Effect Of La Doping Research Articles

Improved photocatalytic properties of WO3 nanoparticles for Malachite green dye degradation under visible light irradiation: An effect of La doping

Abstract Doped materials have received substantial attention due to their increased usefulness in photocatalytic applications. Within this context, the present study was dedicated to investigating the potential of the precipitation technique for producing La-doped tungsten oxide (WO3). To comprehensively characterize the synthesized La-doped WO3, scanning electron microscopy and X-ray diffraction were judiciously employed. The focal point of the investigation encompassed an examination of the impact of varying La concentrations on multiple fronts: the photocatalytic activities (PCAs), as well as any associated structural and morphological modifications. This holistic approach aimed to uncover the intricate relationship between La incorporation and the resulting properties of the WO3 matrix. Through the degradation of Malachite green dye within an aqueous medium, PCA of the La-doped WO3 samples was quantitatively evaluated. Remarkably, over 180 min under irradiation of visible light irradiation, the achieved levels of dye degradation were remarkable, amounting to 81.165, 83.11, and 83.85% for the respective samples. These findings firmly underscore the potential of La-doped WO3 as a proficient photocatalyst, particularly in color removal from wastewater. This study paves the way for enhanced wastewater treatment approaches by utilizing doped WO3 materials.

Synergistic effects of La-doping on ZnO nanostructured photocatalysts for enhanced MB dye degradation

In this work, we present the design and characterization of pristine and La-doped ZnO photocatalysts, prepared via a facile co-precipitation technique. A comprehensive range of characterization techniques was employed to analyze the physicochemical properties of these synthesized nanostructured photocatalysts. The slight shift in the position of peaks in the X-ray diffraction (XRD) pattern confirms successful doping (La3+) of ZnO. Additionally, the identified wurtzite phase further validates the presence of ZnO nanostructures. Subsequent photocatalytic investigations were conducted using model solutions of water and methylene blue (MB) dyes under solar irradiation, meticulously comparing the performance of pure ZnO with La3+ doped ZnO. Over the time span of 90 min, the 5 % La-doped ZnO photocatalysts exhibited an impressive 98 % degradation efficiency for MB dye, surpassing the performance of the pristine ZnO counterpart (0 % La), which achieved only 51 % degradation. This emphasizes the pronounced enhancement resulting from the incorporation of La ions. The photoluminescence (PL) spectra insights with 5 % La3+doping exhibit significant quenching, caused by the suppression of charge carrier recombination, which enhances the photocatalyst's charge transport. X-ray photoelectron spectroscopy (XPS) spectra provided crucial insights into the elemental composition and chemical states of the 5 % La3+ doped ZnO nanostructures. Through systematic reusability assessments, it was established that the 5 % La-doped ZnO photocatalysts maintain their efficiency for up to four cycles, without displaying a significant reduction in removal efficacy. This emphasizes the inherent reliability and robustness of the developed photocatalysts.

Go-encapsulated La-doped lithium manganese oxide assemblies to enhance lithium extraction performance in capacitive deionization

The electrochemical lithium extraction technique from brine has emerged as a key strategy in addressing the issue of lithium resource scarcity. Lithium manganese oxide (LMO) stands out as a typical lithium-ion selective material. Nevertheless, its lithium extraction application is restricted by inadequate conductivity and limited cycling stability. In this report, through a simple electrostatic self-assembling method, a 3-dimensional (3D) GO/La-LMO hybrid was fabricated wherein La-doped LMO (La-LMO) was enveloped by graphene oxide (GO) nanosheets. The resultant GO/La-LMO exhibited a significantly improved electrochemical behavior with fast Li+ diffusion rate and high conductivity. The GO/La-LMO hybrid demonstrated outstanding selectivity for the electrochemical intercalation/de-intercalation of Li+. As a Li+-selective cathode in capacitive deionization (CDI) device, the GO/La-LMO electrode achieved a high Li+ adsorption capacity of 1.33 mmol g−1 (10 mM LiCl) and superior selectivity with a separation factor of 126 (Mg2+/Li+ = 30, molar ratio) in Mg2+/Li+ mixed solution. The Li+ extraction percentage reached 80.4 % in the simulated salt-lake brine. Crucially, the GO/La-LMO electrode substantiated prominent structural stability and low Mn dissolution over 100 cycles, attributed to the synergistic effect of La-doping and GO capsulation to mitigate Jahn-Teller distortion. In addition, the selective adsorption–desorption mechanism of Li+ was confirmed. This work introduces a facile approach for the fabrication of robust carbon-based LMO hybrids, demonstrating the potential applications as high-performance lithium-selective materials.

Balancing the Ion/Electron Transport of Graphite Anodes by a La-Doped TiNb2O7 Functional Coating for Fast-Charging Li-Ion Batteries.

A functional coating layer (FCL) is widely applied in fast-charging lithium-ion batteries to improve the sluggish Li+ transport kinetics of traditional graphite anodes. However, blindly increasing the Li+ conductivity for FCL reduces the overall electron conductivity of the anodes. Herein, we decoupled the effect of La-doping on TiNb2O7 (TNO) in terms of the phase evolution, Li+/electron transport, and lithiation behavior, and then proposed a promising La0.1TNO FCL with balanced Li+/electron transport for a fast-charging graphite anode. By optimizing the doping concentration of La, more holes are introduced into the TNO as electron carriers without causing lattice distortion, thus maintaining the fast Li+ diffusion channel in TNO. As a result, the graphite with La0.1TNO FCL delivers an excellent capacity of 220.2 mAh g-1 (96.3% retention) after 450 cycles at 3 C, nearly twice that of the unmodified one.

La-doped Porous Fe2O3 Nanorods as Advanced Anodes for Lithium/Sodium Ion Batteries and Sulfur Host for Li-Sulfur Batteries.

Transition metal oxides are investigated as electrochemically active anodes for several years due to the merits of high specific capacity, low cost, abundant resources and controllable synthesis. But the poor cycle performances have hindered their further wide application. Herein, porous La-doped FeOOH nanorods have been synthesized through a facile hydrothermal method, which could be transformed into porous La-doped Fe2O3 (Fe2O3-La) via a simple heating process. Compared with the undoped Fe2O3, the Fe2O3-La showed larger surface area, higher specific capacities and more stable cycle performances for lithium/sodium ion batteries. In addition, as an advanced sulfur host for lithium-sulfur batteries, the Fe2O3-La also displayed much more excellent cycle and rate performances than the undoped Fe2O3. The superior electrochemical performances of the Fe2O3-La may could be attributed to the doping of La, which could induce more porous morphology and offer more reactive sites. The positive effects of La-doping for electrochemical performances of porous Fe2O3 nanorods provide novel insights for further applications of rare earth metal doping.

Effects of La doping on diffused ferroelectric phase transition, electric and dielectric properties of lead-free SrBi2Ta2O9 ceramics

Citric acid-assisted method was used to synthesize pure polycrystalline La-doped SrBi2Ta2O9 powders which were uniaxially pressed and sintered under different conditions. La doping of SrBi2Ta2O9 resulted in the shortening of Ta-O bond lengths, but increased the unit cell volume and decreased the crystallite size. The effect of sintering process on dielectric properties was studied in order to find optimal sintering conditions. Dielectric loss, measured at room temperature, increases when sintering temperature rises from 1100 to 1200?C, as well as when sintering time increases from 6 to 9 h. Thus, further investigation was performed on the sample sintered at 1100?C for 6 h. The obvious change in ?? around TC and diffusive phase transition, pronounced for the ceramics with higher La content, were characteristic of the doped ceramics. The diffused ferroelectric phase transition behaviour is caused by structural disorder at the Sr-sites (Sr, Bi and La cations) in the Bi2O2 layers and perovskite blocks. The electrical conductivity increases steadily at lower temperatures (below 200 ?C), but shows a strong temperature- and frequency-dependent trend at higher frequencies. La-doping decreases conductivity by hindering charge carriers? long-distance mobility.

Electrical performance of La-doped In2O3 thin-film transistors prepared using a solution method for low-voltage driving.

In this paper, La-doped In2O3 thin-film transistors (TFTs) were prepared by using a solution method, and the effects of La doping on the structure, surface morphology, optics, and performance of In2O3 thin films and TFTs were systematically investigated. The oxygen defects concentration decreased from 27.54% to 17.93% when La doping was increased to 10 mol%, and La served as a carrier suppressor, effectively passivating defects such as oxygen defects. In fact, the trap density at the dielectric/channel interface and within the active layer can be effectively reduced using this approach. With the increase of La concentration, the mobility of LaInO TFTs decreases gradually; the threshold voltage is shifted in the positive direction, and the TFT devices are operated in the enhanced mode. The TFT device achieved a subthreshold swing (SS) as low as 0.84 V dec-1, a mobility (μ) of 14.22 cm2 V-1 s-1, a threshold voltage (VTH) of 2.16 V, and a current switching ratio of Ion/Ioff of 105 at a low operating voltage of 1 V. Therefore, regulating the doping concentration of La can greatly enhance the performance of TFT devices, which promotes the application of such devices in high-performance, large-scale, and low-power electronic systems.

Reduce the low-frequency dielectric losses of (In0.5Nb0.5)0.05Ti0.95O2 ceramics by increasing grain boundary density and resistance

(In0.5Nb0.5)0.05Ti0.95O2 (INTO) ceramics exhibits unusual colossal permittivity properties. However, the high dielectric loss limits their practical applications. Increasing the contribution of grain boundaries to dielectric properties can reduce their dielectric loss. Therefore, La was added to increase the number of grain boundaries, while annealing was performed to improve the grain boundary resistance. The results show that La addition and annealing in air indeed reduce the grain size of INTO ceramics and low their dielectric loss due to increased grain boundary resistance. Specifically, the permittivity of annealed La-doped INTO ceramic remains at 2 × 104, and its dielectric losses are less than 0.05 from 30 Hz to 6.5 kHz, with a minimum of approximately 0.02. The dielectric loss at 1 kHz is below 0.05 from below −60 °C to about 90 °C. The effects of La-doping and annealing on INTO ceramics, as well as the origin of the colossal permittivity properties, were discussed.

Improved high-temperature sintering resistance and light alkanes oxidation activity by La modification on Co3O4 nanocatalyst

In order to improve low-temperature activity and high-temperature sintering resistance of cobalt-based catalyst in catalytic degradation of emitted light alkanes, a strategy of lanthanum modification on Co3O4 nanocrystalline is proposed in this work, aiming at efficiently degrading methane emitted from the oil and natural gas industry. The La-Co3O4 nanocatalysts were prepared by co-precipitation method, and the effects of La-doping on the structural features and catalytic activity of Co3O4 catalyst for methane oxidation were investigated. The results show that the addition of lanthanum forms a composite catalyst containing La2O3 phase and Co3O4 phase, and the interaction increases the active species, which can significantly improve the low-temperature activity of the catalyst. Among them, 5 % La-Co3O4-F catalyst shows the best catalytic activity with 48 °C decrease of the temperature of 90 % methane conversion (T90) compared with pure Co3O4. Furthermore, with thermal ageing treatment at 750 °C for 100 h, Lanthanum modification can significantly slow down the agglomeration growth and the decrease of specific surface area of cobalt oxide in long-term running, and the formation of perovskite structure (LaCoO3) on Co3O4 nanocrystal surface increases the mobility of lattice oxygen, further inhibiting the sintering deactivation of Co3O4 catalyst. The catalyst doped with 5 % La still showed better performance after thermal ageing, which is 127 °C lower than T90 of pure Co3O4. Moreover, this advantage of La doping can also be observed in the catalytic oxidation of other typical hydrocarbons such as ethane and propane. This work provides a promising strategy toward the design of advanced non-precious metal oxide catalysts for practical catalytic oxidation application with excellent high-temperature sintering resistance.

Effect of La-doping on NiO photocatalyst for enhancing photocatalytic degradation performance under visible light irradiation: DFT calculations and degradation mechanism

Effect of La-doping on NiO photocatalyst for enhancing photocatalytic degradation performance under visible light irradiation: DFT calculations and degradation mechanism

Effects of La Doping on Local Structure of Hafnium Oxide Studied by X-Ray Absorption Spectroscopy

HfO2-based films prepared by the integration of the sol-gel method and spin-coating procedure were used as the study system to investigate the influence of La doping by varying the La contents of 20, 40, 50, and 60 wt%. GIXRD, XANES, and EXAFS measurements were performed to analyze phase formation, crystal structure, and local structure of the films. The XANES data of the Hf L3 -edge show no significant difference with respect to an increase in La content, indicating a considerable stability of the hafnium ion in the +4 oxidation state. Moreover, the EXAFS spectrum shows that the coordination number of Hf4+ is seven and the Hf–O bond length is ∼2.11 Å, which additionally confirms the formation of monoclinic HfO2 structure. The contributions of the second coordination shells, which are assigned to the Hf–Hf and Hf–La bonds, become well-structured with increasing La concentration in the HfO2 structure. However, the study suggests that the La-doped concentration affects the phase transformation from monoclinic to tetragonal and finally orthorhombic phase, leading to the presence of ferroelectric materials.

Orthorhombic phase induced ultra-low operation voltage in La-doped BiFeO3 resistive switching devices

In this study, the effect of La doping on the resistive switching properties of BiFeO3 (BFO) is systematically discussed. It was found that La doping can not only inhibit the volatilization of Bi and thus diminish the intrinsic oxygen vacancy of BFO, but also improve the lattice symmetry of BFO for generating orthorhombic phase BFO. To confirm these microstructural changes and their relation to the resistive switching properties of BFO, the phase structures, chemical compositions, microstructures, energy band structures, and interfacial features of BFO with different La-doping concentrations are characterized. The resistances of BFO devices with different La doping concentrations also show significant differences, especially, the 15 at. % La-doping BFO device exhibits ultra-low operation voltage of only −0.15 V and good cycling consistency due to the integration of low oxygen vacancy concentrations and precipitation of the orthorhombic phase. The multiple effects of La doping on the resistive characteristics of BFO discussed in this paper provide a reference for the application of BFO in the field of resistive memories.

Understanding improved thermal stability of lanthanum-modified Cu/CeO2-ZrO2 for CO oxidation under lean-burn exhaust conditions

Rigorous emission regulations and the advancements in combustion engines have forced researchers to develop new strategies for removing CO at low temperatures. The Cu/CeO2-ZrO2 (Cu/CZ) catalyst has received an extensive attention due to its low cost and high CO oxidation activity at low temperatures. Nonetheless, the poor thermal stability of Cu/CZ remains as a major challenge for practical applications. In this study, we systematically investigated the effect of La doping on the hydrothermal stability of Cu/CZ. The La-doped catalyst, Cu/CZL, retained a high CO oxidation ability even after thermal aging at 800 °C for 20 h. La doping not only helped preserve the surface-active oxygen and oxygen storage capacity of Cu/CZ during thermal aging, but also enhanced its ability to efficiently convert intermediate surface carbonate species into CO2. These promoting effects of La resulted in the excellent CO oxidation activity over the aged-Cu/CZL under the simulated exhaust condition, significantly outperforming the conventional counterpart, PtPd/γ-Al2O3.

Sol-gel synthesized rare earth La3+ ions doped Zn2SiO4 phosphors for lighting applications

In this study, Zn2-xLaxSiO4 (x = 0.00, 0.02, 0.04, and 0.06) materials with varying weight percentages of lanthanum (La) in zinc silicate (Zn2SiO4) were synthesized using the sol-gel process. The effect of La dopant on the structure, morphology, and optical characteristics of Zn2SiO4 was investigated through various analytical and spectroscopical techniques. According to PXRD measurements, La3+ ions were incorporated into the host materials of Zn2SiO4, considerably affecting their crystallinity. Irregular granular and pebble stone-like morphology was observed in the FESEM analysis. The optical energy bandgap of La-doped Zn2SiO4 materials decreased from 5.09 eV to 3.80 eV while increasing the La dopant into Zn2SiO4 host systems. The photoluminescence (PL) spectra and photoluminescence quantum yield (PLQY) confirmed the increase of luminescent peak intensity at 730 nm. A tri-exponential fitting technique was used to determine the luminescence decay lifetime of the significant emissions of La-doped Zn2SiO4, and the average lifetime was found to be 30.4 ns. Dosimetry could benefit significantly from the thermoluminescence investigation conducted for the La-doped Zn2SiO4 phosphor at a linear heating rate of 8 °C/s.

Enhancing CO2 photoconversion activity of TiO2 via synergistic effects of La-doping and ammonia vapor heat treatment

A novel, sample and economical method was used to prepare the new co-doped TiO2 photocatalysts and evaluated for CO2 photoconversion under visible-light irradiation. The La(NO3)3-TiO2 photocatalyst was obtained by the sol–gel method and then was heat treated with different concentrations of ammonia vapor. It was found that the synergistic modification of TiO2 photocatalyst by La(NO3)3 and ammonia vapor could improve its photocatalytic performance under visible light. The photocatalytic assessment presented a significantly amelioration in CO2 photoconversion, giving 3.078 μmol CH4 production in 4 h. The structures and properties of the photocatalysts were characterized and analyzed by means of XRD, SEM-EDS, HRTEM, BET, XPS, FTIR, ICP-AES, UV–vis DRS and theoretical calculation. The performance of the photocatalyst could be correlated to contributions of various phenomena such as larger specific surface area and the co-exposed (101) and (001) facets of anatase TiO2. Finally, the most likely substituted structures were obtained. The results of DFT + U theoretical calculation showed that La and N could modify TiO2 by replacing surface Ti atoms and internal O atoms, respectively.

Structure and electrical properties of La2O3-doped (K,Na,Li)(Nb,Ta)O3-(Bi,Na)TiO3 ceramics

In this paper, Lead-free based on 0.97([Formula: see text][Formula: see text][Formula: see text])([Formula: see text][Formula: see text])O3–0.03[Formula: see text][Formula: see text]TiO3 with additives La2O3 (1, 2, 3, 4 wt.%) was prepared by the solid reaction method, and the effect of La dopant on the structural and electrical properties is investigated. The result indicates La dopant considerably decreases the optical band gap compared to the undoped composition. On the other hand, La doping leads to the higher dielectric property in a wider temperature, providing possibilities and directions for the subsequent development of ferroelectric photovoltaic materials with electrical properties and low optical band gap in a dramatical manner.

Effect of La substitution on the structural and chemical properties of Barium hexaferrite via Mossbauer spectroscopy

M-type Barium hexaferrite is a famous hard magnetic material with a hexagonal crystal structure. La substituted Barium hexaferrite, Ba(1-x)La(x)Fe12O19, (where, x = 0.25 and 0.30) were synthesized using ball milling followed by sintering at 1300 °C for 5 hours. X-ray diffraction patterns reveal the formation of a single-phase magnetoplumbite structure of barium hexaferrite, which belongs to the P63/mmc space group. Mossbauer spectroscopic studies were carried out to study the magnetic phase, the effect of La doping on the valency of the Fe atom, and charge distribution in the prepared samples. Mossbauer spectra is fitted using 5 sextets, shows there is 5 sublattices present in the system. From the fitting of Mossbauer spectrum, it is observed that, there is no formation of Fe2+ ion even if the doping levels are as high as 30%, as it is expected that Fe3+ ion changes its valance to maintain the charge neutrality. However, there is an increase in s-electron density for number of sites with doping. Quadrupole splitting values shows spherical charge distribution for all the sublattices except 2b, due to asymmetric nature of bipyramidal site. Slightly varied magnetic hyperfine splitting values are observed for 12 k and 4f1 sites shows the effect of La substitution.

La-doped NiWO4 coupled with reduced graphene oxide for effective electrochemical determination of diphenylamine.

Diphenylamine (DPA) is a harmful pesticide widely used to control post-harvest scald of fruits. In this study, rapid and sensitive determination of DPA was realized by the development of an effective electrochemical sensor, which was fabricated by coupling La-doped NiWO4 nanoparticles (La/NiWO4) with reduced graphene oxide (rGO), and the obtained rGO/La/NiWO4 nanocomposite was modified on glassy carbon electrodes (GCEs). The morphologies, structures and compositions were well characterized, and the effects of La doping and the introduction of rGO on the crystal structure and electrochemical performance were discussed. The incorporation of both La and rGO was found to enhance the active surface area and improve conductivity, resulting in the enhanced electrocatalytic performance of rGO/La/NiWO4/GCE, including a wide linear range (0.01-500 μM), a low detection limit (0.0058 μM) and high sensitivity (1.778 μA μM-1 cm-2). The fabricated sensor was further used for DPA detection in fresh apple extract to evaluate its practicality and demonstrated excellent recoveries ranging from 99.52 to 104.70%.

Effect of La doping on structure and properties of Y2O3/Diamond films

Effect of La doping on structure and properties of Y2O3/Diamond films

Effect of La Doping on the Radiation Damage Effect of Er3+-Doped Silica Fibers for Space Laser Communication

Effect of La Doping on the Radiation Damage Effect of Er3+-Doped Silica Fibers for Space Laser Communication