Fe Nanocomposites Research Articles

Nature-mimic fabricated polydopamine/MIL-53(Fe): efficient visible-light responsive photocatalysts for the selective oxidation of alcohols

PDA/MIL-53(Fe) nanocomposites prepared via a nature-mimicking method were efficient catalysts towards the photocatalytic selective oxidation of alcohols to aldehydes or ketones by a direct holeoxidation process under visible-light illuminated conditions.

A “bottle-around-ship” like method synthesized yolk-shell Ag3PO4@MIL-53(Fe) Z-scheme photocatalysts for enhanced tetracycline removal

A novel yolk-shell Ag3PO4@MIL-53(Fe) Z-scheme photocatalyst was fabricated via a “bottle-around-ship” like method. Experiments on the treatment of tetracycline upon visible light irradiation showed that the as-prepared photocatalyst possessed excellent photocatalytic performance. Experimental results showed that tetracycline removal efficiency of the yolk-shell Ag3PO4@MIL-53(Fe) Z-scheme photocatalyst was almost 3 times higher than that of MIL-53(Fe). The enhanced photocatalytic performance of Ag3PO4@MIL-53(Fe) nanocomposite could be contributed to its higher surface area, better absorption capability, and greater charge separation efficiency. In addition, the H2O2 concentration detection results for Ag3PO4 (154 μmol/L) and Ag3PO4@MIL-53(Fe) (52 μmol/L) indicated that a big part of generated H2O2 on the Ag3PO4 core would be quickly decomposed by the MIL-53(Fe) shell and generated more reactive species through the photo-Fenton-like reaction, which is beneficial for the improvement of photocatalytic performance. This is a promising approach to fabricate yolk-shell structure photocatalyst and a different aspect to design multiple semiconductor composites heterojunction for environmental remediation.

Physicochemical behavior of M doped Zn0.95Cu0.05O nanocomposites synthesized by facile sol–gel method

In the present work, the synthesis of Zn0.94Cu0.05M0.01O (M=Ag; Ni; Fe) nanocomposites by a simple sol-gel method is illustrated. XRD, SEM, EDX and FTIR were utilized to characterize the prepared nanocomposites structure; additionally, their porosity and surface area were investigated via N2 adsorption. The XRD data asserted the pertinence of the ZnO hexagonal wurtzite structure with the evolution of a CuO monoclinic phase. The FTIR analysis emphasized the bonding of the metal ions to the ZnO host as dictated by a shift in the Zn–O vibration mode. The dielectric properties variations with frequencies as a consequence of the incorporation of M-ions in the Zn0.95Cu0.05O nanocomposite showed that the dielectric constant, dielectric loss tangent and conductivity values were found to change inversely with the applied frequencies. On the other hand a direct dependence of impedance was observed. Hopping of charge carriers between ions such as Fe2+ → Fe3+ and Cu2+ + M+n → Cu+ + M+n+1 may be the cause for the electrical and dielectric dispersion in the samples. The above mentioned findings make these materials promising candidates for optoelectronic and photocatalytic applications.

Enhanced hydrogenation and hydrolysis properties of core-shell structured Mg-MOx (M = Al, Ti and Fe) nanocomposites prepared by arc plasma method

In this work, three amphoteric metal oxides (Al2O3, TiO2 and Fe2O3) are introduced into Mg ultrafine powders via arc plasma method in order to improve hydrogen absorption properties of Mg and hydrolysis performances of MgH2. The phase components, particle size distribution, microstructures and compositions of pure Mg and core-shell structured Mg-MOx nanocomposites at various states are carefully characterized. Among all composites, the addition of TiO2 followed by passivation shows the best promotion effects on hydrogen absorption and hydrolysis performances. The passivated Mg-TiO2 composite absorbs 5.5 wt% of H2 in less than 5 min at 623 K and the hydrogenated composite produces more than 1000 mL g−1 H2 in 660 s (maximum 1525 mL g−1 for 1 h) in 0.1 M MgCl2 water solution at 298 K. The activation energy of hydrolysis decreases from 53.42 kJ mol−1 H2 for hydrogenated pure Mg powder (passivated) to 45.14 kJ mol−1 H2 for the hydrogenated Mg-TiO2 powder (passivated). Corresponding analyses reveal that TiO2 formed on the surface of Mg particles, together with the defects in Mg lattice accounts for the improved hydrogen absorption properties, the enhanced hydrolysis rate and yield of the hydrogenated Mg-TiO2 powder.

磁性壳聚糖/ZnS∶Fe复合纳米粒子的制备及其对孔雀石绿的光催化降解

磁性壳聚糖/ZnS∶Fe复合纳米粒子的制备及其对孔雀石绿的光催化降解

Enhanced Electrochemiluminescence Detection for Hydrogen Peroxide Using Peroxidase-Mimetic Fe/N-Doped Porous Carbon

Detecting hydrogen peroxide (H2O2) is obviously indispensable on account of its low toxicity and wide application, and it is still a challenge for developing highly sensitive and selective electrochemiluminescence (ECL) sensors based on the noble metal-free electrode. Hence, we designed an accurate ECL sensor for detecting trace H2O2 based on N-doped porous carbon containing Fe (Fe/N-C) nanocomposites, which were successfully synthesized by pyrolysis of NH2-MIL-101(Fe) metal-organic framework (MOF). Fe/N-C nanocomposite significantly improved the electron transfer process and enhanced the catalytic activity of ECL sensor for trace H2O2 detection. Fe/N-C nanocomposite significantly contributed in the conversion of H2O2 to superoxide radical, followed by the oxidation of luminal which enhanced the electrochemical luminescence signal. Predictably, the ECL sensing strategy at Fe/N-C nanocomposite electrode showed a satisfying linear range from 1 nM to 300 nM for H2O2 detection with limit of detection (LOD) as 0.93 nM (signal to noise ratio (S/N) = 3). Also, the ECL sensor was used to detect H2O2 in real water samples and renal epithelial 293T cells, which justified great promise for the practical ECL detection of H2O2.

Resistance to Helium Bubble Formation in Amorphous SiOC/Crystalline Fe Nanocomposite.

The management of radiation defects and insoluble He atoms represent key challenges for structural materials in existing fission reactors and advanced reactor systems. To examine how crystalline/amorphous interface, together with the amorphous constituents affects radiation tolerance and He management, we studied helium bubble formation in helium ion implanted amorphous silicon oxycarbide (SiOC) and crystalline Fe composites by transmission electron microscopy (TEM). The SiOC/Fe composites were grown via magnetron sputtering with controlled length scale on a surface oxidized Si (100) substrate. These composites were subjected to 50 keV He+ implantation with ion doses chosen to produce a 5 at% peak He concentration. TEM characterization shows no sign of helium bubbles in SiOC layers nor an indication of secondary phase formation after irradiation. Compared to pure Fe films, helium bubble density in Fe layers of SiOC/Fe composite is less and it decreases as the amorphous/crystalline SiOC/Fe interface density increases. Our findings suggest that the crystalline/amorphous interface can help to mitigate helium defect generated during implantation, and therefore enhance the resistance to helium bubble formation.

Optimized microstructure and impedance matching for improving the absorbing properties of core-shell C@Fe3C/Fe nanocomposites

The carbon coated core-shell C@Fe3C/Fe nanocomposites were prepared by plasma arc-discharging method. The core-shell and graphite network structures were obtained, which could improve the absorbing properties by optimizing the impedance matching and increase the internal reflections of the propagated microwave. By varying the coating thickness from 1.0 to 5.0 mm, the reflectivity of C@Fe3C/Fe nanocomposites prepared in 30% CH4 is less than −20 dB nearly in the whole range of 2–18 GHz. The minimum reflection loss value reaches −32.9 dB at 14.2 GHz and the effective bandwidth (<-10 dB) is from 12.1 to 17.2 GHz (d = 1.7 mm). The obtained network structured core-shell C@Fe3C/Fe absorber would be an attractive candidate for microwave absorbing materials for its low density, strong absorption, and broad bandwidth.

Large-scale synthesis and excellent microwave absorption of highly-dispersed Fe nanoparticles via RF thermal plasma

Spherical Fe nanoparticles (FeNPs) with diameter of ∼100 nm were prepared by evaporating carbonyl iron particles (CIPs) using RF thermal plasma in a large scale. The FeNPs presented smooth surface, good dispersity and excellent antioxidation performance, which could be homogeneously distributed in paraffin with a particle loading as high as 90 wt%. In comparison to the raw CIPs, the FeNPs showed enhanced resonance characteristics in both permittivity and permeability due to the particle size effect. It was found that the FeNPs/paraffin composite exhibited excellent microwave absorption in terms of small matching thickness and broad bandwidth. The percentage bandwidth with reflection loss ≤−10 dB for the Fe nanocomposite is larger than that for the carbonyl iron composite at any specified thickness in the range of 1.0 ∼ 2.5 mm. This work demonstrates that the synthesized FeNPs hold great promise for developing thin-layered absorbers with excellent microwave absorbing performance.

Integration of plasmonic effect into spindle-shaped MIL-88A(Fe): Steering charge flow for enhanced visible-light photocatalytic degradation of ibuprofen

High electron-hole separation efficiency and wide spectrum absorption are desired for improving the photocatalytic activity. In this research, we integrate plasmonic Ag/AgCl with a typical semiconductor-like metal-organic framework MIL-88A(Fe) to form Ag/AgCl@MIL-88A(Fe) (ACMA) nanocomposites by a facile one-pot solvothermal method. The results demonstrate that ACMA nanocomposites not only broaden the visible-light absorption of MOFs, but also greatly accelerate photo-induced charge transfer rate. EDS mapping and HRTEM results suggest that Ag/AgCl is uniformly and densely dispersed on the surface of MOF, which is beneficial for charge flow and expedites the charge migration. By virtue of the structural and compositional features, these unique ACMA nanocomposites perform excellent photocatalytic activity on ibuprofen (IBP) in terms of high degradation efficiency, high mineralization and excellent cycling stability. ACMA-2 (Fe:Ag = 2:1) displays highly efficient photocatalytic activity on IBP under visible light irradiation, and the corresponding photo-degradation rate is 10.8 and 40.4 folds higher than that of MIL-88A(Fe) and Ag/AgCl, respectively. Total organic carbon (TOC) removal of IBP photodegradation reaches 91% by the catalysis of ACMA-2. Combined with the electrochemical tests, quencher experiments and analysis of related degradation products identified by ion chromatography (IC) and LC-MS-MS, oxidation by superoxide radicals (O2−) as well as holes (h+) and electrons (e−) is the dominant degradation process in the photocatalytic degradation of IBP. This work provides a new perspective for the preparation of environment-stable and efficient MOF-based photocatalysts by steering charge flow.

Thermal decomposition and reducibility of silica-supported precursors of Cu, Fe and Cu–Fe nanoparticles

Cu–Fe nanocomposites are considered as ecofriendly and low-cost alternative to precious metal catalysts for selective hydrogenation of products derived from biomass and syngas. In this work, the catalytically active nanocomposites have been synthesized by supporting Cu and Fe precursors on a silica carrier using the novel procedure of consecutive incipient wetness impregnation and the method of deposition–precipitation using urea (DPU). The prepared silica-supported precursors are shown to decompose completely at temperatures as low as 300–350 °C, thus giving a possibility to obtain Fe and Cu–Fe oxide nanoparticles of the size 1–4 nm as isolated particles or their aggregates. Interaction of Fe and Cu species in the prepared nanoparticles has been revealed by the method of temperature-programmed reduction with hydrogen, which exhibited the Cu-enhanced reducibility of Fe3+ to Fe0 and stability to reoxidation for the metallic particles. Variations in the preparation procedures influence the reducibility and the interaction between Cu and Fe components resulting in considerable changes of the catalytic activity and selectivity in hydrogenation of unsaturated carbon bonds. Complete reduction to a metallic state was reached at 500 °C if the DPU preparation method was applied. The nanocomposites prepared by the DPU procedure provide the highest catalytic activity.

Fe3O4/MIL‐101(Fe) nanocomposite as an efficient and recyclable catalyst for Strecker reaction

A highly porous metal‐organic framework, MIL‐101(Fe), was prepared by a solvothermal method in the presence of amino‐modified Fe3O4@SiO2 nanoparticles, in order to achieve Fe3O4/MIL‐101(Fe) nanocomposite, which was characterized by XRD, FT‐IR, SEM, TEM, BET, and VSM. This hybrid magnetic nanocomposite was employed as heterogeneous catalyst for α‐amino nitriles synthesis through three‐component condensation reaction of aldehydes (ketones), amines, and trimethylsilyl cyanide in EtOH, at room temperature. The recoverability and reusability was admitted for the heterogeneous magnetic catalyst; no significant reduction of catalytic activity was observed even after five consecutive reaction cycles.

Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

Abstract In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N 2 adsorption-desorption, H 2 -TPR, NH 3 -TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N 2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N 2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH 3 -SCR (selective catalytic reduction of NO by NH 3 ) reaction.

Facile in situ growth of highly dispersed palladium on phosphotungstic-acid-encapsulated MIL-100(Fe) for the degradation of pharmaceuticals and personal care products under visible light

A simple, facile in situ reduction approach is reported for the synthesis of Pd-nanoparticle-decorated phosphotungstic acid (PTA)-MIL-100(Fe) nanocomposites (Pd-H3PW12O40-MIL-100(Fe), denoted Pd-PTA-MIL-100(Fe)). During the in situ synthesis, PTA is encapsulated into the matrix of MIL-100(Fe) and serves as a UV-switchable reducing agent, resulting in highly dispersed Pd NPs. Using the photocatalytic degradation of pharmaceuticals and personal care products as model reactions, the ternary Pd-PTA-MIL-100(Fe) hybrids exhibited enhanced photocatalytic activity compared with their foundation matrices, the binary PTA-MIL-100(Fe) nanocomposite. Based on photoelectrochemical analyses, the improved photocatalytic performance can be attributed to the well-known electronic conductivity of the Pd NPs, the fast electron transport of PTA, the intense visible-light absorption of MIL-100(Fe), and the matched energy levels of the three components: MIL-100(Fe), PTA, and Pd NPs. Importantly, almost no Fe and W ions were leached from the samples during the reaction, demonstrating the photostability of the Pd-PTA-MIL-100(Fe) composite. In addition, possible photocatalytic reactions mechanisms have also been investigated.

Enhanced Microwave Absorption Property of Fe Nanoparticles Encapsulated within Reduced Graphene Oxide with Different Thicknesses

Reduced graphene oxide (RGO)/Fe nanocomposites were synthesized by a facile one-step reduction reaction, using reduced graphene oxide and FeSO4·7H2O as raw materials. These RGO/Fe nanocomposites combine Fe nanoparticles with graphene in various thicknesses. The results show that the residual defects and groups in chemically reduced graphene oxide brought about defect polarization relaxation and groups’ electronic dipole relaxation, which both make the electromagnetic absorbing performance of RGO/Fe nanocomposites better than that of pure Fe nanoparticles. Most importantly, this paper reveals that graphene with different thicknesses has a great influence on the microwave-absorbing properties of the composites. There was serious agglomeration in RGO/Fe nanocomposites synthesized by thin graphene, while the graphene of a certain thickness could support the nanoparticles on its surface, thereby reducing the effect of agglomeration on the composite material and giving full play to dielectric loss properties of...

Synthesis of CdS-decorated MIL-68(Fe) nanocomposites: Efficient and stable visible light photocatalysts for the selective reduction of 4-nitroaniline to p-phenylenediamine in water

Visible-light-initiated organic transformations have received much attention because of low cost, relative safety, and environmental friendliness. In this work, a series of CdS-decorated MIL-68(Fe) nanocomposites (CdS-M68 NCs) have been prepared via a facile room-temperature photodeposition technique in a controlled manner. Importantly, the CdS-M68 NCs exhibit remarkably enhanced photoactivity toward selective reduction of 4-nitroaniline (4-NA) to p-phenylenediamine (PPD) in water under visible light irradiation (λ≥420nm) as compared to bare CdS and MIL-68(Fe), giving a 4-NA conversion of ∼100% after irradiation for 8min. The significantly enhanced photoactivity is attributed to the integrated factors of the effective transportation of the photogenerated electron-hole pairs and the enhanced visible light absorption intensity. Combining with trapping experiments and ESR analysis, it could be revealed that the photoexcited electrons and CO2− radicals should be the main active species in the present system. In addition, a possible photocatalytic reduction mechanism has been investigated.

A sandwich-like heterostructure of TiO2 nanosheets with MIL-100(Fe): A platform for efficient visible-light-driven photocatalysis

Hierarchical heterostructures with specific compositions, morphology and functionalities are important for applications in many fields such as catalysis, energy storage and conversion. Herein, hierarchical sandwich-like heterostructures were prepared by a self-assembly method of growing MIL-100(Fe) on host two dimensional (2D) TiO2 nanosheets (TiO2NS). The introduction of porous MIL-100(Fe) on TiO2NS improves the adsorption ability of nanocomposites owing to the porous tunnel adsorbing organic molecules and high surface area. In addition, the interfaces of TiO2NS and MIL-100(Fe) provide platforms for rapid photoexcited electrons transfer and enhance the photocatalytic activity of TiO2NS@MIL-100(Fe) nanocomposites. The resulting sandwich-like TiO2NS@MIL-100(Fe) nanocomposites with enhanced adsorption ability and superior separation of photogenerated electron-hole pairs exhibited improved photoactivity toward degradation of methylene blue dye (MB) under visible light (λ≥420nm). TiO2NS@MIL-100(Fe) nanocomposites offer an useful platform to integrate photocatalytic semiconductor and porous MOFs into hierarchical nanostructures with high surface areas and efficient electrons transfer for enhanced photocatalytic performance.

Preparation of Cu-Fe nanocomposites loaded diatomite and their excellent performance in simultaneous adsorption/oxidation of hydrogen sulfide and phosphine at low temperature

Abstract In the study, a variety of supported metal oxide adsorbents were evaluated for simultaneous adsorption/oxidation of hydrogen sulfide (H2S) and phosphine (PH3) from crude acetylene gas at low temperature (80 °C), and the materials were synthesized using incipient impregnation method. Test results showed that the Cu Fe nanocomposites/modified diatomite adsorbent (Cu Fe/MKL) was determined to be the most promising adsorbent for simultaneous removal of H2S and PH3. The removal efficiency of H2S and PH3 may have a strong connection to the variety and amounts of functional groups and active components available as well as calcination temperatures. When the copper and iron loading amounts were 10 wt% and 6 wt% at 450 °C, the Cu Fe/MKL adsorbent achieved the best removal efficiency and had the largest breakthrough adsorption capacity. It kept an impressive efficiency (100%) for 150 min and 60 min for H2S and PH3, respectively, at a relatively low reaction temperature of 80 °C and a GHSV of 10,000 h−1. The adsorbents were also characterized by different methods, such as FT-IR, BET, TGA, XRD, SEM, XPS and in-situ IR. FT-IR results showed that the adsorbents modification by hydrochloric acid can provide more O H, C O and C C groups, which may generate more unsaturated sites to promote the removal performance for H2S and PH3. BET results indicated that the addition of Cu Fe composites did not change the structure of diatomite and it was optimized for simultaneous adsorption/oxidation of H2S and PH3 when the pore size distribution was approximately 7–10 nm. Moreover, XRD and TGA results revealed that metal oxides were detected after calcination, and the main active components available should be Cu Fe nanocomposites. Furthermore, SEM images showed that iron species may play an important role to promote the dispersion of active components. In addition, in-situ IR and XPS analysis indicated that the exhaustion of sample may be determined by the loss of active components and the accumulations of products. It was considered that the excellent performance of adsorbents may be determined by the synergism of function groups, active components and dispersion capacity of them. However, because the components of diatomite were complex, the mechanism was difficult to investigate in this study.

Evaluation of iron–epoxy metal nanocomposite in glass fibre and Kevlar

ABSTRACTThis paper deals with the enrichment of the both mechanical and electrical properties of Kevlar and glass fibres, not including mounting the weight of the structure by adding the iron (Fe) nanocomposites with the epoxy resin. The Fe is mixed well with the epoxy to increase the mechanical constancy and the electrical property of the fibre by a non-covalent approach. The synthesis of metal nanocomposite with epoxy is done by the direct mixing method. The Kevlar and the glass fibre were taken as the samples for this study. The zinc oxide and epoxy were mixed simultaneously using a mechanical stirrer to give appropriate dispersion and adhesion without disturbing the hydrophobic performance of the epoxy, and the Fe powder and epoxy are added with a hardener in the ratio of 1:1:0.1. The results show that the mechanical property of the fibre increased with the decrease in the weight of the laminate when they are treated with the metal nanocomposite.

Facile synthesis of polypyrrole@metal-organic framework core-shell nanocomposites for dual-mode imaging and synergistic chemo-photothermal therapy of cancer cells.

In our work, we report a facile approach to fabricate well-dispersed polypyrrole@metal-organic framework (PPy@MOF) core-shell nanocomposites (NCs) with a polypyrrole (PPy) core and an MIL-100(Fe) shell. The adsorbed Fe(iii) ions on the as-fabricated PPy surface were utilized as reactive sites for further growth of the MIL-100(Fe) in the presence of trimesic acid (H3btc). The resulting NCs exhibited strong absorption in the near infrared (NIR) region and possessed an excellent photothermal efficiency of ∼40% resulting from the PPy core. The MOF structure based on Fe(iii) carboxylate materials held great ability for storage/delivery of the hydrophilic anti-cancer drug, doxorubicin (DOX). The released DOX continuously increased due to the damage of the shell at low pH values. When the DOX-loaded PPy@MIL-100(Fe) NCs were exposed to NIR irradiation, owing to the heat produced by the NCs, the local temperature increased, resulting in a faster release of DOX from the MIL-100(Fe) shell. Furthermore, PPy@MIL-100(Fe) NCs were successfully employed for dual-mode magnetic resonance imaging (MRI)/photoacoustic imaging (PAI) and synergistic chemo-photothermal therapy of cancer cells. Therefore, our work could encourage further study in the construction of a multifunctional platform using different MOF nanomaterials for cancer theranostics.