Papers by Keyword: Capping Agent

Abstract: The synthesis of Cd_0.5Zn_0.5S/PVP and Cr_x: Cd_0.5-xZn_0.5S/PVP(x = 0.02, 0.04, 0.06, 0.08) nanoparticles were carried out using a chemical co-precipitation reaction using homogeneous solutions of cadmium, zinc and chromium salts. The impact of Cr doping on the morphological, structural, and optical characteristics of nanoparticles was investigated in this study. Energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Diffuse Reflectance spectroscopy (DRS) have been utilized to examine the structural, optical, and morphological properties of elements. EDAX analysis verified the existence of chromium (Cr) within the cadmium zinc sulphide (CdZnS) crystal structure. The XRD analysis revealed that the Cr doped CdZnS nanoparticles exhibited crystallization in the zincblende structure, with a predominant orientation along the (1 1 1) plane. The nanoparticles have an average size ranging from 3 to 6 nm. The particle size determined from the SEM images corresponded with the findings from the XRD analysis. The DRS revealed that the increase in Cr concentration caused a shift of the absorption edge towards lower wavelengths. The bandgap energy estimates ranged from 3.85 to 4.05 eV. The blueshift is caused by the quantum confinement phenomenon.

Abstract: In this work, PtPd nanostructures have been synthesized via the chemical reduction method with different capping agents (i.e., PVA, PVP, and PEG), whilst the strong reducing agent, NaBH₄, was used in this study to reduce the metal salt to zero-valent PtPd nanostructures. Both PtPd synthesized with PVP and PEG exhibit nanoparticle structures, whereas PtPd synthesized in PVA demonstrates large, interconnected network structures. Pt-Pd synthesized with PVP exhibits a high ECSA value of 692.68 m²/g compared to without capping agent (287.80 m²/g) indicating large active sites, which increases its catalytic function. This study concludes that the presence of a capping agent influences the morphological structure and the catalyst's efficiency in performing a redox reaction at the surface.

Abstract: II–VI nanocrystalline semiconductor materails provide a wide range of applications in electronics, optoelectronics and photonics. The present paper reports the preparation of colloidal Cadmium selenide (CdSe) nanoparticles and study their optical properties. (CdSe) was produced by a chemical route procedure, with the ligand tri sodium citrate (TSC) serving as a complexing agent. Cadmium acetate is used as a Cd source, and sodium selenide is used as a Se precursor. The morphological and optical properties of the produced nanoparticles were determined using a Transmission electron microscopy (TEM) and Ultraviolet – Visible spectroscopy (UV-VIS).Thin films of CdSe capped with are deposited on the glass and aluminum substrates . AL/ CdSe/Ag MSM photodetectors have been fabricated and the electrical properties were measured in dark and light. The output data display that the photo currents of all diodes are increased with light. The fact that the films had dark electrical conductivity and photoconductivity indicates that they were semiconducting materials.

Abstract: Work represents the silver nanoparticles synthesis using green method by adding soluble starch in DMSO solution. The resulting AgNPs-based starch was noted via changing the color from yellow to brownish in aqueous DMSO solution in dark place due to the role of starch in the Ag ions reduction to AgNPs as capping agent in DMSO solvent at temperature 60^°C. Then, the AgNPs development was characterized via the (UV-Vis) spectrophotometer. The morphology, structure and polydispersion of AgNPs were determined by using FESEM, XRD and Zeta analyzer, respectively which improved the role of starch in the formation of spherical and flower shapes of AgNPs. Moreover, the antibacterial activity of AgNPs-based starch revealed a strong effect against the positive bacteria than the negative bacteria as compared with the other antibiotic. Besides, these results suggest that the AgNPs prepared by green method can be utilized as efficient antimicrobial agent in the fields of medicine and represented the opportunities for the formation of safe and friendly AgNPs.

Abstract: The synthesis of gold nanoparticles (AuNPs) was carried out by reacting chloroauric acid [AuCl₄]^‒ and glutamic acid solution in a water bath at 80 °C. The reaction was confirmed by the color change from colorless solution into pink. Various concentrations of the glutamic acid solution, reaction times and pH were examined to determine the optimum condition of AuNPs synthesis. The AuNPs colloid was characterized by UV-Visible spectrophotometer at wavelength 350-800 nm, particle size analyzer (PSA) and transmission electron microscope (TEM). The optimum synthesis condition for obtained [AuCl₄]^‒ was 4 mM glutamic acid solution at pH 11 and 60 min reaction. TEM results showed that the particles were round in shape with the article size indicated by PSA was 40 nm.

Abstract: Synthesis and stability of silver nanoparticles (AgNPs) using tyrosine as a reducing and capping agent have been done. Synthesis of AgNPs was performed by mixing silver nitrate (AgNO₃) solution as a precursor with tyrosine amino acid and heating it in a boiling water bath until characterized by the appearance of color change from colorless to yellow. Variations in pH, concentration, and reaction time affecting the formation of AgNPs were studied using UV-Vis spectrophotometry in the wavelength range of 300-700 nm as the main device. The synthesis was successfully conducted at pH 11 for 45 min with the optimum tyrosine concentration was 3 mM for 0.5 mM AgNO₃. The optimum mole ratio AgNO₃ 0.5 mM to tyrosine 3 mM was 1:6. TEM and PSA characterizations showed that the particle was a round shape and 29.5 nm is average size, respectively.

Abstract: We report our investigation of roles of polyvinyl alcohol (PVA) as a high-performance capping agent in synthesizing silver nanowires (AgNWs) using polyol method. For this purpose, we varied the concentration of silver nitrate (AgNO3), from 0.3 M to 1.0 M, and molar ratios of [PVA:AgNO3] from 2 to 6. The UV-vis spectra show the AgNWs growth optimally at a molar ratio of 4.5 with the absorbance peaks of 378 nm and 380 nm. Meanwhile, from XRD patterns, it was found that the crystal structure of the AgNWs can be identified as a face-centered cubic (fcc) with a lattice constant according to the spacing distance between the {111} planes of 4.087 Å. Finally, scanning electron microscopy (SEM) and transmission electron microscopy TEM images show the diameter and length of the AgNRs are 150 to 230 nm and 50 to 120 µm, respectively. These results show that the AgNWs synthesized using PVA having a long size.

Abstract: Effect of temperature on the formation of silver nanorods (AgNRs) synthesized using polyol method has been investigated. In this experiment, materials were used silver nitrate (AgNO₃) as main raw material, ethylene glycol (EG) as a solvent, small amount of sodium chloride (NaCl) as a mediated agent, while polyvinyl alcohol (PVA) as a capping agent to assist the growth of AgNRs. To apply a constant temperature at each synthesis process, an Erlenmeyer flask containing the sample was immersed in a controllable magnetic stirrer oil bath. It is found that the presence of heat as represented by the temperature of oil bath has been shown to have a strong impact on the AgNRs formation. The scanning electron microscope (SEM) confirmed uniform and high density of AgNRs when the oil bath temperature during polyol process was 140 °C. In the same condition, the UV-vis spectra also confirmed formation process of AgNRs with appearance of the transverse plasmon peak about 350 nm. Finally, the X-ray diffraction (XRD) pattern represented that the final product of AgNRs was highly crystallized.

Abstract: The biosynthesis of nanostructures using plant extract (green chemistry) has emerged as an ecofriendly and evergreen branch of nanoscience and nanotechnology for the development of biomedical applications. In this study we report the use of aqueous extract of the latex of Thevetia peruviana (TP) for the synthesis of gold nanoparticles (AuNPs). The reaction time was optimized for maximum yield of AuNPs. The AuNPs formed were characterized using FTIR, EDS, TEM and XRD. The formation of AuNPs was confirmed using SPR spectra observed at around 589 nm. XRD pattern shows the FCC crystal structure of the nanoparticles, orresponding to (111), (200), (220) and (311) faces of gold. TEM analysis revealed that the particles are spherical with size distributions ranging from 41-50 nm. HRTEM image showed 2.35Å interplaner spacing. FTIR analysis confirmed that the flavonoid and reducing sugar found in the extract were the main reductive and the protein was capping components in the biosynthesis of AuNPs.

Abstract: RETRACTED PAPER: The fabrication of nanospinel zinc chromite (ZnCr₂O₄) crystals by the means of thermal treatment method from an aqueous solution containing metal nitrates, polyvinyl pyrrolidone (PVP), and deionized water was described in this study. The samples were calcined at various temperatures ranging from 773 to 973 K for the decomposition of the organic compounds and crystallization of the nanocrystals. PVP was used as capping agent to control the agglomeration of the particles. The characterization studies of the fabricated samples were carried out by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), energy dispersed X-ray spectroscopy (EDX) and electron spin resonance spectroscopy (ESR). The corresponding peaks of Zn, Cr and O were observed in the EDX spectrum of the sample which confirms the formation of ZnCr₂O₄. The XRD patterns also confirmed the formation of the single faced nanocrystallines of spinel ZnCr₂O₄ with a face-centered cubic structure. The average particle size of the synthesized crystals was also determined from the XRD patterns using the Scherers formula which shows that the crystallite sizes increases with increase in calcination temperature and was in good agreement with the TEM images which shows cubical ZnCr₂O₄ nanocrystals with uniform morphology and particle size distributions. The ESR spectra confirmed the existence of unpaired electron in the fabricated samples and the increase in g-factor and decreases in resonant magnetic field (H_r) were observed as the calcination temperature increases.