The role of potassium tellurite as tellurium source in mercaptoacetic acid-capped CdTe nanoparticles

El-sadek, M.S. Abd; Kumar, J.; Babu, S. Moorthy

doi:10.1016/j.cap.2009.06.016

Cited by 29 publications

(11 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It was recently reported that the carboxylateÀmetal complex changes from unidentate to bridging bidentate when the average size of the QDs increases from 8 to 20 nm. 8 However, the average particle sizes of our TGA and MPA-capped QDs calculated are very similar (i.e., 3.20 nm for TGA-capped QDs and 3.07 nm for MPA-capped QDs using their first absorption maximum at 546 and 536 nm, respectively). 50 The small size difference between the two QD solutions is unlikely to cause a difference in the carboxylateÀ metal complex.…”

Section: Resultsmentioning

confidence: 57%

“…Several other studies have also proposed the same interaction between the thiol group and the core of the QDs. 8,38,39 Since no visible CdS LO mode at ∼300 cm À1 is observed, a CdS shell has not formed around the CdTe cores in the three solutions. Instead, a CdS x Te 1Àx ternary structure might have formed around the CdTe core, which is commonly formed upon heating processes.…”

Section: Resultsmentioning

confidence: 96%

“…Notably, the peaks between 1330 and 1500 cm À1 and between 1570 and 1580 cm À1 are attributed to the symmetric and asymmetric stretching modes of the carboxylates, respectively. 8,39,46 These modes are only observed in TGA, and MPA-capped QDs, in which one end of the thiol chain is terminated with a carboxylic acid group. These modes indicate that the carboxylic acid groups are absorbed onto the QD surfaces as carboxylates, most likely by forming bonds with the Cd ions on the CdTe core.…”

Section: Resultsmentioning

confidence: 99%

“…Colloidal quantum dots (QDs) are suspensions of semiconductor nanoparticles that offer both the intriguing optical properties of quantum-confined particles, and the practical advantages of solution-based processing. − In the past two decades, aqueous synthesis of colloidal QDs has gained much popularity and evolved tremedously. − This simple and cost-effective technique allows very small (2–6 nm), monodisperse, and highly water-soluble QDs to be synthesized in gram quantities. QD capping plays a pivotal role in the properties and utility of the material; the use of short-chain thiols, such as thioglycolic acid (TGA), as capping agents has been shown to greatly improve the photoluminescent (PL) quantum efficiency of as-synthesized QDs to values of 40–60% .…”

mentioning

confidence: 99%

See 3 more Smart Citations

Photonic Crystal Fiber for Efficient Raman Scattering of CdTe Quantum Dots in Aqueous Solution

et al. 2011

View full text Add to dashboard Cite

A novel hollow-core photonic crystal fiber platform was used for the first time to observe clear vibrational modes of the CdTe core, CdS(0.7)Te(0.3) interface, and carboxylate-metal complexes in dilute aqueous CdTe quantum dot (QD) solutions. These modes demonstrate the presence of crystalline cores, defects, and surface passivation responsible for photoluminescent efficiency and stability. In addition, 3-mercaptopropionic acid (MPA)-capped QDs show higher crystallinity and stability than those capped with thioglycolic acid (TGA) and 1-thioglycerol (TG). This detailed, nondestructive characterization was carried out using Raman spectroscopy for solutions with QD concentration of 2 mg/mL, which is similar to their concentration during synthesis process. This platform can be extended to the in situ studies of any colloidal nanoparticles and aqueous solutions of relevant biological samples using Raman spectroscopy.

show abstract

Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Photonic Crystal Fiber for Efficient Raman Scattering of CdTe Quantum Dots in Aqueous Solution

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The presence of these bands in the FTIR spectra confirms the existence of carboxylate moieties on the QD surface as found in other studies from the absorption of carboxylic acids on metal surfaces. [31][32][33] This is an expected result because of the use of basic pH that resulted in deprotonation of the acid to form carboxylate groups while ensuring complete dispersion of the QDs in water through the electrostatic repulsions. Another band located at $667 cm À1 is attributed to the C-S vibration, which clearly demonstrates the presence of ligand (cap) on the surface of the purified PbSe QDs.…”

Section: Characterization Of Pbse Qdsmentioning

confidence: 99%

Room temperature synthesis of PbSe quantum dots in aqueous solution: stabilization by interactions with ligands

et al. 2012

View full text Add to dashboard Cite

An aqueous route of synthesis is described for rapid synthesis of lead selenide quantum dots (PbSe QDs) at room temperature in an attempt to produce water-soluble and stable nanocrystals. Several thiol-ligands, including thioglycolic acid (TGA), thioglycerol (TGC), 3-mercaptopropionic acid (MPA), 2-mercaptoethyleamine hydrochloride (MEA), 6-mercaptohexanoic acid (MHA), and L-cysteine (L-cys), were used for capping/stabilization of PbSe QDs. The effects of the ligands on the stability of PbSe QDs were evaluated for a period of two months at room temperature under normal light conditions and at 4 °C in dark. The TGA- and MEA-capped QDs exhibited the highest stability prior to purification, almost two months when kept in dark at 4 °C. However, the stability of TGA-capped QDs was reduced substantially after purification to about 5 days under same conditions, while MEA-capped QDs did not show any significant instability. The stabilization energies of Pb-thiolate complexes determined by theoretical DFT simulations supported the experimental results. The PbSe QDs capped with TGA, MPA and MEA were successfully purified and re-dispersed in water, while those stabilized with TGC, MHA and L-cys aggregated during purification attempts. The purified PbSe QDs possess very susceptible surface resulting in poor stability for about 30 – 45 min after re-dispersion in water. In the presence of an excess of free ligand, the stability increased up to 5 days for TGA-capped QDs at pH 7.19, 9 –12 days for MPA-capped QDs at pH 7.3–7.5 and 45–47 days for MEA-capped QDs at pH 7.35. X-Ray Diffraction (XRD) results showed that the QDs possess a cubic rock salt structure with the most intense peaks located at 2θ = 25.3° (200) and 2θ = 29.2° (100). TEM images showed that the size of the QDs ranges between 5 and 10 nm. ICP-MS results revealed that Pb:Se ratio was 1.26, 1.28, 3.85, 1.18, and 1.31 for the QDs capped with TGA, MPA, MEA, L-Cys, and TGC, respectively. The proposed method is inexpensive, simple and utilizes environmentally friendly chemicals and solvents.

show abstract

Capping Ligand Influence on the Structural, Optical and Luminescence Properties of CdTe Nanoparticles Prepared by a Simple Wet Chemical Process

2019

View full text Add to dashboard Cite

The nature of the capping ligands used and the strength of their interactions with the surface atoms of the nanoparticles (NPs) impact greatly on the material properties and the stability of the resulting NPs. The structural analysis revealed that all the as-prepared CdTe NPs samples had a zinc blende crystal structure of different phases. The glutathione and L-cysteine capped CdTe NPs had the same zinc blende phase (JCPDS no. 75-2086) while thioglycolic acid capped and co-capped CdTe NPs possessed another zinc blende phase (JCPDS no. 75-2083). The calculated crystallite sizes were in the range 2-26 nm for all the samples. The optical spectroscopy studies showed various properties when different capping ligands were used. The band gap energies for all the as-prepared CdTe NPs confirmed the results obtained from the X-ray diffraction. The band gap energies were in the range of 2.39-3.34 eV for all the as-prepared CdTe NPs.[a] Dr.

show abstract

The role of potassium tellurite as tellurium source in mercaptoacetic acid-capped CdTe nanoparticles

Cited by 29 publications

References 33 publications

Photonic Crystal Fiber for Efficient Raman Scattering of CdTe Quantum Dots in Aqueous Solution

Photonic Crystal Fiber for Efficient Raman Scattering of CdTe Quantum Dots in Aqueous Solution

Room temperature synthesis of PbSe quantum dots in aqueous solution: stabilization by interactions with ligands

Capping Ligand Influence on the Structural, Optical and Luminescence Properties of CdTe Nanoparticles Prepared by a Simple Wet Chemical Process

Contact Info

Product

Resources

About