FeCo Nanoparticles Research Articles

Mechanochemical synthesis of FeCo nanoalloys

The Iron-Cobalt Nanoalloys (ICNAs) were synthesized by co-reduction of the mixture of FeCl2.4H2O and CoCl2.6H2O salts and also in the chemical reduction of iron(II) bis(oxalate)cobaltate pentahydrate complex by aluminum nanoparticles in the solid-state at room temperature. Aluminum nanoparticles were prepared by a novel wire drawing method in the presence of lubricating oil. The products were characterized by IR, XRD, FESEM, EDX and VSM. The absorption bands do not appeared in FTIR spectra of FeCo nanoalloys (ICNAs) while, the spectra of precursor show all the absorption bands of the corresponding complex and salts. The X-ray diffraction pattern results show the presence of two phases unreacted aluminum and FeCo in ICNAs. The weight fraction of FeCo nanoparticles are calculated by the Rietveld method. Quantitative XRD analysis of FeCo-Al (S1) shows a weight fraction of 89.82% FeCo and unreacted aluminum 10.18% also, calculation in FeCo-Al (S2) shows weight fraction FeCo and unreacted aluminum 78.50 and 21.50% respectively. FESEM image of S1 and S2 show maximum particles size distribution in the region of 60nm to 100nm and 40nm to 80nm respctively. The hysteresis loop of S1 and S2 show magnetic saturation 101.8900emu/g and 39.6442emu/g respectively.

Bamboo-like nitrogen-doped carbon nanotubes directly grown from commercial carbon black for encapsulating FeCo nanoparticles as efficient oxygen reduction electrocatalysts

Efficient methods for preparing carbon nanotube (CNT)-confined metal catalysts are of great significance for electrocatalysis. Hence, in this study, Fe and Co promoters were added to the precursors of commercial carbon black and melamine to form N-doped CNTs confined bimetallic catalysts (FeCo@N-CNTs) via in situ pyrolysis. The FeCo@N-CNT catalysts exhibited a bamboo-like morphology with FeCo alloy nanoparticles encapsulated in the CNTs and high activity toward the oxygen reduction reaction, with a half-wave potential of 0.864 mV, higher than that of commercial Pt/C (0.827 mV) in alkaline solutions. The catalytic performance is attributable to the synergistic effects between the FeCo alloy and N-doped CNT structure. Moreover, the confinement of the FeCo nanoparticles inside the CNTs imparted the prepared catalysts with resistance to methanol poisoning and long-term stability. This versatile method of synthesizing CNTs directly from carbon black provides a new strategy for preparing high-performance non-precious-metal-based N-doped CNT catalysts for practical fuel cell applications.

Optimizing Reversible Exsolution and Phase Transformation in Double Perovskite Sr2Fe1.5-xCoxMo0.5O6-δ Electrodes for High-Performance Symmetric Solid Oxide Cells.

Double perovskite (DP) oxides are promising electrode materials for symmetric solid oxide cells (SSOCs) due to their excellent electrochemical activity and stability. B-site cation doping in DP oxides affects the reversibility ofphase transformation and exsolution, which plays a crucial role in the catalyst recovery. Yet, few studies have been conducted on this topic. In this study, the Sr2Fe1.5-xCoxMo0.5O6-δ (CSFM, x = 0, 0.1, 0.3, 0.5) DP system demonstrates modulated exsolution and phase transformation reversibility by manipulating the oxygen vacancy concentration. The correlation between Co-doping level and oxygen vacancy concentration is investigated to optimize the exsolution and phase transformation properties. Sr2Fe1.2Co0.3Mo0.5O6-δ (3CSFM) exhibits reversible transformation between DP and Ruddlesden-Popper phases with a high density of exsolved CoFe nanoparticles under redox atmospheres. The quasi-symmetric cell with 3CSFM shows a peak power density of 1.27Wcm-2 at 850°C in H2 fuel cell mode and a current density of 2.33Acm-2 at 1.6V and 800°C in H2O electrolysis mode. The 3CSFM electrode exhibits robust stability during continuous operation for ≈700h. These results demonstrate the significant role of B-site doping in designing DP materials capable of dynamic phase transformation in diverse environments.

Boron-doped diamond composites for durable oxygen evolution

The urgent need to develop efficient, durable, and cost-effective oxygen evolution reaction (OER) catalysts for energy conversion and storage has prompted extensive research. Currently available commercial noble metal-based OER catalysts are expensive and exhibit limited long-term stability. In this study, boron-doped diamond composites (BDDCs) consisting of CoFe and CoFe2C nanoparticles supported by boron-doped diamond (BDD) particles have been prepared. The BDDC catalyst, prepared through a straightforward annealing process, exhibits exceptional durability (up to 72 h at 10 mA cm−2), a low overpotential (306 mV at 10 mA cm−2), and modest Tafel slope (58 mV dec-1). The coherent interfaces between CoFe/CoFe2C nanoparticles and the BDD substrate are essential for enhancing the OER performance. The fabrication method and composite structures presented in this study may facilitate the design and production of promising catalysts.

Ultrasensitive detection of mycotoxins using a novel single-Atom, CRISPR/Cas12a-Based nanozymatic colorimetric biosensor

Aflatoxin B1 (AFB1) is a typical mycotoxin in cereals, posing a significant threat to the ecology and public health. Overall, the development of nanozymatic sensors with good specificity, high sensitivity, and a clear catalytic mechanism seems to be a challenge for CRISPR/Cas detection of non-nucleic acid targets. In this study, a series of Fe-N-C single-atom enzymes (SAzymes) and Fe-Co magnetic nanoparticles (MNPs) were synthesized via pyrolysis. Fe-N-C SAzymes with high peroxidase-mimetic activity were successfully utilized as TMB chromogenic catalysts for detecting AFB1 via the CRISPR/Cas12a colorimetric aptamer sensor. In the absence of the AFB1 target, its aptamer bound to crRNA and activated the trans-cleavage activity of Cas12a, indiscriminately cutting single-stranded DNA and releasing significant amounts of Fe-N-C SAzymes into the supernatant, which catalyzed the change of TMB to blue. The synthesized Fe-Co MNPs not only effectively reduced the background signal but also significantly reduced the assay cost. This study combined SAzymes with CRISPR/Cas12a technology for the first time for non-nucleic acid target detection. The combination of Fe-N-C SAzymes’ high catalytic activity and stability, and the CRISPR/Cas12a system’s high specificity and signal amplification, significantly improved the detection system’s sensitivity and specificity, enabling the detection of other targets by substituting the aptamers. Additionally, the potential active sites and catalytic mechanism of Fe-N-C SAzymes were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) simulations. This scheme provides a general method for constructing high-density Fe-N-C SAzymes and offers both experimental and theoretical guidance for understanding their catalytic mechanism.

A feasible method to prepare yolk@shell nanoreactor with multiple cores and enhanced Fenton-like performance by confinement effect

At present, yolk@shell nanoreactor has drawn much attention in Fenton reaction, since the degradation rate could be accelerated by confinement effect, and metal leaching could be suppressed under the shell protection. To further improve the performance of traditional yolk@shell nanoreactor with single core, in this work, a yolk@shell nanoreactor with multiple CoFe nanoparticles as cores and nitrogen-atom doped carbon (NC) as shell was prepared. In peroxymonosulfate (PMS)-based Fenton-like reaction, 93.8 % of degradation efficiency was realized within 30 min over CoFe@NC, much better than the reference broken CoFe@NC (B-CoFe@NC), confirming the positive function of integrated yolk@shell structure. Based on the radical trapping experiment, 1O2 was the most important reactive oxygen species in CoFe@NC, while SO4•- played a dominated role in B-CoFe@NC, reflecting the different catalytic mechanism in these two catalysts. To reveal the confinement effect, electron paramagnetic resonance analysis was carried out to trace the 1O2 source. And they were originated from SO4•- and •OH with high concentrations inside the yolk@shell CoFe@NC nanoreactor. This study provided a novel method to construct yolk@shell nanoreactor with multiple cores and gave a novel insight on enhanced Fenton-like performance via confinement effect.

FeCo@hydrochar nanocomposites as efficient peroxymonosulfate activator for organic pollutant degradation.

Sulfate radical-based advanced oxidation processes (SR-AOPs) are renowned for their exceptional capacity to degrade refractory organic pollutants due to their wide applicability, cost-effectiveness, and swift mineralization and oxidation rates. The primary sources of radicals in AOPs are persulfate (PS) and peroxymonosulfate (PMS) ions, sparking significant interest in their mechanistic and catalytic aspects. To develop a novel nanocatalyst for SR-AOPs, particularly for PMS activation, we synthesized carbon-coated FeCo nanoparticles (NPs) using solvothermal methods based on the polyol approach. Various synthesis conditions were investigated, and the NPs were thoroughly characterized regarding their structure, morphology, magnetic properties, and catalytic efficiency. The FeCo phase was primarily obtained at [OH-] / [Metal] = 26 and [Fe] / [Co] = 2 ratios. Moreover, as the [Fe]/[Co] ratio increased, the degree of xylose carbonization to form a carbon coating (hydrochar) on the NPs also increased. The NPs exhibited a spherical morphology with agglomerates of varying sizes. Vibrating-sample magnetometer analysis (VSM) indicated that a higher proportion of iron resulted in NPs with higher saturation magnetization (up to 167.8 emu g-1), attributed to a larger proportion of FeCo bcc phase in the nanocomposite. The best catalytic conditions for degrading 100ppm Rhodamine B (RhB) included 0.05g L-1 of NPs, 2mM PMS, pH 7.0, and a 20-min reaction at 25°C. Notably, singlet oxygen was the predominant specie formed in the experiments in the SR-AOP, followed by sulfate and hydroxyl radicals. The catalyst could be reused for up to five cycles, retaining over 98% RhB degradation, albeit with increased metal leaching. Even in the first use, dissolved Fe and Co concentrations were 0.8 ± 0.3 and 4.0 ± 0.5mg L-1, respectively. The FeCo catalyst proved to be effective in dye degradation and offers the potential for further refinement to minimize Co2+ leaching.

Eco-friendly synthesis of bimetallic FeCo nanocatalysts within heteroatom-doped carbon for oxygen reduction and zinc-air battery enhancement

Structural engineering emerges as a pivotal approach in crafting cost-effective and highly efficient catalysts for oxygen reduction reaction (ORR), emphasizing large surface areas, abundant reactive sites, and enhanced porosity. The incorporation of trace non-precious metals can significantly boost ORR performance through structural refinement. Here, we report on the synthesis of bimetallic FeCo nanoparticles embedded within a heteroatoms-doped carbon framework utilizing eco-friendly chitosan. This configuration yields a catalyst with marked activity for ORR in alkaline conditions, attributable to synergistic effects among Fe, Co, N, and O dopants. Comparative analysis reveals the superior performance of the FeCo-NC variant, characterized by a higher degree of defects and disorders. The standout FeCo-NC800W sample, with its 347.616 m2/g surface area and pyrolysis-induced graphene coating exhibits optimal ORR activity, closely adhering to a four-electron transfer pathway. Moreover, this catalyst demonstrates remarkable longevity and methanol resistance in ORR applications. FeCo-NC800W surpasses the conventional 20% Pt/C + RuO2 cathode in peak power density in a zinc-air battery setup, highlighting its potential as a high-performance, sustainable electrocatalyst.

A new magnetically separable zwitterionic copolymer hydrogel: Synthesis, characterization, and adsorption studies

In this study, a new magnetic organic–inorganic hydrogel composite was prepared and applied as an adsorbent for the removal of contaminants from aqueous media. The composite was prepared by loading FeCo nanoparticles on a zwitterionic copolymer hydrogel (poly(4-vinylbenzenesulfonate-co-[3-(methacryloylamino) propyl] trimethylammonium chloride), poly(MPTC-co-VBS)). Three composites with different FeCo contents were prepared to find the poly(MPTC-co-SVBS): FeCo ratio that achieves the highest adsorption of reactive yellow 160 (RY160) and Ni2+ ions. The prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffractometer (XRD), and vibrating-sample magnetometer (VSM).The characterization results revealed that the FeCo nanoparticles, poly(MPTC-co-SVBS) zwitterionic copolymer hydrogel, and FeCo-zwitterionic copolymer hydrogel composites were successfully prepared. The VSM and SEM analysis showed the ferromagnetic nature and porous structure of the FeCo-zwitterionic copolymer hydrogel composite. According to the XRD and FTIR, the FeCo was partially oxidized to CoFe2O4 during the preparation of the FeCo-zwitterionic copolymer hydrogel composite. The composite with the ratio of 2 wt% of poly(MPTC-co-SVBS) to 1 wt% of FeCo (2ZCPH-1FeCo) achieved the highest removal of both RY160 and Ni2+. The optimum removal of RY160 (92 %) was attained using 0.5 g/L of 2ZCPH-1FeCo at pH 7 after 60 min., while the optimum removal of Ni2+ (92 %) was attained using 1.0 g/L at pH 6.5 after 60 min. The PFO and PSO kinetic models described accurately the adsorption of RY160 and Ni2+,respectively. While the isotherm data of RY160 dye and Ni2+ was best described by Freundlich and Temkin models, respectively. Overall, the new FeCo-zwitterionic copolymer hydrogel composite demonstrated remarkable adsorption efficiency and simple magnetic separation post-treatment which makes it a prime contender for practical application in water treatment.

Highly porous layered carbon nanocomposites from the self-assembly of a poly(amic acid) for efficient oxygen reduction reaction catalysis

Porous layered carbon nanomaterials play important role in the efficient loading of electroactive substances for high performance energy conversion techniques. Herein, an intramolecular cyclization induced self-assembly (ICISA) strategy is proposed to prepare three-dimensional highly porous layered carbon nanostructures (LCs) for efficient loading of various transition metal nanoparticles for oxygen reduction reaction (ORR) catalysis. The amphiphilic alternating copolymer poly(amic acid) (PAA) is synthesized by the stepwise polymerization of hydrazine hydrate and pyromellitic dianhydride. Upon heating above 160 °C, the intramolecular cyclization reaction occurs, leading to the formation of rigid, crystalline and non-soluble polyimide segments in the backbone, which induces the self-assembly of the polymer to form dumbbell-shaped assemblies with a high solid content of 15%. After pyrolysis in a nitrogen atmosphere, LCs are obtained. Cobalt (Co), iron (Fe) and FeCo nanoparticles can be efficiently loaded, noted as Co@LCs, Fe@LCs and FeCo@LCs, respectively. The ORR catalytic performance of the catalysts is evaluated to give half wave potentials of 0.791, 0.787 and 0.812 V, and limit current densities of 4.92, 4.73 and 4.71 mA cm−2 for Co@LCs, Fe@LCs and FeCo@LCs, respectively. Overall, we propose an ICISA strategy to facilely prepare three-dimensional carbon nanomaterials with highly porous layered structure for efficient ORR catalysis.

Iron-Cobalt Nanoparticles Embedded in B,N-Doped Chitosan-Derived Porous Carbon Aerogel for Overall Water Splitting.

Given their intriguing properties, porous carbons have surfaced as promising electrocatalysts for various energy conversion reactions. This study presents a unique approach where iron-cobalt (FeCo) is confined in a boron, nitrogen-doped chitosan-derived porous carbon aerogel (BNPC-FeCo) to serve as an electrocatalyst for the hydrogen evolution and oxygen evolution reactions (HER and OER). The BNPC-FeCo-900 electrocatalyst demonstrates excellent catalyst activity, with very low overpotentials of 186 and 320 mV at 10 mA cm-2, low Tafel slopes of 82 and 55 mV dec-1, and low charge transfer resistance of 2.68 and 9.25 Ω for HER and OER, respectively. Density functional theory (DFT) calculations further reveal that the cooperation between the boron, nitrogen codoped porous carbon, and the FeCo nanoparticles reduces intermediates' energy barriers, significantly enhancing the HER and OER performance. In conclusion, this work offers significant and informative perspectives into the potential of porous carbon materials as dual-purpose electrocatalysts for water splitting.

FeCo/PANI composites as electromagnetic shields in the X-band: An understanding of the loss mechanisms

The growing dependence on electronic devices functioning within the microwave frequency range, coupled with the need for miniaturization, has resulted in increased instances of electromagnetic interference (EMI) in such devices. Besides altering device performance, the associated health hazards due to electromagnetic radiations have necessitated the urgency for developing efficient electromagnetic shielding materials. Here, highly magnetic FeCo nanoparticles, approximately 200 nm in diameter, have been used as magnetic filler materials in emeraldine base (PANI – EB) and emeraldine salt (PANI – ES) forms of polyaniline to understand the EMI shielding response in X-band frequency range (8.2–12.4 GHz). Composites using 10 % and 25 % FeCo by weight have been prepared using a physical mixing approach and uniform dispersion within the polymer matrix is ascertained using FE-SEM imaging and EDX elemental maps. Structural and magnetic properties of FeCo remain unaltered after the grind mixing process, as confirmed by XRD and VSM measurements. With the total shielding effectiveness remaining sufficiently low at 2–3 dB in FeCo/PANI – EB, significant enhancement to up to 40 dB is achieved in composites prepared in PANI – ES. Detailed investigations of electromagnetic parameters of the composites reveal the importance of the magnetic filler to achieve an absorption-dominated shielding of electromagnetic waves.

Fabrication of N and S co-doped lignin-based porous carbon aerogels loaded with FeCo alloys and their application to oxygen evolution and reduction reactions in Zn-air batteries

Zn-air batteries are a highly promising clean energy sustainable conversion technology, and the design of dual-function electrocatalysts with excellent activity and stability is crucial for their development. In this work, FeCo alloy loaded biomass-based N and S co-doped carbon aerogels (FeCo@NS-LCA) were fabricated from chitosan and lignosulfonate-metal chelates via liquid nitrogen pre-frozen synergistic high-temperature carbonization with application in electrocatalytic reactions. The abundant oxygen-containing functional groups on lignosulfonates have a chelating effect on metal ions, which can avoid the aggregation of metal nanoparticles during carbonation and catalysis, facilitating the construction of a nanoconfinement catalytic system with biomass carbon as the domain-limiting body and FeCo nanoparticles as the active sites. FeCo@NS-LCA exhibited catalytic activity (E1/2 = 0.87 V, JL = 5.7 mA cm−2) comparable to the commercial Pt/C in the oxygen reduction reaction (ORR), excellent resistance to methanol toxicity and stability. Meanwhile, the overpotential of oxygen evolution reaction (OER) was 324 mV, close to that of commercial RuO2 catalysts (351 mV). This study utilizes the coordination action of lignosulfonate to provide a novel and environmentally friendly method for the preparation of confined nano-catalysts and provides a new perspective for the high-value utilization of biomass resources.

In-situ exsolution of FeCo nanoparticles over perovskite oxides for efficient electrocatalytic nitrate reduction to ammonia via localized electrons

FeCo nanoparticles exsolved from Co-doped Sm0.9FeO3 nanofibers with abundant oxygen vacancies (Vos) are proposed as an efficient electrocatalyst to promote nitrate reduction reaction (NITRR). Such catalyst achieves a maximum Faradaic efficiency (FE) of 90.3 % and a large NH3 yield of 17.2 mg h−1 mg−1cat. at a negatively shifted potential of −0.9 V in 0.1 M PBS with 0.1 M NaNO3, and the alloy nanoparticles socketed into nanofibers remain extremely stable during long-term electrolysis. The reaction pathway favoring the formation of NH2OH is uncovered by in situ electrochemical tests and theoretical calculations reveal the exsolution of FeCo alloy combined with the generation of Vos enhances nitrate adsorption and lowers energy increase of the potential determining step. Finite-element simulations unveil the applied current and charges are localized on the alloys along the nanofiber, which confirms the exsolved FeCo nanoparticles are the main active sites for NITRR.

Surface engineering strategy to synthesize bicomponent carbons for rechargeable zinc-air batteries

Atomic Fe-Nx moieties and nanosized FeCo species anchored on carbons have each been demonstrated to be among the most effective active components for oxygen reduction and evolution reactions (ORR/OER), respectively in rechargeable zinc-air batteries (ZABs). However, incorporating both of these components in a single catalyst presents a great challenge due to the trade-off in formation between them during high-temperature preparation. Herein, we integrate them into a bicomponent carbon through a surface engineering strategy. In this process, K3[Fe(CN)6] is engineered on the surface of a precursor mixture consisting of polyaniline-coated graphene oxide and ZIF-67. This is followed by pyrolysis to produce the bicomponent carbon catalyst of FeCo nanoparticles modified carbon polyhedron (for accelerating the OER), supported on atomically dispersed Fe-N-doped carbon nanosheet (for boosting the ORR). The catalyst exhibits a small potential gap of 0.69 V for OER/ORR. In situ Raman spectroscopy demonstrates that spinel FeCo oxides may be responsible for OER. The use of this catalyst in ZABs achieves high power densities of 225 mW cm−2 in aqueous electrolyte and 164 mW cm−2 in solid-state electrolyte. Additionally, a small and stable voltage gap of 0.712 V at 10 mA cm−2 is maintained after 1035 discharge-charge cycles demonstrating the great application potential in energy devices.

Construction of 1D heterogeneous PPy@FeCo@PPy nanotubes with broadband and strong electromagnetic wave absorption

Developing nanomaterials with efficient electromagnetic wave absorption to eliminate increasingly serious electromagnetic pollution is of great significance. The peculiar electromagnetic characteristics of one-dimensional dielectric-magnetic heterostructures bring a promising strategy for designing high-efficiency absorber. Herein, a hierarchical PPy@FeCo@PPy nanotube was fabricated through a process of oxidative polymerization and electroless plating. In the product, the FeCo nanoparticles are encapsulate in the middle of the polypyrrole (PPy) dual conductive layers, which facilitates the deep construction of heterointerfaces and simultaneously prevents magnetic agglomeration. Furthermore, the hollow structure and suitable dielectric-magnetic component optimize impedance matching. Profiting from the reasonable structural design and the strong synergistic loss mechanism of dielectric-magnetic, the coaxial multi-shell PPy@FeCo@PPy nanotube exhibits prominent electromagnetic wave absorption performance, with a minimum reflection loss of −50.5 dB and the effective absorption bandwidth of 5.7 GHz at 2.0 mm. This work offers a gentle strategy for preparing ideal microwave absorbers by constructing dielectric-magnetic heterogeneous interfaces.

Recycling the spent cobalt-based perovskites for the high-active oxygen catalysts in zinc-air batteries

Cobalt (Co) is widely used in energy storage and conversion devices, although its content on our planet is not adequate. Therefore, recycling Co from the spent Co-enriched materials is indispensable. Co-based perovskites, which contain abundant Co, are extensively utilized in solid oxide fuel cells, three-way catalysts, and oxygen-permeable membranes, and the recovery of Co from the spent Co-based perovskites is necessary to meet the long-term requirement of Co. In this work, a facile and universal thermal reduction method (750 °C and N2 atmosphere) is employed to convert the spent cobalt-based perovskites into high-performance bifunctional oxygen catalysts for zinc-air batteries (ZABs), achieving high-efficient Co recovery and re-utilization. At high temperatures, melamine and dopamine hydrochloride are transformed into carbon nanotubes, C3N4 and reducing gases (such as NH3 and H2). Simultaneously, the metal elements in the spent Co-based perovskites (SrNb0.1Co0.7Fe0.2O3,SNCF) are converted into nano-scale alloy particles and metal nitrides. Then, the phase structures, micromorphology, and element valences of the obtained multiphase oxygen catalyst (SNCF–Ni-PM) are characterized by X-ray diffraction, scanning/transmission electron microscopy, and X-ray photoelectron spectroscopy, respectively. The electrochemical properties, including oxygen catalytic activities and stability, of SNCF-Ni-PM are measured by linear sweep voltammetry, chronopotentiometry, chronoamperometry, and cyclic voltammetry methods. Considering the practical applications, the aqueous and solid-state ZABs are assembled and measured. The results demonstrate that the multiphase SNCF-Ni-PM mainly includes carbon nanotubes, C3N4 nanosheets, and FeNiN or CoFe nanoparticles. Moreover, SNCF-Ni-PM exhibits excellent bifunctional oxygen catalytic activity, with an oxygen evolution reaction (OER) potential at 10 mA cm−2 of 1.51 V and an oxygen reduction reaction (ORR) half-wave potential of 0.77 V, outperforming most of the reported oxygen catalysts. Using SNCF-Ni-PM, the aqueous and solid-state ZABs can achieve high power densities of 295.9 and 228.4 mW cm−2, respectively, being superior to most ZABs. In addition, the aqueous ZAB with SNCF-Ni-PM can operate stably for 300 h with a slight degradation. This work provides a feasible method for effectively recycling Co from the spent Co-based perovskites.

Single-step generation of 1D FeCo nanostructures

Magnetic one-dimensional structures are attractive nanomaterials due to the variety of potential applications they can provide. The fabrication of bimetallic 1D structures further expands the capabilities of such structures by tailoring the magnetic properties. Here, a single-step template-free method is presented for the fabrication of 1D FeCo alloy nanochains. In this approach, charged single-crystalline FeCo nanoparticles are first generated by the co-ablation of pure Fe and Co electrodes under a carrier gas at ambient pressures and attracted to a substrate using an electric field. When reaching the surface, the particles are self-assembled into parallel nanochains along the direction of an applied magnetic field. The approach allows for monitoring the self-assembly particle by particle as they are arranged into linear 1D chains with an average length controlled by the deposited particle concentration. Magnetometry measurements revealed that arranging nanoparticles into nanochains results in a 100% increase in the remanent magnetization, indicating significant shape anisotropy. Furthermore, by combining x-ray microscopy and micromagnetic simulations, we have studied the local magnetization configuration along the nanochains. Our findings show that variations in magnetocrystalline anisotropy along the structure play a crucial role in the formation of magnetic domains.

Glu-Co-Assisted Iron-Based Metal–Organic Framework-Derived FeCo/N Co-Doped Carbon Material as Efficient Bifunctional Oxygen Electrocatalysts for Zn–Air Batteries

A Zn–air battery serves as an energy storage solution to address fossil energy and environmental concerns. However, sluggish kinetics in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) demand innovative, cost-effective, and stable bifunctional catalysts to replace precious metal catalysts. In this study, an FeCo-CNTs/KB catalyst was synthesized by pyrolyzing NH2-MIL-101(Fe) coated with glu-Co and conductive carbon (KB). This hierarchical structure comprises carbon nanotubes (CNTs) grafted onto a carbon matrix, housing abundant FeCo nanoparticles within the nanotubes or matrix. KB introduction enhances FeCo nanoparticle dispersion and fosters uniform CNT formation with smaller diameters, thus exposing active sites. Consequently, the FeCo-CNTs/KB catalyst exhibits remarkable bifunctional electrocatalytic activity: an ORR half-wave potential of 0.84 V and an OER overpotential of 0.45 V (10 mA cm−2). Furthermore, the FeCo-CNTs/KB catalyst in a secondary Zn–air battery showcases enduring charge–discharge performance (≥300 h).

Bimetallic FeCo nanoparticles embedded N-rich porous ZIF-derived carbon as highly active heterogeneous Fenton catalyst for degradation of tetracycline and organic dyes

Peroxymonosulfate (PMS) based advanced oxidation process (AOP) is used for the degradation of the organic molecules due to ease of reactive oxygen species (ROS) generation through activation. In this study, bimetallic FeCo nanoparticles (NPs) supported on N-doped porous carbons are prepared for the first time by in-situ co-precipitation of metal ions in ZIF-67 followed by carbonization. The prepared nanocomposite, denoted as Fe(x)Co@N-CZ-67, is used to activate PMS for Fenton-like degradations of tetracycline (TC) and dyes. The results reveal that about 96% of TC is degraded by Fe(0.4)Co@N-CZ-67 in 4 min. The catalyst can also degrade three organic dyes, namely methylene blue, neutral red and methyl orange with outstanding reaction rates of 1.75, 1.80 and 2.62 min−1, respectively. The excellent catalytic activities of the catalysts can be ascribed to the synergistic effects between Fe and Co that enhance the electron transfer rate, uniform dispersion of NPs, presence of N in support, and generation of surface PMS complexes with high oxidation activity. Based on the quench experiments, SO4•–, •OH, O2•− and 1O2 are determined to be the ROS responsible for degradations organic molecules. Fe(x)Co@N-CZ-67 shows excellent catalytic activity over ten consecutive cycles with negligible metal leaching and remarkable structural stability.