal materials with self-healing for efficient ice removal

Solar energy-facilitated materials are promising to solve energy loss problems for anti-icing/deicing applications by conversion clean solar energy to thermal energy. However, the photothermal conversion performance seriously affect by dirt and liquid contaminants. Moreover, melted ice may wet photothermal materials and freeze again. Herein, durable superhydrophobic photothermal coatings were designed by modifying carbon nanotubes with dodecylamine (DDA) and dopamine via Michael addition reaction. Thanks to the photothermal synergistic effect of PDA and CNTs, the surface temperature of obtain coating rapidly rose to 89.8 °C under 1 kW/m2. Besides, hierarchical structure and low surface energy alkyl long chain of the coating provided excellent self-cleaning property (CA = 162.5 ± 0.9°), which can avoid the adhesion of contaminants and extend the freezing time of ice for anti-icing. Furthermore, the ice quickly melted and rolled off immediately after irradiation, which avoids refreezing again. Thus, the prepared coating maintained sustainable photothermal conversion for effective deicing performance. Besides, the prepared coating possessed mechanical durability, excellent corrosion protection and even kept self-cleaning ability at 400 °C. More importantly, the coating shows excellent self-healing property toward both mechanical and chemical damage. The outstanding environmental adaptability can greatly extend its lifespan and meet the long-term service conditions.

Influence of nanocomposite preparation techniques on the multifunctional properties of carbon fabric‐reinforced polystyrene‐based composites with carbon nanotubes

AbstractPolystyrene (PS)‐based and carbon fabric‐reinforced polymers (CFRPs) containing elastomer were prepared using the compression molding technique. PS was also reinforced with two types of carbon nanotubes (CNTs), as received and modified with a silane‐coupling agent. Nanocomposites were fabricated with two different methods, masterbatch dilution, and direct melt mixing. The effect of the nanocomposite preparation technique on the mechanical properties, electrical resistivity, and shape memory behavior of the multilayer composites was investigated. The tensile strength and tensile modulus of the multilayer composite containing CNTs modified with silane coupling agent, and prepared with masterbatch dilution method, increased by 33% and 34%, respectively, compared with the composites prepared with melt mixing. With the masterbatch dilution technique, the electrical resistivity was lower, and slightly increased with surface modification of CNTs. In both preparation techniques, the possible combined effect of CNTs and CF on the thermal and electrical conductivity of the composites led to 100% shape recovery lower than 30 s with electrically actuated bending test.

Highly Sensitive Determination of Niclosamide Based on The Graphitized and Carboxylated Multi-Walled Carbon Nanotubes Modified Glassy Carbon Electrode

Highly Sensitive Determination of Niclosamide Based on The Graphitized and Carboxylated Multi-Walled Carbon Nanotubes Modified Glassy Carbon Electrode

Multi–walled Carbon Nanotubes Modified Stainless Steel Fiber Felt Supported on Cobalt Electrode for N2H4 Electrooxidation in Alkaline Solution

Multi–walled Carbon Nanotubes Modified Stainless Steel Fiber Felt Supported on Cobalt Electrode for N2H4 Electrooxidation in Alkaline Solution

Surface Modification of Multi-Walled Carbon Nanotubes with Polysaccharides

Multi-walled carbon nanotubes (MWCNTs) are known as efficient drug carriers. To improve their interaction with other materials, surface modification of MWCNTs is necessary. In this work, MWCNTs were functionalized with acid and polysaccharides (chitosan and gelatin). The functionalization process was done via modification with acid solutions of nitric acid, sulfuric acid, and a mixture of nitric acid-sulfuric acid first, followed by functionalization with chitosan and gelatin. To achieve the optimum condition of MWCNTs functionalization, the reaction time, temperature, and acid ratio were varied. Furthermore, the effect of chitosan and gelatin addition into MWCNTs was studied at various mass ratios. The synthesized materials were characterized by Fourier transform infrared spectrophotometer, Boehm titration, and dispersion test. The Boehm titration results showed that the acid functional groups had been attached successfully to MWCNTs surface. The amount of acid functional groups increased along with reaction time. The highest amount of acidic group obtained from the data was 2.33 mmol/g. It was achieved when MWCNTs reacted with nitric acid for 24 hours. Temperature and acid ratio variations on the MWCNTs functionalization did not provide significant results. From the FTIR data, sharp peaks at 3480 cm-1 and 1040 cm-1 indicates a -CONH bond, which shows that chitosan and gelatin have been successfully grafted onto MWCNTs surface via an amide linkage. Moreover, the dispersion test showed that the functionalized materials were stable for 48 hours.

Effect of Surface Modification of Carbon Nanotubes on the Properties of High-Strength and High-Conductivity Copper Matrix Composites

The use of carbon nanotubes (CNTs) as the reinforcing phase to prepare copper-based composite materials can improve the strength and high conductivity of copper-based conductors. In order to analyze the effect of surface oxidation modification on the structural properties of carbon nanotubes and its strengthening effect on composite materials, this article combines heterogeneous copolymerization liquid phase mixing method and spark plasma sintering molding method; prepares the carbon nanotubes/copper composite materials using carbon nanotubes under different oxidation treatment conditions as the reinforcing phase (the volume fraction of carbon nanotubes is 3%); and characterizes the microstructure, mechanical properties, and electrical and thermal conductivity of the composite material. Studies have shown that the tensile strength and hardness of composite materials first increase with the increase of CNT oxidation treatment time and then decrease with the increase of oxidation treatment time. When the oxidation treatment time is 4 h, CNTs are uniformly dispersed in the matrix while maintaining good structural integrity and load-bearing capacity, and the composite material has the highest mechanical properties. The tensile strength of the composite material made of 80‐ nm CNTs reaches 452.4 MPa, which is 1.6 times that of pure copper, and the hardness reaches 127.4HV, which is twice that of pure copper. The electrical conductivity and thermal conductivity of the composite material first increase with the increase of the oxidation treatment time of carbon nanotubes and then decrease with the increase of the oxidation treatment time. The 80 nm CNT reinforced composite material has better CNT dispersion performance and higher conductivity than that of 15 nm CNT preparation. The electrical conductivity of the composite material reaches the maximum value of 92% IACS when the CNT oxidation treatment time is 4 hours, which is 95% of the pure copper sample, and the electrical conductivity is significantly better than that of the CNT/Cu composite material and copper alloy prepared by other methods. The thermal conductivity of composite materials is lower than that of pure copper. The thermal conductivity of carbon nanotubes with an oxidation treatment time of 2 h decreases most obviously, indicating that the thermal resistance generated by the interface and agglomeration phases in the composite material affects its thermal conductivity.

Preparation, Characterization, and Application of (MWCNTs)-COOH/Eu2O3 as an Efficient Reusable Catalyst

Modification of acid-functionalized multi-walled carbon nanotubes (MWCNTs)-COOH with Eu2O3 nanoparticles using Eu(NO3)3.6H2O, produced an efficient catalyst for the synthesis of some nitrogen-containing heterocycles such as quinoxalines. The products were identified by CHN analysis, NMR, and FT-IR spectra. On the other hand, synthesis of Eu2O3 nanoparticles and their conjugation on the surface of (MWCNTs)-COOH have been confirmed by FT-IR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX).

Spectrophotometric determination of chlorpyrifos in foodstuff after pipette-tip micro solid extraction by modified carbon nanotube

In this study, polypropylene-based carbon nanotubes (CNTs/PPy) were prepared and employed as a novel sorbent for pipette tip micro-solid phase extraction of chlorpyrifos from foodstuff samples followed by its spectrophotometric determination. Various parameters that can effect on analytical extraction (type and volume of eluent, mass of CNTs/PPy, pH and volume of sample solution, and extraction and elution cycles number) were studied and optimized by using one-variable-at-a-time procedure, central composite design (CCD) and Box-Behnken design (BBD) and results were compared. Among them, BBD showed the best performance. For BBD and CCD, experimental design was employed with four variables in three levels. The linear range under optimum conditions for the analyte was 1–1000 µg L−1 by a limit of detection of 0.17 µg L−1. The suggested protocol has been successfully employed for the determination of chlorpyrifos in tomato, cucumber and fish samples.

Electrochemical Biosensor for Rapid Detection of Listeria monocytogenes

Listeria monocytogenes (L. monocytogenes) is a common foodborne pathogen that has been responsible for many foodborne illness outbreaks in recent years. Currently, Listeria contamination in food products is identified only through molecular tests conducted in diagnostic laboratories. No established phage based diagnostic methods for L. monocytogenes during food production or processing are used. Here we report a potentially disruptive rapid diagnostic method based on electrochemical biosensing principles that use bacteriophages as bioreceptors for selective identification and quantification of L. monocytogenes. Electrochemical biosensors are good alternatives to molecular detection methods due to their ease of use, high specificity, sensitivity, and low cost. Bacteriophages can serve as excellent biorecognition elements in biosensors due to their robust stability in a range of environmental conditions and their ability to distinguish between live and dead bacterial cells. The impedimetric biosensing platform for L. monocytogenes detection was developed by immobilizing P100 bacteriophage onto quarternized polyethylenimine modified carbon nanotubes using an in-house developed molecular tethering method. The resulting sensor showed high selectivity and sensitivity toward L. monocytogenes with a limit of detection of 8.4 CFU/ml. Initial results demonstrate that the biosensing platform is highly reliable in its selectivity towards its target analyte, L. monocytogenes.

Study on preparation and field induction mechanism of organic silicon composites based on aligned carbon nanotubes

AbstractHigh thermal conductivity materials are an urgent need for high power, microelectronic components and equipment, but are limited by low thermal conductivity of the traditional silicone materials. 4‐Cyano‐4′‐n‐octyl biphenyl (8OCB) was synthesized to modify carbon nanotubes, and silicone was used as the matrix. In the curing process of the composite, an electric field was applied and the liquid crystal induced the orientation of carbon nanotubes in the direction of 8OCB liquid crystal. The morphology, structure and properties of modified carbon nanotubes and composites were characterized by Fourier transform infrared spectroscopy, polarized microscopy, transmission electron microscopy, thermal conductivity, and so on. The 8OCB liquid crystal can improve the dispersion of carbon nanotubes in silicone composites. When the mass fraction of multiwalled carbon nanotubes (MWCNTs) was 11 wt%, the thermal conductivity of 8OCB‐MWCNTs/silicone composite after electric field was 2.39 W/(m K), which is 6.4 times that of MWCNTs/silicone composite after electric field and 15.5 times that of pure silicone matrix. A method to obtain highly ordered filled thermal conductive materials by applying an electric field to induce the orientation of carbon nanotubes is demonstrated.

Preparation, characterization, and adsorption properties of modified carbon nanotubes for highly effective removal of tetracycline from aquaculture wastewater

AbstractIn this study, the adsorption of the antibiotic compound tetracycline (TC) from aquaculture wastewater was investigated using lanthanum‐modified carbon nanotubes (La‐CNTs) prepared by impregnation method. The composition and morphology of La‐CNTs were characterized by EDS, XRD, and BET analysis. Single‐factor experiments were performed to investigate their effect on the adsorption of TC by La‐CNTs. The adsorption kinetics and adsorption isotherms indicated that the pseudo‐second‐order kinetic model and Langmuir adsorption isotherm equation adequately described the adsorption behavior of La‐CNTs. Moreover, the maximum adsorption capacity () was 93.46 mg/g. The thermodynamics studies indicated that adsorption of TC by La‐CNTs were endothermic and spontaneous respectively. Further, the adsorption force of La‐CNTs on TC could be attributed to van der Waals force, π–π adsorbate–adsorbent interaction and electrostatic interaction. Based on these experimental results, this novel composite material shows good potential application value for the removal of TC from aquaculture wastewater.

An abrasion-resistant, photothermal, superhydrophobic anti-icing coating prepared by polysiloxane-modified carbon nanotubes and fluorine-silicone resin

Hydrophobic modification of carbon nanotubes was performed using poly(methyl-3,3,3-trifluoropropyl siloxane) (PMTFPS). Then a superhydrophobic anti-icing coating with photothermal effect was successfully prepared by using fluorine-silicone resin as a binder and building a micro-nano structure using hydrophobic carbon nanotubes. The coating has good hydrophobic properties with a contact angle of 160.8° and a sliding angle of 2°. The performance of the coating was also evaluated by sandpaper abrasion test, complete freezing time, ice adhesion strength, and infrared irradiation. The coating maintained good hydrophobicity even after 100 cycles of abrasion or after being immersed for 12 h in solutions with different conditions. The good abrasion resistance and chemical durability of the coating in aqueous solutions were demonstrated. The complete freezing time of 10 µl water droplet on the coating surface was prolonged by 11.6 times at − 15 °C. The ice adhesion strength of the coating was only 33.3 kPa, which was 92.1% lower than that of the tinplate. After 50 de-icing cycles, the ice adhesion strength on the coating was still relatively stable. The coating had significant photothermal properties, with the temperature rising 14.3 °C after 1 min irradiation by a 150 W infrared light.

The Influence of Physical Activation of Portland Cement in the Electromagnetic Vortex Layer on the Structure Formation of Cement Stone: The Effect of Extended Storage Period and Carbon Nanotubes Modification

The article presents research of the influence of the electromagnetic vortex layer on the structure formation of cement stone during the activation of portland cement, both without additives and with carbon nanotubes modification. It has been shown that the storage of portland cement powders in open air for 60 days after activation in the electromagnetic mill leads to partial carbonization, wherein the role in absorption reducing of the super plasticizer additive is increased since there is more uniformly localization of the additive on the surface of the portland cement particles. The processing of portland cement in the electromagnetic mill leads to the physical activation of portland cement, which is accompanied by an increase in the amount of heat generated by the hydration of portland cement and the rate of hydration. Thus, the rate of hydration of compositions activated in the electromagnetic mill isincreased 1.615 times at the temperature of the thermostat 22 °C; 1.85 times at 40 °C; 2.71 times at 60 °C; 2.3 times at 80 °C. The modification of cement stonewith carbon nanotubes, which was obtained from portland cement activated in an electromagnetic mill, leads to a higher quantity of silicate phase of portland cement (by 12–39%), as confirmed by a decrease in the number of portlandite in these compositions by 8% in comparison with control composition.

Theoretical and experimental study on the fluidity performance of hard-to-fluidize carbon nanotubes-based CO2 capture sorbents

Carbon nanotubes-based materials have been identified as promising sorbents for efficient CO2 capture in fluidized beds, suffering from insufficient contact with CO2 for the high-level CO2 capture capacity. This study focuses on promoting the fluidizability of hard-to-fluidize pure and synthesized silica-coated amine-functionalized carbon nanotubes. The novel synthesized sorbent presents a superior sorption capacity of about 25 times higher than pure carbon nanotubes during 5 consecutive adsorption/regeneration cycles. The low-cost fluidizable-SiO2 nanoparticles are used as assistant material to improve the fluidity of carbon nanotubes-based sorbents. Results reveal that a minimum amount of 7.5 and 5 wt% SiO2 nanoparticles are required to achieve an agglomerate particulate fluidization behavior for pure and synthesized carbon nanotubes, respectively. Pure carbon nanotubes + 7.5 wt% SiO2 and synthesized carbon nanotubes + 5 wt% SiO2 indicates an agglomerate particulate fluidization characteristic, including the high-level bed expansion ratio, low minimum fluidization velocity (1.5 and 1.6 cms−1), high Richardson—Zaki n index (5.2 and 5.3 > 5), and low Π value (83.2 and 84.8 < 100, respectively). Chemical modification of carbon nanotubes causes not only enhanced CO2 uptake capacity but also decreases the required amount of silica additive to reach a homogeneous fluidization behavior for synthesized carbon nanotubes sorbent.

Electrochemical Determination of Riboflavin using a Poly(Titan Yellow) Modified Carbon Nanotube Paste Electrode in the Presence of Dopamine

AbstractThe bare carbon nanotube paste electrode (BCNTPE) is a helpful base material for the construction of different electrometric sensors for analytical purposes. The BCNTPE was chemically modified with a polymerization process using titan yellow (TY) dye for the selective determination of riboflavin (RF) in presence of dopamine (DA). A poly(titan yellow) modified carbon nanotubes paste electrode (PTYMCNTPE) has been constructed by a simple and eco‐friendly procedure. The PTYMCNTPE material surface was examined by cyclic voltammetry (CV), Field emission‐scanning electron microscopy (FE‐SEM), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) methods. The outcomes suggested that the modified electrode displays high electrocatalytic action for the redox reaction of RF. The limit of detection (LOD) and limit of quantification (LOQ) for the detection of RF were found to be 2.679×10−8 M and 8.932×10−8 M, correspondingly. The proposed sensor was effectively applied for the determination of RF in a pharmaceutical sample.