Tri-n-octylphosphine Research Articles

An insight into the mechanism of charge-transfer of hybrid polymer:ternary/quaternary chalcopyrite colloidal nanocrystals.

In this work, we have demonstrated the structural and optoelectronic properties of the surface of ternary/quaternary (CISe/CIGSe/CZTSe) chalcopyrite nanocrystallites passivated by tri-n-octylphosphine-oxide (TOPO) and tri-n-octylphosphine (TOP) and compared their charge transfer characteristics in the respective polymer: chalcopyrite nanocomposites by dispersing them in poly(3-hexylthiophene) polymer. It has been found that CZTSe nanocrystallites due to their high crystallinity and well-ordered 3-dimensional network in its pristine form exhibit a higher steric- and photo-stability, resistance against coagulation and homogeneity compared to the CISe and CIGSe counterparts. Moreover, CZTSe nanocrystallites display efficient photoluminescence quenching as evident from the high value of the Stern–Volmer quenching constant (KSV) and eventually higher charge transfer efficiency in their respective polymer P3HT:CZTSe composites. We modelled the dependency of the charge transfer from the donor and the charge separation mechanism across the donor–acceptor interface from the extent of crystallinity of the chalcopyrite semiconductors (CISe/CIGSe/CZTSe). Quaternary CZTSe chalcopyrites with their high crystallinity and controlled morphology in conjunction with regioregular P3HT polymer is an attractive candidate for hybrid solar cells applications.

Liquid–liquid extraction of Li+ using mixed ion carrier system at room temperature ionic liquid

An environmentally benign technique for the separation and recovery of lithium (Li+) from aqueous streams, containing mixed metal ions was developed via liquid–liquid extraction (LLE). Hydrophobic room temperature ionic liquids (RTIL) were tested as the main extracting solvents. To increase the metal extraction, a proton-ionizable agent bis(2-ethylhexyl) phosphoric acid (DEHPA) was added into the RTIL. To enhance the metal uptake selectivity, three Li+-selective neutral ion carriers such as 6-hydroxy-dibenzo-14-crown-4, dibenzo-14-crown-4, and tri-n-octyl-phosphine (TOPO) were also used and tested as extractant additives. Among the tested RTILs, phosphonium-based CYPHOS IL 109 was the most stable extractant as it exhibited the lowest loss when contacted with water. Addition of proton-ionizable agent DEHPA in CYPHOS IL 109 afforded a high extraction of multivalent cations with negligible recovery of monovalent metals. On the other hand, the addition of neutral ion carrier TOPO in DEHPA/CYPHOS IL 109 extractant resulted in a selective Li+ uptake which was maximized when the pH of the aqueous solution was maintained at 13, with TOPO/DEHPA molar ratio = 8. The overall process could be a two-stage LLE system wherein the unwanted multivalent cations are initially removed using DEHPA/CYPHOS IL 109 followed by the selective extraction of Li+, using TOPO/DEHPA/CYPHOS IL 109 system.

A Neutral 1D Coordination Polymer Constructed from the NiII Complex of the N‐Phosphorylated Thiourea PhNHC(S)NHP(O)(OPh)2 and Pyrazine: A Single‐Source Precursor for Nickel Nanoparticles

AbstractThe N‐phosphorylated thiourea PhNHC(S)NHP(O)(OPh)2 (HL) was synthesized by the reaction of PhNH2 and (PhO)2P(O)NCS. Reaction of the KL salt, generated in situ, with NiCl2 leads to pale violet [NiL2] with a 1,3‐N,S‐ coordination mode of the ligands. Interaction of [NiL2] with pyrazine (pz) yields the 1:1 coordination polymer [NiL2pz]n. An unexpected change in the coordination mode of the phosphorus‐containing ligands L from 1,3‐N,S‐ to 1,5‐O,S‐ was found in [NiL2pz]n upon coordination of additional donor ligands. [NiL2pz]n dissolved in tri‐n‐octylphosphine (TOP) was decomposed in hot hexadecylamine to give capped face‐centered cubic Ni nanoparticles with an average particle size of 17(2) nm.

Low temperature synthesis of anacardic-acid-capped cadmium chalcogenide nanoparticles

We report the low temperature synthesis of CdE (E = S, Se and Te) semiconductor nanoparticles capped by anacardic acid, an environmentally benign nat- urally occurring capping ligand. The cadmium chalcogen- ide nanoparticles were synthesized by reacting the reduced chalcogen powder with cadmium chloride to form the corresponding bulk material which was then dispersed in tri-n-octylphosphine (TOP) and thermolysed in anacardic acid. The low temperature of the reaction and the use of a naturally occurring oil solvent make this a relatively green synthetic route. The optical properties of the anacardic- acid-capped cadmium chalcogenide particles show evi- dence of quantum confinement. The particles were char- acterized by X-ray diffraction and electron microscopy techniques.

Green synthesis of gold nanoparticles using extracts of Artocarpus Lakoocha fruit and its leaves, and Eriobotrya Japonica leaves

Gold nanoparticles (AuNPs) synthesis is demonstrated successfully using fresh young leaves of Artocarpus Lakoocha (A. Lakoocha), fruit pulp of A. Lakoocha and loquat (Eriobotrya Japonica) leaves. We have also compared green synthesis with chemical assisted tri-n-octyl-phosphine (TOP) stabilized gold nanoparticles. Samples were characterized with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and UV-Visible spectroscopy. TEM images have shown that the average size of the particles is 15.06, 36.8 and 25.08 nm for A. Lakoocha fruits, A. Lakoocha leaves and loquat leaves assisted gold nanoparticles, respectively. Hydrogen tetrachloroaurate is reduced and AuNPs are stabilized by phenols, hydroxyls and carboxyls groups such as terpenoids, flavonoids, tannins etc, present in young leaves and fruit extracts. It was observed that green synthesis using botanical extracts is a cost effective and non- toxic way for nanoparticle preparation.

Phase-Pure Crystalline Zinc Phosphide Nanoparticles: Synthetic Approaches and Characterization

Zinc phosphide may have potential for photovoltaic applications due to its high absorptivity of visible light and the earth abundance of its constituent elements. Two different solution-phase synthetic strategies for phase-pure and crystalline Zn3P2 nanoparticles (∼3–15 nm) are described here using dimethylzinc and vary with phosphorus source. Use of tri-n-octylphosphine (TOP) with ZnMe2 takes place at high temperatures (∼350 °C) and appears to proceed via rapid in situ reduction to Zn(0), followed by subsequent reaction with TOP over a period of several hours to produce Zn3P2 nanoparticles. Some degree of control over size was obtained through variance of the TOP concentration in solution; the average size of the particles decreases with increasing TOP concentration. With the more reactive phosphine, P(SiMe3)3, lower temperatures, ∼150 °C, and shorter reaction times (1 h) are required. When P(SiMe3)3 is used, the reaction mechanism most likely proceeds via phosphido-bridged dimeric Zn(II) intermediates, ...

Microwave‐assisted synthesis of CuInSe2 nanoparticles in low‐absorbing solvents

Copper indium diselenide (CIS) nanoparticles were synthesized using a microwave‐assisted one‐pot solvothermal approach. For these studies high microwave‐absorbing precursors were used in combination with low microwave absorbing solvents tri‐n‐octylphosphine (TOP) and oleic acid (OA) to investigate the effect of selective heating of the precursors on nanoparticle synthesis. High‐resolution transmission electron microscopy (TEM) results indicated that the nanoparticles were spherical, crystalline and 4–5 nm in diameter. X‐ray diffraction (XRD) results indicated that the nanoparticles had a body‐centered tetragonal structure with planar defects that decreased in concentration with increasing reaction temperature and reaction time. The nanoparticle compositions varied depending on the reaction conditions and the compositions were found to approach stoichiometry for increased reaction times. Fourier transform infrared (FTIR) spectroscopy indicated both solvents adsorbed to the nanoparticle surface and energy dispersive spectroscopy indicated that these ligands became chlorinated during the reaction. The uniform temperature profile offered by the microwave heating allowed for highly reproducible batch‐to‐batch reactions, allowing for tight control over composition and defect concentration.

Defining Crystalline/Amorphous Phases of Nanoparticles through X-ray Absorption Spectroscopy and X-ray Diffraction: The Case of Nickel Phosphide

In this study we elucidate the structural distinctions between amorphous and crystalline Ni2P nanoparticles synthesized using tri-n-octylphosphine (TOP), through X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and inductively coupled plasma (ICP). We determine the differences in their chemical and atomic structure, which have not been previously reported, yet are essential for understanding their potential as nanocatalysts. These structural characteristics are related to the corresponding nanoparticle magnetic properties analyzed by performing magnetic measurements. XAS results reveal a significant P concentration in the amorphous nanoparticle sample – placing the stoichiometry close to Ni2P – despite XRD results that show only fcc Ni contributions. By comparing the long-range structural order from XRD to the short-range radial structure from EXAFS we conclude that both techniques are necessary to obtain a complete structural picture of amorphous and crystalline nanoparticle phases due to th...

Synthesis of non-spherical CdSe nanocrystals

Non-spherical CdSe quantum dots were synthesized through high temperature reduction of cadmium and selenium in the presence of TOP (tri-n-octylphosphine) and TOPO (tri-n-octylphosphine oxide). The high affinity of phosphine oxide to the surface of CdSe nanocrystals typically leads to the formation of spherical particles with diameters between 1.5 and 10 nm. However, with lower temperatures and longer reaction times relative to conventional synthesis techniques, the formation of non-spherical nanocrystals dominated. The three reaction temperatures that were studied were 230, 250, and 270 °C. Results verify the need to quench CdSe nanocrystals immediately following the injection of selenium dissolved in TOP (TOPSe) if spherical particles are the desired shape. Nanocrystal shape evolves from sphere to rectangle to hexagon or triangle as the reaction time is extended regardless of temperature. The highest yield of rectangular particles (~89 %) was achieved while maintaining a temperature of 250 °C for 20 min.

Unintended Phosphorus Doping of Nickel Nanoparticles during Synthesis with TOP: A Discovery through Structural Analysis

We report the discovery of unintentional phosphorus (P) doping when tri-n-octylphosphine (TOP) ligands are used in Ni nanoparticle synthesis, which is the most common method for monodisperse Ni nanoparticle synthesis. The nanoparticles appear pure face-centered cubic (fcc) Ni in X-ray diffraction despite the surprisingly high level (5 atomic %) of P. We find that the P doping follows a direct relationship with increased reaction time and temperature and that the P doping can be estimated with the degree of lattice expansion shown from a peak shift in the XRD spectrum. Through EXAFS modeling and density-functional (DFT) calculations of defect formation energies we find that the P atoms are preferentially located on the fcc lattice as substitutional dopants with oxidation state of zero. Magnetic and catalytic properties are shown to be greatly affected by this doping; DFT calculations show magnetization losses in the Ni system, as well as in Fe and Co systems. These findings are likely relevant for other metal syntheses that employ phosphine ligands.

Hollow-fiber liquid phase microextraction for lignin pyrolysis acids in aerosol samples and gas chromatography–mass spectrometry analysis

A method based on three-phase hollow fiber liquid phase microextraction was developed and successfully applied to aerosols for the analysis of lignin pyrolysis acids such as syringic acid, vanillic acid and p-salicylic acid. Important parameters related to extraction process like organic solvent for membrane phase, tri-n-octylphosphine (TOPO) oxide contents in organic solvent, stirring speed, extraction time etc. were optimized. 6-Undecanone with 15% TOPO contents (w/v) was found a suitable solvent for organic liquid membrane, 900 rpm was the optimum stirring speed and time of 4h was found optimum extraction time. Donor phase pH was 1.3 while acceptor phase pH was adjusted to 9.5. The optimized extraction method was used for the extraction of real aerosol samples. Analytes were derivatized using BSTFA containing 1% trimethylsilyl chloride and gas chromatography mass spectrometry was used for analysis. Very low limits of detection in the range 0.2-1.0 ng L(-1) were found, corresponding to 10-50 pg m(-3) of analytes in aerosols. Extraction efficiency obtained ranged 60.3-71.7% and enrichment factors ranged 3015-3585 times. The optimized method was successfully applied to aerosol samples and all of the selected analytes were detected in the analyzed samples.

Influence of the coordination mode in [Ni{RC(S)NP(S)(OiPr)2}2] for the formation of nickel-containing nanoparticles

The complex [Ni{2-PyNHC(S)NP(S)(OiPr)(2)-1,5,7-N,N',S}(2)] ([NiL(I)(2)]) dissolved in tri-n-octylphosphine (TOP) is decomposed in hot hexadecylamine (HDA) to give TOP-capped Ni nanoparticles. The same procedure using [Ni{2-MeC(6)H(4)NHC(S)NP(S)(OiPr)(2)}(2)-1,3-N,S] ([NiL(II)(2)]) and [Ni{PhC(S)NP(S)(OiPr)(2)-1,5-S,S'}(2)] ([NiL(III)(2)]) leads to the formation of NiS nanoparticles with the rhombohedral and hexagonal structures, respectively. NiH(x) nanoparticles were also produced from a mixture of [NiL(I)(2)] and N(2)H(4). The obtained Ni nanoparticles can be used for the catalytic addition of Ph(2)S(2) to 1-, 2- and 3-hexynes.

Amorphous and Crystalline GeTe Nanocrystals

AbstractA facile method for the synthesis of crystalline and amorphous GeTe nanoparticles (NPs) using bis((trimethylsilyl)amido)germanium(II), Ge[N(SiMe3)2]2, and elemental tellurium dispersed in tri‐n‐octylphosphine (TOP) is reported. As synthesized, crystalline particles exhibit narrow dispersity at smaller sizes and tend to grow into anisotropic shapes with increasing reaction time (growth). Furthermore, crystalline GeTe NPs possess rhombohedral symmetry with absorption band energies in near IR region (0.76–0.86 eV). Amorphous GeTe particles prepared at low temperatures are nearly spherical in morphology and display amorphous‐to‐crystalline phase transition at 209–237 °C depending on their primary particle size. Detailed investigation of the local structure of the amorphous GeTe using pair distribution function (PDF) method reveals that it is closely related to that of the pressure‐ and temperature‐stabilized orthorhombic GeTe.

Size-Tunable, Bright, and Stable PbS Quantum Dots: A Surface Chemistry Study

PbS Qdots are synthesized using PbCl2 and elemental sulfur as precursors. The available size range is significantly expanded using tri-n-octylphosphine (TOP), enabling the synthesis of monodisperse suspensions of Qdots with a mean size varying between 3 and 10 nm. The ligand composition and dynamics are investigated with nuclear magnetic resonance (NMR) spectroscopy. We show that the Qdots are passivated solely by highly dynamic OlAm ligands, even when TOP is employed during synthesis. In this respect, TOP is a compound strongly modifying the Qdot synthesis, without affecting the final Qdot surface chemistry. Next, the OlAm ligands are exchanged for oleic acid (OlAc). NMR data show that the OlAc ligands are tightly bound to the Qdot surface, with a coverage of 3.0±0.4 nm(-2). In addition, we demonstrate that they are bound as oleate ions. Combining this with the inorganic Qdot composition, we observe that charge-neutral Qdots are obtained when taking into account the charge of the stoichiometric PbS Qdot core, the surface excess of Pb ions, the surface-adsorbed Cl ions and the oleate ligands. The Qdot suspensions are stable under atmospheric conditions, showing no changes in the NMR and absorbance spectra for several weeks. Finally, we determine the photoluminescence quantum yield (PL QY) for OlAc-capped PbS Qdots, synthesized either with or without TOP. In both cases, they are highly luminescent, with PL QY values varying between 20 and 90%, depending on the Qdot size.

Facile synthesis of SERS active Ag nanoparticles in the presence of tri-n-octylphosphine sulfide

A facile and novel way was reported here for the synthesis of hydrophobic Ag nanoparticles (NPs), using AgNO 3, tri-n-octylphosphine (TOP) and sulfur (S) powder in process. TOP was used as solvent, reducing agent and stabilizer. S could chelate with excessive TOP to form trioctylphosphine sulfide (TOPS), which served as second capping agent. The hydrophobic Ag NPs could be transformed into hydrophilic state through ligand exchange. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 4-aminothiophenol (4-ATP) were obtained on the hydrophobic and hydrophilic Ag NPs modified substrates, indicating that the as-synthesized Ag NPs had great potential for high sensitive optical detection applications.

The structural evolution and diffusion during the chemical transformation from cobalt to cobalt phosphide nanoparticles

We report the structural evolution and the diffusion processes which occur during the phase transformation of nanoparticles (NPs), e-Co to Co2P to CoP, from a reaction with tri-n-octylphosphine (TOP). Extended X-ray absorption fine structure (EXAFS) investigations were used to elucidate the changes in the local structure of cobalt atoms which occur as the chemical transformation progresses. The lack of long-range order, spread in interatomic distances, and overall increase in mean-square disorder compared with bulk structure reveal the decrease in the NP’s structural order compared with bulk structure, which contributes to their deviation from bulk-like behavior. Results from EXAFS show both the Co2P and CoP phases contain excess Co. Results from EXAFS, transmission electron microscopy, X-ray diffraction, and density functional theory calculations reveal that the inward diffusion of phosphorus is more favorable at the beginning of the transformation from e-Co to Co2P by forming an amorphous Co-P shell, while retaining a crystalline cobalt core. When the major phase of the sample turns to Co2P, the diffusion processes reverse and cobalt atom out-diffusion is favored, leaving a hollow void, characteristic of the nanoscale Kirkendall effect. For the transformation from Co2P to CoP theory predicts an outward diffusion of cobalt while the anion lattice remains intact. In real samples, however, the Co-rich nanoparticles continue Kirkendall hollowing. Knowledge about the transformation method and structural properties provides a means to tailor the synthesis and composition of the NPs to facilitate their use in applications.

Controlled Synthesis and Characterization of ZnSe Quantum Dots

Adopting improved metal-organic "Green method," Colloidal ZnSe quantum dots were synthesized by using cheap and low toxic zinc oxide (ZnO) in an organic solvent system of 1-hexadecylamine (HDA), lauric acid (LA) and tri-n-octylphosphine (TOP). The effects of HDA dosage, injection temperature, growth temperature and time on the microstructure and optical properties of ZnSe were studied by means of X-Ray diffraction(XRD), transmission electron microscopy (TEM), spectrofluorometers and ultraviolet spectrophotometer, respectively. The results showed that ZnSe quantum dots with the best range of the size evolution were obtained under the condition of injection at 280 degrees C and growth at 240 degrees C by choosing the optimal parameters of ZnO:HDA:LA= 1:2.1:5.2 and TOPSe = 1 mol/L. Its size became larger and the emission peak shifted obviously to red with increasing the growth time. Meanwhile, the obtained ZnSe was of the wurtzite structure, had good uniformity and fluorescent characteristics.

Deposition and Characterization of CdSe Nanoparticles in Polymeric Materials

Cadmium selenide nanoparticles coated with zinc sulphide CdSe/ZnS were prepared using dual source method. The composites were fabricated by stabilizing chemically synthesized semiconductor CdSe/ZnS into Laurylmethacrylate (LMA) and ethyleneglycol dimethacrylate (EGDMA) matrices in the presence of tri-n-octylphosphine (TOP). CdSe/ZnS were dispersed in toluene as a compatible medium for the polymerization and cross-linking of poly Laurylmethacrylate (LMA) networks. Transparent, fluorescent and flexible nano composites (NCs) materials resulted. The nano size particles and polymer composites were characterized by XRD, TG-DTA, IR, TEM and SEM.

Exciton Recombination and Upconverted Photoluminescence in Colloidal CdSe Quantum Dots

We studied photoluminescence (PL) of colloidal CdSe quantum dots (QDs) synthesized by a single-step method using cadmium oxide (CdO) and tri-n-octylphosphine selenide (TOPSe) as the Cd and Se sources, respectively, and tri-n-octylphosphine (TOP) as the reaction medium and subsequently dispersed in hexane. The QDs were excited by a narrow-band incoherent cw light source with photon energies near or below the first absorption maximum of the sample, and the resulting luminescence was dispersed and recorded. In the PL spectra, we identified two displaced by ∼16−38 meV strongly overlapping components with excitation energy dependent intensities. We also investigated lifetimes of the nonresonant PL decay at various excitation and emission energies using a frequency-domain method and observed multiexponential decay with three lifetimes approximately equal to 11.5(1.0), 41(2), and 155(15) ns. The low-energy component with the full width at half-maximum (fwhm) ranging from 135−155 meV was assigned to the charged exciton emission correlating with the shortest lifetime. The narrower high-energy component with the fwhm ranging from 80−90 meV was attributed to the band edge exciton emission with the middle lifetime. Photoexcitation of the QD sample in the onset of the absorption tail yielded blue-shifted (upconverted) luminescence. The blue-shifted PL was determined to result from a single-photon excitation. Therefore, we claimed that the upconversion process was thermally assisted. Numerical modeling showed the blue shift to be consistent with room temperature thermal phonon distribution in the colloidal QDs.

Ligand-dependent particle size control of PbSe quantum dots

Colloidal solutions of monodisperse PbSe quantum dots (QDs) were synthesized by a hot solution chemical method from a reaction mixture of lead oleate and TOPSe (TOP: tri- n-octylphosphine). The synthesis was carried out at a fixed temperature (170 °C) and time, while the particle sizes of the PbSe QDs were controlled by using two different kinds of organic ligands with varied chain length. It was seen that the tuning of PbSe QDs are possible by using the proper molar ratio of the co-ligands, such as acetic acid or hexanoic acid, at a fixed reaction temperature and time, verified by TEM and XRD as well as NIR absorption analysis. The effects of different organic acids were studied and the role of additional organic acids might be due to the extent of ligand exchange efficiency between the Pb oleate and acetic/hexanoic acid in the initial stage, which is caused by the steric hindrance effects of the acids.