Mn Fe2O4 Research Articles

Optimization of Mn-Zn ferrite doping in phosphate-based glass ceramics for enhanced hyperthermia efficiency and bioactivity

This study investigates the effects of Mn-Zn ferrite (MZF) content and heat treatment temperature on the structural, mechanical, magnetic, and bioactive properties of Na2O-CaO-P2O5 glass ceramics. Various MZF contents (5MZF, 10MZF, 20MZF, and 40MZF) were incorporated into the glass ceramics and subjected to heat treatment at different temperatures (600, 650, 700, and 800 °C). The results demonstrated that increasing the MZF content significantly enhanced the mechanical properties, including Vickers hardness, Knoop hardness, and Young's modulus. For example, the Vickers hardness values increased from 5.6 GPa in 5MZF samples to 7.1 GPa in 40MZF samples. X-ray diffraction analysis revealed the presence of major crystalline phases, such as Ca2P2O7 and Na4Ca(PO3)6, with NaFe3P3O12 and (Zn,Mn)Fe2O4 appearing in samples with higher MZF content. Magnetic measurements indicated that the 40MZF samples treated at 700 °C reached a satisfactory hyperthermia temperature of 43 °C within 16 min. Bioactivity tests showed a decrease in bioactivity with increasing MZF content, whereas cytotoxicity assays confirmed that all MZF-Na2O-CaO-P2O5 bioactive glass ceramics were non-toxic, maintaining over 100 % cell viability after 24 h. These findings suggest that MZF-containing glass ceramics have potential applications in the biomedical field, particularly when enhanced mechanical and magnetic properties are required.

Removal and recovery of phosphate by modified oyster shell and its fertilizer application

The resource utilization of oyster shell (OS) is essential for environmental and human health because its random disposal can induce the environmental pollution and disease spread. Herein, MnFe2O4 loaded-oyster shell (OMFs) was prepared by co-precipitation method for phosphate removal and recovery. The salt etching and MnFe2O4 (MF) loading improved the adsorption performance of OS, and the maximum adsorption capacity of OMF0.02 reached 87.39 mg P/g. Phosphate adsorption was dominated by chemisorption and its rate was limited by membrane diffusion and intra-particle diffusion. Phosphate adsorption by OMF0.02 was involved with electrostatic attraction, surface precipitation and ligand exchange. 98.95 % phosphate on saturated adsorbent could be desorbed by 0.1 mol/L malic acid and 92.31 % adsorbed phosphate was released by 0.5 mol/L NaHCO3. Furthermore, phosphate adsorbed on OMF0.02 was plant-available basing on the results of water spinach growth trial. All the results implied the bright prospect of OMF0.02 in phosphate removal and recovery from wastewater.

Novel Biocompatible Magnetoelectric MnFe2 O4 Core@BCZT Shell Nano-Hetero-Structures with Efficient Catalytic Performance.

Magnetoelectric (ME) small-scale robotic devices attract great interest from the scientific community due to their unique properties for biomedical applications. Here, novel ME nano hetero-structures based on the biocompatible magnetostrictive MnFe2 O4 (MFO) and ferroelectric Ba0.85 Ca0.15 Zr0.1 Ti0.9 O3 (BCZT) are developed solely via the hydrothermal method for the first time. An increase in the temperature and duration of the hydrothermal synthesis results in increasing the size, improving the purity, and inducing morphology changes of MFO nanoparticles (NPs). A successful formation of a thin epitaxial BCZT-shell with a 2-5nm thickness is confirmed on the MFO NPs(77 ± 14nm) preliminarily treated with oleic acid (OA) or polyvinylpyrrolidone (PVP), whereas no shell is revealed on the surface of pristine MFO NPs. High magnetization is revealed for the developed ME NPs based on PVP- and OA-functionalized MFO NPs (18.68 ± 0.13 and 20.74 ± 0.22 emug-1 , respectively). Moreover, ME NPs demonstrate 95% degradation of a model pollutant Rhodamine B within 2.5 h under an external AC magnetic field (150 mT, 100Hz). Thus, the developed biocompatible core-shell ME NPs of MFO and BCZT can be considered as a promising tool for non-invasive biomedical applications, environmental remediation, and hydrogen generation for renewable energy sources.

Spinel manganese nanoferrite for X-ray/gamma radiation shielding, display and antimicrobial applications

MnFe2O4 (MnFO) nanoparticles (NPs) were produced by solution combustion method. To determine phase purity, functional group, surface morphology, structural analysis, and energy band gap, synthesized NPs were evaluated using several methods. The formation of cubic MnFO NPs with the Fd−3m space group and absence of other impurities is confirmed by PXRD Bragg’s reflection. Using Wood and Tauc’s relation, the direct energy band gap is found to be 1.1 eV which was further confirmed with DFT theory. Photoluminescence, CIE and CCT plots shows, MnFO might be a good nanophosphor material for display applications. The X-ray/gamma ray shielding characteristics of MnFO nanoparticles were also evaluated in the energy range 0.081–1.332 MeV. The theoretical and the measured shielding parameters are compared. Furthermore, antimicrobial, antibacterial, antifungal and anticancer activities are discussed in detail. NPs might finds an application in the display technology, shielding of X-ray/gamma ray.

Toward a comprehensive understanding of effect of cation distribution and M2+ constituent in spinel ferrite nanocrystals MFe2O4 (M = Co, Mn, and Ni) on the electrochemical response in sensitive detection of chloramphenicol

This paper focuses on investigating the effect of the (M2+) cation constituent and the inverse degree within the lattice structure of MFe2O4 (M = Co, Mn, and Ni) nanocrystals on their electrochemical characteristics and sensing performance under the same experimental condition. Using Rietveld refinement of powder X-ray diffraction (XRD), Raman, and scanning electron microscopy (SEM), physical characterizations of CoFe2O4 (CFO), MnFe2O4 (MFO), and NiFe2O4 (NFO) are observed and analyzed. In particular, a detailed study on current response and kinetic parameters for the electron transfer reactions in the presence of K3/K4 probes and chloramphenicol (CAP) analyte is carried out, respectively, highlighting the positive influence of the electrode modification and comparing the electrochemical characteristics and sensing performance. The ordering of their electrochemical performance is listed as follows: CFO/SPE> NFO/SPE> MFO/SPE. The reason for their electrochemical performance difference is discussed in detail. Namely, the CFO sample possessing high crystallization and phase purity, uniform primary particle size, and especially wholly inversed spinel structure possessing multiple valence states (Co2+ and Co3+) on the octahedral sites offered many unique features, which are beneficial for electrical conductivity, charge transferability, surface area, and electrocatalytic active sites. Despite also being the inversed spinel structure, the NFO with the existence of impurity phases and larger grain size, as well as a lower degree of inversion than the CFO sample showed a lower enhancement in electrochemical response. However, its electrochemical signal response still is higher than that of the normal spinel MFO structure, further confirming the critical role of (M2+) cation constituent and the inverse degree to the electrochemical characteristics and sensing performance.

The effect of Zn2+ ion substitution on nanoparticles of ZnxMn(1-X) Fe2O4 (X = 0.2, 0.4, 0.6, 0.8) towards signal surface plasmon resonance (SPR)

ABSTRACT This study examined the effect of Zn2+ ion substitution on ZnxMn(1-x) Fe2O4 nanoparticles (x = 0.2, 0.4, 0.6, 0.8) towards signal Surface Plasmon Resonance (SPR). The co-precipitation method synthesised the nanoparticles at a temperature of 90°C. The X-Ray Diffraction (XRD) results showed a polycrystalline structure with a crystallite size varied from 19.05 nm to 19.77 nm. In addition, as the Zn element increased in the ZnxMn(1-x)Fe2O4 nanoparticles, the degree of crystallinity increased by 21.72%, respectively. The optical properties of the nanoparticles ZnxMn(1-x) Fe2O4 indicate absorbance at wavelengths of 330.36–331.74 nm. The absorbance level increased as the Zn element decreased, resulting a direct optical gap of 3.47 eV and an indirect optical gap of 3.23 eV. The Attenuated Total Reflection (ATR) curve in the SPR biosensor indicated a shift in the reflective angle of the Prism/Au/Air configuration, which is 47.78° on Prisma/Au/nanoparticle of Zn0.8Mn0.2Fe2O4/air by 50.75°, and the prism/Au/nanoparticle of Zn0.2Mn0.8Fe2 O4/air by 51.04°. The substitution of Zn ions in the compound Zn x Mn(1-x)Fe2O4 affects the resulting ATR curve. The shift in the SPR angle is caused by changes in the refractive index in each layer which is influenced by the concentration of each material which has an impact on the absorbance ability and photon reflectance. This research has the potential to continue with the testing of dielectric and magnetic properties, as well as special testing for biological analytes compatible with ZnxMn(1-x)Fe2O4 nanoparticles.

Synthesis and Gas Sensing Properties of Manganese Ferrite Nanoparticles by Sol - Gel Method

The purpose of this study is to determine the effect of temperature on the microstructure of Manganese Ferrite (MnFe2O4) nanoparticles. The synthesis of MnFe2O4 (MFO) nanoparticles carried out by using sol - gel citrate method followed by calcinations. The nanocomposite was characterized by means of x-ray powder diffraction. Obtained XRD measurement data was crystalline in phase with a spinel structure. Additionally, sensor performance of undoped and surface modified by 1.5 wt % Pd over MFO were studied under different operating temperature and different reducing gases such as NH3, H2S, CO and ethanol. The result reveals that material exhibit excellent sensitivity and selectivity toward ammonia gas at 1800C proving their applicability in gas sensors.

Spinel-Structured, Multi-Component Transition Metal Oxide (Ni,Co,Mn)Fe2O4−x as Long-Life Lithium-Ion Battery Anode Material

Metal oxide anode materials are affected by severe volume expansion and cracking in the charging/discharging process, resulting in low capacity and poor cycle stability, which limits their application in lithium-ion batteries (LIBs). Herein, a new strategy is uncovered for a preparing spinel-structured, multi-component transition metal oxide, (Ni,Co,Mn)Fe2O4−x, with oxygen vacancies as an LIB anode material. The as-fabricated material presented excellent reversible capacity and cycling stability, delivering a discharge capacity of 1240.2 mAh g−1 at 100 mA g−1 for 200 cycles and then at 300 mA g−1 for 300 additional cycles. It presented extremely long cycle stability even at 2 A g−1, revealing 650.5 mAh g−1 after 1200 cycles. The good lithium storage capacity can be ascribed to the entropy stabilization effect, the multi-cation synergistic effect, abundant oxygen vacancies and the spinel structure. This study provides a new opportunity to fabricate and optimize conversion-type anodes for LIBs with satisfactory electrochemical performance.

The emergence of MnFe2O4 nanosphere-based humidity sensor: a methodical investigation by scanning Kelvin probe and its deployment in multitudinous applications

In this study, the ambient temperature humidity sensing properties of solvothermally synthesized MnFe2O4 (MFO) nanospheres on interconnected comb-like silver electrodes were studied systematically.

X-ray photoelectron spectroscopy and temperature-dependent electrical transport properties of MnFe2O4-reduced graphene oxide nanocomposites

The reduced graphene oxide (rGO) sheets are assembled with MnFe2O4 (MFO) nanoparticles via an in-situ sol–gel autocombustion route to obtain MFO@rGO nanocomposites. The investigation of their structural and electrical properties is carried out through X-ray photoelectron spectroscopy (XPS) and impedance analyzer, respectively. XPS study discloses the presence of C, O, Fe, and Mn in the MFO@rGO composite, indicating the decoration of MnFe2O4 nanoparticles by rGO sheets. XPS study also reflects the mixed Fe3+/Fe2+ oxidation states of Fe and mixed Mn2+/Mn3+oxidation states of Mn in the composite. The highest value of ac conductivity (σac = 7.51 × 10−6 Ω−1 cm−1 at 1 MHz) at room temperature is obtained within the vicinity of the percolation threshold when rGO content is 20 wt%. The ac conductivity of composites increases with frequency up to 100 °C and then becomes independent of the frequency with a further increase in temperature. The impedance gradually decreases with temperature, revealing the occurrence of negative temperature coefficient of resistance effect in composites. The findings suggest that the MFO@rGO composites can be a potential nominee for the fabrication of electrodes for supercapacitors and flexible electronic devices of low resistance and high electrical conductivity for high-frequency applications.

Tailoring the electrical transport properties of ferromagnetic MnFe2O4 nanoferrite by graphene oxide: An experimental study

Herein, MnFe2O4 (MFO)-Graphene Oxide (GO) composites have been synthesized by ultrasonication method with a variation of GO content from 0 to 40 wt%. The structural tests (XRD, FTIR, HRTEM, EDX, and Raman spectroscopy) prove that the composites have high purity, contain a variety of functional groups, and have phonon modes of both GO and MFO phases. The highest value of dielectric constant (ε′ = 1823 at 100 Hz, ε′ = 122 at 1 MHz) with low dielectric loss (tanδ = 4.83 at 100 Hz) is obtained for composite with 40 wt% of GO content. The composite having 20 wt% of GO content has the lowest leakage current density (J = 4.99 × 10−7 A/cm2 at an applied electric field of 25 V/cm). The impedance study indicates the enhancement in charge transfer resistance in composites with the introduction of GO. The saturation magnetization (Ms) drops gradually from Ms = 38.28 emu/g for 0 wt% of GO to Ms = 24.10 emu/g for 30 wt% of GO and then rises to Ms = 25.64 emu/g at 40 wt% of GO content. The studied composites show the characteristics of a soft magnetic state with small values of coercivity (Hc ≤ 50 Oe). The findings reveal the exciting potential of synthesized composites for energy storage and magnetically tunable electronic devices.

Impact of composition ratio on the structure and optical properties of (1 – x)MnFe2O4/(x)ZnMn2O4 nanocomposite

(1 – x)MnFe2O4 (MFO)/xZnMn2O4 (ZMO) (x = 0, 0.2, 0.5, 0.8, and 1.0) nanocomposite samples were prepared using co-precipitation procedure. The phase percentage, cell parameters, and crystallite size of MFO and ZMO phases in each nanocomposite sample were calculated using Rietveld refinement procedure. The x-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy techniques established the variation in the lattice parameters of each phase are due to permutation of all cations among the octahedral and tetrahedral sites of MFO and ZMO. The different oxidation states of different ions in all samples were determined using x-ray photoelectron spectroscopy (XPS) technique. The variation in absorbance of the nanocomposite samples with composition parameter (x) is dependent on the wavelength region. The optical bandgap of the nanocomposite samples is decreased as the content of ZMO phase increased. The effect of alloying on the refractive index, extinction coefficient, dielectric constant, optical conductivity, and the nonlinear optical behaviors of all samples were studied in detail. The nanocomposite sample x = 0.5 disclosed upgraded optical parameters with the highest refractive index, optical conductivity, and PL intensity, which nominate it to be functional in various application fields.

Heterostructure coal-bearing strata kaolinite/MnFe2O4 composite for activation of peroxydisulfate to efficiently degrade chlortetracycline hydrochloride

The excessive discharge of the antibiotic chlortetracycline hydrochloride (CTC·HCl) directly threatens human life and health. Different from previous studies on MnFe2O4 (MFO) combined with bulk BT or disc-shaped DE in the treatment of antibiotic wastewater, in this study, layered coal-bearing strata kaolinite (CK) was used as a carrier to prepare MnFe2O4/coal-bearing strata kaolinite (MFO/CK) catalyst, and used to evaluate the effect of activated peroxodisulfate (PDS) in the removal of CTC·HCl in wastewater under visible light. Compared with MFO and CK, the specific surface area of MnFe2O4/coal-bearing strata kaolinite-40% (MFO/CK-40%) was significantly increased, the reactive sites increased, and the PDS activation and CTC·HCl degradation were better. After 60 min of reaction under visible light, the removal rate of CTC·HCl can reach 85.1%. In addition, the influence of various factors on the degradation of CTC·HCl was investigated. It is concluded that the most effective removal of CTC·HCl occurs when there is an additional 25 mg of MFO/CK-40%, the concentration of CTC·HCl is 50 mg/L, pH= 4, and PDS is 1.5 mL. Then, through electron spin resonance and radical trapping experiments, it was determined that h+ and ·O2− were the main active species for removing CTC·HCl. The mechanism of CTC·HCl degradation by the MFO/CK-40%/PDS/Vis system was discussed. Finally, the stability and reusability of the MFO/CK-40% composite material were tested. After 3 cycles of experiments, the removal rate of CTC·HCl is still more than 70%, indicating that the MFO/CK-40% composite material has good stability and catalytic activity. Therefore, the MFO/CK catalyst can be used as a new and efficient PDS activator, which is widely used in the photocatalytic degradation of organic matter in wastewater. Data AvailabilityNot applicable.

Constructing magnetically separable manganese-based spinel ferrite from spent ternary lithium-ion batteries for efficient degradation of bisphenol A via peroxymonosulfate activation

A magnetically separable manganese-based spinel ferrite (MFO-LIBs) is synthesized using spent ternary lithium-ion batteries (LIBs) for the first time. The ferrite is used to activate peroxymonosulfate (PMS) for the degradation of bisphenol A (BPA), thus meeting the strategy of “treating waste with waste.” Surprisingly, its degradation activity was 2.8 times that of pure MnFe2O4 (MFO). The characterization of the structure and morphology confirmed that the metals (e.g., Ni and Co) in spent ternary LIBs are doped into MFO, leading to MFO-LIBs with a larger specific surface area (1.3 times that of MFO) and a higher ratio of Mn(II)/Mn(III) (1.4 times that of MFO) and Fe(II)/Fe(III) (1.3 times that of MFO). Electron paramagnetic resonance and quenching experiments confirmed that surface-bound SO4∙-, surface-bound ∙OH, O2∙- and 1O2 are the main reactive oxygen species (ROS) in BPA degradation. Simultaneously, the improved degradation activity of the MFO-LIBs/PMS system can be ascribed to the increase in the number of ROS rather than the change in ROS types. Its outstanding performance can be maintained despite the high-salinity conditions (e.g., Cl-, HCO3- and H2PO4-), high content of humic acid and alkaline conditions. MFO-LIBs can be easily separated in the presence of an external magnetic field and has excellent universality (toward bisphenol F, 2,4-dichlorophenol and 2,4,6-trichlorophenol) and regeneration ability. More importantly, the cost of BPA degradation in the MFO-LIBs/PMS system is much lower than that of the related spinel ferrite activator/PMS systems (e.g., CoFe2O4/PMS and MnFe2O4/PMS systems).

Manganese ferrite nanoparticles enhanced biohydrogen production from mesophilic and thermophilic dark fermentation

In this work, Manganese ferrite nanoparticles (MnFe 2O4 NPs) were synthesized, and their potential to increase the biohydrogen (bio-H2) yield of glucose in mesophilic and thermophilic fermentations was evaluated. Material characterization showed that the MnFe 2O4 NPs were perfectly synthesized, with a specific surface area of 43.97 m2g−1. Both mesophilic and thermophilic fermentation obtained the highest bio-H2 yields of 272.7 and 183.4 mL H2/g glucose in the 400 mg/L MnFe 2O4 NPs group, which values were increased by 40.1% and 131.9% (37 °C and 55 °C), respectively, compared to their control groups. Soluble microbial products (SMPs) showed that MnFe 2O4 NPs enhanced the butyrate pathway. Three-dimensional fluorescence spectroscopy analysis showed that MnFe 2O4 NPs increased the extracellular polymer content of anaerobic sludge. The results showed that MnFe 2O4 NPs distinctly increased the abundance of Clostridium_sensu_stricto 1 (39.49%) in the microbial community during mesophilic fermentation and improved the abundance of the dominant bacteria Clostridium_sensu_stricto_7 (25.59%) and Longlinea (21.36%) during thermophilic fermentation. Real-time PCR analysis showed that hydrogenase gene (hycl) expression increased exponentially after the addition of MnFe 2O4 NPs, and increasing the fermentation temperature improved the hydrogenase activity. We found that MnFe 2O4 NPs promoted to bio-H2 production in both mesophilic and thermophilic fermentation, and it contributed more significantly to thermophilic fermentation than mesophilic fermentation.

Calcination-Free Synthesis of Well-Dispersed and Sub-10 nm Spinel Ferrite Nanoparticles as High-Performance Anode Materials for Lithium-Ion Batteries: A Case Study of CoFe2 O4.

Spinel ferrites are promising anode materials for lithium-ion batteries (LIBs) owing to their high theoretical specific capacities. However, their practical application is impeded by inherent low conductivity and severe volume expansion, which can be surpassed by increasing the surface-to-volume ratio of nanoparticles. Currently, most methods produce spinel ferrite nanoparticles with large size and severe aggregation, degrading their electrochemical performance. In this study, a low-temperature aminolytic route was designed to synthesize sub-10 nm CoFe2 O4 nanoparticles with good dispersion through carefully exploiting the reaction of acetates and oleylamine. The performance of CoFe2 O4 nanoparticles obtained by a traditional co-precipitation method was also investigated for comparison. This work demonstrates that CoFe2 O4 nanoparticles synthesized by the aminolytic route are promising as anode materials for LIBs. Besides, this method can be extended to design other spinel ferrites for energy storage devices with superior performance by simply changing the starting material, such as MnFe2 O4 , MgFe2 O4 , ZnFe2 O4 , and so on.

Multi-layered nano-hollow spheres for efficient electromagnetic wave absorption

Ferrite nano-hollow spheres (NHS) are of great significance to improve electromagnetic (EM) wave absorption performance. Herein, the deposition of dielectric SiO2 and ferrimagnetic CoFe2O4 (CFO) layers on MnFe2O4 (MnFO) NHS are found as an effective strategy to enhance EM wave attenuation. EM wave absorption properties of as-synthesized bare and bi-layered samples are investigated within a widely-used frequency range of 1–17 GHz. MnFO@CFO bi-layered NHSs exhibit an excellent reflection loss (RL) of −47.0 dB at only 20 wt% filler content with an effective broad bandwidth (BW) of ∼2.2 GHz (frequency region for RL < −10 dB). The attenuation constant is observed to increase from 191.6 Np m−1 to 457.8 Np m−1 for bare MnFO and MnFO@CFO NHSs respectively. Larger interfacial area, additional pairs of dipole, higher magnetic anisotropy, internal reflections and scattering from NHSs are responsible for superior absorption properties of MnFO@CFO NHSs. Moreover, the best impedance matching, ∣Z in /Z 0 ∣ ∼ 1, promotes the optimum RL in MnFO@CFO at 5.96 GHz. MnFO@SiO2 bi-layered NHSs result in a sufficiently high RL ∼ −30.0 dB with a composite absorber of a thickness of only 3 mm. Analysis from the λ/4 model for best matching thickness (t m ) displays a good agreement between experimental and simulated t m values. This study demonstrates optimized MnFO@CFO NHS as a highly promising low-cost and lightweight EM wave absorber suitable for practical high-frequency applications.

Rational construction of N,S-doped carbon wrapped MnFe2O4 nanospheres with copious oxygen deficiency as extremely efficient and robust electrocatalyst for urea electrocatalysis

Here, we fabricated N,S-Carbon (NSC) enfolded MnFe2O4 (MFO) nanospheres with abundant oxygen defects (OV), exploited as brilliant electrocatalyst for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). This typical nanoarchitecture possesses many characteristic compensations, (i) incorporation of OV in MFO to moderate the electronic arrangement for enhancing the electrons mobility and offering additional space for electrocatalysis and rapid absorption/diffusion of ions, (ii) homogeneously dispersed MFO nanospheres with great number of active sites and excellent catalytic activity, (iii) robust interaction between NSC and MFO ensuring the longstanding electrochemical stability, which are favorable to enhancing the kinetics of urea electrocatalysis. Electrochemical measurements proved NSC-MFO possesses outstanding UOR activity that shows a low potential of 1.42 V to attain 50 mA/cm2, too NSC-MFO contributes to excellent HER activity with low overpotential of 0.192 V to attain 50 mA/cm2. The excellent UOR performance of NSC-MFO authenticates could be wonderful applicant to replace OER to lower the cell potential thus decrease consumption of electrical energy for hydrogen-gas generation. As a proof of concept, overall urea splitting has been done with NSC-MFO as both cathode and anode, as-fabricated urea electrolytic cell offered 10 mA/cm2 at the cell voltage of 1.43 V with good durability for 15 h, displaying its potential practicability for energy-saving hydrogen making.

Mesoporous Composite Networks of Linked MnFe2O4 and ZnFe2O4 Nanoparticles as Efficient Photocatalysts for the Reduction of Cr(VI)

Semiconductor photocatalysis has recently emerged as an effective and eco-friendly approach that could meet the stringent requirements for sustainable environmental remediation. To this end, the fabrication of novel photocatalysts with unique electrochemical properties and high catalytic efficiency is of utmost importance and requires adequate attention. In this work, dual component mesoporous frameworks of spinel ferrite ZnFe2O4 (ZFO) and MnFe2O4 (MFO) nanoparticles are reported as efficient photocatalysts for detoxification of hexavalent chromium (Cr(VI)) and organic pollutants. The as-prepared materials, which are synthesized via a polymer-templated aggregating self-assembly method, consist of a continuous network of linked nanoparticles (ca. 6–7 nm) and exhibit large surface area (up to 91 m2 g−1) arising from interstitial voids between the nanoparticles, according to electron microscopy and N2 physisorption measurements. By tuning the composition, MFO-ZFO composite catalyst containing 6 wt.% MFO attains excellent photocatalytic Cr(VI) reduction activity in the presence of phenol. In-depth studies with UV-visible absorption, electrochemical and photoelectrochemical measurements show that the performance enhancement of this catalyst predominantly arises from the suitable band edge positions of constituent nanoparticles that efficiently separates and transports the charge carriers through the interface of the ZFO/MFO junctions. Besides, the open pore structure and large surface area of these ensembled networks also boost the reaction kinetics. The remarkable activity and durability of the MFO-ZFO heterostructures implies the great possibility of implementing these new nanocomposite catalysts into a realistic Cr(VI) detoxification of contaminated wastewater.

Thermal, microstructural and magnetic properties of manganese substitution cobalt ferrite prepared via co-precipitation method

Manganese-substituted cobalt nano-ferrites, Co(1−x)Mn(x)Fe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized using chemical co-precipitation method. Physical properties of Co(1−x)Mn(x)Fe2O4 nano-ferrites were then characterized using thermal gravimetric—differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrometer, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). TGA/DTA study indicates that the thermal stability of the prepared manganese doped cobalt ferrite nanoparticles. X-ray diffraction patterns of all the prepared ferrite samples show good in quality, pure nanosized, single-phased cubical spinel structures, with ferromagnetic behavior. We demonstrated that the expansion of lattice constant (a) and crystallite size (D) induced by manganese substituted of cobalt ferrites exerted remarkable effects on its structural and magnetic properties. The lattice constant (a) and crystallite size (D) increase with increasing manganese substituted cobalt ferrites. Williamson–Hall (W–H) method was used to evaluate the crystallite size and lattice strain of the Co(1−x) Mn(x)Fe2O4 nanoparticles samples by peak broadening. The calculated crystal size of Co(1−x) Mn(x)Fe2O4 nanoparticles on the W–H plots were highly intercorrelated with the HR-TEM and results of Scherrer Deby equation. The other physical parameters, such as X-ray density, hopping length, ionic radius, bond length, tetrahedral edge, octahedral edge, and unshared octahedral edge values were estimated from the highest intensity peak (311) of X-ray diffraction. The Fourier transform infrared (FT-IR) spectrometer of the Co–Mn ferrite nanoparticles systems were recorded in the frequency range of 200–1000 cm−1. FT-IR spectra show the two fundamental absorption bands of interstitial sub-lattice sites (M–O). The high absorption band (ν1) and the low absorption band (ν2) corresponds to the tetrahedral [A] and octahedral (B) sites, respectively, confirming the formation of single cubic spinel ferrite lattice system. The TEM results show that the ferrite nanoparticles have a nearly spherical shape with some agglomerations. From the analysis of VSM, the values of saturation magnetization (Ms) increases from 31.46 to 37.16 emu/g, then decreases with increasing Mn2+ ions substitution in the Co-ferrite system. The coercivity of the Mn2+ ions substituted cobalt ferrites increases up to x = 0.6 followed by a decrease. The optimized magnetic parameters suggest that the material with composition Co0.6Mn0.4Fe2O4 may be suitable for longitudinal magnetic recording media and other various technological applications.