Journal of Nano Structures
Volume:4 Issue: 1, Winter 2014

To explore the possibility of using graphene based biosensor, adsorption of hydrogen peroxide on graphene has been investigated using density functional theory. The electronic properties of defect free and defective graphene in the presence of different number of hydrogen peroxide have been studied. The graphene with the most stable configuration defect named as SW defect is considered. The high adsorption energies indicate chemisorption of hydrogen peroxide on graphene. It is found that defect free graphene exhibits semimetallic behavior, while graphene with Stone-Wales defect shows semiconducting property. The charge is transferred from hydrogen peroxide to graphene. At low concentration of this donor molecule, defect free and defective graphene become n-type semiconductors. The energy band gap is decreased and metallic behavior is observed in graphene by increasing the number of hydrogen peroxide. The sensitivity of the electronic property of graphene to the presence of hydrogen peroxide suggests that these nanostructures are good choice to design biosensor for hydrogen peroxide detection.

Some issues; leakage, tunneling currents, boron diffusion are threatening SiO2 to be used as a good gate dielectric for the future of the CMOS (complementary metal- oxide- semiconductor) transistors. For finding an alternative and novel gate dielectric, the NiO (Nickel oxide) and PVA (polyvinyl alcohol) nano powders were synthesized with the sol-gel method and their nano structural properties were studied using the X-ray diffraction (XRD), Atomic force microscopy (AFM), Scanning electron microscopy (SEM), UV-Vis spectrophotometer and GPS 132 techniques. The obtained results indicated that the sample (5 g NiO and 0.02g PVA prepared at 30˚C, annealed in an oven at a temperature of 80˚C) can fill this gap due to its higher dielectric constant, better morphology, less rough surface and less leakage current.

In this study, ZnO nanoparticles were loaded on activated carbon prepared from almond shell (ZnO-NP-AC). Then, this novel material applied as an efficient adsorbent for the ultrasonic assisted simultaneous removal of Basic Blue 41(BB41) and Basic Red 46 (BR46) in binary solution. The efficiency of proposed activated carbon was enhanced by acid treatment and subsequent modification by physical mixing with ZnO- NP. The identification by different techniques such as FT-IR, SEM and XRD confirm its porous structure and appearance of various functional groups on AC. In batch process mode, the effect of variables such as adsorbent dosage, initial dyes concentration and sonication time on the removal of dyes were studied by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). The optimum values of input variables were found to be 0.03 g of adsorbent, 19 min of sonication time, 14 mg/L of BR46, 9 mg/L of BB41in pH 6 to high removal percentage (85% and 91% for BR 46, BB41, respectively). Among of the conventional isotherm and Kinetic models, p-factor and second-order models showed reasonable fit to the adsorption equilibrium data, respectively.

The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH) conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and Nb sources, respectively. Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3. In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology. Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

New kinds of hydroquinone derivatives were synthesized and along with a azo dye applied as additives in the iodide/iodine redox electrolyte for dye-sensitized solar cells and their effect on the short-circuit photocurrent of dye sensitized solar cells was investigated. Addition of 0.05 M a hydroquinone derivative in the electrolyte comprising 0.5 M 1-methyl-3-propylimidazolium iodide (MPII) and 0.05 M I2 in a mixture of acetonitrile and valeronitrile (volume ratio, 85:15) enhanced significantly photocurrent density from 11.1 to 12.8 mA/cm2, and voltage increased from 0.66 to 0.68 V. As a result, overall conversion efficiency increased from 4.4% to 4.8%, corresponding to increment of 10.9%.

Transparent glasses in a system of Li2O-MgO-SiO2-Al2O3-Fchemical constituents were prepared by melt quenching method. In the fabrication of nanocrystal glass-ceramics, controlled nucleation and subsequent crystal growth were necessary to avoid loss of transparency. It was therefore important to understand thermal properties and crystallization kinetics of the glass ceramics. The crystallization behavior of the prepared glass was investigated by DTA, XRD and SEM. By crystallization heat-treatment, various crystalline phases, microstructure and transmittance were obtained. The sellaite was first precipitated as the nuclei before the crystallization of mica and then mica nanocrystals were precipitated with average size of <40 nm. In this respect, the nucleation process was optimized in order to achieve a fine mica microstructure.

N-sodium acrylate-O-carboxymethyl chitosan [CMCH-g-PAA(Na)] bound Fe3O4 nanoparticles were developed as a novel magnetic nanoparticles with an ionic structure that can be potentially used in many fields. CMCH-g-PAA (Na) was obtained by grafting of sodium polyacrylate on O-carboxymethyl chitosan, which is an amphiphilic polyelectrolyte with the biocompatibility and biodegradability properties. According to the great interest for improving the stability of Fe3O4 nanoparticles, CMCH-g-PAA (Na) was used as a stabilizer to prepare a well dispersed suspension of magnetic nanoparticle According to the results,the presence of CMCH-g-PAA(Na) could eliminate agglomeration of magnetic nanoparticles without destroying the superparamagnetic properties

High solid content poly (styrene-co-butyl acrylate) latex (with 20% and 40% solid content) including high amounts of Cloisite 30B (7 wt% and 10 wt%) were kinetically investigated. Gravimetric method via measuring the rate of polymerization, number of particles and average number of radicals per particle was used. Results showed that by increasing the solid content; the average diameter of polymer particles decreased. Studies on the polymerization rate depict that the increase in polymer particle size provides more average reactive radicals per polymer particle, which increased from 0.48 to 0.88 for the sample containing 7 wt% clay and 20 wt% solid content. Observed armored particles with honeycomb morphology is the most novelty of this research work, which is suitable for making barrier packaging films.

In this investigation, Ag@TiO2 nanocomposite was prepared by deposition of silver nanoclusters onto commercial TiO2 nanoparticles (known as P25 TiO2) via photodeposition technique as clean and simple photochemical route. The synthesized Ag@TiO2 nanocomposite was utilized in the fabrication of dye-sensitized solar cell (DSSC) chiefly because, compared to pure TiO2, the electron affinity of Ag@TiO2 nanocomposites is higher which enhances the photo-generated excitons lifetime, and as result, reduces the rate of photo-generated charge carriers recombination. Additionally, we found that via deposition of silver nanoclusters, TiO2 absorption in visible light region was considerably improved due to the surface Plasmon phenomenon. XRD results proved existence of anatase and rutile phases within TiO2 structure. Finally, photovoltaic performance and solar energy conversion efficiency of TiO2 and Ag@TiO2 electrode-based DSSC were compared and discussed.

We report the growth and characterization of Cu nanoparticles thin film of on glass substrate by pulse laser deposition method. The Cu thin film prepared with different energy 50, 60, 70, and 80 mJ. The energy effect on the morphological, structural and optical properties were studied by AFM, XRD and UV-Visible spectrophotometer. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 65.8 to 90.09 nm. The results showed the Average Gran Size increased with increasing energy and RMS roughness increased with increasing energy. X-ray diffraction showed nanostructure phase With (2q = 43.297, 50.433 degree). The results show that by increasing thickness, the copper films crystallinity in (111) direction increases. Optical properties measurements showed transformation from metallic properties of bulk Cu to semiconductor properties when formed by sort of nanostructure evidenced by the formation of optical energy gap about (3.45 to 3.89 eV) with different conditions. When the thickness of samples is increased the crystallinity and the mean grain size improved.

3,3,6,6-Tetramethyl-9-phenyl-3,4,6,7,9,10-hexahydroacridine-1,8-(2H,5H)-dione derivatives are synthesized by nano titanium dioxide as an efficient and reusable heterogeneous nano catalyst in a one pot multi component reaction. Easy preparation and separation of catalyst, simply workup procedure, clean reaction and reusability of the catalyst up to 7 times without appreciable loss of its catalytic activity and high yields are some advantages of this work.

Paraloid-Mg(OH)2 nanocomposites were synthesized via sonochemical method. Nanostructures were characterized by XRD and SEM. Thermal stability behavior of paraloid filled with magnesium hydroxide was investigated by thermogravimetric analysis (TGA). The influence of Mg(OH)2 nanostructures on the flame retardancy of the paraloid matrix was studied using UL-94 analysis. Our results show that the Mg(OH)2 nanostructure can enhance the flame retardant property of the paraloid matrix. The enhancement of flame retardancy of nanocomposite is due to endothermic decomposition of Mg(OH)2 that absorbs energy and simultaneously releases of water (dilutes combustible gases). Photo-catalytic activity of the nanoparticles was evaluated by monitoring the degradation of methyl orange (MeO) in an aqueous solution.

Nanocrystalline titanium (iv) oxide paste has been deposited on Fluorine doped tin oxide glass substrate by the blade method. The deposited film was subjected to thermal treatment to obtain an electrode foe a photo-electrochemical cell. The electrode was sensitized with prophyrin dye which was a local dye extracted from carica papaya leaves. Avaspec 2.1 spectrophotometer was used to obtain the absorbance data, while the Tauc Model was employed to estimate the optical band gap of the sensitized film. The sensitization process led to band gap narrowing and, hence, the prophyrin-dyed electrode could absorb light beyond the ultraviolet region. Also, the current-voltage characteristics of a dye sensitized solar cell based on the prophyrin dye revealed that the natural dye is a good photosensitizer.