Current Nanoscience - Volume 15, Issue 2, 2019

Background: The data on the specific synthesis of elemental silver nanoparticles (Ag-NP) having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various methods, have been systematized and generalized. Objective: It is noted that the forms and sizes of Ag-NP are greatly dependant on the conditions in which they are formed. Method: Comparison of the data of the characteristics of silver nanoparticles obtained by chemical, physicochemical and biological methods has been made. Results: It has been shown that form and size of produced Ag-NP depend strongly on the such factors as temperature, the concentration of silver(I) containing precursor, pH of the solution, the molar ratio between capping agent and silver(I) containing precursor, reducing agents etc., and, also, on the method used for Ag-NP synthesis (chemical, physicochemical or biological). Conclusion: It has also been noted that biological methods of synthesis of Ag-NP are generally more preferable in comparison with the chemical and physicochemical methods. The review covers mainly publications published in the last 20 years.

Synthesis of nanomaterials with desired shape and size is very important for their potential applications. The properties of the nanoparticles synthesis not only vary with size but also changes with shape and morphology which in turn depends on the synthesis methods. There are many synthesis methods but among them reverse micellar method is one of the interesting chemical method and is very useful technique for the synthesis of nanoparticles with desired shape and size. In this method revere micelles are formed by least three components; two of them are non-miscible and the third one is called surfactant which is characterized by amphiphilic properties.

Background: In recent years, nanotechnology is gaining more attention of analytical and biomedical researchers. Nanotechnology derived nanotools deal with the nanoscale length size (i.e., 10-9 m). The particles having size below 100 nm displayed improved properties for attaining increased efficacy, better patient compliance, improved biodistribution and site-specific drug delivery. Method: Google, PubMed, Web of Science portals have been searched for potentially relevant literature to get latest developments and updated information related to different aspects of nanotechnology derived nanocarriers including biomedical applications. Results: Available literature demonstrated that nanotechnology-based nanocarriers like liposomes, dendrimers, polymeric micelles, carbon dots, quantum dots, carbon nanotubes, magnetic nanoparticles, silica nanoparticles, silver nanoparticles and gold nanoparticles have enormous potential applications in the pharmaceutical field. The current review focuses on the drug delivery, bioimaging, tissue engineering and therapeutic applications of different nanotools. Besides these, scope and opportunities, as well as the global market scenario of nanotechnology derived nanotools, have also been discussed. Conclusion: The practice of nanotechnology in the arena of medicine will transform the strategies of detection and treatment of a wide range of diseases in the upcoming years.

Background: This review provides a closer look at recent work in the field of fireworks manufacture, which could see the replacement of micron-sized particles with their nano-scaled counterparts. Moreover, we also discuss micron-sized particles as well as nanoparticles (NPs) from K, Fe, Al, Ti, Ba, etc., that are produced in the atmosphere as a result of these fireworks. One of the possible technological substitutes for fireworks is presented in detail, i.e., the use of ultrasonic spray pyrolysis (USP) technology. Method: We searched Google, Web of Science and PubMed for a literature survey of fireworks and their products: firecrackers, micron-sized and nanoparticles. Moreover, we used some of our own knowledge and experimental data to strengthen the possibility of simulating the synthesis of firework products on the laboratory scale. Results: The use of nano reactants and oxidisers has seen a substantial increase in the sound efficiency and a decrease in the amount of chemicals used, making fireworks more eco-friendly. The application of Al- and Ti-based nano flash powder in the size range from 35 nm to 50 μm resulted in a significant improvement in the ignition properties of the fireworks. Under changing aerodynamic conditions, it is difficult to collect them as samples for real-time monitoring, needed for their characterization or the testing of their harmfulness under laboratory conditions. As a result, NPs below 100 nm in the surroundings could be easily inhaled into the lungs and cause more pulmonary and respiratory problems than micron-sized particles. USP produces nanoparticles in the laboratory that could replace the conventional micron-sized firecracker raw materials, or nanoparticles that are similar to those formed by fireworks. It will also help to identify the physiochemical properties of the airborne particulates in order to understand and evaluate their impact. This review could be valuable for a controlled economic synthesis through USP, and in the use of nanopowders in pyrotechnology that could reduce pollution to a great extent, thus contributing to the growth and good practise of the fireworks industry. With respect to the USP synthesis, we have also discussed in detail the physical (size, shape) and chemical (composition) characteristics of Al2O3 and TiO2 NPs from different precursors and their temperature ranges. An in-depth explanation for a comparative analysis for the formation mechanism of nanoparticles through both fireworks and USP is presented in the final section. Conclusion: We can produce nanoparticles in the laboratory with ultrasonic spray pyrolysis that have similar properties to those produced from fireworks and can then be used for further testing.

Background: The discharge of effluents from the textile and dyeing industries has been a worldwide concern. Although reduced graphene oxide/titanium dioxide (rGO/TiO2) nanocomposite is a potential candidate for wastewater treatment, the influence of graphene oxide (GO) content on its physico-chemical characteristics and its subsequent photocatalytic capabilities in degrading the organic contaminants has not been well established. Objective: The primary objective of this study was to assess the use of rGO/TiO2 nanocomposites with various GO contents for the removal of toxic methylene blue (MB) dye from aqueous solution. Method: In the present study, rGO/TiO2 nanocomposites were fabricated using various GO contents through a one-step solvothermal method. The effect of GO content on the nanocomposite formation was investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The resulting nanocomposites were evaluated against MB degradation under artificial solar light illumination. Results: Based on the photocatalytic results, the highest removal percentage of MB was achieved by 0.15rGO/TiO2, which was about 1.7 times higher than that of 0.01rGO/TiO2. Conclusion: The enhanced removal efficiency of MB by the nanocomposite with the highest GO content (0.15 g) was attributed to the increased active adsorption sites, which greatly promoted the π- π interaction between the aromatic rings of MB dye and the graphitic skeleton of rGO, as well as the electrostatic interaction between the cationic center of MB molecules and the residual oxygen functionalities of rGO.

Background: Microwave absorbing nanocomposite is a kind of material that attenuates the reflection of microwave radiation in the gigahertz frequency range. These materials consist of dielectric and transition nanoparticles tend to exhibit attractive microwave absorption properties due to their high permittivity and permeability loss factors. Method: The FeCo nanoparticles were prepared from the reduction of iron and cobalt ions with hydrazine. Then, the FeCo@TiO2 core-shell nanoparticles synthesized by co-precipitation method and their microwave absorbing performance are investigated. The phase composition, morphology and coercivity properties of the nanoparticles were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The composites of FeCo@TiO2 nanoparticles with the ratio of 30 vol.% and paraffin wax (70 vol.%) in different thicknesses were prepared. The microwave absorption properties of these composites were investigated in the frequency range of 2-18 GHz using the vector network analyzer. Results: These nanocomposites exhibit the excellent microwave absorption characteristics (reflection loss<-20dB) in the bored band frequency range of 6-16 GHz with different absorber thicknesses of 1- 2.2 mm. The maximum absorption capability of -47.76 dB was obtained at the frequency of 7.92 GHz with the thickness of 1.8 mm. Conclusion: Based on this study, it can be argued that the FeCo@TiO2 nanoparticles can be used for the bored band and thin microwave absorbers.

Background: Surface modified magnetite nanoparticles (MNPs), can act as interesting candidates for use in various biomedical areas. Coating MNPs with amino- or carboxylic acidfunctionalized groups can be used as a tool for covalently binding MNPs to biomolecules for medical uses. The conventionally used methods are also mostly multistep routes requiring purification processes. Objective: Herein, we developed a simple and facile approach with potentials for the large-scale synthesis of bare and/or amine- and carboxylic acid-functionalized MNPs. The resulting product and similarly prepared bare MNPs were studied by XRD, FT-IR, DSC-TGA, TEM, FE-SEM, DLS and VSM analyses. Method: The magnetite NPs were deposited on the steel cathode by a cathodic electrochemical deposition procedure. A galvanostatic mode was applied in the electrodeposition experiments at a dc current density for 30 min. The purification steps were done for the prepared samples. The obtained black powders were evaluated by characterization analyses. Results: The XRD peaks are well-matched with a cubic spinel structure of magnetite and confirmed that the amino acid binding process did not result in a phase change in Fe3O4 during the electrodeposition. The presence of amine and carboxylic functional groups on the surface of the electrosynthesized MNPs was confirmed by FTIR. The size increases complicated the presence of the amino acid layer on the iron oxide nanoparticles as compared with bare MNPs. Conclusion: We synthesized amine- and carboxylic acid-functionalized magnetite NPs through facile novel method, and compare with the deposited bare MNPs. Our findings confirmed that the aspartic acid and asparagine can be efficiently coated on the surface of MNPs during their CE electrodeposition. The functionalized MNPs were found to have favorable size and proper magnetic properties which are suitable for biomedical applications.

Background: Ni/rGO composite electrode has been fabricated by facile supergravity electrodeposition as a low-cost catalyst for efficient hydrogen evolution in alkaline media. In this paper, the electrodeposition time is the main research variable. When the electrodeposition time is 100 minutes, the Ni/rGO-100 catalyst manifests the highest electrocatalytic activity toward the hydrogen evolution reaction (HER). In 1.0 M NaOH solution, the overpotential at a current density of 100 mA cm-2, Tafel slope and charge transfer resistance of Ni/rGO-100 catalyst is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. In addition, Ni/rGO-100 catalyst shows a long-term durability at a constant current density of 100 mA cm-2 for 10 h. The outstanding HER electrocatalytic performance of the Ni/rGO-100 is mainly related to the synergetic combination of Ni and rGO, as well as the enlarged exposure of catalytically active sites and improved transport of electrons arising from the good conductivity of graphene. Method: In a classic experiment, GO was prepared by modified Hummers method. The Ni/rGO composite electrodes were prepared by supergravity electrodeposition, which has been reported in detail in our published paper. Firstly, a &#;m 2 cm Ni foam circle was cleaned sequentially in HCl solution (15%), acetone and DI water for 5 min with ultrasonication to be used as a cathode. And a pure nickel pipe was used as anode. The Ni/rGO composite cathodes were electrodeposited in a blackish green plating bath which contained 350 g L-1 Ni(NH2SO3)2·6H2O, 10g L-1 NiCl2·6H2O, 30 g L-1 NH4Cl , 1.0 g L-1 GO colloidal solution with different electrodeposition time, 10min, 30min, 60min, 80min, 100min, respectively. The pH value of the plating bath is 3.5-3.8. The above five electrodes were respectively denominated as Ni/rGO-10, Ni/rGO-30, Ni/rGO-60, Ni/rGO-80, Ni/rGO-100. All composite electrodes were performed under the strength of the supergravity with G=350 g at a current density of 3 A dm-2 at 318 K. Afterwards the Ni foam coated with Ni/rGO hybrid was taken out of the reaction vessel, followed by washing with deionized water to remove physical adsorption residua, and then dried at 80°C. Results: In this paper, the electrodeposition time is the main research variable. When the electrodeposition time is 100 minutes, the Ni/rGO-100 catalyst manifests the highest electrocatalytic activity toward the hydrogen evolution reaction (HER). In 1.0 M NaOH solution, the overpotential at a current density of 100 mA cm-2, Tafel slope and charge transfer resistance of Ni/rGO-100 catalyst is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. Conclusion: In summary, we have synthesized a class of composite electrodes (Ni/rGO) for HER in alkaline solution by electrodeposition under supergravity field. We studied the effect of electrodeposition time on electrode performance in detail. With the increase of electrodeposition time, the number of active sites is enlarged provided by the electrode. When the electrodeposition time is 100 min, we fabricate the best electrode (Ni/rGO-100). The η100, Tafel slope and charge transfer resistance of Ni/rGO-100 is 184 mV, 77 mV dec-1 and 4.173 Ω, respectively. The introduction of graphene and supergravity field plays a key role in improving the performance of the electrodes. This work is a pivotal part of the development of Ni/rGO as a non-precious HER catalyst for green energy field.

Background: Improper storage and raw materials make peanut oil susceptible to Aflatoxin B1 (AFB1). The semiconductor TiO2 photocatalysis technology is an effective technology which is widely used in sewage treatment, environmental protection and so on. Moreover, the photocatalytic efficiency can be improved by doping I. Method: The experiment is divided into two parts. In the first part, supported TiO2 thin film (STF) was prepared on the quartz glass tube (QGT) by the sol-gel and calcination method and the supported iodine doped supported TiO2 thin film (I-STF) was synthesized using potassium iodate solution. In the second part, the photocatalytic degradation of AFB1 was performed in a self-made photocatalytic reactor. The AFB1 was detected by ELISA kit. Results: The photocatalytic degradation of AFB1 has been proven to follow pseudo first-order reaction kinetics well (R2 > 0.95). The maximum degradation rate of 81.96%, which was reached at the optimum iodine concentration of 0.1mol/L, was 11.38% higher than that with undoped STF. Conclusion: The doping of iodine reduces the band-gap of TiO2, thereby increasing the photocatalytic response range. The proportion of Ti4+ in I-STF has decreased, which means that Ti4+ are replaced by I. The I-STF prepared at iodine concentration of 0.1mol/L has good photocatalytic properties.

Background: Nanotubes serve an important role in heavy metal ions for the removal from wastewater. The efficiency of these nanotubes is dependent on the nature of surface, pH, temperature setting and the hydrothermal contact time. Method: The current research sought to find out the efficiency of titanate nanotubes in the removal of Pb2+ and Cd2+ ions from wastewater. The research concentrated on mesoporosity, pH and hydrothermal contact time, as factors affecting the efficiency of titanate nanotubes in the removal of Pb2+ and Cd2+ ions. Titanate nanotubes were prepared at different hydrothermal conditions, the prepared nanotubes were used for efficient removal of Pb2+ and Cd2+. The following technologies were utilized in the research: (1). electron microscopy (FESEM), (2). X-ray diffraction (XRD), (3). highresolution transmission electron microscopy (HRTEM), (4). FTIR and BET surface area were measured by N2 adsorption using Micrometrics TriStar II. Results: The results obtained reveal that increasing the hydrothermal time improved the adsorption efficiency of the prepared material, where the Titanate nanotubes prepared at the longest time (23hr) achieved the highest removal efficiency for both Pb2+ and Cd2+ at pH 2 and pH 3, respectively. The nanotubes prepared at different conditions also showed significant activities, where the removal % exceeded 90 % for all samples at a pH range of 2 to 3. Conclusion: It was conducted that the factors that affected the efficiency could be set at optimum and the removal efficiency attained be increased, to more than 90%.

Background: During past two decades, functional nanomaterials have received great attention for many technological applications such as catalysis, energy, environment, medical and sensor due to their unique properties at nanoscale. However, copper oxide nanoparticles (NPs) such as CuO and Cu2O have most widely investigated for many potential applications due to their wide bandgap, high TC, high optical absorption and non-toxic in nature. The physical and chemical properties of CuO and Cu2O NPs are critically depending on their size, morphology and phase purity. Therefore, lots of efforts have been done to prepare phase CuO and Cu2O NPs with different morphology and size. Method: The synthesis of cupric oxide (CuO) and cuprous oxide (Cu2O) NPs using copper acetate as a precursor by varying the reducing agents such as hydrazine sulphate and hydrazine hydrate via sonochemical method. The phase, morphology and crystalline structure of a prepared CuO and Cu2O NPs were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray (EDS) and UV-Visible Diffuse reflectance spectroscopy (DRS). Results: The phase of NPs was tuned as a function of reducing agents.XRD patterns confirmed the formation of pure phase crystalline CuO and Cu2O NPs. FTIR peak at 621 cm-1 confirmed Cu(I)-O vibrations, while CuO vibrations confirmed by the presence of two peaks at 536 and 586 cm-1. Further investigation was done by Raman, which clearly indicates the presence of peaks at 290, 336, 302 cm-1 and 173, 241 cm-1 for CuO and Cu2O NPs, respectively. The FESEM images revealed rod-like morphology of the CuO NPs while octahedral like shape for Cu2O NPs. The presence of elemental Cu and O in stoichiometric ratios in EDS spectra confirms the formation of both CuO and Cu2O NPs. Conclusion: In summary, CuO and Cu2O NPs were successfully synthesized by a sonochemical method using copper acetate as a precursor at different reducing agents. The bandgap of CuO and Cu2O NPs was 2.38 and 1.82, respectively. Furthermore, the phase purity critically depends on reducing agents.