Abstract: Iron nanoparticles (FeNPs) were prepared from the green tea extracts at different temperatures through green synthesis procedure and characterized by various physicochemical techniques like UV-Visible spectroscopy, FTIR Spectroscopy, energy dispersive X-ray spectrometry (EDS), X-ray diffraction and high resolution tunneling microscopy (HRTEM) and the results confirmed the synthesis of polydisperse and stable FeNPs by the tea extracts. The catalytic activity of FeNPs was investigated using a common environmental pollutant BTB often used in textile industries for dyeing purposes. In these tests, catalytic degradation of BTB with FeNPs at a 10 μL or 30 μL concentration was done in the presence of 2% hydrogen peroxide. Results show no BTB degradation in the absence of the FeNPs. However, a 38% and 68% degradation of BTB was realized in the presence of 10μL and 30 μL FeNPs respectively indicating that the iron nanocatalysts were responsible for the dye degradation. The BTB degradation kinetics was found to follow pseudo-first order kinetics with rate constants at the two catalyst concentrations being 0.023 min-1 and 0.063 min-1 respectively.
Abstract: Nanoscale experiments with diamond tip that include processing, visualization and tunneling spectroscopy of the surface are presented. Single crystal diamond synthesized by the temperature gradient method under high pressure–high temperature (HPHT) conditions is proposed as a multifunctional tip for scanning tunneling microscopy (STM). Sequence of the procedures covering growing crystals with predetermined physical properties, selection of the synthesized crystals with the desired habit and their precise shaping have been developed. The original STM’s peculiarity is the electromagnetic probe-to-surface load measuring system. The results of fabrication and characterization of nanostructures for nanoelectronics, data storages and biology are demonstrated and discussed.
Abstract: The fabrication of gold-loaded magnetite/silica core-shell particles was presented in this paper. First, 250 nm of magnetic Fe3O4 nanoparticles were prepared by solvothermal reaction. Then, the Fe3O4 particles were coated by SiO2, and Au nanoparticles (AuNPs), respectively. The core-shell structure of these microspheres was confirmed by transmission electron microscopy (TEM) and Power X-ray diffraction (XRD). The magnetic property of the core-shell microspheres was investigated at room temperature. The results indicated that the core-shell composites had a well-retained high magnetic intensity, thus it can be easily separated from the mixture in less than a few minutes by simply using a magnet.
Abstract: Zinc oxide nanoparticles have been synthesized by a sol-gel microwave assisted method using either ethylene glycol (ZnO-EG) or poly ethylene glycol ethanolic solution (ZnO-PEG) as dispersing media. The nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared. X-ray analysis revealed a hexagonal phase structure of both zinc oxides. The average crystallite size calculated from Scherrer equation was 27 nm and 53 nm in good agreement with 24 nm and 55 nm microscopic results for ZnO-EG and ZnO-PEG, respectively. The catalytic activity of the as-prepared nanoparticles was compared by the photodegradation of 2-nitrophenol under UVC. The effect of various parameters such as pH, catalyst weight, and pollutant concentration on the percent degradation was investigated. Best optimization was pH=7, 0.06g of nanoparticles weight, and 10 mg.L-1 pollutant concentration. Furthermore, pseudo first order kinetic based on Langmuir–Hinshelwood (L–H) model was proposed for degradation reactions and experimental data were in good agreement with this model.
Abstract: Phosphorus-doped p-type ZnS NWs were synthesized by chemical deposition method. The as-synthesized NWs shows obvious p-type conduction with a hole concentration of 8.35 × 1017 cm-3. ZnS-Si core-shell nanoheterojunction was fabricated by depositing Si thin film on the surface of ZnS NWs through a sputtering method. The core-shell nanostructure exhibited excellent photoresponse to white light and UV light. Under UV light illumination, a high performance with a responsibility of ~ 0.14 × 103 AW-1, a gain of ~ 0.69 × 103 and a detectivity of ~ 1.2 × 1010 cmHz1/2W-1 were obtained based on the ZnS-Si core-shell nanoheterojunction. This new nanostructure is expected to play an important role in the next-generation optoelectronic devices.
Abstract: Visible light responsive CoTiO3 nanoparticles with average diameter of 100 nm were successfully synthesized by sol-gel method and were firstly applied to catalytic activation of peroxymonosulfate (PMS) for degradation of organic pollutants (Rhodamine B (RhB)). Photocatalytic experiments illustrated that CoTiO3 nanoparticles reveal good photocatalytic activity and excellent ability to activate PMS, the synergistic effect of visible light photocatalysis and sulfate radical generated from activated PMS can degradate RhB efficiently. Besides, CoTiO3 nanoparticles maintain their high photocatalytic and activation efficiency after three times recycling.
Abstract: PLGA, poly (lactic-co-glycolic-acid), is a kind of biodegradable functional macromolecular organic compounds. PLGA, certified by the Food and Drug Administration (FDA), possesses desirable features of biocompatibility, nontoxicity and no immune response, and is being widely applied to human clinical medical research. Because of its biodegradability, simple synthetic methods, controllability of degrading rate and desirable plasticity, PLGA was applied in large quantity into the carrier materials which is to control the release in recent years, gradually propelling PLGA microsphere controlled release system to be the most ideal drug-carrier system at present. As the carrier of drug and genes, PLGA is mainly researched on its features as the carrier, synthetic methods, different surface modification methods, and the applications on different drugs, genetic treatments and genetic vaccines.
Abstract: Hybrid nanostructured Metal Oxide Semiconductor (MOS) capacitor was fabricated on silicon substrates (n-type) using chemical solution deposition with YMnO3 as an oxide layer. Electrical properties of MOS capacitor have been investigated with frequency dependence capacitance-voltage (C-V) characterization. The surface morphology of deposited layer was studied using the Atomic Force Microscopy (AFM). Hysteresis in the C-V loop and change in the values of Cminimum were described by a charge trap mechanism in the multiferroic oxide layer of MOS devices. While anomalous behavior in saturation capacitance in the inversion as well as in accumulation region and a shift in threshold voltage (VT) were explained in the vicinity of frequency depended Debye length (LDebye).
Abstract: Density functional theory was used to investigate the effect of size on the adsorption state of hydrogen atom on small cobalt particles. For this propose, we have performed series of DFT-GGA calculations on various sizes of Co clusters, between 4 and 24 atoms, and a Co FCC (100) slab, with and without hydrogen atom adsorbate. The results showed that the destabilization and the cohesive energies per atom in a metal cluster are represented as linear function of the surface-to-volume ratio of the metal clusters. In addition, the energy of the HOMO–LUMO gap from 4s and 3d valence orbitals of the cobalt atoms in the cluster is decreased with increasing in cobalt cluster size, which is size dependent parameter. We have studied the effect of the size of Co clusters and the infinite Co (100) surface, on the energy of adsorption of hydrogen atom. The calculated Eads for hydrogen atom in our considered cobalt clusters showed decreasing behavior with increasing of the number of atoms in cluster.
Abstract: Catalysis is one of the hottest research topics in chemistry. In recent years, metal complexes attracted great interest as catalysts towards various types of organic reactions. However, these catalysts, in most cases, suffer from the deficits during their recovery, recycling and the difficulty in separation of catalysts from the products. Therefore, the design and synthesis of recoverable and recyclable catalyst is very important aspect in catalysis. The aim of this review article is to highlight the speedy growth in the synthesis and catalytic applications of magnetic nanoparticles (Fe3O4, MNPs) supported N-heterocyclic carbene (NHC) and amine based metal complexes in various organic reactions. Furthermore, these catalysts can be easily separated from the reaction media with the external magnet and reused various times without a substantial loss of catalytic activity.