Comparative study on the effect of precursors on the morphology and electronic properties of CdS nanoparticles (original) (raw)
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Polyhedron, 2009
Heterocyclic cadmium dithiocarbamates, [Cd(S2CNC5H10)2] and [Cd(S2CNC9H10)2] were synthesized. The complexes were thermolysed in hexadecylamine (HDA) to give HDA capped CdS nanoparticles. A combination of close to spherical, rod, bipods and tripods was obtained by varying the reaction parameters such as precursor concentration and temperature. The optical properties and X-ray diffraction studies of the particles are also reported.Heterocyclic cadmium dithiocarbamates, [Cd(S2CNC5H10)2] and [Cd(S2CNC9H10)2] were synthesized. The complexes were thermolysed in hexadecylamine (HDA) to give HDA capped CdS nanoparticles. A combination of close to spherical, rod, bipods and tripods was obtained by varying the reaction parameters such as precursor concentration and temperature. The optical properties and X-ray diffraction studies of the particles are also reported.
Effect of some nitrogen donor ligands on the optical and structural properties of CdS nanoparticles
New Journal of Chemistry, 2013
ABSTRACT The cadmium complex of N-ethyl-N-phenyl dithiocarbamate, 1, and its 2,20-bipyridine and 1,10-phenanthroline adducts, 2, and 3, respectively, have been used as single source precursors for the synthesis of CdS nanoparticles. The formation of CdS nanoparticles was achieved by thermal decomposition of the complexes (pyrolysis) and thermolysis in the presence of hexadecylamine – HDA (solvothermal). Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and high resolution transmission electron microscopy (HRTEM) analyses were carried out to study the structural properties of the nanoparticles. Complex 1 afforded rod-shaped nanoparticles while star-shaped nanoparticles were obtained from complexes 2 and 3. The optical property of the CdS nanoparticles was studied by UV–visible and fluorescence spectroscopy. The spectral features for the nanoparticles prepared via the solvothermal route were significantly sharper and blue shifted to a greater extent relative to the corresponding bulk semiconductor, compared to the observed shift in the nanoparticles prepared via pyrolysis. All the as-synthesized material exhibited band edge luminescence
Polyhedron, 2013
Bis(dipiperidinyldithiocarbamato)cadmium(II) (1) and bis(ditetrahydroquinolinyldithio-carbamato)cadmium(II) (2) were used as precursors for the synthesis of oleylamine (OA), decylamine (DA) and dodecylamine (DDA) capped CdS nanoparticles. The optical properties of these particles have been studied. The absorption spectra for the amine capped CdS particles are blue shifted in relation to the bulk material. The corresponding photoluminescence spectra show a narrow band edge emission. High quality crystalline CdS particles of different shapes, ranging from short nanorods and elongated nanorods (rods, bipods, tripods and tetrapods) to nanocubes were obtained when the reaction temperature was varied between 180 and 270°C. A decrease in the length of the rods and bipodal nanoparticles was observed with an increase in the length of the chain of the amine (capping agent) used. The p-XRD patterns revealed the hexagonal phase of CdS to be dominant in all the samples. Infra-red studies suggest that the mode of bonding of the amines (oleylamine, decylamine and dodecylamine) on the CdS nanoparticle surfaces is through electron donation from the nitrogen atoms.
South African Journal of Science, 2010
A single-source precursor route has been explored by using the diphenylthiourea cadmium complex as the source of cadmium sulphide (CdS) nanoparticles. The reaction was carried out using hexadecylamine (HDA) as the solvent and stabilising agent for the particles. The phenylthiourea complex was synthesised and characterised by means of a combination of spectroscopic techniques, microanalysis and X-ray crystal structural analysis. The diphenylthiourea complex was thermolysed in HDA at 120 °C for 1 h to produce CdS nanoparticles. The CdS nanoparticles prepared were made water-soluble via a ligand exchange reaction involving the use of pyridine to displace HDA. The pyridine was, in turn, replaced by glucose and glucuronic acid. The absorption and emission spectra showed the typical features of quantum confinement for the nanoparticles for both HDA-capped and glucose-or glucuronic acid-capped CdS nanoparticles. The change in the capping groups, from HDA to glucose and glucuronic acid, resulted in absorption and emission features that were almost similar, with only slight red-shifting and tailing. http://www.sajs.co.za
A facile route for preparation of CdS nanoparticles
2007
CdS nanoparticles have been synthesized by a chemical reaction route using ethylenediamine as a complexing agent. The nanoparticles were characterized using techniques such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), UV-VIS absorption spectroscopy, and photoluminescence spectroscopy. The absorption edge for the bulk hexagonal CdS is at 512 nm (2.42 eV). Comparing with the bulk CdS, it is believed that the blue shift in the absorption peak was caused by the quantum confinement effect. Photoluminescence measurements indicate CdS nanoparticles show fluorescence band with a maximum close to 315 nm.
Russian Journal of Inorganic Chemistry, 2019
Cadmium sulfide (CdS) nanoparticles have been synthesized from CdX 2 (X = Cl-, I-) complexes of 4-chlorobenzaldehyde and benzophenone thiosemicarbazone. The complexes have been studied by thermogravimetric analysis (TGA), elemental analysis, FT-IR, and NMR spectroscopy. The solvothermal decomposition of the complexes has afforded oleylamine-capped CdS nanoparticles with a wurtzite hexagonal phase. The transmission electron microscopy (TEM) studies show different morphologies which are influenced by reaction temperature and the nature of the ligands on the precursor complexes. Particles in the form of irregular cubes, elongated cubes and nanodendrites have been observed. The UV-Vis spectroscopy measurements show temperature and nature of complex-dependant optical properties. Blue-shifted band gap energies have been observed at lower reaction temperatures.
Chemistry of …, 2009
The reactions of cadmium acetate with picolinic (Hpic), 2,6-dipicolinic (H(2)Pydc), or salicylic acid (H(2)Sal) followed by the addition of thiourea (tu) or thiosemicarbazide (ths) yielded six new coordination complexes, including [Cd(Hsal)(2)(tu)(2)] (1a), [Cd(Pic)(2)(tu)(2)]center dot 0.5H(2)O (2a), [Cd(pic)(2)(ths)(2)]center dot 2H(2)O (2b), [Cd(pydc)(tu)(2)](3a), and [Cd(pydc)(ths)(2)(H(2)O)]center dot 2H(2)O (3b). All of the compounds were characterized spectroscopically and by elemental analysis. Compounds la, 2a, 2b, 3a, and 3b formed well-defined crystals and were further characterized by single-crystal X-ray diffraction. Additionally, reaction of Cd(Hsal)(2) with ths produced a compound 1b of uncertain composition that had bound ths as evidenced by ESI-MS. The most likely formula for this compound was Cd(sal)(ths)(x) but Cd(Hsal)(2)(ths)(x) was also possible. In compounds la and 3a, the Cd(II) ion exhibits penta-coordinated geometry; in la, three carboxylate oxygen atoms and two sulfur atoms from thiourea complete the coordination sphere, whereas in 3a, two carboxylate oxygen atoms, one pyridyl nitrogen atom and two sulfur atoms from thiourea are within the coordination sphere. In 2a and 2b, the Cd(II) ions are hexa-coordinated, binding to two carboxyl oxygen atoms, two pyridyl nitrogen atoms, and two sulfur atoms in both cases. In 3b, the thiosemicarbazide acts as a chelating ligand, coordinating through both the sulfur atom and the primary nitrogen atom of NHNH(2) group. In addition, two carboxylate oxygen atoms, one pyridyl nitrogen atom, and one water molecule are within the coordination sphere making the central Cd(II) ion hepta-coordinated. Although the complexes appeared to be slightly photosensitive they are stable under ambient conditions. The precursors were decomposed at 175 degrees C using N-cetyl trimethylammonium bromide, ethylenediamine, oleylamine, or hexadecylamine as surfactants. The US nanoparticles were explored by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), and energy-dispersive spectroscopy (EDS). Solvothermal decompositions using CTAB in an aqueous solution gave rise to microsized flowerlike crystals; long-chain organic amines such as oleylamine or hexadecylamine led to spherical or ellipsoidal nanoparticles, ethylenediamine produced nanorods, and a mixed surfactant of tri-n-octylphosphine and oleylamine produced multipod structures. TEM studies revealed planar defects (such as poly-synthetic and multiplet twinning) in the nanocrystals, which gives an explanation for mechanism of growth. Interestingly, linear arms that arise from polypodal branching may not necessarily be a single phase. Even straight arms may exhibit highly regular polysynthetic twinning. From XRPD studies, it was found that most of the nanostructures were of the stable hexagonal phase. However, in two cases, the nanostructures were found to be predominantly of a metastable orthorhombic phase. Variation of precursor slightly affected the morphology of the decomposition product.
N-alkylthioureacadmium (II) complexes as novel precursors for the synthesis of CdS nanoparticles
Journal of Materials Science: Materials in Electronics, 2000
The cadmium(II) complexes of thiourea and N-alkylthioureas (with alkyl group methyl or ethyl) have been used as precursors for the preparation of TOPO-capped CdS nanoparticles. The precursors are air-stable, easy to prepare and inexpensive. These compounds decompose cleanly to give good quality crystalline materials. The nanoparticles obtained showed quantum con®nement effects in their optical spectra and close-to-band-edge emission in luminescence experiments. The broad diffraction patterns and the diffuse rings observed in the SAED patterns are typical of nanometric particles. The TEM images showed agglomerates of needle-like plates of particles. The presence of a strong phosphorus peak in the EDAX spectra is indicative of TOPO bound to the surface.
Surface and Interface Analysis, 2019
We report on the successful synthesis of CdSe nanoparticles (NPs) via a facile aqueous approach. Investigation on the effects of various cadmium sources in the precursor solution on the CdSe NPs is discussed. The structural and morphological properties characterized by the X-ray diffraction (XRD) and scanning electron microscope (SEM) displayed good features of the as-prepared CdSe NPs. The XRD pattern displayed a pure zinc blende crystal structure for all samples, with the most crystalline sample observed for CdSe NPs prepared using anhydrous cadmium chloride. The estimated crystallite sizes were below 6 nm for all the CdSe NPs samples. Mixed shapes of spherical and nanorods of varying sizes were observed from the SEM images for the as-prepared NPs prepared using different cadmium sources. The optical studies conducted by photo-spectroscopy pointed out the CdSe NPs prepared using anhydrous cadmium chloride gave the best optical properties. The emission wavelengths were in the range 565 to 574 nm while the optical band gaps were in the range 2.94 to 3.23 eV for all the as-prepared CdSe NPs samples. All the samples, however, displayed quantum confinement effects giving room for further fabrication and engineering to suit specific applications in the biological field. The obtained results demonstrated that aqueous phase synthetic route employed in this study could be successfully adopted for production of high-quality CdSe NPs because of its facile and inexpensive nature.