CdS Samples Research Articles

UV-light-driven photocatalytic degradation and antimicrobial properties of efficient ternary semiconductor CdxAg1–xS nanocomposites

The objective of this research was to prepare and characterize the solvent-free ternary semiconductor CdxAg1–xS nanocomposites as photocatalysts by a simple hydrothermal method using without any surfactant. We have accessed the photocatalytic ability of the prepared composites in the degradation of pesticides under simulated UV light irradiation. The Cd0.5Ag0.5S composites show a significant photocatalytic activity, higher than the bare CdS and Ag2S samples. It indicates that the heterostructured combination of Ag and CdS provides synergistic photocatalytic activity through an efficient electron transfer process. The stability and reusability assays indicated that the Cd0.5Ag0.5S composite retained more than 90% of activity after five cycles of use. On the basis of the results, a possible photocatalytic mechanism of the prepared samples was proposed. The synthesized CdS, Ag2S, and Cd0.5Ag0.5S samples were screened against selected bacterial and fungal species. The investigated results confirm the synthesized Cd0.5Ag0.5S is a potential candidate for antimicrobial activity applications.

Microstructural and magnetic characteristics of ceramic dispersion strengthened sintered stainless steels after thermal ageing

The effect of the ultrafine grained silicon nitride and yttria addition to the morphological, structural, mechanical and magnetic properties of the ceramic dispersion strengthened 316 L stainless steels prepared by powder technology has been studied. Four composites have been prepared: 316 L/0.33 wt.% Si3N4, 316 L/1 wt.% Si3N4 (CDS) and 316 L/0.33 wt.% Y2O3, 316 L/1 wt.% Y2O3 (ODS). Spark plasma sintering (SPS) was used for fast compaction of milled composite powders. The hardness values have been found to be significantly higher in the cases of CDS and ODS samples in comparison to reference sample, whereas the ODS composites had lower smaller hardness than the CDS composites regardless the content of additives. The magnetic characterization of samples demonstrated that the samples exhibit ferromagnetic property already before ageing and a larger ferromagnetic component was observed as a result of thermal aging. It was proven that in the case of ODS and CDS samples with a low amount of Y2O3 or Si3N4 the saturation magnetization was slightly dependent on ageing time, however, it exhibited a noticeable change with ageing both at 600 and 800 °C for samples containing higher amount of additives.

Surface modification of CBD-grown CdS thin films for hybrid solar cell applications

The influences of interfacial modification by various dyes (Eosin-Y, D205, N719 and N3) on structural, morphological, optical and electrical properties of CdS-based hybrid solar cells are investigated. Structural properties showed the cubic growth of chemical bath deposited CdS thin films. Morphological analysis indicated that CdS specimen had a smooth and crack-free surface whereas P3HT layer coated on CdS thin films displayed spherical grains with nonuniform distribution. According to Tauc’s estimation conclusions, CdS and P3HT layers exhibited band gaps of 2.98 eV and 1.98 eV, respectively. The surface modification of CdS thin films by diverse dyes led to an increase in the absorption spectra of the CdS samples. Photoluminescence data showed that surface treatment of CdS samples by diverse dyes caused a decrease in the luminescence intensity of the CdS-based hybrid solar cells, meaning that efficient exciton dissociation was obtained. All the devices showed an obvious photovoltaic effect as a result of current density-voltage (J–V) curves. Furthermore, the highest solar cell efficiency was achieved for ITO/CdS/N3/Ag device as 0.322%, which could be ascribed to the surface modification of CdS thin films, giving rise to a formation of better interface between CdS and P3HT layers.

Photocatalytic Performance of Cubic and Hexagonal Phase CdS Synthesized via Different Cd Sources

CdS has been widely used in photocatalysis, by virtue of its sensitivity to visible-light irradiation. But CdS has two crystalline phases, which are not equally well understood. Hence, we synthesized cubic phase and hexagonal phase hierarchical CdS with different Cd sources by the hydrothermal method. These as-prepared CdS samples were characterized by powder x-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), ultraviolet–visible spectrophotometer (UV–Vis), and room temperature photoluminescence (PL). Photocatalytic degradation of methylene blue was evaluated under simulated visible-light irradiation. PXRD results revealed that the CdS samples manifested a cubic phase when the Cd source was CdCl2, but the CdS assumed a mixed hexagonal and cubic phase when the Cd source was Cd(NO3)2. FESEM results indicate that the morphologies of CdS are both flower-like structures. The optical energy band gap of cubic phase CdS is 2.26 eV, but mixed hexagonal and cubic phase CdS is 2.24 eV according to UV–Vis results. PL results show that CdS samples of both phases have a similar emission peak near 560 nm, which is consistent with UV–Vis absorption spectrums. In addition, mixed hexagonal and cubic phase CdS exhibits better photocatalytic activity than cubic phase CdS.

Determination of optimum Er-doping level to get high transparent and low resistive Cd1 − xErxS thin films

Cd1 − xErxS (x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10) thin films were produced by a chemical route on glass slides. The structural, morphological, optical and electrical properties of the grown samples were studied to obtain the optimum Er-doping level. Structural properties indicated that specimens had a hexagonal structure. Morphological analysis showed that the grain size of pristine CdS thin films remarkably reduced with rising Er-doping. The presence of Er atoms in CdS host structure was proved by energy dispersive of X-ray spectroscopy (EDS). The transparency of CdS thin films substantially improved after 10 at.% Er-doping and a gradual decrease was acquired in the band gaps of the CdS samples with the increase of Er-doping. Photoluminescence data approved the existence of two main peaks corresponding to the green and yellow regions. Electrical properties of pristine CdS thin films were enhanced by Er-doping and the best electrical conclusions were obtained for Cd0.94Er0.06S thin films. Thus, it can be brought to an end that Er-doping enhanced both optical and electrical properties of pristine CdS thin films, which are of vital importance in optoelectronic applications.

Effect of V and Y doping on the structural, optical and electronic properties of CdS (hexagonal and cubic phases)

Nano Cd1−xYxS and Cd1−xVxS (0 ≤ x ≤ 0.2) systems were synthesized by a thermolysis method. X-ray phase analysis indicated the presence of two phases, cubic and hexagonal structures, for some samples. The effect of doping on the cell parameters, Cd-tetrahedron dimension, crystallite size and the mixed phases’ percentages in the sample were examined applying X-ray Rietveld method. The energy gap of Y- or V-doped CdS was determined by ultraviolet spectroscopy technique. It is found out that the energy gap of V-doped CdS is less than the corresponding Y-doped CdS samples. Density function calculation (DFT) was used to confirm the decreasing in energy gap upon doping, and also to study the changes in absorption and dielectric properties of doped and undoped CdS samples in both cubic and hexagonal phases. The photoluminescence measurements revealed the presence of extra sub emissions spectra (yellow and green) upon doping CdS with Y or V compared with undoped CdS sample.

Microstructural and Optical properties of Silver doped Cadmium Sulphide Nanoparticles

Abstract The nanoparticles of Ag-doped CdS have been successfully synthesized at room temperature by sol-gel method using cadmium acetate, silver nitrate and sodium sulphide as precursor materials. The structural and morphological analyses have been performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDAX). The results of structural characterizations show the formation of Ag-doped CdS nanoparticles in a single phase without any impurity. The average crystallite size of all nanoparticles was calculated by Debye−Scherrer formula which came out to be 6 nm for pure CdS and increased to 10 nm for Ag-doped CdS nanoparticles. The optical absorption of the prepared Ag-doped CdS samples was determined by UV-visible spectrophotometer in the range of 350 to 800 nm. The band gap energy for pure CdS was estimated by Tauc relationship and found to be 2.7 eV, whereas it decreased to 2.3 eV for the Ag doped CdS.

A research on growth and characterization of CdS:Eu thin films

Chemical spray pyrolysis-grown CdS thin films including various quantities of Eu atoms (from 0 to 10 at.%) were synthesized on glass slides. The detailed physical properties of the produced CdS and CdS:Eu thin films were explored. Structural analysis showed that Eu-doping enhanced the crystal quality of CdS thin films until 10 at.% Eu-doping and further Eu-doping treatment led to a distortion in the CdS structure. In addition, the crystallite sizes of CdS thin films dropped from 36.2 to 32.4 nm as Eu-doping level increased to 10 at.%. Morphological data showed that increasing Eu-doping remarkably varied the surface morphology of CdS thin films forming smaller grains. Chemical content examinations approved the presence of Eu atoms in CdS structure. From the optical measurements, it was obtained that more transparent CdS thin films with a maximum transmittance of 68% at 820 nm were created after 10 at.% Eu-doping and bandgap values of samples reduced from 2.58 to 2.47 eV with rising of Eu-doping from 0 to 10 at.%. Room temperature photoluminescence data demonstrated the formation of two essential peaks for all the samples, which are in turn related to green and yellow bands. Electrical investigation pointed out that Eu-doping enhanced the carrier density of CdS thin films from 4.38 × 1013 cm− 3 to 2.46 × 1014 cm− 3 and dropped the resistivity of CdS samples from 2.59 × 104 Ω cm to 5.85 × 103 Ω cm until 6 at.% and further increment of Eu-doping paved the way to get worse electrical data. Thus, it can be brought a conclusion that Eu-doping not only improved the optical properties of CdS thin films, but also restored the electrical properties, which are able to use in the opto-electronic devices.

Cationic and anionic modification of CdS thin films by surface chemical treatment

Structural and physical properties of thin solid films can be modified by surface treatment. In this work, chemical bath deposited CdS thin films were treated both by a mercury chloride solution and by a saturated H2S gas. The effect of these treatments on electrical properties is clearly observed. Hg2+ doped CdS films show the highest dark and photo-conductivities, whereas the sulfurized CdS films become photo-insensitive. In Hg2+ doped CdS samples, new crystalline Hg3S2Cl2 and Hg2(ClO4)24H2O phases are found, and particle size reduction is observed at the surface. Both optical and electrochemical Mott-Schottky (M–S) analysis suggest an intraband level in the electronic structure of Hg2+ modified CdS. Sulfurized CdS films, on the other hand, keep unchanged their crystalline and morphological structure, as well as optical properties. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and M–S analysis indicate an increase of sulfur concentration at the surface of sulfurized CdS thin films, leading to a more stoichiometric CdS compound, which used to have lower conductivity. It demonstrates that ion exchange process or cationic substitution is effective for structural and physical property modification, whereas a gaseous saturation method or anionic modification results in a notable surface energy alteration in thin solid CdS films.

CdS nanoparticles sensitized high energy facets exposed SnO2 elongated octahedral nanoparticles film for photocatalytic application

The fabrication of well-defined semiconductor based SnO2 heterostructure is still a great challenge. In this study, SnO2(TiO2) elongated octahedral nanoparticles film was directly produced on FTO substrate by hydrothermal approach and TiCl4 post-treatment. As a light absorber, CdS nanoparticles were assembled onto the TiCl4 -treated SnO2 elongated octahedral nanoparticles (SnO2(TiO2)). We investigated the photocatalytic and photoelectrochemical properties of the prepared SnO2(TiO2)/CdS films. The study found that the prepared SnO2(TiO2)/CdS(6) heterostructure showed much higher photocatalytic activities for the degradation of the methyl orange (MO) under visible light irradiation in comparison with individual SnO2(TiO2) film photocatalyst. The significantly enhanced photocatalytic performance of the SnO2(TiO2)/CdS(6) sample is due to the absorption of visible light and the formation of type-II heterostructure, which plays a role in the effective charge separation. Moreover, these SnO2(TiO2)/CdS films photocatalyst are directly produced on FTO substrates, making the photocatalyst collection and recycling easier than the powders photocatalyst.

High-performance visible light photocatalytic activity of cobalt (Co) doped CdS nanoparticles by wet chemical route

The role of cobalt (Co) dopant on structural, morphological, optical and photocatalytic properties of CdS nanoparticles were methodically reported. XRD analysis confirms that both pure and Co-doped CdS samples have cubic structure with no impurity phases detected and the results are good in agreement with the standard JCPDS value (Card No. 80-0019). TEM images reveal the spherical morphology with an average diameter of around 15–35 nm. A noticeable red-shift of absorption edge and bandgap narrowing can be attributed to the inclusion of cobalt ions and creation of defect levels in the bandgap, which is confirmed by UV analysis. Photoluminescence spectra show defects-free nature of synthesized nanoparticles. The functional groups and chemical interaction were determined by FTIR spectra. The photodegradation of MB dye with Co-doped CdS is more efficient under visible light compared to pure CdS. The 15 mol% Co-doped CdS acts as an efficient photocatalyst. The presence of Co2+ generated electron and holes and prolonged the recombination rate by introducing the temporary trapping sites, which essentially causes to improve the photocatalytic efficiency of the synthesized samples. The possible photocatalytic mechanism by Co doping is also discussed in detail.

Perovskite Oxide LaNiO3 Nanoparticles for Boosting H2 Evolution over Commercial CdS with Visible Light.

LaNiO3 /CdS heterojunction photocatalysts are constructed by compositing LaNiO3 nanoparticles with commercially available CdS, and are used for efficient photocatalytic splitting of H2 O with visible light. The LaNiO3 /CdS hybrids are characterized systematically using a series of physicochemical techniques. The photocatalytic activity of the perovskite hybrids is examined by H2 evolution with Na2 S-NaSO3 as the hole scavenger. The optimized LaNiO3 /CdS sample without the assistance of any cocatalyst (e.g., Pt) delivers a high H2 production rate of 74 μmol h-1 (e.g., 3700 μmol h-1 g-1 ), which is substantially superior to the individual LaNiO3 and CdS. Besides, the composite photocatalyst also manifests high stability. The greatly improved H2 production performance of LaNiO3 /CdS is attributed to the facilitated separation and transport of photoinduced charge carriers, as evidenced by photoelectrochemical (PEC) analyses, such as photoluminscence spectroscopy, transient photocurrent responses, and electrochemical impedance spectroscopy. Moreover, a probable photocatalytic mechanism of the H2 evolution reaction is proposed on the basis of the results of the catalysis evaluation and PEC tests.

Effect of gamma irradiation on the structural and optical properties of PVA/CdS nanocomposite films prepared by ex-situ technique

ABSTRACTFor a comprehensive understanding of the PVA/CdS nanocomposite properties, it is essential to select the suitable method for their preparation as well as elucidate the interfacial interactions, which still need support. CdS nanoparticles have been prepared by thermolysis method under the flow of nitrogen. Rietveld refinement of x-ray data shows that all the CdS samples have both cubic and hexagonal structures. Then PVA/CdS films were prepared by ex-situ technique. Samples from PVA/CdS nanocomposite have been irradiated with gamma doses in the range 10–120 kGy. The implanting of CdS NPs into PVA matrix was confirmed by XRD hand in hand with UV–vis and FTIR spectroscopic techniques. UV/VIS absorption spectra confirm the formation of hybridized film CdS/PVA nanocomposite with a refractive index in the range of 1.32–1.48 (at 500 nm). UV/VIS measurements were also used in calculating different optical parameters such as refractive index, extinction coefficient and optical band gap energy. Additionally, Tauc’s relation was used to determine the type of electronic transition. It is found that the gamma irradiation in the dose range 30-90 kGy led to a more compact structure of PVA/CdS nanocomposite and causes proper dispersion of CdS nanoparticles in the PVA matrix. This led to the formation of coordination reaction between OH of PVA and CdS nanoparticles, resulted in an increase in refractive index and the amorphous phase. Also, the gamma irradiation reduces the optical energy gap from 4.53 to 2.19 eV, and accompanied with an increase in the Urbach energy from 2.28 to 4.46 eV, at that dose range which could be attributed to the increase in structural disorder of the irradiated PVA/CdS nanocomposites due to crosslinking. Further, the color intensity ΔE, which is the color difference between the non-irradiated sample and the irradiated ones, was increased, from 0 to 10.8, with increasing the gamma dose, convoyed by an increase in the red and yellow color components.

Inhibited photocorrosion and improved photocatalytic H2-evolution activity of CdS photocatalyst by molybdate ions

For CdS photocatalyst as one of the photocatalytic H2-evolution materials, both photocatalytic performance and stability are the main challenge owing to the recombination of photogenerated charge pairs and serious photocorrosion. In this paper, molybdate ions were injected into the CdS suspension in lactic acid solution as sacrificial agent during photocatalytic H2-evolution process (the resultant sample was denoted as CdS(M)). The results indicated that the color of CdS(M) suspension was lighter than that of original CdS suspension after the illumination, namely, molybdate ions can reduce the oxidation of S2− to S0 from the CdS lattice and effectively suppress the photocorrosion of CdS. Simultaneously, the photocatalytic H2-evolution performance of CdS(M) was obviously increased. When the concentration of Na2MoO4 was 22 μmol L−1, the H2-evolution rate of CdS(M-22) reached the highest value (42.49 μmol h−1), which was 2.51 times as high as that of the CdS sample (16.90 μmol h−1). The mechanism of improved photostability and photocatalytic activity of CdS by the injection of molybdate ions is that the molybdate ions can quickly capture H+ ions in solution to form Calvin-cycle-like pathway for interfacial catalysis reactions and promote the ionization of lactic acid to inhibit the oxidation of S2− to S0 on the CdS surface by trapping the photogenerated holes for the stability of CdS. This work may provide a valuable strategy how the photocorrosion of CdS can be overcome with the enhanced photocatalytic H2-evolution performance.

Structural and Photoluminescence Characteristics of Cu Doped CdS Nanoparticles

EDTA surfactant assisted bare and Cu doped CdS nanoparticles were prepared by simple chemical coprecipitation method. As the prepared samples were characterized by energy dispersive analysis of X-rays (EDAX), X-ray diffraction patterns (XRD), transmission electron microscopy (TEM), Raman spectroscopy and photoluminescence spectroscopy (PL). Existence of Cu in host lattice with near stoichiometric ratio was corroborated by EDAX spectra. X-ray diffraction patterns revealed that cubic structure as that of CdS host lattice. TEM images suggested that spherical nature of nanoparticles with a size ranging from 4–6 nm. Room temperature photoluminescence (PL) spectra revealed that pristine host lattice nanoparticles demonstrate a strong green emission peak located at 525 nm as well as weak red emission shoulder situated at 598 nm. Auxiliary in Cu doped CdS samples, the luminescence intensity was gradually reduced as well as the green emission peak was shifted to red region (660 nm). With increase of Cu content in host matrix a red shift is found in the PL emission peak.

Facile preparation of mixed-phase CdS and its enhanced photocatalytic selective oxidation of benzyl alcohol under visible light irradiation

Selective oxidation is one green technique for routine organics synthesis and environmental remediation. However, the conversion ratio resulted from environment-friendly method employing traditional photocatalytic materials like CdS is relatively low as compared with homogeneous catalytic reaction. Herein, in this paper, a facile method is reported to prepare mixed-phase CdS nanocrystals at room temperature. The as-prepared CdS samples were characterized by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectra (DRS), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic oxidation of benzyl alcohol into benzaldehyde catalyzed by as-prepared CdS was carried out with high conversion of 68% generated within 60 min using O2 as a benign oxidant under ambient condition. The enhanced catalytic activity could be attributed to the mixed-phased crystal structure which facilitates the separation of photogenerated charge carriers.

Optical and electrical optimization of dysprosium-doped CdS thin films

As-grown and Dy-doped CdS thin films containing concentrations of 1, 2, 3, 4 and 5 at.% Dy atom were prepared via chemical spray route on glass substrates. The constructed thin films were searched through analyzing their structural, morphological, optical and electrical features. X-ray diffraction (XRD) surveys showed that as-grown and Dy-doped CdS thin films had hexagonal structure and the preferential orientation was along (101) plane for as-grown, 1 and 2 at.% Dy-dopings. But further dopings (3 and 4 at.%) caused more random orientation, especially for the case of 5 at.%, the preferred orientation changed to (002) plane. The crystallite size progressively lessened from 39 to 27 nm with increasing Dy-doping. The existence of a close relation between grain shape and the preferential orientation appeared as compared to micrographs of scanning electron microscopy with XRD data. 5 at.% Dy-doped CdS thin films possessed the best transmittance (over 80%) among all the samples. Except for 2 at.% Dy-doped CdS sample, the other samples had almost a band gap of 2.45 eV. Photoluminescence results revealed that more stoichiometric thin films were formed after Dy-incorporations. The outcomes of the electrical investigation evidenced that the best sample was 1 at.% Dy-doped CdS thin films since the lowest resistivity (6.35 × 103 Ω cm) and highest carrier concentration (1.06 × 1014 cm−3) were obtained for this specimen.

Role of Sm dopant on structural, optical and efficient visible light photocatalytic performance of CdS nanoparticles by using simple wet chemical route

The present work reported the samarium (Sm) doped CdS nanostructures synthesized via using co-precipitation method from cadmium and sulphide particle arrangements with no ligands at different temperature arrangement and amalgamation time. Structural, compositional, valance state and optical properties of the prepared samples were investigated using X-ray powder diffraction (XRD), transmission electron microscope (TEM/EDS mapping), X-ray photoelectron, Fourier transform infrared red, UV–Vis absorption and photoluminescence spectroscopes. XRD and TEM results suggest that Sm doped CdS samples were cubic structure with spherical shaped morphology with average diameter of around 14–28 nm. The prepared Sm doped CdS nanoparticles showed the superior photocatalytic activity for the degradation of RhB under visible light (λ > 420 nm) irradiation, and 15 mol% Sm-doped CdS was found to be highly efficient for organic pollutants RhB and MB removal. Moreover, this catalyst showed improved stability, and the activity did not decrease significantly after seven recycles. This could be attributed to creation of electron–hole pairs and inhibit their recombination process by Sm doping. The improved mechanism by Sm doping is also discussed in detail.

Sm-doped CdS thin films prepared by spray pyrolysis: a structural, optical, and electrical examination

Virgin and Sm-doped CdS thin films were prepared by spray pyrolysis route on glass substrates. The influences of Sm-doping amount on structural, topographical, optical and electrical properties were examined. It was found from X-ray diffraction data that virgin and 1 and 2 at.% Sm-doped CdS samples grew along (002) plane whereas the preferred orientation changed to (101) starting from Sm doping of 3 at.%. Morphological investigation showed that even though CdS specimen had irregular shaped grains, Sm-doping substantially modified the surface topography of CdS thin films. A maximum transmittance were attained for 4 at.% Sm-doped CdS sample. After Sm-doping, a slight increase was observed in the band gap value of CdS thin films. It was found from the room temperature photoluminescence data that compared to the virgin CdS, the intrinsic defect population of Sm-doped CdS thin films reduced, meaning that more stoichiometric films formed. From the electrical measurements, it was determined that 1 at.% Sm-doped CdS thin films exhibited the best electrical properties, i.e., maximum carrier density and minimum resistivity. Based on all the data, it could be pronounced that 4 at.% Sm-doped CdS displayed the best optical properties, whereas the optimum electrical characteristics were reached for 1 at.% Sm-doped CdS thin films.

2262 Is less more? Examining the relationship between food assistance generosity and childhood obesity

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