Mn-doped Fe3O4 Research Articles

Comparative study on structural, morphological, and optical properties of MS/Fe3O4 nanocomposites and M-doped Fe3O4 nanopowders (M = Mn, Zn)

In the present work, the un-doped, M-doped magnetite (Fe3O4); (M = Mn, Zn), and MS/Fe3O4 composite nanopowders with a cubic spinel-type structure and average crystallite size range from 8.30 to 12.33 nm were synthesized by co-precipitation method. The FESEM images revealed the shape of particles are spherical with a grain size in the range of 33.44–49.77 nm. Through the analysis of reflectance data using Tauc’s model, the direct band gap energies of 2.98 eV, 2.93 eV, 3.01 eV, 2.85 eV, and 2.95 eV were determined for Un-doped Fe3O4, Mn-doped Fe3O4, Zn-doped Fe3O4, MnS/Fe3O4 composite, and ZnS/Fe3O4 composite NPs respectively. The parameters such as extinction coefficient and refractive index of the nanoparticles were computed by the Kramers–Kronig (K–K) method. Non-linear optical (NLO) parameters were computed from DRS data using the Wemple–Di-Domenico (WDD) model. The calculated third-order NLO susceptibility χ(3)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\chi }^{(3)}$$\\end{document} and also electrical susceptibility χe\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\chi }_{\\left(e\\right)}$$\\end{document} represented the maximum value for MnS/Fe3O4 composite NPs compared to the other samples. Considering the advanced optical parameters of MS/Fe3O4 composite samples, these particles can be suitable candidates for non-linear optical applications.

Porous Mn-doped Fe3O4 as lithium-ion battery anode via low-temperature combustion synthesis

The preparation of Mn-doped Fe3O4 was carried out using the low-temperature combustion synthesis (LCS) method through the addition of Mn2+ to the ferric nitrate-glycine system. Here, we investigate the mechanism of the redox reaction involving Fe3+ and Mn2+ ions, and the results reveal that for the synthesis of porous Mn-doped Fe3O4, the presence of Mn2+ in the raw material is necessary. The carbon source, such as ethylene glycol, glucose, and polyethylene glycol-4000, serves as both reducing and complexing agent, leading to the formation of more pores during the combustion reaction. Increased specific surface area of combustion products. By conducting a LCS reaction in a solution with added ethylene glycol, Mn-doped Fe3O4 was obtained for lithium ions batteries as anode material, at current density of 5 A g−1, it demonstrates an impressive capacity retention rate of 90% with a high capacity of 452.5 mA h g−1 after 650 cycles. Similarly, Mn-doped Fe3O4 obtained with the addition of polyethylene glycol shows a capacity retention rate of 89.7% after 1500 cycles. Our findings provide a new and innovative method for the preparation of manganese ferrites with a porous structure and a new research approach for developing metal oxide anode materials.

Removal of trace concentration Sb(V) in textile wastewater by Mn-doped Fe3O4: The mechanisms of Mn affect adsorption performance

Mn-doped Fe3O4 with different Mn/Fe ratios were synthesized to remove 200 μg/L aqueous Sb(V) in simulated textile wastewater under neutral pH. The synthesized materials were characterized by XRD, XPS, and FTIR to confirm the Mn had been successfully doped into the lattice of Fe3O4. The optimum ratio of initial Mn/Fe appeared at 1:3, with the actual Mn/Fe ratio of 0.22, which was determined by the acid digest experiment. In contrast to the original Fe3O4, Mn doping increased the maximum adsorption capacity from 64.66 mg/g to 176.03 mg/g, and the adsorption capacity for 200 μg/L Sb(V) was enhanced from 0.74 mg/g to 1.51 mg/g. Mn affects the adsorption performance of materials through three main methods, decreased the particle size by hampering the crystal growth, which brought increased specific surface area leading to a higher adsorption capacity; reduced the distribution of Fe on the surface of materials, which results in lower adsorption capacity; increased the binding energy of Fe–O bonds, thus reducing the number of hydroxyl groups on the surface of materials, thereby reduce the adsorption capacity of the material. Synthesized Mn-doped Fe3O4 possesses good magnetic separation performance and reusability, thus could be a promising adsorbent to remove trace concentration Sb(V) in aqueous solutions.

Hollow Meso-crystalline Mn-doped Fe3O4 Fenton-like catalysis for ciprofloxacin degradation: Applications in water purification on wide pH range

Herein, an unprecedented heterogeneous Fenton-like catalyst with a hollow meso-crystalline Fe3O4 catalyst doped with Mn was prepared for the first time through a one-pot method, which can effectively activate H2O2 in a wide pH range and has good stability. The results show the catalyst can achieve rapid degradation of ciprofloxacin (CIP) under the conditions of pH = 4.5 to pH = 9.5, which greatly expands the application conditions of Fenton. Sufficient experimental exploration clearly demonstrated that the uniform doping of Mn in Fe3O4 crystal lattice, and the formation process of Mn-doped Fe3O4 hollow meso-crystalline microspheres was reasonably analyzed based on Ostwald curing theory and bubble theory. The dual reaction center theory reasonably explains the reaction mechanism of the catalyst. The H2O2 adsorbed on the electron-rich Fe center is reduced to •OH, while the H2O2 adsorbed on the electron-deficient Mn center is oxidized to •O2–/HO2•, •OH and •O2–/HO2• are further converted to 1O2, which participates in involved in the degradation process of CIP. This research provides new ideas for the rational design of catalysts that can apply the heterogeneous Fenton reaction to actual water purification in a wide pH range.

Mn-Fe3O4 nanoparticles anchored on the urushiol functionalized 3D-graphene for the electrochemical detection of 4-nitrophenol

Preparation of highly active and cost-effective electrode materials is of great interest in electrochemical detection. In this study, a simple urushiol-templated solvothermal method combined with calcination was proposed to fabricate N-doped three-dimensional graphene (3D-G) with Mn-doped Fe3O4 nanoparticles loaded on the surface (Mn-Fe3O4/3D-G). Because of the large active surface area, porous channel and high loading ratio of Mn-Fe3O4 nanoparticles, as-prepared Mn-Fe3O4/3D-G sensor showed high activity on the determination of 4-nitrophenol (4-NP), which are much improved from the control un-modified samples. The wide linear concentration range (5–100 μM), low detection limit (19 nM) and satisfactory recovery of 4-NP in various water samples (98.38–100.41%) indicated that the Mn-Fe3O4/3D-G electrode can be potentially used for real-world applications. This study gives a simple but meaningful strategy for constructing transition metal oxide/graphene composite materials with high electrocatalytic activity.

Factors affecting the heating efficiency of Mn-doped Fe3O4 nanoparticles

MnxFe3-xO4 (x = 0, 0.1, 0.3 and 0.5) nanoparticles were synthesized using the co-precipitation method and its structural and magnetic properties were correlated to the heating characteristics in an ac magnetic field. The effective magnetic anisotropy of the samples measured using electron spin resonance was between 15.3 and 16.5 kJ/m3 with Mn-doping. The effective magnetic anisotropy increased to 31.3 kJ/m3 on doping Fe3O4 with Co. The hyperthermia response of the samples was tested using infrared thermography and the effective specific absorption rate (ESAR) was obtained in the range of 15–21 × 10−9 W/gOe2Hz. The ESAR decreased when the effective magnetic anisotropy was 16.5 kJ/m3, as well as when it increased to 31.3 kJ/m3. The effect of magnetic anisotropy and polydispersity on the hyperthermic efficiency was intensively analyzed employing theoretical models.

DFT insights to mercury species mechanism on pure and Mn doped Fe3O4(1 1 1) surfaces

The interaction between mercury species and Fe3O4(1 1 1), Mn doped Fe3O4(1 1 1) surfaces, with Feoct2- termination has been calculated by density functional theory (DFT). Different adsorption sites and placement of adsorbates, potential catalytic oxidation of Hg0 by the adsorbed Cl atoms on the Mn-doped Fe3O4 surface have been considered. The result revealed Hg0 physical and weak chemical adsorption on both pure surface and Mn-doped surface. Horizontally placed HgCl and HgCl2 were better chemisorbed on the surface. Although complete dissociation and partial dissociation occurred during the adsorption process of oxidation mercury, configurations of complete dissociation were more stable than that of partial dissociation. HgCl was chemically adsorbed on both Fe3O4 (1 1 1) and Mn doped Fe3O4 (1 1 1) surface through breaking into two atoms, and HgCl2 adsorbed through three ones. Both of the Cl atom and Hg atom tended to bind to the transition metals on the surface. When Mn and Fe atoms coexisted on the surface, Cl atoms preferred to bind to Mn atoms. Besides, all the decomposition reaction was exothermic process according to the negative values of adsorption energy.

Nonisothermal cure kinetics of epoxy/MnxFe3-xO4 nanocomposites

Nonisothermal cure kinetic of epoxy containing bare and Mn doped Fe3O4 nanoparticles was studied through differential scanning calorimetry (DSC). The evolution of the apparent activation energy (Eα) as a function of the extent of curing reaction was evaluated by using model-free integral Kissinger and differential Friedman isoconversional methods. Mn2+ cations in the MnxFe3-xO4 were the reason for facilitated epoxy curing reaction, as proved by a lower values of Eα obtained for the corresponding nanocomposite. Moreover, MnxFe3-xO4 nanoparticles increased the average autocatalytic reaction order from 0.48 for neat epoxy to 0.52 for epoxy/Mn-Fe3O4 nanocomposite due to the participation of hydroxyl groups on the surface of nanoparticle in epoxide ring opening. Addition of Fe3O4 and Mn-Fe3O4 nanoparticles decreased collisions between the curing moieties, as reflected in a drop in the frequency factor from ca. 18.9 for neat epoxy to 13.4 and 14.9 for epoxy nanocomposites containing 0.1 wt.% of Fe3O4 and Mn-Fe3O4, respectively.

Magnetic Mn-Doped Fe3O4 hollow Microsphere/RGO heterogeneous Photo-Fenton Catalyst for high efficiency degradation of organic pollutant at neutral pH

Development of high-efficiency, low-cost and environmentally friend catalyst for degradation of organic pollutant in water is still a challenge issue. In this research, we prepared a novel Mn-doped Fe3O4 magnetic hollow microsphere/reduced oxide graphene (RGO) hybrid (Mn-Fe3O4/RGO) by a facile solvothermal process followed by a reduction of GO via NaBH4. The as-prepared Mn-Fe3O4/RGO is used as a heterogeneous Photo-Fenton catalyst for degrading Rhodamine B (RhB) and exhibits high efficiency degradation about 96.4% with the low dosage concentration of catalyst 0.2 g L−1 in the presence of H2O2 at the natural pH (~6.5) within 80 min under UV–vis illumination, while the removal efficiency is 91% and 85% at pH 2 and 11, respectively. Furthermore, this novel magnetic Photo-Fenton catalyst remains high degradation efficiency of about 90% after ten cycles and can be easily separated from the solution via an external magnetic field, showing an excellent recyclability, a long-term chemical stability and a great potential for practical wastewater treatment application.

Thiol modified Au nanoparticles grafted manganese doped magnetic iron oxide nanoparticles for spectrometric determination of short-term release of mercury and copper from dental amalgam in saliva

Abstract A new adsorbent, ethylene glycol bisthioglycolate modified gold nanoparticles grafted Mn doped Fe3O4 nanoparticles (EGBTG-Au@Mn-Fe3O4 NPs) were synthesized through chemical precipitation followed by an oxidative Mn doping process to use for extraction and preconcentration of trace amounts of Hg, and Cu ions in artificial and natural saliva. The prepared adsorbent was characterized by TEM, BET, XRD and VSM techniques. Fusayama artificial saliva was prepared and used as blank sample and natural saliva was collected from nine volunteers ranged from 15-29 years old who exposed to posterior decayed teeth amalgam filling and short-term release of heavy metal ions was assessed in 24, 72 and 96 h after filling. Various factors affecting extraction/desorption efficiency of target ions have been investigated and analytical characteristics of the recommended method were determined. Detection limits of 0.12 and 0.09 ng mL-1 were obtained for Cu and Hg ions respectively with preconcentration factor of 96. The results revealed that the adsorbent has high adsorbent capacity and good reusability for extraction/preconcentration of target ions in relatively high saline solution like biological fluids.

Dye degradation property of cobalt and manganese doped iron oxide nanoparticles

Cobalt (Co) and manganese (Mn) doped iron oxide (Fe3O4) nanoparticles were synthesized using co-precipitation. Mn and Co (8 and 16%) were added gradually to Fe3O4 nanoparticles followed by annealing at 1000 °C. Co and Mn-doped Fe3O4 revealed cubic structure well matched to JCPDS # 01-089-2807 and 01-077-0426 respectively with crystallite size 8–21 nm confirmed by XRD. Mixing of Co and Mn improved absorption range toward longer wavelength as evident from UV–Vis spectroscopy. However, morphology of doped NPs was spherical and agglomerated visualized through field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). Moreover, presence of metal–oxygen bond vibration in Co and Mn doped NPs was observed at 600 nm. On the other hand, saturation magnetization was highest for 16% Co-doped Fe3O4 attributed to excellent magnetic nature of cobalt nanoparticles. These findings showed superior performance of Co-doped magnetite compared to undoped and has been an interesting candidate to be used as nanocatalyst to replace conventional waste water management methods.

Multifunctional Nanoflowers for Simultaneous Multimodal Imaging and High-Sensitivity Chemo-Photothermal Treatment.

Liver cancer is currently among the most challenging cancers to diagnose and treat. It is of prime importance to minimize the side effects on healthy tissues and reduce drug resistance for precise diagnoses and effective treatment of liver cancer. Herein, we report a facile but high-yield approach to fabricate a multifunctional nanomaterial through the loading of chitosan and metformin on Mn-doped Fe3O4@MoS2 nanoflowers. Mn-doped Fe3O4 cores are used as simultaneous T1/T2 magnetic resonance imaging (MRI) agents for sensitive and accurate cancer diagnosis, while MoS2 nanosheets are used as effective near-infrared photothermal conversion agents for potential photothermal therapy. The surface-functionalized chitosan was able not only to improve the dispersibility of Mn-doped Fe3O4@MoS2 nanoflowers in biofluids and increase their biocompatibility, but also to significantly enhance the photothermal effect. Furthermore, metformin loading led to high suppression and eradication of hepatoma cells when photothermally sensitized, but exhibited negligible effects on normal liver cells. Due to its excellent combination of T1/T2 MRI properties with sensitive chemotherapeutic and photothermal effects, our study highlights the promise of developing multifunctional nanomaterials for accurate multimodal imaging-guided, and highly sensitive therapy of liver cancer.

Nonisothermal decomposition kinetics of pure and Mn-doped Fe3O4 nanoparticles

Pure Fe3O4 and Mn-doped Fe3O4 nanoparticles were synthesized by simple wet chemical reduction technique using nontoxic precursors. Manganese doping of two concentrations, 10 and 15%, were employed. All the three synthesized nanoparticles were characterized by stoichiometry, crystal structure, and surface morphology. Thermal studies on as-synthesized nanoparticles of pure ferrite (Fe3O4) and manganese (Mn) doped ferrites were carried out. The thermal analysis of the three as-synthesized nanoparticles was done by thermogravimetric (TG), differential thermogravimetric, and differential thermal analysis techniques. All the thermal analyses were done in nitrogen atmosphere in the temperature range of 308–1233 K. All the thermocurves were recorded for three heating rates of 10, 15, and 20 K min−1. The TG curves showed three steps thermal decomposition for Fe3O4 and two steps thermal decompositions for Mn-doped Fe3O4 nanoparticles. The kinetic parameters of the three as-synthesized nanoparticles were evaluated from the thermocurves employing Kissinger–Akahira–Sunose (KAS) method. The thermocurves and evaluated kinetic parameters are discussed in this paper.

Screening and optimization of highly effective ultrasound-assisted simultaneous adsorption of cationic dyes onto Mn-doped Fe3O4-nanoparticle-loaded activated carbon

The ultrasound-assisted simultaneous adsorption of brilliant green (BG) and malachite green (MG) onto Mn-doped Fe3O4 nanoparticle-loaded activated carbon (Mn-Fe3O4-NP-AC) as a novel adsorbent was investigated and analyzed using first derivative spectrophotometry. The adsorbent was characterized using FT-IR, FE-SEM, EDX and XRD. Plackett–Burman design was applied to reduce the total number of experiments and to optimize the ultrasound-assisted simultaneous adsorption procedure, where pH, adsorbent mass and sonication time (among six tested variables) were identified as the most significant factors. The effects of significant variables were further evaluated by a central composite design under response surface methodology. The significance of independent variables and their interactions was investigated by means of the analysis of variance (ANOVA) within 95% confidence level together with Pareto chart. Using this statistical tool, the optimized ultrasound-assisted simultaneous removal of basic dyes was obtained at 7.0, 0.02g, 3min for pH, adsorbent mass, and ultrasonication time, respectively. The maximum values of BG and MG uptake under these experimental conditions were found to be 99.50 and 99.00%, respectively. The adsorption process was found to be followed by the Langmuir isotherm and pseudo-second order model using equilibrium and kinetic studies, respectively. According to Langmuir isotherm model, the maximum adsorption capacities of the adsorbent were obtained to be 101.215 and 87.566mgg−1 for MG and BG, respectively. The value of apparent energy of adsorption obtained from non-linear Dubinin–Radushkevich model (4.348 and 4.337kJmol−1 for MG and BG, respectively) suggested the physical adsorption of the dyes. The studies on the well regenerability of the adsorbent in addition to its high adsorption capacity make it promising for such adsorption applications.

Magnetic iron oxide and manganese-doped iron oxide nanoparticles for the collection of alpha-emitting radionuclides from aqueous solutions.

Magnetic nanoparticles are well known to possess chemically active surfaces and large surface areas that can be employed to extract a range of ions from aqueous solutions. Additionally, their superparamagnetic properties provide a convenient means for bulk collection of the material from solution after the targeted ions have been adsorbed. Herein, two nanoscale amphoteric metal oxides, each possessing useful magnetic attributes, were evaluated for their ability to collect trace levels of a chemically diverse range of alpha emitting radioactive isotopes (polonium (Po), radium (Ra), uranium (U), and americium (Am)) from a wide range of aqueous solutions. The nanomaterials include commercially available magnetite (Fe3O4) and magnetite modified to incorporate manganese (Mn) into the crystal structure. The chemical stability of these nanomaterials was evaluated in Hanford Site, WA ground water between the natural pH (~8) and pH 1. Whereas the magnetite was observed to have good stability over the pH range, the Mn-doped material was observed to leach Mn at low pH. The materials were evaluated in parallel to characterize their uptake performance of the alpha-emitting radionuclide spikes from ground water across a range of pH (from ~8 down to 2). In addition, radiotracer uptake experiments were performed on Columbia River water, seawater, and human urine at their natural pH and at pH 2. Despite the observed leaching of Mn from the Mn-doped nanomaterial in the lower pH range, it exhibited generally superior analyte extraction performance compared to the magnetite, and analyte uptake was observed across a broader pH range. We show that the uptake behavior of the various radiotracers on these two materials at different pH levels can generally be explained by the amphoteric nature of the nanoparticle surfaces. Finally, the rate of sorption of the radiotracers on the two materials in unacidified ground water was evaluated. The uptake curves generally indicate that equilibrium is obtained within a few minutes, which is attributed to the high surface areas of the nanomaterials and the high level of dispersion in the liquids. Overall, the results indicate that these nanomaterials may have the potential to be employed for a range of applications to extract radionuclides from aqueous solutions.

An approach to reduce the antiferromagnetic coupling of antiphase boundaries in half-metallic magnetite films

Highly conductive (∼105 μΩ cm) Mn doped epitaxial Fe3O4 films were fabricated by reactive sputtering. The larger size of magnetic domains compared to grain size with the increasing Mn content indicates that the partial antiferromagnetic coupling across the antiphase boundaries has been weakened, which was further demonstrated by the smaller exchange bias, faster saturated magnetization, and decreasing exchange interaction JAF. The decrease of antiferromagnetic strength originates from the larger Mn-O bond length than that of Fe-O bond. The first-principle calculation shows that the half-metallic feature (100% spin polarization) of Fe3O4 was unchanged with the incorporation of Mn atoms.

Preparation of highly conductive Mn-doped Fe3O4 thin films with spin polarization at room temperature using a pulsed-laser deposition technique

We report on the preparation of MnxFe3−xO4 (x=0, 0.1, or 0.5) epitaxial thin films using a pulsed-laser deposition technique. Conditions for modified film formation are discussed, in addition to their electrical and magnetic properties in relation to the potential development of room temperature spin electronics devices. The film with x=0.1 could be fabricated at a higher substrate temperature (600°C) than the Fe3O4 thin film without Mn doping. The doped films exhibited low resistivity of about 7.0×10−3(x=0.1)–9.0×10−2(x=0.5)Ωcm at room temperature. Moreover, a spin polarization of the carrier of MnxFe3−xO4 (x=0, 0.1, or 0.5) films was confirmed at room temperature by examination of anomalous Hall coefficient measurements.