Synthesis of iron nanoparticles: Size effects, shape control and organisation

Hydrogenation of bis(ditrimethylsilyl)amido iron complex, [Fe{N(SiMe₃)₂}₂], provides iron nanoparticles (NPs) which have been stabilised either by an organic polymer matrix or mixtures of long chain acid and amine ligands leading respectively to spherical nanoparticles of 1.8 nm size or nanocubes with edges of 7.2 or 8.4 nm. The 1.8 nm size NPs are magnetically independent. Their magnetisation is shown to be identical to that of clusters of the same size prepared and measured in UHV conditions, i.e. strongly increased as compared to bulk value. These NPs have been structurally characterised and display an original structure different from the classical bcc and fcc structures encountered in bulk iron. On the reverse iron nanocubes display a bcc structure and magnetic properties similar to those of bulk iron within experimental errors, in agreement with their larger size. These cubes crystallise into 3D superstructures.     

Analytical characterization of CuInS(2) semiconductor material

Systematic analytical procedures have been developed for determination of the stoichiometry of CuInS(2) and estimation of trace elements, including dopants and impurities, in the material. Samples of CuInS(2) are digested in an oxidizing acid to ensure completely transformation into Cu(2+), In(3+) and SO(4)(2-) ions. The stoichiometry determination is made sequentially by controlled potential electro-deposition of copper, followed by its EDTA titration, titrimetric determination of indium and gravimetric determination of sulphate, in a single sample solution. The relative errors for the determination of Cu and In are found to be -0.08% and +0.11% respectively, fulfilling the requirement for accurate stoichiometry assessment; that for S is -0.66%, which though rather high is still acceptable. For the determination of trace elements in CuInS(2), multistage combined procedures are employed. Cu in the sample solution is removed by electro-deposition and In by extraction of HInBr(4) with isopropyl ether, then most of the trace elements are finally determined by atomic-absorption spectrometry, and the rest by neutron-activation analysis. All the steps involved in the procedures have been optimized by using radioisotopes as tracers. By the procedures developed, a wide range of trace elements in CuInS(2), down to submicrogram level, can be determined.     

Facile thermolysis synthesis of CuInS2 nanocrystals with tunable anisotropic shape and structure

Monodisperse CuInS(2) nanocrystals are produced by injecting mixed metal-oleate precursors into hot organic solvents containing the dissolved sulphur sources. A better understanding of the formation mechanism of CuInS(2) has enabled us to tailor anisotropic shapes in the form of triangular-pyramid, circular cone, and bullet-like rods with tunable crystal phases by varying the synthetic conditions.     

Alloyed (ZnS)(x) (CuInS(2) )(1-x) Semiconductor Nanorods: Synthesis, Bandgap Tuning and Photocatalytic Properties

Rod-like nanocrystals of the semiconductor alloy (ZnS)(x) (CuInS(2) )(1-x) (ZCIS) have been colloidally prepared by using a one-pot non-injection-based synthetic strategy. The ZCIS nanorods crystallize in the hexagonal wurtzite structure and display preferential growth in the direction of the c axis. The bandgap of these quarternary alloyed nanorods can be conveniently tuned by varying the ratio of ZnS to CuInS(2) . A non-linear relationship between the bandgap and the alloy composition is observed. The ZCIS nanorods are found to exhibit promising photocatalytic behaviour in visible-light-driven degradation of Rhodamine?B.     

Synthesis of CuInS2 Nanocubes by a Wet Chemical Process

Cube‐shaped CuInS₂ nanoparticles were successfully prepared through a simple low‐temperature solution route. Mercaptoacetic acid was used as capping agent. The product was characterized by means of X‐ray diffraction (XRD), energy dispersive analysis of X‐rays (EDAX), transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL). The CuInS₂ nanocubes obtained were of a chalcopyrite structure. The EDAX analysis shows that as‐synthesized CuInS₂ nanocubes were slightly Cu‐rich and nearly stoichiometric.     

Synthesis of CuInS2-ZnS alloyed nanocubes with high luminescence

CuInS(2)-ZnS alloyed nanocubes with high luminescence were synthesized through a solution-based diffusion method.     

Synthesis and dispersion of Ni(OH)2 platelet-like nanoparticles in water

Synthesis of nanometric platelet-like Ni(OH)2 particles is described. The role of several experimental parameters on the particle size is investigated. A colloidal dispersion of particles is produced by adsorbing ionizable organic ligands (trisodium citrate) on the particle surface. The stability of this colloidal dispersion and the particle charge density are determined for different citrate ions concentrations.     

Synthesis of TiO2 nanoparticles on the Au(111) surface

The growth of titanium oxide nanoparticles on reconstructed Au(111) was investigated by scanning tunneling microscopy and x-ray photoelectron spectroscopy. Ti was deposited by physical-vapor deposition at 300 K. Regular arrays of titanium nanoparticles form by preferential nucleation of Ti at the elbow sites of the herringbone reconstruction. The titanium oxide nanoclusters were synthesized by subsequent exposure to O(2) at 300 K. Two-and three-dimensional titanium oxide nanocrystallites form during annealing in the temperature range from 600 to 900 K. At the same time, the Au(111) surface assumes a serrated 110-oriented step-edge morphology suggesting step-edge pinning by titanium oxide nanoparticles. The oxidation state of the titanium oxide nanoparticles varies with annealing temperature. Specifically, annealing to 900 K results in the formation of stoichiometric TiO(2) nanocrystals as judged by the Ti(2p) binding energies measured in the x-ray photoelectron data. The nanodispersed TiO(2) on Au(111) is an ideal system to test the various models proposed for the enhanced catalytic reactivity of supported Au nanoparticles.     

Synthesis of SnS2/SnS fullerene-like nanoparticles: a superlattice with polyhedral shape

Tin disulfide pellets were laser ablated in an inert gas atmosphere, and closed cage fullerene-like (IF) nanoparticles were produced. The nanoparticles had various polyhedra and short tubular structures. Some of these forms contained a periodic pattern of fringes resulting in a superstructure. These patterns could be assigned to a superlattice created by periodic stacking of layered SnS(2) and SnS. Such superlattices are reminiscent of misfit layer compounds, which are known to form tubular morphologies. This mechanism adds up to the established mechanism for IF formation, namely, the annihilation of reactive dangling bonds at the periphery of the nanoparticles. Additionally, it suggests that one of the driving forces to form tubules in misfit compounds is the annihilation of dangling bonds at the rim of the layered structure.     

Synthesis of gold nanoparticles stabilized with di-(2-ethylhexyl)dithiophosphoric acid and tris(2-aminoethyl)amine

Methods for preparing gold nanoparticles (NPs) surface-stabilized with di-(2-ethylhexyl)dithiophosphoric acid (DTPA) and tris(2-aminoethyl)amine (TAEA), which endow the nanoparticles with hydrophobic and hydrophilic properties, are described. In the case of DTPA, Au-NPs are first synthesized with surfactant shells by means of reducing [AuCl₄]^? with hydrazine in inverted micelles of oxyethylated Triton N-42 in a low-polarity medium of decane; then, the micelles are destroyed by polar chloroform in the presence of DTPA, which has a great affinity to gold due to its sulfur donor atoms and substitutes for the surfactant on the surface of the nanoparticles. In preparing hydrophilic nanoparticles, [AuCl₄]^? is reduced with solid NaBH₄ directly in a nonaqueous solution of TAEA based on an ethanol and 2-propanol (3: 10) mixture. The nanoparticles are characterized by elemental analysis (for Au, C, H, N, and Na), X-ray powder diffraction, electronic absorption spectra, IR spectra, photon-correlation spectra, and transmission electron microscopy (TEM).     

Synthesis and characterization of CuInS2 single source precursors for chemical vapor deposition

A family of single source precursors, for the spray chemical vapor deposition (CVD) of chalcopyrite thin films (CuInS₂), has been synthesized in good yields (ca. 65%). Newly synthesized compounds include [{L}₂Cu(SR)₂In(SR)₂], (R=alkyl, aryl; L=neutral donor ligand). The use of the single source precursors provides an attractive alternative over conventionally used multi-source precursors, which are often toxic, air sensitive and pyrophoric. However, it is desirable that these thin films be processed on flexible polymer substrates such as Kapton^TM. Therefore, milder deposition temperatures are needed to maintain the structural integrity of the underlying polymer substrates. By selective manipulation of the steric and electronic properties of the precursor, milder processing temperatures may be employed, while mainting the desired stoichiometry of the deposited films. Elucidation of the structures have been confirmed by the use of NMR. Thermal analytical techniques, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), have been employed to determine thermal profiles of each candidate compound. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and chemical modification of magnetic nanoparticles covalently bound to polystyrene-SiCl2-poly(2-vinylpyridine)

The present article offers a new approach to create a multifunctional material based on magnetic nanoparticles, which can be dispersed in aqueous and organic media. The preparation of this material was performed by binding covalently polymer chains based on a reactive diblock-copolymer of the polystyrene-SiCl₂-poly(2-vinylpyridine) type, with average molecular weight per number (M_n) equal to 14,700 g/mol and a polydispersity index (PDI) less than 1.1, onto the surface of γ-Fe₂O₃ magnetic nanoparticles. The dichlorosilane moiety of the diblock-copolymer reacted with the  OH groups of the magnetic nanoparticles immobilizing the polymer chain onto its surface. This reaction was monitored by FTIR and the polymer grafting density was determined by TGA and BET. Dynamic light scattering revealed that the hydrodynamic diameter of the nanoparticles increased after immobilizing the polymer. Contact angle measurements demonstrated the ability of the hybrid material to interact with organic and aqueous media allowing its dispersion in solvents with different polarities. This property was used to prepare a magnetically active emulsion. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1668–1675, 2010     

Synthesis and curing of poly(glycidyl methacrylate) nanoparticles

Glycidyl‐functional polymer nanoparticles [poly(glycidyl methacrylate) (PGMA)] were fabricated with microemulsion polymerization. The successful fabrication of PGMA nanoparticles was confirmed by Fourier transform infrared spectroscopy and transmission electron microscopy (TEM). A TEM image showed that the average diameter of the PGMA nanoparticles was approximately 10–28 nm and was fairly monodisperse. As the surfactant concentration increased, the average size of the nanoparticles decreased and approached an asymptotic value. A significant reduction of the nanoparticle size to the nanometer scale led to an enhanced number of surface functionalities, which played an important role in the curing reaction. The PGMA nanoparticles were cured with a low‐temperature curing agent, diethylene triamine, to produce ultrafine thermoset nanoparticles. The low‐temperature curing process was performed below the glass‐transition temperature of PGMA to prevent the coagulation and deformation of the nanoparticles. A TEM image indicated that the cured PGMA nanoparticles did not exhibit interparticle aggregation and morphological transformation during curing. The average size of the cured PGMA nanoparticles was consistent with that of the pristine PGMA nanoparticles © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2258–2265, 2005     

Detection of ascorbic acid and folic acid based on water-soluble CuInS(2) quantum dots

In this paper, water-soluble CuInS(2) ternary quantum dots (QDs) modified by mercaptopropionic acid (MPA) were directly synthesized by hydrothermal method. Ascorbic acid (AA) can induce the fluorescence enhancement of MPA-capped CuInS(2) QDs and can be used for the detection of AA. Under the optimized conditions, the relationship between the fluorescence intensity of the CuInS(2) QDs and AA concentration was linear in the range of 0.25-200 μmol?L(-1). Most relevant molecules and physiological ions had no effect on the detection of AA. The fluorescence intensity of CuInS(2) QDs enhanced by a certain amount of AA could be reduced in the presence of folic acid (FA) and thus can be used for the detection of FA with the linear range of 0.2-100 μmol?L(-1). Compared with previous reports, the established approach utilized a simple, sensitive, and selective strategy to develop the QDs probe based on fluorescence enhancing and quenching phenomena without complicated immobilization.     

Synthesis and antimicrobial activity of arabinogalactan-stabilized selenium nanoparticles from sodium bis(2-phenylethyl)diselenophosphinate

Russian Chemical Bulletin - Water-soluble elemental selenium nanocomposites containing 0.8-3.9% Se were synthesized by oxidation of sodium bis(2-phenylethyl)diselenophosphinate in aqueous medium in...     

Mass spectrometric studies of the Decomposition and the Heat of Formation of CuInS2(s)

The equilibrium vaporization of CuInS₂(s) was studied by Knudsen cell mass spectrometric techniques in the temperature range 902—1110 K. Based on these and independent congruency studies, CuInS₂(s) decomposes under steady-state conditions according to the reaction 2CuInS₂(s) = Cu₂S(s) + In₂S(g) + S₂(g). During the initial transient period of the vaporization of CuInS₂, the ion intensities of In₂S⁺ and S₂⁺ change and assume steady-state values after some time. A second-law evaluation of intensity versus temperature data, obtained under steady-state conditions, yielded a value for the heat of the above decomposition reaction (2 moles of CuInS₂) of δH 630.9 ± 26 kJ. With this quantity and auxiliary thermochemical data, the enthalpy of formation of CuInS₂(s) was computed to be δH = ?221.7 ± 13 kJ/mol.     

Synthesis of ZnO and TiO2 nanoparticles

We report on the synthesis of ZnO and TiO₂ nanoparticles by solution-phase methods, with a particular focus on the influence of experimental parameters on the kinetics of nucleation and coarsening. The nucleation rate of ZnO from the reaction between ZnCl₂ and NaOH in ethanol was found to increase with increasing precursor concentration, while the coarsening rate is independent of precursor concentration up to a threshold concentration. The nucleation rate of ZnO from Zn(OOC-CH₃)₂ and NaOH in n-alkanols was found to decrease with decreasing chain length, which is explained by the increase of the dielectric constant of the solvent. Due to the larger solubility of ZnO, nucleation is significantly slower than that observed in the case of TiO₂. TiO₂ nanoparticles coarsen according to the Lifshitz-Slyozov-Wagner model for Ostwald ripening. We also show that using amorphous titania as a base material, pure anatase and brookite nanoparticles can be synthesized.     

Synthesis and characterization of Au102(p-MBA)44 nanoparticles

The synthesis of Au(102)(p-MBA)(44) nanoparticles on a preparative scale in high yield is described. Various analytical methods are shown to give results consistent with the composition and known structure of the particles, showing the preparation is essentially homogeneous, and attesting to the validity of the methods as well. Derivatization of the particles with proteins and DNA is demonstrated, and conditions are described for imaging individual particles by cryo-EM at low electron dose, close to focus, conditions optimal for recording high-resolution details.     

Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)

A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the A2+BB2' approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form th...