Bioinspired Polydopamine Modification for Interface Compatibility of PDMS-Based Responsive Structurally Colored Textiles.

Textiles that can repeatedly change color in the presence of external stimuli have attracted great interest. Effectively designing to produce such functional textiles is essential, yet there remain challenges like producing stable coloration, rapid response, and reverse color changing. Here, the preparation of a magnetic field response (MFR) textile with a fast magnetic field response, brilliant structural coloration, and mechanical robustness is reported. The MFR textile is knitted by incorporating magnetic particles' ethylene glycol (EG) suspension within polydimethylsiloxane (PDMS)-based fibers. A surface modification strategy is designed to prevent EG from seeping out along the PDMS polymer chains. A PDMS fiber is encapsulated in waterborne polyurethane, and a polydopamine joint layer is used. The MFR textile demonstrates magnetic field-triggered structural colors, and the breaking strength and elongation at break of each composite fiber are improved. In addition, multishaped patterns can be printed on the MFR textile with the help of the photo etching technology, which enhances the applications of the new functional textiles.

Magnetite encapsulated in carbon shell particles (Fe3O4@C) to boost anaerobic methanogenesis of chloramphenicol wastewater.

Magnetite (Fe3O4) is extensively applied to enhance efficacy of anaerobic biological treatment systems designed for refractory wastewater. However, the interaction between magnetite, organic pollutants and microorganisms in digestion solution is constrained by magnetic attraction. To overcome this limitation and prevent magnetite aggregation, the core-shell composite materials with carbon outer layer enveloping magnetite core particles (Fe3O4@C) were developed. The impact of Fe3O4@C with varying Fe3O4 mass ratios on the anaerobic methanogenesis capability in the treatment of chloramphenicol (CAP) wastewater was investigated. Experimental results demonstrated that Fe3O4@C not only enhanced chemical oxygen demand (COD) removal efficiency and biogas production by 2.42-13.18% and by 7.53%-23.25%, respectively, but also reduced the inhibition of microbial activity caused by toxic substances and the secretion of extracellular polymeric substances (EPS) by microorganisms responding to adverse environments. The reinforcing capability of Fe3O4@C increased with the rise in Fe3O4 content. Furthermore, High-throughput pyrosequencing illustrated that Fe3O4@C enhanced the relative abundance of Methanobacterium, a hydrogen-utilizing methanogen capable of participating in direct interspecies electron transfer (DIET), by 5%. Metagenomic analysis indicated that Fe3O4@C improved the decomposition of complex organics into simpler compounds by elevating functional genes encoding key enzymes associated with organic matter metabolism, acetogenesis, and hydrogenophilic methanogenesis pathways. These findings suggest that Fe3O4@C have the potential to strengthen both the hydrogenophilic methanogenesis and DIET processes. This insight offers a novel perspective on the anaerobic bioaugmentation of high-concentration refractory organic wastewater.

Core-Shell Fe3O4@C Nanoparticles as Highly Effective T2 Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies.

Magnetite nanoparticles (Fe3O4 NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell Fe3O4@C NPs (core = Fe3O4 NPs and shell = amorphous carbons, davg = 35.1 nm) were synthesized in an aqueous solution. Carbon coating terminated with hydrophilic -OH and -COOH groups imparted excellent biocompatibility and hydrophilicity to the NPs, making them suitable for biomedical applications. The Fe3O4@C NPs exhibited ideal relaxometric properties for T2 magnetic resonance imaging (MRI) contrast agents (i.e., high transverse and negligible longitudinal water proton spin relaxivities), making them exclusively induce only T2 relaxation. Their T2 MRI performance as contrast agents was confirmed in vivo by measuring T2 MR images in mice before and after intravenous injection.

Magnetic behavior of Fe3O4@C nanofibers by a facile co-axial electrospinning method.

Co-axially electrospun, magnetic Fe3O4@carbon (Fe3O4@C) nanofibers comprising Fe3O4particles in the core and carbon in the shell have been fabricated and their performances as magnetic material have been studied. The electrospun Fe3O4@C nanofibers have been characterized with x-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscope, x-ray photoelectron spectroscope (XPS), and superconducting quantum interference device magnetometer. The structural and microstructural analysis has given a brief idea about the pure Fe3O4and C phase formation and also the existence of smooth and continuous morphology of Fe3O4@C nanofibers. It has been shown that there exist two different oxidation states of Fe in the XPS spectrum. The magnetization hysteresis loop has been observed at low temperatures (5 K, 100 K) as well as at room temperature (300 K) which gives different magnetic parameters. Temperature dependent magnetic measurements (from 5 to 300 K) suggest the existence of Verwey transition for lower percentage of iron oxide content.

Urchin-like Fe3O4@C hollow spheres with core-shell structure: Controllable synthesis and microwave absorption.

The steadily increasing use of microwave stealth materials in aerospace flying vehicles needs the development of lightweight absorbers with low density and high thermal stability for printing or spraying. In that regard, the structural designability of typical microwave absorbers made of Fe3O4 seems to be a significant roadmap. In this work, a hollow spherical structure with a uniform carbon shell around the urchin-like Fe3O4 core (Fe3O4@C) was produced via a two-step hydrothermal method and annealing. The Fe3O4@C absorber exhibited a strong minimum reflection loss (RLmin) of -73.5 dB at the matching thickness of 3.23 mm. The maximum effective absorption bandwidth (EABmax) was 4.78 GHz at 4.55 mm. The proposed urchin-like core-shell structure was shown to provide good impedance matching and electromagnetic loss ability due to the synergistic effect of Fe3O4 and C. In particular, the urchin-like structure increases the heterogeneous interfaces and effectively improves their polarization and relaxation. On the other hand, it reduces the density of the absorber and enhances multiple scattering attenuations of electromagnetic waves (EMWs). Therefore, the findings of the present study open up prospects for the design of high-efficiency lightweight microwave absorbers with specialized structures.

As(III) removal from aqueous solutions using simultaneous oxidation and adsorption process by hierarchically magnetic flower-like Fe3O4@C-dot@MnO2 nanocomposite.

In the present study, a magnetic flower-like Fe3O4@C-dot@MnO2 nanocomposite was synthesized by hydrothermal method and applied for As(III) removal by oxidation and adsorption process. Individual property of the entire material (i.e. magnetic property of Fe3O4, mesoporous surface property of C-dot and oxidation property of MnO2) make the composite efficient with good adsorption capacity for As(III) adsorption. The Fe3O4@C-dot@MnO2 nanocomposite had a saturation magnetization of 26.37 emu/g and it magnetically separated within 40 s. The Fe3O4@C-dot@MnO2 nanocomposite was able to reduce the 0.5 mg/L concentration of As(III) to 0.001 mg/L in just 150 min at pH 3. Pseudo-second-order kinetic and Langmuir isotherm model agreed with experimental data. The uptake capacity of Fe3O4@C-dot@MnO2 nanocomposite was 42.68 mg/g. The anions like chloride, sulphate and nitrate did not show any effect on removal but carbonate and phosphate influenced the As(III) removal rate. Regeneration was studied with NaOH and NaClO solution and the adsorbent was used for repeated five cycles above 80% removal capacity. The XPS studies proposed that As(III) first oxidized to As(V) then adsorb on the composite surface. This study shows the potential applicability of Fe3O4@C-dot@MnO2 nanocomposite to high extent and gives a suitable path for the proficient removal of As(III) from wastewater.

A vortex-enhanced magnetic solid phase extraction for the selective enrichment of four quaternary ammonium alkaloids from Zanthoxyli Radix.

Zanthoxyli Radix, the dried root of Zanthozylum nitidum (Roxb.) DC, one of traditional Chinese medicines (TCMs), exhibits various pharmacological activities such as anti-bacterial, anti-inflammatory, anti-tumor, analgesic activity. A sustainable vortex-enhanced magnetic solid phase extraction (VE-MSPE) method combined with ultra-high performance liquid chromatography (UHPLC) was established to enrich and analyze the bioactive quaternary ammonium alkaloids (QAAs) of Zanthoxyli Radix. Fe3O4@C@CMCS magnetic nanoparticles (MNPs) was first synthesized for selectively adsorbing target QAAs (magnolinine, sanguinarine, nitidine chloride and chelerythrine), which possess excellent adsorption performance after being reused 10 times. The results revealed that the great adsorption rate of Fe3O4@C@CMCS MNPs for the four QAAs could reach 55.1-78.7 %. In addition, a reliable linear relationship (r ≥ 0.9995) and good recovery (97.5-104 %) was obtained. Consequently, the VE-MSPE method applying Fe3O4@C@CMCS MNPs as a sustainable adsorbent exhibited great potential in the selective enrichment of QAAs in TCM.

Recyclable magnetic Fe3O4@C for methylene blue removal under microwave-induced reaction system.

The reclamation and removal of organic pollutants are difficult issues of world concern. In this study, a microwave-induced reaction system (MIRS) is applied to synthesize the multifunctional composite of Fe3O4@C, which is employed to adsorb, separate and catalytic oxide the typical organic dye of methylene blue (MB). SEM, TEM, VSM, XPS, pHpzc, and N2 adsorption performances are carried out to characterize the Fe3O4@C. Results show that the Fe3O4@C mainly consists of activated Fe-O-C microspheres, which possess plentiful mesopore and macropore structures on surfaces. Batch adsorption experiments were carried out by varying key reaction conditions to optimize these. The maximum adsorption capacity of MB onto the Fe3O4@C was 305.0 mg g-1 in 120 min, at pH 10, and at a temperature of 323 K. MIRS was also assisted to regenerate the spent Fe3O4@C which presented good regeneration efficiency by sustaining 16 regeneration cycles without any oxidizing agent. SEM images and FTIR spectrum verified that MB would translate into greater or smaller-sized carbon microspheres. What's more, the adsorption of MB onto both initial and the 16th regenerated Fe3O4@C obeyed the Langmuir isotherm model and followed the pseudo-second-order adsorption kinetics, indicating the adsorptive stability after regeneration. In this study, the Fe3O4@C combined with MIRS may be one innovative strategy for organic pollutants' complete removal in the future.

Yolk-shell Co3 O4 @Fe3 O4 /C Nanocomposites as a Heterogeneous Fenton-like Catalyst for Organic Dye Removal.

The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites with Co3 O4 as the core, Fe3 O4 /C as the shell, and a cavity structure were synthesized by the hard template method. The physical and chemical properties of the composites were characterized by SEM, TEM, XRD, TGA, XPS, BET, and VSM. The specific surface area of yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites is 175.9 m2  g-1 , showing superparamagnetic properties. The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites were used as heterogeneous Fenton catalysts to activate peroxymonosulfate (PMS) to degrade MB, which showed high catalytic degradation performance. The degradation rate of MB reached 100 % within 30 min under the circumstances of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites dosage of 0.1 g L-1 , the PMS dosage of 1.0 g L-1 , the initial MB concentration of 100 mg L-1 , an initial pH of 5.5, and a temperature of 30±2 °C. The enhanced catalytic performance of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be attributed to the synergistic effect of the two catalytically active materials and the middle cavity. The effects of different operating parameters and co-existing anion species on MB degradation were also investigated. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed that the formation of SO4 ⋅- in the yolk-shell Co3 O4 @Fe3 O4 /C/PMS system contributes to MB degradation. In addition, yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be easily separated from the pollutant solution under the action of an external magnetic field, and the degradation rate of MB can still reach 98 % after five cycles, indicating that it has good stability and reusability and has broad application prospects in the field of water purification.

Synthesis of 2-Nitro-2,3-Unsaturated Glycosides by a Nanomagnetic Catalyst Fe3O4@C@Fe(III).

A sustainable magnetic core-shell nanocatalyst Fe3O4@C@Fe(III) was successfully applied in the synthesis of a series of 2-nitro-2,3-unsaturated O-glycosides with excellent yields (up to 89%) and high stereoselectivity (α:ß > 19:1). The substrate ranges are widely applicable, including different kinds of alcohols and even structurally complex acceptors. In addition, phenols could be applied in good yields. Moreover, the catalyst could be easily separated from the reaction by the application of an external magnetic force and reused a minimum of five times without any significant decrease in catalytic performance.

Carbon Double Coated Fe3O4@C@C Nanoparticles: Morphology Features, Magnetic Properties, Dye Adsorption.

This work is devoted to the study of magnetic Fe3O4 nanoparticles doubly coated with carbon. First, Fe3O4@C nanoparticles were synthesized by thermal decomposition. Then these synthesized nanoparticles, 20-30 nm in size were processed in a solution of glucose at 200 °C during 12 h, which led to an unexpected phenomenon-the nanoparticles self-assembled into large conglomerates of a regular shape of about 300 nm in size. The morphology and features of the magnetic properties of the obtained hybrid nanoparticles were characterized by transmission electron microscopy, differential thermo-gravimetric analysis, vibrating sample magnetometer, magnetic circular dichroism and Mössbauer spectroscopy. It was shown that the magnetic core of Fe3O4@C nanoparticles was nano-crystalline, corresponding to the Fe3O4 phase. The Fe3O4@C@C nanoparticles presumably contain Fe3O4 phase (80%) with admixture of maghemite (20%), the thickness of the carbon shell in the first case was of about 2-4 nm. The formation of very large nanoparticle conglomerates with a linear size up to 300 nm and of the same regular shape is a remarkable peculiarity of the Fe3O4@C@C nanoparticles. Adsorption of organic dyes from water by the studied nanoparticles was also studied. The best candidates for the removal of dyes were Fe3O4@C@C nanoparticles. The kinetic data showed that the adsorption processes were associated with the pseudo-second order mechanism for cationic dye methylene blue (MB) and anionic dye Congo red (CR). The equilibrium data were more consistent with the Langmuir isotherm and were perfectly described by the Langmuir-Freundlich model.

Highly efficient recovery of heavy rare earth elements by using an amino-functionalized magnetic graphene oxide with acid and base resistance.

In the application of various magnetic materials for water treatment, control of surface resistance to acid and alkali corrosion remains largely overlooked, which could greatly extend their service life. We herein prepare amino grafted magnetic graphene oxide composites using a simple one-step cross-link reaction between the graphene oxide and magnetic Fe3O4/C nanoparticles. The as-prepared magnetic graphene oxide composites have long-term stability under acid and alkali solutions and shows an excellent performance in removing Ho(III), a representative rare earth element (REE) from water. The observed adsorption capacity of 72.1 mg Ho(III)/g exceeded that of most magnetic materials previously reported. Regeneration of the magnetic composites was realized in acid and alkali solutions but their structural integrity and physicochemical properties retained even after 18 adsorption-desorption cycles. The current adsorbent also shows excellent adsorption performance for other heavy REEs, such as Er(III), Eu(III), Lu(III), Tm(III), Y(III) and Yb(III). This work can provide a new strategy for constructing an acid and base resistance magnetic graphene oxide for the high-efficient recovery of heavy REEs from aqueous solution.

Remediation of Pb-Contaminated Soil Using a Novel Magnetic Nanomaterial Immobilization Agent.

The management of heavy metal contaminated soil has received extensive research attention. In this study, a novel immobilization agent (SiO2@Fe3O4@C-COOH) was combined with traditional immobilization agents (TIAs), i.e., CaO, organic matter (OM), and calcium superphosphate (CSP), and used to remediate Pb-contaminated soil. The immobilization effects of Pb in soil was evaluated through pot experiments involving wheat cultivation. The results indicated that SiO2@Fe3O4@C-COOH delivered a higher Pb immobilization efficiency than did TIAs such as CaO, OM, and CSP. The application of SiO2@Fe3O4@C-COOH in combination with TIAs (CaO, OM, and CSP) synergistically enhanced the Pb immobilization efficiency of the soil to 85.10%. Further, joint application in a 54.19% reduction of Pb content in wheat roots, a 65.78% reduction in stems, and a 47.96% in leaves. Thus, the combined application of SiO2@Fe3O4@C-COOH and TIAs significantly reduced the bioavailability of Pb, achieved the purpose of Pb stabilization and soil remediation, and has the potential for wide-spread application in the remediation of Pb-contaminated soils.

Magnetic solid-phase extraction based on zirconium-based metal-organic frameworks for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices.

A novel multi-residue method, magnetic solid-phase extraction combined with LC-MS/MS, was proposed for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices. Fe3O4@C@UiO-66 was firstly used to extract and enrich pesticides, showing excellent adsorption capacity, which was proved by adsorption kinetic and thermodynamic experiments. Multiple extraction parameters were optimized by Plackett-Burman and Box-Behnken design. Under optimized conditions, good linearity (1.0-200 ng L-1, R2 ≥ 0.9953) for all analytes, detection limits (0.10 to 0.35 ng L-1), quantitation limits (0.35 to 1.00 ng L-1), recoveries (83.68-95.99%), and precision (intra-day RSD ≤ 7.06%, inter-day RSD ≤ 9.40%) were obtained, meeting the requirements of pesticides residues analysis. It is worth mentioning that eight chiral pesticides can be separated quickly within 19 min. The above results indicate that the proposed method with satisfactory sensitivity and accuracy has the potential for routine analysis of chiral pesticide residues in aqueous samples.

Triple-enzyme mimetic activity of Fe3O4@C@MnO2 composites derived from metal-organic frameworks and their application to colorimetric biosensing of dopamine.

Novel Fe3O4@C@MnO2 composites were successfully synthesized for the first time via an interfacial reaction between magnetic porous carbon and KMnO4, in which the magnetic porous carbon was derived from the pyrolysis of Fe-MIL-88A under N2 atmosphere. Interestingly, the obtained Fe3O4@C@MnO2 composites were found to have triple-enzyme mimetic activity including peroxidase-like, catalase-like, and oxidase-like activity. As a peroxidase mimic, Fe3O4@C@MnO2 composites could catalyze the oxidation of TMB into a blue oxidized product by H2O2. As a catalase mimic, Fe3O4@C@MnO2 could catalyze the decomposition of H2O2 to generate O2 and H2O. As an oxidase mimic, Fe3O4@C@MnO2 could catalyze the direct oxidation of TMB to produce a blue oxidized product without H2O2. Reactive oxygen species measurements revealed that the oxidase-like activity originated from 1O2 and O2-∙and little∙OH generated by the dissolved oxygen, which was catalyzed by the Fe3O4@C@MnO2 in the TMB oxidation reaction. The oxidase-like activity of Fe3O4@C@MnO2 was investigated in detail. Under the optimized conditions, a rapid, sensitive, visual colorimetric method for dopamine detection was developed based on the inhibitory effect of dopamine on the oxidase-like activity. The proposed method allows for dopamine detection with a limit of detection of 0.034 µM and a linear range of 0.125-10 µM. This new colorimetric method was successfully used for the determination of dopamine in human blood samples.

Fe3O4 nanoparticles coated with ultra-thin carbon layer for polarization-controlled microwave absorption performance.

The sufficient interface contact in the composite absorbing material is beneficial to increase the dielectric loss and promote the microwave absorption performance. In this paper, the composite nanoparticles (NPs), Fe3O4 covered with ultra-thin carbon layer (Fe3O4/C), were synthesized by simple high temperature solution-phase and subsequent high-temperature steam carbonization methods. Small size Fe3O4/C composite NPs have large heterogeneous interfaces, which can control the polarization loss of composite NPs through the method of interface regulation and achieve high microwave absorption performance. The strongest reflection loss of the composite NPs with an average particle size of 52 nm can reach -58.5 dB at 14.88 GHz with a thickness of 2 mm, and the corresponding effective absorption (RL ≤ -10 dB) bandwidth (EAB) is 5.63 GHz (12.37-18 GHz). In particular, the high-efficiency absorption (RL ≤ -20 dB) bandwidth of Fe3O4/C can reach 15.44 GHz (2-17.44 GHz) with a thickness of 1.7-10 mm. The current method for controlling polarization loss provide a meaningful reference for future microwave absorption research.

3D flower-liked Fe3O4/C for highly sensitive magnetic dispersive solid-phase extraction of four trace non-steroidal anti-inflammatory drugs.

A low cost-effective and simple synthesis method was adopted to acquire three-dimensional flower-like structure Fe3O4/C that has large specific area, suitable pore structure and sufficient saturation magnetism. The obtained Fe3O4/C exhibits outstanding preconcentration ability and was applied to extracting non-steroidal anti-inflammatory drugs from complex environmental and biological samples. The parameters of magnetic solid-phase extraction were optimized by univariate and multivariate methods (Box-Behnken design). The high degree of linearity from 2.5 to 1000.0 ng mL-1 (R2 ≥ 0.9976), the limits of detection from 0.25 to 0.5 ng mL- 1 (S/N = 3), and the limits of quantitation from 1.0 to 2.0 ng mL- 1 (S/N = 10) were yielded by adopting this novel method after the optimization. Moreover, the recoveries of non-steroidal anti-inflammatory drugs from 89.6 to 107.0% were acquired in spiked plasma, urine and lake samples. In addition, the adsorption of non-steroidal anti-inflammatory drugs on Fe3O4/C was explored by adsorption isotherms and kinetic studies. Furthermore, the adsorption mechanism for non-steroidal anti-inflammatory drugs by Fe3O4/C was proposed, which was hydrogen bonding and π-π interaction between non-steroidal anti-inflammatory drugs and Fe3O4/C. Graphical abstract.

Fe3O4@C Nanoparticles Synthesized by In Situ Solid-Phase Method for Removal of Methylene Blue.

Fe3O4@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO4, FeS2, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results indicated that the maximum adsorption capacity of the Fe3O4@C nanoparticles was 18.52 mg/g, and that the adsorption process was exothermic. Additionally, by employing H2O2 as the initiator of a Fenton-like reaction, the removal efficiency of 100 mg/L MB reached ~99% with Fe3O4@C nanoparticles, while that of MB was only ~34% using pure Fe3O4 nanoparticles. The mechanism of H2O2 activated on the Fe3O4@C nanoparticles and the possible degradation pathways of MB are discussed. The Fe3O4@C nanoparticles retained high catalytic activity after five usage cycles. This work describes a facile method for producing Fe3O4@C nanoparticles with excellent catalytic reactivity, and therefore, represents a promising approach for the industrial production of Fe3O4@C nanoparticles for the treatment of high concentrations of dyes in wastewater.

Catalytic hairpin assembly indirectly covalent on Fe3O4@C nanoparticles with signal amplification for intracellular detection of miRNA.

Fluorescence resonance energy transfer, a promising method for in situ imaging of miRNA in living cells, has intrinsic limitation on sensitivity and selectivity. Herein, a fluorescent amplification strategy based on catalyzed hairpin assembly indirectly covalent on Fe3O4@C nanoparticles via short single-stranded DNA was investigated for cellular miRNA detection in living cells, integrating non-enzyme target-active releasing for amplifying the signal output, highly quenching efficiency of Fe3O4@C nanoparticles with low background, ssDNA assisted fluorescent group-fueled chain releasing from Fe3O4@C nanoparticles with enhanced fluorescence response. The designed platform exhibits highly sensitive in a wide linear concentration range of 0.450 pM-190 pM and is highly specific for miRNA-20a detection with the ability of discriminating one mistake base. Additionally, the CHA-Fe3O4@C was successfully applied in imaging visualization of miRNA-20a in the living cell. The strategy provides a promising bioassay approach for clinical research.

Structure-tunable Mn3O4-Fe3O4@C hybrids for high-performance supercapacitor.

Controlling the morphology and structure of nanomaterials is of great importance for enhancing the electrochemical properties. In the paper, Mn3O4-Fe3O4@C hybrids with different architectures were synthesized by incubation of electrospun FeOx-containing carbon fiber (Fe-CNF) in KMnO4 solution followed by annealing. The presence of FeOx on the CNF plays a vital role in determining the morphology and structure of the final hybrids, and the Mn3O4-Fe3O4@C hybrids with half-tube, tube and oolite-filled fibers are formed conveniently by tuning Fe content in the carbon fiber precursor. The good conductivity of fiber and various redox states of Mn and Fe afford the facile charge transfer and excellent reversible redox properties, thus enhancing the capacitor performance. The oolite-filled Mn3O4-Fe3O4@C with tubular structure exhibited a high specific capacitance of 178 F g-1 at a discharge rate of 1 A g-1. This capacitor electrode has an excellent cyclic stability with 95% capacitance retention after 1000 cycles at 3 A g-1. This work provides a very simple strategy to tune the unique nanostructures of metal oxide on Fe-CNF for high-performance supercapacitor application in the future.