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Fe doped ZnS nanoparticles (Zn1-xFexS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, UV-Vis and photoluminescence spectrometer. The X-ray diffraction and transmission electron microscope studies show that the size of crystallites is in the range of 2-5 nm. Photocatalytic activities of ZnS and 3, 5 and 10 mol% Fe doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Fe doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to ultraviolet light. The optimal Fe/Zn ratio was observed to be 3 mol% for photocatalytic applications., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Mn-doped TiO(2) nanoparticles (Ti(1-)(x)Mn(x)O(2); where x=0.00-0.10) were synthesized by sol-gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV-Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and measurements show that the size of crystallites is in the range of 10-20 nm. Optical measurements indicated a red shift in the absorption band edge after Mn doping. Direct allowed band gap of undoped and Mn-doped TiO(2) nanoparticles measured by UV-Vis spectrometer were 3.00 and 2.95 eV at 300 °C, respectively. Photocatalytic activities of TiO(2) and Mn doped TiO(2) were evaluated by irradiating the sample solution of methylene blue (MB) dye under ultraviolet and visible light exposure. It was found that Mn-doped TiO(2) bleaches MB much faster than undoped TiO(2) upon its exposure to the visible light as comparison to ultraviolet light. The experiment demonstrated that the photodegradation efficiency of Mn-doped TiO(2) was significantly higher than that of undoped TiO(2) upon its exposure to visible light., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Aims: Silver nanoparticles exhibit unique antibacterial properties that make these ideal candidates for biological and medical applications. We utilized a clean method involving a single synthetic step to prepare silver nanoparticles that exhibit antimicrobial activity., Materials & Methods: These nanoparticles were prepared by reducing silver nitrate with diaminopyridinylated heparin (DAPHP) and hyaluronan (HA) polysaccharides and tested for their efficacy in inhibiting microbial growth., Results & Discussion: The resulting silver nanoparticles exhibit potent antimicrobial activity against Staphylococcus aureus and modest activity against Escherichia coli. Silver-HA showed greater antimicrobial activity than silver-DAPHP, while silver-glucose nanoparticles exhibited very weak antimicrobial activity. Neither HA nor DAPHP showed activity against S. aureus or E. coli., Conclusion: These results suggest that DAPHP and HA silver nanoparticles have potential in antimicrobial therapeutic applications.

We report a simple, eco-friendly facile wet chemical nitrate precursor route for the synthesis of pristine and nickel-containing nanocrystalline (∼44 nm) α-Fe2O3. Thermal analysis of the dried (∼70 °C) presumed oxalate powder, Fe2(C2O4)3 · 4H2O (also confirmed by X-ray diffraction), revealed two-step formation of the oxide; slower reaction as Fe2(C2O4)3 · 4H2O↓ → 4H2O↑ + 2CO2↑ + 2FeC2O4↓ and faster as 2FeC2O4 → Fe2O3↓ + CO2↑ + 3CO↑. The incorporation of nickel resulted in progressive increase of cell parameters and exhibited decrease in estimated direct and indirect band gap values. The direct band gap values were in close correlation with emission transitions. The direct nature and narrowing of band gap with nickel addition ensures the higher absorbance values and wider spectrum of absorbance; indicating the enhanced semiconducting properties for applications such as solar cells, photocatalytic activity, etc. Regarding magnetic properties, the saturation magnetization increased progressively with nickel content while coercivity reduced up to 2 wt% of Ni content and increased afterward. The resistivity values with nickel incorporation decreased, when substituted at Fe3+ sites. [ABSTRACT FROM AUTHOR]

Abstract: Cu doped ZnS nanoparticles (Zn1−x Cu x S; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope, ultraviolet-visible and photoluminescence spectrometer. The X-ray diffraction and high resolution transmission electron microscope studies show that the size of crystallites is in the range of 2–10nm. XRD study revealed that the samples are composed of cubic phase without doping and at 3mol% Cu doping concentration while at the doping of 5mol% and 10mol% Cu, phase transition from cubic blende to hexagonal phase occurs in ZnS. Photocatalytic activities of ZnS and 3, 5 and 10mol% Cu doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Cu doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to the ultraviolet light. The optimal Cu/Zn ratio was observed to be 3mol% for photocatalytic applications. [Copyright &y& Elsevier]

Abstract: Fe doped CdS nanoparticles (Cd1−x Fe x S; where x =0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman and UV–vis spectrometer. The XRD and TEM measurements show that the size of crystallites is in the range of 2–10nm. With increased the Fe doping concentration, the position of the Raman bands shifted towards higher wavenumbers and their intensities decreased drastically. Optical measurements indicated that the absorption band edge shifted towards longer wavelength upon Fe doping. Direct allowed band gap of undoped and Fe doped CdS nanoparticles measured by UV–vis spectrometer were 2.3 and 2.2eV at 100°C, respectively. Photocatalytic activities of CdS and Fe doped CdS were evaluated by irradiating the solution of methylene blue (MB) and sample under visible light. It was found that Fe doped CdS bleaches MB much faster than undoped CdS upon its exposure to the visible light. The optimum Fe/Cd ratio was observed to be 3mol% for photocatalytic applications. In contrast, little degradation was observed for the pure CdS powder. [Copyright &y& Elsevier]

Nanocrystals of undoped and nickel-doped zinc oxide (ZnNiO, where x = 0.00-0.05) were synthesized by the coprecipitation method. Crystalline size, morphology, and optical absorption of prepared samples were determined by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and UV-visible spectrometer. XRD and SEM studies revealed that Ni-doped ZnO crystallized in hexagonal wurtzite structure. Doping of ZnO with Ni was intended to enhance the surface defects of ZnO. The incorporation of Ni in place of Zn provoked an increase in the size of nanocrystals as compared to undoped ZnO. Crystalline size of nanocrystals varied from 10 to 40 nm as the calcination temperature increased. Enhancement in the optical absorption of Ni-doped ZnO indicated that it can be used as an efficient photocatalyst under visible light irradiation. Optical absorption measurements indicated a red shift in the absorption band edge upon Ni doping. The band gap value of prepared undoped and Ni-doped ZnO nanoparticles decreased as annealing temperature was increased up to 800 °C. [ABSTRACT FROM AUTHOR]

Nanoparticles of undoped and manganese doped zinc sulphide (Zn1-xMnxS, where x = 0.00, 0.03, 0.05 and 0.10) were synthesized by chemical precipitation method. Structural characterization of as synthesized semiconductor nanoparticles were performed by X ray diffraction pattern (XRD) while optical characterization were done by UV-Visible absorption spectroscopy. XRD pattern showed that the synthesized Mn doped ZnS nanoparticles have cubic structure with 3-4 nm average crystallite size. Optical absorption measurements indicated red shift in the absorption band edge upon Mn doping. Direct allowed band gap of undoped and Mn- doped ZnS nanoparticles measured by UVVIS spectro-photometer were 2.95 to 2.85 eV at 400°C. [ABSTRACT FROM AUTHOR]

Developing bactericidal coatings using simple green chemical methods could be a promising route to potential environmentally friendly applications. Here, we describe an environmentally friendly chemistry approach to synthesize metal-nanoparticle (MNP)-embedded paint, in a single step, from common household paint. The naturally occurring oxidative drying process in oils, involving free-radical exchange, was used as the fundamental mechanism for reducing metal salts and dispersing MNPs in the oil media, without the use of any external reducing or stabilizing agents. These well-dispersed MNP-in-oil dispersions can be used directly, akin to commercially available paints, on nearly all kinds of surface such as wood, glass, steel and different polymers. The surfaces coated with silver-nanoparticle paint showed excellent antimicrobial properties by killing both Gram-positive human pathogens (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). The process we have developed here is quite general and can be applied in the synthesis of a variety of MNP-in-oil systems. [ABSTRACT FROM AUTHOR]

The one-step electrostatic complexation, reduction of aqueous chloroplatinate ions, and capping of the platinum nanoparticles thus formed by hexadecylaniline Langmuir monolayers is described. The capping of the platinum nanoparticles formed spontaneously at the air–water interface by hexadecylaniline enables their facile transfer as multilayers onto suitable solid substrates by the Langmuir–Blodgett technique. The real-time reduction of the aqueous chloroplatinate ions at the air–water interface was followed by measurement of the pressure–area isotherms, while the multilayer Langmuir–Blodgett films were characterized by quartz crystal microgravimetry, transmission electron microscopy, electron diffraction, and X-ray photoemission spectroscopy. [Copyright &y& Elsevier]

We demonstrate the phase transfer of silver nanoparticles synthesized in an aqueous medium into hexane containing the cationic surfactant octadecylamine (ODA). During vigorous shaking of the biphasic mixture, rapid phase transfer of the silver nanoparticles into the organic phase was observed. The phase transfer of the silver nanoparticles arises due to coupling of the silver nanoparticles with the ODA molecules present in organic phase via either coordination bond formation or weak covalent interaction. This process renders the nanoparticles sufficiently hydrophobic and dispersible in the organic phase. The ODA-stabilized silver nanoparticles could be separated out from the organic phase in the form of a powder and are readily redispersible in different organic solvents. The nature of binding of the ODA molecules to the silver nanoparticle surface was characterized using UV–vis spectroscopy, thermogravimetry, transmission electron microscopy, nuclear magnetic resonance spectroscopy, X-ray photoemission spectroscopy, and Fourier transform infrared spectroscopy. [Copyright &y& Elsevier]

The organization of hydrophobized colloidal gold nanoparticles at air–water interface and the formation thereafter of lamellar, multilayer films of the gold nanoparticles by the Langmuir–Blodgett technique is described in this paper. The hydrophobization of the colloidal particles was accomplished by the direct chemisorption of laurylamine molecules on aqueous colloidal gold nanoparticles during a phase-transfer process. While monolayers of the laurylamine-capped gold nanoparticles at the air–water interface were not amenable to layer-by-layer transfer onto solid supports, it was observed that addition of the water-insoluble amphiphile octadecanol to the gold nanoparticle solution improved the stability of the monolayer at the interface as well as the multilayer assembly protocol. The organization of the gold nanoparticles at the air–water interface was followed by surface pressure–area isotherm measurements while the formation of multilayer films of the nanoparticles by the Langmuir–Blodgett technique was monitored by quartz crystal microgravimetry, UV–vis spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. [Copyright &y& Elsevier]

• Green photo-catalyst was prepared using turmeric roots. • No chemical precursor has been used in the process of photocatalyst preparation. • Degradation of pesticide pollutants: carbofuran and malathion. • Turmeric roots powder will be promoted as an efficient eco-friendly photo-catalyst. Photocatalysis using naturally occurring fibre materials have been rarely investigated before. In this article, preparation of turmeric roots powder via a straight forward green process to obtain an eco-friendly photo-catalyst is reported. No precursor chemical was used for the preparation. Morphology, composition (elements present) and optical properties of the obtained powder were studied. Here, for the first time photo-catalytic degradation of toxic pesticides pollutants present in aqueous solution was explored using eco-friendly 'turmeric roots' photo-catalyst. Presently, carbofuran and malathion; commonly used pesticides in the region were considered as pollutants in water. Overall, based on the analyzed outcomes, turmeric powder will be promoted as a prospective novel green photo-catalyst to substitute hazardous chemical-based photo-catalyst in the field of environmental photo-catalysis especially for the degradation of pesticides toxicity present in ponds water. [ABSTRACT FROM AUTHOR]

Nanoparticles of silver and nickel were grown in thermally evaporated fatty acid (stearic acid) films by immersion of the film sequentially in solutions containing Ag[sup +] ions and Ni[sup 2+] ions. Attractive electrostatic interaction between the metal cations and the carboxylate ions in the fatty acid film leads to entrapment of the cations in the film. Thereafter, the metal ions were reduced in situ to yield nanoparticles of Ag and Ni of ∼30 nm diameter within the fatty acid matrix. Thermal treatment of the stearic acid-(silver+nickel) nanocomposite films led to the formation of a Ni–Ag alloy at ∼100 °C. Prolonged heat treatment at this temperature resulted in the phase separation of the alloy and the reformation of individual Ag and Ni nanoparticles. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The assembly of nanoparticles in topologically predefined superstructures is an important problem in the area of nanoscale architecture. In this letter, we demonstrate the electrostatic assembly of lysine-capped colloidal gold particles on drop-coated DNA films. Electrostatic interaction between the positive charges on the gold nanoparticles and the negative charges on the phosphate groups of the DNA template molecules leads to the assembly of the gold nanoparticles in linear superstructures. The use of DNA as templates for the assembly of nanoparticles shows promise for extension to more complex geometries through rational design of the DNA base sequences as well as in the realization of nanowires by stringing together metal nanoparticles. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report a simple, eco-friendly facile wet chemical nitrate precursor route for the synthesis of pristine and nickel-containing nanocrystalline (∼44 nm) α-Fe2O3. Thermal analysis of the dried (∼70 °C) presumed oxalate powder, Fe2(C2O4)3 · 4H2O (also confirmed by X-ray diffraction), revealed two-step formation of the oxide; slower reaction as Fe2(C2O4)3 · 4H2O↓ → 4H2O↑ + 2CO2↑ + 2FeC2O4↓ and faster as 2FeC2O4 → Fe2O3↓ + CO2↑ + 3CO↑. The incorporation of nickel resulted in progressive increase of cell parameters and exhibited decrease in estimated direct and indirect band gap values. The direct band gap values were in close correlation with emission transitions. The direct nature and narrowing of band gap with nickel addition ensures the higher absorbance values and wider spectrum of absorbance; indicating the enhanced semiconducting properties for applications such as solar cells, photocatalytic activity, etc. Regarding magnetic properties, the saturation magnetization increased progressively with nickel content while coercivity reduced up to 2 wt% of Ni content and increased afterward. The resistivity values with nickel incorporation decreased, when substituted at Fe3+ sites. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the structural and optical properties of zinc oxide nanoparticles synthesized by hydrothermal method at different selected pH values ranging from 7 to 11 are presented. The synthesized nanoparticles are characterized for structural properties by X-ray diffractrometer and transmission electron microscope and the optical properties are carried out through UV–Visible spectrophotometers, photoluminescence and Raman spectroscopy. The X-ray diffractrometer pattern indicates the pure phase formation of ZnO and transmission electron microscope images show that the particle size varies from 63 to 23nm for samples synthesized at different pH values ranging from 7 to 11, respectively. Raman and Photoluminescence spectrum also confirm the phase formation of ZnO. Moreover, the optical band gaps calculated through UV spectroscopy are found to be increases from 5.57 (±0.02) to 5.79 (±0.02)eV for samples synthesized at different pH values ranging from 7 to 11, respectively. [Copyright &y& Elsevier]

Abstract: Nanoparticles of various transition elements such as palladium, iron, and nickel were synthesized in situ in the polydimethylsiloxane (PDMS) matrix by thermal decomposition of their corresponding acetylacetonate salts. Various complementary techniques such as XRD, TEM and XPS were used to characterize the nanoparticles formed in the polymer matrix. This synthesis route results in relatively monodisperse nanoparticles with a narrow particle size distribution. In addition, the composite films are pore-free and mechanically stable, making them attractive for a range of applications. Palladium-PDMS membranes can be used as catalytic membrane reactors and show enhanced catalytic activity in ethylene hydrogenation. [ABSTRACT FROM AUTHOR]