International Journal of Nanoscience

This report discusses in detail about the Fire retardant (FR) characteristics of polyvinyl alcohol (PVA) matrix fabricated by impregnating zinc borate nanoparticles (ZB Nps) as FR with trace amounts of copper chloride/aluminum chloride by solvent casting method. ZB Nps prepared by co-precipitation method are characterized using XRD, FTIR, SEM, TEM, etc. XRD pattern revealed the crystal geometry of ZB Nps and SEM and TEM micrographs depict a rod-like structure with 300–400nm size. Appropriate amount of ZB Nps and transition metal salts are mixed with PVA in aqueous medium and thin film samples are obtained by solvent casting method. The vibrational spectra, thermal stability and flammability of the polymeric composites are characterized using FTIR, TG/DTA and Flammability tester, respectively. FTIR spectra confirm the existence of ZB Nps in the prepared polymer composites. TG/DTA studies revealed higher degradation temperature and thermal stability of polymer composite over pure PVA. The limiting oxygen index (LOI) test presented a convincing account about the improved FR nature of obtained polymer nano composite with a significant LOI of 56% compared to virgin polymer which have LOI of 19.6%.

In this study, less expensive mesoporous nano carbon (NC) infused in polylactide (PLA) thermoplastic filaments were fabricated to improve the electrical properties and maintaining sufficient strength for 3D printing. Solution blending was used for PLA-NC nanocomposite fabrication and melt extrusion was employed to make cylindrical filaments. Mechanical and electrical properties of 1–20wt.% of NC-filaments were investigated and significant improvement of conductivity (3.76S/m) and sufficient yield strength (35MPa) were obtained. SEM images exhibited uniform dispersion of NC in polymer matrix and DSC results showed no significant changes in the glass transition temperature ($Tg$) for all the compositions. Perspective uses of this filament are for fabrication of electrical wires in 3D printed robots, drones, prosthetics, orthotics and others.

Mesoporous silica nanoparticles (MSNs) have gained attention worldwide due to their structural versatility for diverse applications in a number of frontier areas of sciences. The intrinsic chemical, textural and structural features of MSNs allow fabricating versatile multifunctional nanosystems. The present review provides an overview of the research progress in artificial and biological production of MSNs, their properties and various applications in cutting edge areas of sciences.

Graphitic carbon-doped silica aerogels, including graphite-doped and graphene-doped silica aerogels, were fabricated by the sol–gel method. Thermal resistance was a significant comprehensive parameter which could reflect the ability to prevent the heat transfer. In order to give a direct evaluation of the thermal insulation performance, the calculated formula of thermal resistance for graphitic carbon-doped silica aerogel thermal insulation layers had been given through theoretic analysis on the basis of the thermal conductivity and the aerogel-based heat insulation layers showed good thermal insulation performance. It was expected that theoretical evaluation and experimental research could provide a reference for the reliability and performance in the field of the aerogel-based insulation layers.

Bismuth ferrite (BiFeO${}_3)$ nanorods have been prepared from 2-methoyethanol (2-MOE)-assisted sol–gel technique. Structure, dielectric, and magnetic properties of BiFeO₃ nanorods are briefly discussed in this paper. Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) results suggest that the BiFeO₃ peaks calcined at 500^∘C exhibit a distorted rhombohedral perovskite structure with the absence of other secondary phases like Bi₂Fe₄O₉. Meanwhile, the BiFeO₃ showed excellent photoluminescence (PL) behavior due to the transmission of electrons from conduction band to the valence band. Ferroelectric hysteresis loop of BiFeO₃ shows an increase of coercivity from 5.5–6$\mu$C/cm² in a frequency range of 6–12kHz. The magnetization measurement resulted in a well-saturated ferromagnetic behavior, and in addition, the temperature-dependent magnetization was discussed for BiFeO₃ nanorod using superconducting quantum interference device (SQUID) method. The zero-field-cooled (ZFC) and field-cooled (FC) curves reveal spin-glass effect owing to size effects, spin exchange, and anisotropy of material assembly.

A facile and easily separated adsorbent, graphene oxide (GO) pellets wrapped by chitosan (GOP) were prepared. Batch adsorption studies were carried out to study the adsorption properties of congo red onto GOP by varying the experimental parameters such as the contact time, the initial concentration of congo red, the solution pH, the adsorbent dose, and the temperature. The kinetic studies showed that the adsorption data fitted a pseudo-second-order model well. The isotherm analysis showed that the adsorption data fitted the Freundlich model well. The adsorption mechanism was mainly attributed to electrostatic interactions, $\pi$–$\pi$ stacking interaction, hydrogen bond, and van der Waals force. Thermodynamic studies indicated that the adsorption process was endothermic and spontaneous.

In the field of nanotechnology, the utilization of nanoparticle (NP) synthesis is of great interest to researchers. Numerous attempts have been made for the green synthesis of silver NPs using plant extracts and some methods have successfully accomplished this. This research focuses on using an eco-friendly method for the green synthesis of silver NPs using six cultivars of Phoenix dactylifera fruit extract and determining their antioxidant and antimicrobial activity. These NPs were then characterized by their optical property using ultraviolet-visible spectral analysis. The surface plasmon resonance for these synthesized NPs was observed at 420nm in the ultraviolet-visible spectra. These NPs were subjected to total antioxidant capacity (TAC), total flavonoid content (TFC), total phenolic content (TPC), 2,2’-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity, ferric reducing antioxidant power for evaluating their antioxidant properties and compared with the results of water extracts of the fruit. The antimicrobial activity was assessed against Staphylococcus aureus and Escherichia coli. Overall, NPs exhibited good-to-moderate antioxidant activity and strong antimicrobial activity. The TAC and TPC of NPs were found to be lower, but TFC was relatively high compared with water extracts. The ferric reducing ability of NPs varied according to the date cultivar and was higher than water extracts in only some date varieties. On studying the antimicrobial activity, NPs showed greater bacterial inhibition than water extracts, and Staphylococcus aureus was more potent than Escherichia coli. The overall findings highlight the potential use of green synthesis of silver NPs for antioxidant activity and particularly antimicrobial activity and may be beneficial for biomedical and pharmaceutical purposes.

A simple green one-step method for the synthesis of highly active palladium nanoparticles embedded on copper oxide as an efficient catalyst for ligand-free Heck and Sonogashira cross-coupling reactions has been developed. The synthetic approach is based on Microwave (MW)-assisted simultaneous chemical reduction of an aqueous solution of palladium and copper salts using hydrazine hydrate as the reducing agent. Selected characterization of the catalyst with transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectroscopy (XRD) reveal a size range of 25$\pm$2nm for the generated catalyst nanoparticles with the highest catalytic activity. The use of the generated Pd/CuO nanoparticles is highly advantageous due to the use of ethanol/water as an environmentally green solvent under mild reaction conditions. Furthermore, the synthesized Pd/CuO nanoparticles catalyst can be recycled and re-used up to five times with negligible effect on the efficiency having turnover number up to 6000 and turnover frequency reaching 72000h${}^{-1}$ for 20wt.% Pd loaded catalyst at 150^∘C.

In this paper, we report the synthesis of Fe₃O₄ nanoparticles which are resistant to surface poisoning, has been adopted. Fe₃O₄ nanoparticles have been successfully coated with Au in the form of a shell with different sizes (Fe₃O₄/Au Core/Shell). Adjustment of the components’ ratio makes the shell thickness of the core/shell particles tunable. Thus, the presented route yields well-defined core/shell structures of different sizes in the range 15–57nm with varying the proportion of Au noble metal to Fe₃O₄ nanoparticles. The UV-Visible absorption spectra, X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) were applied for the characterization of the formed core/shell structures. Moreover, magnetic properties of the core/shell nanocomposites were also studied using Vibrating Sample Magnetometry (VSM).

Nano-sized cobalt oxide particles exhibit unique and fascinating physical, chemical and anti-microbial activity owing to their large surface to volume ratio. The study of metal oxide nanoparticles interaction with pathogenic microorganisms is great importance for various biomedical applications. The main purpose of this work is to study the anti-bacterial and anti-fungal behavior of cobalt oxide (CO₃O₄) nanoparticles against gram-positive and gram-negative bacterial strains and different fungi. The structure and morphology of CO₃O₄ nanoparticles were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and UV-Visible Spectroscopy, respectively. The CO₃O₄ nanoparticles showed a significant anti-bacterial activity against two gram-positive bacteria, Staphylococcusaureus (G$+$), Streptococcus mutans (G$+$), and two gram-negative bacteria, Klebsilla pneumonia (G$-$), E. coli (G$-$), and it shows a good anti-fungal activity against the two different fungal i.e., Aspergillus flavus (F) and Aspergillus niger (F), at different solvents. It was noted that synthesized CO₃O₄ nanoparticles exhibited the solvent-dependent anti-bacterial activity against all tested bacterial strains. CO₃O₄ NPs could be employed effectively for anti-microbial applications.