Fe Nanoparticles Research Articles

Synthesis and Characterization of Iron Nanoparticles from a Bioflocculant Produced by Pichia kudriavzevii Isolated from Kombucha Tea SCOBY

The intriguing characteristics of nanoparticles have fueled recent advancement in the field of nanotechnology. In the current study, a microbial-based bioflocculant made from the SCOBY of Kombucha tea broth was purified, profiled, and utilized to biosynthesize iron nanoparticles as a capping and reducing agent. UV–visible absorption spectroscopy, transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and TGA were used to characterize the Fe nanoparticles. The FT-IR spectra showed functional groups such as hydroxyl, a halogen (C-Br), and carbonyl, and the alkane (C-H) functional groups were present in both samples (bioflocculant and FeNPs) with the exception of the Fe-O bond, which represented the successful biosynthesis of FeNPs. The TEM investigation revealed that the sizes of the produced iron nanoparticles were between 2.6 and 6.2 nm. The UV-vis spectra revealed peaks at 230 nm for the bioflocculant and for the as-fabricated FeNPs, peaks were around 210, 265, and 330 nm, which confirms the formation of FeNPs. X-ray diffraction presented planes (012), (104), (110), (113), (024), (116), and (533) and these planes correspond to 17.17, 32.58, 33.75, 38.18, 45.31, 57.40, and 72.4° at 2Ө. The presence of Fe nanoparticles presented with 0.82 wt% from the EDX spectrum of the biosynthesized FeNPs. However, Fe content was not present from the bioflocculant. SEM images reported cumulus-like particles of the bioflocculant, while that of FeNPs were agglomerated and hexagonal with sizes between 18 and 50 nm. The TGA of FeNPs showed thermal stability by retaining above 60% of its weight at high temperatures. It can therefore be deduced that the purified bioflocculant produced by a yeast Pichia kudraivzevii can be utilized to synthesize FeNPs with the current simple and effective method.

Self-Adaptive Magnetic Liquid Metal Microrobots Capable of Crossing Biological Barriers and Wireless Neuromodulation.

Magnetic liquid-bodied microrobots (MRs) possess nearly infinite shape adaptivity. However, they currently confront the risk of structure instability/crushes during shape-morphing in tiny biological environments. This article reports that magnetic liquid metal (LM) MRs (LMMRs) show high structure stability and robust magnetic maneuverability. In this protocol, Fe nanoparticles are encapsulated inside less-than-10-μm LM microdroplets by establishing interfacial chemical potential barriers, yielding LMMRs. Their robust magnetic maneuverability originates from the magnetically controlled assembly of Fe nanoparticles inside LM and distinct liquid-solid interaction. With the self-adaptive shape-recovering capabilities even after 50% deformation, LMMRs can implement vertical climbing over walls up to 400% of its body length and traverse channels with the size of its two-thirds. The in vitro and in vivo experiments have both verified the effective magneto-mechanical stimulation of LMMRs upon neurons after their shape-adaptive crossing the blood-brain barrier under a driven magnetic field. Our work provides a promising strategy for wireless therapies with MRs by safely and effectively overcoming biological barriers.

Improved Thermoelectric Performance in n–type Bi2(Te,Se)3 Alloys through the Incorporation of Fe Nanoparticles

Improved Thermoelectric Performance in n–type Bi₂(Te,Se)₃ Alloys through the Incorporation of Fe Nanoparticles

Localized heating coupling with radical oxidation eliminating antibiotic resistance genes (ARGs) in interfacial photothermal Fenton-like disinfection process

Conventional oxidative disinfection processes are inefficient in eliminating intracellular antibiotic resistance genes (iARGs) due to the barrier of the cell membrane and the competitive reaction of cellular constituents within antibiotic-resistant bacteria (ARB), resulting in the widespread prevalence of ARGs in recycled water. This study presented the first application of localized heating coupling with advanced oxidation to destroy the resistant Escherichia coli cells and improved subsequent iARGs (blaTEM-1) degradation in a novel photothermal Fenton-like disinfection process. The Fe-Mn@CNT microfiltration membrane, comprising carbon nanotubes wrapped with Fe and Mn nanoparticles (Fe-Mn@CNT), was employed as a nanomaterial for photothermal conversion and H2O2 activation. The highly efficient absorption of full-spectrum photons by CNTs enabled the Fe-Mn@CNT membrane to concentrate light to generate localized intense heat, resulting in the destruction of ARB nearby, and the subsequent release of iARGs. Interfacial heat favored Fe-Mn-induced H2O2 activation, leading to the production of more ·OH, which in turn promoted the oxidation for ARG degradation and ARB cell damage. The results of the acetylcysteine quenching experiments indicated that interfacial heating and radical oxidation-induced accumulation of intracellular reactive oxygen species contributed to the elimination of about 1-log iARGs through direct attack. The integrity of the cell membrane, the morphology of ARB and the variation of i/e ARG copy numbers were observed to reveal that the introduction of interfacial heating aggravated the cell lysis and accelerated the iARGs release, resulting in the inactivation of 7.27-log ARB and the elimination of 4.64-log iARGs and 2.23-log eARGs. Localized heating coupling with ·OH oxidation achieved a 143 % increase in iARGs removal compared to the conventional Fenton-like oxidation. The interfacial photothermal Fenton-like disinfection process exhibited remarkable material stability, robust disinfection performance, and effective suppression of horizontal gene transfer, underscoring its immense potential to mitigate the risk of ARG dissemination in reclaimed water systems.

Leaching and vertical distribution of Fe and Zn citrate nanoparticles in Indian red soil

This research aims to address common constraints in the effective utilization of plant nutrients in soil, such as fixation, mobility, leaching, and reactions with soil colloids. To mitigate these issues, Fe and Zn citrate nanoparticles were synthesized and applied as nanochelators in a reconstructed soil profile column. We evaluated the mobility, release, and leaching behaviors of these nanoparticles. Results revealed that, no leaching of Fe and Zn citrate nanoparticles occurred even after a 90-day incubation. The release profiles exhibited a peak at 60 and 90 days for Fe and Zn respectively. In the mobility studies, Fe and Zn availability was highest in the 0–15 cm soil depth. Fe citrate and Zn citrate nanoparticles demonstrated the highest availability at 264.7 mg/kg and 86.26 mg/kg of soil, respectively as compared with commercial samples. The superior performance of Fe and Zn citrate nanoparticles was observed in terms of reduced leaching and improved accessibility, indicating their potential as efficient and environmentally-friendly plant nutrient sources. The study concludes that Fe and Zn citrate nanoparticles are stable nutrient sources that can enhance plant use efficiency with minimal environmental impact.

Atomically dispersed Fe-N4 sites in activation of peroxymonosulfate for wastewater purification: Mechanism of non-radical pathways and their quantification

Single-atom catalysts are promising alternatives to homogeneous and heterogeneous catalysts in the advanced oxidation processes for contaminant degradation; however, quantifying the exact contribution of nonradical reactive oxygen species has remained challenging. Herein, Fe single atoms anchored on nitrogen-doped carbonaceous substrates (Fe SAs-N-C) were synthesized for peroxymonosulfate (PMS) activation toward pollutant degradation. Fe SAs-N-C achieved high activity within 30 min, which is 17.20 and 5.08 times higher than those of N-C catalysts without or with Fe nanoparticles, respectively. A synergistic mechanism of singlet oxygen (1O2) and electron transfer for dominating pollutant degradation was revealed. The former contributed 78.50 % while the latter contributed 21.50 % in pollutant elimination. Density functional theory calculations uncovered that the O atom in −SO4 moiety of PMS was adsorbed on the Fe atoms, leading to the OH bond elongation and generating 1O2. While the absorbed O atom in OO bond near to −SO4 moiety of PMS tended to enlarge the OO bond and accelerate the electron transfer. The adsorbed PMS was prone to being decomposed into 1O2 due to a lower energy barrier (0.43 eV) of 1O2 rate-determining step than that of electron transfer (0.95 eV). Fe-N4 sites are both electron transfer channels and 1O2 formation sites. This work provides insights into the quantitative contributions of non-radical active species to pollutant degradation.

Microwaves in ferromagnetic composites Fe/Epoxy with aggregates of nanoparticles: Theory and experiment

Microwave transmission through plates of a composite material containing spherical Fe nanoparticles in an epoxyamine matrix and reflection from plates have been studied. Measurements were carried out at the frequencies from 26 to 32 GHz in the magnetic fields up to 12 kOe. The ferromagnetic resonance phenomenon in the composite has been investigated. The theory of electromagnetic waves transmitting through a composite material containing ferromagnetic particles, taking into account aggregating the particles, has been developed. A good agreement of calculation results and experimentally obtained field dependences of the transmission and reflection coefficients, as well as microwaves dissipation, has been achieved.

Ultrasmall Fe‐Nanoclusters‐Anchored Carbon Polyhedrons Interconnected with Carbon Nanotubes for High‐Performance Zinc‐Air Batteries

The catalytic activity of metal catalyst is closely related to its particle size. Yet, the size effect in electrocatalytic oxygen reduction reaction (ORR), an important reaction for metal‐air batteries and fuel cells, has not been clearly studied. Herein, a two‐step anchoring method is utilized to control the Fe catalyst in forms of nanoparticles (NPs), ultrasmall nanoclusters (NCTs), and isolated atoms as well as stabilized and dispersed by carbon polyhedrons interconnected with carbon nanotubes (CNTs). The uniformly distributed Fe NCTs displays superior ORR performance compared with Fe NPs, isolated Fe atoms, and commercial Pt/C. The brilliant ORR activity of Fe NCTs is a result of its unique electron structure and abundant edge and corner active sites. Due to the porous structure of carbon polyhedrons and high electron conductivity of CNTs, Fe NCTs also delivers an excellent discharge performance in zinc‐air battery with a peak power density of 213.3 mW cm−2 and long‐term stability. In these findings, a new strategy for the design of metal NCTs catalysts applied in various catalytic reactions is opened up.

Ni–Fe Nanoparticles Supported on UiO-66-X Catalyst for Hydrogenation of Fatty Acid Esters to Alcohols

Ni–Fe Nanoparticles Supported on UiO-66-X Catalyst for Hydrogenation of Fatty Acid Esters to Alcohols

Magnetic bimetallic nanoparticles confined growth for enhancement of electromagnetic loss in void@Fe@SiO2/Co/C particles

The dispersion of diverse magnetic metallic in a single particle plays an important role in microwave absorption; however, its contribution is not clear due to the challenge of controllable synthesis of magnetic bimetallic nanoparticles in one micro/nanostructure. Herein, a series of magnetic bimetallic nanoparticles separately confined growth in a hollow multi-shell microsphere with proper impedance matching characteristic were prepared, which can be used as theoretical models to elucidate magnetic coupling effect between diverse magnetic metallic nanoparticles in a single particle on electromagnetic attenuation. The coupling effect of magnetic Co and Fe nanoparticles dispersed in different shell effectively enhance the microwave absorption performance of void@Fe@SiO2/Co/C particles with minimum reflection loss (RLmin) of −62.3 dB (RL=-20 dB, 99 % absorption) at a thickness of 2.05 mm, provoking the maximum radar cross-section (RCS) reduction value of perfect electric conductor (PEC) 37.37 dBm2. Meanwhile, broad effective bandwidth (EBW, RL≤-10 dB, ≥90 % absorption) response of 7.04 GHz at a thickness of 2.44 mm was achieved. These findings can provide guidance for the designation of novel magnetic broadband microwave absorbing materials (MAMs).

Operando electron spin probes for the study of battery processes

Operando electron spin probes, namely magnetometry and electron paramagnetic resonance (EPR), provide real-time insights into the electrochemical processes occurring in battery materials and devices. In this work, we describe the design criteria and outline the development of operando magnetometry and EPR electrochemical cells. Notably, we show that a clamping mechanism, or springs, are needed to achieve sufficient compression of the battery stack and an electrochemical performance on par with that of a standard Swagelok-type cell. The tandem use of operando EPR and magnetometry allows us to identify five distinct and reversible redox processes taking place on charge and discharge of the intercalation-type LiNi0.5Mn0.5O2 Li-ion cathode. While redox processes in conversion-type electrodes are notoriously difficult to investigate using standard characterization methods (e.g. X-ray based) and/or post mortem analysis, due to the formation of poorly crystalline and metastable reaction intermediates and products during cycling, we show that operando magnetometry provides unique insight into the kinetics and reversibility of Fe nanoparticle formation in the Na3FeF6 electrode for Na-based batteries. Step increases in the cell magnetization upon extended cycling indicate the build-up of Fe nanoparticles in the system, hinting at only partially reversible charge–discharge processes. The broad applicability of the tools developed herein to a range of electrode chemistries and structures, from intercalation to conversion electrodes, and from crystalline to amorphous systems, makes them particularly promising for the development of electrochemical energy storage technologies and beyond.

Enhancement of oxygen flux through Nb-doped La0.4Sr0.6FeO3-δ ceramic hollow fiber membranes by Fe exsolution

In recent years, numerous studies have focused on the use of mixed ionic-electronic conducting oxides for coupled oxygen separation and catalytic reactions in membrane reactors. A promising strategy for the efficient fabrication of oxygen separation membranes involves modification of the membrane surface via exsolved metal nanoparticles decoration. Here, we present a detailed characterization of the structural and transport properties of a novel membrane material La0.4Sr0.6Fe0.95Nb0.05O3−δ (LSFNb5). The exsolution of Fe nanoparticles was observed after heating of LSFNb5 in a reducing atmosphere (5 % Н2/Ar) and was confirmed by X-ray diffraction analysis, Mössbauer spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The formation of Fe nanoparticles on the surface of LSFNb5 hollow fiber membrane in the reduction process leads to the enhancement of oxygen fluxes and reduces the apparent activation energy. Kinetic parameters for oxygen transport through LSFNb5 hollow fiber membrane estimated using two different models, are in good agreement with the experimental results. Furthermore, LSFNb5 hollow fiber membrane demonstrates stable performance both before and after surface treatment.

Nanoengineered pure Fe in a citrate matrix (Fe–CIT) with significant and tunable magnetic properties

This work demonstrates the synthesis and characterization of Fe nanoparticles surrounded by a citrate (CIT) matrix prepared at various temperatures and concentrations of metal, capping agent and reducing agent at standard conditions. We study the effect of reactant ratio and reaction temperature on the magnetization of the produced nanoparticles and their crystal structure. We found that for optimal metal concentrations, magnetic saturation increases with increase in the concentration of capping and reducing agents but decreases as the temperature of the reaction increases. Synthesis conditions were tailored to reveal nucleation of particles with average sizes ranging from 24 to 105 nm and a spherical shape. The ultra-high saturation magnetization of 228 emu g-1obtained for samples prepared at a metal precursor concentration of 27.8 mol l-1was attributed to the formation of small magnetic domains. Energy band gap measurements revealed a band gap energy for the Fe nanoparticles in the CIT matrix which is associated with CIT concentration and/or possible formation of a few thin layers of iron oxide shell and does not have a significant effect on the magnetic properties of the samples. Herein, we demonstrate that the synthesis parameters are crucial for the nucleation of Fe-CIT nanoparticles tailoring their magnetizatic properties as well as their potential for different applications.

Facile synthesis of graphitized carbon nanosheets from Chlorella with multiple Fe active sites to modify separator for efficient Li-S batteries

Li-S battery as an alternative to next-generation battery systems suffers from electrical insulating properties of sulfur, “shuttle effects” and slow kinetics of lithium polysulfides (LiPSs). Separator modification via catalysts with multiple scales of active sites are great potential; however, the preparation of such a kind of catalysts is still complex and tedious. Here, we developed a facile pyrolysis strategy to fabricate multiple Fe active sites on N-doped porous graphitized carbon nanosheets (Fe-NG) from Chlorella, including atomically dispersed Fe single atoms, Fe nanoclusters and carbon-coated Fe nanoparticles, which enhanced the affinity to LiPSs and accelerated their conversion kinetics. As Fe-NG was utilized to modify the separators, the resulting Li-S battery demonstrated an initial discharge capacity of 1062.1 mAh g−1 at 1 C and maintained at 678 mAh g−1 after 500 cycles with the average capacity decay rate of 0.072 % per cycle. This work provides a rational design and large-scale preparation routes for separator modifying catalysts with heterogeneous active species on biomass-derived carbons.

Iron nanoparticles enhance the efficiency of single-atom Fenton-like catalyst by boosting Fe-NX activity

Single-atom catalysts (SACs) have been widely employed for the removal of organic contaminants via advanced oxidation processes (AOPs). The underlying principle involves central metal atoms that interact synergistically with surrounding atoms in specific ensembles to adsorb reactants and facilitate catalytic reactions. However, comprehensive studies exploring the ensemble effect of SACs in combination with metal nanoparticles relatively rare. In this study, we have synthesized a highly active iron single-atom catalyst (Fe@BC), which features both Fe-Nx coordination sites and iron nanoparticles. Fe@BC exhibits remarkable adsorption and degradation capabilities for bisphenol A across a wide pH range from 3.0 to 11.0. Scavenging experiments coupled with electron paramagnetic resonance analysis have revealed that •OH and O2•− are the key reactive oxygen species within the Fe@BC/PAA system, with •OH playing a crucial role in the removal of bisphenol A (BPA). Our comprehensive characterization analysis has validated the simultaneous presence of Fe nanoparticles and Fe-Nx sites, which are crucial for the catalyst's high activity. Furthermore, our experimental data highlight the importance of the synergistic effect between these two components. Density Functional Theory calculations have provided additional insights, showing that the presence of iron nanoparticles significantly boosts the Fe-Nx sites' activity. This enhancement is achieved by increasing adsorption energy, promoting electron transfer to peracetic acid (PAA), and decreasing the energy barrier for the formation of active species. These findings are vital for the strategic refinement of Fe single-atom catalysts for PAA-based advanced oxidation processes.

EXOGENOUS APPLICATION OF IRON ANDZINC NANOPARTICLES ON GERMINATION AND GROWTH CHARACTERISTICS OF SUGARCANE (SACCHARUM OFFICINARUM L.) BUDNODE

The applications of nano-particles (NPs) in agriculture, such as nano-fertilizers, nano-insecticides, and nano-herbicides, are significantly impacted by their specific structure. In an experiment conducted at the College of Agriculture, University of Sargodha, the presence of Fe and Zn nano-particles at different concentrations was investigated to promote the appearance and growth of sugarcane buds. The experiment was conducted using a Randomize Complete Block Design (RCBD) method, with three replications of plant height at different concentrations of Fe NPs and Zn NPs. The results showed that high Zn concentrations, such as 75 and 100 mg L-1, significantly influenced germination-related characteristics, including minimum plant height. Sugarcane buds treated with Fe NPs at 50 mg L-1 and Zn NPs at 100 mg L-1 had the largest leaf area, while buds treated with Zn NPs at 50 mg L-1 had the minimum leaf-to-plant ratio. The topical application of Fe NPs and Zn NPs to sugarcane increased chlorophyll concentration and photosynthetic rate by 1.3 cm. The plant also showed the highest amount of zinc. At 100 mg L-1, the shoot Fe 6.9 concentration in Zn NPs was the highest. In conclusion, adding Zn and Fe nano-particles in amounts ranging from 100 mg L-1 to 50 mg L-1 significantly improved the growth and development of sugarcane bud nodes.

Synergistic effects of Fe single atoms and Fe nanoparticles modulating the electronic configuration for photocatalytic water treatment

Synergistic effects of Fe single atoms and Fe nanoparticles modulating the electronic configuration for photocatalytic water treatment

A multifunctional aspect of surface modification of cotton fabric with green synthesized titanium dioxide/iron nanocomposite using Psidium guajava leave extract

This study explores the use of green TiO2/Fe nanocomposite for surface modification of cotton fabric, aiming to minimize its limitations such as wrinkle, shrinkage, lower photocatalytic activity, microbial degradation, and poor durability. To prepare the nanocomposite, the iron (Fe) and titanium dioxide (TiO2) nanoparticles were first green synthesized using an extract of guava leaf (Psidium guajava) and mixed by using citric acid as a cross-linking agent. The modified cotton fabric was characterized by FTIR, TGA, DTG, SEM, and EDS. The FTIR spectra of the modified fabrics showed additional peaks at 483 cm−1 for Ti-O- and 1059 cm−1 for Fe-O-, indicating the incorporation of TiO2/Fe- nanoparticles which was also confirmed by SEM images. Fe nanoparticles enhanced TiO2 NPs’ photocatalytic activity, enhancing self-cleaning, UV resistance, stain resistance, anti-water absorption, and antibacterial activity in modified cotton fabric. Additionally, the wettability, thermal stability, mechanical and chemical stability of modified cotton fabric were also improved. As a result, the method of surface modification has great potential to improve the sustainability and usability of cotton fabric, supporting its wide range of uses in clothing, medical, and personal hygiene goods.

Tailoring structural and optical properties of Ti1-xMxO2 (M = Fe, Co, Ni, Cu, and Zn) nanoparticles for enhanced antimicrobial activity: a sol-gel synthesis study

Titanium dioxide (TiO2) nanoparticles possess intriguing properties and have been extensively utilized in medical applications due to their exceptional antimicrobial characteristics. The antimicrobial efficacy can be heightened by altering the structural morphology, size, and optical properties through the introduction of transition metal ions (M: Fe, Co, Ni, Cu, and Zn) with a concentration of x = 0.02 into TiO2, thereby producing Ti1 -xMxO2 powder via the sol-gel method at a sintering temperature ranging from 500 °C to 600 °C. The morphological characteristics of Ti1 - xMxO2 were analyzed using FT-IR, UV-DRS, XRD, TGA, BET, and SEM-EDAX techniques. Substituting M-doped TiO2 at a sintering temperature of 500 °C results in all doping ions yielding the Ti1 -xMxO2 anatase phase. Conversely, at 600 °C, the doping ions M: Cu, Co, Zn exhibit a tendency to substitute the TiO2 structure, destabilizing the anatase phase and leading to the formation of an anatase-rutile dual phase with larger crystal size. At elevated temperatures, ions with larger radii than Ti (0.61), namely Cu (0.73), Co (0.75), and Zn (0.74), tend to be substituted, thereby altering the structure of TiO2. The antimicrobial efficacy, evaluated based on the inhibition zone, demonstrates that Ti1 -xMxO2 effectively inhibits the cellular activity of Salmonella typhimurium (Gram -) and Staphylococcus aureus (Gram +) bacteria compared to TiO2.

Based on size-exclusion effect of selective removal of organic pollutants in complex water quality by low temperature plasma: Degradation behavior and selective mechanism analysis

The presence of natural organic matters (NOMs) will have a negative effect on the removal of small molecule organic contaminants in complex water quality, therefore, it’s very important to design a catalyst with size-exclusion function to achieve the selective removal of targeted pollutant. Herein, a novel ZIF-L catalyst precursor with lamellar stack structure is designed, and iron as heteroatom is doped in ZIF-L gaps named ZIF-L@Fe. After pyrolysis, Fe ions are transformed into Fe nanoparticles, and act as the active sites of catalyst. In order to verify the selective removal ability of resulted NSC@Fe in dielectric barrier discharge (DBD), tetracycline hydrochloride (TTCH) and humic acid (HA) is selected as the target pollutant and coexistence macromolecular interferent, respectively. In the presence of HA (50 mg/L), the degradation rate of TTCH in the system is not significantly affected (with HA, k = 0.037 min−1; without HA, k 0.036 min−1), which is mainly due to the layered material stacking characteristics (size-exclusion). The degradation mechanism and pathway are further confirmed by radical quenching experiments and liquid chromatography−mass spectrograph (LC−MS), respectively. This study is believed to shed new light on how to rationally design catalyst with selective removal of organic pollutants in complex water quality for water remediation.