Bandgap engineering of colloidal zinc oxysulfide via lattice substitution with sulfur.

Zinc oxysulfide nanocrystals with zinc blende phase are synthesized through a wet-chemical method. An affirmation of the crystal structure, elemental homogeneity and phase transformation is obtained by X-ray diffraction and authenticated by electron micrographic studies. Theoretical observations have strongly supported the thermodynamic solubility limit for its (30%) formation. An anomalous bandgap bowing with modulation in bandgap from 3.74 eV (ZnO) to 3.93 eV (ZnS) was observed with a minimum bandgap of 2.7 eV. Tunable bandgap and a wide range of visible emission ascertain it as a potential material for optoelectronic and solar cell applications due to its large bandgap offsets.

A new class of PANI-Ag core-shell nanorods with sensing dimensions.

A single-step, cost-effective and eco-safe synthesis of a new class of homogeneous silver-polyaniline (PANI-Ag) core-shell nanorods is carried out via mild photolysis by ultraviolet radiation from sunlight (SUN UV-radiation). X-ray diffraction (XRD) of these core-shell nanorods gives two additional peaks from PANI centered at 2θ = 20.5° and 24. 9°. A validation of the core-shell structural information is given by transmission electron spectroscopy (TEM) whereas the tubular shape morphology is determined by scanning electron microscopy (SEM). UV-Vis. absorption shows a strong blue-shift along with photoluminescence emission. Fourier transform-infrared spectroscopy (FT-IR) and energy dispersive X-ray spectroscopy (EDX) also support the core-shell formation. Thermogravimetric analysis (TGA) shows good thermal stability and allows excellent detection of hydrogen peroxide and hydrazine. The cyclic voltammetry (CV) results show excellent electro-activation, indicating its promising potential in sensing of clinical and environmental analytes.

Green synthesis of nanosilver as a sensor for detection of hydrogen peroxide in water.

Present "green" synthesis is an efficient, easy-going, fast, renewable, inexpensive, eco-friendly and non-toxic approach for nanosilver formation, which offers numerous benefits over physiochemical approaches. The X-ray diffraction (XRD) pattern suggests the formation and crystallinity of nanosilver. The average particle size of silver nanoparticles was 8.25±1.37 nm as confirmed by transmission electron microscopy (TEM). The UV-vis absorption spectrum shows a characteristic absorption peak of silver nanoparticles at 410 nm. FTIR confirms Azadirachtin as reducing and stabilizing agent for nanosilver formation. In addition, the nanosilver modified electrode (Ag/GC) exhibited an excellent electro-catalytic activity toward the reduction of hydrogen peroxide (H(2)O(2)). The produced nanosilver is stable and comparable in size. These silver nanoparticles show potential applications in the field of sensors, catalysis, fuel cells and nanodevices.

Growth mechanism and photoluminescence property of flower-like ZnO nanostructures synthesized by starch-assisted sonochemical method.

Flower-like ZnO nanostructures have been synthesized by starch-assisted sonochemical method and the effect of starch and ultrasound on the formation of ZnO nanostructure has been investigated. It is observed that starch and ultrasonic wave both plays a vital role on the growth of ZnO nanostructure. X-ray diffraction (XRD) pattern indicated that the synthesized flower-like ZnO nanostructures were hexagonal. FTIR spectrum confirms the presence of starch on the surface of flower-like ZnO nanostructure. The photoluminescence spectrum of flower-like ZnO nanostructure consists of band-edge emission at 393nm as well as emission peaks due to defects. On the basis of structural information provided by X-ray diffraction (XRD) and morphological information by Scanning Electron Microscopy (SEM), a growth mechanism is proposed for formation of flower-like ZnO nanostructures. Differential Scanning Calorimetry (DSC) of starch in liquid medium confirms that gelatinization is a two step process involving two phases.

Growth mechanism and optical property of CdS nanoparticles synthesized using amino-acid histidine as chelating agent under sonochemical process.

Using amino-acid histidine as chelating agent, CdS nanoparticles have been synthesized by sonochemical method. It is found that by varying the ultrasonic irradiation time, we can tune the band gap and particle size of CdS nanoparticles. The imidazole ring of histidine captures the Cd ions from the solution, and prevents the growth of the CdS nanoparticles. The deviation in the linear relation in between cube of radius of nanoparticles and ultrasonic irradiation time confirms the growth of CdS nanoparticles occur via two process; one is the diffusion process of the reactants as well as reaction at the surface of the crystallite. CdS nanoparticles synthesized using histidine as organic chelating agent have band edge emission at approximately 481 nm and have greater photoluminescence intensity with blue-shift to higher energy due to typical quantum confinement effect.

Growth mechanism and optical property of ZnO nanoparticles synthesized by sonochemical method.

ZnO nanoparticles have been synthesized by ultrasonic irradiation of an aqueous-alcoholic/aqueous-alcoholic-ethylenediamine (EDA) solutions of zinc nitrate and sodium hydroxide. ZnO nanoparticles possess hexagonal wurtzite structures and they exhibit special photoluminescence properties with a red-shift of 22 nm in UV emission band. It is found that the ultrasonic irradiation time and the solvents both influence the growth mechanism and optical properties of ZnO nanoparticles. The possible growth mechanism of ZnO nanoparticles formation by sonochemical method has been tried to discuss.