Iron Acetylacetonate Research Articles

Influence of experimental parameters on iron oxide nanoparticle properties synthesized by thermal decomposition: size and nuclear magnetic resonance studies

A study of the experimental conditions to synthesize monodisperse iron oxide nanocrystals prepared from the thermal decomposition of iron(III) acetylacetonate was carried out in the presence of surfactants and a reducing agent. The influence of temperature, synthesis time and surfactant amounts on nanoparticle properties is reported. This investigation combines relaxometric characterization and size properties. The relaxometric behavior of the nanomaterials depends on the selected experimental parameters. The synthesis of iron oxide nanoparticles with a high relaxivity and a high saturation magnetization can be obtained with a short reaction time at high temperature. Moreover, the influence of surfactant concentrations determines the optimal value in order to produce iron oxide nanoparticles with a narrow size distribution. The optimized synthesis is rapid, robust and reproductive, and produces nearly monodisperse magnetic nanocrystals.

Cyclable membraneless redox flow batteries based on immiscible liquid electrolytes: Demonstration with all-iron redox chemistry

Membraneless redox flow batteries reported to date are microscale designs that have shown poor capacity retention and cyclability due to reactant crossover. Here, we present a new design of macroscale membraneless redox flow battery capable of recharging and recirculation of the same electrolyte streams for multiple cycles and maintains the advantages of the decoupled power and energy densities. The battery is based on immiscible aqueous anolyte and organic catholyte liquids, which exhibits high capacity retention and columbic efficiency during cycling. The aqueous anolyte consists of iron(II) sulfate (FeSO4) as active species, which is immiscible with the catholyte, having iron(III) acetylacetonate (Fe(acac)3) as active species dissolved in water-immiscible ethyl acetate, supported by ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide). Over 60% of initial discharge capacity was retained and over 80% of columbic efficiency was sustained after 25 cycles in a test flow cell, which is among the highest reported thus far.

Iron-Modified Mesoporous Silica as an Efficient Solid Lewis Acid Catalyst for the Mukaiyama Aldol Reaction

Fe-MCM-41 and Fe-SBA-15, two different iron-containing mesoporous silicas, were successfully synthesized by a straightforward and versatile method using iron acetylacetonate as a metal precursor. pH adjustment with ammonia during the synthesis was found to be an efficient way to improve the iron content. Physicochemical parameters of the iron-containing mesoporous silicas were obtained by nitrogen physisorption measurements, and the coordination environment of iron elements was validated by UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The surface acidity was tested by using a series of Hammett indicators. To further distinguish the Lewis acid sites on the surface, a pyridine adsorption FT-IR method was implemented. These prepared nanoporous catalysts were screened in the Mukaiyama aldol reaction as a model reaction catalyzed by a Lewis acid. The Lewis acid catalytic activity of the materials was fine-tuned, and the corresponding aldol products were obtained in good yield a...

Facile synthesis and excellent microwave absorption properties of FeCo-C core–shell nanoparticles

FeCo-C core–shell nanoparticles (NPs) with diameters of 10–50 nm have been fabricated on a large scale by one-step metal-organic chemical vapor deposition using the mixture of cobalt acetylacetonate and iron acetylacetonate as the precursor. The Fe/Co molar ratio of the alloy nanocores and graphitization degree of C shells, and thus the magnetic and electric properties of the core–shell NPs, can be tuned by the deposition temperature ranging from 700 °C to 900 °C. Comparative tests reveal that a relatively high Fe/Co molar ratio and low graphitization degree benefit the microwave absorption (MA) performance of the core–shell NPs. The composite with 20 wt% core–shell NP obtained at 800 °C and 80 wt% paraffin exhibits an optimal reflection loss of −60.4 dB at 7.5 GHz with a thickness of 3.3 mm, and an effective absorption bandwidth (frequency range for RL ≤10 dB) of 9.2 GHz (8.8–18.0 GHz) under an absorber thickness of 2.5 mm. Our study provides a facile route for the fabrication of alloy-C core–shell nanostructures with high MA performance.

The theoretical chemical calculations clarify the mechanism of beta-alkylation of 1-phenylethanol with benzyl alcohol catalyzed by iron(ii) acetylacetonate methods.

Iron(ii) acetylacetonate was suggested to be a better catalyst of the β-alkylation of 1-phenylethanol with benzyl alcohol to form 1,3-diphenyl-1-propanol. DFT calculations have been performed to study the internal mechanism, the structures of intermediates and transition states, and the exchange of electronic density in detail. The energetic results show that this β-alkylation reaction proceeds via the hydrogen autotransfer mechanism and the catalytic cycle includes three sequential stages: (1) alcohol oxidation to produce aldehyde associated with hydride anion transfer, (2) cross-aldol condensation to form a chalcone and (3) chalcone reduction with multi-step hydrogenation. In order to study whether the only by-product, water, has clearly influenced the reaction, eight catalyst hydrogenation pathways and four catalyst dehydrogenation pathways have been studied. We are delighted to find that the presence of the only by-product, water, can significantly increase the reduction energy barrier of dihydrochalcone. The energy barrier of the catalyst's hydrogenation is less than 6 kcal mol−1. Our calculation results are fundamentally coincident with the experimental detections, and suggest that the crossing-coupling reaction occurs through a reliable mechanism. Two dihydrochalcone catalysts were designed on the basis of how the β-alkylation reaction proceeds.

Flexible Fe3Si/SiC ultrathin hybrid fiber mats with designable microwave absorption performance.

Flexible Fe3Si/SiC ultrathin fiber mats have been fabricated by electrospinning and high temperature treatment (1400 °C) using polycarbosilane (PCS) and ferric acetylacetonate (Fe(acac)3) as precursors. The crystallization degree, flexibility, electrical conductivity, dielectric loss and microwave absorption properties of the hybrid fibers have been dramatically enhanced by the introduction of Fe. Fe3Si nanoparticles with a diameter around 500 nm are embedded in SiC fibers. As the Fe3Si content increases from 0 to 6.5 wt%, the related saturation magnetization (Ms) values increase from 0 to 8.4 emu g−1, and the electrical conductivity rises from 7.9 × 10−8 to 3.1 × 10−3 S cm−1. Moreover, the flexibility of Fe3Si/SiC hybrid fiber mats is greatly improved and remains intact after 500 times 180°-bending testing. Compared with pure SiC fibers, the Fe3Si/SiC hybrid fibers process higher dielectric and magnetic loss, which would be further advanced as more Fe3Si phase is introduced. At the optimal Fe3Si content of 3.8 wt%, the Fe3Si/SiC fibers/silicon resin composite (5 wt%) exhibits minimal reflection loss (RL) of −22.5 dB at 16.5 GHz and 2.5 mm thickness with a wide effective absorption bandwidth (EAB, RL < −10 dB) of 8.5 GHz. The microwave absorption performance can be further promoted by multi component stacking fiber mat composites which contain both low and high Fe3Si content layers. Furthermore, the position of the microwave absorption bands can also be simply manipulated by designing the stacking components and structure.

3D Porous Carbon Framework Stabilized Ultra-Uniform Nano γ-Fe2 O3 : A Useful Catalyst System.

We present a novel strategy for the scalable fabrication of γ-Fe2 O3 @3DPCF, a three-dimensional porous carbon framework (PCF) anchored ultra-uniform and ultra-stable γ-Fe2 O3 nanocatalyst. The γ-Fe2 O3 @3DPCF nanocomposites were facilely prepared with the following route: condensation of iron(III) acetylacetonate with acetylacetonate at room temperature to form the polymer precursor (PPr), which was carbonized subsequently at 800 °C. The homogeneous aldol condensation offered an ultra-uniform distribution of iron, so that the γ-Fe2 O3 nanoparticles (NPs) were uniformly distributed in the 3D carbon architecture with the average size of approximate 20 nm. The Fe2 O3 NPs were capped with carbon, so that the iron oxide maintained its γ-phase instead of the more stable α-phase. The nanocomposite was an excellent catalyst for the reduction of nitroarene; it gave >99 % conversion and 100 % selectivity for the reduction of nitroarenes to the corresponding anilines at 100 °C. The fabrication of the γ-Fe2 O3 @3DPCF nanocatalyst represents a green and scalable method for the synthesis of novel carbon-based metal oxide nanostructures.

Carbon Nanofibers Loaded with Carbon Nanotubes and Iron Oxide as Flexible Freestanding Lithium-Ion Battery Anodes

We demonstrate the fabrication of flexible electrospun carbon nanofibers (CNFs) containing uniformly distributed carbon nanotubes (CNTs) and iron oxide (FeOx) nanoparticles (NPs) as a composite material for lithium-ion battery (LIB) anodes. The uniform incorporation of CNTs and FeOx NPs within the CNFs was confirmed by transmission electron microscopy. Embedding even a small amount of CNTs (0.1wt%) in the CNFs increased the LIB performance by a factor of two compared with pure CNFs. The specific capacity was also increased, by 25%, when an iron source (iron (III) acetylacetonate) was added at a concentration of 2wt%. The FeOx-CNT/CNF electrode maintained a capacity of 1008 mAh∙g−1 at a current density of 100 mA∙g−1 after 100 cycles. Further, the high-performance anode material was freestanding, flexible, and lightweight. This makes it suitable for next-generation LIBs, which must deliver high power over long periods while also being light and flexible.

Sol–gel synthesis of iron yttrium garnet Y3Fe5O12 using metal acetylacetonates

The synthesis of hydrolytically active heteroligand complexes of the composition [M(O2C5H7)x(iOC5H11)y] (M = Fe3+ and Y3+) using iron and yttrium acetylacetonates was studied. Their reactivity was shown to be dependent on the degree of shielding of iron and yttrium cations in hydrolysis and polycondensation during the formation of a connected dispersion system. The crystallization temperature of iron yttrium garnet Y3Fe5O12 upon heating xerogel was determined. It was found that the dispersity, microstructure, and magnetic characteristics of the products depend on the synthesis conditions.

Lignin conversion to hydrogen-containing gas under the action of microwave radiation

The paper describes the carbon dioxide reforming of lignin in the presence of Ni-, Fe, and Ni/Fe-containing active components formed directly on the surface under microwave irradiation. The deposition of 0.1 wt % iron acetylacetonate on the lignin surface results in a sharp increase in the microwave absorption capacity at a 0.5 kW power and induces lignin conversion to hydrogen-containing gas with a degree of hydrogen recovery reaching 90 %. The maximum lignin conversion (65%) is attained in 10 min under microwave irradiation. It was shown for the first time that deposition of metals (Fe and Ni) on lignin can provide for targeted change of the selectivity of reforming to synthesis gas and the process can thus be classified as a plasma catalytic one. Using the obtained results, it is possible to minimize the amount of catalyst and to propose an efficient route for hydrogen and synthesis gas production from lignin waste.

Carbon nanofibers decorated with FeOx nanoparticles as a flexible electrode material for symmetric supercapacitors

We have produced flexible, freestanding, and light weight mats of FeOx-decorated carbon nanofibers (CNFs) and demonstrated their use in supercapacitors with high energy and power density and excellent long term capacitance retention. Highly flexible carbon-iron oxide nanofibers were synthesized by electrospinning a solution of polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), and iron acetylacetonate (FeAcAc), followed by annealing to carbonize the PAN, pyrolyze the PMMA to produce pores, and convert FeAcAc to FeO nanoparticles. The morphology of the FeOx/CNF composite was determined by scanning and transmission electron microscopies, which showed that the embedded FeOx nanoparticles were well distributed in the CNF electrode. We employed cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy to evaluate the electrochemical performance of symmetric supercapacitors prepared from the FeOx/CNF composite. The supercapacitors exhibited high specific capacitance (427F·g−1 at 10mV·s−1 and 436F·g−1 at 1A·g−1 in the optimal case) and good stability, retaining 89% of their initial capacitance after 5000 cycles at a current density of 1A·g−1. The optimal device achieved an energy density of 167Wh·kg−1 at a power density of 0.75kW·kg−1, and an energy density of 66Wh·kg−1 at a power density of 7.5kW·kg−1. These combinations of energy and power densities can meet the needs of many emerging supercapacitor applications.

Development of Fe2O3-based, Al2O3-stabilized Oxygen Carriers using Sol-gel Technique for H2 Production via Chemical Looping

A modification of the chemical looping combustion (CLC) process allows the production of high purity hydrogen from biomass (with simultaneous CO2 capture) on the distributed scale. Here, we report the development of Fe2O3-based, Al2O3-supported oxygen carriers using a sol-gel technique. We assess the influence of the iron precursor on the morphological properties, chemical composition and cyclic redox stability of the oxygen carrier. Three iron precursors, i.e. iron nitrate, iron chloride and iron acetylacetonate, were used to synthesize oxygen carriers containing 80wt. % of Fe2O3. Using iron nitrate and iron acetylacetonate as the iron precursor resulted in materials with a high H2 yield. However, both materials showed some decay in the hydrogen yield with cycle number. Al2O3-stabilized Fe2O3 synthesized using iron chloride as the iron precursor showed no appreciable decay over the 15 cycles tested, albeit the amount of hydrogen produced was significantly lower when compared to the other two iron precursors. This observation can be attributed to the large fraction of hercynite (FeAl2O4) in this material. Hercynite stabilizes iron and prevents sintering, but does not participate in the redox reactions.

Microwave absorption properties of SiC@SiO2@Fe3O4 hybrids in the 2\u201318 GHz range

To enhance the microwave absorption performance of silicon carbide nanowires (SiCNWs), SiO2 nanoshells with a thickness of approximately 2 nm and Fe3O4 nanoparticles were grown on the surface of SiCNWs to form SiC@SiO2@Fe3O4 hybrids. The microwave absorption performance of the SiC@SiO2@Fe3O4 hybrids with different thicknesses was investigated in the frequency range from 2 to 18 GHz using a free-space antenna-based system. The results indicate that SiC@SiO2@Fe3O4 hybrids exhibit improved microwave absorption. In particular, in the case of an SiC@SiO2 to iron(III) acetylacetonate mass ratio of 1:3, the microwave absorption with an absorber of 2-mm thickness exhibited a minimum reflection loss of −39.58 dB at 12.24 GHz. With respect to the enhanced microwave absorption mechanism, the Fe3O4 nanoparticles coated on SiC@SiO2 nanowires are proposed to balance the permeability and permittivity of the materials, contributing to the microwave attenuation.

One-Step Facile Synthesis of Highly Magnetic and Surface Functionalized Iron Oxide Nanorods for Biomarker-Targeted Applications.

We report a one-step method for facile and sustainable synthesis of magnetic iron oxide nanorods (or IONRs) with mean lengths ranging from 25 to 50 nm and mean diameters ranging from 5 to 8 nm. The prepared IONRs are highly stable in aqueous media and can be surface functionalized for biomarker-targeted applications. This synthetic strategy involves the reaction of iron(III) acetylacetonate with polyethyleneimine in the presence of oleylamine and phenyl ether, followed by thermal decomposition. Importantly, the length and diameter as well as the aspect ratio of the prepared IONRs can be controlled by modulating the reaction parameters. We show that the resultant IONRs exhibit stronger magnetic properties compared to those of the widely used spherical iron oxide nanoparticles (IONPs) at the same iron content. The increased magnetic properties are dependent on the aspect ratio, with the magnetic saturation gradually increasing from 10 to 75 emu g-1 when increasing length of the IONRs, 5 nm in diameter, from 25 to 50 nm. The magnetic resonance imaging (MRI) contrast-enhancing effect, as measured in terms of the transverse relaxivity, r2, increased from 670.6 to 905.5 mM-1 s-1, when increasing the length from 25 to 50 nm. When applied to the immunomagnetic cell separation of the transferrin receptor (TfR)-overexpressed medulloblastoma cells using transferrin (Tf) as the targeting ligand, Tf-conjugated IONRs can capture 92 ± 3% of the targeted cells under a given condition (2.0 × 104 cells/mL, 0.2 mg Fe/mL concentration of magnetic materials, and 2.5 min of incubation time) compared to only 37 ± 2% when using the spherical IONPs, and 14 ± 2% when using commercially available magnetic beads, significantly improving the efficiency of separating the targeted cells.

Colloidal Flower‐Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings

The assembly of magnetic cores into regular structures may notably influence the properties displayed by a magnetic colloid. Here, key synthesis parameters driving the self‐assembly process capable of organizing colloidal magnetic cores into highly regular and reproducible multi‐core nanoparticles are determined. In addition, a self‐consistent picture that explains the collective magnetic properties exhibited by these complex assemblies is achieved through structural, colloidal, and magnetic means. For this purpose, different strategies to obtain flower‐shaped iron oxide assemblies in the size range 25–100 nm are examined. The routes are based on the partial oxidation of Fe(OH)2, polyol‐mediated synthesis or the reduction of iron acetylacetonate. The nanoparticles are functionalized either with dextran, citric acid, or alternatively embedded in polystyrene and their long‐term stability is assessed. The core size is measured, calculated, and modeled using both structural and magnetic means, while the Debye model and multi‐core extended model are used to study interparticle interactions. This is the first step toward standardized protocols of synthesis and characterization of flower‐shaped nanoparticles.

Facile large scale fabrication of magnetic carbon nano-onions for efficient removal of bisphenol A

In this work, a scalable and cost-effective approach was developed for the synthesis of magnetic carbon nano-onions (MCNOs) by using iron (III) acetylacetonate modified candle as the raw materials. The candle soot was collected from the burning candle and then subjected to calcination at 800 °C under N2 atmosphere. The obtained MCNOs were further applied as adsorbent for the removal of bisphenol A (BPA) from aqueous solutions. Adsorption of BPA onto the MCNOs was investigated with the influence of initial concentration of BPA, solution pH, and adsorption time. The results demonstrated the adsorption of BPA onto the MCNOs was almost not affected by pH in the range from 5–9. The adsorption isothermal and kinetic's data were better fitted by Langmuir isotherm and pseudo-second-order kinetic model, respectively. Moreover, the MCNOs are easily recycled by using and external magnet and regenerated by simply methanol washing. The results present here not only provide a novel synthetic approach toward low-cost nanocarbons but also revealed the great application potential of the MCNOs for the removal of endocrine disrupting compounds from aqueous solution.

Preparation of Iron Oxide Particle-Decorated Lignin-Based Carbon Nanofibers as Electrode Material for Pseudocapacitor

Iron oxide particle-decorated lignin-based carbon nanofibers (IO-LCNFs) were fabricated from organic mixtures containing acetic acid lignin (AAL) together with ferric acetylacetonate (Fe(acac)3) via electrospinning followed by stabilization in air and carbonization in nitrogen. After the addition of Fe(acac)3, IO-LCNFs showed different morphologies: Non-fused IO-LCNFs were obtained with diameters of 400–500 nm; iron oxide nanoparticles with diameters of 30–60 nm were exposed outside and well-distributed when sufficient amounts of Fe(acac)3 were added. These carbon nanofibers were then used as electrode material for pseudocapacitor. It was found that the iron oxide particles enhanced the resulting electrochemical properties via reversible redox reactions. IO-LCNFs made from the composite nanofibers with mass ratio of AAL/Fe(acac)3 of 80/20 [i.e., IO-LCNFs (80/20)] exhibited the highest specific capacitance, 72.1 F g−1, at current density of 500 mA g−1.

Seeded Growth Synthesis of Au–Fe3O4 Heterostructured Nanocrystals: Rational Design and Mechanistic Insights

Multifunctional hybrid nanoparticles comprising two or more entities with different functional properties are gaining ample significance in industry and research. Due to its combination of properties, a particularly appealing example is Au–Fe3O4 composite nanoparticles. Here we present an in-depth study of the synthesis of Au–Fe3O4 heterostructured nanocrystals (HNCs) by thermal decomposition of iron precursors in the presence of preformed 10 nm Au seeds. The role of diverse reaction parameters on the HNCs formation was investigated using two different precursors: iron pentacarbonyl (Fe(CO)5) and iron acetylacetonate (Fe(acac)3). The reaction conditions promoting the heterogeneous nucleation of Fe3O4 onto Au seeds were found to significantly differ depending on the precursor chosen, where Fe(acac)3 is considerably more sensitive to the variation of the parameters than Fe(CO)5 and more subject to homogeneous nucleation processes with the consequent formation of isolated iron oxide nanocrystals (NCs). The r...

Polyol Synthesis of Magnetite Nanocrystals in a Thermostable Ionic Liquid

We report on the development of a facile, one-pot synthesis of single-crystalline magnetite (Fe3O4) nanoparticles (NPs) based on the thermal decomposition of the nontoxic iron precursor iron(III)acetylacetonate within the ionic liquid trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P6,6,6,14][Tf2N]) using 1,2-hexadecanediol as a polyol reducing agent in an “iono-polyol” process. In this expedient approach, the [P6,6,6,14][Tf2N] acts both as a low-volatility, thermostable solvent and as the colloid-stabilizing agent, eliminating the requirement for additional surface-capping agents. Performing the synthesis at 300 or 350 °C yielded quasi-spherical, monodispersed Fe3O4 NPs with a mean size of 14 nm. Evidence from thermogravimetry, X-ray fluorescence, and infrared analysis is consistent with nanocrystal coverage by a partial bilayer of [P6,6,6,14][Tf2N], accounting for the excellent dispersibility of the Fe3O4 NPs in solvents such as hexane, toluene, and methylene chloride. Time-dependent t...

One-pot synthesis of a C/SiFeN(O)-based ceramic paper with in-situ generated hierarchical micro/nano-morphology

In the present study, a C/SiFeN(O)-based ceramic paper with in situ generated hierarchical micro/nano-morphology was prepared upon thermal treatment of a cellulose-base paper surface-modified with a polymeric single-source precursor prepared from perhydropolysilazane (PHPS) and iron(II) acetylacetonate (Fe(acac)2). The ammonolysis at 1000°C of the paper/precursor hybrid materials leads to a C/SiFeN(O)-based ceramic paper which exhibits the same morphology as that of the cellulose paper. Subsequent annealing of the ceramic paper in nitrogen atmosphere at temperatures from 1200 to 1400°C results in the in-situ generation of ultra-long silicon nitride nanowires with aspect ratios in the range of 103 on the surface and in the macropores of the ceramic paper. The nanowires exhibit round Fe3Si tips at the end, indicating that the growth occurred via iron-catalyzed VLS (vapor-liquid-solid) mechanism. The combination of single-source precursor, porous template and in situ VLS growth of 1D nanostructures provides a convenient one-pot synthesis approach to produce ceramic nanocomposites with hierarchical morphologies.