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•Acetylene hydrogenation over FexOy clusters are theoretically investigated.•Acetylene hydrogenation over 5FeO cluster is impossible for the high energy barrier.•Acetylene ...hydrogenation to ethane over Fe2O3 cluster is kinetically most favorable.
The acetylene hydrogenation reaction over FeO, Fe2O3 and Fe3O4 clusters are theoretically investigated, via C2H2 adsorption, approach of molecular H2 to cluster, H2 dissociation on FeO bond, and the sequential addition reaction of H atom. Over FeO cluster, the extremely high barrier for the addition reaction of H atom adsorbed on O atom (of cluster) predicts the impossible acetylene hydrogenation. Over Fe2O3 cluster, the overall barriers for H2 dissociation, addition reaction of two hydrogen atom are respectively 26.6, 32 and 31.8 kcal·mol−1 during the acetylene hydrogenation to form ethylene and 26.5, 35.5 and 9.1 kcal·mol−1 for its further hydrogenation to produce ethane. During the further hydrogenation pathway, the migration of semi-hydrogenated product C2H3 requires extra energy of 30.7 kcal mol−1. These barriers are lower than those of the pathways over Fe3O4 cluster. Hence, among three FexOy clusters, hydrogenation of acetylene to produce ethane on Fe2O3 cluster is kinetically most favorable.
In this study, natural mackinawite (FeS), a chalcophilic mineral, was utilized to prepare iron/copper bimetallic oxides (CuO@FexOy) by displacement plating and calcination process. Various ...characterization methods prove that Cu0 is successfully coated on the surface of FeS, which were further oxidized to CuO, Fe3O4 and/or Fe2O3 during calcination process, respectively. CuO@FexOy performed highly efficient capacity to activate PMS for the degradation of various emerging pollutants including sulfamethoxazole (SMX), carbamazepine (CBZ), bisphenol A (BPA), 2,4-dichlorophenol (2,4-DCP) and diclofenac (DCF) in aqueous solution. Complete removal of the above pollutants was observed after 8 min of CuO@FexOy/PMS treatment. Taking SMX as an example, the key parameters including CuO@FexOy dosage, PMS dosage and initial pH were optimized. The results show that the catalytic system can be worked in a wide pH range (3.0-9.0). The quenching experiments and electron spin resonance (ESR) test demonstrated that the main reactive oxygen species in CuO@FexOy/PMS system were hydroxyl radicals (•OH) and sulfate radicals (SO4•¯), and SO4•¯ was the primary reactive species. Besides, the influence of coexisting anions (i.e., Cl¯, NO3¯, HCO3¯ and H2PO4¯) for the degradation of SMX was explored. CuO@FexOy/PMS system can maintain good catalytic activity and reusability in different water bodies and long-term running. This work provided a green strategy to fabricate the efficient catalyst in PMS-based advanced oxidation processes.
The CuO@FexOy particles were prepared by displacement plating with Cu2+ and calcination process in air atmosphere. Free radicals including hydroxyl radicals (•OH) and sulfate radicals (SO4•–) were the main reactive oxygen species (ROS) for the degradation of sulfamethoxazole. Display omitted
FexOy-type iron oxides, especially α-Fe2O3 and Fe3O4, are powerful alternatives to the currently available graphitic anode materials for lithium-ion batteries (LIBs) owing to their high theoretical ...capacity, natural abundance, environmental benignity, non-flammability, and enhanced safety. In this context, compositional engineering is a widely used strategy to improve the electrochemical performance of electrode materials; in this method, the synergetic effects of individual components in a hybrid material are harnessed for improved performance. To improve FexOy-based materials in terms of compositional engineering, in this review, the factors affecting the electrochemical performance of pure FexOy and different kinds of additives combined with FexOy for LIB anodes via doping or compositing and their effects on the electrochemical performance of the anodes are discussed in detail. Several approaches that can enhance the performance of FexOy-based LIB anodes via compositional engineering are highlighted and the importance of a proper combination of compositional and structural engineering for achieving the desired physical/electrochemical properties in FexOy-type anodes is described. In the near future, such approaches may provide effective and efficient ways to obtain advanced rechargeable LIBs with a high energy/power density, long cycle life, and low cost.
•A review on FexOy for advanced LIBs in compositional engineering is reported.•Almost all kinds of materials combined with FexOy for LIBs since 1991 are discussed.•The electrochemical effects of each kind material combined with FexOy are summarized.•Doping and compositing effects are separately discussed.
The saucer-shaped CNF/FexOy wafers were synthesized by a sol–gel and annealing route, exhibiting a high thermal conductivity, wide absorption band, prominent EMI shielding effectiveness and excellent ...electrical insulation.
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•A sol–gel and annealing strategy for saucer-shaped CNF/FexOy wafers.•Precisely regulating the texture, composition and defects of CNF/FexOy wafers.•Optimizing the thermal conductivity and EMW absorbing/shielding properties.•Revealing the synergistic enhancement mechanism.
The property incompatibility among heat conduction, electromagnetic wave (EMW) absorption/shielding, and electrical insulation has restricted the synchronous enhancement and application of polymer-based composites. Herein, we first synthesized porous 3D interlinked C nanofiber/FexOy (CNF/FexOy) wafers for significantly enhanced properties by a simple sol–gel and annealing route. The texture, composition, defects and the resulting properties can conveniently be manipulated via altering Fe3+ concentration and annealing temperature. The CNF/FexOy wafers exhibit a high heat conductivity (3.22 W/mK) at a low loading (30 wt%) thanks to the shorter continuous thermal transfer paths and the increased phonon mean free path and thermal capacity of phonons per volume. Moreover, CNF/FexOy wafers possess a wide absorption band (9.36 GHz), prominent EMI shielding effectiveness (SET ≥ 20 dB over C, X, and Ku bands), excellent electrical insulation (σ = 0.00991 S/m), and enhanced mechanical/hydrophobicity properties, surpassing most reported fillers. These enhancements could be explained by the fact that the cooperative action of porous structures, defects, and magnetic/dielectric FexOy hinder electron migration and improve the impedance matching and multiple-scattering of materials. The silicone composites supported by 3D interlinked CNF/FexOy wafers have great potential as a filler with high-performance EMI shielding/absorption and thermal control in next-generation flexible electronics.
Activated carbon supported iron-based catalysts (FexOy/AC) show good deNOx efficiency at low temperature. The doping of chromium (Cr) greatly improves the catalyst activity. However, the detailed ...effect of doping Cr over FexOy/AC surface at molecular level is still a grey area. In this study, the roles of Cr dopant on gas adsorption and NO oxidation were deeply investigated by a DFT-D3 method. Results show that the synergy of Cr–Fe bimetal improves the binding capacity of Fe2O3/AC and Fe3O4/AC surfaces after doping Cr. NH3 can be adsorbed on Cr and Fe sites to form coordinated NH3. Doping Cr greatly improves the NH3 adsorption property on the Fe3O4/AC surface. NO molecule can combine with Cr, Fe, and O sites to form nitrosyl and nitrite. The doping of Cr increases the adsorption performance of NO on the Fe2O3/AC and Fe3O4/AC surfaces, especially for Fe3O4/AC surface. Furthermore, NO can be oxidized to NO2 by adsorption oxygen or active O sites of FexOy clusters. The doping of Cr restrains the formation of insoluble chelating bidentate nitrates and greatly reduces the reaction energy barrier of NO oxidation on the FexOy/AC surface, which can promote the deNOx reaction.
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•Doping Cr enhances the binding property of Fe2O3/AC and Fe3O4/AC system.•Doping Cr greatly improves NH3 and NO adsorption property on the Fe3O4/AC surface.•NO can be oxidized to NO2 based on adsorbed oxygen.•Doping Cr greatly reduces the energy barrier of NO oxidation.•Doping Cr restrains the formation of insoluble chelating bidentate nitrate.
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•A set of MFI samples with framework Fe3+ and Al3+ ions were prepared and characterized.•Magnetic susceptibility is very effective to characterize FexOy nanoparticles.•Small-sized ...FexOy nanoparticles are the most active species for N2O decomposition.•In high Fe loading preparations, the number of small-sized FexOy nanoparticles increases.•Framework Al3+ ions enhance the catalytic activity of small-sized FexOy nanoparticles.
In this work, some Fe-MFI catalysts at different Fe loadings and Si/Al ratios have been prepared by loading only Fe3+ ions, in the case of Fe-S-1 specimens, or Fe3+ and Al3+ ions, in the case of Fe-ZSM-5 preparations, into the synthesis solutions prior to crystallization in order to have in both sets of materials the Fe3+ ions occupying the MFI zeolite framework sites. These catalysts have been characterized in either the as synthesized state or after thermal treatment in air at high temperature with different methods as porosimetry, UV–Vis diffuse reflectance spectroscopy (DRS), Gouy balance for magnetic susceptibility measurements. Moreover, an assay of 57Fe Mössbauer spectroscopy was also made on a few representative samples. The combined investigation with the above spectroscopic and magnetic techniques was useful to clarify the iron chemical state, and the nature of the FexOy nanoparticles formed upon dehydration at high temperature in the calcined samples. Our findings suggest that most of the FexOy nanoparticles are formed inside the MFI structure by gradual migration of Fe3+ ions from framework sites in consequence of the calcination in air at 823K. These FexOy nanoparticles can have different nuclearity regardless the iron loading but, interestingly, likely due to the gradual migration, it seems that FexOy nanoparticles with lower nuclearity are formed even in the material with the highest iron loading and that they are located inside the interconnected channel systems of the MFI framework. The catalytic behavior for the N2O decomposition of the Fe-S-1 and Fe-ZSM-5 catalysts was also investigated. It was found that the catalytic activity is depending on the nuclearity of the FexOy nanoparticles formed inside the MFI structure and it is suggested the FexOy nanoparticles with lower nuclearity located inside the channel systems of the MFI framework are responsible for the catalytic activity. Finally, on the basis of a comparison between the catalysts with and without aluminum, that is, the Fe-ZSM-5 and Fe-S-1 materials, respectively, it was further confirmed that the framework aluminum has a beneficial effect on the N2O decomposition catalytic activity.
Detection of cardiac troponin I (cTnI) plays a critical role in diagnosing acute myocardial infarction (AMI). In this report, a new kind of spherical AuPt@FexOy core@shell nanoparticles (termed as ...AuPt@FexOy NPs) were one-pot synthesized by a redox interaction-engaged strategy (RIES) without the addition of any surfactants or reducing agents. The as-synthesized AuPt@FexOy NPs not only retain the plasmonic activity of gold nanoparticles (AuNPs), but also possess excellent catalytic activities of platinum nanoparticles (PtNPs) and FexOy nanoclusters. The features of AuPt@FexOy NPs enable greatly enhance the colorimetric detection sensitivity of lateral flow immunoassay (LFIA) through integrating AuPt@FexOy NPs labeling procedure and catalyzing oxidation of chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) signal amplification strategy. The as-developed colorimetric LFIA (termed as AuPt@FexOy-LFIA) exhibits the limit of detection (LOD) as 26.0 pg mL−1 cTnI under the TMB signal amplification mode. In particular, the detection results of cTnI in 40 clinical seral samples by AuPt@FexOy-LFIA are correlated well with those of cTnI in the same samples by commercial enzyme-linked immunosorbent assay (ELISA) detection kit (R2 = 0.97, slope = 1), demonstrating the highly reliable analytical performance and good application prospect of AuPt@FexOy-LFIA.
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•A simple scalable method was developed to prepare SnOx/FexOy/C.•The performance of SnOx/FexOy/C as a lithium-ion battery anode was demonstrated.•The multi-component structure offered ...SnOx/FexOy/C enhanced kinetics and structural stability.•The SnOx/FexOy/C showed good lithium storage performance.
For a promisng anode material, a simple scalable preparation route is as important as its performance. Therefore, it is of great significance to develop a simple scalable preparation route for anode materials. Herein, a very simple scalable route is demonstrated to fabricate SnOx/FexOy/C composite composed of SnOx/FexOy hybrid nanoparticles embedded within an in-situ formed porous carbon matrix. Moreover, this composite has enhanced durability and kinetics during electrochemical cycling process and hence shows good performance with 628 mAh g−1 after 100 cycles at 200 mA g−1. This work may spark some inspirations to fabricate other polymetallic oxides for advanced LIB anodes.
Reasonable microstructure design and composition of absorbing materials are essential to improve absorbing properties. In this paper, ZSM-5/FexOy@C/Ni composite absorbing material with double ...core-shell structure was prepared by hydrothermal method and sol-gel method. The composite's structure, morphology, chemical composition, and magnetic properties were studied. The surface and C layer of ZSM-5 were densely covered with FexOy and Ni nanoparticles, respectively. At the same time, the uniform distribution of magnetic units can effectively improve the spatial distribution of magnetism. It was worth noting that the optimized composites had excellent microwave absorption properties. When the sample thickness was 2.5 mm, the minimum reflection loss of the sample could reach −21.4 dB, and the maximum effective bandwidth could reach 5.4 GHz. It was found that by changing the carbon layer's thickness, the prepared sample's absorption property could be adjusted to achieve the best impedance matching. The superior electromagnetic absorption performance of ZSM-5/FexOy@C/Ni composite microspheres was due to the synergistic effect of dielectric loss and magnetic loss and the enhanced porous core-shell interface effect. These results indicated that the composite could be used as a promising new type of high-performance absorbing material.
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![N2O decomposition over [Fe]...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0021-9517/small "N2O decomposition over [Fe]-MFI catalysts: Influence of the FexOy nuclearity and the presence of framework aluminum on the catalytic activity")
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