Presence Of Oleylamine Research Articles

Study on synthesis and photocatalytic activity of novel visible light sensitive photocatalyst Ag<SUB align="right">3PO<SUB align="right">4

Silver orthophosphate nanoparticles have been synthesised by precipitation of AgNO3 and H3PO4 in presence of oleylamine and other solvents like toluene, and ethanol at room temperature. Particle sizes of silver orthophosphate nanocrystals can be controlled by adjusting the amount of water. The products were characterised by XRD, UV–Vis, FESEM and EDX. The characterisation results showed that the crystal sizes of products were 5–20 nm depending on the content of water. UV–Vis result revealed a strong light absorbance in the visible light region at 465–470 nm. Photocatalytic activities of titania and silver orthophosphate nanocrystals were tested in photocatalytic degradation of Methylene Blue (MB) in liquid phase under visible light irradiation. Samples showed very high photocatalytic activity in the degradation of Methylene Blue. After 2h of reaction, the conversion reached the value of 97%.

Preparation and Characterization of NiO Nanoparticles through Thermal Decomposition of Bis(glycinato)Nickel(II)dihydrate

NiO nanoparticles were successfully prepared by decomposing the predecessor bis(glycinato)nickel(II)dihydrate in the presence of oleylamine and triphenylphosphine (TPP), and different approaches including Fourier transforms infrared spectrometry(FT-IR), X-ray diffraction(XRD) and transmission electron microscopy (TEM) were used to characterize the NiO nanoparticles. Meanwhile, the effects of TPP concentration and reaction time on the size and yield of NiO nanoparticles derived from precursors were thoroughly investigated in this paper. The analysis results indicated that the prepared NiO nanoparticles were found spherical in shape and demonstrated weak agglomeration. They had generally high purity and a fine crystal phase of cubic syngony. Furthermore, the effects of the TPP concentration and reaction time on the size and yield of NiO nanoparticles are very crucial, higher concentration of TPP would results in reduction of both the mean size and yield of NiO particles. However both yields and particles size of NiO nanoparticles continuously increased as increasing reaction time, after more than 60 minutes, the size and yield of NiO nanoparticles kept hardly change.

Chemically Designed Growth of Monodisperse Iron Oxide Nanocrystals

We describe here a chemically controlled pathway for the designed synthesis of iron oxide nanoparticles by thermal decomposition of iron(II) and iron(III) oxalates in high-boiling solvents in the presence of oleylamine and oleic acid acting as capping ligands. The phase composition of the nanocrystals (Fe, FeO, Fe3O4, or α-Fe2O3) could be precisely controlled by adjusting the synthesis conditions or by addition of appropriate oxidants, such as trimethylamine-N-oxide (TMAO), which produced highly monodisperse iron(III) oxide particles in the range of 6–25 nm in good yields. The decomposition behavior of different precursor/TMAO mixtures was elucidated by differential scanning calorimetry and thermogravimetry, and resulting particles were characterized by comprehensive HR-TEM and XRD analyses.

Simple solvothermal synthesis of hydrophobic magnetic monodispersed Fe3O4 nanoparticles

A new solvothermal method is proposed for the preparation of Fe3O4 nanoparticles (NPs) from iron acetylacetonate in the presence of oleylamine and n-hexane. The products are characterized by X-ray powder diffraction, infrared (IR) spectroscopy, transmission electron microscopy, thermogravimetry/differential thermogravimetry (TG/DTG) analysis, and vibrating sample magnetometery. The new procedure yields superparamagnetic monodispersed Fe3O4 particles with sizes ranging from 7nm to 12nm. The nanocrystal sizes are controlled by adjusting the volume ratio of oleylamine to n-hexane. IR and TG/DTG analyses indicate that the oleylamine molecules, as stabilizers, are adsorbed on the surface of Fe3O4 NPs as bilayer adsorption models. The surface adsorption quantities of oleylamine on 7.5 and 10.4 nm-diameter Fe3O4 NPs are 18% and 11%, respectively. The hydrophobic surface of the obtained nanocrystals is passivated by adsorbed organic solvent molecules. These molecules provide stability against agglomeration, enable solubility in nonpolar solvents, and allow the formation of magnetic polymer micelles.

Highly photocatalytic activity of novel nano-sized Ag3PO4 for Rhodamine B degradation under visible light irradiation

Ag3PO4 nanoparticles have been successfully synthesized by precipitation of AgNO3 and H3PO4 in the presence of oleylamine. The products were characterized by XRD, UV–vis and FE-SEM. It showed that the particle sizes of products ranged from 5 to 10nm depending on the synthesis conditions. UV–vis result revealed a strong light absorbance in the visible light region at 470–475nm. Photocatalytic activities of TiO2 and Ag3PO4 nanoparticles were tested in photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. In comparison to nano-TiO2, nano-sized Ag3PO4 samples exhibited much higher photocatalytic activity in the RhB degradation. After 3h of reaction, the conversion reached the value of 96%.

Size-dependent transformation from Ag templates to Au–Ag nanoshells via galvanic replacement reaction in organic medium

The transformation from Ag templates to Au–Ag nanoshells via galvanic replacement reaction with HAuCl4 was systematically studied in an organic medium in the presence of oleylamine. Decahedral (~43 nm in size) and triangular prism (~53 nm in edge length) Ag templates transformed into equiaxed and triangular prismatic Au–Ag nanoshells, respectively. The first step involved structural and morphological changes from Ag templates to Au–Ag nanoshells with an interior cavity. In the second step, the growth of the shells continued through the deposition of Au. The shell thickness increased from ~5 to ~10 nm for the equiaxed Au–Ag nanoshells (~39-nm interior cavity) and ~5 to ~8 nm for the triangular prismatic Au–Ag nanoshells (~52-nm interior edge length). Oleylamine not only served as a surfactant but also removed AgCl precipitates and reduced HAuCl4. For the nanoshells derived from the ~20-nm Ag decahedrons, further reaction in excess HAuCl4 collapsed the nanoshells into Au-rich solid fragments. However, the nanoshells derived from the ~43-nm Ag decahedrons, the nanoshell structure not only persisted in excess HAuCl4, but its shell thickness also increased. The size-dependent transformation of these nanoshells is discussed.

One-pot solvothermal synthesis of mixed Cu-Ce-Ox nanocatalysts and their catalytic activity for low temperature CO oxidation

One-pot solvothermal method has been developed for the synthesis of high-surface area Cu-Ce-Ox binary nanocatalysts with various Cu contents in the presence of oleylamine as capping agent. The obtained binary nanocatalysts were characterized by different techniques including XRD, H2-TPR, TEM, BET and XPS. The influence of Cu contents on their catalytic performance for the CO oxidation was also studied. Our results revealed that the Cu-Ce-Ox binary nanocatalysts show the better catalytic activity compared to those of the conventional Cu-Ce-Ox, bare nano-CeO2 and nano-CuO catalysts. This is ascribed to mutual interaction and synergistic effect between copper oxide species and cerium oxide. Among the obtained nanocatalysts, the Cu-Ce-Ox nanocatalyst with 5.6wt% Cu (noted as 5.6-Cu-Ce-Ox) exhibits the best catalytic activity; the 50% CO conversion can be reached at 55°C. H2-TPR profiles show two reduction peaks at low and high temperatures for these catalysts, which could be attributed to the reduction of highly dispersed CuO on the CeO2 surface and the bulk-like CuO species, respectively. Using the one-pot solvothermal synthesis developed in this study, 6–8wt% Cu content is needed for the high catalytic activity for the CO oxidation at low temperature.

One-Pot Low Temperature Synthesis of Monodisperse Silver Nanoparticles

A facile one-pot route for the synthesis of monodisperse Ag nanocrystals with a narrow size distribution is described. Uniform Ag nanoparticles with the size of around 12 nm were obtained by reduction of AgNO3 in the presence of oleylamine and polymer polyvinylpyrrolidone (PVP) at low temperature. It is found that temperature has a significant effect on the sizes and the size distributions of the nanoparticles. Because irregular Ag nanoparticles are produced easily due to Ostwald ripening or kinetic control at both high temperature and low temperature, respectively, uniform nanocrystals can be obtained at an appropriate temperature (70 degrees C).

CoO nanocrystals as a highly active catalyst for the generation of hydrogen from hydrolysis of sodium borohydride

We report the excellent catalytic performance of CoO nanocrystals on the catalytic hydrolysis of alkaline NaBH4 solutions. CoO nanocrystals with octahedral and near-spherical shapes are synthesized using a facile chemical solution method that employed cobalt acetate tetrahydrate as metal precursor in the presence of oleylamine. The octahedral CoO nanocrystals typically have a size of 40–50 nm, while the near-spherical nanocrystals have a size varying from 8 to 13 nm. Both of them have a face centered cubic (fcc) crystalline phase. Catalytic tests show that the as-synthesized CoO nanocrystals exhibit very high activities for the H2 generation from the hydrolysis of alkaline NaBH4 solutions. The maximum hydrogen generation rate of the as-synthesized CoO nanocrystals exceeds most reported values of transition metal or noble metal contained catalysts performed in alkaline NaBH4 solutions. The influences of shape on the catalytic behaviors of as-synthesized CoO nanocrystals are also compared and analyzed. The results presented in this study indicate that CoO nanocrystals are a promising candidate to replace noble metal catalysts in the H2 generation from the hydrolysis of borohydrides.

Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine (OAm) and oleic acid (OA). The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum (SERS) property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.

Functionalized Fe3O4@Au superparamagnetic nanoparticles: in vitro bioactivity

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe3O4@Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10–15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe3O4@Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cells for glucose conjugated nanoparticles.

A facile synthesis of nearly monodisperse ruthenium nanoparticles and their catalysis in the hydrolytic dehydrogenation of ammonia borane for chemical hydrogen storage

A facile method for the preparation of nearly monodisperse Ru nanoparticles (NPs) and their record catalytic activity in the hydrolytic dehydrogenation of ammonia borane (AB) for chemical hydrogen storage are reported herein. Ru NPs were prepared by a novel protocol comprising the thermal decomposition and concomitant reduction of ruthenium(III) acetylacetonate (Ru(acac)3) in the presence of oleylamine (OAm) and benzylether (BE). In the protocol, OAm served as both a stabilizer and reducing agent and BE used as a solvent. Ru NPs were supported on aluminum oxide nanopowder (Ru@Al2O3) via a simple liquid impregnation method before their use as catalyst for the dehydrogenation of AB in water. Without any special treatment to remove the surfactants, Ru@Al2O3 showed high catalytic activity in the hydrolytic dehydrogenation of AB providing an initial turnover frequency (TOF) of 39.6molH2(molRumin)−1. Their catalytic performance was further enhanced dramatically by the acetic acid treatment and the initial TOF value is increased to 83.3molH2(molRumin)−1 that is the highest among the reusable Ru catalysts and even higher than Pt-based catalysts tested in the hydrolysis of AB. Additionally, the work reported here includes a wealth of kinetic data to determine the rate law and apparent activation parameters for the catalytic dehydrogenation of AB in water.

Methanolysis of Ammonia Borane by CoPd Nanoparticles

Monodisperse 7 nm CoPd nanoparticles (NPs) with controlled compositions were synthesized and studied for their catalyzing methanolysis of ammonia borane (AB). The NPs were prepared by the reduction of cobalt(II) acetylacetonate and palladium(II) bromide in the presence of oleylamine and trioctylphosphine. Deposited on a carbon support without any specific surface treatment, these NPs were active catalysts for methanolysis of AB, and their activities were composition-dependent. Among all CoPd catalysts tested, Co48Pd52 NPs exhibited the highest catalytic activity and stability. Kinetic study showed that the catalytic methanolysis of AB was first-order with respect to catalyst concentration and zero-order with respect to AB concentration. The activation energy for the methanolysis was calculated to be 25.5 kJ mol–1. These CoPd NPs are a promising catalyst for AB methanolysis and for developing a highly efficient hydrogen generation system for power applications.

Hydrolytic dehydrogenation of ammonia borane catalyzed by reduced graphene oxide supported monodisperse palladium nanoparticles: High activity and detailed reaction kinetics

A highly active and stable catalyst for the hydrolytic dehydrogenation of ammonia borane (AB) was prepared by supporting monodisperse palladium nanoparticles (Pd NPs) on reduced graphene oxide (RGO) via a facile method. RGO was prepared via modified chemical route and used as support matrices for monodisperse Pd NPs that were formed by the reduction of palladium(II) acetylacetonate by borane tert-butylamine complex in the presence of oleylamine. RGO supported Pd NPs (RGO@Pd) show high activity and stability in the hydrolytic dehydrogenation of AB. The RGO@Pd catalysts provide the turnover frequency of 26.3min−1—the best among the all Pd-based catalysts and even comparable to Pt-based catalysts tested in the hydrolysis of AB. They are also very stable catalysts providing 11,600 total turnovers in 46h. The detailed reaction kinetics of catalytic hydrogen generation from the hydrolysis of AB revealed that the reaction proceeds first order with respect to the Pd concentration and zeroth order with respect to the AB concentration. The apparent activation parameters of the catalytic hydrolysis reaction were also calculated; apparent activation energy (Eaapp)=40±2 kJ mol−1, activation enthalpy (ΔH#,app)=38±1kJmol−1 and activation entropy (ΔS#,app)=−134±1JK−1mol−1.

Synthesis of Nickel Oxide Nanoparticles from Thermal Decomposition of a New Precursor

Nickel oxide nanoparticles (25 nm) have been synthesized via decomposition of a new precursor nickel octanoate Ni(octa)2 in the presence of oleylamine (C18H37N) and triphenylphosphine (C18H15P), in mild conditions. To control the particle size and morphology, combination of C18H15P and C18H37N were applied as surfactants. In this process, oleylamine was used as both the medium and the stabilizing reagent. C18H37N and C18H15P play an important role in preventing aggregation of NiO nanoparticles. The products were characterized by XRD, SEM, TEM, FT–IR, and TGA.

Novel NiO nanodisks and hollow nanodisks derived from Ni(OH)2 nanostructures and their catalytic performance in epoxidation of styrene

A microwave-solvothermal (MS) method combining a calcination process was conducted to synthesize nickel oxide (NiO) nanodisks and hollow nanodisks. First, Nickel hydroxide (Ni(OH)2) nanodisks and hollow nanodisks had been synthesized through the MS method in the presence of oleylamine or sodium oleate. The X-ray powder diffraction (XRD) results of the products illustrate that the as-prepared nanostructures have a Ni(OH)2 and NiO phase. The transmission electron microscopy (TEM) images of the products illustrate that Ni(OH)2 nanodisks prepared in the presence of oleylamine have a thickness of ~10nm and diameter of ~100nm, while Ni(OH)2 hollow nanodisks synthesized in the presence of sodium oleate have a hole in the middle with a thickness of ~10nm and diameter of ~250nm. Second, the NiO nanodisks and hollow nanodisks could be obtained from the precursor without changing their morphologies by a simple calcination procedure. The as-synthesized NiO nanostructures displayed efficient catalytic epoxidation of styrene with conversion (60%) and selectivity (60–80%).

Palladium nanoparticles supported on chemically derived graphene: An efficient and reusable catalyst for the dehydrogenation of ammonia borane

Chemically derived graphene (CDG) was prepared by hydrazine hydrate reduction of graphene oxide and used as support for palladium nanoparticles (Pd NPs) generated ex situ with controllable particle size and dispersion. The Pd NPs supported on CDG were well characterized by using a combination of advance analytical techniques and employed as catalyst in the dehydrogenation and hydrolysis of ammonia borane (AB) in organic solvents and aqueous solutions, respectively. Monodisperse Pd NPs of 4.5 nm were prepared from the reduction of palladium(II) acetylacetonate by tert-butylamine borane in the presence of oleylamine. They were readily impregnated on CDG which has BET surface area of 500 m2 g−1. Pd NPs retain their particle size dispersion and stability when supported on chemically derived graphene. The resulting materials are highly active and stable catalyst for the dehydrogenation and hydrolysis of AB. In addition to their high activity and stability, these Pd NPs are also reusable catalyst in both dehydrogenation and hydrolysis of AB preserving 85% and 95% of initial activity after 5th and 10th runs, respectively.

Size and Composition Control of Pt–In Nanoparticles Prepared by Seed-Mediated Growth Using Bimetallic Seeds

A two-step method has been developed for precise size and composition control of bimetallic Pt-In nanoparticles. Very small (1.62 nm) PtIn seed nanoparticles with 1:1 metal ratio were prepared in the absence of capping agents followed by growth of Pt on their surface in the presence of oleyl amine as reducing and stabilizing agent. Nanoparticles with bulk compositions of Pt(4)In, Pt(3)In, and Pt(2)In could be synthesized with average diameter smaller than 3 nm. TEM, EDX, and XPS provided evidence for homogeneous growth without separate nucleation of pure platinum nanoparticles in the reaction solution. Pt(3)In nanoparticles were deposited onto SiO(2) surface by incipient wetness impregnation. Temperature-induced changes in the particle surface were monitored by in situ IR spectroscopy and CO adsorption. It was found that surface alloy composition of the particles could be tuned by using oxidizing or reducing atmospheres.

Synthesis and characterization of FePt nanoparticles by high energy ball milling with and without surfactant

FePt nanoparticles were prepared by high energy ball milling (HEBM) in two different ways. In the first one, elemental powders were mixed and milled whereas in the second one the milling was performed in the presence of oleyl amine and oleic acid as surfactants and hexane as a solvent. X-ray diffraction shows that when the milling is performed in dry conditions, Fe and Pt are alloyed after 5h, whereas in the wet milling procedure alloying does not take place. In the first case, the diffraction pattern corresponds to the disordered FCC phase. This behavior is also corroborated by the evolution of the magnetic characteristics. In the case of the alloy obtained in dry conditions, the powder was heat treated in order to induce the transformation to the ordered phase. Coercivities of 2.5kOe are obtained after 650°C for 2h.

Synthesis and morphology control of surface functionalized nanoscale yttrium aluminum garnet particles via supercritical hydrothermal method

Organic-functionalized nanoscale yttrium aluminum garnet (YAG) particles were synthesized via a simple rapid supercritical hydrothermal method in the presence of oleylamine and oleic acid as organic surface modifiers. The presence of the organic molecules resulted in the various morphologies of the produced YAG particles, including cubic, spherical and chainlike structures. Because of their hydrophobic surface character, as-synthesized particles were dispersible in organic solvents.