Acetylacetonate Salts Research Articles

Structural and Thermomagnetic Properties of Gallium Nanoferrites and Their Influence on Cells In Vitro.

Magnetite and gallium substituted cuboferrites with a composition of GaxFe3-xO4 (0 ≤ x ≤ 1.4) were fabricated by thermal decomposition from acetylacetonate salts. The effect of Ga3+ cation substitution on the structural and thermomagnetic behavior of 4-12 nm sized core-shell particles was explored by X-ray and neutron diffraction, small angle neutron scattering, transmission electron microscopy, Mössbauer spectroscopy, and calorimetric measurements. Superparamagnetic (SPM) behavior and thermal capacity against increasing gallium concentration in nanoferrites were revealed. The highest heat capacity typical for Fe3O4@Ga0.6Fe2.4O4 and Ga0.6Fe2.4O4@Fe3O4 is accompanied by a slight stimulation of fibroblast culture growth and inhibition of HeLa cell growth. The observed effect is concentration dependent in the range of 0.01-0.1 mg/mL and particles of Ga0.6Fe2.4O4@Fe3O4 design have a greater effect on cells. Observed magnetic heat properties, as well as interactions with tumor and healthy cells, provide a basis for further biomedical research to use the proposed nanoparticle systems in cancer thermotherapy (magnetic hyperthermia).

Homogeneous Nanoparticles of Multimetallic Phosphides via Precursor Tuning: Ternary and Quaternary M2P Phases (M = Fe, Co, Ni).

Transition metal phosphides (TMPs) are a highly investigated class of nanomaterials due to their unique magnetic and catalytic properties. Although robust and reproducible synthetic routes to narrow polydispersity monometallic phosphide nanoparticles (M2P; M = Fe, Co, Ni) have been established, the preparation of multimetallic nanoparticle phases (M2-x M' x P; M, M' = Fe, Co, Ni) remains a significant challenge. Colloidal syntheses employ zero-valent metal carbonyl or multivalent acetylacetonate salt precursors in combination with trioctylphosphine as the source of phosphorus, oleylamine as the reducing agent, and additional solvents such as octadecene or octyl ether as "noncoordinating" cosolvents. Understanding how these different metal precursors behave in identical reaction environments is critical to assessing the role the relative reactivity of the metal precursor plays in synthesizing complex, homogeneous multimetallic TMP phases. In this study, phosphorus incorporation as a function of temperature and time was evaluated to probe how the relative rate of phosphidation of organometallic carbonyl and acetylacetonate salt precursors influences the homogeneous formation of bimetallic phosphide phases (M2-x M' x P; M, M' = Fe, Co, Ni). From the relative rate of phosphidation studies, we found that where reactivity with TOP for the various metal precursors differs significantly, prealloying steps are necessary to isolate the desired bimetallic phosphide phase. These insights were then translated to establish streamlined synthetic protocols for the formation of new trimetallic Fe2-x-y Ni x Co y P phases.

In-situ growth of iron nanoparticles on porous carbon nanofibers for structural high-performance lithium metal anode

Lithium metal anodes have attracted increasing attention in recent years. However, there are still significant challenges in the electrochemical cycle of lithium metals, including the growth of lithium dendrites, the formation of "dead lithium" layers, and unrestricted volume expansion. To solve these problems, using inexpensive acetylacetonate salt, polyacrylonitrile, and polymethyl methacrylate as raw materials, a 3D porous carbon nanofiber scaffold decorated with iron nanoparticles is reasonably designed by novel and unique in-situ growth method, without hazardous atmosphere, expensive catalyst deposition, and additional carbon sources. Notably, the obtained iron-doped 3D porous fibers can be used as lithium metal anode framework with low lithium deposition overpotential and long cycling stability under various current densities. The porous host structure can adapt to the inherent volume expansion and the transmission of lithium ions in the process of lithium plating/stripping, thereby improving the cycling stability. Density functional theory calculations indicate that carbon nanofibers decorated with Fe nanoparticles are more likely to absorb lithium atoms, resulting in more uniform lithium deposition. The present work provides a low-cost and scalable strategy for constructing 3D structural high-efficiency lithium metal anode, and opens new horizons for the research of lithium metal batteries and even other metal batteries.

Synthesis, spectral characterization, crystal structures, biological activities, theoretical calculations and substitution effect of salicylidene ligand on the nature of mono and dinuclear Zn(II) Schiff base complexes

Two new zinc(II) Schiff base complexes (Z1 and Z2) are prepared by treating ONNO tetradentate Schiff base ligands (H2L1 = [6,6′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol)] and H2L2 = [2,2′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))bis(4-methoxyphenol)]) with acetylacetonate salt of zinc. The synthesized Schiff base ligands and their respective zinc(II) complexes were characterized by elemental analysis (CHN) and various spectroscopic techniques like FT-IR and 1H NMR. The single crystal X-ray structures of Z1 and Z2 show the effect of salicylidene ligand on the nature of mono and dinuclear Zn(II) Schiff base complexes. In Z1 complex, a square pyramidal geometry is adapted by the complex, supported by the ONNO donor atoms of the tetradentate Schiff base and a coordinated water molecule. Structural analysis of Z2 complex revealed that the compound is a centrosymmetric dimer in which the five coordinated Zn(II) atoms are linked to the opposite metal center by making μ-phenoxo bridges through one of the phenolic oxygen atoms of Schiff base ligands. The nature of various kinds of non-covalent interactions present among the sample molecules was also investigated by using QTAIM and NCI calculations. The theoretical calculations were performed by DFT using the B3LYP/Def2-TZVP level of theory, which indicated that the intended outcomes are in compliance with the actual consequences. Furthermore, the antibacterial potential of the Schiff base ligands and their corresponding zinc complexes was measured by testing them against two Gram-positive (Staphylococcus aureus and Bacillus cereus) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The agar well diffusion method and poisoned media technique were used for screening of bacterial and fungal species, respectively. According to the results of the zone of inhibition assessments, metal complexes have comparatively more inhibition potential relative to free ligands.

Magnetic Properties of Bi-Magnetic Core/Shell Nanoparticles: The Case of Thin Shells

Bi-magnetic core/shell nanoparticles were synthesized by a two-step high-temperature decomposition method of metal acetylacetonate salts. Transmission electron microscopy confirmed the formation of an ultrathin shell (~0.6 nm) of NiO and NiFe2O4 around the magnetically hard 8 nm CoFe2O4 core nanoparticle. Magnetization measurements showed an increase in the coercivity of the single-phase CoFe2O4 seed nanoparticles from ~1.2 T to ~1.5 T and to ~2.0 T for CoFe2O4/NiFe2O4 and CoFe2O4/NiO, respectively. The NiFe2O4 shell also increases the magnetic volume of particles and the dipolar interparticle interactions. In contrast, the NiO shell prevents such interactions and keeps the magnetic volume almost unchanged.

Binuclear Zn(II) Schiff base complexes: Synthesis, spectral characterization, theoretical studies and antimicrobial investigations

Binuclear zinc(II) Schiff base complexes were synthesized through the reaction of ONNO tetradentate Schiff base ligands derived from the condensation of 2,2-dimethyl-1,3-propanediamine and 5-chlorosalicylaldehyde or 5-bromosalicylaldehyde with zinc acetylacetonate salt. The structures of synthesized products were explored spectroscopically through the FT-IR, 1H NMR and elemental analysis. Structural analysis of the complexes revealed that the compound is a centrosymmetric dimer in which the five coordinated Zn(II) atoms are linked to the opposite metal center by making μ-phenoxo bridges through one of the phenolic oxygen atoms of Schiff base ligands. The nature and types of non-covalent interactions present among the sample molecules were also investigated by using the quantum theory of atoms in molecules and non-covalent interactions calculations. The theoretical calculations, performed by density functional theory using the B3LYP/Def2-TZVP level of theory, direct that the intended outcomes are in compliance with the actual consequences. Furthermore, from antimicrobial screenings it was revealed that the zinc complexes are more active as compared to the ligands.

Novel oxovanadium and dioxomolybdenum complexes of tridentate ONO-donor Schiff base ligand: Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity for the selective oxidation of benzylic alcohols

Two new oxovanadium and dioxomolybdenum Schiff base complexes, [VvO(L)(OCH3)(CH3OH)] and [MoVIO2(L)(CH2CH3OH)], were synthesized by treating an ONO-donor type Schiff base ligand (H2L) derived by condensation of 5-nitrosalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum, [VO(acac)2 and MoO2(acac)2], respectively. The synthesized ligand and complexes were characterized by various spectroscopic techniques like FT-IR, multinuclear (1H, 13C) NMR, elemental analysis and the most authentic single crystal X-ray diffraction analysis. In both complexes the geometry around the central metal ions was distorted octahedral as revealed by the data collected from diffraction studies. Theoretical calculation of the synthesized compounds were carried out by DFT as well as TD-DFT using B3LYP method by employing the Def2-TZVP basis set. The findings of theoretical data indicated that the calculated results are in accordance with the experimental findings. Moreover, the catalytic efficiencies of both complexes were investigated by oxidizing the benzylic alcohols in the presence of urea hydrogen peroxide (UHP) in acetonitrile.

Oxovanadium and dioxomolybdenum complexes: synthesis, crystal structure, spectroscopic characterization and applications as homogeneous catalysts in sulfoxidation

New oxovanadium and dioxomolybdenum Schiff base complexes, [VO(L)(OCH3)] n and [MoO2(L)(CH3OH)], were synthesized by treating an ONO donor Schiff base (H2L) derived by condensation of 3-ethoxysalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum (VO(acac)2 and MoO2(acac)2), respectively. The synthesized ligand and complexes were characterized by FTIR, multinuclear (1H, 13C) NMR, elemental and single crystal X-ray diffraction analysis. In both complexes, the geometry around the central metal ions was distorted octahedral as revealed by diffraction studies. Theoretical calculations of the synthesized compounds were carried out by DFT at B3LYP/Def2-TZVP level of theory, which showed good correlation with the experimental results. Moreover, the catalytic efficiency of both complexes was investigated by oxidizing aryl and alkyl sulfides in the presence of 30% H2O2 in ethanol.

Synthesis, characterization, crystal structures, Hirshfeld surface analysis, DFT computational studies and catalytic activity of novel oxovanadium and dioxomolybdenum complexes with ONO tridentate Schiff base ligand

For the first time, two new oxovanadium and dioxomolybdenum Schiff base complexes, VOL(OMe) and MoO2L, were synthesized through the reaction of a ONO tridentate Schiff base ligand (H2L) derived from the condensation of 5-bromosalicylaldehyde and nicotinic hydrazide with oxo and dioxo acetylacetonate salts of vanadium and molybdenum, [VO(acac)2 and MoO2(acac)2], respectively. The synthesized ligand and complexes were characterized by various spectroscopic techniques like FT-IR, 1H NMR, 13C NMR, elemental analysis (CHN) and the most authentic single crystal X-ray diffraction analysis (SC-XRD). The geometry around the central metal ion in MoO2L was distorted octahedral as revealed by the data collected from diffraction studies. Non-covalent interactions that are responsible for crystal packing are explored by Hirshfeld surface analysis. Theoretical calculations of the synthesized compounds, carried out by DFT at B3LYP/Def2-TZVP level of theory, indicated that the calculated results are in agreement with the experimental findings. Moreover, the catalytic activities of both complexes were investigated for the selective oxidation of benzylic alcohols using urea hydrogen peroxide (UHP) in acetonitrile.

In-situ fabrication of carbon-metal fabrics as freestanding electrodes for high-performance flexible energy storage devices

Hierarchical 1D carbon structures are attractive due to their mechanical, chemical and electrochemical properties however the synthesis of these materials can be costly and complicated. Here, through the combination of inexpensive acetylacetonate salts of Ni, Co and Fe with a solution of polyacrylonitrile (PAN), self-assembling carbon-metal fabrics (CMFs) containing unique 1D hierarchical structures can be created via easy and low-cost heat treatment without the need for costly catalyst deposition nor a dangerous hydrocarbon atmosphere. Microscopic and spectroscopic measurements show that the CMFs form through the decomposition and exsolution of metal nanoparticle domains which then catalyze the formation of carbon nanotubes through the decomposition by-products of the PAN. These weakly bound nanoparticles form structures similar to trichomes found in plants, with a combination of base-growth, tip-growth and peapod-like structures, where the metal domain exhibits a core(graphitic)-shell(disorder) carbon coating where the thickness is in-line with the metal-carbon binding energy. These CMFs were used as a cathode in a flexible zinc-air battery which exhibited superior performance to pure electrospun carbon fibers, with their metallic nanoparticle domains acting as bifunctional catalysts. This work therefore unlocks a potentially new category of composite metal-carbon fiber based structures for energy storage applications and beyond.

Immobilization of Co, Mn, Ni and Fe oxide co-catalysts on TiO2 for photocatalytic water splitting reactions

Here we report a systematic study of Co, Mn, Ni and Fe oxides as co-catalysts for HER and OER that were prepared by wet impregnation of the corresponding metal acetylacetonate salts onto a model TiO2 substrate.

Preparation Condition Optimization and Characterization of PtNi/C Octahedral Nanocrystal Catalyst for ORR

The proton exchange membrane fuel cells (PEMFCs) are expected to be one of the most suitable power sources for electric vehicles to replace the traditional energy,1 but its commercialization is restricted by some problems, such as high cost, low durability and inadequate facilities and so on.2 Among these problems, the high cost, unsatisfactory activity and durability of Pt catalyst as the key part in fuel cells become particularly important.3 It is one of promising solutions to design and prepare low Pt loading catalysts4 with high efficiency and low cost. Recently, it is found that the (111) facets possess the highest oxygen reduction reaction (ORR) activity in the three low index facets of Pt alloys,5 and thus Pt-based octahedral catalysts with maximal (111) surface area have been paid more attention. However, in methods commonly employed, the capping agents difficult to remove not only block the active sites but also hinder the electron transfer between catalyst and support. Therefore, surfactant-free method is employed, and the growth of specific facet is synergistically regulated by suitable organic reducing agent and organic ligands of precursors to replace capping agents.6 The reaction conditions have important influence on the crystal growth process, crystal size, bulk and surface atom arrangement. In this work, impacts of reaction temperature, reaction time and ratio of metal elements on the formation of PtNi octahedral nanocrystals were investigated to optimize preparation conditions. The results demonstrate that reaction temperatures can affect crystallization rates, and lower temperature leads to excessively slow reduction and crystallization rate, which will result in small particles and incomplete (111) facet growth, whereas a higher temperature will cause a faster crystallization rate and larger particles, which will result in loss of active sites and decreased ORR performance. The influence of reaction time on electrochemical performance mainly depends on the synergistic effect between crystal growth and metal atom migration caused by concentration gradients. For one thing, crystal sizes are increased with the reaction time prolonged, which will result in the decrease of active area; for another, the atom concentration gradients resulted from different electrochemical deposition potentials impel Pt atom to migrate towards the surface, which is beneficial to the increase of active sites. The mechanism is more complex for impact of different atom ratios. We suggest that the ORR activities of PtNi octahedral nanocrystals with different Pt/Ni atom ratios are determined by the delicate balance between the thickness of Pt surface skin, the Ni content near the surface and the remaining (111) facets. Accordingly, reaction temperature of 140 °C, reaction time of 42 h and Pt/Ni atom ratio of 1: 1 were selected to prepare the PtNi/C octahedral nanocrystal catalyst in order to ensure optimal ORR performance. Under the optimized reaction conditions, PtNi/C octahedral nanocrystal catalyst with highly active (111) facets as surface was successfully prepared by a facile one-pot surfactant-free solvothermal method using acetylacetonate salts as precursors and dimethylfomamide (DMF) as reducing agent, and it exhibits well-defined structure and enhanced ORR performance compared with commercial Pt/C catalyst. Its mass activity and specific activity are 224.5 mA mgPt -1 and 618.5 μA cmPt -2, which are about 2.6 times and 3.8 times of Pt/C (Johnson Matthey, JM), respectively. The electrochemically active surface areas (ECSAs) of Pt/C (JM) decrease from 53.2 m2 gPt -1 to 32.5 m2 gPt -1 after 2000 cycles accelerated durability testing (ADT), indicating a loss of 38.9%, whereas the attenuation rate in ECSA of PtNi/C octahedral nanocrystal catalyst is only 23.1%. The mass activity of Pt/C (JM) at 0.9 V vs. RHE is reduced from 86.4 mA mgPt -1 to 30.6 mA mgPt -1 after durability test, and the attenuation rate is up to 64.6%; nevertheless, the mass activity of PtNi/C octahedral nanocrystal catalyst is dropped by 46.1%, and its mass activity after 2000 cycles is yet higher than the initial value of Pt/C (JM). Our work provides some valuable insights in the preparation condition optimization of PtNi octahedral catalyst, and has a certain guiding significance for further research on the preparation of shape-selective catalysts.

HYDRAZIDE SCHIFF BASES OF ACETYLACETONATE METAL COMPLEXES: SYNTHESIS, SPECTROSCOPIC AND BIOLOGICAL STUDIES

Objective: The study was focused on the synthesis and spectroscopic studies of metal acetylacetonates and their complexes using bidentate Schiff-base ligands (NO), evaluation of their in-vitro antibacterial potentials against pathogenic microorganism.Methods: Acetylacetonate salts of Cobalt(II), Manganese(II) and Magnesium(II) were prepared by reacting their metal hydroxides with acetylacetone. The metal complexes of N'-{(E)-[4-(diethylamino)-2-hydroxyphenyl]methylidene}-4-nitrobenzohydrazide (HL1), N'-{(E)-[4-(diethylamino)-2-hydroxyphenyl]methylidene}-4-methoxybenzohydrazide (HL2) obtained from the condensation reaction of 4-(diethylamino)-2-hydroxybenzaldehyde and 4-nitrobenzohydrazide/ or 4-methoxybenzohydrazide. The synthesized compounds were characterized by fourier transform infrared spectroscopy (FT-IR), proton and carbon-13 nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA). The compounds were screened for their antimicrobial properties against a list of Gram-positive bacterial strains.Results: The FT-IR spectra revealed that the Schiff bases acts as bidentate chelating ligand via nitrogen of the azomethine and phenolic oxygen atoms. NMR reveal the presence of azomethine (HC=N) and aromatic hydrogens at expected chemical shifts confirming the formation of the Schiff base ligands. Thermal decomposition behaviour was studied by thermogravimetry revealing stability up to 260 °C. The compounds were evaluated for their antibacterial potentials against Staphylococcus aureus and Enterococcus faecalis. The manganese acetylacetonato(N'-{(E)-[4-(diethylamino)-2-hydroxyphenyl]methylidene}-4-methoxybenzohydrazide: Mn(acac)(L2) exhibited antimicrobial activities against both Enterococcus faecalis and Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 398.0 μg/mL.Conclusion: The prepared compounds showed no inhibition against the selected pathogenic microorganisms except for Mn(acac)(L2) Standard antibacterial compounds: ampicillin and ciprofloxacin were used as positive control. The antibacterial activity of the compound depends on the kind of substituent on the benzo hydrazide rings at the para position, thereby suggesting the compound as promising chemotherapeutic agents for further structural optimization.

Lattice Matched Carbide–Phosphide Composites with Superior Electrocatalytic Activity and Stability

Composites of electrocatalytically active transition-metal compounds present an intriguing opportunity toward enhanced activity and stability. To identify potentially scalable pairs of a catalytically active family of compounds, we demonstrate that phosphides of iron, nickel, and cobalt can be deposited on molybdenum carbide to generate nanocrystalline heterostructures. Composites synthesized via solvothermal decomposition of metal acetylacetonate salts in the presence of highly dispersed carbide nanoparticles show hydrogen evolution activities comparable to those of state-of-the-art non-noble metal catalysts. Investigation of the spent catalyst using high resolution microscopy and elemental analysis reveals that formation of carbide–phosphide composite prevents catalyst dissolution in acid electrolyte. Lattice mismatch between the two constituent electrocatalysts can be used to rationally improve electrochemical stability. Among the composites of iron, nickel, and cobalt phosphide, iron phosphide display...

An Effective Lithium Sulfide Encapsulation Strategy for Stable Lithium–Sulfur Batteries

AbstractWith a high theoretical capacity of 1162 mA h g−1, Li2S is a promising cathode that can couple with silicon, tin, or graphite anodes for next‐generation energy storage devices. Unfortunately, Li2S is highly insulating, exhibits large charge overpotential, and suffers from active‐material loss as soluble polysulfides during battery cycling. To date, low‐cost, scalable synthesis of an electrochemically active Li2S cathode remains a challenge. This work demonstrates that the low conductivity and material loss issues associated with Li2S cathodes can be overcome by forming a stable, conductive encapsulation layer at the surface of the Li2S bulk particles through in situ surface reactions between Li2S and electrolyte additives containing transition‐metal salts. It is identified that the electronic band structure in the valence band region of the thus‐generated encapsulation layers, consisting largely of transition‐metal sulfides, determines the initial charging resistance of Li2S. Furthermore, among the transition metals tested, the encapsulation layer formed with an addition of 10 wt% manganese (II) acetylacetonate salt proved to be robust within the cycling window, which is attributed to the chemically generated MnS surface species. This work provides an effective strategy to use micrometer‐sized Li2S directly as a cathode material and opens up new prospects to tune the surface properties of electrode materials for energy‐storage applications.

Solid–state ion exchange of molybdenum (VI) acetylacetonate into ZSM-5 zeolite

The thermal decomposition of Mo(VI) acetylacetonate salt (Mo Acac) has been performed under helium stream between room temperature and 700°C (2Kmin−1) and monitored by thermogravimetric analysis coupled to mass spectrometry. The viscous MoO2(C5H7O2)2 salt evolves two acetylacetonato ligands between room temperature and 325°C which decompose into methane and acetic acid. Molybdenum dioxide MoO2(s) is the final product of decomposition as confirmed by the thermal behavior of pure MoO3(s) salt and thermodynamic calculations. In the presence of NH4+–ZSM-5 zeolite (6wt.% of Mo), the departure of the two ligands was accelerated and the salt transformed into MoO2(s) at 285°C. However, the oxidation of CH4 by molecular oxygen was inhibited at 245°C by the simultaneous formation of MoO3(s) and MoO2(OH)2(g). The solid–state exchange of the volatile MoO2(OH)2 specie and the protonated zeolite occurs between 320 and 570°C. Nevertheless, the exchange process overlaps with the partial dehydroxylation of the zeolite at 520°C.

Development of alternative environment friendly nickel and gold plating baths

In the metal plating industry, nickel and gold plating baths are used, which contain toxic materials and cause wastewater problems. Despite these disadvantages, there is a strong need for both these types of metal plating because of their aesthetic properties. However, until now, nickel plating has not been used in conjunction with gold plating because nickel plating baths contain sulphates. In this study, gold plating on a nickel plated surface is investigated using baths containing acetylacetonate salts. The physical parameters of the plated materials, which were favourable, were determined by hydrogen embrittlement tests, visible region spectrophotometry and the Charpy impact test.

Oxo‐vanadium(IV) Schiff base complex supported on modified MCM‐41: a reusable and efficient catalyst for the oxidation of sulfides and oxidative S–S coupling of thiols

Oxo‐vanadium(IV) Schiff base complex supported on MCM‐41 as an organic–inorganic hybrid heterogeneous catalyst was synthesized with post‐grafting of MCM‐41 with 3‐aminoropropyltrimethoxysilane and subsequent reaction with 3,4‐dihydroxybenzaldehyde and then complexation with oxo‐vanadium acetylacetonate salt. The catalyst was analysed using a series of characterization techniques such as Fourier transform infrared spectroscopy, small‐angle X‐ray diffraction, nitrogen absorption isotherm, transmission electron microscopy and thermogravimetric analysis. The data collected provided evidence that the vanadium complex was anchored onto MCM‐41. High catalytic activity of this catalyst was observed in the oxidation of various sulfides and thiols (into sulfoxides and disulfides, respectively) with urea hydrogen peroxide as oxidant in high to excellent yields and selectivity under mild conditions. The heterogeneous catalyst could be recovered easily and reused several times without significant loss in catalytic activity and selectivity. Copyright © 2015 John Wiley & Sons, Ltd.

Oxygen reduction reaction on palladium-modified zeolite 13X

Palladium was dispersed over zeolite NaX by procedure of impregnation/thermal degradation of palladium acetylacetonate salt. Samples characterization was performed by X-ray diffraction, SEM analysis, and chemical analysis. Palladium was present in modified zeolite as palladium oxide with content estimated to be about 8 wt.%. Electrochemical behavior of synthesized material was investigated in 0.1 M NaOH. The influence of addition of carbon black to composite electrode on its electrocatalytic performance was also investigated. The addition of carbon black altered the shape of voltammogram. The separated peak of reduction of α and β palladium oxides was visible only on voltammograms recorded without carbon black. Composite electrodes with and without carbon black were tested for oxygen reduction reaction. According to Koutecky–Levich slope, the oxygen reduction reaction followed 4e− mechanism on both electrodes. The onset of oxygen reduction reaction (ORR) on the electrode with added carbon black was shifted toward more positive potentials in comparison to the electrode without carbon black.

Size control synthesis and high coercivity L10-FePt nanoparticles produced by iron (III) acetylacetonate salt

Monodisperse 4.11nm FePt nanoparticles were synthesized via chemical co-reduction of iron (III) acetylacetonate and platinum (II) acetylacetonate by 1,2-hexadecanediol as a reducing agent. Then through the seed mediated growth process smaller sized FePt nanoparticles are used as seeds for the growth of larger sized particles. There is no specific limitation to achieve upper size range by this method. In this work, we have successfully synthesized FePt nanoparticles up to 8.32nm. After annealing these particles become ferromagnetic and their coercivirty increases with increasing particle sizes and reaches a maximum value of 17760Oe for size of 8.32nm.