CdS Particles Research Articles

Efficient photocatalytic debromination of 2,2ʹ,4,4ʹ-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light

Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2ʹ,4,4ʹ-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho ≫ para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.

Synthesis and characterization of CdS/TiO2 nanocomposite: Methylene blue adsorption and enhanced photocatalytic activities

In this report, CdS/TiO2 nanocomposite was synthesized by hydrothermal method using KOH as an alkaline medium. The prepared sample was calcined at 200 °C for 2 h. The sample was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) analysis, UV–Vis-NIR absorption spectroscopy, Raman spectroscopy and nitrogen adsorption-desorption tests. X-ray analysis confirmed the hexagonal wurtzite/titanate phase formation of nanocomposite. TEM images revealed the titanate nanotube and CdS particle formation of CdS/TiO2 nanocomposite. The presence of functional groups in the sample was analyzed by IR spectroscopy. Band-gap energy of the sample was determined by UV-vis-NIR diffuse reflectance spectrum. Raman intensities confirm the presence of CdS and TiO2 in the synthesized nanocomposite. From BET analysis, surface area of the sample is determined as 31.7 m2/g and an average pore diameter is 10.41 nm. The as-prepared sample was used in the photodegradation reaction of methylene blue (MB) dye under sunlight and analyzed by UV-visible absorption spectroscopy. The results recommend that the nanocomposite exhibited much higher visible light photocatalytic activity for the degradation of methylene blue and the photodegradation efficiency can reach 77% after 180 min.

Unveiling Charge-Separation Dynamics in CdS/Metal–Organic Framework Composites for Enhanced Photocatalysis

Photocatalytic water splitting for H2 production becomes one of the most favorable pathways for solar energy utilization, while the charge-separation dynamics in composite photocatalysts is largely elusive. In the present work, CdS-decorated metal–organic framework (MOF) composites, namely, CdS/UiO-66, have been synthesized and exhibit high H2 production activity from photocatalytic water splitting, far surpassing the MOF and CdS counterparts, under visible light irradiation. Transient absorption (TA) spectroscopy has been adopted in this report to unveil the charge-separation dynamics in CdS/UiO-66 composites, a key process that dictates their function in photocatalysis. We show that, in addition to the preferable formation of fine CdS particles assisted by the MOF, effective electron transfer, which occurs from excited CdS to UiO-66, significantly inhibits the recombination of photogenerated charge carriers, ultimately boosting the photocatalytic activity for H2 generation. This report on charge-separat...

Chalcogenide thin film multilayer structure for solar cell applications

Nanocrystalline semiconductor thin films of TiO2, CdS and CdTe were prepared by various techniques. TiO2 thin films of controlled thickness and optimized electrical properties were prepared by Langmuir Blodgette (LB) technique. CdTe nanoparticles were prepared by hydrothermal technique whereas CdS nanoparticles were prepared by solvothermal technique. Structural, optical and electrical characterizations of TiO2 thin films, CdS and CdTe nanoparticles were carried out. UV–Visible absorption studies indicated that particle size of CdTe was varying with refluxing time. X-ray diffraction studies indicated the CdS particle of size about 2.4 nm with single phase cubic structure and CdTe particles of size 3 nm with crystal phase zinc blende structure. Photosensitivity studies were carried out on Si/TiO2/CdS/CdTe multilayer structure using two different electrolytes (Na2SO4 and mixture of Na2S:Na2SO3) in photoelectrochemical cell (PEC) configuration. Two electrolytes were used to study the PEC effect on photovoltaic properties. The study showed higher photocurrent with Na2S:Na2SO3 electrolyte.

UV-Light-Induced Aggregation of Arsenic and Metal Sulfide Particles in Acidic Wastewater: The Role of Free Radicals.

The removal of arsenic and metals by sulfide (S(-II)) from acidic wastewater is an efficient method. However, the small sulfide particles formed in such a process make solid-liquid separation difficult, which greatly hinders its application. This study investigated the aggregation behavior of different sulfide particles (As2S3, CuS and CdS) under ultraviolet (UV) irradiation. In the dark, the aggregation rate of the arsenic sulfide (As2S3) particles was extremely slow. However, under UV irradiation, the growth of the As2S3 particles was significantly enhanced. A possible mechanism of UV-light-induced aggregation of As2S3 particles was proposed. The HS· and ·OH radicals formed by a series of photochemical reactions can efficiently attack the S(-II) in the As2S3 particle, leading to the formation of an intermediate species, [As2S2-S·]+. Then, two [As2S2-S·]+ species combine to form [As2S2-S-S-S2As2]2+. The formation of [As2S2-S-S-S2As2]2+ results in the attenuation of the electronegativity and the rapid aggregation of the sulfide particles. In addition, the small S0 particles generated in irradiated As2S3 system can efficiently coalesce into As2S3 particles. The CuS and CdS particles should have similar aggregation mechanisms. This study proposed a potential method for sulfide particle aggregation and provided a theoretical foundation for the development and application of UV-light-induced sulfide particle aggregation technology.

In Situ Formation of Leaf-Like Ag2S/CdS Heterojunction Photocatalyst Harnessing Vis–NIR Light for Photodegradation of Organic Pollutants

The Ag2S/CdS composite photocatalyst with a leaf-like structure was synthesized by loading the Ag2S nanoparticles on the surface of the hydrothermally synthesized CdS particles. The UV–Vis–NIR absorption spectroscopy results reveal that the Ag2S/CdS composite photocatalyst exhibits a wide-spectrum response from ultraviolet (UV) to near-infrared (NIR), demonstrating its potential for effective utilization of solar energy. The scanning and transmission electron microscopic observations show that Ag2S nanoparticles with the size of about 20 nm are successfully embedded on the surface of leaf-like structure of CdS. Among the samples loaded with different molar percentages of Ag2S nanoparticles, the 5%-Ag2S/CdS composite photocatalyst exhibits a higher photocatalytic efficiency than the individually synthesized CdS and Ag2S for the degradation of Rhodamine B (RhB) and methyl orange (MO) under LED visible light irradiation. Furthermore, the 5%-Ag2S/CdS composite photocatalyst also exhibits a photocatalytic activity for the degradation of RhB under 850 and 940 nm monochromatic light irradiation. The results of the photocatalytic activity tests performed with various scavengers confirm that ·O2− plays a key role in the photodegradation of RhB. An enhanced photocatalytic performance of the Ag2S/CdS composite photocatalyst is directly attributed to the formation of a heterojunction between Ag2S and CdS. The developed composite photocatalyst can harness a greater share of the solar spectrum from visible to near infrared region and generate the photoinduced charge carriers more efficiently.

Optical Properties of CdS Quantum Dots on Graphene

Hybrid systems based on graphene and semiconductor quantum dots are prospective materials for optoelectronics and photonics. In this work, electronic structure and dielectric properties of small particles of cadmium sulfide on the surface of graphene were studied using the density functional theory. The optical spectrum of this hybrid structure depends on the orientation of the nanoparticle relative to graphene due to the interaction between electrons of sulfur atoms on the surface of the CdS particle and π-orbitals of carbon atoms.

Hydrothermal synthesis and sol-gel methods for CdS particle production in different morphologies and their use in wastewater applications

Bu calismada, iki farkli metot kullanilarak CdS nanopartikulleri farkli boyutlarda ve morfolojilerde sentezlenmistir. Ilk olarak, hidrotermal sentez yontemi ile hem karnabahar tipi CdS mikrokurelerin hem de CdS nanocicek turu mikroyapilarin sentezleri teflon hazneli celik reaktorlerde gerceklestirilmistir. Karnabahar tipi CdS mikrokurelerin sentezinde polietilen glikol ve tiyoasetamid kullanilirken, nanocicek CdS mikroyapilarin sentezlerinde sulfur kaynagi olarak tiyoure kullanilmistir. Diger bir yontem olan sol-jel metodu ile de caplari yaklasik 200 nm olan kuresel CdS ve Ag/CdS nanopartikuller hazirlanmistir. Bu metotta, polietilen glikol su icerisindeki cozunurlugu ve yuksek viskozitesi sayesinde nanokristallerin buyumelerinin kontrollerini saglayarak stabilizor olarak kullanilmistir. Her iki metot ile de basarili bir sekilde farkli boyutlarda ve sekillerde CdS mikro- ve nanoyapilar hazirlanmistir. Bu partikuller, metil oranj (MO) boyasinin fotodegradasyonunda kullanilmistir. Ortaya cikan sonuclar, sentezlenen CdS partikullerinin MO boyasinin fotodegradasyona ugratarak atik su uygulamalarinda potansiyel kullanimlari olabilecegini gostermektedir. Floresans spektroskopi olcumleri ile CdS yapilarinin enerji band araliklari belirlenmistir. X-isini kirinim yontemi (XRD), gecirimli elektron mikroskobu (TEM) ve taramali elektron mikroskobu (SEM) cihazlari yapilarin karakterizasyonunda kullanilmistir. Ayrica MO boyasinin atik sulardan giderim calismalarinda UV-vis spektrofotometresi kullanilmis olup, CdS partikullerinin boya degradasyon yuzdesi ve adsorpsiyon kapasitesi (qe) degerleri hesaplanmistir.

Crystallization and luminescence of Pr3+-doped CdS QDs silicate glass

CdS QDs (quantum dots) were precipitated in the Pr3+-doped silicate glass by the melting-quenching method. The crystallization behavior and luminescent property of the Pr3+-doped CdS QDs silicate glass were analyzed by XRD, Raman, TEM, UV–Vis–NIR scanning spectrophotometer and fluorescence spectra. It was found that with the increase in the heat-treatment temperature, the size of CdS particles increased from 2.30[Formula: see text]nm to 3.63[Formula: see text]nm, while red-shift was observed in absorption and fluorescence spectra excited at 370[Formula: see text]nm. Fluorescence measurements of the glass showed that the growth of CdS QDs induced a considerable enhancement in the emission spectra of Pr3+, and the sensitization is due to the energy transfer from CdS QDs to Pr3+ ions.

Chemical deposition of CDS films from ammoniac-thiourea solutions

This paper investigates the process of chemical deposition of CdS films from ammonia-thiourea solutions. It was established that a change in the turbidity of solution occurs in the process of chemical deposition. The results of visual observations and measurement of turbidity of solution allowed us to establish that these dependences could be used to monitor the status of the process. Visual observations correlate with the obtained dependences for turbidity and suggest that the chemical deposition of CdS includes the accumulation of colloidal-dispersed precipitate in the volume of solution, agglomeration of CdS particles, and a stationary mode of the CdS film growth at the surface of a sample. The first stage of the process is matched by a sharp increase in the turbidity of solution; the second stage is accompanied by the emergence of a maximum in the dependence. No significant change in turbidity occurs at the third stage. The observation of morphology of the resulting precipitate allowed us to establish working concentrations of reagents in solution, which ensure obtaining a high-quality CdS film with a thickness not less than 100 μm. The working concentrations of cadmium chloride, ammonia, and thiourea are, respectively, 1.8, 0.6, and 8.4 g·l –1 . It was assumed that the CdS formation is accompanied by the formation of thiourea. This is confirmed by data on the analysis of a working solution. An analysis of the solution revealed high concentrations of the CO 3 2– ions, which are a product of the thiourea decomposition. The data obtained are a preliminary stage in the development of a technology of chemical deposition of CdS films from ammonia-thiourea solutions.

Study of the photocatalytic degradation of toluene over CdS-TiO2 nanoparticles supported on multi-walled carbon nanotubes by back propagation neural network

ABSTRACTTo optimize the photocatalytic conditions for the degradation of volatile organic compounds (VOCs), this study focused on the application of a back propagation (BP) neural network to determine the photocatalytic performance of CdS-TiO2 nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) for toluene degradation. This was accomplished by first characterizing the photocatalyst using transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD) and UV-visible absorption spectrum (UV-vis). It was observed that TiO2 and CdS particles were uniformly supported on the inner and outer walls of MWCNTs as a composite catalyst. Second, employing a test that included a training set and a prediction set, the results showed that the designed BP neural network exhibited a fast convergence speed and the system error was 0.0009702. Furthermore, the predictive values of the network were in good agreement with the experimental results, and the correlation coefficient was 0.9880. These results indicated that the network had an excellent training accuracy and generalization ability, which effectively reflected the performance of the system for the catalytic oxidation of toluene on a CdS-TiO2/MWCNTs photocatalyst.

Effect of sonication time on the synthesis of the CdS nanoparticle based multiwall carbon nanotube – maleic anhydride – 1-octene nanocomposites

ABSTRACTEffect of sonication time on the synthesis of the CdS nanoparticles within the matrix obtained through the covalent functionalization of multiwall carbon nanotube (MWCNT) with maleic anhydride (MA) – 1-octene copolymer was investigated. Cadmium chloride and thiourea were used as the raw materials. MWCNTs used for the matrix were synthesized by Catalytic Chemical Vapor Deposition using Fe-Co/Al2O3 as the catalyst. The obtained nanostructures were characterized by FTIR, XRD, Raman spectroscopy, TEM, SEM, TG and UV-Vis spectroscopy. Electrophysical properties of the polymer nanocomposites obtained using different periods of time for sonication were comparably investigated. The average CdS particle diameter was between 3.9–7.9 nm as confirmed independently by TEM and XRD. UV-Vis spectroscopy revealed that the obtained nanostructures are appropriate base materials for making optical devices.

CdS particles modified TiO2 coatings formed by plasma electrolytic oxidation with enhanced photocatalytic activity

CdS particles modified anatase TiO2 photocatalysts were formed on titanium substrate by plasma electrolytic oxidation for 2 min in supporting electrolyte (10 g/L Na3PO4⋅12H2O) with addition of CdS particles in concentrations up to 8 g/L. Content of CdS particles incorporated into TiO2 coatings depends of CdS particles concentration in supporting electrolyte, while surface morphology, phase structure and absorption properties of formed coatings were not significantly influenced by the addition of CdS particles. In contrast to pure TiO2 coatings, TiO2/CdS coatings exhibit enhanced photocatalytic activity (PA) in the degradation of methyl orange, used as a model organic pollutant, under simulated solar irradiation. The highest PA was observed for TiO2/CdS coating formed in supporting electrolyte with addition of 0.4 g/L of CdS particles. Photoluminescence measurements indicate that enhanced PA is related to the reduction of the recombination rate of photogenerated electron/hole pairs as a result of TiO2 and CdS coupling.

Enhanced photocatalytic hydrogen production of AgMO3 (M = Ta, Nb, V) perovskite materials using CdS and NiO as co-catalysts

The synthesis of AgMO3 (M = V, Nb, Ta) perovskite materials by solid state reaction and the additional deposition of CdS and NiO particles as co-catalysts using hydrothermal and impregnation methods, respectively, were performed in order to investigate their photocatalytic activities for hydrogen production. The structural and morphological properties were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). UV–vis spectroscopy (UV–vis) and physical adsorption analysis by BET method were used for optical and textural properties. The photocatalytic activities for hydrogen production were carried out under UV light in a Na2SO3 aqueous solution. The effect of loading amount and the nature of co-catalyst used is also discussed. The results showed that the electronic band structure of the AgMO3 (M = Ta, Nb, V) perovskite materials and the co-catalysts play an important role in the photocatalytic activity due to their band positions that allow an improvement in the photogenerated charge carrier transfer and in the hydrogen production amount. The best photocatalytic hydrogen production (4645 μmol g−1) was obtained with 5 wt% loading of CdS co-catalyst onto AgTaO3 perovskite compared to AgTaO3 material loaded with 2 wt% of NiO co-catalyst (1847 μmol g−1).

45 keV N5+ ions induced spikes on CdS thin films: Morphological, structural and optical properties

CBD grown CdS thin films were implanted using 45 keV N5+ ions of different fluences from 1 × 1015 to 5 × 1016 ions/cm2 by electron cyclotron resonance (ECR) ion source. Structural properties of pristine and ion beam implanted films were studied by glancing angle X-ray diffraction (GAXRD) and it becomes a hexagonal structure of polycrystalline thin films. High resolution scanning electron microscopy (HRSEM) studies shows that the pristine sample forms agglomerated particles of CdS. After ion implantation of higher fluence 5 × 1016 ions/cm2, numerous defects created spikes on the surface of the film. The spike formation explained with the help of nuclear elastic collisions. The optical band gap energy of N5+ ion implanted thin films was reduced with increases of ion fluences. This is probably due to lattice disorder produced band-tailing and/or creation of impurity states. The red, yellow, green and band edge emissions were studied in correspondence with photoluminescence spectrum.

Ultrasonic chemical synthesis of CdS-reduced graphene oxide nanocomposites with an enhanced visible light photoactivity

In this study, we report a facile ultrasonic method to prepare a series of CdS and reduced graphene oxide (CdS/rGO) composites with different weight ratios of graphene at temperature as low as 70 °C for 20 min by employing ammonia as a complexing agent of Cd2+ ions and reducing agent of graphene oxide (GO). Pure CdS particles had a poor crystallinity and aggregated to large particles size. As GO was incorporated into CdS, a uniform dispersion of CdS particles with high crystallinity on rGO sheets was clearly observed. The as-prepared CdS/rGO composites have a wide and strong photo absorption in the visible region and display a substantially improved photocatalytic activity for the degradation of methylene blue under visible light irradiation by forming a heterojunction of rGO and CdS. However, too much rGO will shield the light of the active sites for the CdS nanoparticle surface and thus limit further improvement in the photocatalytic efficiency.

Stability studies of CdS sensitized TiO2 nanotubes prepared using the SILAR method

Titania nanotubes sensitized with CdS nanoparticles of different sizes and amounts were prepared using the successive ionic layer (SILAR) deposition method. UV/visible spectra indicate a red shift in CdS absorption upon increasing the number of SILAR cycles this is due to an increase in amount and size of CdS particles on the surface of titania nanotube. The stability of CdS particle sensitized on the surface of titania nanotubes were monitored using X-ray photoelectron spectroscopy (XPS). The formation of CdSO4 species on the surface of CdS particles was evident from the XPS analysis. Smaller CdS particles, formed using a lower number of SILAR cycles, are more prone to oxidation than the larger particles formed using a greater number of SILAR cycles. The photocatalytic activity and solar cell efficiency is found to be dependent on the number of SILAR cycles employed.

Noble metal-free metal-organic framework-derived onion slice-type hollow cobalt sulfide nanostructures: Enhanced activity of CdS for improving photocatalytic hydrogen production

The hollow materials have played a significant role in cutting-edge innovations for energy conversion due to their peculiar properties and their wide range of potential applications. These materials show great promise for the development of cleaner power sources to address growing environmental concerns at a time of increasing global demand for energy. Noble metal-free MOF-derived onion slice-type hollow structured Co4S3 was developed and embedded with CdS nanoparticles for photocatalytic hydrogen production. The incorporation of Co4S3 with the CdS particles effectively accelerated charge separation and transfer in photocatalytic reactions due to the low density, hollow interior, and shell permeability of the onion-type composite. The optimized Co4S3/CdS photocatalyst led to an enhanced rate of H2 production of 12,360μmolh−1g−1 under simulated solar light irradiation; this value is 26-fold greater than that of the pristine CdS nanoparticles. The Co4S3/CdS composite exhibited remarkably stable photocatalytic performance for up to 65h and could be reused in five successive cycles. Furthermore, to the best of our knowledge, this is the highest H2 production rate achieved with cobalt sulfide-based CdS nanoparticle photocatalysts in the photocatalysis of water under simulated solar light irradiation. Owing to its low cost and high efficiency, this photocatalytic system should hold great potential for the development of highly efficient photocatalytic materials for use in various fields.

Structural, optical and morphological properties of CdS nanoparticles synthesized using hydrazine hydrate as a complexing agent

The complexing agent plays an important role in the synthesis of nanoparticles. Here we report on the synthesis of nanocrystalline CdS by a simple chemical precipitation method using hydrazine hydrate as a complexing agent. The reaction was carried out in an aqueous medium at constant temperatures with continuous stirring. Samples were grown at various temperatures ranging from 40 to 70 °C. The as-grown samples were characterized using powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM/HRTEM),Fourier transform infrared spectroscopy (FTIR),UV-visible spectroscopy and energy dispersive analysis of X-rays (EDX). XRD results confirm the formation of nanocrystalline CdS with the crystallite size increasing from 3 to 15 nm as the growth temperature is increased from 40 to 70 °C. TEM/HRTEM images show that the grain size of the CdS particles is in the range 5–10 nm, the grain size increasing with growth temperature, agreeing with XRD results. The optical band gaps of the samples are blue shifted as the growth temperature is reduced (resulting in a decrease in the crystallite size), confirming the quantum confinement of electrons in the CdS nanoparticles. The results show that the structural and optical properties of the CdS nanoparticles can be controlled by the use of hydrazine hydrate.

Optimization of chemical bath deposited cadmium sulfide buffer layer for high-efficient CIGS thin film solar cells

An optimization of CdS chemical deposition process is presented in order to fabricate high quality CdS buffer layer for high-performance CIGS thin film solar cells. It is found that the heterogeneous and homogeneous reaction can be regulated conveniently by changing the concentration of cadmium acetate. No obvious large CdS particles on the surface of CdS film can be observed due to the dominant heterogeneous reaction and suppressed homogeneous precipitation under the suitable concentration of cadmium acetate. The device with CdS buffer layer deposited at 0.052M cadmium acetate shows the best efficiency of 11.42%. The performance of the device can be further improved by post-annealing treatment in air. An improved champion efficiency of 12.57% is achieved at the annealing temperature of 180°C.