Journal of Nano Structures
Volume:7 Issue: 4, Autumn 2017

The nanocomposites of polythiophene and carboxylated multiwalled carbon nanotubes (MWCNTs) were synthesized by in-situ chemical oxidative polymerization method using anhydrous ferric chloride (FeCl3) as an oxidant. The MWCNTs functionalized and ultrasonicated to obtain uniform dispersion within the polythiophene matrix. Field emission scanning electron microscopy was used to characterize the morphology of the nanocomposite. X-Ray diffraction, Fourier Transform Infrared Spectroscopy, Raman spectroscopy, and thermogravimetric analysis were used to characterize the synthesized MWCNT-polythiophene nanocomposites. It was found that in-situ polymerized polythiophene layer matrix was formed on carboxylated MWCNT and there was uniform dispersion of MWCNTs within the polythiophene matrix with significant interaction between polythiophene and MWCNTs. The sensitivity response of the prepared MWCNT-polythiophene nanocomposite sensors was studied in using Ammonia gas. The synergistic effects of the polythiophene-coated MWCNTs improve the gas sensing properties. Results showed that the sensitivity increased with ammonia concentration and it is also affected by the MWCNT content in polythiophene matrix. Furthermore, the sensor in pellet form reported here is robust, cost effective, and relatively stable at room temperature.

In this work, the effects of strontium addition on the structure and optical properties of nanostructured bismuth silicate (Bi4Si3O12) thin films prepared via sol-gel were studied. At first, different sols containing the optimum ratio of precursors were synthesized, and then, the prepared sols were coated on the substrate via dip coating. The dip coated samples were dried at 100oC and, in order to obtain the crystalline structure, calcination was done at 700 oC for 1 h. The prepared thin films were characterized and analyzed via scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), atomic force microscope (AFM), and X-ray diffraction (XRD) analyses as well as ultraviolet-visible spectroscopy. The results showed that a homogeneous coating of bismuth silicate with the grain size in the range 35-50 nm could be formed. XRD analysis demonstrated the annealed sample at 700 oC composed of crystalline Bi4Si3O12 phase without any secondary phase. Investigation of the optical properties of the prepared thin films revealed that the addition of strontium decreased transparency from 82 to 78% and band gap from 3.61 to 3.32 eV.

Today a major environmental problem is global warming that is mainly caused due to exhaust and emission of gases. The only way to reduce their ill-effect is by improvement in fuel efficiency of I.C. engines, where most of the power is lost to overcome the friction. In this work, nanoporous anodized layer is formed on an aluminium substrate surface by anodization. Anodization was carried out at different parameters such as voltage, temperature, time to find out optimum conditions to obtain well ordered nanoporous layer. Characreization of anodized porous layer was done by FE-SEM and EDS. After synthesis, anodized layer was treated with anionic surfactant and dipped in lubricant (SAE-15) for tribological applications. Tribology testing was performed on lubricated anodized surface which shows better results in wear and friction as compared to bare substrate. This technique has a lot of potential in improving fuel consumption of I.C. engines, thus may go a long way towards our goal to save environment.

Nickel films with the thicknesses of 30 and 120 nm were deposited on glass substrates, at different substrate temperatures (313 to 600 K) under uhv condition. The nano-structure of the films and mean diameter of grains was obtained for each films using atomic force microscopy (AFM). Their optical properties were measured by spectrophotometry in the spectral range of 190-2500 nm. Kramers-Kronig method was used for the analysis of the reflectivity curves. The Effective Medium Approximation (EMA) analysis was used to determine the values of volume fraction of voids (fv)and establish the relationship between the nanostructure of the film and EMA predictions. Qualitatively good agreements between structure Zone Model (SZM) as a function of substrate temperature and the values of (fv), is achieved. There is good agreement between these values and the results of mean diameter of grains for Ni films too. The absorption peaks of Ni thin films at ~ 1.4 eV and 5 eV are observed, with an additional bump at about 2 eV. The 1.4 eV peak is in particular much stronger than that obtained in earlier works on Ni thin films (Johnson and Christy (1974)) and on bulk Ni sample (Lynch et al (1971) and Ehrenrich et al (1963)). This is resulted from producing thin films under uhv condition. The conductivities σ1 and σ2 calculated from ɛ1 and ɛ2 for Ni films and were plotted vs energy.

Monodisperse copper-iron-sulfide (CuFeS2) nanoparticles as the infrared light absorbing material (chalcopyrite, 0.65 eV), were synthesized based on facile, one step heating up method, by dissolving of CuCl, FeCl3 and SC(NH2)2 as precursors in oleylamine (OLA) alone or in combination with oleic acid (OA) and 1-octadecene (ODE) as solvent. The phase, size, morphology, and size distribution were controlled by the reaction conditions and temperature. The CuFeS2 nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectrum and ultraviolet-visible-near infrared. The three main absorbance region was observed in the ultraviolet, visible and infrared as a hybridization of Fe 3d-S 3p among the valence band (Cu 3d-S 3p) and conduction band (Cu 4s-Fe 4s). Well controlled CuFeS2 triangular pyramidal along with semi-hexagonal and hexagonal shape (~ 20-25 nm) was obtained by using OLA or a mixture of OLA along with OA and ODE, respectively, with 210 °C heating up and 4 h annealing time.

Here, metal nanoparticles were synthesized by chemical reduction of the corresponding metal salts in the presence of chitosan polymer. Binary and ternary metallic-chitosan Pt-Fe-CH, Pt-Co-CH and Pt-Fe-Co-CH nanocomposites were prepared. Transmission electron microscopy images and UV–Vis spectra of the nanocomposites confirmed the presence of the metal nanoparticles. The electrocatalytic activity of the nanocomposites for ethanol oxidation was tested by cyclic voltammetry, Liner Sweep Voltammetry, amperometric i-t curve and electrochemical impedance spectroscopy techniques. The effect of some experimental factors on ethanol oxidation was investigated. CO stripping was used to determine the CO tolerance of the catalysts for ethanol oxidation. Incorporation of small amounts of Co and Fe nanoparticles in the Pt-CH catalyst caused the higher activity of the catalyst for ethanol electrooxidation. The activation energy of Pt-Co-Fe-CH catalyst obtained from the Arrhenius equation was lower than other studied catalysts. These results showed that Pt-Fe-Co-CH catalyst has better catalytic activity for ethanol oxidation among all prepared catalysts.

Highly textured undoped (pure) and Al doped ZnO nanocrystalline thin films prepared by ultrasonic atomization and pyrolysis method are reported in this paper. ZnCl2 water solution was converted into fine mist by ultrasonic atomizer (Gapusol 9001 RBI Meylan, France). The mist was pyrolyzed on the glass substrates in horizontal quartz reactor placed in furnace. The Structural and microstructural properties of the films were characterized by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). FESEM and TEM analysis revealed that the ZnO thin films prepared were porous monodisperse and nanocrystalline in nature, with average particle size of 15 nm. The optical properties of thin films were characterized by UV-Visible and Photoluminescence (PL) spectroscopy. The films were cut in typical size and electrical contactswere made using silver paste and copper wires. The thin film based sensors so prepared were tested on exposing the simulants of chemical warfare agent (CWA) like: DMMP, CEES and CEPS. Sensors showed better response to DMMP (a simulant of sarin gas) as compared with its responses to CEES and CEPS. Al (1 at%) doped ZnO thin film based sensor showed highest response to DMMP (2 ppm). The simulant response, selectivity and response-recovery time of the sensors were measured and presented. The role of Al dopant in ZnO to enhance DMMP response is discussed.

In this work, PbSe and PbTe sensitized TiO2 solar cells were fabricated. PbSe and PbTe nanostructure was deposited on the TiO2 surface via a drop cast method. The fabricated surfaces were examined by atomic force microscopy (AFM). Also the optical properties of the layers were studied by diffuse reflectance spectroscopy (DRS) spectra. The morphology of the surfaces was obtained by scanning electron microscopy (SEM) images. The structure and phase of the obtained materials were studied by X-ray diffraction pattern (XRD). Furthuremore chemical elements of the fabricated layers were examined by energy dispersive X-ray analysis (EDX) spectra. The solar cells were made by the fabricated layers, Pt as a counter electrode, I3-/I- electrolyte, surlyn as a sealer and silver paste to enhance collection of the produced current.

Nanofiltration is increasingly gaining attention in many separation and treatment processes such as water softening, color removal and separation of medicines. Nanofiltration membranes are often negatively charged, displaying separation characteristics in the intermediate range between reverse osmosis and ultrafiltration. In this research, a novel nanofiltration membrane prepared with poly(amidoamine) (PAMAM) dendrimer and graphene oxide (GO) on amidoximated acrylic ultrafiltration membrane was investigated. Scanning Electron Microscopy (SEM) and contact angle of the water were employed to characterize the chemical and physical changes of resulting membranes. The flux and rejection of resulting membranes increased with increasing generation numbers of PAMAM for NaCl concentration. The salts rejections order of resulting membrane is CaCl2>MgSO4>NaCl>Na2SO4, which shows that resulting membranes were all positively charged NF membrane. The PAMAM/GO NF membrane is especially suitable for separating cationic solutes from others. This kind of membrane is also particularly suitable for treating acidic feed. The studied membrane possesses maximum operating pressure lower than 4 bar and excellent stability during continuous filtration at 27±2°C.

This study reports a green approach to synthesis of monometallic platinum nanoparticles (Pt NPs) and bimetallic aurium@platinum nanoparticles (Au@Pt) using aqueous leaf extract of Carica papaya as a reducing and stabilizing agent. The nature and morphology of as-synthesized PtNPs and bimetallic Au@Pt NPs were characterized using UV/vis spectroscopy (UV–vis), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray (EDX). HRTEM images reveal that the as-synthesized PtNPs are in the size range of 3.94–5.48 nm with average particle size of 4.50±0.80. The HRTEM image of as-synthesized Au@Pt shows distinguishable objects of almost same spherical shape but having different contrast with size ranging from 4.17 to 13.23 nm and average particle size of 8.70±2.50 nm. The EDX data of Au@Pt nanoparticles reflects bimetallic nature, and the individual metal of the bimetallic Au@Pt nanoparicles are present almost in the ratio 2:1. The narrow size distribution and small average size (