Surface Of Carbon Nanotubes Research Articles

Theoretical study of the relationship between the electronic structure of carbon nanotube surface and its hydrogenation sites

The activation energy of radical addition to polycyclic aromatic carbons consisting of only six-membered rings decreases with increasing curvature. In this study, the position of monohydrogenation in carbon nanotubes containing five- and six-membered carbon rings was investigated through density functional theory calculations. The activation energies of the monohydrogenation of carbon at the intersection of three six-membered rings were 2.0–2.8 kcal mol−1, and those of carbon-containing one five-membered ring were close to zero. Bonding sites involving a five-membered ring were found to have lower deformation energies for becoming sp3-like, and induced stronger interactions with hydrogen atoms.

Synthesis, characterization, and electrochemical evaluation of SnFe2O4@MWCNTS nanocomposite as a potential hydrogen storage material

The widespread use of hydrogen as a vehicle fuel has prompted us to develop a new nanocomposite by immobilizing of tin ferrite nanoparticles (SnFe2O4) on the surface of multi-walled carbon nanotubes (abbreviated as MWCNTS) for the first time. The prepared nanocomposite powder (SnFe2O4@MWCNTS) was investigated utilizing various microscopy and spectroscopy methods, such as FT-IR, XRD, SEM, EDX, and BET techniques. Moreover, the electrochemical property of SnFe2O4@MWCNTS nanocomposite was investigated by cyclic voltammogram (CV) and charge–discharge chronopotentiometry (CHP) techniques. A variety of factors on the hydrogen storage capacity, such as current density, surface area of the copper foam, and the influence of repeated hydrogen adsorption-desorption cycles were assessed. The electrochemical results indicated that the SnFe2O4@MWCNTS has high capability and excellent reversibility compared to SnFe2O4 nanoparticles (NPs) for hydrogen storage. The highest hydrogen discharge capability of SnFe2O4@MWCNTs was achieved ∼ 365 mAh/g during the 1st cycle, and the storage capacity enhanced to ∼ 2350 mAh/g at the end of 20 cycles using a current of 2 mA. Consequently, the SnFe2O4@MWCNTS illustrated great capacity as a prospective active material for hydrogen storage systems.

High-Strength Epoxy Nanocomposites Reinforced with Photochemically Treated CNTs.

A carbon nanotube (CNT)/epoxy nanocomposite was prepared using a photochemical surface modification process of CNTs. The vacuum ultraviolet (VUV)-excimer lamp treatment created reactive sites on the CNT surface. Increasing the irradiation time increased the oxygen functional groups and changed the oxygen bonding state such as C=O, C-O, and -COOH. By the VUV-excimer irradiation on CNTs, the epoxy infiltrated well between the CNT bundles and formed a strong chemical bond between CNT and epoxy. The tensile strength and elastic modulus of the nanocomposites with VUV-excimer irradiated sample during 30 min (R30) were found to increase by 30 and 68% compared to using pristine CNT, respectively. R30 was not pulled out and remained embedded in the matrix until the fracture occurred. The VUV-excimer irradiation is an effective surface modification and functionalization method for improving the mechanical properties of CNT nanocomposite materials.

Confining NiCo2O4 nanoparticles in nitrogen doped carbon nanotubes embedded in 3D porous graphene aerogels for superior lithium storage

The huge volume expansion and poor electrical conductivity have seriously hindered the further development of redox-based electrode materials such as NiCo2O4 (NCO). Herein, we designed a novel NiCo2O4@nitrogen-doped carbon nanotube@3D graphene (NCO@CT@3DG) aerogel through hydrothermal assembly and high-temperature carbonization. In this aerogel, graphene nanosheets constructed the framework of the aerogel and NCO nanoparticles were deposited on the surface of nitrogen-doped carbon nanotubes which served as active materials for Lithium-ion batteries. The NCO decorated carbon nanotubes connecting the graphene sheets served as the scaffold to support the 3D cross-linked graphene network. As anode material of lithium-ion batteries, the optimized NCO@CT@3DG exhibited excellent electrochemical properties with high capacity as well as superior cycle and rate performance, which could maintain the discharge specific capacity of 810.3 mAh/g at the current density of 1.0 A/g after 500 cycles. The excellent properties are ascribed to the synergistic effect of each individual component and the unique graphene aerogels hybrid structure. This study demonstrates the great application prospects of 3DG aerogel hybrid structure in improving electrochemical properties of active materials with high volume expansion and poor conductivity.

Design and synthesis of C@MoSe2@NMWCNT heterostructure as anode material for Na+ batteries via Mo-based organic complexes

Theoretically, molybdenum selenide (MoSe2) has the characteristic of high storage capacity for sodium ions, but it shows poor rate performance and cycle stability in actual sodium storage experiments. Additionally, heteroatom doping is beneficial to the high electronic performance of carbon materials. For example, the addition of nitrogen (N) to carbon nanotubes (CNT) leads to additional electrons on the surface of CNT, thus enhancing CNT conductivity. Herein, employing N-doped multi-wall CNT (NMWCNT), we synthesized C@MoSe2@NMWCNT nanocomposites that are endowed with heterojunctions. The results of DFT calculation suggest that the electron transfer intensity between the interfaces of C@MoSe2@NSWCNT (SW stands for single-wall) is obviously higher than that of C@MoSe2@SWCNT, and NSWCNT plays a role in promoting the electron transfer. In addition, the combination of MoSe2 with SWCNT can effectively reduce the Na+ diffusion energy barrier between MoSe2 layers in the C@MoSe2@NSWCNT composite (lowered from 0.91 to 0.69 eV), hence promoting Na+ mobility, and thus improving the performance of the system for Na+ storage. Experimentally, the PEG-200-2-C@MoSe2@NMWCNT system exhibited capacity of 226 mA h g−1 after 1100 cycles and 168 mA h 01 after 3600 cycles at a current density of 2 A g−1. Under the synergistic effect of carbon coating and NMW`CNT network, the stability of the Na+ storage of MoSe2 is significantly improved. This work can shed light for the research of nitrogen doped carbon-based materials.

Carbon nanotubes grafted by polyurethane chains with dopamine-mediation to enhance the mechanical and damping properties of polyurethane elastomer

A novel strategy of combining mussel inspired dopamine chemistry and polycondensation reactions to construct unique functionalized carbon nanotubes (CNTs) with polyurethane (PU) chains was demonstrated. The polydopamine (PDA) was firstly functionalized to the surface of carbon nanotubes, then polydopamine acted as a bridge and covalently reacted with polyurethane chains to form a network structure named CNTs-PDA-PU, which improved the ability of polyurethane chains grafted onto carbon nanotubes. The functionalized carbon nanotubes significantly enhanced the mechanical and damping properties of nanocomposites. It was found that the highest mechanical properties were achieved at 0.1% loading of CNTs-PDA-PU, leading to the tensile strength and elongation at break increased by 97% and 25%, respectively, compared with matrix. More interestingly, the functionalized carbon nanotubes could form multiple physical and chemical interface interactions with matrix, thus alter the microphase separation structure of nanocomposites. This novel carbon nanotubes functionalization and elastomer synthesis method can provide ideas for the application of nanocomposites.

What's New in Musculoskeletal Infection.

What's New in Musculoskeletal Infection.

Graphene Oxide/Styrene-Butadiene Latex Hybrid Aerogel with Improved Mechanical Properties by PEI Grafted GO and CNT.

Graphene oxide aerogel (GOA) has wide application prospects due to its low density and high porosity. However, the poor mechanical properties and unstable structure of GOA have limited its practical applications. In this study, polyethyleneimide (PEI) was used to graft onto the surface of GO and carbon nanotubes (CNTs) to improve compatibility with polymers. Composite GOA was prepared by adding styrene-butadiene latex (SBL) to the modified GO and CNTs. The synergistic effect of PEI and SBL, resulted in an aerogel with excellent mechanical properties, compressive resistance, and structural stability. When the ratio of SBL to GO and GO to CNTs was 2:1 and 7:3, respectively, the obtained aerogel performance was the best, and the maximum compressive stress was 784.35% higher than that of GOA. The graft of PEI on the surface of GO and CNT could improve the mechanical properties of the aerogel, with greater improvements observed with grafting onto the surface of GO. Compared with GO/CNT/SBL aerogel without PEI grafting, the maximum stress of GO/CNT-PEI/SBL aerogel increased by 5.57%, that of GO-PEI/CNT/SBL aerogel increased by 20.25%, and that of GO-PEI/CNT-PEI/SBL aerogel increased by 28.99%. This work not only provided a possibility for the practical application of aerogel, but also steered the research of GOA in a new direction.

Functionalization of Carbon Nanotubes Surface by Aryl Groups: A Review.

The review is devoted to the methods of introducing aryl functional groups to the CNT surface. Arylated nanotubes are characterized by extended solubility, and are widely used in photoelectronics, semiconductor technology, and bioelectrocatalysis. The main emphasis is on arylation methods according to the radical mechanism, such as the Gomberg-Bachmann and Billups reactions, and the decomposition of peroxides. At the same time, less common approaches are also considered. For each of the described reactions, a mechanism is presented in the context of the effect on the properties of functionalized nanotubes and their application. As a result, this will allow us to choose the optimal modification method for specific practical tasks.

Effect of carbon nanotube substrate temperature on the evolution mechanism of microstructure in FeCoNiCrCu coatings

The microstructure and substrate temperature dependence of FeCoNiCrCu high-entropy alloys (HEAs) coatings on carbon nanotube (CNT) surfaces were investigated using experimental and molecular dynamics simulations. It was found that the crystal structure of FeCoNiCrCu underwent the evolution of amorphous, stacking faults (SFs), multiple-fold twins, and columnar grains with an increase in the CNT substrate temperature. When the CNT substrate temperature was less than 800 K, the SFs and microtwin formation was induced by the mismatch stress at the interface of HEAs and CNT. Meanwhile, the refinement of SFs was caused by continuous crossing and cutting of dislocations. When the CNT substrate temperature was greater than 800 K, multiple-fold twin were induced by thermal stress at the surface of HEAs coating. During the evolution of the fivefold twin, the first microtwin was formed from the surface of the HEAs, and the remaining four microtwin growth from the center successively. These results provide a new method to design and control the interface structure between HEAs and CNTs.

Two-Dimensional Polyphosphazene Nanosheet-Derived N,P Doubly Doped Carbon Nanotubes for Electrocatalytic Oxygen Reduction

Two-dimensional (2D) covalent organic polymers (COPs) featuring large surface areas and exposed active sites are desirable in the modification of electrode materials for electrochemical reactions. However, the rigid and planar conformation of 2D COPs limits the wrap of one-dimensional electrodes. Herein, we have proposed a molecular strategy to regulate in situ encapsulation of carbon nanotubes (CNTs) with 2D polyphosphazene. The stoichiometric control over the nucleophilic substitution reaction between hexachlorocyclophosphazene and amines allows for the oriented evolution around the surface of CNTs. The formed COP sheath is an ultrathin and uniform coating without granular deposition. Upon carbonization, the well-defined core/shell CNT composite was converted into the N,P-codoped carbon, exhibiting outstanding electrocatalytic oxygen reduction performance with a diffusion-limiting current density of 5.4 mA cm–2 and an electron transfer number of 3.97. The improved electrocatalytic activity originates from a high content of active N,P-containing catalytic sites uniformly distributed on porous carbon. This study provides a viable strategy to develop functional composite materials by modulating the flexibility of 2D COPs for 1D substrates, contributing to broad applicability.

Research Progress on Microstructure Design of CNTs Reinforced Al Matrix Composites

Carbon nanotubes (CNTs) have unique characteristics which make them a suitable reinforcing agent in Aluminum Metal Matrix composites. This review summarizes the work carried out in the field of the microstructure design of CNTs/Al composites. By designing the microstructure of CNTs, Al matrix and their composite interface, the problems of agglomeration, entanglement and dispersion of CNTs, wetting and bonding with Al matrix can be effectively solved, and mechanical properties such as Young’s modulus and yield strength can be improved. Such microstructural design includes metal plating on the surface of CNTs, deposition of nano-ceramic particles, Al matrix ball milling and flakes, grain refinement combined with bimodal-grain strengthening of coarse grains.

Developing a dual-functional self-healing nanocomposite utilizing oxidized-multiwall carbon nanotube/highly-porous metal-organic framework (OCNT/ZIF-8) nano-hybrid

In this study, an anticorrosion epoxy (EP) coating based on a nano-hybrid filler of multi-walled carbon nanotubes, and a metal-organic framework (MOF) with mixed active/barrier anticorrosion performance were developed. The nano-hybrid was derived by growing ZIF-8 nanoparticles on an oxidized-multiwall carbon nanotube (OCNT) surface using two distinct synthesis methods, hydrothermal and coprecipitation, denoted as OCNTZ-I and OCNTZ-II, respectively. Different characterization methods proved the successful modification of OCNT structures with ZIF-8 nano-particles. Furthermore, ICP tests confirmed that Zn cations were released more in an acidic medium, showing that the synthesized particles have pH-responsive properties. After the incorporation of the nano-hybrids into EPs, the effectiveness of the nano-hybrids as anticorrosion materials and the effects of the synthesis procedure on nanocomposites performance were examined. EIS measurements, microscopic analyses, and salt spray tests indicated considerable improvements in the active/barrier anticorrosion properties of the nanocomposite EP coatings. After eight weeks of immersion in a saline solution, the OCNTZ-I/EP and OCNTZ-II/EP intact coatings exhibited a high impedance modulus of |Z|10 mHz (over 109 Ω·cm2), which was significantly higher than the control EP. Moreover, following 24 h of immersion, the charge transfer resistance (Rct) of the scratched OCNTZ-I/EP and OCNTZ-II/EP coatings was approximately two and four times higher than the Rct value of the scratched control EP, respectively. Also, the assessments of the adhesion properties of the nanocomposite coatings revealed a significant improvement in adhesion stability. The adhesion loss of the control EP decreased from 86.67% to 38.35% and 41.71% for the OCNTZ-I/EP and OCNTZ-II/EP coatings.

Grafting of polyaniline onto polydopamine-wrapped carbon nanotubes to enhance corrosion protection properties of epoxy coating

Ordinary coatings can hardly meet the long-term corrosion protection requirements of modern industries. Incorporating high-performance fillers in these coatings is considered an effective way to solve this problem. In this work, the carbon nanotubes (CNTs) with polydopamine (PDA) modification was obtained by self-polymerization of dopamine on the surface of carbon nanotubes (CNTs), and then polyaniline (PANI) was grafted onto the surface of CNTs-PDA, and CNTs-PDA-PANI nanocomposites were successfully prepared. This novel strategy improves the dispersion of CNTs while increasing their surface active sites, which facilitates the uniform grafting of PANI onto the CNTs surface. Finally, the obtained nanocomposites were incorporated into epoxy resins (EP) to study their enhancement of epoxy coatings under both passive and active corrosion protection mechanisms. Electrochemical impedance spectroscopy (EIS) showed that the low-frequency impedance of CNTs-PDA-PANI/EP coating was still as high as 1.19 × 1010 Ωcm2 after 50 days of immersion in 3.5 wt% NaCl solution, which was about two orders of magnitude higher than that of the pure epoxy coating. The superior corrosion protection mechanism was attributed to the barrier of the nanofillers to the corrosive medium and the induction of the metal passivation film. Therefore, this nanocomposite construction strategy may have a high potential in the field of corrosion protection.

Computational Methods in the Drug Delivery of Carbon Nanocarriers onto Several Compounds in Sarraceniaceae Medicinal Plant as Monkeypox Therapy

In this article, monkeypox is studied as a zoonotic poxvirus disease which can occur in humans and other animals due to substitution of the amino acid serine with methionine. We investigate the (+)-catechin, betulinic acid, ursolic acid, quercetin-3-O-galactoside, luteolin-7-O-glucoside, and myricetin in Sarracenia purpurea drugs from Sarraceniaceae family for treating monkeypox disease. This is performed via adsorption onto the surface of (6,6) armchair single-walled carbon nanotube (SWCNT) at the B3LYP/6-311+G (2d,p) level of theory in a water medium as the drug delivery method at 300 K. Sarracenia purpurea has attracted much attention for use in the clinical treatment of monkeypox disease due to the adsorption of its effective compounds of (+)-catechin, betulinic acid, ursolic acid, quercetin-3-O-galactoside, luteolin-7-O-glucoside, and myricetin onto the surface of (6,6) armchair SWCNT, a process which introduces an efficient drug delivery system though NMR, IR and UV-VIS data analysis to the optimized structure. In addition to the lowering of the energy gap (∆E = E LUMO − EHOMO), HOMO–LUMO energy has illustrated the charge transfer interactions taking place within (+)-catechin, betulinic acid, ursolic acid, quercetin-3-O-galactoside, luteolin-7-O-glucoside, and myricetin. The atomic charges have provided the proper perception of molecular theory and the energies of fundamental molecular orbitals.

Preliminary Study on Electrodeposition of Copper Platings and Codeposition of Carbon Nanotubes from Organic Solvent

Metal/carbon composite plating is an effective strategy for improving and adding properties to metal plating by incorporating carbon materials into the metal matrices. Copper (Cu) is widely applied, particularly in the areas of heat management and electronic packaging owing to its high thermal and electrical conductivities, which can be further improved together with improvements in mechanical properties by compositing it with carbon nanotubes (CNTs). However, because hydrophobic CNTs are hardly dispersible in aqueous solutions, additional intense acid treatment or the addition of dispersants is required for their dispersion. Moreover, previous studies have reported that these methods suffer from deterioration of composite material performance through the destruction of the CNT surface or the inclusion of dispersants into the plating. Therefore, in this study, the electrodeposition of a Cu/CNT composite in a non-aqueous solvent that can disperse CNTs without any additional treatment is investigated. The experimental results show that it is possible to deposit Cu from a N-methyl-2-pyrrolidone containing copper iodide and potassium iodide. Furthermore, Cu/CNT composite platings containing CNTs up to 0.12 mass% were prepared by constant current electrolysis, and applying pulse electrolysis can increase the CNTs content up to 0.22 mass%.

Vapor-phase derived ultra-fine Bismuth nanoparticles embedded in carbon nanotube networks as anodes for sodium and potassium ion batteries

Bismuth (Bi) is a promising material as the anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its characteristics such as reasonable price and high theoretical volumetric capacity (3800 mAh cm−3). Nevertheless, considerable drawbacks have hindered the practical applications of Bi, including its relatively low electrical conductivity and inevitable volumetric change during the alloying/dealloying processes. To solve these problems, we proposed a novel design:Bi nanoparticles were synthesized via a single-step low-pressure vapor-phase reaction and embedded onto the surfaces of multi-walled carbon nanotubes (MWCNTs). After being vaporized at 650℃ and 10-5 Pa, Bi nanoparticles less than 10 nm were uniformly distributed in the three-dimensional (3D) MWCNT networks to form a Bi/MWNTs composite. In this unique design, the nanostructured Bi can reduce the risk of structural rupture during cycling, and the structure of the MWCMT network is beneficial in shortening the electron/ion transport path. In addition, MWCNTs can improve the overall conductivity of the Bi/MWCNTs composite and prevent particle aggregation, thus improving the cycling stability and rate performance. As an anode material for SIB, the Bi/MWCNTs composite has demonstrated excellent fast charging performance with a reversible capacity of 254 mAh/g at 20 A/g. A capacity of 221mAhg−1 after cycling at 10 A/g for 8000 cycles has also been achieved for SIB. As an anode material for PIB, the Bi/MWCNTs composite has delivered excellent rate performances with a reversible capacity of 251 mAh/g at 20 A/g. A specific capacity of 270mAhg−1 after cycling at 1Ag−1 for 5000 cycles has also been achieved for PIB.

Magnetically Grafted Carbon Nanotubes Synthesis and Its Oriented Nanochannels Construction in the Poly(Vinylidene Fluoride) (PVDF) Ultrafiltration Membranes

Carbon nanotubes (CNTs) with hollow nanochannels have attracted much attention in preparing high-performance water treatment membranes. In this paper, the grafting polymer chains, including alkynyl terminated poly(methyl methacrylate) methacrylate (PMMA) single chain and PMMA-b-poly (ethylene glycol) methacrylate [P(PEGMA)] diblock molecular chains, were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. A UV-induced click reaction was used to graft different linear polymers onto the surface of magnetic thiol-functionalized carbon nanotubes (mCNTs-SH). The poly(vinylidene fluoride) (PVDF) composite ultrafiltration membrane within the oriented nanochannels was prepared using phase inversion and magnetic field orientation. TEM and XRD results confirmed that the magnetic carbon nanotubes grafted with a diblock molecular chain had good nano-dispersion and orientation array effects in PVDF composite ultrafiltration membrane. The water contact angle of the array mCNT-g-diblock molecular chain-based composite membrane was 48.5°, significantly enhancing the PEGMA chain segments. The composite membrane with CTNs’ nanochannels attained a higher water flux. As the diblock molecular chain grafted mCNTs oriented in the membrane, the water flux reached 17.6 LMH (five times greater than the pure PVDF membrane), while the molecular weight cut-off (MWCO) for PEG1400 rejection could reach higher than 80%.

Microwave-regulated Bi nanoparticles on carbon nanotube networks as a freestanding electrode for flexible sodium-ion capacitors

High capacity, long cycle life, and fast kinetics are highly desired for alloying anodes in sodium ion capacitors (SICs). However, the huge repeatedly volume changes during the alloying/dealloying process cause electrode pulverization, seriously degrading the capacity and cycling stability. To address this issue, we developed a microwave irradiation technology for the in-situ growth of nano-sized Bi uniformly anchored on the surface of carbon nanotubes (CNTs). The as-synthesized freestanding electrode film effectively retards the pulverization of Bi nanoparticles, enabling fast sodium storage kinetics for high-power performance (278.1 mAh g−1 @ 30 A g−1), as well as high-capacity retention of 94% for over 3,500 cycles. The coin-cell type SICs of a Bi/CNTs anode paired with an activated carbon (AC)/CNTs cathode can deliver a maximum energy density of 128.5 Wh kg−1 and a high power density of 12.3 kW kg−1 with a remaining energy density of 85 Wh kg−1. Additionally, the flexible quasi-solid SICs using a gel electrolyte demonstrated a high volumetric energy density of 21 mWh cm−3 with good cycling stability (90%) for over 1500 cycles. These results show great promise for our developed SICs as the next-generation energy storage to bridge the performance gap between batteries and supercapacitors, as well as for flexible energy storage applications.

Resorc[4]arene Modifiers for Supramolecular Site-Directed Immobilization of Antibodies on Multi-Walled Carbon Nanotubes.

One of the main problems in developing immunosensors featuring carbon nanotubes (CNTs) is immobilizing antibodies (Abs) onto the CNT surface to afford selective binding to target antigens (Ags). In this work, we developed a practical supramolecular Ab conjugation strategy based on resorc[4]arene modifiers. To improve the Ab orientation on the CNTs surface and optimizing the Ab/Ag interaction, we exploited the host-guest approach by synthesizing two newly resorc[4]arene linkers R1 and R2 via well-established procedures. The upper rim was decorated with eight methoxyl groups to promote selective recognition of the fragment crystallizable (Fc ) region of the Ab. Moreover, the lower rim was functionalized with 3-bromopropyloxy or 3-azidopropiloxy substituents to bind the macrocycles on the multi-walled carbon nanotubes (MWCNTs) surface. Accordingly, several chemical modifications of MWCNTs were evaluated. After the morphological and electrochemical characterization of nanomaterials, the resorc[4]arene-modified MWCNTs were deposited onto a glassy carbon electrode surface to evaluate their potential applicability for label-free immunosensor development. The most promising system showed an improved electrode active area (AEL ) of almost 20 % and a site-oriented immobilization of the SARS-CoV-2 spike protein S1 antibody (Ab-SPS1). The developed immunosensor revealed a good sensitivity (23.64 μA mL ng-1 cm-2 ) towards the SPS1 antigen and a limit of detection (LOD) of 1.01 ng mL-1 .