NANOSCALE
Year:2017 | Volume:3 | Issue:4|Papers Count:7

Photocatalytic wastewater treatment as an important member of advanced oxidation processes with a high energy efficiency plays important role in wastewater treatment. This method is known as an energy efficient method because of solar light utilization availability. In this work, TiO2 nanophotocatalyst has been synthesized using titanium (IV) butoxide as a Ti precursor. Then, the nitrogen doping was considered to activate the photocatalytic ability in the visible part of the light spectrum. N-TiO2 nanophotocatalysts were synthesized using a hybrid method of hydrothermalmicrowave. The analyses of XRD, FESEM, BET, EDX and UV-vis spectroscopy were carried out to evaluate the physicochemical and optical properties of the catalysts. The XRD analysis has confirmed the successful synthesis of the TiO2 with anatase crystalline phase. FESEM images have confirmed the nano-sized structure of the catalysts. The BET surface area coincided the FESEM results by representation of surface area enhancement after doping with nitrogen. EDX has verified the presence of nitrogen in the sample and demonstrated uniform dispersion and no agglomeration of Nitrogen presented on the catalyst surface. The photocatalytic degradation of dye from the synthetic wastewater was carried out resulting the highest photocatalytic activity for N-TiO2 in comparison to undoped samples. The experiment resulted 90 percent of degradation after 140 min while undoped TiO2 represented just 52 percent of degradation. Also, to have a better comparison, the industrial photocatalyst P25 was used in the same experiment time and operational conditions. The results depicted higher photocatalytic activity for hydrothermal-microwave synthesis of TiO2 compared to industrial TiO2 with 15 percent higher degradation. N-TiO2 Nanophotocatalyst, Microwave-Assisted Hydrothermal, Acid Orange 7, Water Treatment.

In this article we will show how different molecules can be identified by the use of graphene nanoribbon. Conductance depend on frontier energy level and spatial orientation of molecules. With this feature, electron transport through molecules that are physically attracted to nanoribbon can be described and calculated. We show that electron transport is unique to each molecule. Because when a molecule attach on graphene nanoribbon sharp dips in T-E graph appears that these dips are different for each molecule. In this paper, physical adsorption of three molecules like ethanol (C2H6O), sulfur dioxide (SO2) and benzene (C6H6) has been studied on graphene nanoribbon.

Nanoparticles as a common material have been used in nanotechnology and their interesting properties lead to variety of applications in the technological areas such as chemical industry, medical science, electronics and agriculture. Carbon nanotubes and gold nanoparticles have been focused among the different nanoparticles due to their unique physical and chemical features such as high surface to volume ratio which cause them to have various analytical applications in Biosensors. In this paper, carbon nanoparticles are grown between two metallic electrodes by using pulsed arc discharge method then are used to electro-chemical detection of vegetal DNA.

Strontium hexaferrite nanocrystallites were prepared by the sol–gel autocombustion method followed by calcination at 900oC for 1h under different molar ratios of reductant/oxidant. The structural properties of strontium hexaferrite nanoparticles were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the particle size of the resultant powder was about 50-80 nm. The photocatalytic activity of magnetic strontium hexaferrite under UV light was evaluated using Methylene blue (MB) as a model compound for organic contaminants. The maximum degradation efficiency (46%) was achieved at molar ratio of reductant/oxidizer 0.8. Reasonably high values of magnetization, the strontium hexaferrite nanoparticles could be easily separated from the environment by using a low strength magnetic field after the reaction.

In this paper, we study the electronic conductance of the flat and bent armchair and zigzag graphene nanoribbons in the presence and absence of an external magnetic field within the nearest neighbor tight-binding approach. For the armchair case, we reduce the Hamiltonian of each benzene ring including the treated magnetic flux to the Hamiltonian of a two atomic molecule by using the renormalization method. Also, consider the effect of magnetic field by inserting the flux dependent phase coefficients in the corresponding hopping energies in the problem. Finally, we perform the numerical calculations related to the transmission coefficient by the means of the Green’s function technique within the Landauer approach. The results show that the applying an external magnetic field on the armchair nanoribbon creates some extra gaps in the conductance spectra. The widths of these gaps depend on the amount of nanoribbon bending. Furthermore, the value of conductance in the central gap for armchair case is more sensitive on the bending and magnetic field amounts with respect to zigzag case.

In this paper a silicon on insulator (SOI) photonic crystal waveguide with a triangular lattice of circular air holes for propagation of slow light has been investigated. The characteristics of the waveguide such as the normalized delay-bandwidth (NDBP), group index, and group velocity dispersion (GVD) have been simultaneously optimized by changing the waveguide width and infiltrating optical fluids in the first two rows of the air holes adjacent to the waveguide with different refractive indices n_1 and n_2. An improved NDBP ranged from 0.187 to 0.377 is obtained through changing the refractive indices of the two first rows. The high group index n_g=33.49 and low group velocity c/n_g through changing the width of PCW is obtained. These results are obtained by numerical simulation based on threedimensional plane wave expansion method.

The sun emits ultraviolet (UV), visible and infrared light, however siliconbased solar cells mainly absorb visible light. The employing of the quantum dots (QDs) is a way to increasing the efficiency of the solar cells. CdSe QDs absorb UV light and emit visible light, thus high-energy photons are converting to low-energy photons. In this paper, we simulated the characteristics of a quantum dot solar cell by means of FDTD method. The employing of the CdSe QDs reduced the surface reflectance and enhanced short-circuit current density and generation rate. The enhancement of PCE is 23.88% comparing to solar cell without QDs.