Metal Ferrites Research Articles

Augmented catalytic effect of nano‐bi‐transition metal ferrite NiZnFe2O4 for nano‐nitrotriazolone thermolysis

The present research aims to study the thermolysis behavior of nano‐nitrotriazolone (nNTO) with and with catalyst bi‐transition metal ferrite (NiZnFe2O4‐NZF). Synthesized NTO via consecutive reaction method was modified to nanosize by using solvent–antisolvent method, while co‐precipitation method was used for the preparation of ferrite. Their physico‐chemical characteristics have been investigated in detail by using X‐ray diffraction (XRD), field emission gun scanning electron microscope (FEG‐SEM), Fourier transform infrared (FTIR), Raman, and ultraviolet–visible (UV–vis) analytical techniques. The catalytic performance was studied briefly using simultaneous thermal analyses. The average crystalline size of NZF is found between 12 and 25 nm, while NTO and nNTO are found between 15 and 40 nm. The nNTO derived from NTO showed higher crystallinity and less agglomeration, while NZF has nanoparticles with polyhedral shape. The thermal results are depicted that this catalyst worked superior to enhance thermolysis of nNTO than its mixture with NTO and it was evaluated by the various kinetic model. The kinetic mean values revealed that nNTO + NZF activation energy decreased in the range of 100–150 kJ mol−1. According to the obtained results, such kind of catalyst has been used for the preparations of explosive energetic formulations that are widely applicable in rocketry development.

Synthesis and characterization of mixed ternary transition metal ferrite nanoparticles comprising cobalt, copper and binary cobalt–copper for high-performance supercapacitor applications

Metal ferrites have outstanding electrochemical characteristics owing to the numerous oxidation states of the metal ions, making them promising materials for addressing both sustainable energy conversion and storage and growing environmental issues. Therefore, three nanocrystallites transition metal ferrites, CoFe2O4, CuFe2O4 and Co/CuFe2O4, were synthesized using citrate precursors and used as electrode materials for supercapacitor applications. Mixed transition metal ferrite nanoparticles were characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM) complemented with energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Raman spectroscopy and thermal analysis (TGA). The findings illustrated the formation of a single-phase spinel ferrite as proved from XRD data. In addition, the particle shape and particle size obtained from TEM analysis revealed that the as-synthesised nanomaterial exhibited spherical shape with a size ranging from 30 to 50 nm. The result demonstrated that while using a three-electrode configuration, the electrochemical performance of the ferrite nanoparticles achieved a remarkable maximum specific capacitance of 893 Fg−1 at a scan rate of 5 mV s−1. At a current density of 1 Ag−1, Co–Cu ferrite exhibited outstanding cycling stability for 3000 cycles with 90% capacity retention. Based on the aforementioned data, it can be considered that the remarkable electrochemical performance of the Co–Cu ferrite nanocomposites can be considered as promising materials to be used for supercapacitor electrodes.

A facile synthesis of metal ferrites (MFe2O4, M = Co, Ni, Zn, Cu) as effective electrocatalysts toward electrochemical hydrogen evolution reaction

Developing low-cost, stable, and robust electrocatalysts for hydrogen evolution reaction (HER) is highly desirable for large-scale application. In this study, a highly efficient electrocatalysts of metal ferrites (MFe2O4, M = Co, Ni, Zn, Cu) with superior activity and durability are successfully fabricated on copper substrate through a facile co-precipitation method followed by doctor-blading deposition. The electrocatalytic performance of CoFe2O4, NiFe2O4, ZnFe2O4 and CuFe2O4 electrodes for hydrogen evolution reaction is studied in alkaline media using polarization curves and electrochemical impedance spectroscopy (EIS). Among them, CoFe2O4 presented the best electrocatalytic activities for HER with extremely low overpotentials of 270 mV (vs. RHE) at a current density of 10 mA cm−2 in 1 M KOH. The electrocatalytic activity of MFe2O4 (M = Co, Ni, Zn, Cu) for HER to generate current density of 10 mA cm−2 with low overpotential followed the order of CoFe2O4 > CuFe2O4 > NiFe2O4 > ZnFe2O4. The highly improved HER performance of CoFe2O4 is mainly due to a large number of exposed active sites, high electrical conductivity and low apparent activation energy, which are confirmed by a remarkable electrochemically active surface area (ECSA = 53.17 cm2), Nyquist plots analysis and Arrhenius plots measurement, respectively. Moreover, the CoFe2O4 electrode showed outstanding electrocatalytic stability even after 1000 cyclic voltametry tests. These results provide a promising avenue for developing cost-effective and high-efficiency electrocatalysts based on earth-abundant transition metal ferrite as advanced electrodes for large-scale energy conversion processes.

Carbon coated electric arc furnace dust prepared by one-pot pyrolysis: An efficient, low carbon footprint electrode material for lithium-ion batteries

This work offers useful insights into the evaluation of the electric arc furnace dust in green energy applications by surface engineering. To produce low-carbon-footprint electrodes, for the first time in the open literature, the practical pyrolysis (of sucrose) method is applied to create a nanometer-thick carbon layer over the dust. Advanced techniques are used to characterize the carbon-coated electric arc furnace flue dust morphologically, structurally, and chemically. Galvanostatic tests reveal that the carbon-coated dust exhibits 600 mAh g−1 discharge capacity after 250 cycles. The rate test proves that the carbon-coated dust can withstand a high current load (2A g−1) and delivers 540 mAh g−1 after 250 cycles when the current load is decreased to 0.1A g−1. This obtained capacity shows that with the correct material selection and process design, it is possible to produce low-carbon footprint electrodes at a low cost. Electrochemical characterizations indicate that the lithiation reaction of the carbon-coated dust takes place similarly to that of the anode materials which are made of synthetically fabricated carbon-coated transition metal oxides and/or ferrites. It is anticipated that this study sets an example for the valorization of the various industrial wastes in energy applications in the future.

Microwave Sol-gel Synthesis of Co, Ni, Cu, Mn Ferrites and the Investigation of Their Activity in the Oxidation Reaction of Carbon Monoxide

Background: The study effect of microwave radiation on the catalytic properties of transition metal ferrites synthesized by ceramic and sol-gel methods in the oxidation reaction of carbon monoxide into dioxide. Objective: This work aims to study the effect of microwave radiation on the production of cobalt, copper, nickel, and manganese ferrites by sol-gel combustion technology using various organic reagents and to study their catalytic activity in the oxidative conversion of carbon monoxide into dioxide. Methods: Microwave treatment was carried out on a setup based on an EM-G5593V microwave oven (Panasonic) with a magnetron power varying from 300 to 800 W with an operating frequency of 2450 MHz. X-ray phase analysis of the products was carried out on a Bruker D 2Phazer automatic diffractometer. The measurement of the specific surface area of the samples was determined by low-temperature nitrogen adsorption by the multipoint BET method on a SORBI-MS instrument (ZAO META, Russia). IR spectra were recorded using FT-IR LUMOS Bruker spectrometers. The micrographs of samples were analyzed on the Sigma VP (Carl Zeiss Jena) equipment. Results: It was determined that the most active catalysts for the oxidation of carbon monoxide to dioxide are ferrites obtained by the sol-gel combustion method using microwave radiation to "ignite" the gel. Conclusion: The use of microwave radiation in the preparation of ferrites by the sol-gel method with combustion can initiate a self-propagating exothermic combustion reaction in the entire volume of the sample in a very short time, measured in seconds. The catalytic activity in the oxidative conversion of carbon monoxide obtained by this method of ferrites is comparable to the activity of ferrites obtained by the sol-gel method with traditional combustion.

Adsorption efficiency of sol–gel derived nano metal ferrites, MFe2O4 (M = Ni, Zn, Cu) on the removal of Cr (VI) ions from aqueous solution

Adsorption efficiency of sol–gel derived nano metal ferrites, MFe2O4 (M = Ni, Zn, Cu) on the removal of Cr (VI) ions from aqueous solution

Room temperature magnetocaloric effect of Ce0.65Mg0.35Co3

The magnetocaloric (MC) effect of Ce0.65Mg0.35Co3 alloy is simulated using a phenomenological model (PM). MC parameters of Ce0.65Mg0.35Co3 alloy are obtained from modelling findings as the result of simulation for magnetization vs. temperature in a 0.1 T magnetic field. The full-width at half-maximum of 104 K is impressive, providing an important basis for operating the Ce0.65Mg0.35Co3 alloy in the magnetic refrigerator (MR). Since the Ce0.65Mg0.35Co3 alloy may be used as an effective MC material for MR throughout a wide temperature range, it can cover a significant and crucial range of temperatures, including room temperature and lower temperatures. The MC parameters of Ce0.65Mg0.35Co3 alloy are larger than those of metal oxide nanoparticles, ferrites, intermetallic compounds, and manganites that have been published previously, concluding that Ce0.65Mg0.35Co3 alloy can serve as an advantageous MC magnet for the MR.

Nano Size NiCuZnFe2O4 Tri Metal Spinel Ferrite: Synthesis, Characterizations and Additive for Thermolysis of Ammonium Perchlorate

AbstractFerrites especially transition metal based catalysts show a versatile catalytic ability for thermal decomposition of solid propellants. Herein, XRD, UV‐visible spectroscopy, Raman spectroscopy, and N2‐adsorption desorption analyses were used to analysis trimetallic nano‐ferrite NiCuZnFe2O4 synthesized by co‐precipitation method. The particle size of the NiCuZnFe2O4 found between 9–20 nm. Moreover, we have studied catalytic activity of tri metal ferrite (NiCuZnFe2O4) on thermal decomposition of propellant oxidizer ammonium perchlorate (AP) and monitored by simultaneous thermal analyses. The increased surface area, smaller band gap, and crystalline Raman phase of the AP + NiCuZnFe2O4 mixture contributed to substantial physico‐chemical and catalytic outcomes. The combination of AP with the nano‐catalyst NiCuZnFe2O4 reduced ignition delay, which was ascribed to a lower thermal decomposition temperature.

Wet-chemical synthesis of nanostructured Ce-doped mixed metal ferrites for the effective removal of azo dyes from industrial discharges

Today, photocatalysis is the most cost-effective and ecologically beneficial technique for tackling the growing problem of water pollution caused by rapid industrialization. The fabrication of a new photocatalyst with quicker charge transport, superior charge separation, narrow bandgap energy, reduced electron-hole pair recombination rate, and good light-harvesting characteristics is a major challenge for materials researchers. So herein, we used the microemulsion method to synthesize Ce-doped (rare-earth metal) cobalt/nickel mixed metal ferrite (C-X@CNMF, X = 0%, 3%, 6%, 9%, 12%, and 15%). Application studies revealed that C-9@CNMF material mineralizes the Congo red (CR) dye to a greater extent than that of C-0@CNMF under visible light irradiation. At the completion of the photodegradation reaction, nanostructured C-9@CNMF material completely mineralized CR-dye, whereas only 45.11%, 49.6%, and 73.3% of the CR-dye was removed by C-0@CNMF, C-3@CNMF, and C-15@CNMF nanoparticles. The kinetic tests showed that C-9@CNMF material mineralized the CR-dye at a rate (k = 0.0336 min−1) that is approximately 6.72 times quicker than that of the C-0@CNMF sample (0.0050 min−1). Aside from that, the C-9@CNMF material showed exceptional recyclability and photo-corrosion resistance, losing just 7.5% of its photocatalytic activity after five cycles of CR-dye degradation. The dominating photocatalytic performance of the C-9@CNMF sample is mainly attributed to its nanoarchitecture (44.8 nm), larger specific surface area (57.6 m2/g), tunable bandgap (2.13 eV), and effective charge separation characteristics.

Progress study on nickel ferrite alloy-graphene nanosheets nanocomposites as supercapacitor electrodes

Nickel ferrite (NiFe2O4) is a promising material for electrochemical supercapacitors among many metal ferrites. However, the low specific capacitance of NiFe2O4 limits its application. We present a new high-performance supercapacitor based on a nanocomposite material of NiFe alloy-graphene nanosheets (NiFe-A@GNS). We prepared NiFe2O4 nanoparticles using a simple liquid fusion method and used as a catalyst substrate for the chemical vapor deposition (CVD) synthesis of NiFe-A@GNS nanocomposite material. According to the XRD, TEM, SEM and Raman results, high-quality, crystalline, and graphitized GNS was successively composited with NiFe-A nanoparticles. Therefore, both pristine NiFe2O4 and the new composite material were evaluated as electrodes for supercapcitors. In the case of NiFe-A@GNS nanocomposite, we report a 3.2-fold increase in specific capacitance (845 F g − 1) when compared to the pristine NiFe2O4 (264 F g − 1). Furthermore, after 5000 cycles, the NiFe-A@GNS electrode retains 94.3% of its capacity, making it more stable than the NiFe2O4 electrode (62% after 2000 cycles). At 1.0 A g − 1 current density, the NiFe-A@GNS device has a high energy density (30.8 Wh kg−1) and a high power density (620 W kg−1). The synergistic effects of NiFe-A and graphene nanosheets, as well as the excellent surface characteristics, are the keys to the high performance of NiFe-A@GNS electrodes. Our design offers a promising method for developing high-performance supercapacitor devices.

Synthesis of Transition Metal Ferrites (Co, Cu, Ni, Mn) by the Sol-Gel Method with Combustion and the Use of Microwave Processing

This review considers recent work on the synthesis of transition metal ferrites (Co, Cu, Ni, Mn) by sol-gel method with combustion, as well as the effect of microwave radiation. Ferrites are interesting not only for magnetic and optical properties, but also for their catalytic ones. In recent years, there has been an increasing amount of literature, which investigates the catalytic properties of transition metal ferrites in various reac-tions, including oxidative reactions. Given the fact that various organic components are used as complexing agents and as a fuel in the sol-gel method with combustion, the review considers the influence of the organic reagent nature, its ratio to precursors, the pH of the medium, the power and time of microwave exposure to the process of ferrite formation as factors influencing the size of formed particles and their textural character-istics, which are of great importance in the catalysis. Recently, the attention of chemists working in the field of catalysis has been attracted by studies of the effect of physical fields, to which the microwave field be-longs, on various chemical processes, including the nanocatalysts synthesis. The use of microwave radiation in sol-gel synthesis of ferrite allows obtaining nanoferrites with high specific surface area. From this point of view, this paper considers the works of recent years devoted to the study of microwave sol-gel synthesis of ferrite.

Resistive switching of transition metal ferrites on silicon substrate

This letter reports on the development and characterization of ferrite based resistive switching devices that join the excellent multifunctional memory properties of ferrites and silicon processing technologies. The core of the resistive switching devices consists of a single transition metal ferrite (Co, Cu, Ni, and Zn) confirmed through energy dispersive x-ray spectroscopy and x-ray diffraction. The ferrites are spin coated onto processed silicon dies (acting as bottom electrode/substrate) and deposited with a silver top electrode. Both electrodes are active, providing additional charge carriers to the main redox reaction mechanism (found in ferrites), thus helping device stability. Characterization and analysis of the ferrite-silicon devices show low resistive state ohmic conduction as well as the non-linear conducting mechanisms (Schottky Emission and Poole Frenkel) found in previously reported ferrite resistive switching devices. An additional reaction mechanism (space charge limited current) was found that is attributed to the active electrodes through the influx of excess charge carriers.

Microwave-Assisted Auto-Combustion Synthesis of Binary/Ternary Co x Ni1-x Ferrite for Electrochemical Hydrogen and Oxygen Evolution.

Enormous efforts have been dedicated to engineering low-cost and efficient electrocatalysts for both hydrogen evolution and oxygen evolution reactions (HER and OER, respectively). For this, the current contribution reports the successful synthesis of binary/ternary metal ferrites (CoxNi1–xFerrite; x = 0.0, 0.1, 0.3, 0.5, 0.7, and 1.0) by a simple one-step microwave technique and subsequently discusses its chemical and electrochemical properties. The X-ray diffraction analysis substantiated the phase purity of the as-obtained catalysts with various compositions. Additionally, the morphology of the nanoparticles was identified via transmission electron microscopy. Further, the vibrating sample magnetometer justified the ferromagnetic character of the as-prepared products. The electrochemical measurements revealed that the as-prepared materials required the overpotentials of 422–600 and 419–467 mV for HER and OER, respectively, to afford current densities of 10 mA cm–2. In the general sense, Ni cation substitution with Co influenced favorably toward both HER and OER. Among all synthesized electrocatalysts, Co0.9Ni0.1Ferrite displayed the highest performance in terms of OER in 1 M KOH solution, which is related to the synergistic effect of multiple parameters including the optimal substitution amount of Co, the highest Brunauer–Emmett–Teller surface area, the smallest particle size among all samples (26.71 nm), and the lowest charge transfer resistance. The successful synthesis of ternary ferrites carried out for the first time via a microwave-assisted auto-combustion route opens up a new path for their applications in renewable energy technologies.

Mixed metal ferrite (Mn0.6Zn0.4Fe2O4) intercalated g-C3N4 nanocomposite: efficient sunlight driven photocatalyst for methylene blue degradation

Visible active mixed metal ferrite intercalated semiconductor photocatalyst Mn0.6Zn0.4Fe2O4/g-C3N4 was prepared via facile hydrothermal and liquid assembly method for methylene blue (MB) dye degradation. The prepared samples were well characterized in term of their functional groups, crystallinity, elemental analysis, surface morphology using Fourier transform infrared spectroscopy, x-ray diffraction spectroscopy, energy dispersive x-ray, and scanning electron microscopy, respectively. The optical response of catalysts was checked by estimating the energy band gap (E g) of semiconductor photocatalysts using UV–vis spectroscopy. The photoluminescence spectroscopy was also performed to estimate the reduction in emission intensity after insertion of g-C3N4 into Mn0.6Zn0.4Fe2O4. The novel composition of Mn0.6Zn0.4Fe2O4 with g-C3N4, improved the optical response of pristine photocatalysts due to the reduction in the energy band gap and insertion of heterojunction. The surface area analysis of Mn0.6Zn0.4Fe2O4 and Mn0.6Zn0.4Fe2O4/g-C3N4 were acquired by Brunauer–Emmett–Teller. Point zero charge was also determined to observe the surface behavior of composite under different solution pH. Various parameters such as pH, catalyst dose, oxidant dose, irradiation time and initial dye concentration were optimized, and their effects were studied in photo-Fenton process. It was observed that 98% MB dye was degraded under optimized conditions (pH = 8, composite dose = 50 mg/100 ml, oxidant dose = 7 mM, initial dye conc. = 10 ppm, and irradiation time = 120 min). The results showed that when the ferrites of mixed metals (Mn, Zn) were used with g-C3N4 their photocatalytic activity enhanced due to mutual effect of both mixed metals ferrite and g-C3N4, which is considerably higher than their individual effect already reported. Furthermore, the combined effect of independent variables was evaluated by response surface methodology.

Investigations on ternary transition metal ferrite: NiCoFe2O4 as potential electrode for supercapacitor prepared by microwave irradiation method

Ternary transition metal ferrite (NiCoFe2O4) has been successfully produced by a facile microwave-assisted method as an electrode material for supercapacitor applications. The structural single-phase nature is analysed by XRD pattern reveals the material belongs to cubic spinel structure with space group Fd3¯m. In addition, Rietveld refinement is used to confirm the structure from the powder X-ray diffraction data. The maximum entropy method also has been applied to find the electronic charge density that exists around the cation and anion sites in the compound. The UV spectral studies show the prepared nanomaterials have band gap of 1.43 eV and the magnetic studies confirm a ferromagnetic type with magnetization value of 0.615 emu g−1 and coercivity as 920.38 Oe. Using a three-electrode system, the electrochemical performance of the prepared nanomaterial is assessed by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic process in 3 M KOH electrolyte. The highest specific capacitance value of 314.97 F g−1 is observed at the scan rate of 5 mV s−1. The maximum energy density and power density values are 3.826 Wh Kg−1 and 1249.326 W Kg−1 respectively. It also has good retention of 93.65% for 5000 cycles at a current density 3 A g−1. Furthermore, an asymmetric supercapacitor device is fabricated which exhibits very high energy and power density of 6.4 Wh Kg−1 and 1904.7 W Kg−1 at a current density 10 A g−1.

Chemical Vapor Deposition of Cobalt and Nickel Ferrite Thin Films: Investigation of Structure and Pseudocapacitive Properties

AbstractTransition metal ferrites, such as CoFe2O4 (CFO) and NiFe2O4 (NFO), have gained increasing attention as potential materials for supercapacitors. Since chemical vapor deposition (CVD) offers advantages like interface quality to the underlying substrates and the possibility for coverage of 3D substrates, two CVD processes are reported for CFO and NFO. Growth rates amount to 150 to 200 nm h−1 and yield uniform, dense, and phase pure spinel ferrite films according to X‐ray diffraction (XRD), Raman spectroscopy, Rutherford backscattering spectrometry and nuclear reaction analysis (RBS/NRA) and scanning electron microscopy (SEM). Atom probe tomography (APT) and synchrotron X‐ray photoelectron spectroscopy (XPS) give insights into the vertical homogeneity and oxidation states in the CFO films. Cation disorder of CFO is analyzed for the first time from synchrotron‐based XPS. NFO is analyzed via lab‐based XPS. Depositions on conducting Ni and Ti substrates result in electrodes with pseudocapacitive behavior, as evidenced by cyclovoltammetry (CV) experiments. The interfacial capacitances of the electrodes are up to 185 µF cm−2.

Structural and Magnetoelectrical Properties of MFe2O4 (M = Co, Ni, Cu, Mg, and Zn) Ferrospinels Synthesized via an Egg-White Biotemplate.

Nanocrystalline metal ferrites (MFe2O4, M = Co, Ni, Cu, Mg, and Zn) were successfully synthesized via autocombustion synthesis using egg white. X-ray diffraction (XRD) measurements revealed the crystallization of the entire ferrites either in the tetragonal structure, such as in the case of CuFe2O4, or cubic spinels such as in other studied ferrites. The Fourier transform infrared spectral study revealed the characteristic vibration bands of ferrites. Compared to other synthesis methods, the observed variation in the obtained structural parameters could be due to the different cation distribution of the prepared ferrites. In agreement with XRD measurements, the transmission electron microscopy images showed agglomerated particles with cubic morphology for all ferrites. On the other hand, CuFe2O4 showed tetragonal morphology. The magnetization values were found to vary with the type of the metal ion, and CoFe2O4 showed the highest one (42.8 emu/g). Generally, the lower magnetization values obtained than those reported in the literature for all studied ferrites could be attributed to the smaller particle sizes or the cation redistribution. The obtained coercivity values are observed to be higher than their related values in the literature, exhibiting the impact of the present synthesis route. Ac-conductivity as a function of temperature and frequency indicated semiconducting properties with the observed change in the conduction mechanism by increasing the temperature. The obtained low dielectric constant values could suggest using the entire ferrites in high-frequency applications such as microwave devices.

Versatile Mesoporous Nanoparticles for Cell Applications.

Mesoporous silica nanostructures are emerging as a promising platform able to deal with challenges of many different applications in fields such as biomedicine and nanotechnology. The versatile physical and functional properties of these materials like high specific surface area, ordered porosity, chemical stability under temperature and pH variations, and biocompatible performance, offers new approaches to many biomedical applications ranging from drug delivery systems to biosensing, cell applications and tissue engineering. Their morphology, size and textural properties can be easily tailored by means of chemical control, giving rise to a variety of nanostructures with hexagonal (SBA15, MCM41) or cubic (SBA16) arrangement of channels and pore size ranging from 1.3 to 10 nm. Based on the versatility of their silane surface, a plethora of hybrid mesoporous matrices can be prepared incorporating new functionalities like contrast enhancement for magnetic resonance imaging, magnetic/plasmonic hyperthermia, drug delivery or cell applications by the simple grafting of superparamagnetic metal oxides (Fe₃O₄, transition metal ferrites) nanoparticles, noble metal (Au, Ag) nanoparticles, fluorescent moieties (fluorescein, rhodamine) or biological agents (mAb, mRNA, etc). The goal of this work is to present the development, by a facile soft template method, of size tailored mesoporous silica nanospheres from 20 to 350 nm (by means of chemical control), and highlight its versatility for surface grafting (with rhodamine and polydopamine) and their biological compatibility and efficient uptake by cultured HeLa cells. The combined, physicochemical and biological, properties indicate that MSNs are good candidates for cell tagging, gene transfer or targeted therapies.

A comparison study of MFe2O4 (M: Ni, Cu, Zn)-reduced graphene oxide nanocomposite for electrochemical detection of bisphenol A

In this work, the electrocatalytic activities and the sensing performances of a series of metal ferrites (MFe2O4, M: Ni, Cu, Zn) - reduced graphene oxide (rGO) nanocomposite (MFe2O4-rGO) prepared through a hydrothermal method were examined by using DPV, CV and EIS techniques. The electrochemical results exhibited that NiFe2O4-rGO nanocomposite modified screen-printed electrode (SPE) has a higher sensing performance towards the oxidation of bisphenol A (BPA) than those of the other ferrite (CuFe2O4, ZnFe2O4)-based SPEs. After optimizing crucial parameters such as accumulation time, accumulation potential and electrolyte pH, the DPV responses of NiFe2O4-rGO/SPE increased linearly with BPA concentration in the range of 0.05 μM to 25 μM (R2 = 0.9976) with a low detection limit of 10 nM and a high sensitivity of 0.6132 μA μM−1. The specificity of the fabricated sensor towards BPA was assessed by analyzing the interference effect of some inorganic salt ions and phenol derivatives. In addition, the sensor prepared to detect BPA in the water bottle sample using only a few drops of the real sample diluted with 0.1 M phosphate buffer solution gave satisfactory responses.

Assessment of crystallographic and magnetic phase stabilities of cubic copper ferrite at shocked conditions

In recent years, dynamic shock wave-driven investigation carried out on the crystallographic phase stabilities of nano-materials has led to the accumulation of massive explosion of innovations which materialize in identifying the efficient materials so that such kinds of assessments are highly required before putting them into practical applications. Surprisingly, at shocked conditions, most of the materials are found to have undergone phase transition or a variety of changes have been observed in their stability as well as efficiency. Hence, device engineers are highly focused on the search of high shock-resistant materials for applications point of view especially for aerospace, defense, and military applications. In the present context, we have chosen one of the most familiar divalent metal ferrites of cubic copper ferrite nanocrystalline material (CuFe2O4 NPs) for the analysis of structural stability and the results have been screened by X-ray diffraction (XRD) as well as ultra-violet diffuse reflectance spectroscopic (UV-DRS) techniques. Magnetic phase stability has been evaluated by vibrating sample magnetometer (VSM). Interestingly, the title ferrite does not experience any crystallographic and magnetic phase transition even though it has polymorphic nature and variety of magnetic states. Therefore, it could be confirmed that CuFe2O4 NPs have considerable shock-resistant behavior for both crystallographic and magnetic phases. The results are discussed in the upcoming sections.