Journal of Nano Research Vol. 71

Abstract: In this study, the synthesis and analysis of the crystal structure of silver nanowires (AgNWs) have been performed using the polyol method. In this research, materials used as the main raw material were silver nitrate (AgNO₃). Polyvinyl pyrrolidone (PVP) was used as a capping agent and stabilizer, and Iron (III) Chloride (FeCl₃) for controlling the shape and size of AgNWs. AgNWs were synthesized using two different solvents i.e., ethylene glycol (EG) and propylene glycol (PG). The crystal structure of AgNWs was analyzed using X-ray diffraction (XRD) with a scanning 2θ in the range of 20° to 90°. Furthermore, the structure and electron diffraction patterns were analyzed using transmission electron microscopy (TEM). The XRD pattern of the AgNW sample also has five diffraction peaks, these five diffraction peaks were identified at 38.24°, 44.42°, 64.54°, 77.52°, and 81.68° representing lattice constants (111), (200), (220), (311), and (222), respectively. Based on the results of the calculation of lattice constant values of AgNWs-EG and AgNWs-PG were 4.084 Å. The TEM images of AgNWs-EG have a diameter of 84 to 133 nm, corresponding to the SEM calculation data having a diameter of 109 ± 22 nm. AgNWs-PG has a diameter of 84 to 264 nm. The study results revealed that the results of the characterization performed are interconnected. The XRD characterization results revealed that both samples were crystal-indexed. AgNWs-PG has a larger crystal size than AgNWs-EG.

Abstract: Heterojunction semiconductor photocatalysis is an auspicious technique for clear up organic pollutants from water, and have been of valuable strategy in the area of photocatalysis. Herein, electrophoretic deposition procedure was used to prepare α-Bi₂O₃/CdS type-Ⅱ heterojunction photocatalysts. The results of PL, Raman, and EIS show that there is a heterojunction effect in α-Bi₂O₃/CdS, which is propitious to improve the separation efficiency of photogenerated electron-hole pairs. The DFT calculation reveals that the work function of CdS (4.57 eV) is higher than that of α-Bi₂O₃ (3.37 eV), which facilitates the migrating of e^- from the CB of α-Bi₂O₃ to the CB of CdS, and the migrating of h⁺ from the VB of CdS to the VB of α-Bi₂O₃, thus the e^--h⁺ pairs with high redox ability are retained. The performances were assessed by degrading methyl orange (MO), acid magenta under simulated visible light irradiation. Under simulated visible light irradiation, BC45 composite exhibited the highest degradation efficiency of 87% (MO) and 81% (acid fuchsin) for 4 h, which was about 2 times higher than that of CdS (MO) and (acid fuchsin). It is believed that the dual characteristics of H₂O wettability and dye adsorption performance in α-Bi₂O₃/CdS composites promote photocatalytic process compared with single CdS and α-Bi₂O₃. The study could provide new insights to develop efficiently capable photocatalysts of the α-Bi₂O₃/CdS composites.

Abstract: This study aimed to investigate the effect of using chitosan polymeric nanoparticles (CNPs) on improving the efficiency of hydroalcoholic extract of Thymbra spicata (TS) on the growth parameters of rainbow trout (Oncorhynchus mykiss) fed with the experimental diets containing different levels of TS extract with and without CNPs. Thymbra spicata loaded chitosan polymeric nanoparticles (TSCNPs) were prepared by ionic gelation methods in the presence of sodium tripolyphosphate (TPP). The fourier transform infrared spectroscopy (FT-IR) of TSCNPs showed that the strong peaks due to hydroxyl groups (OH) and alcohol and amine (NH) were shifted to 3427 cm⁻¹, and peak wide has expanded due to increased hydrogen bonds. The FT-IR results were proved the interaction of CNPs and TS extract. The scanning electron microscope (SEM) imaging showed a spherical shape, smooth and homogeneous structure for nanoparticles. In zetasizer results, nanoparticles size average, poly dispersity index (PDI), zeta potential (ZP), and zeta average (d.nm) were 86.1 nm, 0.21, 31.3 mV, and 83.3, respectively. In energy dispersive spectroscopy (EDS) results, the major compounds of TSCNPs included C, O, Al, Cl, Mg, K, and Ca. At the UV-Visible spectrum, the absorption of TS extract based on the absorption of flavonoids was observed at 430 nm. Obtained results showed that the encapsulation efficiency (EE) of the nanoparticles was 94.1%. In vitro, a gradual and acidic dependent period of 120 h was observed in TS release conditions. After eight weeks of feeding, the addition of 400 mg kg^-1 diet of TSCNPs resulted in significant improvement in the final weight, final length, specific growth rate (SGR), and survival (S) (P < 0.05). This research suggests that loading Thymbra spicata hydroalcoholic extracts on chitosan polymeric nanoparticles increased the efficiency of plant extract compared to extract pure form and improved the growth performance in rainbow trout.

Abstract: In the present work, double layer Zinc Oxide (ZnO) nanorods (NRs) were fabricated hydrothermally and their photoluminescence (PL) properties were investigated. Two different recipes and their combination were used to obtain double layer vertically well-aligned ZnO NRs. These recipes include polyethylenimine (PEI) and citrate as additives in the growth solution resulting long NRs with a broad defect emission and relatively short NRs with a near band-edge ultraviolet (UV) emission, respectively. Double layer growth of long-long (LL), long-short (LS) and short-short (SS) ZnO NRs were considered. Grown samples were annealed in a forming gas atmosphere for a better quality NR structure. LL ZnO NRs (long ZnO NRs grown on a long ZnO NR layer) with a 65 µm thickness showed a broad yellow-orange PL emission and no any near band-edge UV emission was observed. LS ZnO NRs representing short ZnO NRs grown on a long ZnO NR layer (LS1= 36 µm, LS2= 48 µm and LS3= 44 µm) showed an enhanced near band-edge UV emission when compared to that of the long ZnO NRs. The UV intensity was found to decrease with the increase in thickness of the NRs in LS samples. Finally, SS ZnO NR sample, (short ZnO NRs grown on a short ZnO NR layer) which has a thickness of 33 µm, displayed a stronger near band-edge UV emission with a negligible broad emission than that of as-grown SS ZnO NRs (UV peak intensity ratio 59). This study should be important for applications where longer NRs with enhanced PL properties are strictly required.

Abstract: Abstract Reduced graphene oxide (rGO) is one of the promising materials which are used in energy storage devices, field effect resistors and as an additive in polymer composites for functional and structural applications. The reduction of graphene oxide (GO) to rGO is popular and attractive. Chemical reduction of GO is considered as one of the promising methods for the large-scale production of rGO. Herein, we report for the first time a sustainable, eco-friendly and facile approach for synthesizing rGO using cashew apple extract as a reducing agent. Reduction of GO by cashew apple extract was confirmed by the bathochromic shift in the UV-Visible spectrum. The extent of reduction by cashew apple extract at temperatures (80°C, 120°C, and 180°C) was determined by making use of X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) and were morphologically confirmed using Transmission Electron Microscopy (TEM). Through this research work, we propose an environment friendly approach for the production of rGO.

Abstract: Recently, perovskite nanocomposites have attracted much ‎attention as active layers due to the relatively high stable efficiency of solar cells based on them. In this ‎paper, we study perovskite nanocomposite layers based on ‎semiconductive/nonconductive molecules or polymers, their deposition methods, properties, and ‎influence on the device performance. We have found that the quality of the ‎perovskite layer (morphology and crystallinity, cross-linked grains, trap states density, as well as ‎conductivity and charge carrier mobility) is strongly affected by various factors ‎related to the additive: such as type (i. e. semiconductive or nonconductive, ‎molecule or polymer), chemical structure (backbone length and ‎molecular weight, functional groups, π system, side chains, donating atoms and basicity), amount,‎ solubility, conductivity, photoactivity, polarity, hydrophobicity, and addition methods. Due to the small amounts added, these additives can lead to slight changes in energy levels, bandgap (E_g), and light absorption ‎properties. Ultimately, using the suitable deposition method and additive at an optimal amount can ‎greatly improve the stability and efficiency of the devices and reduce ‎hysteresis.

Abstract: In this study, the α and β modifications of MnO₂ have been successfully synthesized by the hydrothermal method. The obtained materials have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-temperature nitrogen adsorption. In addition, the supercapacitor performance of the materials has been pre-tested to assess their suitability for practical applications. The average particle size of the α modification is 12-15 nm, and the β modification is 14-18 nm. The surface areas of the α and β modifications of MnO₂ are 200 m²/g and 70 m²/g, respectively. The average pore sizes are 3.2 nm and 5.3 nm, respectively. The specific capacitance of 40 F/g is observed at 1 mV/s, which has been recorded using cyclic voltammetry and constant current charge-discharge cycling in 30 % aqueous KOH solutions. It has been determined that the specific capacitance of the β - MnO₂/electrolyte system decreases from 40 F/g to 15 F/g with an increase in the scan rate from 1 to 30 mV/s. In addition, the total capacitance of the material was divided into the electric double layer capacitance and the diffusion-controlled redox capacitance due to the Faraday reverse redox reactions. Finally, the pseudocapacitance contribution has been determined to be 90 % of the total specific capacitance.

Abstract: Flower-like TiO₂ hierarchical structures were synthesized by a solvothermal strategy using tetrabutyl titanate as the titanium source. The obtained flower-like TiO₂ hierarchical structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), specific surface area analysis, Raman spectroscopy and energy-dispersive spectroscopy (EDS). Results show that the flower-like hierarchical structures are composed of anatase titanium dioxide. TiO₂ nanowires are first formed by the self-assembly of nanocrystals with a diameter of 20 nm, and then several TiO₂ nanowires produce a petal-like structure. Finally, flower-like TiO₂ hierarchical structures with a diameter of 2 ~ 2.3 μm are assembled by these petal-like structures. The electrochemical properties of the flower-like TiO₂ hierarchical structures were studied by using these hierarchical structures as the anode material in a lithium-ion battery. The flower-like TiO₂ hierarchical structures have an initial discharge capacity of 473.9 mAh/g at a current density of 100 mA/g and an initial discharge capacity of 244.4 mAh/g at a current density of 2 A/g in the potential range of 0.01~3 V. The photocatalytic properties of the flower-like TiO₂ hierarchical structures were studied by degrading methyl orange (MO) solution under ultraviolet (UV) light irradiation. When used as a photocatalyst, the degradation rate of MO is 95.8% after 40 min of UV irradiation, showing that the flower-like TiO₂ hierarchical structures have excellent photocatalytic activity.

Abstract: Polymer insulators traditionally used in HVAC (High Voltage Alternating Current) are used in HVDC (High Voltage Direct Current) transmission lines. For these polymer insulators, silicone insulating rubber, based on Polydimethylsiloxane (PDMS), is used in industry to manufacture high voltage insulators for power lines. Silicone rubber material ages due to pollution and environmental factors such as UV (ultraviolet light), rain, and temperature. Moreover, no international standard is available to standardize its functional characteristics to ensure its best performance in HVDC regime. Standards usually define the testing procedures to measure the resistance of the materials to these conditions. One of the tests used to evaluate the performance in AC (alternating current) of the housing material of polymeric insulators is the inclined plane test (IPT). This test has the purpose of assessing the tracking and erosion resistance of housing materials. However, for the IPT, no consensus is reached yet for this testing in Direct Current (DC) voltage. In addition, there are no indications whether the formulations that have been successfully used for HVAC work fine; also, in HVDC regime, or not. In this paper, an investigation of the tracking and erosion resistance under positive DC IPT is presented. In this way, the study was carried out on skirts of an HVAC commercial insulator and samples of a new outstanding composite silicone rubber formulation filled with micro and nano particles. The results show that HVAC silicone rubber formulations could not be suitable for HVDC applications under highly polluted conditions. In the case of the new enhanced composite, it is shown how nano particles used in this material significantly enhance the performance during DC tracking and erosion testing well above other materials tested in previous works. Also, thermogravimetric analysis (TGA) of the composites is used to correlate thermal stability with the DC IPT performance.

Abstract: To achieve higher thermal electric and mechical properties in non-polar thermoplastic vulcanizate (TPV), multi-walled carbon nanotubes (MWCNTs) as reinforcing nanofiller to prepare TPV/MWCNTs conductive elastomer composites by dynamic vulcanization. The thermodynamic calculation indicates that MWCNTs have a tendency to preferentially localize at the two-phase interface of PP and IIR during melt-blending processing. The morphology of TPV/MWCNTs composites elucidated from TEM micrograph exhibited that the IIR domains dispersed in the PP matrix, and most MWCNTs were dispersed at the two-phase interface and PP phase, which is mainly due to the effect of kinetic factors. When the MWCNTs content reached the percolation threshold (3 wt%), the network structure of MWCNTs was formed, the ac conductivity and dielectric permittivity increased sharply. Compared with pristine TPV, the thermal conductivity of TPV/MWCNTs composites increased 39.7 %. The MWCNTs can combine to the IIR network during dynamic vulcanization, and enhances the interface interaction of MWCNTs and TPV matrix, which is improve the tensile strength of TPV/MWCNTs composites.