Surface Of Nanotubes Research Articles

(Invited) Sulfur Addition Reaction Onto Carbon Nanotubes

The surface chemistry of carbon nanotubes is of interest for material’s processing and modification of their electronic and optical properties. Here, we present a new sulfur addition reaction to single-wall and multi-wall carbon nanotubes. Depending on the reaction conditions, we find strong evidence of addition reaction, which produces covalent bonding between sulfur atoms and the nanotube surfaces. Raman, TEM, and photoemission results are consistent with the formation of covalent S-C bonds on the sidewalls. DFT calculations also support a formation of sulfur-carbon bonding and predict electronic and vibrational states that are in good agreement with the experimental results. Based on a comparison between theory and experiments, we propose a stable episulfide (GS) grafting, which consists of of a sulfur atom bridging two carbon atoms repeated over the nanotube surface.

(Invited) Correlation Measurements for Carbon Nanotubes with Quantum Defects

Single-photon sources are one of the essential building blocks for the development of photonic quantum technology. In terms of potential practical application, an on-demand electrically driven quantum-light emitter on a chip is notably crucial for integrating photonic integrated circuits. Here, we propose functionalized single-walled carbon nanotube field-effect transistors as a promising solid-state quantum-light source by demonstrating photon antibunching behavior via electrical excitation. The sp3 quantum defects were formed on the surface of (7, 5) carbon nanotubes by 3,5-dichlorophenyl functionalization, and individual carbon nanotubes were wired to graphene electrode pairs. Filtered electroluminescent defect-state emission at 77 K was coupled into a Hanbury Brown and Twiss experiment setup, and single-photon emission was observed by performing second-order correlation function measurements. We discuss the dependence of the intensity correlation measurement on excitation power and emission wavelength highlighting the challenges of performing such measurements while simultaneously analyzing acquired data. Our results indicate a route toward room-temperature electrically-triggered single-photon emission.

GPU-Enabled Exascale Quantum Transport Modeling of Carbon Nanotube Devices

The work will describe our efforts to develop an exascale electrostatic-quantum transport framework, Quantum-eXstatic (https://github.com/AMReX-Microelectronics/eXstatic), currently supporting the modeling of carbon nanotube field-effect transistors (CNTFETs). The framework is capable of modeling realistic three-dimensional structures, efficiently, using CPU/GPU heterogeneous architectures of state-of-the-art supercomputers. It is built on top of the AMReX library, which is a GPU-enabled software library containing functionality for writing particle-mesh applications on structured grids. The Quantum-eXstatic framework comprises three major components: the electrostatic module, the quantum transport module, and the part that self-consistently couples the two modules. The electrostatic module using a finite-volume multigrid solver to compute the electrostatic potential induced by charges on the surface of carbon nanotubes, as well as by source, drain, and gate terminals, which can be modeled using an embedded boundary approach to allow for intricate shapes. The quantum transport module uses the Nonequilibrium Green's Function (NEGF) method to model induced charge. Currently, it supports coherent (ballistic) transport, mode-space approximation for subbands of nanotube, contacts modeled as semi-infinite leads, and Hamiltonian representation using the tight-binding approximation. Special features are being included for accurate modeling of long nanotubes, such as adaptive refinement of integration contours to resolve van Hove singularities in long channels. Particular attention is paid to overlap computations with communication to optimize GPU performance. The self-consistency between the two modules is achieved using Broyden's modified second algorithm, which is parallelized using CPUs and GPUs. Preliminary scaling studies show that the code exhibits ~77% weak-scaling efficiency on 512 NVIDIA A100 GPUs of Perlmutter supercomputer for modeling gate-all-around CNTFETs with a channel length of 13.5 microns at equilibrium conditions. This case involved computations of electrostatic potential in 14.5 billion computational cells and Green’s function computation for a Hamiltonian of size 131,072 x 131,072. For problems of this large size, the code takes about 5 min to reach self-consistency. Figure 1

Construction and Biological Evaluation of Different Nanoshell Thickness Ni@SiO2 Nanotubes as Good Protein Separation Carriers for Bovine Hemoglobin.

Nickel nanomaterials play an important role in biological applications, but they have high toxicity and poor biocompatibility. To overcome these defects, we coated the surface of Ni nanotubes with different thicknesses of SiO2 to reduce cytotoxicity, improve biocompatibility, and broaden their biological application value. This study aimed to construct Ni nanotubes with different thicknesses of SiO2 nanoshells; investigate the effects of silicon layer thickness, incubation time, and cell line category on the cytotoxicity of the as-synthesized materials, and evaluate the biocompatibility of the materials by biological enzymes. The Ni@SiO2-NH2 was selected for use as an adsorbent for the adsorption and purification of histidine-rich proteins, such as Bovine Hemoglobin (BHb). Magnetic Ni nanotubes were prepared by the template-chemical deposition method. A modified version of the Stöber process was used for the SiO2 coating of Ni@SiO2 nanotubes, and adjusted by changing the volume of TEOS for different thicknesses of SiO2 nanoshells. Different cell lines containing tumor cells and normal cells were used in the toxicity experiment, which confirmed the low cytotoxicity and good biocompatibility of Ni@SiO2. To achieve high efficiency of immobilization and purification of histidine- rich proteins, Ni@SiO2-NH2 was obtained by introducing the amino functional group. The Ni@SiO2-NH2 was found to possess lower cytotoxicity and higher adsorption capacity compared to other synthesized materials. Besides, the Ni@SiO2-NH2 also exhibited good selectivity of histidine-rich proteins. This work has not only provided ideas for reducing the cytotoxicity and improving the biocompatibility of biological nanomaterials, but also laid a foundation for subsequent biological applications.

Facile generation of unsaturated-coordinated and atomically-dispersed hafnium active sites for the highly efficient catalytic transfer hydrogenation of levulinic acid

The sluggish kinetic of the hydrogen transfer reaction pose a significant challenge in developing efficient catalytic transfer hydrogenation (CTH) system for upgrading biomass-derived platform molecules. In this contribution, for the first time, hafnium (Hf) species have been found to coordinate with the hydroxyl groups on halloysite nanotubes surface to construct a single-atom Hf catalyst (Hf@HNTs) with unsaturated-coordinated structure at room temperature. Especially, the Hf(1.7)@HNTs delivered an impressive catalytic performance for the CTH of levulinic acid (LvA) to gamma-valerolactone (GVL) with high turn-over frequency (TOF) of 43.1 h−1 at 160 °C, considerably exceeding that of coordination-saturated HfO2 and state-of-art Hf-based catalysts. Experimental and density functional theory (DFT) studies revealed that Hf(1.7)@HNTs possessed unsaturated-coordinated and atomically-dispersed Hf-O Lewis acid-base pairs, which favored the adsorption and activation of LvA. Moreover, DFT calculations explicitly demonstrated that the energy barriers for the hydrogen transfer between the LvA and hydrogen donor were significantly reduced on the Hf(1.7)@HNTs than that of HfO2.

Structure and dynamics of adsorbed water on carbon nanotubes: a molecular dynamics simulation

Water adsorbed on carbon nanotube (CNT) surfaces is known to have unique properties, however, the structure and dynamics of adsorbed water on CNT have been unclarified. We investigated the temperature dependence of the structure and rotational dynamics of adsorbed water on carbon nanotube surfaces using a classical molecular dynamics simulation. At a specific adsorption amount and temperature, a rhombic ice structure and a polygon structure that includes pentamers and hexamers coexist in the adsorbed water. Rotational dynamics analysis indicates that the rhombic ice exhibits solid-like behavior and that the polygon structure exhibits liquid-like behavior. Their coexistence is regarded as a solid–liquid crossover.

Fabrication of water-resistant and abrasion- resistant superhydrophilic coatings

Superhydrophilic coatings show promising applications in the anti-fogging and self-cleaning fields. However, the application of transparent superhydrophilic coatings faces two challenges: abrasion and water immersion leading to loss of superhydrophilicity. Herein, we contribute Halloysite nanotubes (HNTs) to enhancing abrasion resistance by integrating into network-like structures within coatings, and water resistance by adsorbing sodium alkenyl sulfonate (AOS) facilitated by the positive charge within their cavities, respectively. Hydrolyzed tetraethyl orthosilicate (TEOS) as crosslinking agents combines with the abundant hydroxyl groups (Si-OH) on the surface of HNTs nanotubes and glass substrate to form a three-dimensional network structure. The results demonstrate that the designed HNTs tube coatings have strong abrasion and water resistance accompanied by anti-fogging and self-cleaning properties, which can withstand 800 cycles of Taber abrasion under a load of 250 g, and 90 min of immersion in boiling water. Furthermore, the coated surface exhibited negligible contamination after 153 days in an outdoor environment, which indicates a commendable long-term self-cleaning capability. Therefore, the introduction of HNTs nanotubes can provide a useful strategy for the development of superhydrophilic coatings for anti-fogging and self-cleaning with excellent abrasion and water resistance.

Orthogonal Determination of Competing Surfactant Adsorption onto Single-Wall Carbon Nanotubes During Aqueous Two-Polymer Phase Extraction via Fluorescence Spectroscopy and Analytical Ultracentrifugation.

A combination of analytical ultracentrifugation (AUC) and fluorescence spectroscopy are utilized to orthogonally probe compositions of adsorbed surfactant layers on the surface of (7,5) species single-wall carbon nanotubes (SWCNTs) under conditions known to achieve differential partitioning in aqueous two-phase extraction (ATPE) separations. Fluorescence emission intensity and AUC anhydrous particle density measurements independently probe and can discriminate between adsorbed surfactant layers on a (7,5) nanotube comprised of either of two common nanotube dispersants, the anionic surfactants sodium deoxycholate and sodium dodecyl sulfate. Measurements on dispersions containing mixtures of both surfactants indicate near total direct exchange of the dominant surfactant species adsorbed to the carbon nanotube at a critical concentration ratio consistent with the ratio leading to partitioning change in the ATPE separation. By conducting these orthogonal measurements in a complex environment reflective of an ATPE separation, including multiple surfactant and polymer solution components, the results provide direct evidence for the hypothesis that it is the nature of the adsorbed surfactant layer that primarily controls partitioning behavior in selective ATPE separations of SWCNTs.

Novel electrochemiluminescence sensing platform for ultrasensitive detection of malathion residue in tea based on SiO2NSs doped Luminol/AgNPs as a signal amplification strategy

To address the potential hazards of organophosphorus pesticides (OPs) residues in tea, an electrochemiluminescence (ECL) aptasensor based on functionalized nanomaterials was constructed in this work. Firstly, gold nanoparticles (AuNPs) were attached on the surface of multi-walled carbon nanotubes (MWCNTs) by the constant potential electrodeposition to form a compound, and it was utilized to provide excellent immobilization sites for complementary DNA (cDNA). Subsequently, composite nanomaterials were synthesized by a one-pot method with aminated Luminol/silver nanoparticles@silica nanospheres (NH2-Luminol/Ag@SiO2NSs). Finally, NH2-Luminol/Ag@SiO2NSs was combined with a malathion aptamer (Apt) to obtain signal probes (SPs) for the construction of an aptasensor. The aptasensor had a wide linear range (1×10−3-1×103 ng/mL) and a low limit of detection (LOD) (0.3×10−3 ng/mL). It had the virtues of high sensitivity, wonderful stability and excellent specificity, which could be used for the detection of malathion residue in tea. The work provides a proven way for the construction of a rapid and ultrasensitive aptasensor with low-cost.

The benzothiadiazole-based COF/CNT composite as host for efficient Li-S batteries with excellent cycling stability

The cycle stability and dynamic performance of lithium-sulfur (Li-S) batteries have been major challenges, which primarily arise from the dissolution and migration of the soluble reaction intermediates during cycling, as well as the low conductivity of sulfur. In this study, a covalent organic framework containing heteroatoms (B/N/S) is uniformly wrapped on the outer surface of carbon nanotubes to form a nanocomposite (COF@CNT). The composite combines the excellent electrical conductivity of CNTs and the COF material containing evenly distributed heteroatoms that can adsorb and catalyze polysulfides. B atom on COF can be chemically adsorbed by the negatively charged SX2−, S and N atoms can interact with Li+ to reduce the “shuttle effect”. At the same time, the heteroatoms promote the liquid-to-solid phase conversion of the soluble long-chain Li2Sx (4 ≤ x ≤ 8), and the subsequent conversion of solid Li2S2 to Li2S, thereby enhancing the dynamic kinetics. As a cathode material, COF@CNT/S exhibits an initial specific capacity of 1176 mAh/g at 0.2 C, maintaining a capacity of 688 mAh/g after 1000 cycles at 1 C with a Coulombic efficiency of 99.7 %. Notably, a quite low capacity decay rate of 0.029 % per cycle has been achieved, making the COF@CNT/S cathode one of the most stable electrode material for Li-S batteries. This work provides insights into improving cycle performance of Li-S batteries, and also enriches the current study on host materials.

Robust superhydrophobic self-cleaning coating prepared by silane modified multi-walled carbon nanotubes: A combined experimental and molecular dynamics study

As a functional material, superhydrophobic coating has been widely studied in the field of self-cleaning. However, obtaining superhydrophobic coatings with robustness through simple preparation processes remains a challenge. In this paper, a robust superhydrophobic coating is prepared based on multi-walled carbon nanotubes modified by octyltrimethoxysilane, and its performance and hydrophobic mechanism are studied by experiments and molecular dynamics simulation. The superhydrophobic coating is prepared by one-step spraying method. The coating is characterized and analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy, and the properties of the coating are tested by experiments. Molecular dynamics simulation is used in the study to construct a molecular model system, and the molecular modification mechanism and coating wettability are simulated under the COMPASSII force field. The results show that octyltrimethoxysilane successfully modified carbon nanotubes, and the hydroxyl groups at the head of the molecular chain are bound to the surface of the carbon nanotubes in the form of hydrogen bonds, while the tail of the molecular chain is far away from the surface. After modification, the surface of carbon nanotubes changed from hydrophilic to hydrophobic. The prepared superhydrophobic coating not only has excellent self-cleaning properties, but also exhibits corrosion resistance to acid and alkali solutions. The coating still has superhydrophobic when the wear length is in the range of 400 cm. It can be seen that a robust superhydrophobic self-cleaning coating is successfully prepared by a simple one-step spraying method. The modification mechanism and the hydrophobic mechanism of the coating were obtained by the combination of experiment and molecular dynamics simulation, which provided theoretical support for the superhydrophobic of the coating at the micro level.

Interaction of Titanium Atoms with the Surface of Perfect and Defective Carbon Nanotubes

The dispersion of metal atoms over the surface of 1D and 2D carbon systems is the most affordable way to control their properties, which are attractive for many applications in electronics, power engineering, and catalysis. In this work, the features of the interaction of titanium atoms with the surface of carbon nanotubes, caused by various structural defects on these surfaces, were studied by first-principles computer simulation based on the density functional theory. Nanotubes (7, 7) and (11, 0) with similar diameters (≈1 nm) but different types of conductivity, metallic and semiconductor, respectively, were chosen for the study. Three types of defects were studied: a single vacancy, a double vacancy, and a topological defect. Two possible orientations of each type of defect relative to the tube axis were considered. We mainly used the basis of atomic-like orbitals (the SIESTA package) and in some test calculations also the basis of plane waves (the VASP package). Computational experiments have shown that the binding energy of Ti atoms with a defect-free nanotube is always lower than with defective ones, regardless of the used approximation for the exchange-correlation functional (LDA or GGA). The binding energies predicted in the LDA approximation are noticeably higher than in the GGA approximation (up to ~15% for the (7, 7) tube and up to ~50% for the (11, 0) tube). The strongest coupling occurs when the titanium atom is adsorbed on a nanotube with a single vacancy. The resulting configuration can be considered as a defect in the substitution of one carbon by a titanium atom.

Sunlight-mediated removal of endocrine disruptors from wastewater using trimetallic core-shell Ag-TeO2@ZnO nanocomposites

The current work emphasizes the preparation of trimetallic core-shell Ag–TeO2@ZnO nanocomposites (NCs) by thermo-mechanical method for the efficient photocatalytic degradation of 2,4-Dichlorophenol and β-naphthol pollutants. FE-SEM shows that Ag and TeO2 nanoparticles are deposited on the surface of ZnO nanotubes. The band gap of pristine ZnO NPs and 5 wt% Ag–TeO2@ZnO nanocomposites are found to be 3.16 and 2.96 eV, respectively. The calculated specific surface area (SBET) of pristine ZnO NPs and 5 wt% Ag–TeO2@ZnO nanocomposites are 40.47 and 45.66 m2 g−1 respectively, confirming that Ag and TeO2 nanoparticles contribute to increasing in surface area of pure ZnO. The synthesised nanocomposite showed excellent photocatalytic performance for the degradation of β -naphthol (95.6%) in 40 min at the concentration of (0.6 mg ml−1) and 2,4-DCP (99.6%) in 180 min (0.4 mg ml−1) under natural sunlight. Cyclic Voltammetry and Electrochemical Impedance Spectroscopy were carried out to study the electrochemical properties. The determination of reactive oxygen species (ROS) confirmed that the degradation of the pollutants by 5 wt% Ag–TeO2@ZnO NCs was due to the formation of superoxide radicals. Electron paramagnetic resonance revealed the presence of sharp signals in pure ZnO nanoparticles at g ∼1.95 and oxygen vacancy peak at g ∼2.01 in 5 wt% Ag–TeO2@ZnO NCs. To study the mechanism behind the degradation of pollutants, Scavenger test using histidine and ascorbic acid (ROS scavengers) was performed. The synthesised nanocomposites are highly stable and showed enhanced efficiency up to three cycles, confirming their reusability as a photocatalyst.

Lanthanum nanoparticle decorated carbon nanotubes: Facile method of synthesis and studies of their redox stability, cytotoxicity and corrosion inhibition on the magnesium alloy in 3.5 % NaCl environment

Functionalized carbon materials can act as high-temperature coatings and eco-friendly composite materials. We have studied lanthanum-doped carbon nanotube (La-CNT) material redox behavior, cytotoxicity, and corrosion inhibition efficiency. The La-CNT material has been characterized by different techniques to confirm the presence of functional groups. The Fourier transform infrared (FTIR) and Raman studies were performed to investigate the functional groups and carbon defects. Field emission scanning electron microscopy (FESEM) and tunneling electron microscopy (TEM) studies were used to investigate the carbon nanotube microstructure, La nanoparticles were shown to interact with the carbon nanotube surface. X-ray diffraction (XRD) techniques were used to confirm the crystallinity of composite material. Electrochemical methods were used to investigate corrosion inhibition and redox stabilities. After corrosion study on the Mg alloy its microstructure was analyzed to confirm the composite material inhibition efficiency. The composite material showed significant cytotoxicity, and corrosion inhibition efficiency was shown to be 82 % as compared with pristine epoxy-coated Mg alloy.XPS results are suggested that alloy oxide layer formed. The DFT study supported the experimental findings.

Sequence-Dependent Surface Coverage of ssDNA Coatings on Single-Wall Carbon Nanotubes.

A combination of experimental measurements and molecular dynamics (MD) simulations was used to investigate how the surfaces of single-wall carbon nanotubes (SWCNTs) are covered by adsorbed ssDNA oligos with different base compositions and lengths. By analyzing the UV absorption spectra of ssDNA-coated SWCNTs before and after coating displacement by a transparent surfactant, the mass ratios of adsorbed ssDNA to SWCNTs were determined for poly-T, poly-C, GT-containing, and AT-containing ssDNA oligos. Based on the measured mass ratios, it is estimated that an average of 20, 22, 26, or 32 carbon atoms are covered by one adsorbed thymine, cytosine, adenine, or guanine nucleotide, respectively. In addition, the UV spectra revealed electronic interactions of varying strengths between the nucleobase aromatic rings and the nanotube π-systems. Short poly-T DNA oligos show stronger π-π stacking interactions with SWCNT surfaces than do short poly-C DNA oligos, whereas both long poly-C and poly-T DNA oligos show strong interactions. These experiments were complemented by MD computations on simulated systems that were constrained to match the measured ssDNA/SWCNT mass ratios. The surface coverages computed from the MD results varied with oligo composition in a pattern that correlates higher measured yields of nanotube fluorescence with greater surface coverage.

Synergistic effect of carbon nanotube and encapsulated carbon layer enabling high-performance SnS2-based anode for lithium storage

Tin disulfide (SnS2), due to large interlayer spacing and high theoretical capacity, is regarded as a prospective anode material for lithium-ion batteries. Nevertheless, the poor electron conductivity of SnS2 and huge volumetric change during the lithiation/delithiation process lead to a rapid capacity decay of the battery, hindering its commercialization. To address these issues, herein, SnS2 is in-situ grown on the surface of carbon nanotubes (CNT) and then encapsulated with a layer of porous amorphous carbon (CNT/SnS2@C) by simple solvothermal and further carbonization treatment. The synergistic effect of CNT and porous carbon layer not only enhances the electrical conductivity of SnS2 but also limits the huge volumetric change to avoid the pulverization and detachment of SnS2. Density functional theory calculations show that CNT/SnS2@C has high Li+ adsorption and lithium storage capacity achieving high reaction kinetics. Consequently, cells with the CNT/SnS2@C anode exhibit a high lithium storage capacity of 837 mAh/g after 100 cycles at 0.1 A/g and retaining a capacity of 529.8 mAh/g under 1.0 A/g after 1000 cycles. This study provides a fundamental understanding of the electrochemical processes and beneficial guidance to design high-performance SnS2-based anodes for LIBs.

Physical Adsorption of Polyacrylic Acid on Boron Nitride Nanotube Surface and Enhanced Thermal Conductivity of Poly(vinyl alcohol) Composites.

To fully tap into the potential of boron nitride nanotubes (BNNTs), addressing their inherent insolubility was imperative. In this study, a water-soluble polymer, poly(acrylic acid) (PAA), was employed as a surface-active reagent, using an accessible and scalable approach. The physical properties and structure of PAA-BNNT were meticulously confirmed through valuable characterization techniques, encompassing X-ray diffraction, scanning electron microscopy, Fourier-transform infrared, X-ray photoelectron spectroscopy, and thermogravimetric analysis. PAA-BNNT exhibited remarkable dispersion in water and demonstrated compatibility with the poly(vinyl alcohol) (PVA) matrix. When incorporating 30 wt % of PAA-BNNT (about 24.75 wt % net BNNT) into the PVA matrix, the thermal conductivity surged by over 21.7 times compared to pure PVA due to the uniform dispersion of high-concentration PAA-BNNT in the polymer matrix.

Understanding adsorption ability of CNT (6, 6-6) and BNNT (6, 6-7) nanotubes for a novel hybrid pyrazole-indole drug, InPy-7a

The quest for enhanced drug delivery efficacy across diverse physiological conditions has spurred the exploration of various nanomaterials, including carbon-based materials like carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs). These materials offer high surface areas conducive to increased drug loading, with considerations such as surface charge, size, shape, and biocompatibility being paramount. The hybrid drug, synthesized by combining indole derivatives with a pyrazole moiety, has shown promising cytotoxicity against various cancer cell lines. In this context, we have explored the adsorption ability of CNT (6, 6-6) and BNNT (6, 6-7) nanotubes for a novel hybrid drug, InPy-7a, using density functional theory (DFT) calculations. Our study has aimed to elucidate the adsorption mechanisms and electronic properties of InPy-7a on the surfaces of CNT (6, 6-6) and BNNT (6, 6-7). Through computational tools, we have analyzed the geometry optimization of InPy-7a onto the nanotube surfaces, evaluating molecular interactions, quantum descriptors, frontier molecular orbitals (FMO), natural bond orbitals (NBO), nuclear magnetic resonance (NMR), and molecular electrostatic potential (MEP). Our results have illuminated the underlying mechanisms by revealing unique interactions and electronic changes during complexation. Based on predicted electronic aspects and molecular interactions, the CNT@InPy-7a-S5 complex system showed greater chemical reactivity, adsorption, and stability than BNNT@InPy-7a-S6. These findings open up opportunities for additional experimental validations and offer insightful information about the possible uses of drug delivery systems based on nanotubes.

The Effect of Silanized Halloysite Nanotubes on the Structure of Polyethylene-Based Composite.

Chemical modification of the surface of halloysite nanotubes (HNT) by alkalization (with sodium hydroxide (NaOH)) and grafting with silanes (bis(trimethylsilyl)amine (HMDS)) was carried out. The efficiency of the alkalization and grafting process was evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and the nitrogen adsorption method were used. XRD and FTIR analysis confirmed the formation of bonds of trimethylsilyl groups to the HNT surface which changed the nature of the surface from hydrophilic to hydrophobic. In addition, it was noted that grafting with silanes decreases by 7.2% the specific surface area of the halloysite compared to the alkalized material. High-density polyethylene (HDPE) composites with halloysite (HNT), alkalized halloysite (alk-HNT), and HMDS-modified halloysite (m-HNT) were processed in the molten state in a Brabender mixer chamber. On SEM/EDS micrographs of HDPE composites with silanized HNT, a change in surface characteristics from smooth to ductile was observed. Higher melting point values based on differential scanning calorimetry (DSC) analysis of HDPE composites with 5%wt silanized halloysite in comparison with HNT and alk-HNT of, respectively, 2.2% and 1.4% were found, which indicates a slight beneficial influence of the filler on the quality of ordering of the crystalline phase of the matrix.

Preparation and photocatalytic performance of BiOCl nanosheet–TiO2 nanotube array composites

Combining BiOCl with TiO2 nanomaterials is beneficial to enhance the photocatalytic activity and optoelectronic activity. In this paper, BiOCl nanosheet–TiO2 nanotube array composites were synthesized to enhance the photocatalytic degradation performance for methyl orange (MO) of TiO2 under ultraviolet light irradiation. BiOCl nanosheets were deposited on TiO2 nanotube arrays by the straightforward impregnation method. X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and photocurrent (i–t) were used to evaluate the composites of BiOCl nanosheets–TiO2 nanotube arrays. The results showed that the tetragonal BiOCl nanosheets clustered together on the surface of the TiO2 nanotubes and grew along the (110) crystal plane. The composites outperformed pure TiO2 regarding outstanding structure and overall photocatalytic performance, and the MO photocatalytic degradation rate was 98.5%. For the 30-BiOCl–TiO2, its photocurrent intensity (58 µA) was 4.5 higher than TiO2 (13 µA). The degradation rate of 87% can still be reached after three cycles.