Fe-doped NiO Nanoparticles Research Articles

Improved electrochemical performance of the iron-doped NiO nanoparticles at varying calcination temperatures and examination of their supercapacitor applications

The scientific community is interested in increasing oxide electrochemical characteristics for supercapacitor applications. The present research explores the development of supercapacitor electrodes using Fe-doped NiO nanoparticles synthesised via chemical co-precipitation method with varied calcination temperatures (350, 550, and 750 °C). The key innovation of the work lies in the systematic investigation of the effects of calcination temperature on the electrochemical properties and structural characteristics of the Fe-doped NiO nanoparticles. X-ray diffraction (XRD) analysis revealed a trend of increasing crystallite size with rising temperatures, and optical studies indicated a decreasing trend in the energy band gap from 3.67 eV to 3.23 eV. Fourier transform infrared (FTIR) spectroscopy confirmed the metal-oxygen bond in the molecules. Scanning electron microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM) analysis showed the mesoporous spherical morphology of the nanoparticles. Energy-dispersive X-ray spectroscopy (EDX) ensured the samples' elemental composition purity. Brunauer–Emmett–Teller (BET) shows a specific surface area of around 180.8 m2/g was obtained for Fe-doped NiO nanoparticles at 350 °C. Electrochemical tests demonstrated that the Fe-doped NiO electrodes, especially calcined at 350 °C, exhibit superior specific capacitance values (635 F/g) and impressive cycle stability with 93.29 % capacitance retention after 5000 cycles. The present demonstrates the potential of optimizing calcination temperatures to enhance the electrochemical performance and stability of Fe-doped NiO supercapacitor electrodes, marking a significant advancement in supercapacitor technology.

Fe-doped NiO nanoparticles: Microscopic and spectroscopic characterizations

Ni1−xFexO single phase nanoparticles, synthesized by lyophilization and heat treatment, were characterized by microscopic and spectroscopic techniques searching for evidence of a core-shell structure. Transmission electron microscopy, X-ray photoelectron spectroscopy, and more extensively Mössbauer spectroscopy were applied in this study. Consistent with structural and magnetic analyses previously reported, these findings support the plausibility of a core-shell structure in Ni1−xFexO nanoparticles. The shell was found to be very thin and more iron-rich than the core. The core has a lower iron concentration than the nominal overall concentration. The nanoparticles were not completely magnetized at room temperature, but below 200 °C the iron moments froze almost completely.

Magnetic properties of Fe-doped NiO nanoparticles

Undoped and Fe-doped NiO nanoparticles were successfully synthesized using a lyophilization method and systematically characterized through magnetization techniques over a wide temperature range, with varying intensity and frequency of the applied magnetic fields. The Ni1-xFexO nanoparticles can be described by a core-shell model, which reveals that Fe doping enhances exchange interactions in correlation with nanoparticle size reduction. The nanoparticles exhibit a superparamagnetic blocking transition, primarily attributed to their cores, at temperatures ranging from above room temperature to low temperatures, depending on the Fe-doping level and sample synthesis temperature. The nanoparticle shells also exhibit a transition at low temperatures, in this case to a cluster-glass-like state, caused by the dipolar magnetic interactions between the net magnetic moments of the clusters. Their freezing temperature shifts to higher temperatures as the Fe-doping level increases. The existence of an exchange bias interaction was observed, thus validating the core-shell model proposed.

Synthesis and Characterizations of Fe-Doped NiO Nanoparticles and Their Potential Photocatalytic Dye Degradation Activities

Recently, the preparation of smart multifunctional hybrid nanoparticles has captured significant interest in versatile areas, including medicine, environment, and food, due to their enhanced physicochemical properties. The present study focuses on the synthesis of Fe-doped NiO nanoparticles by the coprecipitation method using the sources of nickel (II) acetate tetrahydrate and iron (III) nitrate nonahydrate. The prepared Fe-doped NiO nanoparticles are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, UV–visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and X-ray photon spectroscopic analysis. The XRD results clearly confirm the face-centered cubic structure and polycrystalline nature of the synthesized Fe-NiO nanoparticles. The Tauc plot analysis revealed that the bandgap energy of the Fe-doped NiO nanoparticles decreased with the increasing concentration of the Fe dopant from 2% to 8%. The XPS analysis of the samples exhibited the existence of elements, including Fe, Ni, and O, with the absence of any surplus compounds. The FE-SEM and TEM analyses proved the formation of nanostructured Fe-NiO with few spherical and mostly unevenly shaped particles. Further, the photocatalytic efficiency of the prepared Fe-doped NiO nanoparticles were identified by using the cationic dye rhodamine B (Rh-B). The photocatalytic results proved the 8% of Fe doped with NiO nanoparticles achieved 99% of Rh-B degradation within 40 min of visible-light irradiation. Hence, the results of the present study exemplified the Fe-doped NiO nanoparticles have acted as a noticeable photocatalyst to degrade the Rh-B dye.

Iron-doped nickel oxide as a potential biosensor of urea determination via voltammetry

Biosensor made from metal oxide is reported to be useful for sensing urea levels in the human body, NiO nanoparticles have successfully been utilized to make urea biosensors. Ni-based electrodes are favorable for making a low-cost urea biosensor. Fe-doped NiO nanoparticles were prepared by the sol-gel method. Different concentrations of Iron doping were done in NiO and its sensing response was measured. XRD characterization was performed to determine the material's structure, phase purity, and crystallinity. Also, this characterization showed that the NiO compound is pure and single phase with a cubic structure. CV, time response FTIR, and UV–Visible spectroscopy were performed on the pure and Fe-doped NiO samples. The CV curve of a Fe-doped NiO-modified electrode in the presence of urea showed an excellent electrochemical response. Furthermore, it was also observed that with the increase in Fe doping, the sensing response and absorption properties of the samples were enhanced.

Probing into the physicochemical consequences of pristine and X0.06Ni0.94O (X = Co, Fe, Cu) nanoparticles for bactericidal, antifungal and hemolytic competency

Nano-scaled transition metal oxides are massively gaining an exciting horizon of research interest among material scientists by triggering scientific attention due to its prime advancements in physico-chemical, magneto-optical, electro-chemical, bio-medical and bio-compatible characteristics. The current work highlights the fabrication and formalisation of pure and X0.06Ni0.94O (X = Co, Fe, Cu) nanoparticles via bottom-up sol-gel pathway employing citric acid as the gelling factor. The crystallite size evaluated from X-Ray Diffraction (XRD) analysis decreased with respect to doping were estimated by successive systems among which Halder-Wagner (H-W) and Wagner-Agua (W-A) approach delivered prime results. Fourier Transform Infra-Red (FTIR) spectroscopy analysis regulated at room temperature in the mid infrared frequency continuum 400–4000 cm−1 confirmed the cubic conformation and the presence of predicted functional groups in the as-synthesized nanoparticles. The bandgap energy calculated from Ultra Violet-visible (UV–vis) spectroscopy is found to decrease for Co-NiO and Cu-NiO nanoparticles and increased for Fe doped NiO nanoparticles in comparison with the bandgap of pure NPs reasoned out by the Burstein-Moss shift. The device dependent parameter Urbach energy, and other pivotal optical parameters crucial in the fabrication of optoelectronic devices were evaluated. Surface morphological features and porous network of doped nanoparticles were investigated from Scanning Electron Microscopy (SEM) technique. Energy Dispersive X-ray (EDX) spectra ascertained the molecular matrix array and elemental composition in synthesized samples. The surface area measured from Brunauer-Emmett-Teller (BET) analysis revealed higher surface area (42 m2/g) for Fe-doped NiO nanoparticles than other counterparts. The thermal decomposition and stability of the pure and doped samples were analysed by Thermo-Gravimetric (TG) studies. The fundamental kinetic and thermodynamic parameters such as entropy, enthalpy, activation and Gibb’s free energy were elucidated through six different models viz., Coats-Redfern (CR), Piloyan-Novikava (PN), Horowitz-Metzger (HM), Van-Krevelen (VK), MacCallum-Tanner (MT) and Broido methods. Vibrating Sample Magnetometer (VSM) analysis coupled with the Law of Approach to Saturation (LAS) operandi extracted two critical magnetic criteria and the saturation magnetization is noticed to reduce with doping. The antibacterial and antifungal efficacies of the as-synthesized NPs were deeply discussed by portraying the nanoparticles-microbes interface. Iron and copper doped nickel oxide nanoparticles encountered favorable antimicrobial activity against pathogenic organisms. Furthermore, the bio-compatibility nature of the NPs was examined through hemolytic activity and the samples exhibited non-toxic behavior towards human cells till 50 μg/ml.

Significant improvement in the structural, microstructural, and room-temperature magnetic properties of Fe-doped NiO nanoparticles prepared by the solution combustion method

Significant improvement in the structural, microstructural, and room-temperature magnetic properties of Fe-doped NiO nanoparticles prepared by the solution combustion method

Room Temperature Magnetic Memory Effect in Cluster-Glassy Fe-doped NiO Nanoparticles.

The Fe-doped NiO nanoparticles that were synthesized using a co-precipitation method are characterized by enhanced room-temperature ferromagnetic property evident from magnetic measurements. Neutron powder diffraction experiments suggested an increment of the magnetic moment of 3d ions in the nanoparticles as a function of Fe-concentration. The temperature, time, and field-dependent magnetization measurements show that the effect of Fe-doping in NiO has enhanced the intraparticle interactions due to formed defect clusters. The intraparticle interactions are proposed to bring additional magnetic anisotropy energy barriers that affect the overall magnetic moment relaxation process and emerging as room temperature magnetic memory. The outcome of this study is attractive for the future development of the room temperature ferromagnetic oxide system to facilitate the integration of spintronic devices and understanding of their fundamental physics.

Thermal annealing induced enhancement of room temperature magnetic memory effect in Fe-doped NiO nanoparticles

We report room temperature (RT) ferromagnetism and magnetic memory effect in Ni0.95Fe0.05O nanoparticles (NPs) synthesize by hydrothermal method followed by post-annealing in an ambient atmosphere. The temperature and time-dependent magnetization measurements show that the effect of post-annealing at higher temperatures leads to enhancement in the intraparticle interactions. The enhanced intraparticle interaction has provided additional magnetic anisotropy energy resulting in RT ferromagnetic (FM) properties and enhanced magnetic memory effect. The findings from this study will be useful for the development and understanding of RT FM materials to facilitate the integration of spintronic devices.

Enhanced photocatalytic Activity of Ferromagnetic Fe-doped NiO nanoparticles

The Ni1-xFexO (x = 0.00, 0.02, 0.04, 0.06 and 0.08) nanoparticles (NPs) has been synthesized via composite hydroxide mediated (CHM) synthesis approach. The single phase formation of NiO NPs was achieved without any impurity phase confirmed by XRD and average crystallite size showed minor decreasing trend with increasing Fe doping concentration. FTIR spectra showed dip in 417-432 cm−1 range which confirmed the existence of Ni-O bonding. In Raman spectra, the weak two-magnon (2 M) band at 1472 cm−1 in pure NiO NPs indicate suppressed antiferromagnetism (AFM) due to smaller average crystallite size and superparamagnetic contribution from the uncompensated surface/core spins. The absence of 2 M band in Fe doped samples is due to onset of ferromagnetism in these NPs. The M-H loops showed the room temperature ferromagnetism in Fe doped samples due to double exchange interaction of mixed valance states of Fe. The energy band gap showed minor increasing trend with increasing Fe doping concentration and is mainly attributed to Moss-Burstein effect. The photocatalytic activity showed an increasing trend with increasing Fe doping due to generation oxygen vacancies which served as energy traps and restricted the electron-hole recombination. Therefore, the bifunctional ferromagnetic Fe doped NiO NPs are more favourable for photocatalysis along with their ability of collection for re-use in the degradation process.

Understanding the Magnetic Memory Effect in Fe-Doped NiO Nanoparticles for the Development of Spintronic Devices

Uniform hexagonal single phase Ni1–xFexO (x = 0, 0.01, 0.05, and 0.1) nanoparticles synthesized by a standard hydrothermal method are characterized with an enhanced lattice expansion along with a d...

The Calotropis procera Transformed Green NiO and Fe‐NiO Nanoparticles for Diaryl Pyrimidinones Synthesis in Hydrotropic Medium at Room Temperature

AbstractWe report the synthesis of NiO and Fe doped NiO nanoparticles by simple and cost effective Calotropis procera leaf extract assisted green co‐precipitation method. The leaf extract of Calotropis procera acts as reducing as well as capping agent for the synthesis of NiO and Fe doped NiO. The presence of –OH and aldehydic group (‐CHO) on synthesized nanoparticle imparts their strong interaction with synthesized nanoparticles, conveying efficient catalyst for heterocycle synthesis. The proficient catalytic application of biogenic NiO and Fe doped NiO NPs were explored in aqueous hydrotropic solution for syntheses of diaryl pyrimidinones at room temperature. The synthesized catalysts are efficient in terms of yield, reaction time and reusability. The NiO or Fe doped NiO/NaPTS/27°C is efficient, highly sustainable catalytic system for heterocycle synthesis at room temperature. Accordingly, Fe doped NiO/NaPTS proved to be a better catalytic system than NiO/NaPTS in water.

Effect of Fe Substitution on Microstructure and Magnetic Properties of Ni1−xFexO2 Nanoparticles

Fe-substituted NiO nanoparticles (Ni1−xFexO2) (x= 0.00, 0.03, 0.05, 0.07, and 0.09) were synthesised using ball-milling method followed by vacuum sintering and studied for their microstructural and magnetic properties. All the samples show a cubic structure with a crystallite size of 17–26 nm. Secondary phases related to Fe2O3 were identified from XRD, indicating that the observed ferromagnetism may be due to the dopants. The doping of Fe ions does not cause any significant variation in the crystal structure. The pure NiO nanoparticles were weak ferromagnetic in nature, and Fe-doped NiO nanoparticles exhibit room temperature ferromagnetism. The strength of magnetization increased from 0.57 to 0.94 emu/g with an increase of Fe concentration from 3 to 7 at.%, respectively. A high coercive field of 173 Oe was observed for the Ni1−xFexO2 nanoparticles at x= 0.09. The results and the process of development of ferromagnetism at room temperature in the Ni1−xFexO2 nanoparticles were presented and discussed in detail.

Structure, Magnetic Property and Energy Band Gap of Fe-Doped NiO Nanoparticles Prepared by Co-Precipitation Method

Fe-doped NiO nanoparticles was prepared by the co-precipitation method. The precipitation solution were used the concentration of FeSO4 mixing NiCl2 for 0.5 M. The precipitation process was used a magnetic stirrer of 1100 rpm, a temperature of 30-60 OC for 0.5 h and the dropping a NaOH of 0.5 M in the mixing solution. The precipitate product was dried at the temperature of 120 OC for 9 h and calcined in a furnace at the temperature of 400 OC for 4 h in air atmosphere. The powder product was analyzed a crystal structure by a x-rays diffractometer, calculated an energy band gap by UV-VIS spectrophotometer, measured a magnetic properties by a vibrating sample magnetometer and explained morphology by a scanning electron microscope. It was found that the crystal structure was shown face center cubic. The nanoparticles in the range of 30-100 nm was observed the morphology of the optimum product. However, the coercive, the magnetic moment and the energy band gap was found the optimum at the doping Fe of 8 wt% at the precipitation temperature of 40 OC.

Structural and Magnetic Properties of NiO and Fe-doped NiO Nanoparticles Synthesized by Chemical Co-precipitation Method

The NiO and Fe-doped NiO nanoparticles are prepared by a chemical co-precipitation method and calcinated at 400°C and 700°C. The structural, morphological, compositional and magnetic properties of synthesized nanoparticles are studied by powder XRD, FESEM, EDX, FTIR spectroscopy and VSM. The powder XRD result revealed that the obtained samples are nickel oxide with face centered cubic structure. The EDX and FTIR analyses confirm the formation of NiO nanoparticles and the presence of Ferrous in the Fe doped NiO. The crystallite size, determined from XRD, increases with calcination temperature and decreases with the insertion of Fe ions. FESEM analysis also indicates a decrease in the particle size with Fe insertion. The VSM studies show that NiO without Fe doping is superparamagnetic while the Fe doped NiO is ferromagnetic at room temperature.

Tuning the surface anisotropy in Fe-doped NiO nanoparticles

Ni(1-x)FexO nanoparticles have been obtained by the co-precipitation chemical route. X-ray diffraction analyses using Rietveld refinement have shown a slight decrease in the microstrain and mean particle size as a function of the Fe content. The zero-field-cooling (ZFC) and field-cooling (FC) magnetization curves show superparamagnetic behavior at high temperatures and a low temperature peak (at T = 11 K), which is enhanced with increasing Fe concentration. Unusual behavior of the coercive field in the low temperature region and an exchange bias behavior were also observed. A decrease in the Fe concentration induces an increase in the exchange bias field. We argue that these behaviors can be linked with the strengthening of surface anisotropy caused by the incorporation of Fe ions.

Synthesis and microwave absorption enhancement of Fe-doped NiO@SiO2@graphene nanocomposites

Abstract Fe-doped NiO@SiO 2 @graphene nanocomposites have been successfully fabricated for the first time, in which Fe-doped NiO nanoparticles are about 3 nm in diameter. In order to measure their electromagnetic properties, Fe-doped NiO@SiO 2 @graphene (25 wt%) wax composites were then prepared. The experimental results show that Fe-doped NiO@SiO 2 @graphene nanocomposites exhibit significantly enhanced microwave absorption performance in terms of both the maximum reflection loss value and the absorption bandwidth in comparison with NiO@SiO 2 @graphene. The maximum reflection loss of Fe-doped NiO@SiO 2 @graphene nanocomposites can reach −51.2 dB at 8.6 GHz with a thickness of 4 mm, and the absorption bandwidth with the reflection loss below −10 dB is 4 GHz (from 7 to 11 GHz). Therefore, this kind of nanocomposites may have the potential as high-efficient absorbers for microwave absorption applications.

Magnetic properties of Fe-doped NiO nanoparticles

Ni1−xFexO (x = 0, 0.05, 0.1) nanoparticles with several nanometers encapsulated with amorphous SiO2 were prepared by our novel preparation method. A NiO single phase structure was confirmed using the X-ray diffraction measurements. It is considered that Ni ions are replaced by Fe ions because it is observed that the lattice constant decreases. The temperature dependence behavior of the magnetization revealed that the blocking temperature, TB, shifted from 17 to 57 K as the amount of Fe ions increased, and that below TB, ferromagnetic behaviors were exhibited. The coercive force, HC, increased from 0.8 to 1.5 kOe as the amount of Fe ions increased.

Structural and magnetic properties of pristine and Fe-doped NiO nanoparticles synthesized by the co-precipitation method

Ni1−xFexO (x=0 and 0.03) nanoparticles are synthesized by a chemical route. XRD and TEM measurements confirm phase purity and crystallinity of the nanoparticles. Fe substitution in NiO reduces considerably the average particle size of the nanoparticles. The pristine NiO sample with size 14nm and Fe-substituted sample having size 7nm show room temperature ferromagnetism. The pristine NiO having 31nm size and Fe-substituted sample with size 25nm are found to be antiferromagnetic. The M–H and M–T behavior of the pristine and Fe-doped samples are explained with a core–shell model with an antiferromagnetic core and a ferromagnetic shell. The disordered spins at the shell give rise to a spin-glass like frozen state below 10K. The obtained room temperature ferromagnetism in the pristine and Fe-doped NiO has been attributed to particle size effect.