Presence Of CdS Nanoparticles Research Articles

Preparation of Cadmium Sulfide/Polystyrene Nanocomposites Films Using Gamma Irradiation

In the present study we have synthesized Cadmium Sulfide/Cetyltrimethylammonium bromide (CdS/CTAB) nanoparticles + by the gamma ray irradiation method and then embedded in polystyrene polymer with different concentration (2, 5 and 10 wt%) forming CdS/PS nanocomposites using solution casting method. The as-prepared CdS/CTAB nanoparticles and CdS/PS nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), Ultraviolet/Visible (UV/Vis) absorption, high resolution scanning electron microscopy (HRSEM) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase. FTIR data suggesting interaction of the alkyl ammonium head group of CTAB with the CdS nanoparticle surface. UV–Vis spectroscopy revealed that the CdS/PS nanocomposites films showed quantum confinement effect. The TGA results showed incorporation of CdS nanoparticles significantly enhance the thermal properties of PS matrix. The photoluminescence spectra of CdS/PS nanocomposites films show two emission bands arising from the presence of CdS nanoparticles.

Biosynthesis of CdS nanoparticles: A fluorescent sensor for sulfate-reducing bacteria detection

CdS nanoparticles were synthesized with an environmentally friendly method by taking advantage of the characteristic metabolic process of sulfate-reducing bacteria (SRB), and used as fluorescence labels for SRB detection. The presence of CdS nanoparticles was observed within and immediately surrounded bacterial cells, indicating CdS nanoparticles were synthesized both intracellularly and extracellularly. Moreover, fluorescent properties of microbial synthesized CdS nanoparticles were evaluated for SRB detection, and a linear relationship between fluorescence intensity and the logarithm of bacterial concentration was obtained in the range of from 1.0×102 to 1.0×107cfumL−1. The proposed SRB detection method avoided the use of biological bio-recognition elements which are easy to lose their specific recognizing abilities, and the bacterial detection time was greatly shortened compared with the widely used MPN method which would take up to 15 days to accomplish the detection process.

Influence of Mn-doping with CdS on the structural and optical properties of ZnS/CdS/TiO2 photoanodes

In the present work, Mn-doped semiconductor sensitized photoanodes were prepared by spin coating followed by successive ionic layer adsorption and reaction method. The structure and morphology of Mn-doped anodes were investigated by XRD, Raman, SEM with EDX and TEM analysis. These analyses depict the enabled presence of CdS nanoparticles into the nanoporous TiO2 structure. The calculated crystallite size of Mn-doped CdS nanocrystals is found to be 2 nm from XRD pattern. The optical absorption results reveal that Mn-doping with CdS could greatly enhance the absorption of TiO2 in the visible region, leading to a decrease in the bandgap energy from 3.43 to 2.02 eV. Photoluminescence (PL) spectrum shows two strong emission peaks one at near UV (367 nm) and the other at violet region (411 nm) with an additional low intensity red emission peak at 633 nm due to oxygen vacancies and defects. On comparing with undoped CdS film, PL spectra suggest that all the emission peaks are slightly blue shifted for the Mn-doped film (ZnS/Mn–CdS/TiO2). It has been demonstrated that the doping of Mn with CdS on the surface of the TiO2 nanostructured film could improve the electrical performance of the anode through rapid electron transport by enhanced absorption of the incident light.

Synthesis and characterization of organic–inorganic hybrid materials prepared by sol–gel and containing CdS nanoparticles prepared by a colloidal method using poly(N-vinyl-2-pyrrolidone)

This paper describes the synthesis and characterization of CdS nanoparticles (NPs) stabilized with poly(N-vinyl-2-pyrrolidone) and their further immobilization on a hybrid organic–inorganic matrix produced by the sol–gel process. The production of the hybrid matrix doped with CdS NPs was carried out in two steps. In the first step a precursor, designated diureasil precursor, was synthesized from the reaction between the terminal amine groups of α,ω-diamine-poly(oxyethylene-co-oxypropylene) and the isocyanate group of 3-isocyanatopropyltriethoxysilane. The next step involved the hydrolysis and condensation reactions of ethoxy groups attached to silicon, this step resulting in the formation of a crosslinked siliceous network linked through urea bonds to a poly(oxyethylene)/poly(oxypropylene) chain. The NPs were added to the diureasil precursor before the gelation process to allow a homogeneous dispersion of the NPs within the matrix. The developed method allowed the transfer of colloidal NPs to a solid matrix without the need of exchange the capping agents or the solvent. The materials were characterized by absorption, steady-state photoluminescence spectroscopy and by TEM. The results obtained showed the presence of CdS NPs with quantum size effect dispersed within the diureasil matrix. The obtained nanocomposites show a high transparency in the visible range accounting for the good dispersion of the NPs within the matrix. The TEM analysis confirmed that the NPs are uniformly dispersed within the diureasil matrix.

Synthesis, characterisation and adsorption/photocatalytic performance of ZnO/CdS flowers

A ZnO/CdS composite with flower-like morphology was fabricated by combining a solvothermal route with a homogeneous precipitation process. The material characterisation showed that the composite was composed of hexagonal ZnO flowers and cubic CdS nanoparticles, and CdS nanoparticles were observed to assemble on the surface of the ZnO flowers. The presence of CdS nanoparticles on the surface of ZnO flowers resulted in a blue shift of characteristic peaks and decreasing of the photoluminescence intensity when compared with the ZnO flowers. Furthermore, the adsorption or photocatalytic degradation experiments indicated that the as-prepared ZnO/CdS composite exhibited superior adsorption or photocatalytic degradation activities for some organic dyes, such as methyl orange, rhodamine B, safranine T and methylene blue, which may be related to the modification of the CdS nanoparticles.

Single-source precursor approach for the preparation of CdS nanoparticles and their photocatalytic and intrinsic peroxidase like activity

CdS nanoparticles (NPs) with different shapes and sizes (rods and spheres) have been synthesized through decomposition of a newly synthesized precursor complex [Cd(SOCPh)2Lut2] using structure-directing solvents such as ethylenediamine (EN), dimethylsulfoxide (DMSO) and ammonia (NH3). In addition, CdS NPs is also prepared by thermal decomposition of the precursor complex under N2 atmosphere. The precursor complex is characterized by elemental analyses, TGA, FTIR, UV–vis spectroscopy and single crystal X-ray diffraction. The distorted tetrahedron geometry of the precursor complex has been determined by X-ray diffraction, which crystallizes in monoclinic crystal system of P2(1)/n space group with a=11.0487(17)Å, b=16.396(3), c=15.413(2)Å, α=90.00°, β=109.708(4)°, γ=90.00° and Z=4. The CdS NPs are characterized using powder X-ray diffraction, transmission electron microscopy, BET analyses, UV–vis absorption and photoluminescence spectroscopy. The photo-catalytic activity of CdS NPs is studied by the degradation of Rose Bengal (RB) dye, indicating an excellent photocatalytic activity compared to that of commercial TiO2. The mechanism behind photocatalytic degradation of RB in presence of CdS NPs is elucidated using terephthalic acid photoluminescence probing technique and evidence have shown that the photogenerated holes to be the predominant active species. This paper also demonstrates the intrinsic peroxidase like activity of CdS NPs toward peroxidase substrates 3,3′,5,5′-tetramethyl benzidine (TMB) and hydrogen peroxide. Kinetic analysis indicates that the catalysis by CdS NPs show typical Michaelis–Menten kinetics. Moreover, our synthesized CdS NPs show higher catalytic performances with a higher binding affinity for the substrate TMB than horseradish peroxidase (HRP) and other recently reported nano-mimitics.

Effect of alcohol and alcohol/water mixtures on crystalline structure of CdS nanoparticles

A simple approach is discussed to synthesise CdS nanoparticles using various pure alcohols and their mixtures with water as a reaction medium. The study highlights that the solvent plays an effective role not only in controlling the particle size but also the structure. The size and phase of CdS nanoparticles were controlled by thermal reaction between cadmium precursor and thiourea in alcohol and their mixtures with water. Use of pure alcohols for the synthesis produces cubic structure as revealed from X-ray diffraction (XRD), while mixture of water with alcohol gives rise to hexagonal phase. XRD showed the presence of CdS nanoparticles with size 10–13 nm in an alcohol–water mixture whereas use of alcohols alone showed size in the range 1–3 nm. The composition and structural features were also studied by Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Thiourea, in the presence of pure alcohol seems to be responsible for reduction in particle size as compared to that in the presence of alcohol/water mixture. The possible mechanism for the structural phase transition is discussed on the basis of change in surface energy and solvent–solvent interaction.

Exceptional catalytic efficiency in mineralization of the reactive textile azo dye (RB5) by a combination of ultrasound and core–shell nanoparticles (CdS/TiO 2)

A novel composite with a core–shell structure (CdS/TiO 2) was prepared through the combination of microemulsion and ultrasound (20 kHz). The degradation of reactive black 5 (RB5) was carried out in aqueous solution in a series of experiments by CdS/TiO 2 nanoparticles. This composite with mole ratio of 1/6 has shown an exceptional sonocatalytic activity in comparison to the pure nanoparticles of TiO 2 and CdS. A significant decrease in the concentration of RB5 (≈94%) was observed in 3 min sonication of the solution containing the core–shell nanocomposite. While at the same time, the concentration was reduced to 4% under sonication without nanocomposite and 50% under UV light with nanocomposite. The increased catalytic activity of nanocomposite in the presence of ultrasound is due to the enhancement of mass transfer, cleaning and sweeping the surface of catalyst, and preventing the aggregation of particles. In addition, the presence of CdS nanoparticles in the composite acts as photosensitizer which not only extends the spectral response to the visible region but also reduces the charge recombination. The selected combined method (sonocatalysis) was able to decolorize and oxidize simultaneously the organic dye with a complete mineralization into SO 4 2− and NO 3 − ions.

Effect of CdS nanoparticles on photoluminescence spectra of Tb3 + in sol–gel-derived silica glasses

CdS nanoparticles doped with Tb3 + were synthesized by sol–gel technique. The influence of CdS on the Tb3 + glass was studied by UV-Visible and luminescence spectroscopy. The luminescence intensity of the glasses increased significantly in the presence of CdS nanoparticles. Terbium ions excited into the 5 D 3 level have a rich emission spectrum in the 400–700 nm range decaying to different 7 F J levels. The intensity of violet and blue luminescence from 5 D 3 level is highly dependent on Tb3 + concentration, on presence of CdS co-dopant and annealing conditions.

Effect of CdS nanoparticles on fluorescence from Sm3+ doped SiO2 glass

Sm3+ doped CdS nanoparticles have been prepared by sol–gel method. The effect of annealing temperatures and doping concentrations of CdS on the photoluminescence spectra of Sm3+ were studied. From the measurement of its optical absorption, three phenomenological Judd–Ofelt intensity parameters (Ω2, Ω4, and Ω6) have been computed and used to parameterize the radiative properties. The influences of CdS on Sm3+ ions were studied by fluorescence spectroscopy. The fluorescence spectra revealed that the emission intensity of samarium increased considerably in the presence of CdS nanoparticles. The evaluation of radiative properties of Sm3+ containing CdS showed that the 4G5/2→6H7/2 transition in silica matrix had the potential to be a laser transition.

Preparation and electrochemical behaviour of PPy–CdS composite films

PPy/CdS composite films made from polypyrrole (PPy) with embedded semiconductor (CdS) quantum dots were obtained by electropolymerization of pyrrole in the presence the CdS nanoparticles dispersed in the electrolytic aqueous solution. For the characterization of the modified surface electrode by PPy–CdS, the scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–visible were used. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been used to investigate the electrochemical behaviour of the resulting materials. The illumination effects are also observed in the reduced form of the polymer. This study showed that the presence of CdS nanoparticles in the polypyrrole film improves the optical properties of PPy via a simple preparation method and show that these films have potential in the photoelectrochemical applications such as photovoltaic cells.

Fluorescence Enhancement in Tb3+/CdS Nanoparticles Doped Silica Xerogels

Cadmium sulfide semiconductor nanoparticles along with terbium ions were incorporated in silica xerogels through sol-gel route. The optical absorption and emission spectra confirmed the formation of CdS nanoparticles along with terbium ions in the silica gel. The optical bandgap and size of the CdS nanoparticle were calculated from the absorption spectrum. The TEM measurement was also used to evaluate the average size of the CdS nanoparticles. The fluorescence spectra reveal that the intensity of characteristic emission of terbium ions increases considerably in the presence of CdS nanoparticles even in the gel stage itself and this avoids the need of heating gels at high temperatures. The branching ratios were calculated from the emission spectra using the standard procedure.

Composites comprising CdS nanoparticles and poly(ethylene oxide): optical properties and influence of the nanofiller content on the thermal behaviour of the host matrix

Tri-n-octylphosphine oxide-capped CdS nanoparticles were synthesized with the cadmium(II) complex of thiocarbohydrazide as a precursor. Nanocomposites were prepared by mixing a toluene solution of poly(ethylene oxide) (PEO) and the obtained CdS nanoparticles. The ultraviolet-visible spectroscopy measurements showed a blue shift of the onset of optical absorption, compared to bulk CdS, which confirmed the presence of nanostructured CdS. A transmission electron microscopy micrograph of the nanocomposite depicted that the nanoparticles are well dispersed in the PEO matrix. Differential scanning calorimetry analysis revealed hindered crystallization of PEO in the presence of CdS nanoparticles. It was also found that increasing the nanoparticle content led to the shift of the onset of decomposition of the matrix towards higher temperature.

Tribology Properties of CdS Nanoparticles In Situ Synthesized in Lamellar Liquid Crystal System of Triton X‐100/C10H21OH/H2O

This article reports the lubrication of the mixed system of CdS nanoparticles and Triton X‐100/C10H21OH/H2O lamellar liquid crystals. CdS nanoparticles could be synthesized in the lamellar liquid crystal's solvent layer, limited by its amphiphile bilayer. The CdS nanoparticles were spherical and the size was about 5 nm. The lubrication properties of the mixed system of the lamellar liquid crystal and CdS nanoparticles were determined. The results showed that the presence of CdS nanoparticles could improve the antiwear ability and extreme pressure property of Triton X‐100/C10H21OH/H2O lamellar liquid crystals.

Cadmium Sulfide Nanoparticles in Langmuir−Blodgett Films of Calixarenes

CdS nanoparticles have been formed within Langmuir−Blodgett (LB) films of cadmium salts of calix[8]- and calix[4]arene by reaction with hydrogen sulfide gas. The presence of CdS nanoparticles in the LB film matrices was checked by measurement of UV−vis absorption spectra, which allows an estimation of the size of the particles. It was shown that smaller particles (1.5 ± 0.3 nm) are formed in calixarene LB films than in Cd stearate films (used for comparison). The particle size does not depend on the type of calixarene or the number of LB layers but increases with increasing pH of the subphase. The formation of CdS was directly confirmed with XPS.