Simple Chemical Precipitation Research Articles

Structural and optical properties of Zn doped CdO nanoparticles synthesized by chemical precipitation method

In this article, synthesis of undoped and zinc doped cadmium oxide with different zinc concentration (0, 2, and 5 wt%) using simple chemical precipitation method has been discussed. Influence of zinc dopant on crystal structure, microstructure and optical properties of the nanoparticles was investigated by means of X-ray diffractometer, field emission scanning electron microscope, ultraviolet–visible spectrometer, and photoluminescence spectrometer. Crystal structure analysis reveals that zinc doping appreciably increases the crystalline size and also it shows the polycrystalline nature of the samples. Microstructural investigation shows that the samples contain nanoparticles. Optical bandgap of the prepared samples found to vary from 2.67 to 2.61 eV for various dopant concentrations. With these specifications we can fabricate semiconductor nanocrystals and these can be used for some large scale applications of nanotechnology.

Photocatalytic degradation of brilliant green using undoped and Zn doped SnO2 nanoparticles under sunlight irradiation

We formulate a simple chemical precipitation method for the preparation of undoped and Zn doped SnO2 nanocrystals. The X-ray diffraction (XRD) patterns revealed the crystalline nature of the prepared products. The diffusion reflectance spectra (DRS) show the optical properties and confirmation made by photoluminescence (PL) results. The scanning electron microscope (SEM) and transmission electron microscopic (TEM) results discussed more regarding the morphologies of the products. The photocatalytic performance of SnO2 studied by the degradation of brilliant green showed excellent activity on 0.075M of zinc doping due to its reduced crystallite size and high surface area.

Stability of Tungsten Oxide Nanoparticles in Different Media

Tungsten oxide (WO3) nanoparticles were synthesised by a simple chemical precipitation method in various media, such as acidic, basic and neutral. Hydrochloric acid and sodium hydroxide were used to maintain the different pH levels and tungstic acid was used as the precursor for the synthesis of tungsten oxide. The resultant nanoparticles were studied by different characterisation techniques. Powder X-ray diffraction shows that the average crystallite size of the WO3 is about 13 nm and exhibits stable orthorhombic phase for different pH values. Particle size and the surface morphology of the synthesised material were studied by TEM analysis. Chemical composition and surface area of the nanoparticles were studied by FTIR and BET measurements. Optical properties of the synthesised nanoparticles were studied by UV-Vis absorption and photoluminescence spectroscopy. Band gap (~2.7 eV) of the synthesised WO3 was investigated from the optical absorption spectra. At room temperature, a strong PL blue emission peak at ~440 nm was observed for the synthesised tungsten oxide nanomaterials. Thermal stability of the synthesised material was studied by TG/DTA analysis. Cyclic voltammetry illustrated the electrochemical response of the WO3 nanoparticles using KCl as electrolyte. The peak separation of 182 mV, 153 mV and 77 mV for the acidic, basic and neutral media were observed. Thus it was confirmed that, tungsten oxide has a low peak separation, a fast reaction rate and electron transfer rate in neutral medium.

Photo-degradation of organic dyes: simple chemical synthesis of Ni(OH)2 nanoparticles, Ni/Ni(OH)2 and Ni/NiO magnetic nanocomposites

In this work Ni, Ni(OH)2, NiO nanoparticles as well as Ni/Ni(OH)2 and Ni/NiO nanocomposites were synthesized via a simple chemical precipitation method in aqueous solution. The prepared products were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. Alternating gradient force magnetometer (AGFM) illustrated ferro-magnetic behaviour of Ni nanoparticles as well as Ni/Ni(OH)2 and Ni/NiO nanocomposites. The photocatalytic behaviour of Ni–NiO nanocomposites was evaluated using the degradation of organic dyes under ultraviolet light irradiation. The results show that Ni–NiO nanocomposites have applicable magnetic and photocatalytic performance.

Synthesis of the graphene-ZnTiO3 nanocomposite for solar light assisted photodegradation of methylene blue

Cubic and hexagonal phase zinc titanate (ZT) nanoparticles were synthesized via simple chemical precipitation method. The graphene-zinc titanate (GZT) nanocomposites were prepared by using the synthesized ZT nanoparticles and graphene oxide as precursors. The synthesized materials were characterized by various spectroscopic techniques. The agglomerated ZT nanoparticles anchored on graphene sheets are clearly visible in the field emission scanning electron micrograph (FE-SEM) image. Raman mapping of the GZT nanocomposites revealed the homogeneity and distribution of ZT nanoparticles on the surface of graphene. The UV–visible absorption and photoluminescence spectra of the samples suggest that the GZT nanocomposites can be used as efficient photocatalysts to remove organic dye from water. The photocatalytic activity of the synthesized photocatalysts was evaluated by the photodegradation of methylene blue dye under sunlight irradiation. The enhanced absorption in the visible region of the GZT samples compared to the ZT samples played a vital role during the photocatalysis. The hexagonal phase GZT nanocomposite displayed remarkable photocatalytic activity compared to the bare ZT nanoparticles. The possible electron transfer mechanism for graphene-ZT interface during the photocatalysis process is also proposed. Furthermore, the reusability and stability tests for the prepared photocatalysts were made and reported.

Investigation on the structural, optical, morphological and magnetic properties of undoped and Cd doped CuO nanoflakes

Presented here is the cadmium doped CuO nanoflakes prepared via a simple chemical precipitation method at room temperature. The results of X-ray line broadening exhibit the crystalline nature of the prepared products. X-ray photoelectron spectroscopy showed the bivalent nature of copper. The functional groups of the samples were identified by Fourier transform infrared spectroscopy. UV–Visible absorption and photoluminescence measurements reveal the optical properties of the products. The formation of CuO nanoflakes can be seen by field emission scanning electron microscopy and confirmed by transmission electron microscopy. The susceptibility measurements show the enhanced ferromagnetic behaviour of CuO with the cadmium doping.

Effect of nickel doping on structural and optical properties of ZnS nanoparticles

In the present work, solution based simple chemical precipitation method has been used to prepare undoped and Ni-doped ZnS nanoparticles. Zinc acetate, sodium sulfide, and nickel nitrate have been used as precursors for the preparation of Ni-doped ZnS nanoparticles. The X-ray diffraction results revealed that the undoped and Ni-doped ZnS nanoparticles exhibit hexagonal Structure. The average grain size of the prepared nanoparticles was found to lie in the range of 2.6–4.2nm. The SEM images show that the particles have smooth surface and the formation of agglomerated nanoparticles. The compositional analysis results confirm the presence of Ni, Zn and S in the prepared samples. The optical properties of undoped and Ni-doped ZnS quantum dots have been studied using absorption spectra. HRTEM results show that undoped and Ni-doped ZnS nanoparticles exhibit a uniform size distribution with average grain size lying in the range of 2.3–3.6nm. The synthesized nanoparticles exhibited an emission peak centered at around 612nm in the PL spectrum.

Preparation of octahedral Cu2O nanoparticles by a green route

The fabrication of octahedral Cu2O was described by a green and simple chemical precipitation method in this study. All samples were characterized by X-ray powder diffractometer(XRD), scanning electron microscopy(SEM), Fourier transform infrared spectrometer (FTIR) and ultraviolet–visible spectrophotometer (UV–vis), respectively. The results show that products are composed of octahedral particles with an edge length of 200–300nm, and narrow band gaps (2.26eV), which is blue shifted with respect to the bulk Cu2O value (2.17eV). Well-dispersed Cu2O with effectively absorbing visible light can be obtained through the route which is surfactant-free, cost effective, and suitable for large scale production.

Iron oxide-impregnated dextrin nanocomposite: synthesis and its application for the biosorption of Cr(VI) ions from aqueous solution

In this paper, iron oxide impregnated with dextrin (Dex-Fe3O4) nanocomposite was synthesized by simple one-step hydrothermal chemical precipitation reaction. The nanocomposite was characterized by XRD, FT-IR, TGA, DTG, SEM with EDX and TEM techniques. The material was further explored as an adsorbent for the removal of Cr(VI) ions from its aqueous solution. The optimum removal of Cr(VI) ions with the highest adsorption capacity of 17.8 mg g−1 was observed at pH 2. The equilibrium data were analysed with Langmuir, Freundlich, D–R and Temkin isotherms model and data were best followed by Langmuir model and Temkin model with a maximum monolayer adsorption capacity of 51.28, 54.64, and 71.43 mg g−1 at 30, 40, and 50°C, respectively. The activation energy calculated by D–R model reveals that the adsorption process is chemisorption in nature. The experimental data were best fitted with pseudo-second-order. The results of thermodynamic parameters (ΔG°, ΔH°, and ΔS°) showed that the adsorption of Cr(VI) on Dex-Fe3O4 is endothermic spontaneous in nature. The synthesized nanocomposite material is very promising for the removal of Cr(VI) from aqueous solution.

Photoluminescence and photocatalytic studies of metal ions (Mn and Ni) doped ZnS nanoparticles

The present study deals with the structural, optical and photocatalytic studies of thioglycerol capped doped ZnS nanoparticles (NPs). Effect of two dopant metal ions (Ni and Mn) on photoluminescence emission and photocatalytic properties have been studied in detail. Zn1−xMxS; M=Ni or Mn; x=0, 0.01, 0.02, 0.03 and 0.04 NPs have been synthesized using simple chemical precipitation route. Structural and morphological studies have been done by using X-ray diffraction (XRD) technique and high resolution transmission electron microscopy (HRTEM). Capping of thioglycerol on the surface of doped ZnS has been confirmed by Fourier transform infrared (FTIR) studies. UV–Vis and photoluminescence studies have been carried out to study the effect of doping on optical properties of synthesized materials. Degradation of crystal violet has been carried out with the aim to investigate the effect of Ni or Mn doping on photocatalytic activity of ZnS. It has been observed that both the metal ions have decreased the photocatalytic activity of ZnS. The effect of photocatalytic reaction temperature on photocatalytic properties of one of the doped sample has also been investigated. It has been interpreted from the results that photocatalytic activity of doped semiconductor nanostructures is strongly dependant on their photoluminescence properties as well as on photocatalytic reaction temperature.

Methyl orange adsorption onto simple chemical route synthesized crystalline α-Fe2O3 nanoparticles: kinetic, equilibrium isotherm, and neural network modeling

Nanoparticles of α-Fe2O3 were synthesized by simple chemical precipitation method and characterized by X-ray diffraction study, scanning electron microscopy, and Fourier transform infrared spectroscopy. Feasibility of as-synthesized nanoparticles was investigated for adsorptive removal of methyl orange (MO) dye from aqueous solution. The effects of various experimental parameters such as solution pH, initial MO concentration, contact time, and α-Fe2O3 nanoparticles dose were studied in batch mode. More than 90% removal was reported at pH 2.0 with 30 mg L−1 initial MO concentration treated with 1.00g L−1 adsorbent dose. Isotherm study reveals that Langmuir isotherm model is the most efficient one in explaining the process and maximum adsorption capacity as much as 28.90 mg g−1 is reported. Kinetic study shows that the adsorption process is best explained by second-order kinetic model confirming the dominancy of chemisorption in the process. Subsequently, the experimental data were modeled by artificial neural network to predict the removal efficiency of MO by α-Fe2O3 nanoparticles following conduction of 95 experimental data points. A three-layer feed-forward back-propagation model with Levenberg–Marquardt algorithm was developed which show that the optimal network topology is 4–10–1. Model predicted data shows very good agreement with experimental data set with mean squared error and coefficient of determination (R2) as 0.00152 and 0.9916, respectively.

Structural and Optical Properties of White Light Emitting ZnS:Mn(2+) Nanoparticles at Different Synthesis Temperatures.

We report of the synthesis and characterisation of white emitting ZnS:Mn(2+) nanoparticles. The spectroscopic properties and the crystal structure of Mn doped ZnS nanoparticles are studied here to provide a better understanding on how the luminescence emission and the crystalline composition are influenced by the synthesis temperature. The synthesis of the samples were carried out by the simple wet chemical precipitation method. The influence of synthesis temperature on structure and optical properties were studied at constant Mn concentration. The nanoparticles were structurally characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD studies show the phase singularity of Mn doped ZnS particles having zinc-blende (cubic) structure at all temperatures. The band gap of the doped samples are red shifted with temperature. Electron Paramagnetic Resonance (EPR) spectra exhibited resonance signals, characteristic of Mn(2+). Incorporation of Mn in the ZnS nanoparticles was confirmed by Inductively Coupled Plasma- Atomic Emission Spectroscopic studies (ICP-AES). The samples show an efficient emission of yellow-orange light centred at 590nm which is characteristic of Mn(2+) along with a blue emission at 435nm due to sulfur vacancy. The overall emission is white at all temperatures with CIE co-ordinates in close agreement with achromatic white.

Band gap tailoring and enhanced ferromagnetism in Yb doped SrWo4 scheelite structured system

Room temperature ferromagnetism and enhanced optical property of Yb doped SrWO4 compounds have been investigated for the importance in the field of spintronics. Pristine and Yb doped SrWO4 compounds were synthesized by simple chemical precipitation method. Powder X-ray diffraction analysis reveals the scheelite type tetragonal structure of all the prepared compounds. The crystallite size and lattice strain was calculated by Williamson–Hall plot. The local structural disorder of the compounds was investigated by Laser Raman spectroscopy and it was found that the local disorder induced by the dopant leads to alteration in Raman active modes of Yb doped SrWO4 compounds. The formation of microsphere and platelets like shapes of particulate system was examined by electron microscopy techniques. The evidences for oxygen vacancy and oxidation states of elements present in the compounds were analyzed by X-ray photoemission spectroscopy. In UV–Vis spectra, distinctive shift of absorption edge was observed exclusively for all the Yb doped SrWO4 compounds. The presence of defective states with prominent blue and green emission of the compounds was investigated by photoluminescence spectroscopy. Magnetization study reveals that the pristine SrWO4 compound exhibits unsaturated ferromagnetic behaviour, whereas all the Yb doped SrWO4 compounds demonstrates saturated ferromagnetic behaviour. The enhancement of magnetization and ferromagnetic ordering of the compounds has been explained in terms of carrier-induced Ruderman–Kittel–Kasuya–Yosida interaction theory. Hence, from the present investigation it was observed that the doping of Yb in SrWO4 will yields a new kind of multifunctional material for fabricating magneto-optical and electronic devices.

Peanut shaped ZnO microstructures: controlled synthesis and nucleation growth toward low-cost dye sensitized solar cells

This paper describes a simple, low-temperature and cost effective chemical precipitation method in aqueous media to synthesis uniformly distributed zinc oxide (ZnO) microstructures for the fabrication of dye-sensitized solar cells (DSSCs). The size and morphology of the ZnO microstructures are systematically controlled by adjusting the concentration of the precursors, zinc acetate dihydrate and ammonium hydroxide. X-ray diffraction (XRD) and scanning electron microscopy are used for the structural characterizations and photoluminescence and Fourier transform infrared spectroscopy are used to characterize the optical properties of the ZnO, respectively. The results reveal that ZnO crystallites exhibit hexagonal wurtzite structure with preferential orientation along c-axis. The effect of ammonia concentration on the crystallinity, morphology and optical properties of ZnO microstructures and the concomitant effect on the efficiency of DSSCs is also quantified. The peanut-shaped ZnO microstructure, which was found to increase DSSCs performance over other microstructure, is studied in detail in order to develop a formation mechanism. A sandwich type eosin yellow sensitized solar cell is prepared using peanut-shaped ZnO microstructures, which showed an efficiency of 0.37%. Ammonia was found to play a crucial role in the evolution of ZnO morphologies. These results are promising and provide a path towards low-cost high-performance DSSCs based on peanut-shaped ZnO microstructures and produced with only relatively simple wet chemistry synthesis.

Enhancement in electrochemical behavior of copper doped MnO2 electrode

In the present work, we report a simple chemical precipitation method for the preparation of different levels of Cu doped MnO2 nanocrystals. X-ray diffraction, field emission transmission electron microscope and X-ray photoelectron spectroscopy were used to study the material properties. To demonstrate the suitability of the doped products for electrode applications electrochemical properties were evaluated by Cyclic Voltammetry (CV), galvanostatic charge–discharge studies and impedance spectroscopy. The results indicate that the MnO2 electrode modified with 0.1M of Cu has a better electrode property with a specific capacitance of 583F/g and an energy density of 80Whkg−1.

Polyethylene glycol ratio effect on magnesium oxide prepared by chemical precipitation: Impact on structure, morphology, and electrical properties

In this work, we investigate the properties of magnesium oxide powders synthesized via simple chemical precipitation (SPC). The effect of polyethylene glycol PEG (300) ratio in electrical behavior of MgO is the main part of this study. Crystalline structure and particle size were investigated through X-ray diffraction (XRD). Crystallite size of obtained MgO powders was calculated using Scherer׳s formula. Fourier transforms infrared spectroscopy (FTIR), Differential Thermal Analysis (DTA) and Gravimetric Analysis (TGA) were used to investigate PEG (300) effect. In fact the mass loss decreases when the PEG (300) ratio increases. Two type of OH group in the MgO surface sites: Type A and Type B with different coordinations, one for the first type and more (2, 3, 4) for the second, were highlighted. The number of OH group decreases when the ratio of MgO/PEG (300) increases. Ratio effect, on dielectric phenomena and electrical conductivity properties of MgO powders, was studied to improve the conductivity. XRD revealed that obtained MgO powders are crystalline and of high purity. Complex impedance spectroscopy was used to examine electrical properties. The activation energies of the MgO powders in the temperature range of study were correlated with PEG (300) ratio.

Structural and optical behavior of hexa-propyl methyl cellulose (HPMC) capped ZnS core–shell quantum dots

HPMC capped ZnS core–shell quantum dots were synthesized by using simple and eco friendly chemical precipitation method in which HPMC acts as a surface passivator as well as a functionalization agent to tune the properties. Morphological and optical characterizations were done to see the effect of HPMC capping on ZnS quantum dots. Morphological studies was done by using XRD and TEM. XRD studies confirms the pure zinc blende phase for all the samples. TEM studies shows that HPMC is efficiently controlling the agglomeration. Optical studies were done by using UV–visible and FTIR. UV–visible studies shows that bandgap is tunable on both sides of the wavelength depending on the concentration of HPMC. FTIR studies confirms the coating of HPMC on the surface of ZnS quantum dots. Laser induced time resolved photoluminescence studies were also done to see the effect of HPMC on the intensity of excited state life time of quantum dots. It is observed that the structural and optical characteristics have strong dependence on capping concentration. As HPMC is a very important viscoelastic polymer and organic surfactant used in various types of cosmetic binding applications and drug formulations, these studies opens a new way in the area of novel cosmetic design, efficient drug delivery and targeting and also specific optoelectronic applications using chalcogenide quantum dots.

Influence of Co and Dy Doping on the Optical and Magnetic Properties of ZnO Nanoparticles for DMS Application

Dysprosium-(Dy) and cobalt (Co)-doped zinc oxide (ZnO) nanoparticles with various concentrations have been synthesized by simple chemical precipitation method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDAX) measurements were conducted respectively for the structural, morphological, and compositional investigation of the sample. XRD analysis indicated that diffraction peaks of all the samples can be indexed to the hexagonal wurtzite structure of ZnO. No secondary phases including Co and Dy ions were detected in the samples even for the highest doping concentrations of Dy. Average particle size is found to be 25–34 nm. Scanning electron microscope and transmission electron microscope analysis revealed that the dopant atoms of Co and Dy are homogeneously distributed in ZnO wurtzite structure. The samples were characterized by EDAX to confirm the expected stoichiometry. In the photoluminescence spectra, Dy co-doped samples show a violet emission along with a broad yellow emission due to the4F9/2–6H15/2 inner shell transitions of Dy3+ ion. The photoluminescence (PL) enhancement process in Dy co-doped ZnO:Co is mainly due to Dy as a sensibilizer which could effectively enhance the luminescence intensity. Absorption spectra of dysprosium- (Dy) and cobalt (Co)-doped ZnO nanoparticles exhibited enhanced optical absorption in visible region. Magnetization measurements have shown that the particles have room temperature ferromagnetic behavior with relatively high coercive fields which are decreasing with the increase of doping concentration. The analysis of optical and magnetic properties shows that Co- and Dy-doped ZnO nanoparticles are a promising material for DMS application and have potential applications in optoelectronic devices.

Synthesis of 5-Fluorouracil conjugated LaF3:Tb3+/PEG-COOH nanoparticles and its studies on the interaction with bovine serum albumin: spectroscopic approach

The luminescent lanthanide-doped nanoparticles have gathered considerable attention in many fields especially in biomedicine. In this work, the lanthanum fluoride-doped terbium nanoparticles (LaF3:Tb3+ NPs) via simple chemical precipitation method has been synthesized and functionalized with polyethylene glycol. The size and the shape of the nanoparticles are confirmed using X-ray diffraction and transmission electron microscopy. The conjugation of 5-Fluorouracil (5-FU) and thus synthesized nanoparticles (NPs) were confirmed using various spectroscopic methods such as UV–Visible spectroscopy, fluorescence steady state, and excited state spectroscopy studies. The enhancement in fluorescence emission (λ = 543 nm) of drug-conjugated nanoparticles confirms the Vander Waals force of attraction due to F–F bonding between the drug and the nanoparticles. Further, the effects of 5FU-NPs in carrier protein were investigated using bovine serum albumin as a protein model. The 5FU–LaF3:Tb3+ nanoparticles binding is illustrated with binding constant and number of binding sites. The structural change of bovine serum albumin has been studied using circular dichroism and Fourier transform infrared spectroscopy analysis.

Synthesis of Mn3O4 nanoparticles via chemical precipitation approach for supercapacitor application

A simple chemical precipitation method has been used for the preparation of Mn3O4 nanoparticles at room temperature. The crystal structure and morphology studies of the resulting Mn3O4 nanoparticles were characterized by powder X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption and desorption and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of the Mn3O4 nanoparticles were then investigated using cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS) analysis. The supercapacitive properties of Mn3O4 nanoparticles in the presence of 1M Na2SO4 exhibited a high specific capacitance of 322Fg−1 at a current density of 0.5mAcm−2 in the potential range from −0.1 to +0.9V and about 77% of the initial capacitance was retained after 1000 cycles, indicating that the Mn3O4 electrode owns a good electrochemical stability and capacitance retention capability. The results suggest that the obtained Mn3O4 nanoparticles is a promising electrode material for supercapacitor applications.