Narrow Results

The recent progress in nanofiber research has demonstrated the potential for improving the physical properties of materials through the integration of graphene nanoplatelets (GNP). This study involves the synthesis and characterization of novel GNP-infused polyvinylpyrrolidone (PVP) electrospun nanofibers. The required precursor solution was prepared using dimethylformamide (DMF) as a solvent, and that included 1.5wt.% concentrations of GNP with 20 wt.% of PVP in 10mL of DMF solution. The investigation using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the morphology of the fibers with the distribution of graphene nanoplatelets. The zeta potential analysis demonstrates that the GNP/PVP nanofibers exhibit significant stability across a wide pH range, particularly in highly acidic and basic conditions. The thermogravimetric analysis (TGA) analysis showed exceptional thermal stability, with minimal weight loss until 300–400${}^{\circ }$C. The degradation of the PVP matrix was observed beyond 400${}^{\circ }$C. The results of the study show that GNP/PVP nanofibers have significant potential for specific applications in thermal management and energy storage under controlled temperature conditions.

This paper reports that ZnSnO nanofibers (ZSNFs) were synthesized by thermal oxidation of ZnSn alloys. ZnSn alloys were prepared by cold press and sintering (powder metallurgy). The structure and optical properties were characterized by X-ray diffraction (XRD), micro-Raman scattering technology, field emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectrum. The micro-Raman scattering spectra of ZSNFs show four Raman peaks at 574, 1156, 1729 and 2330 cm^-1. The diameter and length of ZSNFs are about 50 nm and 60 μm, respectively. The room temperature PL spectra of ZSNFs shows the near-band-edge emission at ~391 nm and a broad green emission at ~493 nm.

Aqueous silk fibroin (SF) sol is a colloidal solution. With the colloidal hydration layer and electrostatic repulsion, the SF sol can hardly make the efficient collision/assembly among micelles and perform like a following sol for a long time. In this paper, hydrophilic silk-based sequences (HSF) derived from SF molecules were obtained by immersing the dried SF condensates with water and extracting the dissolving fraction. The HSF was obtained by immersing the SF condensate dried at the temperature of $20$–$25^{\circ }\mathrm{\text{C}}$ and relative humid of 55–60% in water and collected the lixivium. The dissolving ratio was about 30%. The HSF sol (0.5%, w/v) self-assembled into the mesoscopic 3D nanofibrous network within 8 h. The obtained HSF nanofibers were 10–100 $\mu \mathrm{\text{m}}$ in length and 50–100 nm in diameter. The HSF nanofiber possesses similar hierarchical structure consisting of nanofibrils bundles to the native silk fiber. There were significant aggregation structure transitions from random coil to $\beta$-sheet and amorphous chains to Silk II crystal aggregation during the formation of HSF nanofibers. The HSF nanofiber holds the potential to give further insight into the reconstruction of native silk in vitro and the fabrication of tough silk-based biomaterials.

The properties of nanomaterials usually depend on their microstructures, the same material of different microstructures could be used for various applications. However, most devices could only synthesize a single microstructure, so it is meaningful that the different microstructures were synthesized by one method. In our study, electrospinning was applied to fabricate ZnO nanofibers and nanoparticles. In this approach, Zn(Ac)/PVP composite fibers of different component ratio were synthesized by electrospinning method which was subsequently calcined and formed ZnO nanofibers and nanoparticles. The microstructure, chemical composition and gas sensing were investigated with scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and WS-60A gas sensing measurement system. The synthesis mechanisms of ZnO nanofibers and nanoparticles were discussed in detail.

In this article, the space-time fractional perturbed nonlinear Schrödinger equation (NLSE) in nanofibers is studied using the improved $tan(\varphi (\xi )/2)$ expansion method (ITEM) to explore new exact solutions. The perturbed nonlinear Schrodinger equation is a nonlinear model that occurs in nanofibers. The ITEM is an efficient method to obtain the exact solutions for nonlinear differential equations. With the help of the modified Riemann–Liouville derivative, an equivalent ordinary differential equation has been obtained from the nonlinear fractional differential equation. Several new exact solutions to the fractional perturbed NLSE have been devised using the ITEM, which is the latest proficient method for analyzing nonlinear partial differential models. The proposed method may be applied for searching exact travelling wave solutions of other nonlinear fractional partial differential equations that appear in engineering and physics fields. Furthermore, the obtained soliton solutions are depicted in some 3D graphs to observe the behaviour of these solutions.

The perturbed nonlinear Schrödinger equation is employed to characterize the dynamics of optical wave propagation when confronted with dissipation (or gain) and nonlinear dispersion that vary with both time and space. This equation serves as a fundamental model for investigating pulse dynamics within optical fibers and has application to nanofiber applications. This study successfully discovers optical solitons within this framework using the unified solver, Jacobi elliptic function, and simplest equation methods. We extract solutions using hyperbolic, trigonometric, and rational functions, including multi-solitons, dark, singular, bright, and periodic singular solitons. This study thoroughly compares our results with existing literature to provide novelty and significance of our findings. We have incorporated a detailed comparison between the methods employed in our study, which highlights their importance and strength. We have derived soliton solutions for the examined equations and generated 3D contour and 2D visual representations of the resulting solution functions. Alongside obtaining the soliton solutions, we offer a graphical exploration of how the parameters in the considered equations influence the system.

ZnO:Co thin films were synthesized by the chemical spray pyrolysis (CSP) on glass substrates. Then, investigated the impact of Co doping concentration on its physical properties. XRD analyses show that all films have a polycrystalline structure of hexagonal ZnO. The crystallite size increased from 18nm to 25nm with Co doping concentrations. Furthermore, the unit cell volume increased from 47.485Å to 47.831Å, and the Zn–O bond length expanded from 1.97588Å to 1.98071Å. SEM observations reveal the formation of fiber-like nanostructures in the Co-doped thin films. The diameter of nanofibers increased with Co doping concentration from 260nm to 700nm. The optical characteristics were studied by the UV-Visible spectrophotometer and manifest the optical transparency vary with Co doping. In addition, the band gap decreases from 3.27eV to 2.73eV with increasing Co doping concentrations. The conductivity varied from 3.35S$\cdot$m${}^{-1}$ to 19.88S$\cdot$m${}^{-1}$ with Co doping concentrations. Empirical models were proposed to evaluate the correlated variables with excellent accuracy with the experimental data. The best result was accomplished in ZnO:Co1% films, where good transparency and high conductivity were achieved.

Zinc oxide (ZnO) nanofibers and nanopetals were successfully deposited onto mesoporous silicon (meso-PSi), silicon, and glass substrates using zinc acetate via Spray Pyrolysis method. Electrochemical etching of the P-type (100) silicon wafer was used to prepare the mesoporous silicon layer. The effects of nozzle diameter and substrate type on the morphological, structural, and optical properties were investigated using XRD, SEM, EDX techniques, FT-IR, and UV-Vis spectrometry. Scanning Electron Microscopy (SEM) confirms the meso-PSi morphology with a diameter varying from 20nm to 45nm and illustrates the prepared ZnO nanostructures. EDX results show that the ratio of Zn:O is found to be similar to 1:1 for the 3-mm diameter when the oxygen is much higher than the Zn element in the 18-mm diameter. XRD measurements indicated that all films show a hexagonal Wurtzite structure with a variation of crystallographic properties and orientation according to the prepared morphology. The mean value of the crystallite size is 14.27nm for the 3-mm diameter and 19.01 nm for the 18-mm diameter. The variation in the morphological characteristics of the deposited ZnO leads to a variation in the optical properties of the sprayed ZnO thin films. The layers bandgap energy (Eg) was estimated to be 3.28 and 3.26eV for the ZnO layers prepared by 18-mm and 3-mm nozzle diameters, respectively. This study is also helpful for subsequent studies on the tailoring of morphology and ZnO growth control on PSi substrates.

Cadmium Telluride: Iodine nanoparticle thin films were prepared by spraying iodine doped CdTe nanoparticles dispersed in 1-Butanol, on the glass substrates kept at 200°C for 20 min. Iodine doped CdTe nanoparticles had been prepared by adding trace amounts of Iodine powder in addition to stoichiometric ratios of Cd and Te in the Solvothermal synthesis. The films were prepared by applying without a voltage and with a voltage of 700 V to the nozzle during the deposition. The presence of iodine in the films was confirmed by the sign of voltage generated (positive relative to the cold end) in the hot probe method and also from the elemental analysis using X-ray Photoelectron Spectroscopy. X-ray diffraction patterns of the films showed predominantly Hexagonal CdTe peaks in both the cases. From the transmission spectra of the films the bandgap was found to be 1.77 eV against the bulk CdTe bandgap of 1.5 eV. The band edge was not as sharp as compared to that in case of the undoped films. SEM and TEM micrographs of both the films revealed the formation of Nanofibers.

ZnS nanofibers with lamellar mesostructure could be built up from in situ generated ZnS precursors via hydrothermal routes using neutral n-alkylamines as structure-directing template and ethylene diamine tetraacetic acid (EDTA) as stabilizer. The morphology and structure of the obtained products were thoroughly investigated via scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDX), transmission electron microscope (TEM), X-ray powder diffraction (XRD) and thermal analyses. HRTEM and XRD results revealed that the so-produced nanofibers were lamellar mesostructure and its framework was built of crystalline wurtzite ZnS. It was also found that the distance between the layers was proportional to the chain length of the alkylamine. The UV-visible absorption spectrum showed that the nanofibers exhibited strong quantum-confined effect with a blue shift in the band gap. Finally, a probable mechanism for the assembly of the nanofibers was also proposed.

Ferromagnetic nickel metal beads, fibers, and thin films have been successfully grown from salt solution by a stepwise hydrazine reduction route with and without surfactants. XRD analyses showed that nickel was grown in the metallic phase and no other phases such as nickel oxide were detected in the prepared samples. SEM investigations showed that bead-like structures that agglomerated in the form of cloth- or net-like structures of about 1 μm size that composed of needle-like nanoparticles have been synthesized without using a surfactant. Sharp decrease in size was observed when sodium dodecyl benzene sulphonate (SDBS) and/or polyethylene glycol (PEG) were used. Bead-like morphology of nickel nanostructures of < 150 nm were deposited in this case. Free-standing nickel thin film structures that composed of needle-like nanoparticles of about 50 nm size were deposited by a stepwise reduction. Nickel nanostructures of < 100 nm showed higher coercivity (Hc) value of 184.6,Oe and lower saturation magnetization (Ms) value of 13.29 emu/g. This might be due to the anisotropic shape and size effects. It is strongly believed that nickel nanoparticles are self-assembled through a dipolar–dipolar interaction due to the magnetic property.

Electrospinning is a very simple and versatile process by which polymer nanofibers with diameters ranging from a few nanometers to several micrometers can be produced using an electrostatically driven jet of polymer solution (or polymer melt). Significant progress has been made in this process throughout the last decade and the resultant nanostructures have been exploited to a wide range of applications. An important feature of the electrospinning process is that electrospinning nanofibers are produced in atmospheric air and at room temperature. This paper reviews the assembled polyacrylonitrile (PAN)-based carbon nanofibers with various processing parameters such as electrical potential, distance between capillary and collector drum, solution flow rate (dope extrusion rate), and concentration of polymer solution. The average fiber diameter would increase with increasing concentration of the polymer solution and the flow rate. Therefore, the screen distance could also increase but the average electrical potential of the fibers diameter decreases. Electrospinning process can be conducted at higher electrical potentials, lower flow rate, nearer screen distance, and higher concentrations of dope.

Fabrication of Nanogenerators (NGs) using Electrospun polyvinylidene fluoride (PVDF) nanofibers for sensing and energy harvesting applications is a trending research due to its flexibility, biocompatibility, low-cost, etc. Different electrode materials, polymer composites had been proposed to increase the energy output. However, the contact area between the electrode material and nanofiber mat which helps to conduct more piezoelectric charges to the electrode surface are still unexplored especially at nanoscale level. In this paper, authors have proposed the use of low-cost carbon conductive paint to increase the contact area between the electrode and nanofiber mat. The electrode material is coated with conductive paint and the NG was fabricated with that electrode to compare the performances with conventional NG. Piezoelectric performance of the proposed NG has increased substantially as it generates an open circuit voltage ${(V}_{\mathrm{\text{oc}}}$) of 4.5V and short circuit current $(I_{\mathrm{\text{sc}}}$) of 25nA, whereas the conventional NG can only produce 1.6 $(V_{\mathrm{\text{oc}}}$) and 1.5nA $(I_{\mathrm{\text{sc}}}$). A drop test experiment was conducted, and the device consistency was verified experimentally.

Nanofibers based on the polymer mixture that was associated with poly(vinyl alcohol) (PVA) and poly(acrylamide) (PAAm) (50/50 wt.%) doped with different ratios of silver nanoparticles (Ag NPs) were successfully synthesized using electrospun method, which was performed at room temperature (RT) and high voltage (12 kV). The products were studied using techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and ultraviolet–visible absorption spectroscopy. SEM results show uniform structures and a smooth surface without particles visible on the surface of the nanofibers. Also, SEM images show that the average diameter of polymer blend nanofibers is 157.40 nm and decreases with the increasing concentration of Ag NPs. The small capacity of the carbonyl group to operate as a powerful electron donor for interacting with ${\mathrm{\text{Ag}}}^{+}$ cation is shown by the fact that the FTIR signal strength decreases with increasing dopant concentration, indicating an increase in the basicity of the major functional groups. The X-ray diffraction pattern results confirm the amorphous nature (nano-crystalline) of the PVA–PAAm. The XRD results show that the crystallite size increases with the increase of the concentration of Ag and the peaks of weak intensity at a concentration of 6% agree with Ag in the cubic structure. Indirect allowed and forbidden transition optical energy gap values decreased with increasing Ag NPs content. The effect of doping on the other parameters (absorption coefficients, refraction index and extinction coefficient) of different blend behavior was investigated in detail which qualifies them for solar cell applications.

The iron (III) oxide nanoparticles (NPs) were prepared by a solvent-controlled method when preparing the electrospinning solution. Nanofibers (NFs) were prepared from pure PVP and PVP doped with ratios 1%wt., 2%wt. and 3%wt. of Fe₂O₃ NPs at room temperature by the electrospinning technique. Optical properties like absorbance and the band energy gap ($Eg$) were studied, and the direct band gap of pure PVP NFs is 4.07eV and decreases slightly with increasing concentration of Fe₂O₃ NPs. The PVP NFs with Fe₂O₃ NPs were used as a UV-Vis light detector with good responsivity and specific detectives at a mixing rate of 3% Fe₂O₃ NPs, which was 12A/W and $27.76\times 10^{12}$ Jones at wavelength 458.3nm, and also had the lowest values for the rise-time and fall-time.

We present here the simple procedure for synthesizing elongated fibers like porphyrin aggregates. Usually whenever the aggregation in dye molecules takes place the emission always tends to quench. In this work we explore and discuss the unusual enhanced emission property of these aggregates. The nanofibers of porphyrin were characterized with the help of atomic force microscopy and UV-vis spectroscopy whereas photoluminescence spectroscopy was used to check their emission property.

The potential utility of electrospun polystyrene (PS) nanofibers embedded with 2,6-diiodo-8-phenyl-1,7-dimethyl-3,5-di-2-thienylvinyleneBODIPY for the photocatalytic degradation of azo dyes is investigated. A comparison of the singlet oxygen quantum yield of the $\pi$-extended BODIPY dye in solution and in the PS nanofibers demonstrates that its photosensitizer properties are retained when it is embedded in the solid phase. The photocatalytic degradation properties of the PS nanofibers for Methyl Orange and Orange G were determined by using a Thorlabs 625 nm light emitting diode. The rate of photodegradation increases with the Orange G and Methyl Orange concentration and follows pseudo-first order kinetics at pH 6.7.

The catalyst-free synthesis of silicon carbide (SiC) nanowires was carried out from polyvinyl alcohol (PVA)/silica electrospun nanofibers at high temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and thermogravimetery analysis (TGA) were employed to study morphology and formation of SiC nanowires. Based on the TGA analysis, the carbon yield was increased when inert gas flow rate and heating rate decreased and polymeric nanofibers has been stabilized. The XRD and TEM results showed that the produced nanowires were crystalline β-SiC and rather homogeneous in thickness with an average diameter around 50 to 70 nm and a length of more than 10 μm. Finally, a possible growth mechanism of β-SiC nanowire based on a vapor–solid (VS) mechanism was proposed.

In this paper, we report a unique growth of nanofibrous structures and nanospheres of titanium using femtosecond laser in air and without the need for any type of catalyst. The femtosecond laser was used to generate nanoparts on a titanium substrate. The irradiated substrate is assumed to be subjected to plane stress type of temperature variation and a new method combining finite difference and Runge–Kutta 4 transient thermal model has been developed to calculate the temperature distribution on the top surface of the substrate during laser ablation. A Matlab code has been developed and validated with the known results from the literature. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffractograms (XRD) and micro-Raman analysis were conducted to characterize the microstructure and revealed metallic and oxide phases in the nanostructure analyses. Results showed that nanofibers and nanospheres were grown in the order of few hundreds nanometers or more. The effect of the laser power on the energy/pulse and hence the temperature was studied. It was found that high temperature results in the formation of nanofibers while lower temperature results in formation of nanospheres. This first time observation could have potential application in biomedical, optoelectronics and photocatalysis.

One-dimensional (1D) CuO/In₂O₃ heterostructured nanofibers with the diameter of about 300 nm were successfully prepared through combining a facile single-capillary electrospinning with sintering process, and investigated by thermogravimetric and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) techniques, etc. The photocatalytic activities were examined by degrading methylene blue (MB) under 500W xenon lamp, halogen lamp and mercury lamp irradiation, respectively. The heterostructured nanofibers exhibited a higher photocatalytic activity than P25-TiO₂ under 500W xenon lamp irradiation due to the enhanced absorption for visible light and the efficient electron–hole separation and transportation. The single CuO microfibers and In₂O₃ nanofibers were also prepared as the control groups by the same method.