Morphology Of CdS Research Articles

Preparation of self-assembled hollow microsphere CdS via solvothermal method and its optical properties

In this work, the hollow microsphere CdS has been prepared by solvothermal method with oxalic acid as auxiliary agent. The effects of different experimental conditions on the morphology of CdS have been investigated. The as-prepared CdS has been analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer, room temperature photoluminescence and ultraviolet–visible (UV–Vis). And the photocatalytic activity has been investigated on the degradation of methylene blue under simulated solar light irradiation. XRD result indicates that hollow microsphere CdS is hexagonal phase, which is highly crystallized. FE-SEM results indicate that the diameter of hollow microsphere CdS is about 5 μm, and the diameter of center hole is about 500 nm. UV–Vis result indicate that hollow microsphere CdS has a strong absorption in visible light region and the optical energy band gap is 2.31 eV. The fluorescence spectrum shows that hollow microsphere CdS structures have three emission peaks at 455, 545 and 582 nm, respectively. Photocatalytic result shows that the activity of hollow microsphere CdS remains 90 % after 5 recycle times, which indicates that hollow microsphere CdS has a good catalytic efficiency and stability to methylene blue. The growth mechanism of hollow microsphere CdS structures is also described.

Nucleation and growth of CBD-CdS thin films on ultrathin aluminium layers and annealing induced doping

Using chemical bath deposition CdS films were grown onto vacuum evaporated ultrathin aluminium films (25nm). The Al/CdS bilayers thus formed were subjected to heat treatment at the temperatures 300°C, 400°C for 4min and 500°C for 90s in a muffle furnace to facilitate aluminium to diffuse into the CdS films. XRD studies ascertained the shift of the lattice constant owing to introduction of Al into CdS crystal lattice by annealing CdS:Al at 400°C. Secondary ion mass spectrometry indicated almost uniform distribution of aluminium atoms throughout the bulk of CdS subject to annealing. SEM images showed the distinct changes in surface morphology of CdS, grown on aluminium surface, from that on bare glass substrate. CdS:Al films (annealed at 400°C) showed higher transmission in the visible range compared to pristine CdS.

Synthesis of Novel Sea-Urchin-Like CdS and Their Optical Properties.

A novel morphology of CdS sea-urchin-like microstructures is synthesized by simple thermal evaporation process. Microstructures with average size of 20-50 μm are composed of single crystalline CdS nanobelts. The structural, compositional, morphological characterization of the product were examined by X-ray diffraction, energy dispersive X-ray spectroscopy, Raman spectroscopy, scanning electron microscope, transmission electron microscopy and selected area electron diffraction while optical properties are investigated by Photoluminescence spectroscopy and time-resolved Photoluminescence measurements. The tentative growth mechanism for the growth of sea-urchin-like CdS is proposed and described briefly. A strong green emission with a maximum around 517 nm was observed from the individual CdS microstructure at room temperature, which was attributed to band-edge emission of CdS. These Novel structures exhibit excellent lasing (stimulated emission) with low threshold (9.07 μJ cm(-2)) at room temperature. We analyze the physical mechanism of stimulated emission. These results are important in the design of green luminescence, low-threshold laser and display devices in the future.

Preparation of dendritic‐like CdS by hydrothermal method and its photocatalytic performance

In this article, dendritic‐like CdS has been prepared by a hydrothermal method using thiourea as the sulfur source, and the effects of experimental conditions on the morphologies of CdS have been investigated. The performances of CdS have been analyzed by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and the fluorescence and photodegradation properties of CdS have also been investigated. The XRD result indicates that the dendritic‐like CdS are of hexagonal phase and they are highly crystallized. Also, the FESEM results show that the ratio of raw material affects the yield of CdS, the reaction time affects the morphology of CdS. The best morphology of CdS is dendritic structures and the length is about 6 μm. The fluorescence spectrum shows three peaks at 470 nm, 513 nm and 547 nm, which indicates that the dendritic‐like CdS mainly emits green and blue fluorescence. Moreover, the dendritic‐like CdS exhibits good photocatalytic activity and its photodegradation rate to methylene blue can reach 92%. The growth mechanism for the formation of CdS with dendritic structure is also described.

Atomistic Simulations of CdS Morphologies

Atomistic simulations based on the static lattice model are performed to calculate the equilibrium and growth morphologies of CdS polymorphs. Morphologically important surfaces are optimized to calculate their structural and energetical properties such as surface and attachment energies. A common feature of all the nonpolar CdS surfaces is the outward movement of their anions and the inward movement of their cations. The relaxation of surfaces is critically important as it changes the surface and attachment energies significantly. The {112̅0} surface has the lowest surface energy (0.58 J/m2) for the wurtzite phase of CdS, whereas {110} surface has the lowest surface energy (0.62 J/m2) for the zincblend phase of CdS. The {101̅0}, {123̅0}, and {11̅00} surfaces of wurtzite CdS all have the same surface energy value (0.60 J/m2), which is very close to that of {112̅0} surface. Therefore, all these surfaces appear in the equilibrium morphology of the wurtzite CdS. The equilibrium morphology of the zincblend CdS is completely dominated by the {110} surface. The growth morphology of the wurtzite CdS consists of {101̅0}, {11̅00}, {0001}, and {0001̅} surfaces. The growth morphology of the zincblend CdS is found to be identical to its equilibrium morphology and, therefore, includes only the {110} surface.

Preparation of flower-like CdS with SDBS as surfactant by hydrothermal method and its optical properties

In this article, the flower-like CdS have been prepared by hydrothermal method with thiourea as sulfur source and SDBS as surfactant. The effects of different experimental conditions on the morphology of CdS have been investigated. The performances of CdS have been analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), room temperature photoluminescence (PL) and UV–vis. The result of XRD indicates that CdS we prepared are highly crystallized, which are of hexagonal phase. The FE-SEM results indicate that the main role of SDBS is to make the CdS crystals assemble together to form the flower-like structures, and the reaction time affects the morphology of CdS, and the suitable reaction temperature is 160°C. Its optical energy band gap is observed at 2.50eV. The fluorescence spectrum shows that the flower-like CdS have a broad absorption peak and the max emission wavelength is 508.6nm. The growth mechanism for the formation of CdS with flower-like structures is also described.

Control of the crystalline phase and morphology of CdS deposited on microstructured surfaces by chemical bath deposition

Chemical bath deposition (CBD) has been used extensively to deposit thin films of CdS for window layers in solar cells. The microtopography or roughness of the surface, however, can affect the quality of the film by influencing the morphology, uniformity, or crystal phase of the CdS film. Here, we have demonstrated that thin films of CdS can be successfully patterned on surfaces bearing micropillars as a model surface for roughness. The phase purity of CdS deposited on the micropillar surfaces is uniform and conformal with the formation of packed clusters on the micropillars at pH 10 that form flower-like structures at long deposition times. Smaller crystallites were observed on micropillar arrays at pH 8 with “network” like structures observed at long deposition times. Additionally, by controlling the pH of the chemical bath, the hexagonal and cubic crystal phases of CdS were both accessible in high purity at temperatures as low as 85°C.

Synthesis of Titanate Nanotube–CdS Nanocomposites with Enhanced Visible Light Photocatalytic Activity

CdS-1D titanate nanotubes (CdS/TNTs) nanocomposites have been synthesized via a facile one-step in situ hydrothermal method. The structure and properties of CdS/TNTs nanocomposites have been characterized by X-ray diffraction, UV-vis diffuse reflectance spectra, transmission electron microscopy, photoluminescence spectra, nitrogen adsorption-desorption, and electron spin resonance spectra. The results show that (i) as compared to blank-CdS, it is found that the morphology of CdS in the CdS/TNTs nanocomposites can be finely tuned by TNTs formed during the one-step in situ hydrothermal process; and (ii) the CdS/TNTs nanocomposites exhibit remarkably much higher visible light photocatalytic activity than both blank-CdS and blank-TNT toward aerobic selective oxidation of alcohols under mild conditions. Three integrative factors lead to such a drastic photoactivity enhancement for CdS/TNTs nanocomposites. The first one is the different morphology of CdS in the CdS/TNTs nanocomposites from blank-CdS. The second one is the prolonged lifetime of photogenerated electron-hole pairs from CdS in CdS/TNTs nanocomposites under visible light irradiation. The third one is the higher surface area and adsorption capacity of CdS/TNTs nanocomposites than blank-CdS. In addition, the possible reaction mechanism for photocatalytic selective oxidation of alcohols over CdS/TNTs nanocomposites has also been investigated using the radical scavengers technique. It is hoped that this work could promote further interest in fabrication of various 1D TNT-based composite materials and their application to visible-light-driven photocatalytic selective organic transformations.

Towards understanding the nanomaterials characteristics of vapor transported CdS in an open end tube

In this study, the evaporation condensation of CdS was carried out in a quartz tube with an open end. The synthesis was carried out on Au coated Si(100) and quartz substrates. The Au coated Si and quartz substrates were put approximately 1 cm and up to 25 cm away from the alumina boat. It was observed that the materials deposited on the substrates in the reactor tube formed with different colors in different regions. The regions were found to be 6–14 cm, 14–18 cm and 18–24 cm away from the center of the alumina boat and were labeled B, C and D, respectively. The morphology, structural and chemical composition of the obtained materials at different regions were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive analysis of X-ray (EDAX), respectively. EDAX analysis revealed the presence of Cd and S with nearly stoichiometric CdS at region B. At region C a pronounced peak of oxygen was observed together with the peaks of Cd and S. At region D the S peak was diminished. XRD examinations revealed the formation of single crystalline phase of hexagonal CdS in region B. Mixed crystalline phases of hexagonal CdS, monoclinic cadmium sulfite, CdSO3, and cubic CdO were formed in region C. Cubic CdO was formed in region D. The SEM examinations showed that the morphology of CdS was nanowires (NWs) in shape. The morphology of the mixed oxysulfide phase was a mixture between NWs and nanoparticles (NPs). The morphology of CdO was NPs in shape. The optical constants, the thickness and the surface roughness of the prepared nanostructured films were determined by spectroscopic ellipsometry measurements. A model consisted of two layers was used to fit the calculated data to the experimental ellipsometric spectra. The obtained optical constants were compared with those of CdS and CdO obtained by other preparation methods.

Incorporation of cadmium sulfide nanoparticles on the cadmium titanate nanofibers for enhanced organic dye degradation and hydrogen release

Abstract In this study, the effective cadmium sulfide NPs were successfully encapsulated on cadmium titanate electrospun nanofibers. Calcination of electrospun nanofiber mats composed of titanium isopropoxide, poly (vinyl pyrrolidone) (PVP) and cadmium acetate dihydrate with few drops of ammonium sulfide in air at 600 °C led to the production of good morphology of CdS decorated cadmium titanate nanofibers. The morphology and structure of as-synthesized nanocomposites were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). As-synthesized nanocomposites exhibited a strong photocatalytic activity for decomposition of methylene blue (MB) under visible light and showed good hydrogen release from hydrolysis of the ammonia–borane complex. The perfect recovery of catalyst after reaction and its unchanged efficiency for cyclic use showed that it will be an economically and environmentally friendly photocatalyst. The results indicated that the CdS/CdTiO 3 photocatalysts possess improved photocatalytic activity than that of CdTiO 3 alone.

Mineralizer-Assisted Shape-Controlled Synthesis, Characterization, and Photocatalytic Evaluation of CdS Microcrystals

High-quality, well-crystallized, single-crystal, wurtzite CdS hexagonal microtowers (with and without tubular structure) and CdS with octahedral geometry were successfully synthesized by tuning the solvent ratio of water and ethanol for the first time on a large scale without using any catalysts or templates. The products were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry, transmission electron microscopy, and field emission scanning electron microscopy. CdS with microtowers, octahedral geometry, and hexagonal plates was formed by thermal decomposition of cadmium thiocyanate at 400 °C under open atmospheric conditions. The influence of solvent, initial precursor concentration, decomposition temperature, and time on the morphology of CdS was investigated, and the results were discussed. The XRD results showed that the cadmium thiocyanate complex is completely decomposed into CdS at 300 °C for 2 h and the wurtzite phase was formed under all experimental conditions, which opens a door for well-crystallized, single-phase CdS synthesis on a large scale. The diffuse reflectance spectra showed that CdS microtowers have strong visible light absorption compared with the octahedral geometry, revealing the existence of a profound shape−property relationship of CdS. The CdS microtowers with a Pt cocatalyst showed a high rate of photocatalytic hydrogen production from water containing 0.1 M Na2S and 0.1 M Na2SO3 as sacrificial reagents under visible light irradiation (λ ≥400 nm). The possible growing mechanism of various types of the CdS morphology was also discussed.

Cadmium(ii) complexes of N,N-diethyl-N′-benzoylthio(seleno)urea as single-source precursors for the preparation of CdS and CdSe nanoparticles

Cadmium complexes of N,N-diethyl-N′-benzoylthiourea and N,N-diethyl-N′-benzoylselenourea have been used as single-source precursors for the synthesis of HDA capped CdS and CdSe nanoparticles in a predominantly cubic phase, respectively. Both types of particles show quantum confinement effects and close to band edge luminescence. The particle morphology of CdS and CdSe nanoparticles obtained from the thermolysis of bis[N,N-diethyl-N′-(benzoylthioureato)]cadmium(II) and bis[N,N-diethyl-N′-(benzoylselenoureato)]cadmium(II) was found to be independent of the thermolysis temperature and monomer concentration in the ranges examined. The structure of the N,N-diethyl-N′-benzoylthiourea ligand was determined by single-crystal X-ray diffraction.

Electrosynthesis of cadmium sulfide on sulfur- or thiol-modified polycrystalline gold electrodes

This paper describes a two-step electrosynthesis approach for the preparation of CdS semiconductor layers on polycrystalline Au substrates. The sulfide ion precursor required for in situ CdS precipitation can be electrogenerated (via cathodic stripping) either from a pre-formed sulfur layer or a thiol-based self-assembled monolayer on the Au surface. The morphology of CdS formed in the two cases and the corresponding photoelectrochemical behavior are compared and contrasted.

Properties and morphology of CdS compounded TiO2 visible-light photocatalytic nanofilms coated on glass surface

Thin-fobidden-zone CdS compounded TiO 2 films can promote the visible light photocatalytic degeneration efficiency of photocatalytic film greatly. The compounded films are prepared by sol-gel method using spinning technology on the glass surface. Additional TiO 2 layer was coated on the CdS compounded TiO 2 film to inhibit the solubilization of cadmium. Some pore-producing agents, such as trifluoroacetic acid and polyethylene glycol, have been doped in these additional layers. The degradation efficiency under visible light of compounded films for methyl orange is investigated by spectrophotometer. The morphology of glass surface is observed through AFM. The dissolved cadmium of films is detected by atomic absorption spectrometer. As a result, the visible light photocatalytic degradation efficiency of the compounded film is far higher than that of TiO 2 film. The amount of dissolved cadmium of film surface is hardly found after the second layer was coated.

Structure of CdS−Cd−Arachidate/Arachidic Acid Composite Multilayers

A composite multilayer consisting of semiconducting CdS distributed in Cd-arachidate/arachidic acid layers was prepared by exposing the precursor Cd-arachidate multilayers to H 2 S. The structures of the precursor multilayers and the modified multilayers were studied by grazing incidence reflection/diffraction using X-rays from a conventional generator and a synchrotron source. The formation of CdS in arachidic acid/Cd-arachidate composite multilayers resulted in the introduction of a new layered structure with a period of 4.37 nm compared to the precursor multilayer period of 5.55 nm. The reduction in the period of the multilayers is consistent with the observation of a tilted structure found in alkanethiol and H 2 S exposed Cd-stearate multilayers. The lateral morphology ofCdS which is replicated between the successive layers in the vertical direction is different when compared to the head group morphology in the precursor multilayer. The molecular arrangement in the plane of the Cd-arachidate precursor multilayer is found to be orthorhombic while the CdS molecules in the modified multilayer are arranged in a hexagonal array. The lateral size of the CdS domains/particles is found to be 13 nm, at least an order of magnitude greater than the layer thickness. This clearly indicates that the CdS particles are quasi-2D in nature and are disk shaped.

Cubic forms in the surface morphology of CdS evaporated films

CdS films were grown by vacuum evaporation onto muscovite mica substrates. The surface structure of the films was investigated by electron microscopy, electron diffraction and X-ray diffraction. Growth structures typical of cubic symmetry have been observed, and those of the wurtzite-sphalerite and sphalerite-wurtzite transitions are also described. A discussion of experimental results in terms of the nucleation mechanism is given.