α-Fe2O3 Nanoparticles Research Articles

Synthesis of Xanthan Gum Anchored α-Fe2O3 Bionanocomposite Material for Remediation of Pb (II) Contaminated Aquatic System.

Increases in community and industrial activities have led to disturbances of the environmental balance and the contamination of water systems through the introduction of organic and inorganic pollutants. Among the various inorganic pollutants, Pb (II) is one of the heavy metals possessing non-biodegradable and the most toxic characteristics towards human health and the environment. The present study is focussed on the synthesis of efficient and eco-friendly adsorbent material that can remove Pb (II) from wastewater. A green functional nanocomposite material based on the immobilization of α-Fe2O3 nanoparticles with xanthan gum (XG) biopolymer has been synthesized in this study to be applied as an adsorbent (XGFO) for sequestration of Pb (II). Spectroscopic techniques such as scanning electron microscopy with energy dispersive X-ray (SEM-EDX), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet visible (UV-Vis) and X-ray photoelectron spectroscopy (XPS) were adopted for characterizing the solid powder material. The synthesized material was found to be rich in key functional groups such as -COOH and -OH playing important roles in binding the adsorbate particles through ligand-to-metal charge transfer (LMCT). Based on the preliminary results, adsorption experiments were conducted, and the data obtained were applied to four different adsorption isotherm models, viz the Langmuir, Temkin, Freundlich and D-R models. Based on the high values of R2 and low values of χ2, the Langmuir isotherm model was found to be the best model for simulation of data for Pb (II) adsorption by XGFO. The value of maximum monolayer adsorption capacity (Qm) was found to be 117.45 mg g-1 at 303 K, 126.23 mg g-1 at 313 K, 145.12 mg g-1 at 323 K and 191.27 mg g-1 at 323 K. The kinetics of the adsorption process of Pb (II) by XGFO was best defined by the pseudo-second-order model. The thermodynamic aspect of the reaction suggested that the reaction is endothermic and spontaneous. The outcomes proved that XGFO can be utilized as an efficient adsorbent material for the treatment of contaminated wastewater.

Structural characterization of cuboidal α-Fe2O3 nanoparticles synthesized by a facile approach

α-Fe2O3 nanoparticles were synthesized using Tabebuia aurea leaf extract by a facile approach. The signature peaks for Fe and O in the EDX spectrum verified the formation of Fe2O3 nanoparticles. Cuboidal-shaped nanoparticles were observed in the FE-SEM image. In the XRD pattern, it was observed that the peaks belong to α-Fe2O3 nanoparticles. These particles were pure and crystalline with an average particle size of 25.69 nm. The signals at 538 and 494 cm−1 in the FTIR image confirmed the formation of hematite nanoparticles. BET analysis showed a comparatively greater surface area (31.03 m2/g) than the commercial α-Fe2O3 nanoparticles, and the pores were mesoporous. XPS analysis confirmed the existence of α-Fe2O3 by showing the specific oxidation states for iron and oxygen at 710.34 and 529.67 eV, respectively. The saturation magnetization value of 13.97 emu/g confirmed the superparamagnetic nature. The TGA, which determined the thermal stability of the nanoparticles, reported a total weight loss of 12.75%. Hence, the highly crystalline, pure, mesoporous, superparamagnetic α-Fe2O3 nanoparticles with high surface area synthesized using T. aurea leaf extract can be potentially applied in diverse fields.

乾式機械的処理を利用した無溶媒均一沈殿法によるヘマタイトナノ粒子の合成

Hematite (α-Fe2O3) nanoparticles were synthesized by a solvent-free homogeneous precipitation method using urea hydrolysis via dry mechanical treatment of urea and ferric nitrate nonahydrate for activation. This novel method consists of high-energy ball milling of the raw materials and subsequent heating of the activated liquid precursor, which can provide smaller-sized nanoparticles than conventional methods. The milling and heating conditions were systematically investigated in detail. It was found that the hematite formation can be promoted by milling ferric nitrate nonahydrate and urea simultaneously under dry conditions even when relatively gentle milling and heating treatments were employed. The hematite nanoparticles had a similar crystallite size and particle diameter regardless of the conditions. This method can contribute to large-scale environmentally-friendly synthesis of fine hematite nanoparticles.

Clay-derived Synthesis of Supported α-Fe2O3 Nanoparticles: Shape, Adsorption, and Photo-catalysis

Background: This paper reports a versatile bentonite clay-mediated growth method for selectively synthesizing zero-dimensional α-Fe2O3 nanoparticles and one-dimensional α-Fe2O3 nanorods. Method: In such a growth process without any other surfactant or additive, the bentonite clay is not only used as the supporter, but also as a shape mediator for α-Fe2O3 nanocrystals. The products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results: The as-prepared products were used to investigate their promising adsorptive and photocatalytic applications in water treatment. According to the Langmuir equation, the maximum adsorption capacity of the α-Fe2O3/bentonite composite for Congo red (CR) is calculated to be 96.9 mg·g-1. Furthermore, the α-Fe2O3/bentonite nanocomposites also show an excellent photocatalytic property in the degradation of methyl orange (MO). Conclusion: This facile and novel synthesis method has the potential to be applied to prepare the low-cost α-Fe2O3/bentonite nanocomposite for the removal of CR and MO.

Photodegradation of methyl orange dye by using Azadirachta indica and chemically mediated synthesized cobalt doped α-Fe2O3 NPs through co-precipitation method

In current study, the Co-precipitation method was successfully used for the synthesis of Cobalt (Co) doped hematite (α-Fe2O3) nanoparticles (NPs). The synthesized Co-doped α-Fe2O3 NPs were analyzed by various characterization techniques. The chemical and greenly synthesizedα-Fe2O3 NPs had an average crystallite size of 22.63 and 16.02 nm as analyzed by XRD respectively. The Raman peaks marks the crystalline nature and hematite phase of Fe2O3 nanoparticles. The spherical shape of the Co-doped α-Fe2O3 NPs in both chemical and green methods is determined by the SEM pictures. UV–visible absorption studies marked the values of band gap i.e. 2.28 and 2.61 eV for chemical and green synthesized Co-doped α-Fe2O3 respectively. By employing the use of methyl orange dye, the photocatalytic action of α-Fe2O3 NPs was analyzed. The findings have shown that an appropriate amount of Co-dopant can significantly lead into an increase in the number of hydroxyl radicals produced from α-Fe2O3 NPs. They cause increase the methyl orange dye degradation rate. The results have shown that Azadirachta indica extract has the potential to produce α-Fe2O3-NPs in an environmentally safe manner. This research concluded that the α-Fe2O3 NPs have better photocatalytic potential with aqueous Azadirachta indica leaves extract.

Electrochemical and sensing properties of α-Fe2O3 nanoparticles synthesized using hydrothermal method at low reaction temperature

Electrochemical and sensing properties of α-Fe2O3 nanoparticles synthesized using hydrothermal method at low reaction temperature

Nitrate adsorption using green iron oxide nanoparticles synthesized by Eucalyptus leaf extracts: Kinetics and effects of pH, KCl salt, and anions competition

This research investigated the colloidal stability and reactivity of green iron oxide nanoparticles for removing NO3– ions from polluted water. These nanoparticles were synthesized by Eucalyptus globulus leaf extract (EL-Fe NPs). Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and dynamic light scattering (DLS) were utilized to characterize EL-Fe NPs. The effect of contact time, different pH, KCl salt, and anions (PO43−, SO42−, HCO3–, Cl−), on NO3– adsorption using EL-Fe NPs were evaluated. Based on the results, Fe3O4 and α-Fe2O3 nanoparticles were encapsulated by polyphenols and have irregular nano-particulate structures. After 30 min, the maximum adsorption capacity of 1.5 g L−1 EL-Fe NPs dispersed in 50 mg L−1 NO3– solution with a pH of 3.7 was acquired at about 12.91 mg/g. Adsorption of NO3– on EL-Fe NPs was strongly pH dependent, and at pH > 6.6 no significant adsorption occurred. KCl salt by agglomeration of EL-Fe NPs, the mean particle size varied between 25.6 nm and 63 nm, and NO3– adsorption decreased dramatically. It was observed that EL-Fe NPs significant affinity to adsorb PO43− ions. As a result, no significant adsorption of NO3– ions onto EL-Fe NPs was detected in the presence of phosphate ions. The experimental data were reasonably fit to a pseudo-second-order kinetic model (R2 = 0.992), which can be concluded that the primary mechanism of NO3– adsorption is electrostatic. This work indicated that the removal of NO3– using EL-Fe NPs was influenced by the type and concentration of accompanying cations and anions.

Görünür-Işık ile Çalışan Fotokatalizör Hematitin Çinko ve Bakır ile Katkılanmasıyla Geliştirilmesinin Karşılaştırmalı İncelenmesi

The low cost, earth abundance, nontoxic, and efficient photocatalysts materials have a critical role in order to solve environmental issues. In this regard, hematite (α-Fe2O3) has received significant attention due to its desirable properties. In the present study, zinc-doped and copper-doped hematite nanoparticles were synthesized by the hydrothermal method. The photocatalytic features of produced nanopowders were investigated. The evaluations of photocatalytic activities of synthesized nanoparticles were executed by monitoring the degradation rate of Rhodamine B (RhB) under the solar simulator in heterogeneous photocatalysis. Compared to commercial Degussa TiO2 powder, the transition metal doped hematite (α-Fe2O3) samples showed better photocatalytic activities against RhB under the solar simulator. It was observed that even though there were no significant differences in their characteristic properties strongly affecting photocatalytic activity such as morphological features, optical absorption characteristics, and band gaps, Cu-doped α-Fe2O3 nanoparticles exhibited higher photocatalytic activity, which is %20 higher than the Zn-doped α-Fe2O3. The synthesized Cu-doped hematite nanoparticles are hopeful materials as a visible-light-driven photocatalytic material to degrade organic pollutants in aquatic media.

Uniform Formation of a Characteristic Nanocomposite Structure of Biogenous Iron Oxide for High Rate Performance as the Anode of Lithium-Ion Batteries

Recently, Fe2O3 has been considered as an alternative anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity (approximately 1000 mA h g–1), low cost, and nontoxicity. However, its rate performance remains poor relative to that of the conventional graphite anode. In this study, Fe2O3-based anodes were prepared through the annealing of biogenous Fe2O3 (L-BIOX) samples produced by an aquatic Fe-oxidizing bacterium. The effect of the annealing temperature on the performance of the synthesized Fe2O3-based material as the anode of an LIB was investigated. Electrochemical measurements revealed that the annealed L-BIOX samples at 300–700 °C exhibited higher rate performances than the unannealed material. Particularly, the sample annealed at 700 °C exhibited the highest capacity among the synthesized materials and showed a higher performance than the previously reported Fe2O3-based anodes. It exhibited a capacity of 923 mA h g–1 even at a high current density of 2 A g–1. After annealing at 700 °C and discharging, the synthesized biogenous material had a uniform nanocomposite structure composed of α-Fe2O3 nanoparticles dispersed in an amorphous matrix of Li–Si–P oxide. To form this uniform nanostructure, the solid-state diffusion resistance of the Li+ ions in the active material was reduced, which consequently improved the rate performance of the electrode. Therefore, this study provides substantial insights into the development and improvement of the performance of novel Fe2O3-based nanomaterials as the anode of LIBs.

BiVO4 charge transfer control by a water-insoluble iron complex for solar water oxidation

Photoelectrochemical water splitting can become efficient by grafting co-catalysts on semiconductors that improve the interfacial oxygen evolution reaction. We applied a simple non-noble metal pre-catalyst, [FeII(PBI)3]2+ (PBI is 2-(2′-pyridyl)benzimidazole ligand) for this purpose on a nanopyramidal BiVO4 semiconductor that was morphologically optimal for efficient light harvesting, but its performance suffered from V-poor surface recombination sites. The [FeII(PBI)3]2+in situ transformed to α-Fe2O3 nanoparticles on V-vacant areas of BiVO4 mending their photocurrent-limiting effect. Photoelectrochemistry at pH 8.2 confirmed that the α-Fe2O3 co-catalyst improved the charge transfer efficiency by an order of magnitude, suppressed the recombination in the bulk and reduced the charge transfer resistance. Overall, the α-Fe2O3 suppressed the recombination on the V-poor surface, while at high potentials it provided high-valent centers for the oxygen evolution. The resulting photocurrent density far exceeding that of BiVO4 or samples modified by FeCl3 or Fe(NO3)3 underlines the metallochaperone-like effect of the PBI ligand.

Structural, optical and magnetic properties of chitosan mediated α-Fe2O3 nanoparticles

The environmentally-safe, copious, inexpensive, non-toxic and thermally stable α-Fe2O3 (Hematite) nanoparticles attracted more attention in the recent times. In the present work, we have made an attempt to develop α-Fe2O3 nanoparticles using chitosan (a naturally available biodegradable polymer) as a medium and iron nitrate as precursors. The chitosan gel is first prepared and then solubilized under pressure in water using CO2. Herein, we study the effects of the aqueous chitosan medium on the properties of α-Fe2O3 in terms of size, shape, crystallinity, optical, and magnetic properties. The developed nanoparticles have been characterized for their structural, morphological, thermal, magnetic, and optical properties using XRD, Raman Spectroscopy, HR-TEM, Thermogravimetric analysis, Vibrating sample magnetometer, FTIR, and UV–visible spectroscopy techniques. All the studies confirm the formation of hexagonal crystal structure with a space group R -3 c with polygonal shaped nanoparticles with size ranging from 10 to 30 nm. UV–Visible Spectroscopy shows a standard band gap of 3.34 eV, which is surprisingly much higher in comparison to the existing reports. Magnetic properties reveal the presence of antiferromagnetic nature at room temperature coupled with a ferromagnetic/superparamagnetic behavior.

Development of ceramic grade red iron oxide pigment from waste iron source

Ceramic grade red iron oxide (α-Fe2O3) nanoparticles pigments have been synthesized from waste condensed milk containers which contain a prominent amount of iron (93.2%). The synthesis method comprised of two steps: in the first step ferrous sulfate was prepared following an acid leaching method; while the second step was oxidation and calcination of ferrous sulfate to produce desired α-Fe2O3 in nano form. The structure, functional groups, chemical state, morphology, particle size, surface area, elemental, thermal analysis and magnetic properties of the samples were investigated using XRD, FTIR, XPS, SEM, BET, EDS, TG-DT and VSM respectively. Pure hematite (α-Fe2O3) phase was confirmed by XRD and the average crystal sizes were in the range 34–126 nm have been performed by Debye-Scherer's formula, which are consistent with the results as achieved from SEM images. Agglomerated irregular spherical nanoparticles (45–149 nm) were found in SEM image. The surface chemistry and the chemical state (Fe3+) of the hematite nanoparticles was also confirmed by XPS. The mesoporous nature of the nanoparticles with high surface area were measured by BET and it has been revealed that the BET specific surface area (33.55 m2/g) was marginally higher than the commercial one. The magnetic nature of the nanoparticles was portrayed by VSM and the nanoparticles showed the ferromagnetic behavior. Moreover, particle size distributions and zeta potential values have been also measured by DLS.

Synthesis and characterization of nano-hematite

In this work, synthesis of α-Fe2O3 via co-precipitation method is reported. Further, their detailed characterizations of structural properties, surface morphology, thermal and optical properties using X-ray diffraction (XRD), Raman Spectroscopy, Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FT-IR), High resolution transmission emission microscopy (HR-TEM), and UV–Visible spectroscopy techniques were performed. All the studies reveal the successful synthesis of α-Fe2O3 nanoparticles with a polygon-shaped morphology and with an average particle size around 10–25 nm. It also confirmed the development of hexagonal crystal structure with a space group R-3c. The obtained nano powders imparted intense red pigmentation, hence proving its applications in the pigment industry. UV–Visible Spectroscopy showed a standard band-gap of 1.8 eV, which is unexpectedly much smaller in comparison to the prevailing reports. Thus, the synthesis of α-Fe2O3 nanoparticles with co-precipitation method is promising for band-gap narrowing of the iron oxide systems.

Hydrothermal synthesis of α-FeOOH (1D) nanorods and their transition to α-Fe2O3 (0D): an efficient photocatalyst in neutralizing hazardous organic dyes

α-FeOOH nanorods transitioned to α-Fe2O3 nanoparticles at 520 °C. Both act as photocatalysts, degrading BG and RhB with 96% (110 min) and 93% (90 min) for α-FeOOH and 99% (100 min) and 99.4% (80 min) for α-Fe2O3.

Rapid detection of gingerol and thymol in medicinal foods based on Fe2O3 nanoparticles modified glassy carbon electrode

Ginger and Ajwain are used extensively in food products, natural medicine to treat certain common diseases and as an immunity booster against viral infections. In this work, we report the fabrication of a novel electrochemical sensor based on α-Fe2O3 nanoparticles for detection and quantification of [6]-Gingerol (GIN) and Thymol (THY) which are water soluble phytochemicals derived from edible herbs Ginger and Ajwain respectively. The α-Fe2O3 nanoparticles were synthesised by sol-gel method and its structure and composition were confirmed by powder X-ray diffraction and photoelectron spectroscopy studies. The α-Fe2O3 NPs modified glassy carbon electrode (GCE) exhibited an excellent electrocatalytic activity towards the oxidation of GIN and THY in phosphate buffer saline at pH 7. The α-Fe2O3 modified GCE exhibited the lowest detection limits of 35.2 nM and 24 nM for GIN and THY respectively over the corresponding dynamic ranges of 55.6 nM to 118 µM and 27.8 nM to 56 µM. Detailed interference study confirmed the potential anti-interference ability of the fabricated sensor against a number of potential interfering compounds. Cyclic stability study yielded relative standard deviation (RSD) values of 9.9% and 9.18% for GIN and THY respectively, demonstrating excellent stability of the sensor. Reproducibility of the α-Fe2O3/GCE was investigated by testing a number of electrodes which yielded RSD values of 1.08% and 0.97%, for GIN and THY respectively. These promising characteristic features of the proposed sensor make it suitable for quick and precise detection of GIN and THY in food and natural medicines.Graphical Abstract

Green Synthesis of Α-Fe2O3 from Ginger Extract Enhanced the Potential Antioxidant Activity Against DPPH

Synthesis of nano-oxides in an easy and environmentally friendly way using simple and green materials is one of the hot interests of sustainable chemistry for lots of pharmaceutical and medical applications. Herein, we synthesized α-Fe2O3 nanoparticles (α-Fe2O3 NPs) using ginger extract after that calcination at 400 C° for 4 h. The prepared α-Fe2O3 nanoparticles were examined using ultraviolet-visible reflection spectroscopy (UV-VIS), Fourier Transform Infrared Spectroscopy (FTIR), photoluminescence spectroscopy (PL), X-ray diffraction (XRD), field emission scanning microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, and zeta potential. After well characterizations, the potency of the prepared α-Fe2O3 nanoparticles to monitor some scavenging activity was explored against DPPH. Results revealed that PL intensity has one peak in the UV region between (480-490) nm of the spectrum depending on the geometric shape and size of the α-Fe2O3 NPS. The UV-visible spectra showed a peak at 296.0 nm, which represented the α-Fe2O3 NPs. The EDX micrograph confirmed pure oxide and the XRD pattern showed that the α-Fe2O3 NPs had an average crystal size (19.3) nm. SEM images of α-Fe2O3 NPs revealed spherical, rod, and irregular shapes and sizes ranging from (15 to 60) nm. Moreover, the antioxidant activity of α-Fe2O3 NPs against DPPH showed 51.8% free radical scavenging ability at 360 μg/mL, which approved good evidence of the antioxidant activity of α-Fe2O3 NPs.

Investigation of Biofabricated Iron Oxide Nanoparticles for Antimicrobial and Anticancer Efficiencies

Capparis zeylanica leaf extract was employed in this work to create iron oxide nanoparticles (α-Fe2O3) using anhydrous ferric chloride. The UV spectrum, XRD, FT-IR, and FE-SEM with EDX methods were used to characterize the fabricated nanoparticles. The iron oxide nanoparticles obtained were spherical in form, with an average crystallite size of 28.17 nm determined by XRD. The agar well diffusion method was used to assess the antimicrobial activity of the α-Fe2O3 nanoparticles created in this study against pathogenic organisms, Gram-negative bacteria (Escherichia coli and Pseudomonas aeroginosa), Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes), and fungi (Candida albicans and Aspergillus niger). Among the pathogens tested, S. pyogenes had the highest zones of inhibition (25 ± 1.26 mm), followed by S. aureus (23 ± 0.8 mm), E. coli (23 ± 2.46 mm), P. aeroginosa (22 ± 1.86 mm), C. albicans (19 ± 2.34 mm) and A. niger (17 ± 3.2 mm). The substance was further tested for anticancer activity against A549 (lung cancer) cells using the MTT assay. The cytotoxic reaction was found to be concentration-dependent. The present study, therefore, came to the conclusion that the bio-effectiveness of the manufactured α-Fe2O3 nanoparticles may result in applications in biomedical domains.

Effective Attenuation of Electromagnetic Waves by Synergetic Effect of α-Fe2O3 and MWCNT/Graphene in LDPE-Based Composites for EMI Applications.

In this study, a polymer nanocomposite is synthesized using magnetic and conducting fillers for enhanced electromagnetic interference (EMI) shielding. Alfa-ferrite (α-Fe2O3) nanoparticles with minimal multiwalled carbon nanotube (MWCNT) as low as 5 weight % in combination with variable concentrations of graphene nanoplatelets (GNP) are used as fillers in low-density polyethylene (LDPE) polymer matrix. Nanofillers and the polymer matrix are characterized by various techniques such as XRD, SEM, color mapping, EDAX, TGA, etc. The EMI shielding efficiency of the LDPE-based nanocomposites is tested using Vector Network Analyzer (VNA). The results showed that composite with LDPE:MWCNT:GNP:α-FO-50:5:40:5 displayed enhanced EMI shielding (in X-band (8.2-12.4 GHz) compared to other concentrations studied. This is due to the superior ohmic, dielectric, and magnetic losses at this particular composition and to the synergism amongst the filler. An attenuation of 99.99% was achieved for 5% α-Fe2O3. The mechanistic aspects of the shielding are discussed using permittivity, conductivity, and attenuation.

Exploration of Fe speciation preference for aerobic methane oxidation by using isotopic Fe-modified zeolites

Methane-oxidizing bacteria (MOB) dominate the natural consumption of fugitive methane (CH4), which is largely produced by methanogens in aerobic-anaerobic habitats. Although the influence of iron (Fe) on MOB activities has been examined, the underlying mechanism in terms of the preference remains to be clarified, the key to which may be the extracellular uptake of Fe during CH4 oxidation. In this study, isotopic ferric chloride was used to treat stable raw zeolites (Fe-Z) through a pyrolytic procedure (Fe-Z600). All samples were allowed to develop for 52 d, and the CH4 oxidation rate and contents of Fe and extracellular polymers (EPS) in different MOB periods were determined. The cumulative oxidation mass of CH4 in Fe-Z600 was two times that in Fe-Z, and the abundance of Methylocystis in Fe-Z600 was 21% higher. More uniformly dispersed α-Fe2O3 nanoparticles were formed during the pyrolysis of Fe-Z600, which accelerated the extracellular migration and stimulated MOB growth. In addition, Fe-Z600 presented the strongest extracellular polysaccharides (ECPs) inhibition; the total amount of ECPs was about 53.9% lower than that of the Raw group. Simultaneously, Fe was more likely to be stored in loosely bound EPS (LB-EPS), with a maximum cumulative amount of 38% during the stable period of CH4 oxidation in Fe-Z600, decreasing LB-EPS and tightly bound EPS by 47.4% and 75.4%, respectively. The presented findings can provide guidance for alleviating EPS blockage in long-term activities of MOB to ensure their efficient and durable CH4 oxidation.

Preparation and thermogenic performance of monodisperse ferromagnetic Fe/SiO2 nanoparticles for magnetic hyperthermia and thermal ablation*

Ferromagnetic nanoparticles have great potential to be used in the field of magnetic hyperthermia and thermal ablation due to its high saturation magnetization (Ms) and high heating efficiency. In this paper, monodisperse spherical α-Fe2O3 nanoparticles were prepared by hydrothermal method using FeCl3, NaHCO3 and Na2SO4 as reactants. Then monodisperse Fe/SiO2 nanoparticles with core/shell structure were obtained by coating SiO2 on the surface of α-Fe2O3 nanoparticles and reducing at 500℃ in hydrogen atmosphere. The diameter of Fe core is about 230 nm and the thickness of SiO2 coating is about 75 nm. Magnetic measurements show that Fe/SiO2 nanoparticles exhibit typical ferromagnetic properties with Ms about 132.5 emu/g at 25 ℃. As-obtained Fe/SiO2 nanoparticles have higher heating efficiency than superparamagnetic ferrite nanoparticles. The high heating ability of the Fe/SiO2 nanoparticles is estimated to be related to the hysteresis loss and Brownian relaxation mechanism during alternating magnetization. The results show that Fe/SiO2 nanoparticles are promising for the applications of magnetic hyperthermia and thermal ablation.