Manoj Sharma

Synthesis, characterization, photocatalytic and reusability studies of capped ZnS nanoparticles

This paper presents results of a study on the structural and morphological properties of 2-mercaptoethanol (2-ME) capped ZnS nanoparticles (NPs). The photocatalytic and reusability study of the synthesized NPs to degrade dyes was also done. ZnS semiconductor NPs were synthesized via chemical precipitation route using 2-ME as a stabilizing agent. The as-prepared NPs were characterized by X-ray diffraction (XRD) technique to confirm the nanometer sized particle formation. Morphological features of capped ZnS NPs were determined by transmission electron microscopy (TEM). Dynamic light scattering (DLS) technique was used to determine the hydrodynamic size of capped ZnS NPs. UV-Vis studies were done to determine the absorption edge and bandgap of the capped ZnS NPs. Fourier transform infrared spectroscopy (FT-IR) studies were done to confirm the presence of 2-ME on the surface of NPs. Photocatalytic studies of the as-prepared ZnS NPs were done by taking Ponceau S and crystal violet dyes as model pollutants. Their comparative degradation behaviour has been discussed. Reusability study of ZnS NPs was done to ensure its applicability as recycled catalyst in photocatalysis. The result showed photocatalytic enhancement of reused catalyst. Possible reason has been discussed in this work.

Excitation Induced Tunable Emission in Ce3

Ce3+, Eu3+ ions singly doped, and Ce3+/Eu3+ codoped bismuth phosphate (BiPO4) nanophosphors were synthesized by a simple precipitation method and their structural, morphological, and photoluminescence properties were investigated. The structural and morphological analysis confirms the pure hexagonal crystal structure of the synthesized nanophosphors. From the Fourier transform infrared (FTIR) spectra various absorption bands respective to functional groups such as PO4 and phonon vibrations including the bending modes of the PO4 units are identified. The Ce3+ doped nanophosphors show spectrally broad luminescence in the blue (centred at 459u2009nm) wavelength region under the direct optical excitation of Ce3+ at 417u2009nm. For Eu3+ doped nanophosphors, five emission bands have been observed with 394u2009nm excitation wavelength. Among them, 595u2009nm has shown bright yellowish-orange emission. These results demonstrate that by appropriately tuning the excitation wavelength of these codoped nanophosphors the emission color in the visible region (blue and orange) can be flexibly controlled in a single sample without varying its chemical composition and size. The mechanism for this excitation energy dependent tunable emission is explained on the basis of nonenergy transfer (ET) occurring among Ce3+/Eu3+ dopant ions.

Mercaptopropionic acid capped ZnS:Mn/ZnS core/shell quantum dots as fluorescence probe for folic acid detection

In this work, high quality 3-mercaptopropionic acid (MPA) capped ZnS:Mn/ZnS quantum dots (QDs) have been synthesized via chemical precipitation approach. Structure analysis done by XRD and TEM shows that the prepared QDs are mono-dispersed with with a size distribution of 3-5nm. Optical features of the core/shell QDs have been characterized by UV-Visible spectroscopy and photoluminescence spectrometer (PL). The addition of folic acid (FA) to ZnS:Mn/ZnS QDs solution leads to a linear range of quenching of PL with the concentration of FA from 2μM/L to 60μM/L. It thus provides an opportunity to apply MPA capped ZnS:Mn/ZnS QDs as a sensitive fluorescence probe for FA detection. The detection limit is 0.48μM/L. The fluorescence quenching mechanism caused by FA was also studied.

Effect of pH on Size of ZnS Nanoparticles and Its Application for Dye Degradation

This paper presents the results from a study related to the effect of solution pH on particle size and photocatalytic properties of ZnS nanoparticles (NPs). ZnS NPs capped with 2-Mercaptoethanol (2-ME) have been synthesized via chemical precipitation route at different pH values, i.e., 8, 10, and 12. Effect of solution pH on particle size of NPs has been studied by the Dynamic Light Scattering (DLS) technique. A comparison of the results obtained from the DLS technique for ZnS NPs synthesized at different pH values showed narrower particle size distribution as we go from higher pH value, i.e., 12, to lower pH value, i.e., 8. Fourier Transform Infrared Spectroscopy (FTIR) has been carried out to study the presence of hydroxyl groups and 2-ME on the surface of NPs. Comparative photocatalytic study of these NPs has also been carried out using Ponceau S dye.

Highly luminescent ZnS:Mn/ZnS core shell nanoparticles for solid state lightning

This paper presents some results from a study of luminescent properties of core shell zinc sulphide (ZnS) nanoparticles (NPs) with the Mn doped core and ZnS as the shell. Influencing factors like core shell structure and dopant concentration are tuned to investigate the effects on their luminescent properties. Results indicate that these luminescent nanoparticles potentially can be used in LEDs.

Luminescent properties of nano-sized Y2O3:Eu synthesized by co-precipitation method

Y2O3:Eu3+ phosphor is one of the most promising oxide-based red phosphors. It is being studied since long time because of its efficient luminescence under ultraviolet (UV) and cathode-ray excitation. Y2O3:u2009Eu3+ show luminescent properties and emits red light at a wavelength of 611 nm and was found to be suitable for many display devices. The present study focuses on the preparation, characterization and structural properties of Eu+3 doped Y2O3 nanoparticles obtained by co-precipitation method. The synthesized particles were characterized by X-ray diffraction (XRD), UV visible spectroscopy, Transmission electron microscopy (TEM) and Photoluminescence. All the powders were well crystallized spherical particles with average crystallite size of 85nm. An optimum concentration of 5 mol% Eu3+ doping exhibited maximum optical properties.

Synthesis and characterization of zinc doped nano TiO{sub 2} for efficient photocatalytic degradation of Eriochrome Black T

Sol-gel method was used to synthesize undoped and zinc doped TiO2 with varied dopant concentrations using titanium tetraisopropoxide and zinc acetate as precursors. The synthesized catalyst samples were characterized by various techniques such as X-ray powder diffraction (XRD), UV-vis diffuse reflectance (DRS). The photocatalytic activity was determined by means of degradation of azo dye Eriochrome Black T. The results revealed that Zn doped TiO2 nanoparticles exhibited better results as compared to undoped TiO2 nanoparticles. Zn doped TiO2 (0.7mol %) nanoparticles exhibited the highest photocatalytic activity.

Optical and Morphological Studies of Doped Core Shell ZnS:Cu/ZnS Nanoparticles

The paper presents some results of study based on applications of ZnS core shell quantum dots (QDs) doped with Cu. Keeping the luminous properties in focus we synthesized the core shell QDs by chemical precipitation route, resulting in formation of core@shell QDs with ZnS core doped with copper and ZnS shell on it, i.e. [ZnS:Cu@Zn. We focus the application of these particles in field of OLEDs (AMOLED) to address the performance deficiencies like varying brightness of the different wavelength emitting LEDs, called Green Window problem. Efforts have been done to address the problems by synthesizing highly luminescent green emitting copper doped ZnS, core@shell QDs. Further a monolayer of core shell quantum dots was deposited on ITO by spin coating for analyzing the photometric properties of the QDs.