Size Of CdS Nanoparticles Research Articles

Highly efficient photocatalyst fabricated from the recycling of heavy metal ions in wastewater for dye degradation

Water pollution and energy crisis are becoming global and strategic issues that people are closely concerned about. Green and energy-saving photocatalytic technology is developing rapidly in solving global energy crises and environmental pollution problems. Therefore, we propose the “kill two birds with one stone” strategy to design efficient photocatalysts for dye wastewater treatment by utilizing heavy metal ions in wastewater. The adsorption properties of Mordenite (MOR) were utilized to removal heavy metal ions (Cd2+ and Zn2+) from waste water, and the adsorbed heavy metal ions were dried and sulfurized to obtain CdS/ZnS/MOR(ZnCdM). Then, g-C3N4 was ultrasonically dispersed and composited with ZnCdM by self-assembly, 25 wt% ZnCdCM photocatalytic material was obtained with a degradation rate of 99.8% in 1.5 h for Rhodamine B(RhB). It was found that MOR can provid adequate support for active substances, and the surface of MOR with smaller sizes of CdS nanoparticles, ZnS nanoparticles and g-C3N4 nanosheets, which increased the specific surface area of the materials and improved the reactivity. The porous structure of MOR is favorable for the enrichment of RhB, and the electric field effect of MOR leads to the decrease of the photogenerated carrier complex rate in the semiconductor, which increases the catalytic efficiency. In addition, the double Z charge transfer mechanism formed by CdS, ZnS, g-C3N4 is favorable for separating photogenerated carriers. These synergistic effects improved the photocatalytic efficiency. This strategy will be a green and promising solution to water pollution and energy crisis.

The H-D-isotope effect of heavy water affecting ligand-mediated nanoparticle formation in SANS and NMR experiments.

An isotopic effect of normal (H2O) vs. heavy water (D2O) is well known to fundamentally affect the structure and chemical properties of proteins, for instance. Here, we correlate the results from small angle X-ray and neutron scattering (SAXS, SANS) with high-resolution scanning transmission electron microscopy to track the evolution of CdS nanoparticle size and crystallinity from aqueous solution in the presence of the organic ligand ethylenediaminetetraacetate (EDTA) at room temperature in both H2O and D2O. We provide evidence via SANS experiments that exchanging H2O with D2O impacts nanoparticle formation by changing the equilibria and dynamics of EDTA clusters in solution as investigated by nuclear magnetic resonance analysis. The colloidal stability of the CdS nanoparticles, covered by a layer of [Cd(EDTA)]2- complexes, is significantly reduced in D2O despite the strong stabilizing effect of EDTA in suspensions of normal water. Hence, conclusions about nanoparticle formation mechanisms from D2O solutions reveal limited transferability to reactions in normal water due to isotopic effects, which thus need to be discussed for contrast match experiments.

Structural and electrical properties of CdS nanocomposite solid films for electrolyte applications

ABSTRACT Solid Polymer electrolyte-based energy devices are playing a vital role for future energy sources. Solid state Poly (ethylene Oxide) polymer electrolyte was prepared by incorporating CdS nanoparticles. The precursor Cd(NO3)2 was incorporated in the host polymer to form a film and H2S gas was exposed on the film to convert it into CdS. The host polymer itself acted as a capping agent to reduce the size of CdS nanoparticles. The size distribution of CdS particles inside the matrix and the surface property were studied using Transmission Electron Microscope (TEM) and Atomic force microscope (AFM). The functional group present in the composites had been analyzed using Fourier Transform spectroscopy (FTIR). The electrical characteristics of the polymer nano composite electrolyte were characterized using impedance analyzer. The increase in ionic conductivity by varying the ratio of CdS:PEO was observed from the electrical studies.

Optica characterization of PVA/CdS nanostructure

CdS nanostructure has been synthesized of varied sizes in polyvinyl alcohol. The characterization of transmission electron microscopy (TEM) and X-ray diffraction (XRD) indicates the well dispersed CdS uniform sphere nanoparticles. The infrared spectral data confirmed that it has coordinated site to aggregate the Cd ions and different uniform sizes of CdS nanoparticles. The blue shift and optical band gap as a function of the particle sizes were studied form the UV-Visible spectra. Dielectric properties were studied in the frequency range from (2.5-5 MHz) as a function of temperature and the effect of particle sizes on the relaxation time were discussed.

The optical absorption and luminescent emission properties of Cd1-xHfxS QD nanocrystals prepared via 4,4’,N,N’-diphenylcarbazole assisted hydrothermal approach for QLED application potential

The semiconducting quantum dots based light emitting diode, QLED, have gained paramount interest from the scientific and technological point of views owing to their unique optical and photon management characteristics compared to the organic light emitting diode, OLED. Therefore, we report the syntheses of new semiconductor quantum dots based on Cd1-xHfxS nanocrystals. These nanocrystals QDs were prepared via 4,4’,N,N’-diphenylcarbazole assisted hydrothermal approach for QLED application potential. The TEM measurements inspected the opportunity of Hf-dopant tuning the size of CdS nanoparticles. The XRD inspected that the Hf-dopant caused an expansion of the CdS cubic crystals without alter its crystal phase. The optical absorption spectra disclosed that the HF-dopant caused red shift to the absorbance spectra and reduced the optical bandgap of CdS. The emission spectra declared that the HF-dopant enhanced the emission intensity of the CdS by 12 times and reduced the spectral width. The quantum yield of the CdS was improved from 17 % to 83 %, because the Hf-dopant behaved like activator fluorescent centers and acting as collector level for the photo-induced electrons of the Cds when subjected to light photons. The outstanding optical performance of the Cd1-xHfxS QD nanocrystals force them to be used for QLED applications.

Dielectric Measurements of Polymer Composite Based on CdS Quantum Dots in Low Density Polyethylene at Microwave Frequencies

CdS nanoparticles (NPs) as quantum dots (QDs) added into low density polyethylene (LDPE) can significantly change the MW dielectric properties of the composites. Introducing into the matrix of low density polyethylene CdS QDs increase the dielectric constant of more than twice. CdS QDs with concentration of 5 wt % to 20 wt % were prepared by the method of high-speed thermal decomposition. The size of CdS nanoparticles ranged from 2 nm to 7 nm. Experimental samples based on polymer-based nanocomposite in the form of thick films with a thickness of 80 to 100 microns were prepared by thermocompression. Complex dielectric permittivity of thick film samples was measured by T/R method from 2 to 8 GHz at room temperature (25°C). For samples with 20 wt % CdS NPs size effect was found. The change of dielectric properties of polymer composite materials is associated with the size of QDs. The dielectric constant and dielectric loss increases with decreasing size of the quantum dots. It is shown that the highest mean value of the dielectric constant and dielectric loss at a frequency range of 5 GHz to 8 GHz for cadmium sulfide nanoparticles with size of 4 nm were 12 and 189 dB/m, respectively. For QDs with ones of 6 nm average dielectric constant and dielectric loss were 5.8 and 134 dB/m, respectively. The effective dielectric constant and dielectric losses in the microwave range can be changed by CdS QDs of different sizes what consequently increases the possibility of using polymer nanocomposites as core elements of the microwave band-pass filters for various purposes.

Synthesis of Zn2TiO4@CdS Core‐shell Heteronanostructures by Novel Thermal Decomposition Approach for Photocatalytic Application

AbstractZn2TiO4@CdS core‐shell heteronanostructures with Zn2TiO4 as core and CdS nanoparticles as shell have been synthesized for the first time by a novel thermal decomposition approach. The size of CdS nanoparticles in the shell can be easily tuned by varying the amount of single molecular precursor (bis(thiourea)cadmium acetate, [Cd(CS(NH2)2)2]⋅(CH3COO)2). Various state‐of‐art analytical techniques prove the formation of Zn2TiO4@CdS core‐shell heteronanostructures. Powder XRD results confirm the presence of cubic Zn2TiO4 and hexagonal CdS in the core‐shell heteronanostructures. SEM and TEM studies indicate spherical morphology for pure Zn2TiO4 and formation of core‐shell structure in Zn2TiO4@CdS with Zn2TiO4 as core and CdS nanoparticles as shell. XPS measurements prove the presence of Zn2+, Ti4+, Cd2+ and S2− in the Zn2TiO4@CdS core‐shell heteronanostructures. The synthesized Zn2TiO4@CdS core‐shell heteronanostructures were explored for photocatalytic degradation of crystal violet in an aqueous solution. The core‐shell heteronanostructures exhibit better photocatalytic activity as compared to their parent materials.

In-situ synthesis of CdS@TiO2 Nanoparticles-nanobelt Heterojunctions with high photocatalytic property

In this study, CdS nanoparticles were in-situ deposited on the surface of TiO2 nanorods through the liquid phase synthesis method, and the CdS@TiO2 Nanoparticles-nanobelt heterojunctions were obtained. The nanobelts are 50-200nm in width and several tens of micrometers in length, while the size of CdS nanoparticles is about 10 nm. The photocatalytic properties of the products were also studied and the results showed that the photocatalytic activity of CdS@ TiO2 heterostructure is improved greatly compared with that of the common nanobelts. This is attributed to the different band energy structure of the two semiconductors, facilitating efficient charge separation and migration.

Comparative study on photocatalytic degradation of Congo red using different clay mineral/CdS nanocomposites

Clay mineral/CdS nanocomposites were successfully prepared via hydrothermal technique in the presence of different clay minerals for photocatalytic degradation of Congo red. The relevant structures and properties were systematically characterized and studied, including phase composition, crystal size, color, optical property and morphology of the obtained nanocomposites. The generated hexagonal CdS nanoparticles with a diameter of 30–60 nm were well anchored on the surface of clay minerals. Interestingly, the types of clay minerals affected the UV–Vis absorbance and band-gap energy of clay mineral/CdS nanocomposites, and the clay mineral/CdS nanocomposites derived from one-dimensional halloysite, sepiolite, and palygorskite exhibited higher photocatalytic activity for Congo red degradation than that of two-dimensional lamellar kaolin and montmorillonite. In addition, incorporating of clay minerals not only effectively decreased the size of CdS nanoparticles without the obvious aggregation, but also guard against electrochemical corrosion of CdS during photocatalytic degradation.

Synthesis of 3D mesoporous alumina from natural clays for confining CdS nanoparticles and enhanced photocatalytic performances

Abstract A spatial confinement effect of CdS nanoparticles in mesoporous alumina, which is synthesized through evaporation-induced self-assembly (EISA) method, post-impregnation approach and microwave irradiation process, was investigated to verify the enhanced catalytic activity and stability with less aggregation of CdS crystallites during decoloration of organic dyes under visible-light irradiation. In this work, we utilize inexpensive natural clays for preparing mesoporous alumina via evaporation-induced self-assembly method, and used as the host for confining CdS nanoparticles to suppress the crystallite growth and aggregation. The loading amount and grain size of CdS nanoparticles significantly altered catalytic activity and stability. CdS clusters confined inside the mesoporous channels provided abundant reactive sites for photocatalytic reaction through spatial confinement effect, quantum size effect and sulfide-support interaction, thus greatly enhancing the reaction activity. CdS/MAl composites have large special surface area, strong visible light absorption and high quantum yields. CdS/MAl-25 photocatalyst has exhibited remarkably enhanced visible light photoactivities as compared to other catalysts, and the overall decoloration rate was up to 97.5% after visible light irradiation for 60 min. The CdS/MAl composites exhibit potential applications in the wastewater treatment under visible light irradiation.

Tuning of optical properties of CdS nanoparticles synthesized in a glass matrix

Attempts were made to provide the data concerning directed synthesis of semiconductor nanoparticles in a dielectric silica-based glass matrix. These attempts involve finding out the connections between the structure, size of CdS nanoparticles, and optical properties of the nanocomposites produced. High-resolution focused ion beam scanning electron microscopy images of CdS nanoparticles incorporated in glass and SAXS results confirm the formation of uniformly distributed spherical CdS nanoparticles with an average diameter of about 6.2 nm. UV–Vis measurements show that CdS composites possess a direct bandgap wider than 2.45 eV depending on the heat treatment conditions; thus, heat treatment can be used to control nanoparticle size in each selected composite. The emission spectra showed a maximum at about 603 nm and a red shift of about 100 nm with increasing annealing temperature that is associated with the presence of defect states in the nanoparticles. In addition, semiconductor phase concentration in the glass matrix was found by using optical absorption data for the first time, which allows understanding the effect of nanocomposite structure on luminescence properties.

Enhanced green and orange photoluminescence of nanostructured CdS in glass nanocomposites by energy transfer From Ho3+ and Eu3+ ions

We report enhanced photoluminescence (PL) of both band edge and trap state emissions in Ho3+ or Eu3+ ion doped CdS (II-VI semiconductor) nanoparticles (NPs) containing glass nanocomposites. These glass nanocomposites were synthesized by the conventional melt-quench technique. The sizes of CdS NPs are found to increase from 5–15 nm to 40–80 nm with the increase in thermal treatment. Band edge emission (green emission, peak around 495 nm) of CdS NPs is controlled by their size and enhanced about three to nine-fold by Ho3+ ions on excitation at 446 nm by a diode laser. Under the same excitation, twelve to fifty-fold enhanced trap state emission (orange and red emissions about 550–900 nm) of CdS NPs is obtained by Eu3+-doping compared to undoped CdS NPs containing glass nanocomposites. The predominant mechanism of PL enhancement is the energy transfer from rare earth ions to CdS NPs. Enhanced PL of these nanocomposites enables their applications in efficient solar concentrators, green and red light emitting component for white light emission devices.

Enhanced magnetoconductivity and electrical property of MWCNT-CdS nanocomposite embedded in polyaniline

PANI/MWCNT-CdS nanocomposites with different content of CdS wt.% has been synthesized by the chemical oxidative in-situ polymerization reaction of aniline in the presence of multi-walled carbon nanotubes (MWCNT). TEM, XRD, FTIR, and TGA studies were done for the structural and thermal characterization of the samples respectively. The particle size of CdS nanoparticles distributes in between 2.7 and 4.8 nm. XRD spectrum reveals that the co-existence of MWCNT, CdS in PANI matrix, where CdS forms a hexagonal structure. TGA result shows that nanocomposite becomes more thermally stable with the increase in CdS content. The dc electrical transport property of PANI/MWCNT-CdS nanocomposites has been investigated within a temperature range 77 ≤ T ≤ 300 K. The dc conductivity follows a 3D variable range hopping (VRH) model. A large magnetoconductivity change (19%) is observed for 2 wt% CdS content in PANI/MWCNT-CdS, which is explained by the wave function shrinkage model.

Structural Features of Nanocomposites Based on Cadmium Sulfide Nanoparticles in Glass Matrix

We study stable stable transparent monolithic nanocomposites based on the silica matrix doped with CdS nanoparticles (NPs) of different nature. The first kind of nanocomposite was obtained by nucleation and growth of nanoparticles in glass matrix during heat treatment. The second nanocomposite was obtained by immobilization of pre-made nanoparticles into silica gel matrix. This work is focused on characterization of the nanocomposites in the submicron scale by using electron microscopy and small angle x-ray scattering techniques. Experimental results show that both types of nanocomposites have homogeneous distribution of quantum dots. Form-factor and average size of CdS NPs depend on the synthesis technique

Reduced graphene–cadmium sulfide hybrid nanopowders: solvothermal synthesis and enhanced electrochemical performance

Graphene–cadmium sulfide nanocomposite (G–CdS) was prepared by one pot solvothermal route. Graphite oxide (GO) was well dispersed in dimethyl sulfoxide (DMSO) solution of ions Cd2+, where DMSO acted as a sulphide source as well as reducing agent, resulting in the formation of G–CdS nanocomposite and simultaneous reduction of GO to graphene nanosheets (GNs). The size of CdS nanoparticles (NPs) in G–CdS was around 10 nm, and the large 2D flexible atom-thin layer of graphene made it easier to control the distribution of CdS NPs. The electrochemical performances of G–CdS nanocomposite were investigated by cyclic voltammetry and charge/discharge techniques. It showed that the G–CdS nanocomposite had a high electrochemical activity, durability, and stability. And the electronic conductivity of nanocomposite was improved and the stability of electrode was enhanced because of the introduction of GNs.

Ferromagnetic behaviour at room temperature of Co doped CdS nanoparticles by chemical precipitation method: Synthesis, optical and electrical properties

Cobalt doped CdS nanoparticles were prepared by chemical precipitation method. The prepared powder were characterized by various analytical techniques such as Powder XRD, SEM, EDAX, Magnetic and spectroscopic analysis of nanoparticles as a function of cobalt concentration have been systematically studied.The XRD study confirms the high crystalline nature of prepared compounds and the presence of hexagonal phase of the CdS nanoparticles. The particle size of CdS nanoparticles are calculated by Scherer's formula and it is found that the particles are in the range of 8 to 10 nm.

Effect of the Nature of Cadmium Salts on the Effectiveness of CdS SILAR Deposition and Its Consequences on the Performance of Sensitized Solar Cells

Nanocrystalline titania films deposited on FTO transparent electrodes were sensitized by CdS nanoparticles synthesized in situ by the SILAR method. Three precursor solutions were employed for adsorption of Cd2+ ions: nitrate, sulfate, and acetate. The CdS load and the size of CdS nanoparticles varied a lot from one precursor to the other. The highest load and the largest nanoparticles were obtained in the case of cadmium acetate, the smallest in the case of nitrate, while sulfate gave intermediate values. Ultraviolet photoelectron spectroscopy was employed to measure the ionization potential (and valence band potential) for pure titania and for sensitized titania in the three cases. The obtained values were 7.4 eV for pure titania and 6.7, 6.6, and 5.7 eV for CdS-sensitized titania made by using cadmium nitrate, sulfate, and acetate precursors, respectively. The corresponding band gap values ranged between 2.5 and 2.3 eV. The thus characterized photoanodes were employed to make Quantum Dot Sensitized Sola...

Structure and optical properties of capped and uncapped CdS nanoparticles prepared in aqueous medium

We have prepared the hexagonal structure of CdS nanoparticles in an aqueous solution with different sizes and varied surface compositions by using fixed molar ratio of the starting precursors in the presence of capping molecules. In addition, we have prepared uncapped CdS nanoparticles by cadmium chloride and thiourea at low temperature. We showed that the environmental conditions and the type of the aqueous medium are the effective parameters for the exchange of the nanoparticle size. The prepared nanoparticles have sizes in the range from 25 to 100 A. We have compared the experimentally determined size of CdS nanoparticles with that determined by theoretical calculations. The comparison showed that the size determined by Scherrer’s equation is fitted well with the empirical tight binding calculations, and that the effective mass approximation yields size values is in good agreement with the size estimated by high resolution transmission electron microscopy. Photoluminescence spectroscopy revealed that the nanoparticles with stoichiometries composition S/Cd ~ 1 have a high intensity band edge emission in the blue region for the capped nanoparticles and green emission for the uncapped nanoparticles.

Photoluminescence of CdS nanoparticles grown on carbon nanotubes covered by a dielectric polymer layer

Photoluminescence (PL) properties of CdS nanoparticles were studied depending on spacing between the nanoparticles and carbon nanotube (CNT) surface. Using a chemical bath deposition procedure the nanoparticles were grown directly on CNT arrays or arrays covered by a polystyrene layer. The polymer thickness was changed by varying the polystyrene concentration in a solution and the duration of CNT immersing. Transmission electron microscopy and atomic force microscopy were used for estimation of CdS nanoparticle size. An increase in the separation between CdS and CNTs was found to enhance the PL intensity and contribute to the exciton lifetime. PL spectra of CdS nanoparticles grown on a CNT surface and polystyrene layer coating the CNTs.

Biosynthesis of semiconductor nanoparticles by using sulfur reducing bacteria Serratia nematodiphila

The synthesis of semiconductor nanoparticles is a growing research area due to the prospective applications for the development of novel technologies. In this paper we have reported the biosynthesis of Cadmium sulfide nanoparticles (CdSNPs) by reduction of cadmium sulphate solution, using the bacteria of Serratia nematodiphila. The process for the synthesis of CdS nanoparticles is fast, novel and ecofriently. Formation of the CdS nanoparticles was confirmed by surface Plasmon spectra using UV-Vis spectrophotometer and absorbance strong peak at 420 nm. The morphology of crystalline phase of nanoparticles was determined from Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy and X-ray diffraction (XRD) spectra. The average size of CdS nanoparticles was in the range of 12 nm and the observed morphology was spherical. The results indicated that the proteins, which contain amine groups, played a reducing and controlling responsibility during the formation of CdS nanoparticles in the colloidal solution. Antibacterial activity against some bacteria such as Bacillus subtilis, Klebsiella planticola. CdS nanoparticles exhibiting good bactericidal activity.