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This study investigates the electrical transport properties of gadolinium-doped cobalt ferrite (Gd-doped CoFe2O4) which is prepared by a high-temperature solid-state synthesis method. The study mainly focuses on the sensitivity of the material for different in temperature and frequency, exploring its potential application as a negative temperature coefficient (NTC) thermistor. X-ray diffraction analysis is used to verify the crystal structure and phase purity. Scanning electron microscopy (SEM) was used to characterize the surface microstructure. Particle size distribution analysis revealed that increasing the gadolinium (Gd) doping concentration has resulted in a decrease in average grain size. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the chemical composition of the Gd-doped cobalt ferrite (CoFe2O4) compounds. The dielectric properties of these compounds were examined as functions of temperature and frequency. The impact of grains on the overall electrical response of all the prepared samples was observed by analyzing the Nyquist (Cole-Cole) plots at various temperatures. The NTCR characteristics of the prepared materials were determined from the temperature response of DC conductivity. The grain resistance at various temperatures is used to evaluate the thermistor parameters by considering the strong temperature dependence of resistivity. This indicates the potential use of grain resistance in thermistor-based devices. The frequency-dependent conductivity agrees well with Jonscher's proposed universal power law. Temperature-dependent spectroscopic plots of the conductivity provide the activation energy, which exhibits that the charge carriers influence the transport characteristics of the compound. [ABSTRACT FROM AUTHOR]

This study investigates the electrical transport properties of gadolinium-doped cobalt ferrite (Gd-doped CoFe2O4) which is prepared by a high-temperature solid-state synthesis method. The study mainly focuses on the sensitivity of the material for different in temperature and frequency, exploring its potential application as a negative temperature coefficient (NTC) thermistor. X-ray diffraction analysis is used to verify the crystal structure and phase purity. Scanning electron microscopy (SEM) was used to characterize the surface microstructure. Particle size distribution analysis revealed that increasing the gadolinium (Gd) doping concentration has resulted in a decrease in average grain size. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the chemical composition of the Gd-doped cobalt ferrite (CoFe2O4) compounds. The dielectric properties of these compounds were examined as functions of temperature and frequency. The impact of grains on the overall electrical response of all the prepared samples was observed by analyzing the Nyquist (Cole-Cole) plots at various temperatures. The NTCR characteristics of the prepared materials were determined from the temperature response of DC conductivity. The grain resistance at various temperatures is used to evaluate the thermistor parameters by considering the strong temperature dependence of resistivity. This indicates the potential use of grain resistance in thermistor-based devices. The frequency-dependent conductivity agrees well with Jonscher's proposed universal power law. Temperature-dependent spectroscopic plots of the conductivity provide the activation energy, which exhibits that the charge carriers influence the transport characteristics of the compound. [ABSTRACT FROM AUTHOR]

Magnetic ferrite nanoparticles have a broad application in wastewater treatment, and the interest in applying these particles specifically in waste treatment is growing. However, the gap in understanding how ferrite properties that are controllable through synthesis methods affect wastewater treatment efficiency needs to be better explained. In this review, we assess the analysis of the most impactful publications to highlight the controllable ferrite nanoparticles' properties through the different synthesis methods and their parameters connected to wastewater treatment efficiency. For a long time, ferrite nanoparticles were seen as adsorbents suitable for physically removing pollutants, but recent studies show that these nanostructures could be suitable for UV and visible light-induced photocatalytic decomposition of contaminants. [ABSTRACT FROM AUTHOR]

This paper presents the deposition of manganese-doped cobalt ferrite (CoMnF) thin films on FTO substrates using spray pyrolysis. Optimization of the crucial growth parameters, along with annealing at 450°C for 2 hours, has led to a single-phase cubic spinel structure without any extraneous peaks confirmed by X-ray diffraction. The films have interplanar distances between 4.896 to 1.484 Å, crystallite sizes are small: FWHM: 0.338° to 0.497°, and the lattice constant is 8.418 Å. FTIR has identified a peak at 431 cm-1, with implications for the presence of the ferrite phase due to the existence of octahedral metal-oxygen stretching. The UV-Vis spectra reveal strong absorption at 215 nm and 347 nm. The direct bandgap has been found to be 5.6 eV. Raman vibrational modes are affected due to Mn doping. These Mn-doped Co-ferrite thin films have properties that are well suited for application in supercapacitors, sensors, and energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract Purpose This research aims to explore the transmission of seismic surface waves through a two magneto-strictive materials i.e. cobalt ferrite and Terfenol-D when embedded in a plate-substrate configuration with non-ideal interface. The study focuses on understanding the impact of width of the plates, imperfect parameter, heterogeneity parameter on both the materials cobalt ferrite and Terfenol-D under magnetically open and short conditions. Methodology To achieve this, the study employs a variable-separable technique following Direct Sturm-Liouville method and appropriate boundary conditions to derive frequency relations for both magnetically open and short circuit scenarios. Numerical simulations are conducted to investigate the effects of width of the plates, imperfect parameter, heterogeneity parameter on both the materials cobalt ferrite and Terfenol-D under magnetically open and short conditions. Findings The research findings indicate that the phase velocity is increasing more in Terfenol-D as compared to Cobalt ferrite, either the case magnetically open or closed. Graphical comparisons highlight the impact of width plates, imperfect parameter, heterogeneity parameter on the characteristics on wave propagation clearly. Research limitations The study is confined to linear wave propagation and does not consider nonlinear effects. Additionally, the analysis is based on idealized material properties and interface conditions. Practical implications The results of this research can contribute to the design and optimization of sensors, energy harvesters, and wave manipulation devices utilizing piezomagnetic materials. Understanding the behaviour of surface waves in these structures is crucial for their effective application. Originality This study offers a comprehensive analysis of surface wave propagation in two different types of piezomagnetic composite structure by considering heterogeneity and interface conditions. The comparative study of different piezomagnetic models and the incorporation of heterogeneity and interface conditions contribute to the originality of the research.

This study details the nickel-substituted cobalt ferrite nanoparticle employing natural fine sediment (NiCFO-fs) annealing temperature dependency of crystalline and magnetic characteristics. The NiCFO-fs nanoparticles were prepared by the coprecipitation method with varying annealing temperatures (200-500°C with increment of 100°C for five hours). As a comparison, Ni-CFO was also synthesized using pure analytical chemicals (NiCFO-pa). The XRD results showed that the whole Ni-CFO nanoparticles established an inverse spinel face center cubic (fcc) order according to space group Fd-3m for both NiCFO-fs and NiCFO-pa. There was no additional peak, indicating that Ni2+ cations successfully substituted in cobalt ferrite nanoparticles. In case of NiCFO-fs nanoparticle samples, a crystallite size (D) decreased with the increasing annealing temperature (Ta), namely 45.72 nm, 37.35 nm, 25.95 nm, and 20.51 nm. In contrast to NiCFO-pa, the D increased with the increase of the Ta, i.e., 19.67 nm, 20.74 nm, 21.99 nm, and 23.33 nm. Meanwhile, FTIR results showed the presence of metal-oxygen bonds at 551-586 cm-1 and 384-391 cm-1 at tetrahedral (k1) and the octahedral (k2) sites for both NiCFO-fs and NiCFO-pa nanoparticles samples. The VSM result showed that a narrow hysteresis curve was observed for the NiCFO-fs sample compared to NiCFO-pa. The NiCFO-fs nanoparticles owing the smallest coercive field (HC) of 79.5 Oe were attained for the Ta of 300°C. In case of NiCFO-fs samples, magnetization saturation (MS) decreased with the increase of the Ta in contrast to NiCFO-pa samples. Here, the redistribution of two and three plus ions in the sub-lattice k1 and k2 locations should be encouraged by the Jahn-Teller phenomenon through strain-induced magnetism. The findings of the antibacterial test indicated that the potential of NiCFO based on natural materials (fine sediment) was higher than that of NiCFO based on pure analytical chemicals. This result was also supported by the emergence of ZOI magnitudes for all NiCFO-fs materials compared to NiCFO-pa that was only at Ta = 300°C.

This study aimed to model the thermomechanical vibration behavior of sandwich nanoplates consisting of a foam or solid core layer and smart surface layers. The sandwich plate's mechanical behavior is analyzed using the nano-size effect, nonlocal strain gradient theory, and sinusoidal higher-order plate theory. Hamilton's principle is employed to derive the equations of motion, which are subsequently solved using the Navier method. The impacts of temperature, foam structure, foam void ratio, smart materials, and the external electric and magnetic potentials applied to the surface layers on the thermomechanical behavior of a sandwich plate have been analyzed. [ABSTRACT FROM AUTHOR]

Cobalt ferrite, a prominent magnetic nanomaterial, has attracted huge interest for its exceptional physical and chemical properties. These characteristics make it an ideal candidate for a myriad of advanced applications. Particularly, the properties of cobalt ferrite can be finely tuned by manipulating the cation distribution within its structure. This study explores the impact of substituting Fe3+ ions with rare earth (RE3+) ions—specifically Lanthanum (La), Europium (Eu), Cerium (Ce), and Gadolinium (Gd)—whose ionic radii are larger than that of Fe3+. This replacement, even in minimal amounts, significantly affects the physical and chemical properties of cobalt ferrite, primarily due to induced structural distortions and lattice strain. In the present work, we have doped the ferrite crystal lattice with these rare earth (RE) elements using the sol–gel method. The structural and magnetic properties of the resulting samples are analyzed by different characterization techniques, including powder X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) complemented by Energy Dispersive X-ray Spectroscopy (EDX), Raman spectroscopy, and Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA). Additionally, the magnetic properties of the synthesized nanomaterials were evaluated using a Vibrating Sample Magnetometer (VSM). This research reveals a systematic decrease in saturation magnetization values, with pure CFO (CoFe2O4) displaying approximately 74.96 emu/g, and varying reductions observed upon substitution with rare earth (RE) metal ions (La3+, Ce3+, Eu3+, Gd3+; x = 0.0 and 0.1). Furthermore, the introduction of rare earth (La, Gd) dopants correlates with an elevated coercivity (Hc) value, emphasizing the influence on crystal unit symmetry and magneto-crystalline anisotropy. [ABSTRACT FROM AUTHOR]

Water pollution is an alarming and critical environmental challenge that demands immediate attention. In addition to this, the world is also facing an energy crisis of ever-increasing proportions. Managing these issues through a sustainable approach is the need of the hour. In this context, microbial fuel cell (MFC) technology, with its dual capability to treat wastewater with simultaneous power generation, is gaining recognition as a sustainable solution. The current study was designed to evaluate the impact of a modified MFC anode, i.e., CoFe2O4@CF, Nb2C-MXene@CF, and CoFe2O4/Nb2C-MXene@CF, on the performance of MFC technology. A hydrothermal technique was used to synthesize CoFe2O4 and Nb2C-MXene, followed by characterization using XRD, SEM, and EDX tools. The results demonstrated that CoFe2O4/Nb2C-MXene@CF significantly enhanced the working performance of a MFC as compared to CoFe2O4@CF and Nb2C-MXene@CF. The MFC with this configuration produces a stable voltage (699.8 mV), coulombic efficiency (23.8%), COD removal (84%), and power density (394.272 mWm−2), with corresponding current density (888 mAm−2). These improvements were possibly due to the excellent electrocatalytic activity and strong biocompatibility of the modifier. Conclusively, the CoFe2O4/Nb2C-MXene composite is ascertained to be an emphatic anode material for MFCs with superior characteristics. [ABSTRACT FROM AUTHOR]

Laser ablation was used to successfully fabricate multiferroic bilayer thin films, composed of BaTiO3 (BTO) and CoFe2O4 (CFO), on highly doped (100) Si substrates. This study investigates the influence of BaTiO3 layer thickness (50–220 nm) on the films' structural, magnetic, and dielectric properties. The dense, polycrystalline films exhibited a tetragonal BaTiO3 phase and a cubic spinel CoFe2O4 layer. Structural analysis revealed compression of the CoFe2O4 unit cell along the growth direction, while the BaTiO3 layer showed a tetragonal distortion, more pronounced in thinner BTO layers. These strain effects, attributed to the mechanical interaction between both layers, induced strain-dependent wasp-waisted behavior in the films' magnetic hysteresis cycles. The strain effects gradually relaxed with increasing BaTiO3 thickness. Raman spectroscopy and second harmonic generation studies confirmed BTO's non-centrosymmetric ferroelectric structure at room temperature. The displayed dielectric permittivity dispersion was modeled using the Havriliak–Negami function combined with a conductivity term. This analysis yielded relaxation times, DC conductivities, and activation energies. The observed BTO relaxation time behavior, indicative of small-polaron transport, changed significantly at the BTO ferroelectric Curie temperature (Tc), presenting activation energies Eτ in the 0.1–0.3 eV range for T < Tc and Eτ > 0.3 eV for T > Tc. The BTO thickness-dependent Tc behavior exhibited critical exponents ν ~ 0.82 consistent with the 3D random Ising universality class, suggesting local disorder and inhomogeneities in the films. This was attributed to the composite structure of BTO grains, comprising an inner bulk-like structure, a gradient strained layer, and a disordered surface layer. DC conductivity analysis indicated that CoFe2O4 conduction primarily occurred through hopping in octahedral sites. These findings provide crucial insights into the dynamic dielectric behavior of multiferroic bilayer thin films at the nanoscale, enhancing their potential for application in emerging Si electronics-compatible magneto-electric technologies. [ABSTRACT FROM AUTHOR]

Graphene oxide–cobalt ferrite magnetic nanocomposite (M-GOC) was efficiently synthesised by microwave-assisted method for water remediation. The graphene oxide (GO) was synthesized by improved Hummers’ method, while cobalt ferrite (CoFe2O4) was synthesized by microwave-assisted combustion method. X-ray diffractograms indicated high phase-pure M-GOC with an average crystallite size of 18.5 nm. An enhancement in the absorbance was observed in the range of 220–280 nm due to the presence of additional π–π* transition of aromatic C–C bonds of GO. Appearance of a peak around 584 cm−1 corresponds to the stretching vibration of Co–O bond. Corrugated GO sheets were observed in SEM and HRTEM images with agglomerated spherical CoFe2O4 nanoparticles intercalated between the GO sheets. A particle size distribution curve was plotted that indicated an average particle size of ~11 nm of the CoFe2O4 nanoparticles. Raman spectra of GO confirmed the synthesis of pure GO sheets. Vibrating sample magnetometer was employed to investigate the magnetic behaviour of M-GOC, which showed a Mr/Ms ratio of 0.278. The adsorption study was performed, in which M-GOC nanocomposite exhibited an excellent adsorption capacity of 2229.9 mg g−1 for heavy metal i.e., cadmium ions (Cd+2). [ABSTRACT FROM AUTHOR]

The structure, magnetic properties and ferromagnetic resonance curves of cobalt ferrite particles synthesized by chemical coprecipitation technique have been studied. The possibility of resonant heating of powder in a magnetic anisotropy field of particles is shown, which can find application in medicine for magnetic hyperthermia. [ABSTRACT FROM AUTHOR]

The change in the behavior of pristine cobalt ferrite on doping it with rare-earth (RE) metal ions has been investigated. The CoFe2-xDyxO4 (where x = 0–0.1, with stepsize of 0.02) nanomaterials were synthesized by the co-precipitation method and corresponding morphological, structural, optical, and magnetic properties were observed. The x-ray diffraction (XRD) spectra revealed that all the prepared samples show a crystalline nature and that the crystallite size reduces with increasing dysprosium (Dy) concentration from 21 to 9 nm for x = 0.02 to x = 0.1. The Fourier-transform infrared spectroscopy (FTIR) spectra in the 4000–400 cm−1 range supported the material formation. Diffused reflectance spectroscopy (DRS) was used for the energy bandgap calculation. Field-emission scanning electron microscopy (FESEM)–energy dispersive x-ray spectroscopy (EDAX) spectra showed the surface morphology and elemental composition of the materials and no peaks corresponding to other elements were observed. Room-temperature Vibrating sample magnetometer (VSM) studies at a field of 7 T revealed that the sample with x = 0.02 had the highest value of saturation magnetization at 77.39 emu/g, which is even greater than the CoFe2O4 sample, while the sample composition x = 0.1 had the least saturation magnetization of 36.41 emu/g. This reduction was brought on by the lower magnetic interactions between the RE3+ and Fe3+ ions. Such materials can have applications in optoelectronic, magnetic hyperthermia, and high-frequency devices. [ABSTRACT FROM AUTHOR]

This research paper investigates new and first insights into the magnetic and magnetocaloric properties of one-dimensional (1D) cobalt ferrite CoFe2O4 (CFO) nanofibers (NFs) fabricated using a sol–gel-based electrospinning technique, focusing in particular on their behavior at low temperatures for specific applications. The microstructural, structural, magnetic, and magnetocaloric properties of the calcined CFO NFs were explored. The microstructure of the NFs, with an average diameter of 210 nm, was examined by scanning and transmission electron microscopy (SEM, TEM). The x-ray diffraction (XRD) of the CFO NFs showed a pure cubic close-packed (ccp) spinel crystalline structure with the Fd 3 ¯ m space group. The Raman spectroscopic studies further confirm the cubic inverse spinel phase. The magnetic properties were explored as a function of temperature, ranging from 10 K to 300 K, and ferromagnetic behavior was observed with the highest saturation magnetization of 75.87 emu/g and coercivity of 723 Oe at room temperature. The variation of the magnetic entropy was measured indirectly using the Maxwell approach with an increasing magnetic field. A maximum of Δ S = 1.71 J/K was reached around 32 K. At 180 K, the associated adiabatic temperature change, ΔTmax, was 0.93 K, with a large RCP value of 7.58 J/kg, which is reasonably high for the corresponding nanoparticles (NPs). This work suggests that 1D CFO NFs offer a promising route for the production of nanostructured magnetic materials, potentially impacting various electronic and electromagnetic device applications at low temperatures. [ABSTRACT FROM AUTHOR]

The crystal structure and vibrational spectra of CoFe2O4 ferrite were studied using X-ray diffraction and Raman spectroscopy over a pressure range of 0–35GPa. A structural phase transition from the cubic Fd3̄m phase to the post-spinel orthorhombic Bbmm phase occurs at a pressure of approximately 23GPa through a two-phase region. Pressure-induced changes in the structural parameters, lattice distortion, and vibrational modes of the studied ferrite were investigated in detail. Lattice parameters, bond lengths, compressibility, and bulk modulus for both the cubic and orthorhombic phases of CoFe2O4 were determined. [ABSTRACT FROM AUTHOR]

There is a strong demand for noble metal-free durable catalysts to facilitate the advancement of clean, sustainable energy technologies and to replace energy equipment reliant on fossil fuels. In this study, metal-organic framework (MOF)-derived CoFe 2 O 4 (CFO) nanoparticle-embedded electrospun carbon nanofibers (CNFs) were synthesized. Nanofibers were calcined at three different temperatures to obtain optimum electrocatalytic performance in oxygen evolution reaction (OER). Nanofibers annealed at 800 °C (CFO@CNFs 800) displayed a reduced overpotential of 300 mV while maintaining a steady current density of 10 mA cm−2. CFO@CNFs 800 demonstrated Tafel slope 42 mV dec−1 with excellent long-term stability up to 48 h. The synergistic effect of the redox activity of CFO coupled with the high surface area and conductivity of carbon nanofibers is responsible for enhanced OER performance. [Display omitted] • Developed CFO carbon nanofibers using hydrothermal and electrospinning techniques. • Annealed nanofibers at 600 °C, 700 °C, and 800 °C, labeled as CFO@CNFs 600, 700, and 800. • CFO@CNFs 800 showed a low overpotential of 307 mV at 10 mA cm−2. • Measured charge transfer resistance (Rct) of 1.5 Ω/cm2 and Tafel slope of 42 mV dec⁻1 for CFO@CNFs 800. • CFO@CNFs 800 demonstrated excellent stability over 48 h, with improved OER performance due to the synergistic effect of iron, cobalt, and the conductivity of the MOFs and nanofibers. [ABSTRACT FROM AUTHOR]

The article presents a comprehensive investigation of the crystal structure, impedance spectra, magnetic, magnetodielectric, and magnetoresistive properties of (1- x)CoFe 2 O 4 – x PbTiO 3 composites with varying concentrations (х = 0, 0.2, 0.4, and 0.6). The study also examines the effects of applying a uniaxial pressure of 1 GPa to the synthesized powders using Bridgman anvils. Our findings reveal that the synthesis of these composites results in the formation of an additional phase, lead hexaferrite PbFe 12 O 19 , which exhibits multiferroic properties. Additionally, the coherent scattering region of the components is significantly reduced after mechanical activation. Notably, the real part of the resistivity ρ ′(ω) of nanostructured CoFe 2 O 4 ceramics increases eightfold at T = 240 °C. The composites demonstrate significant magnetoresistance at room temperature, reaching up to 250 %. The study also reveals that the signs of the magnetodielectric MD (B) and magnetoresistive coefficient MR (B) vary with the frequency of the measuring field for certain concentrations. Using the first-order reversal curve (FORC) method, it was observed that after nanostructuring CoFe 2 O 4 through mechanical activation, the interaction field H u shifts from ± 0.6 kOe to ± 0.8 kOe, while the coercive field H c increases from 1.05 kOe to 5 kOe. Moreover, the two-dimensional FORC maps of the composites show increased complexity, due to the formation of additional magnetic phases. [ABSTRACT FROM AUTHOR]

Cobalt ferrite (CFO) nanoparticles (NPs) are highly promising for data storage, energy conversion, permanent magnets, and biomedical applications owing to their exceptional magnetic properties. However, the presence of phase impurities (particularly FeO and CoO) can severely degrade their magnetic properties, hindering their practical use. Here, we present a simple post‐synthesis oxidation approach to address this challenge. Our method involves the thermal decomposition of Fe−Co oleate followed by oxidation using trimethylamine N‐oxide. The results reveal the effective elimination of FeO and CoO impurities and the formation of spinel ferrite crystal structures post‐oxidation with no change in morphology or size. Magnetic measurements demonstrate a significant enhancement in magnetic properties (e. g., magnetic saturation, coercivity, and blocking temperature) in oxidized CFO NPs compared to the non‐oxidized counterparts, indicative of the recovered ferrimagnetic structure upon post‐synthesis oxidation. As expected, the restoration of the ferrimagnetic structure, resulting in improved magnetic anisotropy, led to decreased SAR values as the nanoparticles moved away from the optimal anisotropy range. The study underscores the necessity of post‐synthesis oxidation for ensuring phase purity and enhancing the magnetic properties of CFO NPs, irrespective of the synthesis method. This approach offers a promising route for producing highly functional magnetic nanoparticles for practical applications. [ABSTRACT FROM AUTHOR]

Global industrialization has led to a pressing concern of water pollution from refractory reactive dyes. Among Advanced oxidation processes, the Fenton photocatalyst, particularly cobalt ferrite (CoFe2O4), is gaining attention due to its advantages, including stability, visible light utilization, recyclability, cost-effectiveness, and light corrosion resistance. This study investigates the synthesis and application of cobalt ferrite magnetic nanoparticles (CFNs) as a Fenton-like catalyst for degrading Reactive Blue 19 (RB19) dye under UV irradiation. CFNs were characterized using XRD, SEM, and VSM techniques. The photo degradation of RB19 was assessed under various conditions, including catalyst dosage, oxidant amount, RB19 concentration, and pH. The maximum removal efficiency of RB19 was achieved as 97.3% for synthetic wastewater under the optimal conditions of pH 3, CoFe2O4 dosage (1.5 g/L), reaction time = 60 min, and H2O2 (80 mM) in the presence of UV radiation (18 W) at the ambient room temperature of 22 °C. The results revealed that the CFNs exhibited high stability, reusability, and catalytic activity. Moreover, the mineralization studies indicated significant removal rates for both RB19 and chemical oxygen demand (COD). The findings suggest the promising application of CFNs in advanced wastewater treatment processes. [ABSTRACT FROM AUTHOR]

A comparative study of cobalt ferrite (CoFe2O4) catalysts synthesized via three different methods is presented, aiming to evaluate their catalytic activities in poly(ethylene terephthalate) (PET) chemical depolymerization by glycolysis. The synthesized catalysts have been characterized by X-ray photoelectron spectroscopy, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and energy dispersive spectroscopy. The conversion of PET into bis(2-hydroxyethyl)terephthalate (BHET) monomer was examined using these cobalt ferrites. The BHET in the reaction mixture was analyzed by FTIR, HPLC, DSC, and TGA and results show the catalyst synthesized by coprecipitation demonstrates the highest BHET yield (95.4%) at a temperature of 200 °C and a pressure of 0.7 bar in 1 h with only 1.0 wt% loading. Hydrothermal synthesized CoFe2O4 and solvent-free synthesized CoFe2O4 both showed lower BHET yields. The catalytic performance of the coprecipitated CoFe2O4 catalyst was influenced by the presence of unintentionally trapped FeCl3 within the catalyst, which resulted in its enhanced activity. The CoFe2O4 catalyst from coprecipitation exhibited acceptable magnetic recoverability and reusability for four consecutive cycles, further highlighting its usefulness and sustainability. [ABSTRACT FROM AUTHOR]

Improving the efficiency of bifunctional electrocatalysts is a decisive challenge in the area of long‐lasting rechargeable zinc‐air batteries. Enhancing the catalysts' performance is crucial for advancing zinc‐air batteries. Transition‐metal oxides have emerged as promising non‐precious, noble‐metal‐free catalysts. Herein, a unique precursor directed approach is introduced for preparing a cobalt ferrite@nitrogen doped carbon nanohorns (CoFe2O4@N‐CNHs) nanohybrid catalyst in a single step annealing process involving stoichiometric amounts of single‐source cobalt and iron molecular precursors and carbon nanohorns (CNHs) under an argon/ammonia (Ar/NH3) atmosphere. This procedure enables a simultaneous CoFe2O4 ferrite synthesis and nitrogen functionalization of CNHs. The precious metal free nanohybrid CoFe2O4@N‐CNHs‐30% containing 30% of carbon presents an oxygen reduction reaction (ORR) half wave potential and onset potential comparable to the standard ORR catalyst 20% Pt/C. CoFe2O4@N‐CNHs‐30% also establishes superior oxygen evolution reaction (OER) performance with a low overpotential and a small Tafel slope than benchmark OER catalyst RuO2. Furthermore, the rechargeable zinc‐air battery with the CoFe2O4@N‐CNHs‐30% nanohybrid as air electrode demonstrates steadier and more durable charge–discharge cycles, and outstanding energy density relative to the state‐of‐the‐art 20% Pt/C‐RuO2 catalyst. [ABSTRACT FROM AUTHOR]

This study is an attempt to compare the hyperthermia and antimicrobial activity of three members of the family of spinel ferrite magnetic nanoparticles (XFe2O4, where X = Mg, Cu, and CO) MNPs. Spinell ferrite of MgFe2O4, CuFe2O4, and CoFe2O4 were prepared via sol–gel method. Structural and morphological shapes were investigated by different techniques X-ray diffraction X-ray powder diffractometer (XRD), Fourier transformed infrared spectroscopy (FTIR), and (Transmission electron microscope) TEM. Magnetic properties were examined by vibrating sample magnetometer (VSM). The in vitro test was conducted on cervical Hela cells using an MTT assay. Finally, the antimicrobial activity was tested on Staphylococcus aureus, Bacillus subtlus, and Escherichia coli using a clearing inhibition zone. XRD results confirmed the crystalline nature of MgFe2O4, CuFe2O4, and CoFe2O4. VSM results showed a high maximum saturation (Ms = 44.87 emu/g) of CuFe2O4 which is greater than that of CoFe2O4 and MgFe2O4 (18.221 and 18.669) emu/g, respectively. MTT assay revealed that high cell death was detected on Hela cells of CuFe2O4 compared to that of MgFe2O4 and CoFe2O4. The anti-microbial study showed that the prepared spinel magnetic nanoparticles possessed antimicrobial activity due to the release of Mg, Cu, Co, and Fe ions. Results showed that the CuFe2O4 could be a good spinel ferrite for medical application with antimicrobial activity and generate heat (hyperthermia, anti-cancer material). [ABSTRACT FROM AUTHOR]

The development of new catalytic systems based on cobalt and iron compounds for the production of oxygen-containing compounds is an urgent task of chemical technology. The purpose of this work is the synthesis of CoFe2O4 stabilized with polyvinylpyrrolidone (PVP), the study of the catalyst by physico-chemical research methods, and the determination of the effectiveness of the CoFe2O4/PVP catalyst in the phenol oxidation reaction. In this work, magnetic composites CoFe2O4 and CoFe2O4 stabilized with polyvinylpyrrolidone were synthesized by co-deposition. A comparison of the characteristics of the properties of the synthesized cobalt (II) ferrite (CoFe2O4) and the composite material CoFe2O4/PVP based on it is carried out. The obtained samples were examined using X-ray phase analysis (XRD), the Debye–Scherrer method, scanning electron microscopy (SEM), Mossbauer and IR Fourier spectroscopy, as well as thermogravimetric analysis (TGA). The textural properties were determined based on the analysis of nitrogen isotherms. The catalytic properties of the synthesized materials in the process of phenol oxidation in the presence of hydrogen peroxide are considered. The analysis of the reaction mixtures by HPLC obtained by the oxidation of phenol in the presence of a CoFe2O4/PVP catalyst showed a decrease in the concentration of phenol in the first 15 min of the process (by 55–60%), and then within 30 min, the concentration of phenol decreased to 21.83%. After 2 h of the process, the conversion of phenol was already more than 95%. The final sample after the reaction contained 28% hydroquinone and 50% benzoquinone. It was found that the synthesized magnetic composites exhibit catalytic activity in this process. [ABSTRACT FROM AUTHOR]

The present study focuses on the modification induced by 200 MeV Ag15+ and 100 MeV O7+ ion irradiations on the structural, surface morphological, and magnetic properties of radio frequency sputtered CoFe2O4 (CFO) thin films grown on SiO2/Si (100) substrates. X‐ray diffraction shows amorphization of the CFO thin films when irradiated with Ag ions and varies with fluences. This effect is absent in the case of O ion irradiated CFO films. These results are consistent with the measurements from the Raman spectroscopy, where the intensities of Eg and T2g modes are significantly reduced and further disappear in the high fluence. The surface morphology of the O ion irradiated films is dramatically different from the pristine and Ag ion irradiated films where the surfaces appear in nanopillars‐like patterns. The topography of the O ion irradiated films appears to be like hill and valley structures, the roughness first increases (from 10.11 to 24.39 nm). Then it decreases to 18.93 nm on further increasing ion fluence. The coercivity, remnant magnetization, and saturation magnetization increase upon irradiation at low fluence 5 × 1011 ions/cm2 for both the ion beams and then downturn with the increase of fluence 5 × 1012 ions/cm2. The changes in the magnetic and structural characteristics are ascribed to the defects induced by ion irradiation. These results are understood based on the structural and surface modifications induced by the electronic excitation of Ag and O ions. The study depicts that a controlled selection of ions and beam fluence can tailor the structure, morphology, and magnetic properties of ferrite films. [ABSTRACT FROM AUTHOR]