Nanochemistry Research
Volume:2 Issue: 2, Summer and Autumn 2017

Cu and Ni ferrites as the semiconductor materials were synthesized by a microwave sol-gel auto-combustion method. Two cationic surfactants, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), were applied and the influence of surfactants on the properties of the Cu and Ni ferrite particles was studied. The samples were characterized by X-ray powder diffraction (XRD) pattern, scanning electron microscope analysis (SEM), Fourier transform infrared (FT-IR) spectroscopy and diffuse reflectance spectra (DRS). Powder XRD analysis and FT-IR spectroscopy confirmed the formation of ferrite spinel phase. The crystallite size was calculated to be 50-95 nm using Scherrer’s equation. The morphology and size of the synthesized nanoparticles have been observed by scanning electron microscopy. The particles were agglomerated without using surfactant. Using CTAB leads to the samples with layer shapes, and  using SDS leads to  the samples  with pyramidal shapes. The energy band gaps  calculated from UV–DRS absorption by using Kubelka-Munk equation were 1.68-1.77 eV, indicating that band gap of Cu ferrites becomes small and band gap of Ni ferrites becomes large in the presence of surfactant.

Iron oxide (Fe2O3) nanoparticles were prepared by combination of sol-gel autocombustion and ultrasonic irradiation. The XRD pattern reveals that the crystallite size of sample is 36.7 nm and the phase identification shows hematite, syn has been crystalized. The morphology of the sample investigated by FESEM showed that particle size of the sample was about 76 nm. The optical property of Fe2O3 investigated by DRS showed that there may exist three energy band gaps in iron oxide nanoparticles . FT-IR technique was used to determine the functional group of product. In agreement to XRD results, the result of FT-IR revealed no organic residue in product. Photo catalyst nanoparticles were immobilized on the surface of glass slide using Doctor Blade method. Photocatalytic degradation of reactive red 4 (RR4) was investigated under UV light using iron oxide nanoparticles as catalyst. The kinetic of RR4 degradation under UV light irradiation in the presence of Fe2O3 as photocatalyst, and rate constant was determined. Experiments exhibited that Fe2O3 nanoparticles decomposed 52% of azo dye RR4 in solution duration 135 min. The photo catalytic reaction kinetic of RR4 degradation in the presence of Fe2O3 nanoparticles followed Langmuir-Hinshelwood model with the rate constant of about 0.005 min-1.

In this study, colloidal germanium nanocrystals were synthesized by a simple and novel method, and their optical properties were also studied. Polyvinyl alcohol (PVA) as a surface modifier was used to control the optical properties of colloidal Ge nanocrystals. Fourier transform infrared spectroscopy (FTIR) analysis was performed to identify the various functional groups present in the sample. TEM was used to confirm the formation of nanocrystals and observe the morphology and size of particles. To investigate the optical properties of the prepared nanocrystals, UV-Vis absorption and emission spectroscopy were also employed. Experimental results showed that the synthesized Ge nanocrystals have a spherical shape with the average particle size about 7 nm. FTIR spectrum indicates that Ge nanocrystals are well passivated with minimal surface oxidation. They exhibited luminous blue appearances of light. The emission peak is located at 455 nm wavelength. Also, the direct optical band gap of Ge colloidal nanocrystals was evaluated by Tauc's theory. The crystallinity of Ge nanocrystals was also evaluated by X-ray diffraction pattern analysis. The X-ray diffraction peaks confirmed that Ge nanocrystals have been crystallized in the diamond cubic crystallization

In this study, a new recoverable catalyst for the epoxidation of olefins was developed using a layered polysiloxane as a support for immobilizing  (salen) molybdenum(VI) complex by electrostatic interaction between the surface of the solid support and the electrically charged molybdenum complex. Characterization of the heterogeneous catalyst by Fourier transform infrared, XRD,1H NMR, and atomic absorption spectroscopes as well as thermogravimetric and CHN elemental analyses confirmed successful immobilization of the (salen) molybdenum(VI) complex to the support. The prepared catalyst catalyzed the epoxidation of olefins efficiently. The effect of different factors on the epoxidation of cyclooctene was investigated. Reaction conditions including reaction temperature, solvent type, substrate amount, catalyst amount and oxidant  amount  were systematically optimized in order to achieve the highest conversion of cyclooctene. Various other olefins showed high catalytic activity and selectivity under the optimal reaction conditions. Regenerability test demonstrated that the catalyst can be recycled for at least five times without leaching of molybdenum. Moreover, the catalyst showed good stability under the reaction conditions as determined by FT-IR and ICP-OES analyses.

Magnetic-fluorescent lanthanide doped sodium lutetium fluoride (NaLuF4:Yb3+/Er3+/Gd3+) nanocrystals were synthesized via facile hydrothermal method by varying concentration of Gd3+. Powder X-ray powder diffraction (PXRD), scanning electron microscopy (SEM),transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), particle size by dynamic light scattering (DLS),photoluminescence (PL) and magnetic studies were used to characterize the structural, optical and magnetic properties of these nanocrystals. Powder X-ray diffraction  results  signified  good  crystallinity  and  effective  doping  in  sodium lutetium fluoride nanocrystals. The SEM and TEM micrographs defined their flower like morphology. The EDS was performed to investigate the presence of dopant. The emission intensities of the prepared samples are strongly controlled by particle sizes which are influenced by co-doping NaLuF4 nanocrystals with varying concentration of Gd3+. Besides the efficient optical properties, Gd3+ doped NaLuF4 nanocrystals exhibited paramagnetic behavior at room temperature with magnetization of up to 8.24× 10-3 emu g-1 at 15 kOe.

Indium (1at %) doped ZnO and ZnO nanoparticles have been synthesized via sol gel method. The structural characters of the synthesized nanoparticles have been studied by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM) and energy-dispersiveX-ray spectroscopy (EDX). From synthesized nanopowders a tablet was prepared by using the isostatic pressing and then sintered at 600°C. Then, the gas-sensing properties of ZnO and IZO powder tablets were evaluated with respect to the acetone gas at different temperatures and concentrations. XRD pattern and SEM images showed the prepared samples were crystallized in the wurtzite structure with the average particle size of 32 and 27 nm. The gas sensing measurement results showed that the indium dopant ions improved the gas sensitivity of ZnO for high acetone concentrations effectively. Therefore, it is suggested that the IZO tablet can act as reliable and low cast gas sensor for acetone detection. Sintering temperature strongly increased the grain size and density of samples. EDX analysis confirmed the presence of indium in zinc oxide structure.

Ethylene glycol bisthioglycolate modified gold nanoparticles grafted Mn doped Fe3O4 nanoparticles (Au@Mn-Fe3O4 NPs) adsorbent was synthesized and applied for extraction and preconcentration of trace amounts of Ag+ and Pb2+ ions in artificial and natural saliva. The adsorbent was characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), X-ray diffraction spectroscopy (XRD) and vibrating-sample magnetometer  (VSM) [h1] techniques and Fusayama artificial saliva was prepared and used as a blank sample. Natural saliva samples were collected from nine volunteers who exposed to posterior decayed teeth amalgam filling, and short-term release of heavy metal ions was assessed in 24, 72 and 96 h after filling. The main factors affecting extraction and desorption efficiency of target ions have been investigated. In Optimum conditions, the detection limits of 0.23 and 0.11 ng mL-1 with preconcentration factors of 94 and 95 were obtained for Ag+ and Pb2+ ions, respectively. The results revealed that the adsorbent has high  capacity and good reusability for extraction and preconcentration of target metal ions in relatively high saline solution like biological fluids.

Enzymatic biofuel cells have many great usages as a small power source for medical and environmental applications. In this paper, we employed carboxylated multiwall carbon nanotube- (1-ethyl-3-methylimidazolium bis (trifluoromethyl sulfonyl) imide) ionic liquid nanocomposite on two different electrodes (glassy carbon and carbon felt) for immobilizing alcohol dehydrogenase. The properties of the two types of electrodes were characterized by cyclic voltammetry analysis. Polarization analysis and field emission scanning electron microscopy were used to show differences in the nanobiocomposite immobilization on two electrodes. Compared to glassy carbon, carbon felt achieved much more gains in electrochemical activity and power by catalyst coating. Power density of 10.027μWcm−2, has been achieved by carbon felt, but glassy carbon showed 1.7 μWcm−2 respectively.

An efficient and reusable adsorbent, namely 3-mercaptopropionic acid modified tetraethyl orthosilicate (TEOS) grafted MnFe2O4 nanoparticles (MPA-TEOS-MnFe2O4 NPs) was synthesized and used for the extraction and preconcentration of trace amount of Al (III) and Cr (III) ions in water samples. MnFe2O4 NPs were prepared by chemical co-precipitation of manganese (II) and iron (III) salts in alkaline medium and then, modified by TEOS to create an inert layer preventing nanoparticle agglomeration. The TEOS-MnFe2O4 NPs were then modified with MPA to produce an adsorbent with carboxylic acid functional groups which have tendency to hard metal ions such as Al(III) and Cr (III). The prepared adsorbent was characterized by SEM, XRD, VSM and FT-IR techniques. The Al (III) and Cr(III) ions were measured by graphite furnace and flame atomic absorption spectrometric techniques, respectively. Various factors affecting extraction/desorption efficiency of target ions were investigated and analytical characteristics of the method were determined and detection limits of 0.5 and 0.2 ng mL-1 with preconcentration factor of 69 and 72 were obtained for Al (III) and Cr(III) ions, respectively. The results revealed that the adsorbent has high capacity and good reusability for extraction/preconcentration of target metal ions in tap and drinking water samples.

During thelast20-30 years, palladium-catalyzed reactions have witnessed tremendous advances in the industrial and organic reactions such as hydrogenation, coupling, cyanation and amination. Despite the wide utility of Pd-catalysts in these reactions, they suffer from a number of drawbacks such as recovery, reuse of catalyst and remain as  a contaminant in the products at the end of the reaction. A powerful and convenient reaction procedure for the C-N coupling reaction (the Buchwld-Hartwig reaction), yielding products of N-arylanilines and N-arylamines in conventional heating has been reported. The protocol utilized an high stable Pd(EDTA)2- salt by counter cation of N-methylimidazolium bounded to 1,3,5-triazine-tethered SPIONs (superparamagnetic iron oxide nanoparticles). The reaction products were produced under conventional heating at extremely low catalyst loading (as low as 0.003 mol% Pd).Finally, we also examined the reusability of the catalyst.  It was found that the catalyst could be recovered by external magnetic field and be reused for five times without obvious loss in catalytic activity.

The palladium metal is the most frequently used metal because of its excellent catalytic efficiency and most flexible varying oxidation state. So,  we report  that palladium nanoparticles (Pd NPs) stabilized by a ligand (o-vanilindiphenylethanedionedihydrazone, L)  using reverse micelles method have been synthesized, while all particles are in spherical shape and ranging between 10 and 15 nm. This has been characterized by 1H NMR, IR, UV, X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscope (SEM) analyses. These nanoparticles were used as a catalyst for coupling reaction between aryl halides with terminal alkenes, Heck reaction, in the presence of potassium carbonate (K2CO3) as a base and NMP (N-Methyl-2-pyrrolidone) as a solvent.  The present catalyst is an air and moisture stable and has significant catalytic activity in Heck cross-coupling reactions under operating conditions. Various aryl halides and terminal alkenes were coupled smoothly under air to afford the corresponding cross-coupled products in excellent yields.

Two dimensional silver(I) coordination polymer, [Ag(μ5-T4S)]n (1), (T4S- = toluene-4-sulfonate), has been synthesized and characterized by Inductively Coupled Plasma (ICP) and elemental analyses, IR spectroscopy and powder X-ray diffraction. This compound was calcined at 450, 500 and 700 °C in a furnace and static atmosphere of air. The resulting compound from 1 at 450 °C is a spongy nanostructure which could not be characterized due to its partial calcination process. At 500 and 700 °C, the compound is a mixture of silver and silver sulfate compacted nanosheets and microstructures. By increasing the temperature  from 500 to 700 °C, the tendency for the formation of agglomerated mixture of silver and silver sulfate was increased. In addition, a number of one-step techniques including electrochemical deposition method, electroless deposition method, direct deposition method, redox reaction, mirror reaction, coating technique, self-seeding or self-assembling process and wet chemical method have been reviewed for the synthesis of two-dimensional nano silver.