Showing papers on "Lanthanum published in 2022"

Lanthanum nitrate as aqueous electrolyte additive for favourable zinc metal electrodeposition

Abstract: Aqueous zinc batteries are appealing devices for cost-effective and environmentally sustainable energy storage. However, the zinc metal deposition at the anode strongly influences the battery cycle life and performance. To circumvent this issue, here we propose the use of lanthanum nitrate (La(NO3)3) as supporting salt for aqueous zinc sulfate (ZnSO4) electrolyte solutions. Via physicochemical and electrochemical characterizations, we demonstrate that this peculiar electrolyte formulation weakens the electric double layer repulsive force, thus, favouring dense metallic zinc deposits and regulating the charge distribution at the zinc metal|electrolyte interface. When tested in Zn||VS2 full coin cell configuration (with cathode mass loading of 16 mg cm-2), the electrolyte solution containing the lanthanum ions enables almost 1000 cycles at 1 A g-1 (after 5 activation cycles at 0.05 A g-1) with a stable discharge capacity of about 90 mAh g-1 and an average cell discharge voltage of ∼0.54 V.

Adsorption of lanthanum and cerium on chelating ion exchange resins: kinetic and thermodynamic studies

Abstract: As the demand for rare earth elements (REE) increases in the coming years, techniques to obtain these elements from different sources may be explored. A hydrometallurgical route may achieve the sus...

Lanthanum substitution effect on the structural, optical, and dielectrical properties of nanocrystalline BaFe2O4 ferrites

Abstract: The effects of varying the amount of lanthanum infusion on the barium ferrite characteristics were investigated in this study. An orthorhombic structure formed as a majority phase and traces of barium lanthanum iron oxide as segregated phases in the ferrites composites. The optical bandgap energy values of the BaLaxFe2−xO4 nanoferrites were 3.50–3.72 eV. SEM confirmed that the prepared nanoferrites had spherical morphology with size of 66.50–81.50 nm. The dielectric parameters of BaLaxFe2−xO4 nanoferrites were studied in the specified spectrum, which revealed the La doped barium nanoferrites had a low dielectric constant and conductivity properties compared to the barium nanoferrites. The saturation magnetization (60.03–25.98 emu g−1) and coercivity (454.85–80.65 Oe) of the prepared nanoferrites were improved due to an effect of La3+ ions. Accordingly, the observed optical bandgap energy, dielectric constant, and magnetism could be employed in high-frequency magneto-optoelectronic systems.

In situ grown rare earth lanthanum on carbon nanofibre for interfacial reinforcement in Zn implants

Abstract: ABSTRACT Carbon nanofibre (CNF) is a potential reinforcement in Zn implants. Nevertheless, its poor interfacial compatibility reduces the reinforcement efficiency drastically. In this study, rare earth lanthanum (La) was used as a compatible interface layer between CNF and Zn matrix. On the one hand, La in situ grew on acidified CNF by a chemical synthesis and achieved a firm coordination covalent bond with the oxygenated functional group derived from CNF. On the other hand, La, as an active rare earth element, could carry out the alloying reaction with the Zn matrix, thus forming strong metal bonding. Results showed that the tensile strength of composites was enhanced from 180.2 ± 12.1 to 243.4 ± 10.2 MPa since the La interface layer promoted the transfer of the interfacial shear stress from the Zn matrix to CNF and thereby consumed massive fracture energy. Encouragingly, it simultaneously improved the ductility, as La activated basal slip and improved the dislocation accommodation capacity. Moreover, the Zn implants displayed excellent anti-tumour efficiency.

First-principles search of hot superconductivity in La-X-H ternary hydrides

Abstract: Abstract Motivated by the recent claim of hot superconductivity with critical temperatures up to 550 K in La + x hydrides, we investigate the high-pressure phase diagram of compounds that may have formed in the experiment, using first-principles calculations for evolutionary crystal structure prediction and superconductivity. Starting from the hypothesis that the observed T c may be realized by successive heating upon a pre-formed LaH 10 phase, we examine plausible ternaries of lanthanum, hydrogen and other elements present in the diamond anvil cell: boron, nitrogen, carbon, platinum, gallium, gold. We find that only boron and, to a lesser extent, gallium form metastable superhydride-like structures that can host high- T c superconductivity, but the predicted T c ’s are incompatible with the experimental reports. Our results indicate that, while the claims of hot superconductivity should be reconsidered, it is very likely that unknown H-rich ternary or multinary phases containing lanthanum, hydrogen, and possibly boron or gallium may have formed under the reported experimental conditions, and that these may exhibit superconducting properties comparable, or even superior, to those of currently known hydrides.

Removal of lead ions from wastewater using lanthanum sulfide nanoparticle decorated over magnetic graphene oxide

Abstract: In this study, the new lanthanum sulfide nanoparticle (La2S3) was synthesized and incorporated onto magnetic graphene oxide (MGO) sheets surface to produce potential adsorbent (MGO@LaS) for efficient removal of lead ions (Pb2+) from wastewater. The synthesized MGO@LaS adsorbent was characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The effective parameters on the adsorption process including solution pH (~5), adsorbent dosage (20 mg), contact time (40 min), initial Pb2+ concentration and temperature were studied. The removal efficiency was obtained >95% for lead ions at pH 5 with 20 mg adsorbent. To validate the adsorption rate and mechanism, the kinetic and thermodynamic models were studied based on experimental data. The Langmuir isotherm model was best fitted to initial equilibrium concentration with a maximum adsorption capacity of 123.46 mg/g. This indicated a monolayer adsorption pattern for Pb2+ ions over MGO@LaS. The pseudo-second-order as the kinetic model was best fitted to describe the adsorption rate due to high R2 > 0.999 as compared first-order. A thermodynamic model suggested a chemisorption and physisorption adsorption mechanism for Pb2+ ions uptake into MGO@LaS at different temperatures; ΔG° < -5.99 kJ mol-1 at 20 °C and ΔG° -18.2 kJ mol-1 at 45 °C. The obtained results showed that the novel nanocomposite (MGO@LaS) can be used as an alternative adsorbent in wastewater treatment.

Room-Temperature Fast H- Conduction in Oxygen-Substituted Lanthanum Hydride.

Abstract: The hydride ion (H-) is a unique anionic species that exhibits high reactivity and chemical energy. H- conductors are key materials to utilize advantages of H- for applications, such as chemical reactors and energy storage systems. However, low H- conductivity at room temperature (RT) in current H- conductors limit their applications. In this study, we report a H- conductivity of ∼1 mS cm-1 at RT, which is higher by 3 orders of magnitude than that of the best conductor, in lightly oxygen-doped lanthanum hydride, LaH3-2xOx with x < 0.25. The oxygen concentration (x) is crucial in achieving fast H- conduction near RT; the low activation barrier of 0.3-0.4 eV is attained for x < 0.25, above which it increases to 1.2-1.3 eV. Molecular dynamics simulations using neural-network potential successfully reproduced the observed activation energy, revealing the presence of mobile and immobile H-.

Selective adsorption behavior and mechanism of phosphate in water by different lanthanum modified biochar

Abstract: Lanthanum-based adsorbents are promising phosphate (P) adsorbents and their selectivity determines their potential for application in P recovery. However, there have been few systematic studies for quantifying the selectivity of lanthanum-based adsorbents for P. In this study, lanthanum carbonate/biochar (LCB300) and lanthanum hydroxide/biochar (LHB800) composites were synthesized to quantify their selectivity for P adsorption. Batch adsorption experiments were conducted to investigate the influence of environmental factors on their selectivity. The results showed that both LCB300 and LHB800 exhibit similar maximum adsorption capacities for P (64.3 and 65.0 mg g−1, respectively). However, the selectivity of LHB800 (90–100%) for P was higher than that of LCB300 (73–99%), and the former was less susceptible to environmental conditions than the latter. In addition, competing ions accelerated the intermediate process of P adsorption by LHB800, but slightly inhibited the adsorption rate of LCB300 for P. These results show that the form of lanthanum on the adsorbent affects its adsorption mechanism and corresponding selectivity for P. Moreover, LHB800 demonstrates significant potential for application in the recovery of phosphate from wastewater.

Recent Progress in the Design, Characterisation and Application of LaAlO3- and LaGaO3-Based Solid Oxide Fuel Cell Electrolytes

Abstract: Solid oxide fuel cells (SOFCs) are efficient electrochemical devices that allow for the direct conversion of fuels (their chemical energy) into electricity. Although conventional SOFCs based on YSZ electrolytes are widely used from laboratory to commercial scales, the development of alternative ion-conducting electrolytes is of great importance for improving SOFC performance at reduced operation temperatures. The review summarizes the basic information on two representative families of oxygen-conducting electrolytes: doped lanthanum aluminates (LaAlO3) and lanthanum gallates (LaGaO3). Their preparation features, chemical stability, thermal behaviour and transport properties are thoroughly analyzed in terms of their connection with the target functional parameters of related SOFCs. The data presented here will serve as a starting point for further studies of La-based perovskites, including in the fields of solid state ionics, electrochemistry and applied energy.

Tailoring high-temperature stability and electrical conductivity of high entropy lanthanum manganite for solid oxide fuel cell cathodes

Abstract: Optimum (La 0.2 Nd 0.2 Sm 0.2 Ca 0.2 Sr 0.2 )MnO 3 exhibits excellent high-temperature resistance to elemental segregation and chemical compatibility with 8YSZ while maintaining good electrical conductivity.

N-doped LaPO4: An effective Pt-free catalyst for electrocatalytic oxygen reduction

Abstract: This work provides a novel rare-earth-based catalyst of N-regulated lanthanum phosphate (N-LaPO4/C) and the corresponding rational measurement of catalytic activity for the oxygen reduction reaction (ORR). Developed N-LaPO4/C displays more positive half-wave potential (0.88 V) and onset potential (1.02 V) for the ORR, surpassing commercial Pt/C (0.96 and 0.85 V) and most reported research works. The robust stability of N-LaPO4/C for the ORR is also demonstrated. Comprehensive analyses through X-ray absorption spectroscopy, surface Pourbaix diagram, microkinetic modeling, and data mining based on an advanced explainable machine learning demonstrate a self-oxidation process on LaPO4 during the alkaline ORR and identify the key role of N in LaPO4 in promoting ORR. N-doped LaPO4 in N-LaPO4/C is found to be an active center. Further findings show that N-LaPO4/C + RuO2 can be applied in rechargeable Zn-air batteries as an air cathode, showing a good power density and a long cycle life.