Cadmium Sulfide Nanocrystallites Research Articles

Application of Copper doped Cadmium Sulphide Nanocrystallites for controlling Oral Pathogen activity

In this study, we tend to incontestable the synthesis and antimicrobial action of Copper doped Cadmium Sulphide nanomaterials averse oral pathogens.Using Chemical Co-Precipitation method, Copper doped cadmium sulphide (Cu:CdS) nanomaterials are Synthesised. The sizes of the samples prepared are found by XRD (x-ray diffraction) method. SEM (scanning electron microscopy carried out to find the Morphological analysis. Materials present are confirmed by EDAX (energy dispersive analysis of x-ray spectroscopy) method. The outcomes showed that the proteins, which contain amine gatherings, played a diminishing and controlling obligation during the arrangement of Copper doped cadmium sulphide (Cu:CdS) nanomaterials in the colloidal arrangement. The antimicrobial action was evaluated against oral pathogens, for example, Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Escherichia coli, Proteus vulgaris and Shigella flexneri and these outcomes affirmed that the Copper doped Cadmium sulphide nanomaterials are showing great bactericial action.

Femtosecond laser stimulated anisotropy of electrolytically produced CdS polymer nancomposites

Studies of two-beam coherent induced optical anisotropy has been performed for the cadmium sulphide nanocrystallites (NC) embedded within the different polymer matrices. The NC were fabricated by the modified electrolytical method and have been embedded into different polymer matrices: PC, PMMA, PVA. The phototreatement was performed by two space split coherent beams generated by 120 fs laser with pulse energy 23 nJ. The phototreatment has been durated several minutes until the clear diffraction grating has been observed. The monitoring of the laser induced gratings and of the anisotropy was performed using the cw 1150 nm continuous wave He–Ne laser with power about 30 mW. Varying the polarization of the laser coherent femtosecond beams we have found that the optimal gratings has been achieved for 45° polarizations between the beams. The control of the maximal laser induced gratings has been done using optically polarized method. The effect is not completely reversible and there remain some changes after switching off of the phototreatment. The anisotropy has been monitored by Senarmont method. The role of different polymers on the output photo stimulated birefringence was explored. This method may be promising for the design and engineering of optical triggers in the femtosecond laser pulse duration.

Cadmium Sulphide Nanocrystallites for Optoelectronic Devices

Cadmium sulphide nanocrystallites have been synthesized using precipitation method. The average sizes of the prepared samples is determined by XRD (x-ray diffraction) method. Morphological studies are carried out by SEM (scanning electron microscopy) measurement. Necesssary elements present in prepared samples, are confirmed by EDAX (energy dispersive analysis of x-ray spectroscopy) method. By Ultraviolet visible spectroscopy measurement, the value of absorption wavelength, band gap values are calculated in optical method. The electrical properties are analysed using impedance analyser measurement for the Nanocrystallites.

Synthesis, Structural Analysis of Cadmium Sulphide Nanocrystallites

In this paper, the effect of size variation of cadmium sulphide nanocrystallites which have been prepared by precipitation method is analyzed. These prepared samples were studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive analysis of spectroscopy (EDAX) techniques. SEM analysis represents the morphological nature of prepared samples and EDAX indicates the confirmation of elements present in the sample. XRD analysis determines the size of the samples and identifies the structure using miller indices (h k l values) of the nanocrystallies matches with JCPDS. From the XRD analysis, the size variation which depends on dopant, capping agent are discussed and corresponding results are reported in this paper.

Advancement in Photothermal Effect of Carbon Nanotubes by Grafting of Poly(amidoamine) and Deposition of CdS Nanocrystallites.

A robust, near-infrared (NIR) active photothermal agent, CNTs-PAMAM/G4-CdS, is designed by covalent grafting of fourth generation poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of cadmium sulfide (CdS) nanocrystallites. The systematic advancement in photothermal effect of CNTs was achieved by grafting of first, second, third, and fourth generation PAMAM through the repeated process of Michael's addition. The subsequent deposition of CdS nanocrystallites over fourth generation PAMAM grafted CNTs has further improved the photothermal effect (PTE) of CNTs. The photothermal effect of CNTs-PAMAM/G4-CdS was accessed by illuminating with 980 nm NIR laser. During measurement of PTE, maximum temperature attained by CNTs-PAMAM/G4-CdS was 64.1 °C which far exceeds the survival temperature of cancer cells. The photothermal conversion efficiency estimated for CNTs-PAMAM/G4-CdS was 32%, which is higher than the value reported for popular gold and copper based photothermal agents. Apart from its outstanding photothermal effect, CNTs-PAMAM/G4-CdS possessed excellence in both antiphoto-bleaching and antiphoto-corrosiveness.

Operation by optoelectronic features of cadmium sulphide nanocrystallites embedded into the photopolymer polyvinyl alcohol matrices

Laser operation by optical third harmonic generation at Er:Yb glass laser fundamental wavelength 1540 nm for the cadmium sulphide (CdS) nanocrystallites (NC) with average sizes 13 nm, 20 nm, 50 nm embedded into the poly(vinyl alcohol) (PVA) photopolymer matrices was discovered. The 300 mJ intensity modulated continuous wave (cw) Nd:YAG 1060 nm laser was used for photoinduced changes. The content of CdS NC was chosen to be 3%, 6%, 9%, 12%. The CdS NC have been synthesized using electrolytic procedure and their structural and morphological features were monitored by X-ray diffraction and transmission electron microscopy (TEM). The dependences of the THG versus the cw laser light power density at 1060 nm was studied and has shown an existence of the maxima which are strongly dependent on the NC sizes. Generally with decreasing NC sizes the laser stimulated THG was increased. The relaxation of the photoinduced changes was explored. The effect may be used for laser operation by coherent harmonic generation in the CdS/polymer nanocomposites.

Structural Properties of Size Variation of Nanocrystallites

Silver doped cadmium sulphide nanocrystallites (CdS:Ag), undoped cadmium sulphide nanocrystallites (CdS), have been synthesized by the chemical precipitation method. Nanocrystalline materials are confirmed by the scanning electron microscopy method. The presented elements are identified by EDAX (Energy Dispersive X-ray Analysis). X-ray diffraction Method (XRD) is used to calculate the average size of the prepared sample. Morphological studies (SEM) are used to analyse the nature of the sample. The results are reported in this paper.

Free-standing nanocrystalline-Cadmium sulfide/Polyvinylidene fluoride composite thin film: synthesis and characterization

Nanocrystalline Cadmium sulfide (CdS) impregnated polyvinylidene fluoride (PVDF) composite free-standing flexible films were prepared by sol–gel technique. The films were poled in vacuum under high electric field. Effect of CdS loading in PVDF host matrix on the optical properties was studied critically for the as-deposited and poled samples. The reduction in the relative intensities of the peaks arising out of α -PVDF as compared to that of β-PVDF for the poled samples was observed in X-ray diffraction (XRD) studies. This type of observation indicates a possible transition from α to β phase due to poling. Modulation of optical and microstructural properties with CdS loading was also addressed. Bonding environment was studied by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy measurements. XPS studies indicated the presence of highly aligned CdS nanocrystallites in the poled PVDF matrix which may effectively modulate the piezoelectric behavior of the composite film. The Photoluminescence (PL) spectra recorded as above for a representative unpoled and poled nano-CdS/PVDF composite film.

The Synthesis and Characterization of Novel Cadmium Sulphide Nanocrystallites and their Thin Films

Diethyl dithiocarbamate [Cd (S2CN Et2)2] complex is used to deposit the cadmium sulphide thin film at much lower temperature by Aerosol Assisted Chemical Vapour deposition (AACVD) and same precursor is used to synthesize the nanocrystals in Oleylamine at elevated temperature. Thermogravimetric analysis shows that precursor [Cd (S2CN Et2)2] decomposes in the single stage, losing 62% of total weight. Deposition of thin films at 300 °C and 400 °C showed the growth of CdS clusters which were made of granular crystallites. These results are confirmed by SEM analysis. Thermolysis of the precursor in oleylamine at 240 °C gave the nanoparticles most of them are monodispersed spherical shape, few having mono and dipod structures. TEM images confirm the structures. XRD results show the thin films and nanoparticles have hexagonal phase of CdS.

SYNTHESIS AND CHARACTERIZATION OF CdS NANOCRYSTALLITES DISPERSED IN POLYMER MATRIX

Cadmium sulphide (CdS) nanocrystallites were prepared by sulphuration route with capping in polyethylene oxide (PEO) polymer matrix. It is found that PEO could provide a confined environment for particle nucleation and growth of CdS nanocrystallites. The scanning electron microscopy (SEM) with energy dispersive analysis by X-ray (EDAX) studies confirms the presence of CdS nanocrystallites in polymer matrix. X-ray diffraction (XRD) studies and transmission electron microscopy (TEM) selected area diffraction (SAD) patterns show that these crystallites have hexagonal structure. The TEM and UV-Visible absorption studies indicate uniform size distribution having size around 2.3 nm and band gap of 2.7 eV. X-ray photoelectron spectroscopy (XPS) studies reveal that core level energy positions of the Cd is shifted towards the lower binding energy and has similar chemical environment to that of bulk CdS .

Synthesis of thiol capped CdS nanocrystallites using microwave irradiation and studies on their steady state and time resolved photoluminescence

Synthesis of cadmium sulfide (CdS) nanocrystallites has been performed through the microwave (MW) assisted reaction of cadmium acetate with thiourea in N,N-dimethylformamide (DMF) in the presence of two capping agents, 1-butanethiol and 2-mercaptoethanol. Attempts were made to control the size and size distribution of the thiol capped CdS nanocrystallites by controlling the number of MW irradiations/exposures for a fixed time (duration). The prepared nanocrystallites have been characterized by UV-vis spectroscopy, FTIR, XRD, FESEM and TEM. The peak position of the absorption band of the 1-butanethiol caped CdS nanocrystals in DMF solution shifted towards longer wavelength with the increasing number of MW exposures indicating the growth of particle size. In contrast, the peak position of absorption band for the 2-mercaptoethanol capped CdS nanocrystals remained nearly at the same wavelength and only the intensity of the absorption band increased with the increasing number of MW exposures. The observed steady state photoluminescence (visible range) of the 1-butanethiol capped CdS nanocrystals in DMF solution shifted towards higher wavelength, showing a decrease in intensity, with the increase in the number of MW exposures. Whereas in the case of 2-mercaptoethanol capped CdS nanocrystals in DMF solution, the photoluminescence peak remained nearly at the same position showing a decrease in intensity with increase in the number of MW exposures. The interesting results on the size-dependent steady state and time resolved photoluminescence (PL) of the CdS nanocrystallites are discussed in the present article. Possible application of such studies in the area of biotechnology has been mentioned.

A novel femtosecond-laser formation of CdS nanocrystallites in zirconia matrices

A novel method for direct laser writing of two-dimensional cadmium sulfide (CdS) semiconductor nanoparticle microstructures is reported. A two photon or a higher-order multiphoton absorption process, originating from femtosecond laser pulses, was used to decompose CdS precursors dispersed in a zirconia thin film previously dip-coated on a glass substrate. The kinetics of nanoparticle formation as a function of laser power were monitored in situ by photoluminescence spectroscopy. Raman spectroscopy was also performed to characterize the structural changes of the zirconia matrix under irradiation and to verify the formation of CdS nanoparticles. Results show that CdS nanoparticles were formed by two-photon absorption (TPA) with or without the help of an additional carbazole photoinitiator.

Inorganic surface passivation of CdS nanocrystals resulting in strong luminescence

Cadmium sulphide (CdS) nanocrystals have been synthesized by wet chemical route using cadmium chloride, thiourea and sodium hydroxide in ethanol solution. Triethylamine (TEA) is used as a capping agent. The products were characterized by high resolution transmission electron microscope (HRTEM), powder X-ray diffraction (XRD) pattern, UV–visible, FT-Raman, thermal and photoluminescence studies. The spherical morphology of the TEA capped CdS has been observed by TEM. Broadening of the XRD peaks and asymmetrical broadening of longitudinal optical (LO) modes in FT-Raman indicated the nanocrystal formation. Strong photoluminescence was observed in TEA capped nanocrystals. UV spectrum showed blue shift due to size quantization effect. The high temperature behavior of CdS nanocrystallites has been studied using thermal analyses.

Visible light-induced splitting of water using CdS nanocrystallites immobilized over water-repellant polymeric surface

The paper reports on a well dispersed cadmium sulfide (CdS) catalyst that exhibits high activity for visible light-driven hydrogen production from photocatalytic splitting of water, and at the same time maintains a significantly long active life because of its hydrophobic nature. The catalyst comprises of uniform CdS crystallites of 2–5 nm size, coated at loadings of 5–17 wt% over a polymeric support (polystyrene) having a rough and porous texture. The samples are characterized using the techniques of powder X-ray diffraction, UV–Visible spectroscopy, scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of this supported CdS catalyst, as well as that of an aqueous suspension of CdS powder, is monitored for the visible light-induced evolution of H 2 from water in the presence of hole scavengers S 2 - and SO 3 2 - . While the rate of hydrogen evolution was found to increase with loading, a reverse trend was observed for the amount of H 2 produced per unit mass of CdS. Furthermore, much smaller quantities of hydrogen were evolved under the identical test conditions when an equivalent amount of bulk CdS powder was directly suspended in water. These results clearly demonstrate the vital role played by the particle size and dispersion in the photocatalytic splitting of water for hydrogen generation. In the experiments conducted over the period of several days, with random breaks in photo-irradiation but no in-between catalyst activation, the evolution of hydrogen was found to stop at the stage when sacrificial agents S 2 - / SO 3 2 - were completely oxidized. The reaction was revived again when the aqueous solution was replaced by a fresh lot, though the progressively lower amounts of H 2 were produced in these repeated cycle experiments. It can therefore be concluded that the slow activity loss of CdS/polyester is related to the formation of S 2 O 6 2 - and/or SO 4 2 - species produced on photo-oxidation of the sacrificial agents, rather than to the degradation of the photocatalyst.

Synthesis of high-luminescent cadmium sulfide nanocrystallites by a novel single-source precursor route

Highly luminescent cadmium sulfide nanocrystallites have been successfully produced by the thermolysis of a novel single-source precursor, cadmium O, O′-dialkyldithiophosphates, which were dissolved in oleic amine. The microstructure and morphology of the as-prepared CdS nanoparticles were characterized using X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy. It was found that the as-prepared CdS nanoparticles show a narrow size distribution and high crystallinity. The optical properties of these samples were examined by UV–visible and photoluminescence spectroscopy. Not only an intensive red-light-emitting luminescence phenomenon derived from the solution of the CdS nanocrystallites can be observed easily at room temperature, the band gap of CdS nanocrystallites can also be tailored by changing the length of substituted alkyl chain of single-source precursors.

Study the Influence of Drying Control Chemical Additives on the Physical and Optical Properties of Nanocrystalline Cadmium Sulfide–Doped Tetraethylorthosilicate Silica Xerogels

The experimental results of the influence of drying control chemical additives (DCCAs)—such as formamide (FA), N-methyl formamide (NMF), N-N′-dimethyl formamide (DMF), acetamide (AA), glycerol (GLY), and oxalic acid (OXA)—on the physical and optical properties of nanocrystalline cadmium sulfide (CdS)–doped silica xerogels were reported in this paper. Tetraethylorthosilicate [TEOS, Si(OC2H5)4] was used as a precursor for the three-dimensional silica network in which the CdS nanocrystallites were trapped. Silica alcosol was prepared by taking the mixture of ethanolic (EtOH) TEOS, water (H2O), hydrochloric acid (HCI), and ammonium hydroxide (NH4OH). Ethanolic cadmium acetate [Cd(CH3COO)2 ⋅ 2H2O] and thiourea [CS(NH2)2] were added to the alcosol for the formation of CdS crystallites. To study the effect of DCCAs on the physical and optical properties of nanocrystalline CdS-doped silica xerogels, the molar ratio of TEOS:EtOH:H2O:HCl:NH4OH:Cd(CH3COO2)2 2H2O:CS(NH2)2 was kept constant at 1:5:7:0.01:0.0027:0.001:0.002, respectively, and the molar ratio of DCCA/TEOS was varied from 0.001 to 1. The addition of DCCAs (e.g., formamide) resulted in decreased gelation time (tg) from 240 to 0.5). It has been found that the percentage of volume shrinkage of the samples, when heated at 300°C for 3 hr, was more (>15%) for OXA, GLY, and DMF and the shrinkage was less (<15%) for AA, NMF, and FA. The density of the CdS-doped silica xerogels with DCCAs was less than that without DCCAs. Red shift was observed in the optical absorption spectra of the samples with addition of the DCCAs. An increase in CdS crystallite size in the silica matrix with the incorporation of DCCAs was observed in the X-ray diffraction patterns in the order: OXA < GLY < DMF < AA < NMF < FA. From XRD studies, the structure of the CdS crystallites in the silica matrix was found to be hexagonal wurtzite.

Preparation and characterization of nanocrystalline CdS doped monolithic and transparent TEOS silica xerogels using sol–gel method

Nanocrystalline cadmium sulfide (CdS) doped silica xerogels were prepared by hydrolysis and polycondensation of ethanol diluted tetraethoxysilane (TEOS) in the presence of HCl and NH 4OH medium using cadmium acetate [Cd(CH 3COO) 2] and thiourea [SC(NH 2) 2] as the reactants in the silica sol followed by drying and slow heating of the resulting gel to 300°C at atmospheric pressure. Monolithic and transparent CdS doped silica xerogels were obtained with HCl/TEOS and NH 4OH/TEOS molar ratios of 0.1 and 0.0027 respectively. By varying the molar ratios of Cd/Si from 0.0005 to 0.08, the colour of the xerogels changed from light yellow to brown indicating a change in the size of the CdS nanocrystallites. The CdS doped xerogels were characterized using UV–visible spectroscopy and X-ray diffraction (XRD) techniques. In the optical absorption spectra, the absorption edge exhibited a blue shift compared with that of the bulk CdS crystal. The absorption threshold peaks were measured from the UV–visible spectra for different Cd/Si molar ratios. It was found that with increasing Cd/Si; molar ratio the absorption threshold peak shifted towards higher wavelengths. The crystallite sizes were calculated from XRD patterns and using tight binding calculation method. The XRD patterns revealed that the CdS nanocrystallites structure was hexagonal wurtzite. It was found that the crystallite sizes varied from 1 to 5 nm depending on the Cd/Si molar ratios (more the ratio, bigger the sizes). Increase of alcogel ageing resulted in the increase of CdS nanocrystallite sizes.