Lanthanum Nickel Research Articles

Efficient Thermal Processes Using Alternating Electromagnetic Field for Methodical and Selective Release of Hydrogen Isotopes

The controlled and selective release of hydrogen isotopes from lanthanum–nickel–aluminum (LANA) materials was achieved using an alternating electromagnetic field (AEMF). In the presence of the AEMF...

Investigation of Microwave and Thermal Processing of Electrode Material of End-of-Life Ni-MH Battery

Ni-metal hydride (NiMH) batteries should be recycled, as they contain base metals (Ni, Co) and rare earth elements (La, Ce). In this study, thermal and microwave treatments are investigated as a pre-treatment method for decomposing electrode material (Ni(OH)2 and LaNi5). The kinetic analysis of thermal decomposition electrode material yields the activation energy of 41.3 kJ/mol. The maximum percentage of lanthanum nickel oxide phase and cerium oxide phase is obtained at 1000°C of thermal treatment and 15 min of microwave exposure. The formation of melted balls of Ni and its oxide (Ni ~ 72.8%) was observed in microwave exposure, and the tendency of ball formation decreased with increasing exposure time. The effect of microwave exposure and thermal treatment on the acid leaching (1 M HCl, at S/L-1:20, at 70°C for 2 h) was studied. The leaching results showed NiO and CeO2 phases in the leach residue of thermal and microwave treated products.

Multiple perovskite layered lanthanum nickelate Ruddlesden-Popper systems as highly active bifunctional oxygen catalysts

A systematic study of the Ruddlesden-Popper structured Lan+1NinO3n+1 (n = 1, 2, 3, and 4) and its catalytic performance in oxygen evolution (OER) and oxygen reduction reactions (ORR) is carried out with a view to design a highly-efficient and cost-effective electrocatalyst. In particular, we introduce for the first time a novel La5Ni4O13-δ with a 4-layered perovskite structure (n = 4) for use as a highly active and durable bifunctional oxygen catalyst for OER/ORR. Concretely, La5Ni4O13-δ catalysts has demonstrated performance of 1.65 V at 10 mA·cm−2 and 0.66 V at near half-wave potential (–3 mA·cm−2) for OER and ORR, respectively, this indicates excellent intrinsic OER/ORR kinetics. Furthermore, by controlling the fuel-to-oxidizer ratio (using extremely fuel-rich conditions) in the glycine-nitrate combustion technique, the 4-layered perovskite La5Ni4O13-δ catalysts are synthesized as a single Ruddlesden–Popper phase with various dopants to further boost its bifunctional oxygen electrode activity. Among OER/ORR catalysts, La5Ni3CoO13-δ catalysts exhibit exceptional electrocatalytic activity with low overpotential and Tafel slope (35/76 mV‧dec-1 for OER/ORR). Outstandingly, the La5Ni3CoO13-δ is able to achieve an extremely low overpotential of 370 mV at 10 mA‧cm−2 in 0.1 M KOH for OER, surpassing Ir/C catalysts and any metal oxide catalyst ever reported. The high catalytic performance of La5Ni3CoO13-δ can be attributed to its favorable electronic structure enriched with oxygen defects and electronic charge carriers (increased Ni oxidation state) as well as to the promoted lattice-oxygen oxidation mechanism pathway that comes from strong metal–oxygen covalency (high oxygen-ion diffusion rate).

(Ba/Pb)xSr1−xTiO3 based capacitive sensor with LaNiO3 electrode for higher tunability

The high tunability range of capacitive sensors can be achieved by the use of ferroelectric materials due to its perovskite structure. Thin films provide better utilization of properties comparative to bulk but greatly affect by the surface on which it deposited. In this work thin films of BaxSr1−xTiO3 (BST) and PbxSr1−xTiO3 (PST) are developed with x = 0.3 & 0.7. Thin films without doping of Sr are also developed for comparison. The capacitors Al/Si/BST/Al and Al/Si/PST/Al are fabricated in parallel plate structure using the sol–gel processing technique with Al as metal electrodes and BST/PST as the dielectric material. A new parallel plate capacitor with the introduction of Lanthanum Nickel Oxide (LNO) thin film with the preferred (100) orientation between Si substrate and BST/PST is proposed in this work. Crystallinity and orientation of BST/PST on Si and BST/PST over LNO are observed by X-ray diffraction (XRD). The average grain size and uniformity of thin films are confirmed by scanning electron microscopy (SEM) images. The capacitances are measured at 50 mV and 70 mV using LCR meter. The highest capacitance of 79.6pF is observed for Al/Si/LNO/BST/Al. Impedance spectroscopy reveals the decrement in impedance with doping of Sr and tunability range of LNO based BST/PST capacitor is much higher compared to non-LNO capacitors. Tunability with BST material reaches 57% at frequency 2.98 kHz and the PST attains a value of 33.8% at frequency 1.44 KHz.

Structure, thermal expansion and electrical conductivity of La2–xGdxNiO4+δ (0.0 ≤x≤ 0.6) cathode materials for SOFC applications

A new series of La2–xGdxNiO4+δ (0.0 ≤ x ≤ 0.6) synthesized via formate pyrolysis were tested as potential cathode materials for intermediate solid oxide fuel cells (IT-SOFCs). It was found that the materials are single-phase up to x = 0.5 and crystallize in a tetragonal structure (I4/mmm space group). They show superior oxygen over-stoichiometry values, δ, to those of both the undoped lanthanum nickelate and the one doped with alkali-earth elements. To satisfy the requirements for the increased efficiency and durability of SOFCs, chemical and thermo-mechanical compatibility between the cathode materials developed and a Ce0.8Gd0.2O1.9 solid-state electrolyte was studied. Concentration dependences of electrical and thermal properties of the La2–xGdxNiO4+δ compounds were discussed in interrelation with their structural peculiarities and the temperature behavior of δ.

Non-linear temperature dependent phononic response of epitaxial lanthanum nickelate thin film

From the temperature dependent Raman spectroscopy study (80 K–300 K) on epitaxial thin film of lanthanum nickelate (LNO), we find that the characteristics Raman active phonon modes (A1g and Eg) of LNO soften with an increase in the temperature. The extent of softening is greater for the A1g mode owing to substrate induced strain. In addition, temperature dependent Raman shifts presented with some non-linearities. Our analysis suggests that these non linearities arise due to an anharmonic contribution to the Raman shifts. We find that for A1g mode, four-phonon anharmonic process contributed most to the temperature dependent Raman shifts, while the contributions from three-phonon, strain and thermal expansion effect found to be relatively small. However, for Eg mode, the shift originated mainly from the thermal expansion effect.

Ultrasonic‐Assisted Preparation Of Perovskite‐Type Lanthanum Nickelate Nanostructures and Its Photocatalytic Properties

AbstractIn the present investigation, the perovskite‐type Lanthanum Nickelate (LaNiO3, LNO) nanostructure samples with the incompatible surface morphology were successfully synthesized by a single step ultrasonication processes followed by annealing at various temperatures in the range of 500–800 °C. The phase identification and chemical composition of the perovskite‐type LaNiO3 nanostructure was inspected by powder X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). Besides, the physical and chemical techniques such as Fourier transform infrared spectroscopy (FT‐IR), UV‐Vis diffuse reflectance (UV‐vis DRS) studies, and microscopic studies (SEM and TEM) revealed the nature of the LNO samples. Moreover, as a result of calcination and phase transformation, a significant comparative bandgap around 1.78‐2.12 eV observed, which was fascinating to examine their visible photons induced photocatalytic degradation of Orange‐G azo dye (OG). The impact of various experimental circumstances inclusive of initial dye concentration, catalyst amount, pH of the reaction medium, and the effect of different oxidants was optimized. Under the optimum context, the photodegradation efficiency of the OG dye with LNO‐800 was 96 % whereas LNO‐800 with oxidant peoxodisulphate (PDS) shows 98 % activity within the 240 min and 150 min, respectively. After each photocatalytic experiment, photocatalyst samples can be effortlessly separated from the reaction mixture and shows almost equivalent photocatalytic effectiveness after multiple cycles intimated the superior photostability of LNO samples.

Charge reactions on crystalline/amorphous lanthanum nickel oxide cocatalyst modified hematite photoanode.

Understanding the charge reactions at the semiconductor/cocatalyst interface is of great interest for boosting photoelectrochemical water splitting since the charge transfer to water molecules is the sluggish one. Besides the dopants, porosity, or ion-penetration of the cocatalyst, the crystallinity of the cocatalyst may also influence the charge reactions at the interface. Herein, we prepared amorphous LaNiOx and crystalline La-doped NiO (c-LaNiOx) cocatalysts through photochemical decomposition and ion-exchange of Ni(OH)2 precipitation, respectively. Both lanthanum nickel oxides (LaNiOx) showed considerable improvement of hematite photoanodes. By using electrochemical impedance measurements, we confirmed that the catalyst could store photogenerated charges with reduced transfer resistance and passivate the surface state, resulting in the overall charge transfer rate enhancement. This study may lead to a chance to uncover the kinetic bottleneck with an efficient cocatalyst in well-controlled crystallinity in the future.

Voltammetry study of electrocatalytic activity of lanthanum nickel perovskite nanoclusters-based composite catalyst for effective oxidation of urea in alkaline medium

Effective electrooxidation of urea has been the focus of research and development for energy and environmental applications. A modified glassy carbon (GC) electrode with two successive layers of conducting poly(aniline) (PANI) and lanthanum nickel oxide (LNO)-graphene oxide (GO) mixture was fabricated for urea electrooxidation in alkaline medium. Different conditions of catalyst preparation were examined for optimum electrocatalytic activity towards urea oxidation. GO improved the response and is considered advantageous support for the perovskite due to its structural and electronic differences compared to graphene (G). The highest electrocatalytic activity observed was for non-calcinated perovskite catalyst prepared by citric acid fuel and physically mixed with GO in the ratio (1:2). The use of La2NiO4 perovskite is beneficial with relatively low weight percentage of Ni (14.6 %) compared to other Ni-based catalysts for electrooxidation of urea. The perovskite catalyst is synthesized using microwave-assisted method that reduces chemicals usage and energy consumption. The non-calcinated perovskite catalyst and the (PANI/LNO-GO) composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive analysis (SEM-EDAX). The composite is applicable in temperature range (10 °C up to 50 °C), and at different urea concentrations from 0.1 M to 1.0 M in basic (KOH) electrolyte.

Performance Restoration of a Tritium-Aged LaNi4.25Al0.75 Sample

Hydride beds containing LaNi4.25Al0.75 (LANA.75) are used to store significant quantities of tritium. These hydride beds have a limited service life due to radiolytic decay of tritium to 3He within the metal matrix. The crystal structure of the hydride is altered by trapped 3He, which has a very low solubility in the metal. The altered structure induces the formation of a heel of trapped hydrogen isotopes and diminishes the reversible capacity of the hydride. With sufficient tritium exposure, the bed loses the ability to deliver 3He-free tritium, and replacement is needed. Demonstration of a means to regenerate tritium-aged LANA.75 in situ would delay or even eliminate the need to replace lanthanum nickel aluminum (LANA) hydride beds. This paper presents test results obtained during regeneration testing. The efficacy of regeneration testing was evaluated by comparing tritium desorption isotherms collected on the hydride before and after exposure to regeneration conditions. Testing was performed on a bench-scale tritium-aged LANA.75 sample that was previously isotopically exchanged (from tritium to deuterium), passivated, and recovered. Once transferred to a high-temperature test cell, the deuterium heel of the sample was isotopically exchanged with tritium, and a baseline desorption isotherm was collected for comparison purposes. The sample was then heated under vacuum, and comparative isotherms were gathered between regeneration evolutions. Shifts in isotherms show progressive improvements with higher-temperature exposure over the tritium-aged baseline. The heel was significantly reduced, and the reversible capacity of the hydride was essentially restored to near virgin values. For all tested conditions, the plateau pressure remained higher than virgin LANA.75.

Oxygen nonstoichiometry and electrical properties of La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5)

The amount of interstitial oxygen (δ) in Sr-doped lanthanum nickel oxide (La2–xSrxNiO4+δ) as a function of Sr content has been investigated by the thermogravimetry analysis (TGA) and X-ray photoelectron spectroscopy (XPS). La2–xSrxNiO4+δ (0 ≤ x ≤ 0.5) ceramics were prepared by the general solid-state reaction process and sintered in different ambient of argon, air or oxygen, respectively. An increase in the amount of Sr decreased δ in La2–xSrxNiO4+δ, while the Ni2+/Ni3+ ratio analyzed by Ni3p XPS decreased indicating that the oxidation state of Ni increased. Particularly when the sample was sintered in a low oxygen partial pressure condition such as in Ar ambient, the hole concentration strongly depended on the Sr content, suggesting that the hole generation seems mostly originated from Sr2+ substitution into the La3+ site.

Anisotropy of core-level spectra and the correlation with transport properties of epitaxial lanthanum nickel oxide thin films

We studied the electronic structures of (001), (110), and (111) LaNiO3 (LNO) films using XPS. Core-level photoemission spectra analysis reveals that the energy separation ΔE from the satellite to main peaks of Ni 2p1/2 clearly varies in accordance with LNO film orientation. The ΔE in (111) LNO films is 9.71 ± 0.1 eV, larger than the values of 9.39 ± 0.1 and 9.21 ± 0.1 eV in corresponding (001) and (110) films, respectively. This indicates that the Ni 3d–O 2p hopping interaction strength tpd is larger in the (111) LNO films compared with the other two films. The large aforementioned tpd in (111) LNO films also changes the electron states near the Fermi level, which suggests improved electrical conductive properties in (111) LNO films compared with corresponding (110) and (001) films.

Structural, morphological and magnetic properties of strontium substituted lanthanum nickelate La2−xSrxNiO4 (0 ≤ x ≤ 0.5)

Employing the standard reaction method, partially strontium substituted lanthanum nickelate Bulk La2−xSrxNiO4 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) materials have been prepared by solid-state reaction method. The gross structure and phase purity of La2−xSrxNiO4 materials were examined by powder X-ray diffraction (XRD) technique. The X-ray diffraction patterns indicate that the structure phase of La2−xSrxNiO4 does not change by the addition of strontium up to x = 0.5. The XRD results show the formation of single tetragonal phase. The average crystallite/grain sizes of the La2−xSrxNiO4 samples were calculated by using Debye-Scherer formula. The magnetic measurement was observed by (M−H) curve, the surface morphology/topography of as-synthesized materials (pellets) was determined by Atomic Force Microscope (AFM) Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscopic analysis (TEM). The AFM and FESEM micrographs show many porous which closely packed themselves. These micrographs also reveal that the increase the strontium concentration in the materials, the grain size of La2−xSrxNiO4 also increases.

Spectroscopic and Antimicrobial Examine on LaNi1-xFexO3 (x = 0.1 & 0.2) Nanoparticles Synthesized By Sol Gel Combustion Method

Most of the perovskite materials exhibit an anti- bacterial effect, and due to their non-toxic nature they can be used in surgical tools. An attempt has been made to study the anti-bacterial activity and its spectroscopic analysis of Fe- doped Lanthanum Nickel Oxide nanoparticles prepared by sol-gel combustion method. The material exhibits cubic structure of LaNi1-xFexO3 examined from XRD analysis. The optical absorbance, bandgap and the type of bonding have been identified using UV-VIS spectroscopic and FT-IR analysis. Antibacterial property of the synthesized material also studied using a gram positive bacteria (Streptococcus pyogenes ) and gram negative bacteria (Escherichia coli ).

Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO3 Layer.

In this study, a novel metal oxide, lanthanum nickelate (LNO) with a perovskite structure, was introduced into a polymer solar cell (PSC) device, replacing the PEDOT:PSS hole transport layer (HTL). The results show that the LNO-based PTB7-Th:PC71BM solar cell exhibits a higher circuit current density, power conversion efficiency, and stability compared with a device with PEDOT:PSS HTL. To understand the effect of LNO HTL on the performance of devices, the active layer morphology and charge transport characteristics in PSCs were systematically analyzed. The morphology of active layer was affected by the HTL, which further regulated the generation and transport processes of charge carrier in the PSC device. For the LNO HTL, an appropriate thickness (8 nm) and a small surface roughness (Sq = 0.7 nm) can coordinate the energy-level structure of device and improve the interface contact between the FTO electrode and PTB7-Th:PC71BM active layer, promoting the charge transport performance of device. Therefore, this work provides a new consideration for the preparation of efficient, stable, and low-cost polymer solar cells.

Lanthanum nickel oxide nano-perovskite decorated carbon nanotubes/poly(aniline) composite for effective electrochemical oxidation of urea

Here in, we introduce a modified glassy carbon (GC) electrode with two successive layers of conducting poly(aniline) (PANI) and lanthanum nickel oxide (LNO)-carbon nanotubes (CNT) mixture, (GC/PANI/LNO-CNT), for urea electrooxidation in alkaline medium. The use of La2NiO4 perovskite is advantageous with relatively low weight percentage of Ni (14.6%) compared to other Ni-based catalysts for electrooxidation of urea. The perovskite catalyst is synthesized using microwave-assisted method that reduces chemicals and energy consumption. Perovskite-based catalyst has good ionic and electronic conducting behavior, high oxygen mobility within its lattice with remarkable charge transfer rate. Carbon nanotubes increase the surface area of the electrode and act as a catalyst support to enhance the urea conversion process. Under optimized conditions, the specific current for urea electrooxidation is 1400 mA mg−1 cm−2. The perovskite catalyst and the (PANI/LNO-CNT) composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive analysis (SEM-EDAX). The composite is applicable in temperature range (10 °C to 50 °C), and at different urea concentrations (0.1 M to 1.0 M) in basic (KOH) electrolyte.

Kalsinasyon Sıcaklığının Modifiye Edilmiş Pechini Yöntemi ile Hazırlanan Perovskit Özelliklerine Etkisi

Perovskite type oxides which have the general formula as ABO 3 including both rare earth elements and 3d transition metals is gaining interest according to be utilized as such strategic materials because of their excellent catalytic, magnetic, electrical and optical properties. Along with perovskitic materials, lanthanum nickel oxide (LaNiO 3 -LNO) shows potential as a consequence of its electronic and catalytic properties in not only reactions like reforming, redox reactions but also in storage and conversion of energy or synthesis an electrode material. LNOs are widely prepared by methods like sol-gel, co-precipitation, solid state and Pechini. Among these methods, the Pechini method uses the common metal salts consisting of nitrates, acetates, chlorides, etc. as precursors and citric acid (CA) as a chelating agent of metal ions and ethylene glycol (EG) as a cross-linking agent to form a polymeric resin on molecular level and declines segregation of metal ions and ensures compositional homogeneity. This process can defeat most of the difficulties and disadvantages that frequently occur in the alkoxides related to sol−gel method. The present work attempts to scan the effect of calcination temperature on the physical properties of LaNiO 3 catalysts prepared by modified Pechini method without ethylene glycol. In order to lay out the physical properties, X-ray diffraction (XRD), scanning energy micoscopy (SEM), and N 2 adsorption/desorption techniques were used. The change with the temperature in the structure caused a decrease in surface area, pore volume and increase in pore size. XRD studies revealed that calcination of LNO at 700°C favored the formation of an almost homogeneous LaNiO 3 perovskite phase rather than calcination at 500°C. The study underlined that the preparation of the LNO by the modified Pechini method can be applied successfully with the temperature above 700°C without EG as a cross-linking agent.

Layer Crystallization in PZT/LNO/Si Heterostructures

A Pb(Zr0.52Ti0.48)O3–LaNiO3–Si composition and LaNiO3 thin films are synthesized using chemical solution deposition and studied by transmission electron microscopy. The polycrystalline, porous structure of LaNiO3 is found to misalign the columnar structure of lead zirconate titanate. The effect that thermal treatment has on the structure and phase composition of lanthanum nickelate is addressed. The morphological features of LaNiO3 film structure such as its layered character, porosity, and misalignment are observed in samples subjected to annealing at a temperature of 550°C and are more pronounced upon raising the temperature to 800°C.

Ni–La composite coating obtained using deep eutectic solvent and its electrocatalytic activity

The overpotential of hydrogen evolution reaction is one of the aspects which results in low efficacy of water electrolysers. There is a constant search for new ways to improve the catalytic activity, especially of nickel-based materials. Addition of lanthanum results in synergism and high activity towards the hydrogen evolution reaction. Due to the application of deep eutectic solvents which are characterized by a wide electrochemical window and good solvent properties for metal ions, it was possible to deposit the lanthanum–nickel alloy coating which was composed of around 40% of La. Hydrogen evolution reaction conducted on this layer resulted in a reduction of overpotential by 129 mV in comparison to pure Ni layer at current density of 1 mA cm−2. Other kinetic parameters, such as Tafel slope and exchange current density, were also significantly improved.

Investigation of structural, optical, dielectric and magnetic properties of LaNiO3 and LaNi1−xMxO3 (M = Fe, Cr & Co; x = 5%) nanoparticles

This paper reports the synthesis of pure and doped lanthanum nickel oxide (LaNiO3) nanoparticles (NPs) using auto-combustion route. Various characterization techniques were employed for the investigation of the effect of transition metal doping on the structural, optical, magnetic and frequency dependent dielectric properties of this system. X-ray diffraction (XRD) results were used to calculate the crystallite size and phase composition of the nanoparticles. The well intense peaks in the XRD pattern confirmed the perfect doping of transition metal ions (Fe, Cr, Co) in the LaNiO3 lattice structure. The scanning electron microscopy (SEM) confirmed the porous surface morphology of the nanoparticles. The presence of various functional groups, stretching and vibrational modes were analyzed by the Fourier Transform Infra-Red (FTIR) technique. The energy band gap (Eg) of the synthesized materials were calculated from the absorbance spectra using Tauc’s relation. The band gap was observed to increase with doping indicating blue shift. The frequency dependent dielectric properties were measured at room temperature using LCR meter in the frequency range of 42 Hz to 5 MHz. It was observed that the dielectric constant and dielectric loss decreases with the increase in frequency. This decrease in dielectric constant as well as in dielectric loss with increase in frequency may be attributed to decreased polarization at higher frequency. The dielectric behaviour of LaNiO3 based perovskite oxides is explained on the basis of Koop’s theory which is based on Maxwell-Wagner two layer model. Vibrating sample magnetometer (VSM) was used to study the magnetic properties at room temperature and the obtained results confirmed the ferromagnetic nature of all the compositions.