Visible Light-Induced Degradation of Methylene Blue in the Presence of Photocatalytic ZnS and CdS Nanoparticles

ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight) was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles after 6 h irradiation time was about 73% with a reaction rate of 3.61 × 10⁻³ min⁻¹. Higher degradation efficiency and reaction rate were achieved by increasing the amount of photocatalyst and initial pH of the solution.     

Evaluation of diffusion mechanism and structural characterizations of ZnS compound during chemical reaction of Zn and S in liquid phase

The present study investigates the diffusion mechanism, morphology and structural characteristics of crystalline zinc sulfide (ZnS) during the reactive diffusion process. The samples with nominal composition of Zn₅₀S₅₀ were prepared via capsulation of high purity of zinc and sulfur followed by the annealing process at various reaction temperatures. The prepared samples were characterized using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. The structural measurements confirm the formation of zinc sulfide with wurtzite structure during the annealing process at 550°C. The wurtzite allotrope of ZnS is not stable at a high annealing temperature and is transformed to cubic zinc-blende structure. During the annealing process, a continuous layer of ZnS compound forms at the Zn/S interface. Both Zn and S diffuse into the formed ZnS layer and the growth of that occurs mainly toward the Zn side. Under this condition, Kirkendall voids form and accumulate near the ZnS/S interface.     

Synthesis of CdS‐ and ZnS‐modified bentonite nanoparticles and their applications to the degradation of eosin B

BACKGROUND: In the present study, nanocomposites of cadmium sulphide (CdS) and zinc sulphide (ZnS) on a bentonite have been prepared via an in‐situ precipitation route and their catalytic behaviour was evaluated in the degradation of eosin B. RESULTS: It was found that the basal space of bentonite increased from 1.23 to 1.49 nm after CdS or ZnS nanoparticles were deposited on layers of the bentonite. The resulting CdS–bentonite and ZnS–bentonite nanocomposites can degrade eosin B from aqueous solution after 2 h under UV irradiation. CONCLUSION: A soft method for in situ synthesis of monodispersed, CdS and ZnS nanoparticles, using a reverse micelle type procedure, is reported. The synthesized CdS‐ and ZnS–bentonite composites combined the adsorptive ability of bentonite and the catalytic degradation ability of CdS and ZnS to remove eosin B from its aqueous solution efficiently. Copyright © 2009 Society of Chemical Industry     

Controlled growth of CdS nanoparticles in polyurushiol matrices

A method for fabrication of urushiol–cadmium coordination polymer was developed under UV irradiation, and then hybrid composites of CdS nanoparticles embedded in polyurushiol (PU) matrices were prepared by immersion the coordination polymer in thioacetamide (TAA). XPS measurements showed the coordination between cadmium ion and oxygen after UV irradiation. In the course of UV irradiation, the hydroxyl groups on the phenyl ring of urushiol were dissociated to urushiol semiquinone, and coordinated with cadmium ions to form complexes. The –OH groups on the phenyl ring of urushiol acted as the coordination sites for cadmium ion aggregations and the nanosized CdS particles were successfully grown in situ at these sites with the release of S²⁻ ions from TAA. The results from X-ray powder diffraction (XRD) analysis and the FT-IR spectra showed the formation of CdS nanoparticles and the polymerization of urushiol monomers. TEM showed that CdS nanoparticles were homogeneously dispersed in PU matrices. TG analysis showed that the PU/CdS nanocomposites had excellent thermo-stability. A possible formation mechanism of CdS nanoparticles in the PU matrices was also suggested based on the experimental results.     

Synthesis,structural and optical properties of ZnS,CdS and HgS nanoparticles from dithiocarbamato single molecule precursors

Dithiocarbamate complexes of Zn(II), Cd(II) and Hg(II) were synthesize and characterized by elemental analysis, thermogravimetric analysis, UV–Vis, FTIR, ¹H- and ¹³C-NMR spectroscopy. The complexes were thermolyzed at 180°C to prepare HDA-capped ZnS, CdS and HgS nanoparticles. The optical properties of the nanoparticles showed absorptions that are blue shifted with respect to the bulk and narrow emissions. The ZnS nanoparticles are in the cubic phase with average crystallite sizes of 3–5 nm. The CdS nanoparticles consist of a mixture of cubic and hexagonal phases with particle sizes of 8–22 nm, while the HgS nanoparticles are in the cubic phase with average crystallite sizes of 7–14 nm.     

Study of Crystallization and Spectral Properties of Zinc Sulfide Nanoparticles in Mesoporous Matrix

The aim of this work is to report the optical and structural properties of ZnS nanoparticles in mesoporous matrix. The samples were obtained by sulfidation of the Zn²⁺ ion-exchange mesopore in a Na₂S solution at room temperature. The final product (ZnS/MCM-41) was characterized by X-ray diffraction (XRD) pattern, transmission electron microscopy, scanning electron microscopy (SEM), infrared spectrometry and UV–Vis spectroscopy. Its crystalline structure and morphology was studied by XRD and SEM. Exciton absorption peaks at higher energy than the fundamental absorption edge of bulk ZnS indicates quantum confinement effects in nanoparticles as a consequence of their small size.     

Enhanced optical properties of ZnS–rGO nanocomposites for ultraviolet detection applications

In this research, fabrication and characterization of ultraviolet (UV) detectors based on zinc sulfide–reduced graphene oxide (rGO) nanocomposite with the focus on the wurtzite structure of zinc sulfide was carried out. The nanoparticles of ZnS were synthesized using chemical deposition method and annealed at 500?°C under flow of argon. X-ray diffraction pattern showed that ZnS with the wurtzite phase was formed at 500?°C. Here, rGO as a unique material with similar properties to graphene such as high electron transport was used in order to improve the optical properties of ZnS. For this purpose, rGO was added to ZnS with three different weight percentages of 5, 10 and 15. Scanning electron microscopy showed that ZnS nanoparticles were well placed in rGO sheets. The UV–visible spectra of the synthesized composites showed that with increasing rGO in composite, light absorption is increased. Photoluminescence (PL) spectra also showed that with increasing the percentage of rGO the generation of electron-hole in composite was increased and PL peak was enhanced. The effect of elevated generation of electron-hole pairs was apparent in optoelectrical properties of fabricated UV detectors based on the sample with higher concentration of rGO in composite. For this sample, the response time was decreased to 310 ms, and the sensitivity to UV irradiation was increased by 7.7 times.     

ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors

The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively.     

Effect of Cationic Surfactant Head Groups on Synthesis, Growth and Agglomeration Behavior of ZnS Nanoparticles

Colloidal nanodispersions of ZnS have been prepared using aqueous micellar solution of two cationic surfactants of trimethylammonium/pyridinium series with different head groups i.e., cetyltrimethylammonium chloride (CTAC) and cetyltrimethylpyridinium chloride (CPyC). The role of these surfactants in controlling size, agglomeration behavior and photophysical properties of ZnS nanoparticles has been discussed. UV–visible spectroscopy has been carried out for determination of optical band gap and size of ZnS nanoparticles. Transmission electron microscopy and dynamic light scattering were used to measure sizes and size distribution of ZnS nanoparticles. Powder X-ray analysis (Powder XRD) reveals the cubic structure of nanocrystallite in powdered sample. The photoluminescence emission band exhibits red shift for ZnS nanoparticles in CTAC compared to those in CPyC. The aggregation behavior in two surfactants has been compared using turbidity measurements after redispersing the nanoparticles in water. In situ evolution and growth of ZnS nanoparticles in two different surfactants have been compared through time-dependent absorption behavior and UV irradiation studies. Electrical conductivity measurements reveal that CPyC micelles better stabilize the nanoparticles than that of CTAC.     

微乳液中纳米ZnS、CdS微粒的合成与表征

以乙酸锌、硝酸镉和硫化钠为原料,室温下,采用微乳液法合成ZnS、CdS纳米粒子。利用rIEM、XRD、Raman、UV-Vis和PL等检测手段对产物进行表征。结果表明,合成的zns纳米晶粒径在25m左右,为立方β-Zns晶相;ω值对合成纳米cds的形貌和粒径产生重要影响,纳米Cds粒径为5nm左右,在紫外吸收光谱和荧光发射光谱上均表现出明显的特征,可作为荧光量子点使用。     

Facile synthesis of CdS nanoparticles photocatalyst with high performance

A simple one-step solid-state reaction has been introduced to synthesize CdS nanoparticles. The as-prepared CdS product was characterized by X-ray powder diffraction (XRD), BET surface area measurement, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), particle size distribution (PSD) and UV–vis absorption spectrum. The experiment results reveal that the CdS product was composed of nanoparticles about 60 nm in diameter, of which specific surface area is 78.02 m²/g. The photocatalysis results indicate that the CdS nanoparticles exhibit excellent photocatalytic activity for the degradation of rhodamine B under UV irradiation. Nearly 95% of rhodamine B was degraded after 60 min of irradiation, higher than that of P25, which is due to the large specific surface area and mesoporous structure.     

Colloidal Synthesis of ZnS,CdS and Zn x Cd1−x S Nanoparticles from Zinc and Cadmium Thiobiuret Complexes

ZnS, CdS and Zn _x Cd_1?x S nanoparticles were synthesised from the thermolysis of 1,1,5,5-tetra-iso-propyl-4-thiobiuret complexes of Zn and/or Cd in oleylamine. The influence of the different reaction parameters (precursor concentration, growth temperature, reaction time and injection solvent/capping agent combination) on the size, morphology and optical properties of the produced nanoparticles were studied. ZnS nanoparticles with size smaller than 4.3 nm had the cubic phase whereas the particles with size larger than 4.3 nm had a hexagonal crystal structure as suggested by the selected area electron diffraction. Transmission electron microscopy showed the formation of spherical ZnS nanoparticles in addition to few ZnS nanorods only at growth temperature of 280 °C. Powder X-Ray diffraction (p-XRD) showed that the obtained CdS nanoparticles were cubic under all reaction conditions except when dodecanethiol was used as an injection solvent which produced hexagonal CdS. The change in the crystal structure of the CdS nanoparticles was accompanied with a change in morphology from spherical to triangular. Cubic Zn _x Cd_1?x S nanoparticles were obtained under all reaction conditions. Lattice spacing of the Zn _x Cd_1?x S nanoparticles showed a very good agreement with Vegard’s law. The optical properties of the Zn _x Cd_1?x S nanoparticles were highly dependent on the ZnS to CdS precursor ratio and the solvents/capping agent combinations. This in detail study on the relationship of solvent systems (capping agents), thermolysis temperatures, time of reactions and precursors will help in understanding to control the morphology, size of the crystallites and phase of the materials.     

Phase Controlled Monodispersed CdS Nanocrystals Synthesized in Polymer Solution Using Microwave Irradiation

Cadmium sulfide (CdS) nanocrystals were synthesized in aqueous solution of polyvinyl pyrrolidone (PVP) via the simple and rapid microwave irradiation method. It is revealed that sulfur source is a key factor in controlling the phase formation of the resulting nanocrystals. The hexagonal and cubic structure of CdS nanocrystals could be obtained with varying sulfur sources of thioacetamide and sodium sulphide respectively. The interaction mechanism of PVP with precursor ions of cadmium and sulfur sources in the preparation process was proposed. It is found that PVP compounded the CdS nanoparticles and protected them from agglomerating. With increasing of PVP concentration, the average particle size of CdS nanocrystals increased and subsequently their optical band gap decreased. At the appropriate dosage of PVP, well isolated nanoparticles with relatively narrow size distribution were obtained for both sulfur sources. Moreover the stability of CdS nanoparticles enhanced after coating with polymer.     

Investigation of multilayered quantum dot-sensitized solar cells with different Zn chalcogenide passivation layers

In the case of cadmium sulfide (CdS) and cadmium selenide (CdSe)-based quantum dot-sensitized solar cells (QDSSCs), the addition of a zinc sulfide (ZnS) passivation layer improves the solar cell performance. In this study, multilayered QDSSCs were fabricated using CdS and CdSe quantum dots prepared by successive ionic layer adsorption and reaction (SILAR) method. The optimized QDSSCs were used to study the passivation effect of zinc chalcogenide layers: ZnS, zinc selenide (ZnSe), and zinc telluride (ZnTe). The best performing solar cell prepared from four SILAR cycles of CdS followed by six SILAR cycles of CdSe were used for subsequent deposition of Zn chalcogenide layers. It was observed that capping with ZnSe or ZnTe layer on the multilayered Cd chalcogenide QDs did not improve the solar cell performance. Only the addition of ZnS layer contributed to the better performance of the solar cell. The efficiency obtained in the optimized multilayered CdS/CdSe QDSSC with ZnS layer was 1.37 %, while the QDSSC with ZnSe or ZnTe capping showed lower performance. The behavior of the solar cells is explained with electrochemical impedance spectroscopy study.     

TiO2/MS(M=Cd,Zn,Cu)纳米复合光催化剂的制备及光催化活性研究

在室温下,以正丁胺为模板剂[1],通过简单的化学方法合成ZnS,CdS,CuS纳米颗粒.以钛酸丁酯为主要原料,用溶胶-凝胶法制备了TiO2/ZnS,TiO2/CdS,TiO2/CuS的纳米复合物,采用UV-Vis对其进行简单表征.并通过测定甲基橙的脱色速率,评价所有样品的光催化活性.结果表明:不同的硫化物在同一复合量时...     

Synthesis and optical properties of glass with cadmium sulfide nanoparticles

A new approach to the synthesis of silicate glass with cadmium sulfide (CdS) nanoparticles has been developed. It has been demonstrated that replacement of cadmium sulfide with cadmium oxide and zinc sulfide used as sources of cadmium and sulfur allows a substantial reduction of sulfur volatilization during the melting. The produced samples have been investigated by the methods of spectrophotometry in the ultraviolet and visible ranges of the optical range. Thermal treatment of the samples at temperatures exceeding the glass formation point initiates the growth of CdS nanoparticles, which results in the increase of their average size from 3 to 5.2 nm and a significant shift of the fundamental absorption edge to the longer wavelength range from 380 to 480 nm.     

In situ preparation of CdS/PVA nanocomposites using gamma radiation

Films of poly(vinyl alcohol)/cadmium sulphide (PVA/CdS) nanocomposite containing various concentrations of Cd²⁺ ions were prepared using gamma radiation at different doses from 50 up to 200 kGy. The UV/VIS spectra revealed that the CdS/PVA nanocomposites showed blue shift for the absorption peak as compared with bulk CdS. As the irradiation dose increased, a gradual red shift in the wavelength accompanying with broadening of the absorption peak was observed. The estimated optical band gap energies and the calculated CdS particle sizes of (PVA/CdS) showed correlation between their values and the variable parameters (irradiation dose and Cd⁺²:S^?2 molar ratio). Transmission electron microscopy images showed that the CdS/PVA nanocomposites were dispersed as spherical CdS nanoparticles with homogeneity at either lower concentration of CdCl₂ or irradiation dose. The nano‐rod structures of CdS was accompanied with small agglomeration at either higher CdCl₂ concentration or irradiation dose. A cubic phase and mixture of cubic and hexagonal phases of the prepared CdS nanoparticles were formed at lower and higher CdCl₂ concentrations, respectively. Fourier Transform Infrared spectra confirmed the coordination of CdS nanoparticles with the hydroxyl groups of PVA matrix. POLYM. ENG. SCI., 55:2583–2590, 2015. © 2015 Society of Plastics Engineers     

Synthesis of CdS nanoparticles dispersed within solutions and polymer films using amphiphilic urethane acrylate chains

In this study, a new process for preparation of CdS/polymer nanocomposite films using a new amphiphilic oligomer chain (Urethane Acrylate Nonionomer: UAN) is presented. UAN chains have hydrophilic polyethylene oxide segments and polypropylene oxide-based hydrophobic segments as part of the same backbone. In addition, these chains also have reactive vinyl groups at their hydrophobic segments. For the preparation of CdS nano-colloid solutions, UAN chains acted as a stabilizer for CdS nanoparticles dispersed in a solvent. For the fabrication of CdS/polymer nanocomposite films, UAN chains in CdS nano-colloid solutions were polymerized through reactions between their vinyl groups, resulting in the formation of CdS nanoparticle dispersed films swollen by the solvent. The nature of the solvent used strongly influenced the size of the CdS nanoparticles, which was confirmed by UV absorption spectra, PL emission spectra and TEM images. Smaller sized CdS nanoparticles were formed in higher polar solvents such as DMAc and methanol, which can be explained by the higher solubility of UAN chains and the more effective dissociation and stabilization of cadmium salts and CdS nanoparticles by UAN chains in the polar solvent.     

Fabrication of polymer/ZnS nanoparticle composites by matrix-mediated synthesis

Zinc sulfide nanoparticles are obtained as primary particles in a polymer matrix by a matrix-mediated synthesis. Two types of matrix polymer are synthesized via the copolymerization of hydrophobic, cation-exchange, and cross-linking monomers. The ZnS nanoparticles are affected by the composition of the matrix polymer, and especially by its hydrophobicity. In a low-hydrophobicity copolymer matrix, aggregates of ZnS nanoparticles are observed in the matrix using transmission electron microscopy (TEM) and X-ray diffraction (XRD). In a high-hydrophobicity cation-exchange copolymer matrix, primary particles of ZnS with 2–5 nm diameters are observed in the matrix by TEM. However, the ZnS pattern is not distinguishable in XRD measurements because the particle sizes are too small to diffract X-rays.