Surface Of Nanotubes Research Articles

Surface defect and carbonyl engineering of CNTs via oxygen-plasma etching: Oriented production of singlet oxygen from peroxymonosulfate activation

A facile oxygen-plasma strategy was used to engineer carbon nanotubes (CNTs) surface with defects and carbonyl groups for organic water decontamination. The plasma-treated CNTs (E-CNTs) displayed a remarkable efficacy to catalyze peroxymonosulfate (PMS) activation for degrading electron-rich pollutants across a broad range of pH levels and under natural water conditions. Moreover, the kinetic constant for E-CNTs was found to be 4.1 times that of raw CNTs, attaining 97 % 2,4-DCP degradation in 20 min. The in situ capturing by electron paramagnetic resonance, chemical probing, and selectively scavenging tests collectively reveal that singlet oxygen (1O2) was the dominant reactive species with 54.9 % contribution to 2,4-DCP removal. The structure–activity relationship analysis and density functional theory (DFT) revealed that defects and carbonyl groups were the intrinsic catalytic sites for PMS activation. A comprehensive degradation pathway was proposed based on the properties of pollutant and degradation products from HPLC-MS and DFT calculations. Based on the ECOSAR analyses, the toxicity of the treated water (degradation intermediates) dramatically declined except for a polymerized bipolymer TP6 (m/z = 266.9). This article provides a novel method to create PMS-oriented active sites on carbon materials for selective singlet oxygen production and water purification.

Infrared Light-Emitting Diodes Based on Chirality-Sorted Carbon Nanotube Films.

An important goal in carbon nanotube optoelectronics is to achieve a high-performance near-infrared light source. But there are still many challenges such as the purity of single-walled carbon nanotube (SWCNT) chirality, nonradiative defects, thin-film quality, and device structure design. Here, we realize infrared light-emitting diodes (LEDs) based on chirality-sorted (10, 5) SWCNT network films, which operate at a low bias voltage and emit at a telecom O band of 1290 nm. Asymmetric palladium (Pd) and hafnium (Hf) contacts are used as electrodes for hole and electron injection, respectively. However, the large Schottky barrier at the interface of the SWCNTs and the Hf electrode, primarily resulting from the polymer wrapped on the nanotube surface during the sorting process, leads to inefficient electron injection and thus a low electroluminescence efficiency. We find that the efficiency of electron injection can be improved by the local doping of the nanotubes with dielectric layers of YOX-HfO2, which reduces the Schottky barrier at the SWCNT/Hf interface. Accordingly, the (10, 5) SWCNT film-based LED achieves an external quantum efficiency of larger than 0.05% without any optical coupling structure. With further improvement, we expect that such an infrared light source will have great application potential in the carbon nanotube monolithic optoelectronic integrated system and on-chip optical interconnection, especially in the field of short-distance optical fiber communications and data center.

Ionic Strength-Mediated "DNA Corona Defects" for Efficient Arrangement of Single-Walled Carbon Nanotubes.

Single-stranded DNA oligonucleotides wrapping on the surface of single-walled carbon nanotubes (SWCNTs), described as DNA corona, are often used as a dispersing agent for SWCNTs. The uneven distribution of DNA corona along SWCNTs is related to the photoelectric properties and the surface activity of SWCNTs. An ionic strength-mediated "DNA corona defects" (DCDs) strategy is proposed to acquire an exposed surface of SWCNTs (accessible surface) as large as possible while maintaining good dispersibility via modulating the conformation of DNA corona. By adjusting the solution ionic strength, the DNA corona phase transitioned from an even-distributed and loose conformation to a locally compact conformation. The resulting enlarged exposed surface of SWCNTs is called DCDs, which provide active sites for molecular adsorption. This strategy is applied for the arrangement of SWCNTs on DNA origami. SWCNTs with ≈11nm DCD, providing enough space for the adsorption of "capture ssDNA" (≈7nm width required for 24-nt) extended from DNA origami structures are fabricated. The DCD strategy has potential applications in SWCNT-based optoelectronic devices.

Natural halloysite nanotubes decorated with organophosphorous for highly flame‐resistant epoxy composites

AbstractHighly flame‐resistant epoxy composites have important application value in many industrial fields. Unfortunately, epoxy resins (EPs) are inherently flammable materials and exhibit great fire hazard. In this study, the commercially available 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was chemically immobilized on the surface of natural halloysite nanotubes (HNTs) via the linkage of vinyltrimethoxysilane to obtain a novel flame‐retardant VD@HNTs containing P/Si/Al elements. It was found that the flame‐retardant VD@HNTs can effectively improve the thermal stability and flame resistance of epoxy composites. Typically, when 10% of VD@HNTs is added in EP, the limiting oxygen index of as‐prepared VD@HNTs/EP composites reaches 30.3%, and it also successfully reaches V‐0 classification in the UL‐94 test. Besides, the ignition time of VD@HNTs/EP composites was enhanced from 42 s for pure EP to 60 s, and the maximum heat release rate was reduced from 1221 to 758 kW∙m−2. These great findings promise an innovative and efficient strategy for improving the fire safety of EP products and may also offer valuable insight toward fabricating various novel organic–inorganic flame retardants as well as highly flame‐resistant polymer composites.Highlights A novel flame‐retardant VD@HNTs containing P/Si/Al elements was prepared by the chemical decoration of HNTs with organophosphorous. The VD@HNT can effectively improve the thermal stability and flame resistance of epoxy composites. Synergistic flame‐retardant mechanism of phosphorus‐based flame retardants and natural HNTs was classified.

Quantitative XPS analysis of amine-terminated dendritic functionalized halloysite nanotubes decorated on PAN nanofibrous membrane and adsorption/filtration of Cr(VI)

Quantitative XPS analysis of the active functional groups on the surface of nanofiber membranes is an important issue for evaluating the potential efficiency of the membranes in removing heavy metals from aqueous solutions. This research is developing a novel composite nanofiber for accessibility adsorption groups on the surface of the electrospun membrane for effective removal of Cr(VI). For this purpose, three generations (G1, G2, and G3) of poly(amidoamine) dendrimers (PAMAM) were grafted onto the surface of halloysite nanotubes (HNTs). Functionalized HNTs (F-HNTs) were decorated on the surface of polyacrylonitrile (PAN) nanofiber layers in different ratios by simultaneous electrospinning and electrospraying techniques. The results showed that the decoration with F-HNTs made the surface of the membranes superhydrophilic. The removal efficiency of the optimal sample with 10 % third-generation F-HNTs (PAN/HNTs-G3-10 %) reached 96 % within 5 min. The mechanism for the removal of Cr(VI) ions in the PAN/HNTs-G3-10 % membrane was electrostatic interaction, chelation, and reduction. X-ray photoelectron spectrometer (XPS) analysis was used to characterize the quantitative and qualitative correlation dependencies between the removal of Cr(VI) and the amine functional groups of different generations decorated onto the electrospun layer. Quantitative analysis of the amine-terminated dendritic groups has revealed that the percentage of Cr(VI) removal is proportional to the number of terminal amine groups. Furthermore, PAN/HNTs-G2 and PAN/HNTs-G3 composite nanofiber membranes showed significantly lower leachability of nanoparticles and higher mechanical strength compared to other membranes due to the formation of ionic bonds between the amine-terminated dendritic of HNTs-G2 and HNTs-G3 and the cyanide groups of PAN. Effects of competing heavy metal ions on Cr(VI) adsorption follow the order of Zn(II) > Cu(II) > Ni(II).

CuNi2O4/MWCNTs nanocatalyst for methanol and ethanol electro-oxidation

The widespread use of cheap and efficient catalysts in energy storage and production in electrochemical processes led our research team to the synthesis and evaluation of CuNi2O4/MWCNTs nanocatalyst for alcohol oxidation. Nanocatalyst was characterized in terms of structure and morphology by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDAX). The ability of CuNi2O4/MWCNTs was evaluated with cyclic voltammetry (CV) and linear sweep voltammetry (LSV) analyses in the oxidation process of methanol and ethanol alcohols in alkaline media. The optimal concentration of methanol and ethanol for CuNi2O4/MWCNTs and CuNi2O4 was obtained to investigate the methanol oxidation reaction and ethanol oxidation reaction processes. The mechanism of these processes was also evaluated in detail. The stability of both nanocatalysts was investigated by performing several consecutive CVs and in 3600 s by chronoamperometric analysis. The results showed the good stability of this catalyst. The synergistic effect of placing CuNi2O4 on the surface of carbon nanotubes improved the oxidation process of methanol and ethanol. In general, the proposed catalyst can be an efficient, stable, and cheap option and at the same time very stable for use in alcohol fuel cells.

Towards promoting wound healing: A near-infrared light-triggered persistently antibacterial, synergistically hemostatic nanoarchitecture-integrated chitosan hydrogel

The skin, the primary barrier of the body, is inevitably broken. However, the development of materials that facilitate wound healing with sustained antimicrobial, hemostatic, and biocompatible properties remains a formidable challenge. In this article, we prepared a photopolymerizable composite hydrogel consisting of a hydrogel matrix, a hemostatic/antibacterial agent, and a photothermal therapy agent. The photopolymerizable hydrogel matrix was prepared by grafting the photoinitiator and polymerizable active monomer onto the chitosan chain segment, which exhibits excellent biocompatibility. Furthermore, linalool is adsorbed on the surface of halloysite nanotubes (HNTs) to form a hemostatic and antibacterial. Meanwhile, dopamine is employed as a coating material for hollow glass microsphere (HGM), which enables them to function as photothermal therapy agents. Upon exposure to near-infrared radiation, the PHA hydrogel releases linalool molecules from the surface of the HNTs, which diffuse into the hydrogel matrix, resulting in a sustained antimicrobial effect. At the same time, rapid curing of the photopolymerizable hydrogel under UV light forms a physical barrier that synergistically enhances the hemostatic properties of the HNTs. From the above, the results pave the way to develop a potential hemostatic antimicrobial dressing for clinical use in wound healing.

Use quantum mechanical computational methods to investigate interactions between imidacloprid and boron nitride nanotubes

The study investigates the interaction between a boron nitride nanotube (BNNT) and an imidacloprid (IM) molecule. The structure of the BNNT is detailed, measuring 9.964 Å in diameter and 18.186 Å in length. Six interaction geometries (BNNT_IM_1 to BNNT_IM_6) between BNNT and IM are investigated, with BNNT_IM_6 showing the most thermodynamically stable interaction. The electronic interaction energies are calculated, and BNNT_IM_6 presents the lowest value (−1.89 eV), indicating a favorable interaction. Quantum theory of atoms in molecules (QTAIM) and analysis of noncovalent interactions (NCI) support the findings. BNNT_IM_6, with IM inside the nanotube, shows the highest electron sharing, explaining its superior stability. The chlorine-BNNT interaction was revealed to be a determining attractive component. The attraction/repulsion indices highlight BNNT_IM_1 as having the most attractive interaction, driven mainly by oxygen-BNNT and chlorine-BNNT interactions. The investigation emphasizes the importance of considering multiple factors, including electron density and interaction volume, in evaluating the strength of BNNT-IM interactions. This study model opens a proposal to assess the impact of functional groups, from a physicochemical perspective, of a molecule interacting with a nanotube surface.

Surface characterization and antibacterial efficiency of well-ordered TiO2 nanotube surfaces fabricated on titanium foams

Titanium (Ti)-based implants are not compatible enough due to their bio-inert character, insufficient antibacterial capabilities and stress-shielding problem for dental and orthopaedic implant applications. Thus, this work focused to fabricate, analyze and improve antibacterial properties titanium dioxide (TiO2) nanotube array surfaces on Ti foam by anodic oxidation (AO) process. The well-ordered nanotube arrays with approximately 75 nm were successfully fabricated at 40 V for 1 h on Ti foams. Ti and O were observed as major elements on AO-coated Ti foam surfaces. In addition, the existence of TiO2 structure was proved on AO-coated foam Ti surfaces. For potential dental and orthopedic implant application, in vitro antibacterial properties were investigated versus Staphylococcus aureus and Escherichia coli. For both bacteria, antibacterial properties of TiO2 nanotube surface were greater than bare Ti foam. The bacterial inhibition versus Staphylococcus aureus and Escherichia coli of TiO2 nanotube surfaces are improved as 53.3% and 69.4% compared to bare Ti foam.

Enhanced electrocatalytic performance of PtNi bimetallic alloys on carbon nanotube for ethanol oxidation reaction

In this paper, Ni-Pt bimetallic alloy nanoparticles were loaded on carbon nanotubes to prepare Ni-Pt nanoparticles/carbon nanotubes composites (Ni-Pt NPs/CNTs) as excellent catalytic materials for ethanol electro-oxidation reaction (EOR). X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and special aberration corrected transmission electron microscope (STEM) were used to characterize its morphology and structure. The activity and stability of the composite were measured by cyclic voltammetry (CV) and chronoamperometry (CA). The catalytic performance was explored by adjusting the ratio of Ni to Pt. Performance test results showed that the Ni-Pt alloy formed 10–15 nm spherical particles and dispersed uniformly on the surface of carbon nanotubes. The Ni1Pt1 NPs/CNTs composite showed excellent performance for EOR. Its mass activity of ethanol electro-oxidation was 620 mA·mg−1Pt, which was 5.08, 18.2 times higher than that of commercial Pt/C and Pt black catalyst, respectively.

MoS2 thin film decorated TiO2 nanotube arrays on flexible Ti foil for solar water splitting application

MoS2/TiO2 nanostructure provides a lot of advantages in photoelectrochemical (PEC) applications due to the absorption of the wide spectrum solar radiation, more catalytically active sites, proper band alignment, and better separation of photogenerated charge carriers. Here we report PEC water splitting studies of MoS2 thin film grown by chemical vapor deposition on TiO2 nanotubes fabricated on flexible thin Ti foil. Raman and x-ray diffraction analysis confirmed the polycrystalline growth of a few layers MoS2 on TiO2/Ti through their characteristic peaks. Field emission scanning electron microscopy revealed the nanotube surface morphology of TiO2 having a diameter in the range of 200–300 nm. The chemical and electronic composition of MoS2 and TiO2 were investigated by x-ray photoelectron spectroscopy. PEC measurements performed in 0.5 M Na2SO4 aqueous electrolyte solution under 100 mW cm−2 (AM 1.5G) simulated sunlight revealed 2-fold improved photocurrent density for MoS2/TiO2 heterostructure (∼135.7 μA cm−2) compared to that of bare TiO2 (∼70 μA cm−2). This is attributed to extended light absorption and more catalytically active surface area resulting from MoS2 functionalization of the TiO2 nanotubes, which results in better PEC activity. This study provides a new insight to explore the performance of thin metal foil-based photoelectrode in PEC applications that can be beneficial to develop roll-to-roll device fabrication to advance futuristic flexible electronics.

Possible formation of H2 hydrates in different nanotubes and surfaces using molecular dynamics simulation.

In this work, we simulated water molecules confined in carbon, boron nitride (BN), and silicon carbide (SiC) nanotubes with similar sizes. We also simulated water molecules confined between parallel graphene, BN, and SiC surfaces in two cases: (a) a similar geometric surface density of water of 0.177/Å2, in which the number of gas molecules was 18% of the total water molecules, and (b) a similar density profile of water of 0.04-0.05 dalton per Å3. To examine H2 hydrate formation, we added guest H2 molecules to the confined water molecules in the nanotube and surface systems. We analyzed the formed shapes, adsorption energies, radial distribution functions (RDFs), and self-diffusion coefficients of the confined molecules in gas hydrate formation. Our results showed that a more ordered heptagonal ice nanotube was formed in the BN nanotube than that in the other systems. After the addition of H2 molecules in the different nanotubes, some of the H2 molecules occupied the wall of the ice nanotube and some of them positioned in the hollow space. Although gas hydrates were created in all surface systems, ordered gas hydrate shapes were formed only in the graphene system. The adsorption energy for guest H2 molecules between the different surfaces was negative, which means that the formation of H2 hydrates between these surfaces is a spontaneous process (unlike that in the nanotube systems). According to RDF results, the BN nanotube and graphene surfaces are proper systems to form more ordered H2 hydrate structures. The confined water molecules have much higher diffusion coefficients in the BN nanotube and graphene surfaces than in the other systems. The F 4 parameter also substantiated hydrate formation in the different nanostructures. In a new configuration of BN and SiC systems with density profiles similar to that of the graphene system, the H2 hydrate was not formed completely as in the case of the graphene system. H2 hydrates formed in the new BN and SiC surfaces were less than those formed in the primary structures (with a geometrical density similar to that of the graphene system) and the graphene system.

Radial nanotubes for nanoelectronics elements: structure and diffraction

Formulation of the problem. Nanotubes are promising objects for the development of nanoelectronic elements. The range of electronic properties of nanotubes can be significantly expanded by synthesizing structures on their surface. Such structures have a radial cylindrical lattice; a number of nanowires have a similar lattice. Radial crystals are a new group of cylindrical structures, the study of which is at an early stage. Therefore, it is necessary to develop both ideas about the structure of radial crystals and a method for their structural analysis. The aim. Consider the simplest radial structures and the features of diffraction by them. Results. A description of the close-packed structure of nanowires and atomic layers with bcc, fcc, and hcp radial lattices sorbed on the nanotube surfaces is proposed, taking into account the effect of radial relaxation. A linear approximation is proposed that makes it possible to quantitatively describe radial relaxation at the initial stage of block growth. The quantitative kinematic theory of Fraunhofer diffraction on achiral radial structures is considered as the basis for their structural analysis, and formulas relating the parameters of the direct and reciprocal lattices are obtained. The results of model calculations of scattering intensity distributions by layer planes of the reciprocal lattice of radial crystals and along the layer lines of their diffraction patterns are presented. Schemes of diffraction patterns of radial crystals with bcc, fcc, and hcp radial lattices are presented. The applicability of traditional selection rules and the significant dependence of the positions of pseudo-orthogonal reflections on the crystal size are shown. Practical significance. The proposed description of radial structures with bcc, fcc, and hcp radial lattices and the diffraction method of structural analysis of their achiral varieties will provide structural control of the products of their synthesis, which is necessary when carrying out a wide range of studies both at the stage of development work on the synthesis of nanoelectronic elements, and for technological control during their industrial production.

Titania (TiO2) nanotube surfaces doped with zinc and strontium for improved cell compatibility.

Titanium-based orthopedic implants are gaining popularity in recent years due to their excellent biocompatibility, superior corrosion resistance and lightweight properties. However, these implants often fail to perform effectively due to poor osseointegration. Nanosurface modification approaches may help to resolve this problem. In this work, TiO2 nanotube (NT) arrays were fabricated on commercially available pure titanium (Ti) surfaces by anodization and annealing. Then, zinc (Zn) and strontium (Sr), important for cell signaling, were doped on the NT surface by hydrothermal treatment. This very simple method of Zn and Sr doping takes less time and energy compared to other complicated techniques. Different surface characterization tools such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), static water contact angle, X-ray diffraction (XRD) and nanoindentation techniques were used to evaluate the modified surfaces. Then, adipose derived stem cells (ADSCs) were cultured with the surfaces to evaluate cell adhesion, proliferation, and growth on the surfaces. After that, the cells were differentiated towards osteogenic lineage to evaluate alkaline phosphatase (ALP) activity, osteocalcin expression, and calcium phosphate mineralization. Results indicate that NT surfaces doped with Zn and Sr had significantly enhanced ADSC adhesion, proliferation, growth, and osteogenic differentiation compared to an unmodified surface, thus confirming the enhanced performance of these surfaces.

Local hydroxide ion enrichment at the inner surface of lacunaris perovskite nanotubes facilitates the oxygen evolution reaction.

Numerous strategies have been devised to optimize the intrinsic activity of perovskite oxides for the oxygen evolution reaction (OER). However, conventional synthetic routes typically yield limited numbers of active sites and low mass activities. More critically, the sluggish mass transfer poses a huge challenge, particularly under high polarization conditions, which impedes the overall reaction kinetics. Herein, lacunaris La0.5Pr0.25Ba0.25Co0.8Ni0.2O3-δ nanotubes (LPBCN-NTs) were prepared via electrospinning and post-annealing, which exhibited a small overpotential of 358.8 mV at 10 mA cm-2 and a lower Tafel slope of 71.46 mV dec-1, superior to the values for the same stoichiometric LPBCN nanoparticles and solid nanofibers, state-of-the-art counterparts and commercial IrO2. Density functional theory calculations revealed that the surface oxygen vacancies in LPBCN-NTs significantly lowered the OH- adsorption energy, while finite element analysis indicated that the precisely constructed lacunaris NT structure enriched the OH- concentration at its inner surface by an order of magnitude, both of which collectively resulted in accelerated OER kinetics. This study clarifies the underlying mechanism of how the lacunaris nanotubular architecture and the surface oxygen vacancies of perovskite oxides affect heterocatalysis, which undoubtedly paves the way to handling the long-standing issues of sluggish mass transfer rates and poor intrinsic catalytic activity.

Heterointerface and crystallinity engineering of Ru/RuS2 dual co-catalysts for enhanced photocatalytic hydrogen evolution

In this paper, the Ru/RuS2 nanoparticles as dual co-catalysts were self-assembled on the surface of g-C3N4 nanotubes (Ru/RuS2/g-C3N4 NTs) for photocatalytic H2 production. The Ru/RuS2/g-C3N4 NTs showed greatly enhanced photocatalytic H2 production activity (1409 μmol·g−1·h−1), 1.16 times of RuS2/g-C3N4 NTs (1212 μmol·h−1·g−1), 10.51 times of Ru/g-C3N4 NTs (134 μmol·g−1·h−1), and 82.88 times of the pure g-C3N4 NTs (17 μmol·g−1·h−1). Besides, the apparent quantum yield value (AQE) of Ru/RuS2/g-C3N4 NTs is 3.92% at 370 nm. Ru/RuS2 as dual co-catalysts are self-assembled on the surface of g-C3N4 NTs and show strong electronic synergistic interaction between the interfaces, reduce ΔGH* of RuS2 and desorption energy of Ru, and promote the selectivity and activity of HER kinetically and thermodynamically respectively, which exhibits higher photogenerated carrier concentration and lower charge migration resistance than RuS2 and Ru, showing the synergistic effect to facilitate the generation and migration of carriers and provides active sites for photocatalysis.

Hydrothermal synthesis of eco-friendly ZnO/CNT nanocomposite and efficient removal of Brilliant Green cationic dye

In this study, seeking to get a more efficient adsorbent, comparable to the commercially available adsorbent, is attracting significant interest as a good adsorbent for wastewater treatment. An approach according to the use of ZnO NPs loaded on the surface of carbon nanotube (ZnO/CNT) nanocomposite to adsorb Brilliant green (BG) dye. ZnO/CNT nanocomposite was chemically synthesized by hydrothermal method and the physicochemical properties were analyzed extensively by using several techniques such as as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy, (EDX), Transmission electron microscopy (TEM), and Thermogravimetric analysis TGA. The effect of different parameters on adsorption processes such as equilibrium time, pH of solution, adsorbent dosage as well as initial concentration of dye has been examined. Results show contact time was (2.00 h), based on the outputs, high capacity of adsorption even at higher initial concentration of dye. With regard to the kinetic analysis, a pseudo second order kinetic model could successfully describe the process of adsorption (R2 0.9910). Then, we used Langmuir, Freundlich isotherm models to obtain the best fit, indicating the role of a multilayer formation for adsorption of BG on the ZnO/CNT nanocomposite from an aqueous solution. Also, the best multilayer adsorption capacity of BG reached to 94.29 mg g−1. The change in free energy of Gibbs (ΔG), entropy (ΔS), and enthalpy (ΔH) were calculated from experimental adsorption results. The obtained negative value of (ΔG) and positive value of (ΔH) show spontaneous nature and endothermic nature of the adsorption process. The regenerated adsorbents in the acidic media (pH 4.0) and basic media (pH10.0) for their performance to removal of BG. The best regenerating has been distilled water. Therefore, it suggests that (ZnO/CNT nanocomposite) is an effective adsorbent and friendly environmentally and inexpensive substance for effective elimination of the dye from wastewater effluent.

Dried hybrid imogolite nanotubes as solids with a changeable surface area: an insight into textural properties based on the correlation between nitrogen gas adsorption, immersion calorimetry into water, and small angle X-ray scattering.

Powdered samples of three imogolite materials with an inner surface covered with Si-CH3 groups (hybrid IMO-CH3) were prepared by ambient drying at 323 K, freeze drying, and spray drying. Reliable estimates of the intra-tube (SA), inter-tube (SB), and inter-bundle (SC) specific surface areas of these samples were inferred from a model-guided correlation between the results of measurements by small angle X-ray scattering (SAXS), nitrogen gas adsorption, and immersion calorimetry into water. Since the SAXS studies indicated no significant deformations of IMO-CH3 nanotubes upon drying, further studies by gaseous N2 adsorption at 77 K indicated the intra-tube and inter-bundle specific surface areas as being only accessible to this adsorbate. The outer curved surfaces of IMO nanotubes, including the inter-tube surface areas, were evaluated based on the calorimetric measurements of the enthalpy of immersion into water, using the enthalpy of immersion per unit surface area for a modelled curved surface of gibbsite as the conversion factor. Given the uncertainty in the determination of surface areas, the IMO-CH3 samples were found to possess the limiting values of specific surface areas ranging between 1150 and 1480 m2 g-1. In contrast to the two other materials, ambient-dried IMO-CH3 was characterized by the highest value of SC parameter due to the much smaller bundles formed by the constituent imogolite nanotubes. The accessibility of these surface areas, together with the hydrophobic and hydrophilic surface domains, was demonstrated to depend on the nature of the surrounding medium and the size of the adsorbing species.

Green synthesis of copper(II) oxide nanoparticles covered on multiwalled carbon nanotubes modified screen-printed electrode as rapid electrochemical sensing platform for detection of doxepin

In the current research, a modified screen-printed electrode has been made by depositing a copper(II) oxide nanoparticle upon the surface of multiwalled carbon nanotubes (CuO/MWCNTs). Through the use of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and mapping, the characterization of the CuO/MWCNTs modifier was examined. The XRD analysis confirms the in-situ formation of copper(II) oxide nanoparticles with MWCNT. FESEM studies reveal the simultaneous existence of nanoparticles and nanotubes in the prepared nanocomposite material. This kind of morphological orientation has significantly improved the nanocomposite’s catalytic properties. Moreover, EDS analysis and elemental mapping depicts that the presence of nanocomposite containing the elements of Cu, O, and C mentioned. Examining the modified electrode's electrochemical activity revealed good stability and conductivity under a diffusion-controlled procedure, making it an ideal working electrode. Additionally, the doxepin oxidation process at the modified electrode’s surface, an antidepressant medicine, has been examined. The modified electrode had a high doxepin sensitivity at an applied voltage of 780 mV. With a detection limit of 0.17 nM (signal/noise = 3), linear range was also obtained over a wide concentration range of 0.001 µM to 400.0 µM (R2 = 0.9998). What's more, the modified electrode is very resistant to ion poisoning and efficiently prevents interference from the oxidation of typicalinterfering species. Moreover, the CuO/MWCNTs electrode has been utilized to measure the doxepin concentration in actual samples. Aside from having an improved electrocatalytic capability, the modified electrode also has a low working potential and good stability, as well as high sensitivity.

Dependence of reinforcement degree on specific surface on carbon nanotubes (nanofibers) for polymer nanocomposites

It has been shown that the well-known parameter, namely, real specific surface of nanofiller (its aggregates) can be used for description of both surface and structure of carbon nanotubes (nanofibers) in polymer nanocomposites. The relationship between radius of nanofiller annular formations, fractal dimension of surface and specific surface was obtained. In its turn, the reinforcement degree of considered nanocomposites is defined by specific surface of nanofiller only at its fixed content, which is function of size of annular formations for this type of nanofiller. It has been shown that the greatest reinforcing effect can be given carbon nanotubes (nanofibers) having large diameter and radius of their annular formations.