Current Nanoscience - Volume 8, Issue 5, 2012

MCM-41-SO3H as an ordered mesoporous silica material in which MCM-41 with covalently anchored sulfonic acid groups located inside the meso channels, was used as an acidic catalyst for the rapid and ‘green’ synthesis of N-aryl-2-amino-1,6-naphthyridine derivatives under solvent-free conditions. This nanocatalyst was characterized by X-ray powder diffraction, Fourier-transfer infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Nitrogen adsorption-desorption analysis and acid-base titration. This novel synthetic method is especially favoured because it provides a synergy of the nanosized MCM-41-SO3H and solvent-free conditions which offers the advantages of high yields, simplicity and easy workup compared to the conventional method reported in the literature. Most significantly, this solid acidic catalyst is found to be very efficient and reusabile for a number of times and showed consistent activity.

In this paper, glancing angle deposition technique (GLAD) has been used to grow cadmium telluride (CdTe) thin film by vacuum thermal method on glass substrates. During deposition, the substrate temperature was maintained at 20°C. Due to shadowing effect, the oblique angle deposition technique can produce nanorods tilted toward the incident deposition flux. The evaporated atoms arrive at the growing interface at a fixed angle Θ, measured from the normal to the substrate surface. An XRD picture, for nonfixed substrate an amorphous film has been seen at small angles (0°, 15°, 30°, 40°) has been obtained. Films deposited at large angles (50°, 60°, 65°, 70°, 80°, 85°) was found to be poly-crystalline in nature along the peak intensity direction. The surface morphology has shown an improvement without the presence of secondary phases for higher incident angles (Θ>60°). It has been observed that the use of this growth technique leads to an improvement in the optical properties of the films. The transmittance T and reflectance R spectra of CdTe films, deposited at different incident angles without substrate rotation have been obtained. High absorption coefficients (2x104- 8x104 cm-1) in the visible range and near-IR spectral range have been observed. Cell efficiency of 7.04 %, and fill factor of 70.6% have been obtained for CdTe thin films of thickness 450μm by GLAD technique, deposited at fixed substrate and incident angle 65°.

In this research, cadmium sulfide nanowires were successfully synthesized via a poly (ethylene glycol)-assisted solvothermal method using ethylenediamine solvent at 170°C for 3 days. In this procedure, cadmium nitrate and thiourea provided Cd2+ and S2- ions, respectively and polyethylene glycol 400 was used as a template. The effect of polymer gel concentration and solution stirring on the morphology, structural and optical properties of the products was investigated. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and UV-visible absorption spectroscopy. The results show that the length of the nanostructures grows longer with the increasing of the polymer gel concentration up to a certain value. The results also show that 1-D growth of CdS nanostructures depends solely on the quick stirring of the cadmium salt in the polymer gel. Hexagonal CdS nanowires with the average diameters of 75 nm and average lengths of 2.5 μm were obtained through the rapid stirring of the Cd2+-PEG 400 solution using a magnetic stirrer. The optimum amount of PEG 400 to provide the CdS nanowires was determined 5 g.

The hydrophobic SiO2 aerogels were prepared using sol-gel single-step process and surface processing method followed by ethanol supercritical drying, using tetraethoxysilane(TEOS) as silica source, ammonia as catalyst and vinyltriethoxysilane(VTES) as modifier. The effects were investigated on gelation time, contact angle with water by n(VTES)/n(TEOS). And the effects on adsorption capacity of alkyl compounds, benzene compounds and nitryl compounds of n(VTES)/n(TEOS), comparing with granular activated carbon (GAC) were also investigated. The hydrophobic SiO2 aerogels were investigated by video contact angle analyzer, Fourer transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption capacity was tested by the weight changing before and after soaking in the origin liquid. As results, with the increasing of n(VTES)/n(TEOS), gelation time increased, hydrophobic increased, the contact angle was higher to 157° when n(VTES)/n(TEOS) was 0.7. The SiO2 aerogels adsorption capacity was relevant with the surface tension of various organic liquid. The SiO2 aerogels adsorption capacity, when n(VTES)/n(TEOS) was 0.3, was average 9.64 times than that of GAC.

This article reviews our recent investigations on a general template-based approach for the preparation of one-dimension magnetic nanomaterials. The method involves the synthesis of a desired material within the pores of the ordered anodic aluminum oxide (AAO) membrane. The diameter, orientation, and crystal structure of ferromagnetic nanowires and nanotubes can be controlled using the AAO templates by changing deposition parameters in the process of direct-current electrochemical deposition. The corresponding magnetic properties can be controlled according to the structure and morphology of one-dimension magnetic nanomaterials. This kind of the ordered one-dimension magnetic nanomaterials with unique and tunable physical properties could be used in the fabrication of magnetic nanodevices with high performance and controllability.