Hydrazine In Solution Research Articles

Identification of the Molecular Precursors for Hydrazine Solution Processed CuIn(Se,S)2 Films and Their Interactions

We investigate the molecular species present in hydrazine CuIn(Se,S)2 precursor solutions, their interactions, and phase formation in solution processed CuIn(Se,S)2 thin films through Raman spectroscopy. The reaction between Cu2S and sulfur yields [Cu6S4]2− ions, while [In2Se4]2− ions are formed by the reaction of In2Se3 with selenium within their respective solutions. Once combined to prepare a CuIn(Se,S)2 precursor solution, these two species appear to be bridged via newly formed In−S bonds. The creation of the In−S bonds in the CuIn(Se,S)2 precursor solution provides strong evidence for the mixing of copper, indium, sulfur, and selenium at a molecular level even prior to deposition. From this configuration, relatively little atomic diffusion is required to reach the chalcopyrite structure, which enables the formation of highly uniform polycrystalline CuIn(Se,S)2 films at relatively low temperatures.

Corrosion Test of 304 Stainless Steel in Hydrazine and Methanol Solutions at 320 .DEG.C under Gamma-Irradiation and Gamma Radiolysis of Hydrazine and Methanol

It has been pointed out that dissolved hydrogen is one of the key factors of PWSCC (primary water stress corrosion cracking) in the primary systems of pressurized water reactors. The authors consider that application of alternative reductant for hydrogen may mitigate PWSCC. The corrosion tests of 304 stainless steels in 2 mmol dm−3 methanol solution and 2 mmol dm−3 hydrazine solution at 320 °C were carried out under γ-ray irradiation, and the corrosion environment was evaluated. Electrochemical corrosion potential (ECP) of the stainless steels was measured during the immersion tests. The ECP values were −605 mV and −643 mV vs. SHE in 2 mmol dm−3 hydrazine solution and 2 mmol dm−3 methanol solution at 320 °C, respectively. After the immersion tests, oxide films formed on the stainless steel specimens were analyzed with scanning probe microscope and X-ray diffraction. It is concluded that from the ECP measurement and comparison with previous results corrosion environment under following conditions is similar: (1) DH 1.5 ppm without irradiation, (2) methanol 2.9 ppm without irradiation, (3) hydrazine 2 mmol dm−3 under γ-ray irradiation and (4) methanol 2 mmol dm−3 under γ-ray irradiation. During the immersion tests, the test waters were sampled several times, and analyzed, in order to understand radiolysis of the methanol solution and the hydrazine solution at 320 °C. Hydrazine is decomposed predominantly through thermal decomposition, and an ammonia molecule is formed from a hydrazine molecule. Formaldehyde and ethylene glycol were detected in the methanol solution. But, carboxylates were not detected. The present results do not demonstrate oxidation of methanol to CO or CO2 . It is pointed out that irradiation experiments of higher absorbed dose are necessary.Copyright © 2010 by ASME

Solution-based fabrication of ZnO/ZnSe heterostructure nanowire arrays for solar energy conversion

We report a method for synthesizing ZnO/ZnSe heterostructure nanowire arrays for use in photoelectrochemical (PEC) water splitting. The surfaces of ZnO nanowires immobilized on a conducting glass substrate were modified to form ZnO/ZnSe heterostructure nanowire arrays through a reaction with an aqueous sodium selenite and hydrazine solution. ZnO/ZnSe heterostructure nanowires with different morphologies were synthesized by varying solution concentrations and reaction times. The ZnO nanowire/ZnSe nanoparticle heterostructures (ZS1) were synthesized by a dissolution–recrystallization mechanism. At longer reaction times and higher solution concentrations, the nanostructure arrays transformed into ZnO nanowire/ZnSe nanosphere heterostructure arrays (ZS2) via Ostwald ripening. ZnO/ZnSe heterostructure arrays (ZS1 and ZS2) yielded higher photocurrents than the pristine ZnO nanowire arrays in a PEC water splitting test under AM 1.5G simulated solar light. The ZnO/ZnSe heterostructure array photoanodes exhibited absorption in the visible spectrum (<550 nm in wavelength) with a high incident-photon-to-current-conversion efficiency (IPCE) of up to 47% (ZS1) or 57% (ZS2) at 0.0 V vs. Ag/AgCl. The photoanode yielded a relatively high photocurrent density of 1.67 mA cm−2 (ZS1) or 2.35 mA cm−2 (ZS2) at 0.3 V compared to the ZnO nanowire arrays (0.125 mA cm−2). Structural differences between ZS1 and ZS2 yielded different PEC performances. A comparison to ZS2 revealed that ZS1 exhibited a higher photocurrent density under a low applied potential (from −0.78 V to −0.07 V) and a lower photocurrent density under a high applied potential (above −0.07 V).

Effects of Porous Alumina Support and Plating Time on Electroless Plating of Palladium Membrane

The present work was focused on the preparation of palladium alloy membranes and the effect of properties of ceramic support on the composited membrane morphology. Palladium-base membrane is known to have high selectivity and stability for hydrogen separation. In order to increase hydrogen permeation and separation factor, the membrane must be thinner and defect-free. Palladium membrane supported on a porous alumina prepared by electroless plating is the promising method to provide good hydrogen permeability. The alumina tube substrate was pre-seeded by immersing in the palladium acetate solution and followed by reduction in the alkaline hydrazine solution. After that, the deposition of palladium membrane could be achieved from the plating bath containing ethylenediamine tetraacetic acid (EDTA) stabilized palladium complex and hydrazine. The morphology of palladium film was observed to progress as a function of plating time and a dense layer membrane was available after plating for 3 h. The porosity of ceramic support exhibited an effect on the microstructure of deposited film such that the support with low porosity tended to achieve a defect free palladium membrane.

Parametric study of cost-effective synthesis of crystalline copper nanoparticles and their crystallographic characterization

Pure and high-crystalline copper nanoparticles were synthesized at room temperature by reduction of copper nitrate with hydrazine hydrate in cetyltrimethyl ammonium bromide (CTAB) solution without using any extra gases. A parametric study has been carried out in terms of hydrazine concentration, solution pH, and stirring. Pure copper nanoparticles without oxidation were obtained at 0.1–0.2 M N 2H 4 and pH = 10. The growth mechanism of various shaped copper nanoparticles is discussed based on structural analysis by transmission electron microscopy and selected area electron diffraction.

Synthesis of Zirconia with Nanoporous Structure by a Supercritical Carbon Dioxide Microemulsion Route

Supercritical carbon dioxide (scCO2) fluid as a green solvent for processing can markedly reduce the use of organic solvents. Nanoporous clusters of zirconia (ZrO2) were synthesized in a [Zr4+](aq)/scCO2 microemulsion using hydrazine solution as the precipitating agent, and the resulting nanostructures (surface area, morphology) under different reaction temperatures and pressures were determined by BET and TEM. The inter droplet separation of microemulsions increases with the reaction pressure at a fixed temperature, giving different networked nanostructures. The closed pore diameters were in the range of 5–150 nm (mesopores and macropores) at 17.3 MPa and 80°C.

A sensitive hydrazine electrochemical sensor based on electrodeposition of gold nanoparticles on choline film modified glassy carbon electrode

A highly sensitive hydrazine sensor was developed based on the electrodeposition of gold nanoparticles onto the choline film modified glassy carbon electrode (GNPs/Ch/GCE). The electrochemical experiments showed that the GNPs/Ch film exhibited a distinctly higher activity for the electro-oxidation of hydrazine than GNPs with 3.4-fold enhancement of peak current. The kinetic parameters such as the electron transfer coefficient ( α) and the rate of electron exchange ( k) for the oxidation of hydrazine were determined. The diffusion coefficient ( D) of hydrazine in solution was also calculated by chronoamperometry. The sensor exhibited two wide linear ranges of 5.0 × 10 −7–5.0 × 10 −4 and 5.0 × 10 −4–9.3 × 10 −3 M with the detection limit of 1.0 × 10 −7 M ( s/ n = 3). The proposed electrode presented excellent operational and storage stability for the determination of hydrazine. Moreover, the sensor showed outstanding sensitivity, selectivity and reproducibility properties. All the results indicated a good potential application of this sensor in the detection of hydrazine.

Macro and meso porous polymeric materials from miscible polysulfone/polyimide blends by chemical decomposition of polyimides

Novel macro and meso porous polysulfone materials were prepared from miscible blends of polysulfones with a phenylindane containing polyimide by selective chemical decomposition of the polyimide phase using a dilute hydrazine or tetraammonium hydroxide solution in methanol. It was found that the pore size of the material is affected by the backbone structure of the polysulfone selected. The compatibility between the polysulfones and the polyimide is influenced by the polysulfone structure. This in turn affects the pore size and the pore size distribution of the final porous material. Polyether sulfone was found to form most compatible blends that in turn leads to a porous material with the smallest pore size, a meso porous material. The meso porous polyether sulfones are transparent films, with uniform pore sizes in the range of 30 nm, while bisphenol A polysulfone based porous materials are opaque with pore sizes in the range of 200 nm.

Study on the effect of surfactants on morphologies of trigonal selenium in microfluidic reactor

The influence of the surfactants on the morphologies of trigonal selenium (t-Se) submicrostructures was studied in a two-step microfluidic system, which is composed of a glass microchip for preparing spherical amorphous selenium (a-Se) colloids coupled with a poly(methyl methacrylate) microchip for transferring a-Se into its t-Se seeds under sonication. The selenious acid containing surfactants and hydrazine solutions were delivered through the two-inlets of the glass microfluidic chip. Submicro-rods, -wires as well as -tubes of t-Se were obtained by simply varying the coexisted surfactants. The as-synthesized products were characterized by powder X-ray diffraction (XRD), Raman spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED).

Large-Area Chemically Modified Graphene Films: Electrophoretic Deposition and Characterization by Soft X-ray Absorption Spectroscopy

A facile, rapid, and scalable electrophoretic deposition approach is developed for the fabrication of large-area chemically derived graphene films on conductive substrates based on the electrophoretic deposition of graphene oxide and reduced graphene oxide components. Two distinctive approaches for fabricating conformal graphene films are developed. In the first approach, graphene oxide sheets are electrophoretically deposited from an aqueous solution after the oxidation of graphite to graphite oxide and the subsequent exfoliation of graphite oxide to graphene oxide. Next, the graphene oxide films are reduced via dip-coating in an aqueous solution of hydrazine. In the second approach, graphene oxide is reduced to graphene nanosheets in a strongly alkaline solution and the reduced graphene sheets are directly electrophoretically deposited onto conductive substrates. The film thickness can be modified by the deposition time and the obtained films span several square millimeters in area. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is used to study the surface chemistry, electronic band structure, and degree of alignment of the electrophoretically deposited films. Polarized NEXAFS measurements verify the presence of epoxide surface functionalities on the graphene basal planes and indicate significant recovery of extended π-bonded networks upon defunctionalization by hydrazine treatment. These measurements further indicate significantly improved alignment of the graphene sheet components of the films parallel to the substrate surface when defunctionalization is performed prior to electrophoretic deposition.

The affects of membrane on the cell performance when using alkaline borohydride–hydrazine solutions as the fuel

The cell performance and the polarization behavior of the fuel cell using alkaline NaBH 4–N 2H 4 solutions as the fuel were investigated. It was found that the use of different membrane: anion exchange membrane (AEM) or cation exchange membrane (CEM) would influence the cell performance and cathode polarization behavior. The direct borohydride fuel cell (DBFC) using CEM gave a higher power density than that using AEM, but the direct hydrazine fuel cell (DHFC) using CEM gave a lower power density compared with the DHFC using AEM. In the DBFCs using CEM, N 2H 4 addition in alkaline NaBH 4 solution improved the cell performance but it did not make any difference when adding more N 2H 4. On the other hand, in the DBFCs using AEM, cell performance was improved with increasing the amount of N 2H 4 in the anolyte.

Solvothermal Synthesis and Characterization of Fe3O4 and γ-Fe2O3 Nanoplates

γ-Fe2O3 nanoplates were prepared by a simple solution process and could be transformed to Fe3O4 nanoplates while keeping the size and morphology unchanged after reduction in hydrazine solution. The crystal structure and surface organic groups of the nanoplates were characterized in detail. The nanoplates exhibited good dispersibility in polar solvents except water and strong dipolar interactions, which favored the formation of one-dimensional chainlike structure. The poly(vinylpyrrolidone) molecules in this system played a key role for the growth of nanoplates, and it was supposed that the formation of nanoplates was a kinetically controlled process. The γ-Fe2O3 and Fe3O4 nanoplates with strong dipolar interactions are ferromagnetic at room temperature.

In situ reduction of Fe(iii) into Fe(ii): an example of post-crystallisation transformation

Upon exposing crystals made of a combination of an amidinium based dication and [Fe(III)(CN)(6)](3?) anion to a hydroalcoholic solution of hydrazine and KCl, the reduction of Fe(iii) to Fe(ii) with concomitant incorporation of K(+) cation takes place in the crystalline phase.

The synthesis of nickel nanoparticles with controlled morphology and SiO 2/Ni core-shell structures

The magnetic nanopowders can be potentially applied in wide range of fields such as magnetic storage, magnetic fluid, medical diagnosis, conducting paints, rechargeable batteries, optoelectronics, magnetic recording media, drug delivery system and catalysis. They have attracted interest in the past decade and have also been studied extensively because of their size- and shape-dependent physical-chemical and magnetic properties for applications in various useful technologies. In this work, we present our experimental results on the preparation of nanosized Ni nanoparticles with different shapes by using a wet chemical solution route. Ni nanoparticles were prepared by reducing a Ni-complex formed between nickel-acetate and hydrazine solution under basic condition. Then through the control of reaction temperature and ageing time, nanosized Ni particles with different morphologies could be formed. The morphology and sizes of synthesized nanostructures were studied by scanning electron microscopy (SEM). Structural properties of nanoparticles were examined by X-ray diffraction. We also report the core-shell structures of micro-composites of silica-nickel (SiO 2/Ni). The composite core-shell structures were formed by the control of the surface charges of particles in aqueous solutions. A specific composite (SiO 2/Ni) can be produced by controlling the surface charge, the pH and the molar ratio of the components. Core-shell structures are stable at room temperature.

Effects of process parameters on the synthesis of palladium membranes

In this study, palladium film plating was carried out on porous glass supports using the electroless plating technique. This technique was applied to study the effects of bath temperature and reducing agent concentration on the amount and the structure of palladium plated. Hydrazine concentration was fixed at 10 ml/L in the baths using 1 M hydrazine solution while the temperature was changed between 25 and 50 °C. The total mass gain and Pd/Si ratio (wt/wt%) on the surface were obtained as 7.76 mg/cm 2 and 68.7 in a bath temperature of 35 °C, respectively. With the help of LM microscope analysis, thickness of the membrane prepared at this temperature was determined as 31 μm. In the studies in which the bath temperature was examined as a parameter, the minimum total mass gain was obtained in a plating bath temperature of 43 °C. In the second part of this study, in order to study the concentration effect of hydrazine, hydrazine concentration was increased to 15 and 20 ml/L at a bath temperature of 43 °C. It was shown that as a result of increasing the hydrazine concentration from 10 ml/L to 15 ml/L, total mass gain increased more than twice and a denser plating was obtained. On the contrary to expectations, a result less successful than in the study of 10 ml/L concentration was obtained through increasing hydrazine concentration to 20 ml/L. This study showed that bath temperature of 25 °C was too low to carry out effectively autocatalytic reaction on the activated surface. Plating bath decomposed in plating studies performed at 43 °C and 50 °C. In the studies where hydrazine concentrations were examined as a parameter, it was observed that the stability of the bath could not be maintained in each of the three baths throughout the plating time. The highest decomposition rate was also predicted for the study carried out at a hydrazine concentration of 20 ml/L. Decomposition seen at high temperatures and high hydrazine concentrations was explained as a consequence of insufficient EDTA concentrations in plating baths.

Preparation and physical/electrochemical characterization of Pt/poly(vinylferrocenium) electrocatalyst for methanol oxidation

Preparation and characterization of a platinum (Pt)-based catalyst using a redox polymer, poly(vinylferrocenium) (PVF +), as the support material was described. Pt was obtained from aqueous solution of K 2PtCl 4 in the complex form. Pt particles were reduced by chemical and electrochemical means. Chemical reduction was performed using aqueous hydrazine solution and electrochemical reduction was carried out in H 2SO 4 solution. The Pt/PVF + catalyst system showed catalytic activity towards methanol oxidation. Cyclic voltammetry was used for the electrochemical characterization of the catalyst system. Scanning electron microscopy (SEM) images and energy dispersive X-ray spectrum (EDS) of the catalyst system were also recorded. The system was tested in a single fuel cell configuration at ambient temperature and atmospheric pressure. The open circuit voltage (OCV) was 680 mV for the system and the maximum power density was 0.31 mW cm −2 at a current density of 0.63 mA cm −2. Catalytic activity of Pt/PVF + system towards methanol oxidation was comparable with the related catalysts in the literature.

Effects of NaOH addition on performance of the direct hydrazine fuel cell

In this work, we suggested a figuration of the direct hydrazine fuel cell (DHFC) using non-precious metals as the anode catalyst, ion exchange membranes as the electrolyte and alkaline hydrazine solutions as the fuel. NaOH addition in the anolyte effectively improved the open circuit voltage and the performance of the DHFC. A power density of 84 mW cm −2 has been achieved when operating the cell at room temperature. It was found that the cell performance was mainly influenced by anode polarization when using alkaline N 2H 4 solutions with low NaOH concentrations. However, when using alkaline N 2H 4 solutions with high NaOH concentrations as the fuel, the cell performance was mainly influenced by cathode polarization.

Structural, Optical, and Electrical Properties of PbSe Nanocrystal Solids Treated Thermally or with Simple Amines

We describe the structural, optical, and electrical properties of films of spin-cast, oleate-capped PbSe nanocrystals that are treated thermally or chemically in solutions of hydrazine, methylamine, or pyridine to produce electronically coupled nanocrystal solids. Postdeposition heat treatments trigger nanocrystal sintering at approximately 200 degrees C, before a substantial fraction of the oleate capping group evaporates or pyrolyzes. The sintered nanocrystal films have a large hole density and are highly conductive. Most of the amine treatments preserve the size of the nanocrystals and remove much of the oleate, decreasing the separation between nanocrystals and yielding conductive films. X-ray scattering, X-ray photoelectron and optical spectroscopy, electron microscopy, and field-effect transistor electrical measurements are used to compare the impact of these chemical treatments. We find that the concentration of amines adsorbed to the NC films is very low in all cases. Treatments in hydrazine in acetonitrile remove only 2-7% of the oleate yet result in high-mobility n-type transistors. In contrast, ethanol-based hydrazine treatments remove 85-90% of the original oleate load. Treatments in pure ethanol strip 20% of the oleate and create conductive p-type transistors. Methylamine- and pyridine-treated films are also p-type. These chemically treated films oxidize rapidly in air to yield, after short air exposures, highly conductive p-type nanocrystal solids. Our results aid in the rational development of solar cells based on colloidal nanocrystal films.

Combined Newborn Screening for Succinylacetone, Amino Acids, and Acylcarnitines in Dried Blood Spots

Tyrosinemia type I (TYR 1) is a disorder causing early death if left untreated. Newborn screening (NBS) for this condition is problematic because determination of the diagnostic marker, succinylacetone (SUAC), requires a separate first-tier or only partially effective second-tier analysis based on tyrosine concentration. To overcome these problems, we developed a new assay that simultaneously determines acylcarnitines (AC), amino acids (AA), and SUAC in dried blood spots (DBS) by flow injection tandem mass spectrometry (MS/MS). We extracted 3/16-inch DBS punches with 300 microL methanol containing AA and AC stable isotope-labeled internal standards. This extract was derivatized with butanol-HCl. In parallel, we extracted SUAC from the residual filter paper with 100 microL of a 15 mmol/L hydrazine solution containing the internal standard 13C5-SUAC. We combined the derivatized aliquots in acetonitrile for MS/MS analysis of AC and AA with additional SRM experiments for SUAC (m/z 155-137) and 13C5-SUAC (m/z 160-142). Analysis time was 1.2 min. SUAC was increased in retrospectively analyzed NBS samples of 11 TYR 1 patients (length of storage, 52 months to 1 week; SUAC range, 13-81 micromol/L), with Tyr concentrations ranging from 65 to 293 micromol/L in the original NBS analysis. The mean concentration of SUAC in 13 521 control DBS was 1.25 micromol/L. The inclusion of SUAC analysis into routine analysis of AC and AA allows for rapid and cost-effective screening for TYR 1 with no tangible risk of false-negative results.

The inclusion of succinylacetone as marker for tyrosinemia type I in expanded newborn screening programs

In expanded newborn screening programs by liquid chromatography/tandem mass spectrometry false negatives for tyrosinemia type I are a significant problem. We describe a method for inclusion of succinylacetone in order to avoid false negatives. We studied spots from 13,000 neonates born in Tuscany (January-May 2007) and ten spots from six patients with tyrosinemia type I. The traditional screening method was modified by adding dioxooctanoid acid (or 13C2-succinylacetone) as an internal standard to the methanolic solution of deuterated acylcarnitines and amino acids. A hydrazine solution was added to the mixture. The times of extraction, butylation and drying were only slightly prolonged. Specific multiple reaction monitoring for derivatized and labelled succinylacetone and dioxooctanoic acid was carried out. The assays were linear up to 100 micromol/L for succinylacetone. Intra- and inter-day imprecision data were in the range of 1.34% to 7.09% and 3.50% to 4.49%. Limits of detection and of quantification were 0.2 micromol/L and 0.4 micromol/L, respectively. Recovery ranged from 97.02% to 100.29%. Succinylacetone levels in samples from unaffected neonates were very close to the detection limit. Of the 46 recalls, eight (17.4%) were for abnormal tyrosine levels and all these cases had succinylacetone levels within the normal range (<2.4 micromol/L). In ten spots from six affected patients succinylacetone values ranged from 3.3 to 35.0 micromol/L. Including succinylacetone in newborn screening programs for amino acids and acylcarnitines avoids false-negative results for tyrosinemia type I. Newborn screening laboratories should consider implementing these modifications.