AbstractCyanobiphenyl homologues are important liquid crystals to use in some applications since they exhibit intrinsic properties in a certain temperature interval including room temperature. Recently, generating composites with polymers and liquid crystals by electrospinning has drawn great interest. Here, cyanobiphenyl homologues of chain carbon numbers 5–8 and polyacrylonitrile were spun using single-needle electrospinning for the first time. Morphological, optical, aligning, and thermal properties of spun fibers investigated. The thinnest and thickest fibers were obtained in fibers involving cyanobiphenyl of chain carbon number 5 and 6, respectively considering the scanning electron microscopy images. Also, it was proved that all the cyanobiphenyl members were self-aligned throughout the fibers as a core using polarized optical microscopy. The existence of the cyanobiphenyl homologues in the structure of the fibers was presented by infrared spectroscopy results. In addition, the mass variation depending on temperature and calorimetric measurements were studied. Phase transition temperatures of the bulk cyanobiphenyls and the fibers were compared. The results showed that cyanobiphenyl homologues of chain carbon numbers 5–8 and polyacrylonitrile were able to be spun successfully and the fibers had the potential to be used in applications because the physical properties of the fibers were attractive.

AbstractIn the current contribution, copper-manganese bimetallic oxide nanoparticles attached to carbon nanotube surfaces have been created utilizing a straightforward method rather than complicated machinery. The employed sources of Cu and Mn were copper sulfate and potassium permanganate, which were combined with modified carbon nanotubes and thermally treated at 250, 350, and 450 °C, respectively. As the annealing temperature rises from 250 to 450 °C, the copper-manganese bimetallic oxide nanoparticles adhered to the surface of the carbon nanotubes gradually grow in size from 9 to 45 nm. XRD and FTIR methods were used to study structural characteristics. The existence of copper-manganese bimetallic oxide phases was established based on the results. The peak height and sharpness of the XRD data were also improved by increasing the annealing temperature, reflecting an improvement in the crystallinity. A broadband dielectric spectroscopy (BDS) was used to show how the applied frequency affected the dielectric characteristics.

AbstractMetal binders’ cobalt plays a significant role in the sintering process of polycrystalline diamond compact (PDC), which not only can reduce synthesis temperature and pressure but increase impact ductility of PDC. However, the abundant metal binder cobalt leads to thermal degradation of the PDC and destroys its mechanical properties in oil and gas drilling at elevated temperatures. We removed cobalt by using a solution mixed H2O2 with H2SO4, diluting it by cold water in the process. Since removed cobalt produced holes leading to structural damage, the holes on the surface of the PDC were then filled with suitable HFCVD parameters, and the results were analysed using characterization methods including SEM, EDS, and XRD. With an acid concentration of 10%, the amount of the metal cobalt in the PDC is minimal and depth of cobalt removal up to 70 μm, and this method of removing cobalt increases efficiency and reduces the use of acid, making it eco-friendly. The diamond holes are efficiently filled by the HFCVD technique, resulting in a reduction in surface porosity from 6.701% to 1.756% and a pore filling rate of up to 81.63%, as well as a flatter and denser surface compared to the pre-processed substrate.

AbstractThe present study aims to develop a simple, non-toxic, and environmentally friendly reduced graphene oxide-silver (rGO-Ag) nanohybrid synthesis method by employing three monosaccharides which are ribose, fructose, and galactose, as the reducing agents. This study also investigated the formation and crystalline structures of the rGO-Ag formed. The resultant nanohybrids were characterised via ultraviolet-visible absorption (UV–vis), X-ray diffraction (XRD), and field emission scanning electron microscope (FESEM). The UV–vis results indicated that galactose was the most efficient reducing agent. The broadest peak recorded by the rGO-Ag reduced with galactose [rGO-Ag (Gal)] at 271 nm, while the narrowest peak observed at 423 nm corresponded to the formation of silver nanoparticles (AgNPs) on the rGO. The nanohybrids procured with the other reducing agents were also evaluated with XRD. The oxygen and carbon compositions of the samples were also analysed via FESEM equipped with energy-dispersive X-ray (EDX). The average particle size calculated based on the rGO-Ag (Gal) XRD results was the smallest (6 nm) compared to the other two monosaccharides. Furthermore, the d-spacing of the rGO-Ag (Gal) was almost identical to the XRD data, confirming the high-resolution transmission electron microscopy (HRTEM) findings. Consequently, galactose was the ideal reducing agent to synthesise rGO-ag nanohybrids.

AbstractThe hybrids of phthalocyanines with carbon nanotubes, graphene and graphene oxide were demonstrated previously to be promising for different catalytical, electrocatalytical and other applications. Nevertheless, the above carbon nanomaterials are toxic and relatively expensive. We attempted to substitute them by low-cost and harmless graphite, using dry ball-milling of graphite–phthalocyanine mixtures under mild conditions. According to scanning electron microscopy imaging and powder X-ray diffraction, the composites obtained exhibit the absence of crystalline phthalocyanine phase, which implies high efficiency of phthalocyanine milling. According to Raman spectroscopy data, the mechanochemical treatment does not provoke the formation of large amounts of defects in graphite, but instead helps its exfoliation. The composites were characterized by UV-visible spectroscopy and thermal gravimetric analysis, which showed that all of them exhibit a reduced thermal stability compared to unprocessed graphite by roughly 100–250 °C. The strength of interaction of phthalocyanines with a graphene sheet (as a graphite surface model), geometries and selected electronic parameters (frontier orbital and spin density distribution, HOMO-LUMO gap energies) of the resulting noncovalent complexes were analyzed at the PBE-D2/DNP theoretical level. The interactions of phthalocyanines with the graphene sheet are strong, with the calculated formation energies (absolute values) for the noncovalent complexes of 62.1–70.1 kcal/mol.

AbstractBentonite has been an essential component of geosynthetic clay liners due to its low hydraulic conductivity, which has been used as a barrier against hazardous pollutants in landfills. During the drying and wetting processes caused by high temperatures and leachate in landfills, the hydro-structural characteristics of bentonite vary as the moisture content change. This article investigates the effect of dry density and multi-walled carbon nanotubes (MWCNTs) content on the soil shrinkage characteristic curve (SSCC), the soil free-swelling characteristic curve (SFSCC), the soil water characteristic curve (SWCC), and microstructure of bentonite during the drying and wetting processes. Experimental results indicate that the addition of MWCNTs can slow down the volume variation of bentonite at the normal shrinkage stage and at the initial swelling stage and improve the water retention capacity in the low suction range. Meanwhile, reducing bentonite’s dry density can increase the void ratio during drying, decrease the void ratio during wetting, and improve the water retention capacity in the low suction range. Dry density and MWCNTs content both have no influence on the SSCC at the residual shrinkage stage and the zero shrinkage stage, the SFSCC at the residual swelling stage, and the SWCC at the high suction range.

AbstractHighly dispersed fluorinated SWCNTs of submicron length were prepared, characterized and tested as nonvolatile additive to the active layer of polymer/fullerene organic solar cells. Two types of initial SWCNT materials – TUBALL® (OCSiAl) and Super purified plasma tubes (Nanointegris Inc.) – were used. The absence of big CNT aggregates was revealed by atomic force microscopy. The absence of metallic SWCNTs is confirmed by optical spectra of fluorinated SWCNT dispersions. Reproducible increase of the main performance parameters of solar cells (short circuit current, open circuit voltage, fill factor and power conversion efficiency) was obtained upon admixing a small amount of fluorinated SWCNTs (less than 1% weight) into the polymer/fullerene active layer, with either P3HT or PCDTBT donor and either PC60BM or PC70BM acceptor for both direct and inverted device architectures. Since effective charge mobility did not change upon fluorinated SWCNT admixture, the improvement of solar cell performance is not related to SWCNT-induced modification of the electronic structure of the active layer components or charge transfer via fluorinated SWCNTs. Presumably, the origin of this improvements is geometric optimization of the active layer morphology (improving connectivity of donor and acceptor domains) by fluorinated SWCNTs due to their high aspect ratio.

AbstractThis study aimed to determine the effects of varying Aluminum oxide (Al2O3) and Graphene Nanoplatelets (GNP) concentrations on epoxy-based polymer composites’ mechanical and tribological characteristics. Al2O3 (1 to 5 wt.%) and GNP (0 to 1 wt.%) reinforced epoxy matrix composites were produced with sonication and stirring magnetic route. Mechanical, microstructural and tribological properties of composites were investigated via X-ray diffraction (XRD), Archimedes’ Method, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), Raman spectroscopy, hardness, impact, tensile, compressive and wear tests. The highest ultimate tensile strength and compressive strength were found at 62.83 and 137 MPa for 3 wt.% reinforced Al2O3 epoxy matrix composites, and it was observed that there was a 38% and 17% increase compared to neat epoxy, respectively. The highest impact strength was found for 3 wt.% Al2O3 and 1 wt.% GNP-reinforced composites and increased by 19% compared to neat epoxy. The best hardness was found for 3 wt.% reinforced Al2O3 and 0.25 wt.% GNP-reinforced composite, and there was a 22% increase in hardness compared to neat epoxy. Also, the highest wear resistance (1.686x10−6 mm3/Nm) and lowest Coefficient of Friction (COF, 0.13755) were determined for the same specimen.

AbstractThis study consists of the thermal activation of Chlorella vulgaris and Spirulina platensis microalgae with a potassium hydroxide (KOH) chemical agent in a carbon dioxide (CO2) atmosphere and the formation of nitrogen and oxygen-doped material from the hydrothermal interaction of the obtained activated carbons with nitric acid. The obtained nitrogen and oxygen-doped activated carbons were used in the production of electrochemical super capacitors. The morphological properties of the obtained pores were evaluated by transmission electron microscopy (TEM). Electrochemical properties were evaluated according to the cyclic voltammetry (CV) method in sulphuric acid (H2SO4), potassium chloride (KCl), and sodium hydroxide (NaOH) electrolytes with a scanning rate in the range of 2.5–50 mVs−1. Nitrogen and oxygen doped electrode electrochemical capacitor based on Spirulina platensis microalgae showed the highest specific capacitance of 99.53 Fg−1 at a scanning rate of 2.5 mV s−1 in 1 M H2SO4 electrolyte. In contrast, the supercapacitor based on an activated carbon electrode from Chlorella vulgaris microalgae showed the highest specific capacitance of 156.04 Fg−1 at a scan rate of 2.5 mV s−1 in 1 M KCl electrolyte.

AbstractIn this work, the Fe3O4-carbon black filler was obtained from an in-situ coprecipitation method followed by the modification of the heptadecafluorodecyltrimethoxysilane and the Fe3O4-carbon black/poly(vinylidene fluoride) (PVDF) composites with enhanced properties were prepared by a simple solution blending-water precipitating method. The Fe3O4-carbon black distributed well in the PVDF matrix, which was confirmed by the SEM. According to the results of FTIR and WAXD, a lot of useful polar crystalline phases of PVDF formed in the Fe3O4-carbon black/PVDF composites. The electrically conductive ability, the dielectric permittivity, the dielectric loss factor, and the magnetic saturation value of the Fe3O4-carbon black/PVDF composite increased with the increasing loading amount of Fe3O4-carbon black filler. Especially, when the Fe3O4-carbon black was 5 wt.%, the dielectric permittivity of Fe3O4-carbon black/PVDF composite reached as high as 23.5 at 1000 Hz with a relatively low dielectric loss factor value of 0.38 and a magnetic saturation value of 0.64 emu/g.

AbstractUnderstanding the mechanisms of conductivity in disordered carbon materials is one key to creating applied materials based on them. We present a new promising approach to quantitatively assessing the effect of structural parameters on the conductivity of disordered sp2 carbon materials within the framework of a simplified current tube model. Stacks of graphene layers of complex shape and chaotic in contacts as an aggregate of sequentially located and parallel tubes were presented. This approximation made it possible to obtain a reliable quantitative estimate of the influence of the stacks size of graphene layers and their size distribution, as well as the size of the gaps between the stacks on the conductivity. The theoretical positions of the model were tested using the experimentally obtained parameters of the structure of two typical natural disordered carbon materials (shungites).

AbstractA template method for synthesis of B-doped graphene-like carbon nanomaterial (B-graphene-like carbon) with high surface area has been developed. In this method, magnesium oxide is used as a template where a carbon layer doped with boron atoms is deposited. Magnesium oxide carbonization was performed in an autoclave at 600 °C and 5 atm pressure using phenylboronic acid (FBA) dissolved in an ethanol-acetone mixture. Then, magnesium oxide from the С—B/MgO composite was dissolved in hydrochloric acid. The obtained B- graphene-like carbon was studied by IR spectroscopy, electron microscopy, XPS methods and quantum chemical calculations. B-graphene-like carbon contains 3–6 carbon layers and 0.2 wt% B. Structure of carbon net with embedded boron fragment has been proposed as the result of performed studies.

AbstractThe simple method of preparation of highly stable and purified C70 fullerene aqueous solution (C70FAS) is proposed. The features of structural stabilization of C70 fullerenes in an aqueous solution by studying their structural and optical properties using Raman, photoluminescence, infrared reflection-absorption, UV–VIS absorption, and dynamic light scattering spectroscopy methods were analyzed. The experimental results showed that the most likely mechanism for C70 fullerenes stabilization in water is surface hydroxylation with covalent attachment of water hydroxyls to C70 fullerene carbons. Raman and infrared absorption spectra of C70FAS showed characteristic vibrational bands of C70 fullerenes with a slight broadening and low-frequency shift of ∼1 cm−1, indicating the attachment of water hydroxyls to the C70 fullerene carbons. The photoluminescence spectra showed excitonic emission bands of C70 molecules with intensity depending on their content. UV–VIS absorption spectra demonstrate the absorption bands typical for monomeric C70 fullerene. Finally, the dynamic light scattering data confirmed that C70FAS is a typical colloidal fluid containing both individual C70 molecules and their nano aggregates up to 100 nm. These findings provide insights into the stabilization mechanism of C70 fullerenes in water and may have implications for their potential application in nanobiotechnology.

AbstractThe combination of boron and sulfur incorporated reduced graphene oxide (B/S-rGO) was synthesized by a simple hydrothermal technique using a novel and single source of thiophene-2 boronic acid pinacol ester. Structural and functional groups of the synthesized materials were analyzed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis. The Raman analysis revealed the defective structure after incorporating sulfur and boron elements into rGO. The morphological and the presence of elements in the synthesized material were analyzed by scanning electron microscopy, transmission electron microscopy and elemental mapping analysis. The chemical states and chemical composition of B/S-rGO were observed by X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical performance of the prepared material was studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance analysis. GCD studies were performed for B/S-rGO electrode material in an aqueous 1 M H2SO4 electrolyte. The prepared material showed a high specific capacitance of 345 Fg−1 at 1 Ag−1 in a three-electrode configuration. B/S-rGO based device exhibited 97 Fg−1 of specific capacitance at 1 Ag−1 in a symmetric two-electrode configuration. B/S-rGO based symmetric device showed a high energy density of 13.4 Whkg−1 at 249 Wkg−1 and more than 96% capacity retention after 5000 cycles.

AbstractMagnetic graphitized materials were synthesized in the temperature range T = 600–1000° With the method of single-stage pyrolysis of microcrystalline flax cellulose (MCC) modified with citric acid and homogeneously impregnated with FeCl3. The modification of the MCC with citric acid and the use of FeCl3 as a graphitization catalyst reduces the graphitization temperature from 800 to 600 °C and increases the degree of graphitization to 95%. Morphological and physicochemical properties of carbon composites were studied by scanning electron microscopy, infrared spectroscopy with Fourier transform, low-temperature adsorption-desorption of N2, X-ray diffraction analysis and zeta potential. A possible mechanism of pyrolysis of the cellulose matrix has been established by thermogravimetry. The carbon composite obtained at 700 °C has the highest adsorption capacity of the dyes methylene blue (МВ) and methyl orange (МО) was 127.4 mg/g and 23.7 mg/g, respectively. MO molecules have a monolayer character of the adsorbent surface coating, and for MВ, the character of the adsorbent surface coating depends on the pyrolysis temperature. It is established that the physical adsorption of dyes is due to the interaction between delocalized graphite π-electrons and free electrons in the aromatic rings of dye molecules, electrostatic and adsorption interactions. The resulting composites may be potential candidates as dye adsorbents for wastewater treatment.

AbstractReduced graphene oxide (rGO) is added to TiO2 and TiS2 to develop several hybrid electrode materials, including rGO/TiO2, rGO/TiS2, and rGO/TiO2/TiS2 to enhance the electrochemical performance. SEM/EDX, TEM, XRD, XPS, and Raman techniques are used to study the resulting hybrid electrode materials. The capacitance and cycling capacity of the synthesized rGO/TiO2, rGO/TiS2, and rGO/TiO2/TiS2 electrode materials are assessed using galvanostatic and cyclic voltammetry testing. The rGO/TiO2/TiS2 exhibits higher electrochemical performance (726 mA h/g) at 20 mV/s, among the investigated composites. The rGO/TiO2/TiS2 electrode was found to have Rct value of 20.4 Ω.cm2. These values indicate that the rGO/TiO2/TiS2 has a much lower resistance, which may be the primary cause of the outstanding electrochemical properties of the rGO/TiO2/TiS2. The retention capacity of 97.93% at 1 A/g upto10,000 cycles shows that this rGO/TiO2/TiS2 hybrid electrode also exhibits good cycling stability. The rGO/TiO2/TiS2 composites’ respective energy and power densities are determined to be 682 Wh/kg and 5073 W/kg. Due to the synergistic interaction between TiS2, rGO, and TiO2, the rGO/TiO2/TiS2 hybrid is demonstrated to be a superior anode material in supercapacitors. Therefore, the newly fabricated rGO/TiO2/TiS2 nanocomposite could be used as the potential material for energy storage applications.

AbstractNi-Zn ferrites have important applications in the field of soft magnetic materials due to their excellent magnetic properties, but their high bulk density hinders their widespread use. CNT/nickel-zinc ferrite (CNT/Ni0.5Zn0.5Fe2O4) nanocomposites was prepared by sol-gel method, and sintered at 1000 °C to be used as an electromagnetic wave absorber. The results showed that the morphology, impedance matching, density, electrical conductivity and absorption coefficient of CNT/Ni-Zn ferrite was controlled by the additional CNT content. The NZ3 sample containing 0.06 g of CNT showed high conductivity, and high absorption coefficient. The amount of 0.06 g of CNT was a critical amount for the CNT/Ni-Zn ferrite nanocomposites. Above this value, the increasing trend toward improved nanocomposite properties due to the agglomeration of CNTs was reversed. The absorption performance of the CNT/Ni-Zn ferrite nanocomposites are attributed to the incorporation of dielectric and magnetic loss mechanisms in which the magnetic portion is comparable to the dielectric portion. Possessing excellent magnetic and absorption properties, it has the potential to be an excellent electromagnetic wave absorbing material.

AbstractAn effective and green method including in-situ solvothermal reduction of multi-layered graphene oxide (MLGO) using a mixture of acetonitrile and sesame, ginger and cinnamon oils, was investigated for preparing a hydrophobic and corrosion-resistant epoxy coating. The efficiencies of the oils as green reducing agents with synergistic effect by acetonitrile in the solvothermal reduction of MLGO at a temperature of 70 °C were compared with each other. FT-IR, TGA, Raman, and Mapping-EDAX analysis showed that the solvothermal reduction process of MLGO in acetonitrile/cinnamon oil mixture was successfully performed. The results of long-term salt spray and electrochemical impedance tests showed that epoxy-RMLGO (acetonitrile/cinnamon oil) nano-coating had a significant improvement in corrosion resistance (after10 months, the impedance value was 8.1 × 108 Ω cm2) compared with the other coatings. Also, the value of the water contact angle for the nano-coating was 102.80° and based on Mapping-EDAX analysis, the C/O ratio was 54.45.

AbstractThe thermal decomposition of C60Br24•2Br2 has been studied by Differential Scanning Calorimetry (DSC) at different heating rates. Depending from the heating rate, the thermal decomposition peak occurred between 163 °C and 201 °C with an activation energy E# = 108.6 kJ/mol. The decomposition products are C60 (assessed by FT-IR) and molecular bromine. From the decomposition enthalpy measured by DSC, the enthalpy of formation ΔHf°(C60Br24(c)) = 2114 ± 34 kJ/mol has been determined. By group increment or group additivity method ΔHf°(C60Br24 (g)) = 2184 kJ/mol has been calculated, in fair agreement with the experimental value. Furthermore, through the group increment method ΔGf°(C60Br24 (g)) = 3264 kJ/mol has been estimated. The enthalpy of the C-Br bond in the C60Br24 molecule was found comprised between 108 and 120 kJ/mol.

AbstractA novel adsorbent was prepared through a facile layer-by-layer method and was utilized for the removal of heavy metal ions. Firstly, highly crystalline α-ZrP nanoparticles were synthesized and then exfoliated into single-layer nanosheets. The extremely thin nanosheets were uniformly deposited on the surface of cotton through a simple layer-by-layer method with various layers. The resultant adsorbents were applied for the adsorption of Cu2+, Ni2+ and Cd2+ in different conditions and the results showed that the adsorbent performed the best at pH 5 when one layer was deposited. The O-ZrP1@C mixture exhibited the highest adsorption capacities of all, with 83.75 mg/g for Cu2+, 29.16 mg/g for Ni2+ and 55.66 mg/g for Cd2+. The results showed that the experimental data were fitted in pseudo-second-order kinetic model and Langmuir isotherm model. The results indicated that the ZrP-cotton mixture would be a promising candidate for practical application in the treatment of wastewater contaminated with heavy metal ions.