Nickel Manganite Research Articles

Review on the synthesis routes of nickel manganite – a potential material for thermistor applications

Review on the synthesis routes of nickel manganite – a potential material for thermistor applications

Flexible supercapacitors based on in-situ synthesis of composite nickel manganite@reduced graphene oxide nanosheets cathode: An integration of high mechanical flexibility and energy storage

Supercapacitors have attracted considerable attention in the context of electric vehicles, renewable energy storage, and industrial equipment. Nevertheless, further work is required to enhance the energy storage performance and improve the adaptability of supercapacitors under mechanical loads. To address these challenges, we propose a novel design strategy for composite micro-nano structures of reduced graphene oxide coated in situ growth of nickel manganite nanoarrays on the carbon fiber surface (CF@NiMn2O4@rGO). This design enables the fabrication of flexible supercapacitor electrodes with optimised electrochemical and mechanical properties. The CF@NiMn2O4@rGO cathode exhibits a synergistic effect that enhances energy storage, as evidenced by a high specific capacitance of 1003.35 F g−1 (at 10 mA cm−2) and exceptional cycling stability over more than 4000 cycles. Furthermore, the flexible carbon fiber (CF) and in-situ grown nickel manganite@reduced graphene oxide (NiMn2O4@rGO) contribute to improved mechanical properties of the electrode. The assembled supercapacitor exhibits both high energy density and cycling stability. Notably, the flexible bending angle ranging from 0° to 180° has minimal impact on the energy storage performance of this flexible supercapacitor. Even under a bending angle of 180°, it successfully powers a small light bulb. This novel nanostructured material presents an innovative approach for designing flexible supercapacitors.

Kinetics and thermodynamics studies of nickel manganite nanoparticle as photocatalyst and fuel additive

In this study, nickel manganite (NiMn2O4) nanoparticles were prepared using a hydrothermal method and examined its potential as a photocatalyst for the Acid Green 25 (AG-25) dye degradation. The nanoparticles were subjected to structural analysis using X-ray diffraction (XRD) and morphological analysis using scanning electron microscopy (SEM). The study examined the kinetics and thermodynamics of degradation processes that are catalyzed by photocatalysis. To ascertain their effect on dye degradation, several parameters, such as catalyst dose, H2O2 concentration, and temperature, were investigated. With a temperature of 315 K in a pseudo-first-order kinetic reaction, a 0.3 M H2O2 concentration, 0.05 mg/mL catalyst dose, and a promising removal efficiency of 96 % was achieved by the NiMn2O4 NPs in 40 min. Thermodynamic analysis revealed the spontaneous and entropy-driven nature of catalytic degradation, progressing favorably at elevated temperatures. Additionally, the NiMn2O4 NPs were applied as a fuel additive to analyze its influence on combustion and the physical characteristics of the modified fuel. The modified fuel demonstrated exceptional catalytic efficiency, emphasizing the potential of the NiMn2O4 NPs as an effective additive.

Improved Cycle Performance of Li-CO2 Batteries with Nickel Manganite Supported Carbon Nanotube NiMn2O4 @CNT Cathode

Rechargeable Li-CO2 batteries have emerged as promising candidates for next generation batteries due to their low cost, high theoretical capacity, and ability to capture the greenhouse gas CO2. However, these batteries still face challenges such as slow reaction kinetic and short cycle performance due to the accumulation of discharge products. To address this issue, it is necessary to design and develop high efficiency electrocatalysts that can improve CO2 reduction reaction. In this study, we report the use of NiMn2O4 electrocatalysts combined with multiwall carbon nanotubes as a cathode material in the Li-CO2 batteries. This combination proved effective in decomposing discharge products and enhancing cycle performance. The battery shows stable discharge–charge cycles for at least 30 cycles with a high limited capacity of 1000 mAh g−1 at current density of 100 mA g−1. Furthermore, the battery with the NiMn2O4@CNT catalyst exhibits a reversible discharge capacity of 2636 mAh g−1. To gain a better understanding of the reaction mechanism of Li-CO2 batteries, spectroscopies and microscopies were employed to identify the chemical composition of the discharge products. This work paves a pathway to increase cycle performance in metal-CO2 batteries, which could have significant implications for energy storage and the reduction of greenhouse gas emissions.

La1.5Sr1.5Mn1.5Ni0.5O7 ±δ Vs La1.5Sr1.5Co1.5Ni0.5O7 ±δ: Exsolved Materials as Anodic Layers for Direct Biogas-Fueled SOFC

Currently, one of the main problems in commercial SOFC systems fueled directly with hydrocarbon compounds, such as biogas, is the high risk of blocking the active phase on the anode side (e.g. Ni-YSZ) due to carbon formation/deposition during the conversion of fuel into power energy. This issue causes a lowering in the overall performance and durability of the cell. Therefore, to overcome this deactivation mechanism, it was successfully demonstrated that an additional anodic active layer in commercial SOFC using materials based on exsoluted perovskites could be an interesting and viable alternative. This asseveration is based on the fact that using this kind of material is possible to get heterogeneous surface systems with highly stable and electrocatalytically active embedded nanoparticles uniformly distributed on the surface with a high carbon coking tolerance in a hydrocarbon fuel atmosphere.This study aimed to evaluate and compare the electrocatalytic behaviour of two new catalytic materials with Ni exsolution for direct dry biogas-fueled SOFC. The starting materials were Ruddlesden-Popper-type based on a nickel manganite (La1.5Sr1.5Mn1.5Ni0.5O7±δ or LSMN) and nickel cobaltite (La1.5Sr1.5Co1.5Ni0.5O7±δ or LSCN). Both materials have been synthesized by the Pechini method using stoichiometric amounts of precursors as nitrates. Once the respective gels have been formed, they were treated in the air at two dwell temperatures, 300°C for 2 h and 500°C for 3 h, to ensure the total elimination of the organic compounds. Finally, the resulting powders were treated in air at 1300°C for 12h and then, physicochemically characterized. For the electrochemical characterization, the as-treated powders were mixed individually with Gd0.1Ce0.9O2 (CGO) in a weight ratio of 70:30 using a ball milling for 6h. Finally, to get the slurry for the coating layer, each mixture (LSMN+CGO and LSCN+CGO) was ground for an additional 2h in the presence of 8 wt % of triethanolamine, 2 wt % polyvinyl butyral resin (BUTVAR B-98) and 2-propanol. Commercial button SOFC cells by InDEC® (anode-supported cell Ni-YSZ/YSZ/LSM) were painted on the anode side getting an active area of 2 cm2. The experiments were carried out at 800°C with pre-conditioning using diluted H2 and then, with simulated dry biogas. A Biologic tool was used as a device for the electrochemical measurements.The purpose of this communication is to present the results of experiments with two button cells derived from the same large area commercial cell (anode supporting cell) coated with the two electrocatalysts developed in this work. The electrochemical test carried out for more than 200 h demonstrated that this external functional layer on the anode side contributes to getting a stable potential within the whole working time at the selected galvanostatic conditions (500 mA cm−2). By comparing the results of these two tests, the exsolved LSCN layer showed better perfomances, because of the the B-site doped with Co instead of Mn which is responsible for an enhanced O2- transport within the crystal structures. Finally, post-reaction characterization revealed minimum/null carbonous species in both cases which suggests that the classical risks caused by the direct use of hydrocarbon fuels in commercial SOFC can be suppressed with this kind of approach which would lead us to think about the use of this type of materials in a next level or further electrochemical applications. Acknowledgements The authors acknowledge the project entitled "Direct utilisation of bio-fuels in solid oxide fuel cells for sustainable and decentralised electric power production and heat (DIRECTBIOPOWER)" Grant Agreement number: 2017FCFYHK.The authors acknowledge the Ministry of Ecological Transition of Italy (MiTE) for funding this research through the AdP "Piano Operativo di Ricerca (POR) sull'idrogeno verde Figure 1

Highly active and stable Ru–(OH)-based catalysts supported on Ni–manganite for the base-free aerobic oxidation of 5-hydroxymethyl furfural to 2,5-furan dicarboxylic acid in a noble water–organic solvent system

Highly efficient and robust Ru supported on nickel–manganite catalysts for selective conversion of 5-hydroxymethyl furfural into 2,5-furan dicarboxylic acid in a solvent mixture of noble water and acetone with eliminating homogeneous base addition.

Study of catalytic oxidation of toluene using Cu-Mn, Co-Mn and Ni-Mn mixed oxides catalysts

The successful synthesis of AMn2O4 (A = Co, Cu, and Ni) spinels via solution combustion was achieved in less time than other methods. All catalysts with the same fuel/nitrate ratio were used to oxidize toluene, and the relationship between their properties and activities was investigated. Among all, nickel manganite exhibited the most promising activity, and by changing the fuel/nitrate ratio, it was sought to obtain the most appropriate structure for the reaction studied. Physico-chemical analysis was used to define the characteristics of the synthesized catalysts. The results showed the successful synthesis of spinels and indicated that other materials peaks (single oxide phases) exist in the catalyst structure. BET-BJH analyses reveal the mesoporous structures and, given the limitations of the equipment, were all classified as less than 10 m2/g. The SEM images evidence the influence of the urea content used. The particle size increases at higher fuel/nitrate ratios. Samples of NiMn1.67 and NiMn2.08 showed larger and denser, sparsely dispersed clusters. Simultaneously considering reactor analysis and test results, it was found that the synthesized catalyst with a fuel/nitrate ratio of 0.5 has the best performance on toluene oxidation.

Triple Probe Heat Pulse (TPHP) Soil Moisture Content and Temperature Monitoring Digital System Using Nanomaterials based Sensor Elements for Precision Agriculture

I discuss the TPHP soil moisture content and temperature measuring digital system using Indium doped Tin Oxide nanopowder (ITO) electric heater and Nickel manganite (NiMn2O4) nanoceramic powder thermistor as a temperature sensor fabrication, characterization, calibration, and testing. The NiMn2O4 nanoceramic powder is synthesized using the wet chemical method and the ITO nanopowder-based heater is fabricated by a simple fill and press method. The heater, temperature sensor, Atmega328 microcontroller with its software, stainless steel cylindrical tubes, and 3D-printed package are used to fabricate the device. The distance between the heater and the temperature sensor is set to 0.006 m and heat pulse duration is set to 240 s. The heater consumes 3.587W electric power. The temperature sensor can measure the soil temperature up to 50°C. The system is capable of measuring volumetric soil moisture content from 3% to 37% efficiently with a strong correlation coefficient of 0.997 with respect to the standard. The test result shows that there is less than a 2.8% error which is the smallest among the category and the sensitivity of the sensor at volumetric soil moisture content ( θ v ) = 0.28 m 3 m − 3 becomes 3.14 ∘ C per m 3 m − 3 . The developed system is simple to fabricate and operate highly precise, low cost, low power and light in weight.

Insights on a Ruddlesden-Popper phase as an active layer for a solid oxide fuel cell fed with dry biogas

Solid oxide fuel cell (SOFC) is a mature opportunity for producing power energy in remote areas like islands, where access to the electrical grid is not favoured, and gas distribution is the only viable approach. In this context, generally, biogas represents the most convenient fuel resources in these areas. However, the direct use of biogas in SOFCs is still an issue to be solved due to its negative effect on the conventional Ni-YSZ anode. In this study, to overcome this issue, we suggested using a protective layer coated on the anode of a commercial SOFC. A nickel manganite showing mixed ionic and electronic conductivity tailored specifically for this approach was investigated. The preliminary characterisations showed that the formation of a Ruddlesden-Popper (RP) n = 1 structure supporting fine encapsulated particles based on Ni was formed around 800 °C in consequence of the reducing environment. The electrochemical experiments carried out for 270 h demonstrated for the coated cell significant stability in the presence of dry biogas, albeit an ageing effect was noticed in the electrical percolation of both cell electrodes. The post mortem analyses revealed an attractive redox property for the nickel manganite, which partially returned to the RP n = 2 phase. Moreover, the absence of carbon deposits on the anode suggests possible applications for this approach.

Sol-Gel Co-Precipitation Synthesis, Anticoagulant and Anti-Platelet Activities of Copper-Doped Nickel Manganite Nanoparticles.

Copper-substituted nickel manganites Ni(1−x)CuxMn2O4 (Ni-TCE-NPs) were produced by co-precipitation route (sol–gel) at room temperature. Ni(1−x)CuxMn2O4-Bio (NCB) NPs were studied by powder X-ray diffraction technique, scanning electron microscopy and Raman spectroscopy. XRD spectra authenticated the copper-doped nickel manganites’ formation with particle size 23–28 nm. A significant decrease in the lattice parameter confirmed the doping of copper ions into the nickel manganites. Microscopy (SEM) was used to estimate the grain size, shape and uniformity, revealing the non-uniform agglomerated polygon and plate-like microstructure. The NCB-NPs showed anticoagulant activity by enhancing the coagulation time of citrated plasma of human beings. NCB-NPs with x = 0.35 and 0.45 have increased clotting time from control 133 ± 4 s to 401 ± 7 s and 3554 ± 80 s, respectively, and others around 134 s. Additionally NCB-NPs with x = 0.35, 0.45 inhibited the platelet aggregation by 80% and 92%, while remaining inhibited with only 30%. NCB-NPs did not show hemolytic activity in RBC cells intimate its non-toxic nature. Finally, NCB-NPs were non-toxic and known to exhibit anti-blood-clotting and antiplatelet activities, which can be used in the field of biomedical applications, especially as antithrombotic agents.

Tailoring the properties of Ni-Mn based NTC thermistors by Cu and Li addition

The influence of Cu and Li doping in the structural and R-T characteristics of Ni-Mn-based spinel oxide negative temperature coefficient (NTC) thermistors prepared using the conventional solid-state synthesis method was investigated in this study. The doping of Cu and Li in nickel manganite plays an important role in tailoring the thermistor parameters. The structural characterization of the prepared samples using XRD revealed that the basic structure of the samples is not altered by the addition of the dopants Cu and Li. The particle size of the samples was obtained at less than 50 nm. R-T characteristics showed a decrease in resistance with temperature. It was observed that the addition of dopant Cu in a minimal amount helps to tune the resistance of the thermistor in the required range and Li addition, as a dopant, stabilized the thermistor parameters B and alpha.

Nickel Manganite-Sodium Alginate Nano-Biocomposite for Temperature Sensing

Nanocrystalline nickel manganite (NiMn2O4) powder with a pure cubic spinel phase structure was synthesized via sol-gel combustion and characterized with XRD, FT-IR, XPS and SEM. The powder was mixed with sodium alginate gel to form a nano-biocomposite gel, dried at room temperature to form a thick film and characterized with FT-IR and SEM. DC resistance and AC impedance of sensor test structures obtained by drop casting the nano-biocomposite gel onto test interdigitated PdAg electrodes on an alumina substrate were measured in the temperature range of 20–50 °C at a constant relative humidity (RH) of 50% and at room temperature (25 °C) in the RH range of 40–90%. The material constant obtained from the measured decrease in resistance with temperature was determined to be 4523 K, while the temperature sensitivity at room temperature (25 °C) was −5.09%/K. Analysis of the complex impedance plots showed a dominant influence of grains. The decrease in complex impedance with increase in temperature confirmed the negative temperature coefficient effect. The grain resistance and grain relaxation frequency were determined using an equivalent circuit. The activation energy for conduction was determined as 0.45 eV from the temperature dependence of the grain resistance according to the small polaron hopping model, while the activation energy for relaxation was 0.43 eV determined from the Arrhenius dependence of the grain relaxation frequency on temperature.

Magnetic dynamics of NiMn2O4 spinel produced by a simple aqueous sol–gel route

Polycrystalline nickel manganite was prepared by a simple sol–gel method from an aqueous solution of metal chlorides containing sorbitol as a chelating agent. X-ray diffraction and Rietveld refinement show a spinel-type crystalline structure, space group Fd3¯m, and a minor (~3%) phase of rock salt structure assigned to NiO. XPS measurement shows a typical manganite electronic structure with Mn in the oxidation states Mn2+, Mn3+, and Mn4+. The zero-field-cooled and field-cooled magnetization curves measured under low magnetic fields display irreversibility and an asymmetric hysteresis evidencing some exchange bias. Field dependent DC susceptibility above Curie temperature put into evidence a competition of short ranged ferro and antiferromagnetic interactions. AC in-phase susceptibility shows a frequency independent sharp peak at the ferromagnetic phase transition (97 K) and a broad maximum at lower temperature. These maxima show a weak frequency dependence in the out-phase component. Cole–Cole plot reveals at least two magnetic relaxation processes.

Electrospun Nickel Manganite (NiMn2O4) Nanocrystalline Fibers for Humidity and Temperature Sensing.

Nickel manganite nanocrystalline fibers were obtained by electrospinning and subsequent calcination at 400 °C. As-spun fibers were characterized by TG/DTA, Scanning Electron Microscopy and FT-IR spectroscopy analysis. X-ray diffraction and FT-IR spectroscopy analysis confirmed the formation of nickel manganite with a cubic spinel structure, while N2 physisorption at 77 K enabled determination of the BET specific surface area as 25.3 m2/g and (BJH) mesopore volume as 21.5 m2/g. The material constant (B) of the nanocrystalline nickel manganite fibers applied by drop-casting on test interdigitated electrodes on alumina substrate, dried at room temperature, was determined as 4379 K in the 20–50 °C temperature range and a temperature sensitivity of −4.95%/K at room temperature (25 °C). The change of impedance with relative humidity was monitored at 25 and 50 °C for a relative humidity (RH) change of 40 to 90% in the 42 Hzπ1 MHz frequency range. At 100 Hz and 25 °C, the sensitivity of 327.36 ± 80.12 kΩ/%RH was determined, showing that nickel manganite obtained by electrospinning has potential as a multifunctional material for combined humidity and temperature sensing.

Influence of crystallization temperature and atmosphere on the phase composition, microstructure and electrical properties of Ni–Mn–O thin films

Nickel manganite thin films were prepared by chemical solution deposition from nitrate and acetate precursors on polished alumina substrates. By variation of crystallization temperature between 650 ​°C and 900 ​°C and atmosphere during cooling of the films, the morphology, phase formation and electrical properties of the films were investigated. The electrically conductive spinel phase was formed as a main phase independent of processing conditions exhibiting NTCR characteristics. Cooling down in nitrogen atmosphere favored the decomposition of the spinel phase into nickel oxide and a spinel phase with higher manganese content, but it also reduced the resistance drift of the samples. From this finding it can be deduced that a reduced oxygen partial pressure influences defect equilibria and by that decreases cation vacancy concentration. This supports the assumption that cation redistribution by a cation vacancy diffusion mechanism is a relevant mechanism of resistance drift in such thin films.

Electrical properties and stability of low temperature annealed (Zn,Cu) co-doped (Ni,Mn)3O4 spinel thin films

ABSTRACT Toward the development of infrared (IR) detectors, nickel–manganite-based thin films were initially prepared from (Ni0.2Mn2.8–x Cu x )Cl2 (0.010 ≤ x ≤ 0.040) solutions using the liquid flow deposition (LFD) method. The influence of Cu on the negative temperature coefficient of resistance (NTCR) characteristic of the films annealed at 400°C was investigated. It was found that the incorporation of Cu can effectively enhance electrical conductivity; however, it degrades both the thermal sensitivity and stability of the nickel–manganite films. The investigation was extended by further modifying the composition with Zn. The results revealed that by co-doping Cu with a proper amount of Zn the temperature coefficient of resistance (TCR) could be tailored, while a relatively low resistivity (ρ) of the final products was retained. Specially, when 0.01 mol Zn was added to a precursor solution containing 0.025 mol Cu, the resulting specimen possessed a TCR = 2.82% K–1 and a ρ = 820 Ω (measured at RT). More importantly, compared to Zn-free films, the (Zn,Cu) co-doped compositions showed much improved electrical stability, with an aging coefficient (ΔR/R) as low as 4.6%, after aging at 150°C in air for 500 h. The results suggest that the (Zn,Cu) co–doped (Ni,Mn)3O4 thin films have a promising application in IR detectors.

Low-temperature sintered Ni\u2013Zn\u2013Co\u2013Mn\u2013O spinel oxide ceramics for multilayer NTC thermistors

The phase formation, sintering behavior and electrical properties of Ni–Co–Zn–Mn spinel NTC thermistor ceramics of the series Ni0.5ZnzCo0.5Mn2−zO4 with 0 ≤ z ≤ 1 were studied. In contrast to NiMn2O4, which exhibits limited stability in air below 730 °C and above 970 °C, the Zn–Co-substituted nickel manganite spinels are stable at T < 730 °C and decompose at Td > 900 °C, with Td increasing with decreasing Zn Content z. The samples were sintered at 900 °C with addition of 3 wt% Bi2O3 as sintering aid and densities of above 92% were achieved. The room temperature resistivity and thermistor B-constants are almost independent of composition at 0 ≤ z ≤ 0.6 and start to increase at higher Zn concentrations. A multilayer NTC thermistor was fabricated using green tapes of a spinel of composition z = 0.75, commercial Ag paste, and cofiring at 900 °C. The firing behavior, microstructure formation and electrical properties of the multilayer thermistor are reported.

A novel two-step co-precipitation approach of CuS/NiMn2O4 heterostructured nanocatalyst for enhanced visible light driven photocatalytic activity via efficient photo-induced charge separation properties

A facile two-step approach of copper sulfide (CuS)/nickel manganite (NiMn2O4) heterostructure nanocomposites (NCs) were developed effectively via a simple co-precipitation method. The structural, optical, and photocatalytic behavior of the prepared NiMn2O4, CuS, and CuS/NiMn2O4 photocatalysts are carefully explored. The photocatalytic degradation efficiency of CuS/NiMn2O4 nanocatalyst was calculated to be 84% and 60% for MB and RhB, respectively, within 120 min illumination whereas the pure NiMn2O4 has 41% and 30% as well as CuS has 59% and 42% for MB and RhB. The as-prepared CuS/NiMn2O4 heterostructure has exhibited superior photocatalytic performance towards the reduction of methylene blue (MB) and rhodamine B (RhB) dyes under active visible light illumination. Thus the result showed an efficient photocatalytic activity with a high reaction kinetic rate has been achieved from the developed CuS/NiMn2O4 heterostructure catalyst due to their effective charge separation of photo-induced carriers and successful exploitation of visible light absorption.

High performance electrospun nickel manganite on carbon nanofibers electrode for vanadium redox flow battery

A composite material based on nickel manganite and carbon nanofibers (NiMn2O4/CNF) is synthesized by electrospinning method and investigated as a symmetric electrode for vanadium redox flow battery (VRFB). The X-ray diffraction pattern shows the formation of NiMn2O4/CNF, characterized by a cubic spinel-type structure and a high graphitization degree of the carbon nanofiber. XPS analysis reveals the presence of mixed oxidation state of nickel and manganese as Ni2+/Ni3+ and Mn2+/Mn3+, respectively. As evident by scanning electron microscope analysis (SEM), a complete covering of carbon nanofibers surface by NiMn2O4 nanoparticles occurs. Charge-discharge curves are carried out from 80 mA/cm2 up to 500 mA/cm2. The best result shows an energy efficiency (EE) of about 68% with corresponding deep of discharge (DoD) of about 55% at 500 mA/cm2. The high electrical conductivity as well as the high hydrophilicity, useful for improving the active surface area utilization, could be responsible for the remarkable results of the electrospun electrodes. In fact, thanks to the structural defects of the NiMn2O4/CNF and the presence of hydroxyl (OH), carboxyl (COOH) and nitrogen functional groups, the electrocatalytic activity increases at the electrode/electrolyte interface. Therefore, a remarkable power density at very high current density was achieved, 550 mW/cm2 at 500 mA/cm2.

Aging characteristic of Cu-doped nickel manganite NTC ceramics

The drift in electrical properties (e. g., the resistivity and B-value) is vital to the practical application for negative temperature coefficient (NTC) ceramics. In this work, Cu-doped nickel manganite ceramics were prepared by solid-state method, to investigate the degradation mechanism of both the resistivity and B-value. Results showed that the as-prepared ceramics exhibited typical NTC characteristics with cubic spinel phase, and that Cu doping greatly reduced the resistivity and B-value. However, the increase of Cu content in system aggravated the drift in the resistivity and B-value after the samples were aged at 300 °C for 30 h. XPS was carried out to further clarify the change in electrical properties. It was found that the decline of properties was due to the decrease of Mn4+ content in system after aging, which derived from the increase of chemical valence of Cu.