Fe-based Materials Research Articles

Construction of Fe-based amorphous active surface microenvironment and its synergistic Fenton-like treatment of organic pollutants

Fe-based amorphous materials with the superiorities of high efficiency and low Fe sludge secondary pollution can be seen as a potential alternative to Fenton catalysts. However, catalyst deactivation on the catalyst surface hinders the sustainability of high degradation activity. In this study, the degradation capabilities of FeBCCr amorphous alloys in methylene blue (MB) solution by Fenton-like method were explored. The optimum (Fe81B10C9)99Cr1 ribbon with a more uniform Fe3B-like amorphous structure, which exhibits a thin and easily-peeled oxide layer, provides unique dynamic self-renewing to obtain excellent efficiency and recyclability. The degradation rate with 0.05 g/L (Fe81B10C9)99Cr1 ribbon reached 0.248 min−1 and the recyclability reached a charming record of over 90 times with a dosage of 0.1 g ribbon. The activation energy of (Fe81B10C9)99Cr1 ribbon (12.97 kJ mol−1) was found to be superior to that of most metallic catalysts. More importantly, the boron-rich film in the interfacial region can both retard further oxidation of iron and provides a channel for electron transmission, which can contribute to the persistence of a highly active microenvironment with more Fe(Ⅱ) sites and highly utilization of H2O2. The limit segmentation method has verified the good performance in both heterogeneous and homogeneous reactions. This study introduces a strategy for designing high-performance non-noble metallic catalysts through cluster structure regulation, which provides a novel Fenton-like amorphous material with long recyclability of high degradation activity for water remediation.

Study of helium diffusion in yttria: A multiscale approach based on the density functional theory and kinetic Monte Carlo, with transmission electron microscopy and thermo-desorption spectroscopy

A known issue for future nuclear reactors is helium accumulation inside the steel structure materials, responsible for structural issues such as embrittlement and cracking. One possible solution is using new types of reinforced steel, such as oxide dispersion strengthened (ODS) steel. It consists of adding oxide nanoparticles to the Fe-based material, especially yttrium oxide (yttria, Y2O3), improving its properties. Therefore, one first step is understanding the helium diffusion inside this system. Very little is known about helium inside yttria, with most studies being theoretical ones. Based on this context, this work proposes a combined theoretical and experimental multiscale approach to investigate helium diffusion inside yttria.The theoretical approach starts with the density functional theory, used to model the atomic yttria cell and determine helium insertion sites. The transitions between the sites were described using the Nudged Elastic Bond (NEB) method. Kinetic Monte Carlo was then employed to obtain the interstitial diffusion coefficient expression for the first time for this material. It showed a limited diffusion at temperatures below 600 K, which may indicate a tendency for He to be blocked in the oxide. Then, the charged vacancies were explored. It showed that the vacancy further reduces helium diffusion. Finally, it was demonstrated that helium spreads across different vacancies and interstitial sites.The experimental part involved implanting helium ions at 50 keV in samples with nanometric or micrometric grains. Then, the specimens were characterised with transmission electron microscopy (TEM) and thermo-desorption spectroscopy (TDS) techniques. TEM did not evidence detectable bubbles even at the highest studied fluence (1 × 1016 cm−2). The TDS highlighted different mechanisms for helium diffusion and the grain size's role, providing a novel model for diffusion coefficient calculation based on interstitial diffusion.

Analysis of the Structure of Heavy Ion Irradiated LaFeO3 Using Grazing Angle X-ray Absorption Spectroscopy.

Crystalline ceramics are candidate materials for the immobilization of radionuclides, particularly transuranics (such as U, Pu, and Am), arising from the nuclear fuel cycle. Due to the α-decay of transuranics and the associated recoil of the parent nucleus, crystalline materials may eventually be rendered amorphous through changes to the crystal lattice caused by these recoil events. Previous work has shown irradiation of titanate-based ceramics to change the local cation environment significantly, particularly in the case of Ti which was shown to change from 6- to 5-fold coordination. Here, this work expands the Ti-based study to investigate the behavior in Fe-based materials, using LaFeO3 as an example material. Irradiation was simulated by heavy ion implantation of the bulk LaFeO3 ceramic, with the resulting amorphous layer characterized with grazing angle X-ray absorption spectroscopy (GA-XAS). Insights into the Fe speciation changes exhibited by the amorphized surface layer were provided through quantitative analysis, including pre-edge analysis, and modeling of the extended X-ray absorption fine structure (EXAFS), of the GA-XAS data.

Synergizing Fe2O3 Nanoparticles on Single Atom Fe-N-C for Nitrate Reduction to Ammonia at Industrial Current Densities.

The electrochemical reduction of nitrates (NO3 -) enables a pathway for the carbon neutral synthesis of ammonia (NH3), via the nitrate reduction reaction (NO3RR), which has been demonstrated at high selectivity. However, to make NH3 synthesis cost-competitive with current technologies, high NH3 partial current densities (jNH3) must be achieved to reduce the levelized cost of NH3. Here, the high NO3RR activity of Fe-based materials is leveraged to synthesize a novel active particle-active support system with Fe2O3 nanoparticles supported on atomically dispersed Fe-N-C. The optimized 3×Fe2O3/Fe-N-C catalyst demonstrates an ultrahigh NO3RR activity, reaching a maximum jNH3 of 1.95 A cm-2 at a Faradaic efficiency (FE) for NH3 of 100% and an NH3 yield rate over 9 mmol hr-1 cm-2. Operando XANES and post-mortem XPS reveal the importance of a pre-reduction activation step, reducing the surface Fe2O3 (Fe3+) to highly active Fe0 sites, which are maintained during electrolysis. Durability studies demonstrate the robustness of both the Fe2O3 particles and Fe-Nx sites at highly cathodic potentials, maintaining a current of -1.3 A cm-2 over 24 hours. This work exhibits an effective and durable active particle-active support system enhancing the performance of the NO3RR, enabling industrially relevant current densities and near 100% selectivity.

Robust Activity and Stability of P-Doped Fe-Carbon Composites Derived from MOF for Bromate Reduction.

Iron-based materials are effective for the reductive removal of the disinfection byproduct bromate in water, while the construction of highly stable and active Fe-based materials with wide pH adaptability remains greatly challenging. In this study, highly dispersed iron phosphide-decorated porous carbon (Fe2P(x)@P(z)NC-y) was prepared via the thermal hydrolysis of Fe@ZIF-8, followed by phosphorus doping (P-doping) and pyrolysis. The reduction performances of Fe2P(x)@P(z)NC-y for bromate reduction were evaluated. Characterization results showed that the Fe, P, and N elements were homogeneously distributed in the carbonaceous matrix. P-doping regulated the coordination environment of Fe atoms and enhanced the conductivity, porosity, and wettability of the carbonaceous matrix. As a result, Fe2P(x)@P(1.0)NC-950 exhibited enhanced reactivity and stability with an intrinsic reduction kinetic constant (kint) 1.53-1.85 times higher than Fe(x)@NC-950 without P-doping. Furthermore, Fe2P(0.125)@P(1.0)NC-950 displayed superior reduction efficiency and prominent stability with very low Fe leaching (4.53-22.98 μg L-1) in a wide pH range of 4.0-10.0. The used Fe2P(0.125)@P(1.0)NC-950 could be regenerated by phosphating, and the regenerated Fe2P(0.125)@P(1.0)NC-950 maintained 85% of its primary reduction activity after five reuse cycles. The study clearly demonstrates that Fe2P-decorated porous carbon can be applied as a robust and stable Fe-based material in aqueous bromate reduction.

Double-Shelled Fe-Fe3C Nanoparticles Embedded on a Porous Carbon Framework for Superior Lithium-Ion Half/Full Batteries.

Cost-effective and environmentally friendly Fe-based active materials offer exceptionally high energy capacity in lithium-ion batteries (LIBs) due to their multiple electron redox reactions. However, challenges, such as morphology degradation during cycling, cell pulverization, and electrochemical stability, have hindered their widespread use. Herein, we demonstrated a simple salt-assisted freeze-drying method to design a double-shelled Fe/Fe3C core tightly anchored on a porous carbon framework (FEC). The shell consists of a thin Fe3O4 layer (≈2 nm) and a carbon layer (≈10 nm) on the outermost part. Benefiting from the complex nanostructuring (porous carbon support, core-shell nanoparticles, and Fe3C incorporation), the FEC anode delivered a high discharge capacity of 947 mAh g-1 at 50 mA g-1 and a fast-rate capability of 305 mAh g-1 at 10 A g-1. Notably, the FEC cell still showed 86% reversible capacity retention (794 mAh g-1 at 50 mA g-1) at a high cycling temperature of 80 °C, indicating superior structural integrity during cycling at extreme temperatures. Furthermore, we conducted a simple solid-state fluorination technique using the as-prepared FEC sample and excess NH4F to prepare iron fluoride-carbon composites (FeF2/C) as the positive electrode. The full cell configuration, consisting of the FEC anode and FeF2/C cathode, reached a remarkable capacity of 200 mAh g-1 at a 20 mA g-1 rate or an energy density of approximately 530 Wh kg-1. Thus, the straightforward and simple experimental design holds great potential as a revolutionary Fe-based cathodic-anodic pair candidate for high-energy LIBs.

Design of Fe-based metal organic framework derived catalysts: Remediation of nitrate contamination and action in polluted surface water

Removing nitrate from surface water is a constant challenge due to its high stability. While electrochemical treatment, a clean and renewable energy source, is promising, most strategies focus solely on energy conversion without considering treatment efficiency and practical application prospects. In this study, a Fe-based MOF derived material MC was synthesized by combining the process of hydrothermal and pyrolysis using Fe-MOF as the raw material to investigate the viability of nitrate reduction. The MC electrode exhibits 91.3 % NO3- removal and 44.9 % current efficiency in 180 min. The selectivity of ammonia is 90.6 % without Cl- and the selectivity of N2 is 89.9 % with Cl-. The excellent behavior of MC is attributed to the layered structure of dispersed Fe-based nanocluster and interconversion of Fe three valence states, which are conducive to mass transfer and electron transfer, respectively. The Layered Fe-based electrode material MC is a cost-effective, high-efficiency and stabilized electrode catalyst capable of treating water in a wide pH range and broad hardness. It maintained excellent stability over ten cycles and was used to remove nitrate, TN, and COD from polluted surface water, proving to be an environmentally friendly option for the deep purification of polluted surface water.

Construction of high performance fuel electrode in solid oxide electrolysis cells by tuning the surface oxygen defect to promote electrochemical reduction of CO2

B-site Co–Fe-based perovskite materials have shown potential as ceramic cathodes in solid oxide electrolysis cells (SOECs) for direct CO2 electrolysis. Nevertheless, their operational utilization is constrained by insufficient catalytic activity and durability in pure CO2. In this work, F− doping and A-site deficiency strategies are proposed and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), F-doped La0.6Sr0.4Co0.2Fe0.8F0.1O2.9 (LSCFF) and A-site deficiency combined with F-doped (La0.6Sr0.4)0.95Co0.2Fe0.8F0.1O2.9 (LSCFF95) are prepared as cathode materials for CO2 electrolysis. After doping with F−, the valence states of both Co and Fe elements decrease, while generating more oxygen vacancies. With the further introduction of A-site deficiency, the valence states further decrease, resulting in more oxygen vacancies. The enhancement of oxygen vacancies leads to an improvement in the oxygen surface exchange coefficient (kchem) and the bulk diffusion coefficient (Dchem) of LSCFF and LSCFF95 materials. At 800 °C, kchem of LSCFF and LSCFF95 reach 24.21 × 10−4 and 33.54 × 10−4 cm s−1, respectively, which are 51% and 110% higher than the value of 16.03 × 10−4 cm s−1 for LSCF. Meanwhile, the Dchem values of LSCFF and LSCFF95 are measured to be 37.52 × 10−5 and 47.81 × 10−5 cm2 s−1, respectively. These values are 49% and 90% higher than the value of 25.22 × 10−5 cm2 s−1 for LSCF. Consequently, F− doping and A-site deficiency significantly increase the electrochemical performance. For example, F− doping decreases the polarization resistance (Rp) value of the SOEC with LSCF cathode from 0.19 Ω cm2 to 0.13 Ω cm2 at 800 °C. Furthermore, when the A-site deficiency is introduced, the Rp value is further reduced to 0.11 Ω cm2. Therefore, the SOEC with the LSCFF95 cathode exhibits excellent performance. Specifically, it has demonstrated an impressively high current density of 2.85 A cm−2 at 800 °C and 1.5 V, and has exhibited exceptional durability over prolonged operation.

Creation of flexible spin-caloritronic material with giant transverse thermoelectric conversion by nanostructure engineering

Functional materials such as magnetic, thermoelectric, and battery materials have been revolutionized through nanostructure engineering. However, spin caloritronics, an advancing field based on spintronics and thermoelectrics with fundamental physics studies, has focused only on uniform materials without complex microstructures. Here, we show how nanostructure engineering enables transforming simple magnetic alloys into spin-caloritronic materials displaying significantly large transverse thermoelectric conversion properties. The anomalous Nernst effect, a promising transverse thermoelectric phenomenon for energy harvesting and heat sensing, has been challenging to utilize due to the scarcity of materials with large anomalous Nernst coefficients. We demonstrate a remarkable ~ 70% improvement in the anomalous Nernst coefficients (reaching ~ 3.7 µVK−1) and a significant ~ 200% enhancement in the power factor (reaching ~ 7.7 µWm−1K−2) in flexible Fe-based amorphous materials by nanostructure engineering without changing their composition. This surpasses all reported amorphous alloys and is comparable to single crystals showing large anomalous Nernst effect. The enhancement is attributed to Cu nano-clustering, facilitating efficient transverse thermoelectric conversion. This discovery advances the materials science of spin caloritronics, opening new avenues for designing high-performance transverse thermoelectric devices for practical applications.

Nano zerovalent Fe did not reduce metal(loid) leaching and ecotoxicity further than conventional Fe grit in contrasting smelter impacted soils: A 1-year field study

The majority of the studies on nanoscale zero-valent iron (nZVI) are conducted at a laboratory-scale, while field-scale evidence is scarce. The objective of this study was to compare the metal(loid) immobilization efficiency of selected Fe-based materials under field conditions for a period of one year. Two contrasting metal(loid) (As, Cd, Pb, Zn) enriched soils from a smelter-contaminated area were amended with sulfidized nZVI (S-nZVI) solely or combined with thermally stabilized sewage sludge and compared to amendment with microscale iron grit. In the soil with higher pH (7.5) and organic matter content (TOC = 12.7 %), the application of amendments resulted in a moderate increase in pH and reduced As, Cd, Pb, and Zn leaching after 1-year, with S-nZVI and sludge combined being the most efficient, followed by iron grit and S-nZVI alone. However, the amendments had adverse impacts on microbial biomass quantity, S-nZVI being the least damaging. In the soil with a lower pH (6.0) and organic matter content (TOC = 2.3 %), the results were mixed; 0.01 M CaCl2 extraction data showed only S-nZVI with sludge as remaining effective in reducing extractable concentrations of metals; on the other hand, Cd and Zn concentrations were increased in the extracted soil pore water solutions, in contrast to the two conventional amendments. Despite that, S-nZVI with sludge enhanced the quantity of microbial biomass in this soil. Additional earthworm avoidance data indicated that they generally avoided soil treated with all Fe-based materials, but the presence of sludge impacted their preferences somewhat. In summary, no significant differences between S-nZVI and iron grit were observed for metal(loid) immobilization, though sludge significantly improved the performance of S-nZVI in terms of soil health indicators. Therefore, this study indicates that S-nZVI amendment of soils alone should be avoided, though further field evidence from a broader range of soils is now required.

FeSe2 and Its Composites for Pollutants Removal: Synthesis, Mechanisms, and Application Potential.

In recent years, the research of FeSe2 and its composites in environmental remediation has been gradually carried out. And the FeSe2 materials show great catalytic performance in photocatalysis, electrocatalysis, and Fenton-like reactions for pollutants removal. Therefore, the studies and applications of FeSe2 materials are reviewed in this work, including the common synthesis methods, the role of Fe and Se species as well as the catalyst structure, and the potential for practical environmental applications. Hereinto, it is worth noting in particular that the lower-valent Se (Se2-), unsaturated Se (Se-), and Se vacancies (VSe) can play different roles in promoting pollutants removal. In addition, the FeSe2 material also demonstrates high stability, reusability, and adaptability over a wider pH range as well as universality to different pollutants. In view of the overall great properties and performance of FeSe2 materials compared with other typical Fe-based materials, it deserves and needs further research. And finally, this paper presents some challenges and perspectives in future development, looking forward to providing helpful guidance for the subsequent research of FeSe2 and its composites for environmental application.

Comparative study of electromagnetic functional epoxy composites filled with Fe-based materials

Comparative study of electromagnetic functional epoxy composites filled with Fe-based materials

Electroactive heterojunctions of iron-based compounds in oxygen evolution reaction—Insight into synergy and mechanism

This research addresses the inherent challenges of low catalytic activity and stability often associated with Oxygen Evolution Reaction (OER) catalysts. We designed composites with outstanding electrocatalytic performance. The methodology is characterized by low-temperature operation and environmentally friendly substrates. We have successfully fostered a synergistic interplay between Fe and oxygen, carbon and nickel, respectively. Fabricated material composed of three different heterojunctions triggered the stability of the catalyst and facilitated efficient charge transfer in OER. Our optimized catalyst (Fe/Ni_3.0h), emerges as a promising candidate for practical applications, exhibiting an overpotential of 310 mV, a Tafel slope of 37 mV/dec, and a potential retention of 98.8 % which is a 50 % lower drop in respect to commercial RuO2. Therefore, our approach underlines the substantial influence of conductive Fe-based materials: FeNi3, Fe3C, and Fe3O4 on OER performance with revealed comprehensive mechanism via ex-situ XRD and Mössbauer spectroscopy analyses.

Black-Fe2O3 Polyhedron-Assembled 3D Film Electrode With Enhanced Conductivity and Energy Density for Aqueous Solid-State Energy Storage

Abstract The construction of advanced Fe2O3 materials with high energy density for energy storage faces challenges due to the defects of conventional widely known red-brown Fe2O3 such as poor electronic conductivity and insufficient physical/chemical stability. Unlike previous works, we successfully synthesized a novel black-Fe2O3 (B-Fe2O3) thin film electrode by adopting a simple hydrothermal strategy. Physical characterizations indicate that the as-made B-Fe2O3 product is composed of polyhedrons (mainly exhibit four to eight sides) with a micrometer grade size range. Besides, the Fe-based thin film electrode with this 3D structure has a stronger affinity and high electronic conductivity. As anode of aqueous solid-state energy storage devices, the as-synthesized B-Fe2O3 film electrode exhibits excellent volume energy density of 14.349 kWh m−3 at a power density of 1609 kW m−3, which is much higher than the best result of previous works (∼8 kWh m−3). This study may provide new insights into the development of the Fe2O3 series on developing high-efficiency Fe-based anode materials for solid-state energy storage.

Insights into the Phase Purity and Storage Mechanism of Nonstoichiometric Na3.4 Fe2.4 (PO4 )1.4 P2 O7 Cathode for High-Mass-Loading and High-Power-Density Sodium-Ion Batteries.

Mixed-anion-group Fe-based phosphate materials, such as Na4 Fe3 (PO4 )2 P2 O7 , have emerged as promising cathode materials for sodium-ion batteries (SIBs). However, the synthesis of pure-phase material has remained a challenge, and the phase evolution during sodium (de)intercalation is debating as well. Herein, a solid-solution strategy is proposed to partition Na4 Fe3 (PO4 )2 P2 O7 into 2NaFePO4 ⋅ Na2 FeP2 O7 from the angle of molecular composition. Via regulating the starting ratio of NaFePO4 and Na2 FeP2 O7 during the synthesis process, the nonstoichiometric pure-phase material could be successfully synthesized within a narrow NaFePO4 content between 1.6 and 1.2. Furthermore, the proposed synthesis strategy demonstrates strong applicability that helps to address the impurity issue of Na4 Co3 (PO4 )2 P2 O7 and nonstoichiometric Na3.4 Co2.4 (PO4 )1.4 P2 O7 are evidenced to be the pure phase. The model Na3.4 Fe2.4 (PO4 )1.4 P2 O7 cathode (the content of NaFePO4 equals 1.4) demonstrates exceptional sodium storage performances, including ultrahigh rate capability under 100 C and ultralong cycle life over 14000 cycles. Furthermore, combined measurements of ex situ nuclear magnetic resonance, in situ synchrotron radiation diffraction and X-ray absorption spectroscopy clearly reveal a two-phase transition during Na+ extraction/insertion, which provides a new insight into the ionic storage process for such kind of mixed-anion-group Fe-based phosphate materials and pave the way for the development of high-power sodium-ion batteries.

Review on Fe-based double perovskite cathode materials for solid oxide fuel cells

As a clean and efficient energy conversion device, solid oxide fuel cells have been garnering attention due to their environmentally friendly and fuel adaptability. Consequently, they have become one of the current research directions of new energy. The cathode, as the electrochemical reaction site of an oxidation atmosphere in solid oxide fuel cells, plays a key role in determining the output performance. In recent years, the development of double perovskite cathode materials with mixed ionic and electronic conductors has made significant progress in intermediate-temperature (600-800 °C) fuel cells. These materials have the potential to deliver higher power densities and improved stability, making them promising candidates for future fuel cell applications. The Fe-based double perovskite structure cathode material has gained extensive attention due to its adjustable crystal structure and performance, as it has A(A’) or B(B’) positions in its AA’BB’O6 structure. This material has several advantages, such as high oxygen catalytic activity, low thermal expansion coefficient, and compatibility with the thermal expansion of the electrolyte. An increasing number of researchers have been exploring the performance reaction mechanism of double perovskite by modifying and adjusting its material microstructure, crystal structure, and electronic structure. In this paper, the research progress of LnBaFe2O5 and Sr2Fe2-xMoxO6 double perovskite cathode materials is reviewed to highlight the effects of various modification methods developed on electrochemical performance of these materials. Furthermore, the potential future research directions of double perovskite cathode materials are prospected.

Monolithic metal-based/porous carbon nanocomposites made from dissolved cellulose for use in electrochemical capacitor

Porous metal-based carbon nanocomposites, with a monolithic shape, were prepared by a one-pot synthesis from dissolved cellulose and metallic salts using a simple, cheap, and environmentally friendly route. Their potential performances as electrochemical capacitors were tested with three metal precursors (M = Cu, Mn, and Fe) with two loadings and in an asymmetric cell for the Fe-based carbon material. Interestingly, here soluble metal precursors were not deposited on a hard cellulose template but mixed in a precooled concentrated NaOH solution where cellulose was previously dissolved, allowing for a good dispersion of the metallic species. After a freezing step where concomitant cellulose regeneration and pore ice-templating phenomena took place, followed by a carbonization step, the mixture led to a porous carbon monolith embedding well-dispersed metal-based nanoparticles having a diameter below 20 nm and present as metallic, oxide, or carbide phase(s) according to the element M. These materials were characterized by different physicochemical techniques and electrochemical tests. Their performances as supercapacitors are discussed in light of the specific behaviour of the metal-based phase and its influence on the carbon matrix properties such as mesopore formation and carbon graphitization. An asymmetric energy storage cell assembled with a Fe-based carbon electrode against a carbon xerogel electrode derived from a phenolic resin shows specific energy and power of 18.3 Wh kg−1 at 5 mA cm−2 and 1.6 kW kg−1 at 25 mA cm−2, respectively.

Structure, soft magnetic properties of Fe-based magnetic composites and its practical application

A multi-stage technique for applying insulating coatings to metal powder particles has been developed in order to create a new class of Fe-based soft magnetic materials with improved characteristics. The density value calculated from the data of X-ray diffraction analysis is approximately 3 % higher than the experimentally measured values, which are 7.4–7.45 g/cm3. The low porosity of the composites is confirmed by the SEM and EDX results. The proposed method of encapsulation of iron powder with an oxide layer is a highly economical method for applying coatings of various chemical compositions to metal powders, and can be widely used in practice to obtain electrical materials. Comprehensive studies of the properties of the obtained samples of powder composite materials based on ABC100.30 iron, the particles of which are encapsulated with phosphorus oxide, have been carried out. It has been established that in a field of 1.5 T, the losses at a frequency of 1 kHz decrease 10 times with an increase in the thickness to 30 nm. The synthesized materials are recommended for use in the development of various types of high-frequency electric motors, generators, chokes, magnetic circuits and electrodes for high-frequency welding and other applications.

Fe-Zn alloy, a new biodegradable material capable of reducing ROS and inhibiting oxidative stress.

Fe-based biodegradable materials have attracted significant attention due to their exceptional mechanical properties and favorable biocompatibility. Currently, research on Fe-based materials mainly focuses on regulating the degradation rate. However, excessive release of Fe ions during material degradation will induce the generation of reactive oxygen species (ROS), leading to oxidative stress and ferroptosis. Therefore, the control of ROS release and the improvement of biocompatibility for Fe-based materials are very important. In this study, new Fe-Zn alloys were prepared by electrodeposition with the intention of using Zn as an antioxidant to reduce oxidative damage during alloy degradation. Initially, the impact of three potential degradation ions (Fe2+, Fe3+, Zn2+) from the Fe-Zn alloy on human endothelial cell (EC) activity and migration ability was investigated. Subsequently, cell adhesion, cell activity, ROS production and DNA damage were assessed at various locations surrounding the alloy. Finally, the influence of different concentrations of Zn2+ in the medium on cell viability and ROS production was evaluated. High levels of ROS exhibited evident toxic effects on ECs and promoted DNA damage. As an antioxidant, Zn2+ effectively reduced ROS production around Fe and improved the cell viability on its surface at a concentration of 0.04 mmol/l. These findings demonstrate that Fe-Zn alloy can attenuate the ROS generated from Fe degradation thereby enhancing cytocompatibility.

Facile synthesis of Fe-based metal-organic frameworks from Fe2O3 nanoparticles and their application for CO2/N2 separation.

A facile approach was employed to fabricate MIL-100(Fe) materials from Fe2O3 nanoparticles through a conventional hydrothermal reaction without the presence of HF and HNO3. Effects of trimesic acid content in the reaction system on the quality and CO2/N2 separation performance of the as-prepared MIL-100(Fe) samples were investigated. Using 1.80 g of trimesic acid in the reaction system yielded the sample M-100Fe@Fe2O3#1.80, which proved to be the optimal sample. This choice struck a balance between the amount of required trimesic acid and the quality of the resulting material, resulting in a high yield of 81% and an impressive BET surface area of 1365.4 m2·g-1. At 25 °C and 1 bar, M-100Fe@Fe2O3#1.80 showed a CO2 adsorption capacity of 1.10 mmol·g-1 and an IAST-predicted CO2/N2 selectivity of 18, outperforming conventional adsorbents in CO2/N2 separation. Importantly, this route opens a new approach to utilizing Fe2O3-based waste materials from the iron and steel industry in manufacturing Fe-based MIL-100 materials.