La2O3 Nanoparticles Research Articles

A Facile Synthesis of La2O3/GO Nanocomposites in N,N-Dimethylformamide with High Dye Degradation Efficiency

La2O3/graphene oxide (GO) nanocomposites were simply synthesized from commercially available LaCl3·7H2O and multilayer GO (5–10 layers) in N,N-dimethylformamide (DMF) under reflux condition without extra stabilizer. The characterization results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) spectroscopies showed that the crystalline La2O3 nanoparticles were successfully attached on the surface of GO. Moreover, the as-prepared nanocomposites greatly enhanced the degradation efficiency of organic dyes after 15 min under ultrasound irradiation in pure water. The degradation efficiency of the nanocomposites for methylene blue could be over 99%.

Combustion combined with ball milling to produce nanoscale La2O3 coated on LiMn2O4 for optimized Li-ion storage performance at high temperature

In this study, La2O3 is synthesized by combustion method and then subjected to ultrafine ball milling to obtain La2O3 nanoparticles. In neopentyl glycol, La2O3 nanoparticles are coated on the surface of spinel LiMn2O4 ultimately obtaining La2O3 coating contents of 1.5, 3, 4.5, and 6 wt%. XRD characterization reveals that the nano La2O3 exhibits a favorable crystalline intensity, without impurities and the crystalline peak of La2O3 can be observed when the coating content is of up to 6 wt%. Successful deposition of a thin layer of La2O3 on the LiMn2O4 surface is confirmed by scanning electron microscopy, transmission electron microscopy, X-ray spectrum elemental plane scanning, and line scanning. Furthermore, inductively coupled plasma emission spectrography and electrochemical impedance spectroscopy analyses show that the nano-La2O3 coating significantly relieves the dissolution of Mn in LiMn2O4 materials, and also improves the electro-conductivity. The electrochemical performances of the coated LiMn2O4 samples are also investigated in this work. Compared with the pristine LiMn2O4, the LiMn2O4 coated with 3 wt% La2O3 exhibits a higher rate capability and better reversibility, exhibiting 103.5 and 90.6 mAh g−1 at 5 and 10 °C, respectively. After 100 cycles at 60 and 1 °C, the 3 wt% nano-La2O3-coated sample still exhibits a high-capacity retention of 91.68%.

Environment effect of La2O3 nano-additives on microalgae-biodiesel fueled CRDI engine with conventional diesel

ABSTRACTIn this present work, corn oil biodiesel with La2O3 was used as an additive with neat diesel fuel and blends were prepared. La2O3 nanoparticles are dispersed in the emulsions with different dosage levels of 50, 75, and 100 ppm. A single-cylinder, four-stroke CRDI diesel engine is made to run on different fuel concentrations to study the effect of emission characteristics of the fuel. The test engine was operated under constant engine speed (1500 rpm) and different engine load test conditions. According to the experimental results, fuel blends with biodiesel fuel emission increases CO2 and NOx and reduces the CO, HC, and smoke emissions compared with the B20 fuel.

Photo-degradation of basic green 1 and basic red 46 dyes in their binary solution by La2O3-Al2O3nanocomposite using first-order derivative spectra and experimental design methodology

In this work, the lanthanum oxide-aluminum oxide (La2O3-Al2O3) nanocomposite is introduced as an efficient photocatalyst for the photo-degradation of the dyes basic green 1 (BG1) and basic red 46 (BR46) in their binary aqueous solution under the UV light irradiation. The properties of this catalyst are determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and UV–visible spectrophotometry. The first-order derivative spectra are used for the simultaneous analysis of the dyes in their binary solution. The screening investigations indicate that five parameters including the catalyst dosage, concentration of the dyes, irradiation time, and solution pH have significant effects on the photo-degradation of the dyes. The effects of these variables together with their interactions in the photo-degradation of the dyes are studied using the Box-Behnken design (BBD). Under the optimum experimental conditions, obtained via the desirability function, the photo-catalytic activities of La2O3-Al2O3 and pure Al2O3 are also investigated. The results obtained show an enhancement in the photo-catalytic activity when La2O3 nanoparticles are loaded on the surface of Al2O3 nanoparticles.

Self-assembled (3-mercaptopropyl)trimethoxylsilane film modified with La2O3 nanoparticles for brass corrosion protection in NaCl solution

Self-assembled monolayers (SAMs) of 3-mercaptopropyltrimethoxysilane (PropS-SH) modified with La2O3 nanoparticles were investigated to evaluate the doping effect of La2O3 nanoparticles on PropS-SH silane film towards brass corrosion protection in NaCl solution. The results indicated that SAMs of PropS-SH modified with La2O3 nanoparticles presented improved barrier properties because La2O3 nanoparticles filled the holes of silane film, which in turn improved the density of silane film, thus enhanced the barrier properties of silane-metal interface. Further, part of La2O3 nanoparticles was transformed to lanthanum oxide hydroxide (LaOOH) by hydrolysis reaction, and the formed La compounds covered the cathode sites, giving rise to a blocking effect.

Practical limitations of single particle ICP-MS in the determination of nanoparticle size distributions and dissolution: case of rare earth oxides

The applicability of single particle ICP-MS (SP-ICP-MS) for the analysis of nanoparticle size distributions and the determination of particle numbers was evaluated using the rare earth oxide, La2O3, as a model particle. The composition of the storage containers, as well as the ICP-MS sample introduction system were found to significantly impact SP-ICP-MS analysis. While La2O3 nanoparticles (La2O3 NP) did not appear to interact strongly with sample containers, adsorptive losses of La3+(over 24h) were substantial (>72%) for fluorinated ethylene propylene bottles as opposed to polypropylene (<10%). Furthermore, each part of the sample introduction system (nebulizers made of perfluoroalkoxy alkane (PFA) or glass, PFA capillary tubing, and polyvinyl chloride (PVC) peristaltic pump tubing) contributed to La3+ adsorptive losses. On the other hand, the presence of natural organic matter in the nanoparticle suspensions led to a decreased adsorptive loss in both the sample containers and the introduction system, suggesting that SP-ICP-MS may nonetheless be appropriate for NP analysis in environmental matrices. Coupling of an ion-exchange resin to the SP-ICP-MS led to more accurate determinations of the La2O3 NP size distributions.

Preparation, Characterization and Electrochemical Study of Lanthanum-Silica Sol-Gel Thin Films

This work presents a low cost environmentally friendly alternative to corrosion protection of aluminium alloy based on silica sol-gel thin films doped with lanthanum compounds. Sols were prepared from solutions composed of tetraethylorthosilicate and methyl-triethoxysilane as precursors, distilled water to perform the hydrolysis, absolute ethanol as solvent and nitric acid as catalyst. Lanthanum acetate hydrate or lanthanum isopropoxide in three different concentrations were added as doping agents. These lanthanum compounds can play as the well-known Cr (VI) salts offering a suitable protective effect without any environmental negative impact. L-cysteine as green corrosion inhibitor has been also added to a set of sol formulations. Films were deposited upon microscope glass slides and aluminium alloy AA2024-T3 sheets by dip coating at a constant drawing speed (2.0 mm·s−1), in a controlled room under 25°C and 35% relative humidity. For convenience, sol-gel monoliths of 20 mm diameter were also prepared. After coating, monoliths and films were dried and annealed in air at 20, 100 and 500 °C. A model polyvinyl butyral film was applied on a series of these sol-gel coatings to simulate the performance of commercial anticorrosive paints (organic coatings). For this matter poly (vinyl butyral-covinyl alcohol-co-vinyl acetate) solutions (17% w/w) were prepared in ethanol. Transmission spectra of the as prepared films were recorded with a UV–VIS-NIR double-beam spectrophotometer equipped with an integrating sphere. Optical measurements (from UV-Vis absorption and diffuse reflectance spectroscopies) pointed out that the coatings were colourless and transparent, and they diminish the diffuse reflectance of the metallic surface up to ∼60 %. Scanning electronic microscopy coupled with energy dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM) and contact angle measurements were also applied for the coatings characterization. As concerns the structural characterization of the lanthanum environment X-ray Absorption Fine Structure (XANES) and X-ray Absorption Near Edge Structure spectroscopy (EXAFS) were also performed. Likewise, the remaining sols were kept to gelify at 60 °C for 4 days and then powdered to obtain suitable samples to be analysed by using other characterisation techniques (Fourier transformed infrared, FTIR, and differential thermal analysis, DTA). The corrosion resistance of the sol-gel coated AA2024-T3 aluminium alloy was studied by weathering tests according to modified ISO 1776 and 695 Standards. Samples were immersed into an acid solution (HCl 0.1 N at 25 °C) or into a basic one (NaOH 0.1 N at 25°C) for 1 h. In parallel studies, anodic and cathodic delamination tests were also carried out during immersion of coated samples into a 0.6 M NaCl aqueous solution. Just before the experiment was initiated, the centre of the PVB/sol-gel thin film/metal samples was damaged with an intentionally scribed linear defect. Potentiodynamic polarization technique and global and electrochemical impedance spectroscopy were also applied. The results show that the presence of lanthanum compounds and L-cystiene induces an effective delay of early corrosion of metallic substrates, demonstrated by accelerated corrosion tests in acid and basic media. XAS studies confirmed the incorporation of lanthanum ions into silica sites to be essential for the material anticorrosive properties. Optical and scanning electron microscopies allowed the coated samples texture and microstructure observation, both before and after the corrosion tests were carried out. These last two techniques joined with the electrochemical studies allowed to evaluate not only the inhibitor effect of lanthanum compounds and L-cysteine, but also the self-healing properties of the studied systems. As concluding remarks, we may indicate the convenience and effectiveness of the prepared sol-gel silica films doped with lanthanum isopropoxide or lanthanum acetate as a protective barrier for the delay of early corrosion of metallic surfaces. These properties are scarcely dependent on the lanthanum precursor used, which could be selected taking in mind the corresponding cost. Depending on the reaction parameters in the sol-gel process, La2O3 or La(OH)3 nanoparticles can be intentionally produced. The combination of these La2O3 nanoparticles with L-cysteine produces a synergic effect which improves considerably the corrosion protection behaviour of sol-gel coated AA2024-T3 aluminium alloy in NaCl aqueous solutions. The uniformly distributed La2O3 or La(OH)3 nanoparticles impregnated with corrosion inhibitor behave as active fillers and nanoreservoirs for the sol-gel thin film, providing a prolonged and smart release of the corrosion inhibitor (L-cysteine) in response to local pH changes during the samples contact with the aqueous solutions. The action of the organic inhibitor combined with the precipitation of insoluble lanthanum products from the inorganic framework at the cathodic and anodic corrosion zones, provides self-healing properties to the protective system, avoiding the corrosion processes as expected. Acknowledges: This work was supported by MINECO, Spain (Projects MAT2012-38541-C02-02, MAT2015-65445-C2-1-R and MAT2015-65445-C2-2-R).

Hybrid Energy Harvester Using Piezoelectric and Pyroelectric Properties of PVDF Nanocomposite Films

This paper reports a novel hybrid piezoelectric-pyroelectric energy harvester using a copper cantilever beam with PVDF thick films. Polyvinylidene fluoride (PVDF) is used as the piezoelectric material, which also has pyroelectric characteristics. We will present an experimental study of electrical output parameters and the resonance frequencies of different thick piezoelectric films attached at the clamped end of copper beam. The experiments were carried out with different plate piezoelectric films such as; polyvinylidene fluoride (PVDF), PVDF/PZT, and PVDF/PZT with multi walled carbon nanotubes (MWCNT) with the thickness of 0.2 mm. The output power was measured with changing the load resistance and the optimum value was found around 1 MΩ. The maximum output power obtained at resonance frequency of the optimum resistance was 0.39, 0.84, and 1.3 nW for PVDF, PVDF/PZT, and PVDF/PZT MWCNT, respectively. By heating the film as well with infrared lamp, the output voltage shall be enhanced. The results of La2O3 nanoparticles embedded in PVDF matrix will also be presented

Optical and electronic characterization of P(VDF-TrFE)/La2O3 nanocomposite films

In this study, the pristine and La2O3-embedded poly vinylidene fluoride/trifluoroethylene [P(VDF-TrFE)] thick films were fabricated via solution casting technique and optical and dielectric properties investigated. P(VDF-TrFE)] is a potential candidate for electromechanical and acoustic sensors, actuators, energy harvesting and nonvolatile memory applications. Infrared vibrational spectroscopy (Raman) revealed enhancement of β-phase in the composite films. At room temperature, in the ultraviolet-visible range both the absorption and the optical bandgap (Eg) increased in nanocomposite films. Dielectric properties for nanocomposite films have been measured as a function of frequency in the range of 1kHz to 1MHz and temperature in the range from 20°C to 80°C. The dielectric results show increase in real and imaginary part of dielectric constant with temperature and volume fraction of La2O3 nanoparticles dispersed. The ac and dc activation energies were found to decrease with increase in volume fraction of nanoparticles following Arrhenius relationship. Thus, showing the conduction was thermally activated.

Effect of La2O3 Nanoparticles on the Brazeability, Microstructure, and Mechanical Properties of Al-11Si-20Cu Alloy

The Al-11Si-20Cu brazing alloy and its ex situ composite with the content ranging from 0.01 to 0.05 wt.% of La2O3 are produced by electromagnetic induction-cum-casting route. The brazeability of the alloy and composite samples are tested using the spreading technique according to JIS Z-3197 standard. The mechanical properties such as filler microhardness, tensile shear strength, and elongation of the brazed joints are evaluated in the as-brazed condition. It is reported that incorporation of an optimal amount of 0.05 wt.% of hard La2O3 nanoparticles in the Al-Si-Cu matrix inhibits the growth of the large CuAl2 intermetallic compounds (IMCs) and Si particles. As a consequence, the composite filler brazeability, microhardness, joint tensile shear strength, and elongation are improved significantly compared to those of monolithic Al-11Si-20Cu alloy.

MnO2 Nanotube-Supported CaO Nanoparticle, La2O3 Nanorod and Its Cabon Nanotube Hybridmaterial (La2O3/CaO/MnO2-CNTs) As Bi-Functional Cathode Catalysts for Rechargeable Zinc-Air Batteries

The whole world has been in transition from a fossil fuel based economy to a clean energy economy. Especially in today's society, the demand for energy is increasing, the fossil fuel is exhausted and the environmental safety is becoming more and more important. [1-3]This inevitable process is being accelerated by recent active research on sustainable energy scavenging, conversion and storage. Batteries have long been accepted for their capacity to efficiently convert and store electrical energy[ 4] . To the best of our knowledge, there has been no report on the combination among La2O3, MnO2, CaO and carbon-based materials to form hybrid catalysts for improving the electro-catalytic performance of the materials in rechargeable metal-air batteries. It is expected that by combining the transition metal oxides with carbon-based material via a facile hydrothermal process would lead to a strong hybrid effect to enhance the catalytic performance. Based on this strategy, we have designed and synthesized the hybrid material via a facial method where the precursors of the metal-oxide (La, Mn and Co) and CNTs are justly mixed into a single reaction to produce the final catalysts. First, MnO2 nanotubes were prepared by a facile hydrothermal method. Then CaO nanoparticles and La2O3 nanoparticles were modified on the MnO2 nanotubes by a hydrothermal method combined with post-heat treatment. In a typical synthesis of La2O3/CaO/MnO2-CNTs hybrid nanomaterials, 0.25 g Ca(NO3)2▪4H2O and 0.25g La(NO3)2▪6H2O were dissolved in 15 mL of 1.3 mol L-1 ammonia solution. Afterwards, 0.125 g as-prepared MnO2 nanotubes and 0.125g CNTs were dispersed in the above solution by hydrothermal for 60 min. The resulting products. were separated by centrifugation, washed with deionized water, dried at 60 ℃ for 5 h, and then calcined in air at 400℃ for 1 h. As shown in Fig.1, the onset potential for was detected at 0.94 V for (MnO2/Co3O4)/CNTs,whereas it was 1.08 V and 0.78 V for Pt/C and CNTs, respectively. At 0.2 V, La2O3/CaO/MnO2-CNTs, Pt/C and CNTs afforded an ORR current density of 5.2mA cm-2 ,3.6mA cm-2and 2.2mA cm-2 .Apart from the ORR activity, excellent OER activity is particularly critical for bi-functional catalysts. As shown , the onset potential for was detected at 1.46V for La2O3/CaO/MnO2-CNTs, whereas it was 1.59V and 1.60V for CNTs and 20%Pt/C,the OER current density of La2O3/CaO/MnO2-CNTs,20%Pt/C and CNT at 1.67 V was 8 and 0.7 and 0.3mA cm- 2.A rotating disc electrode (RDE) half-cell setup was used to investigate the ORR and OER catalytic activity of the samples. The working electrode was fabricated by casting Nafion-impregnated catalyst ink onto a glassy carbon disk electrode (5.6 mm in diameter). 10 mg of the catalyst was ultrasonically dispersed into 1mL ethanol 8 and uL 5 wt% Nafion solution to form a catalyst ink. 5uL of the catalyst ink was deposited on the disk and dried at room temperature. The working electrode was allowed to achieve a catalyst loading of 0.1 mg cm-2. Electrochemical activity of the samples was studied using linear sweep voltammetry. The working electrode was immersed in a glass cell containing 0.1 M KOH aqueous electrolyte. A platinum foil and an Hg/HgO electrode were used as the counter and reference electrodes, respectively. Catalyst activity toward the ORR and OER was evaluated in oxygen-saturated electrolyte solution from 1.67 to 0.1 V vs. RHE. The potential of the reference electrode was normalized with respect to the potential of the reversible hydrogen electrode (RHE). The rotation rate is 1600 rpm and the scan rate is 5 mV s-1. A commercial Pt/C catalyst (30 wt% platinum on carbon) was tested using the same procedure. The battery had an open circuit voltage of 1.35 V. At a voltage of 600 mV, it showed a high current density of 375mA cm-2. The peak power density was 258mW cm-2. the battery discharge and discharge performance noticeably at lower current densities and through long cycle times. In summary, La2O3/CaO/MnO2-CNTs a new air electrode material have been synthesized via a two-step hydrothermal method. These hybrid nanomaterials display good bifunctional ORR/OER activity and cyclic stability in the discharge and charge process. Further studies are ongoing to improve the ZABs performance by manipulating the hybrid structure. References 1 M.Armand, J. M.Tarascon, Nature, 451, 652(2008). 2 A. S.Arico, P.Bruce, B.Scrosati, J. M.Tarascon, W. Van Schalkwijk, Nat. Mater., 4, 366(2005). 3 G.Girishkumar, B.McCloskey, A. C.Luntz, S.Swanson, W.Wilcke, J. Phys. Chem. Lett., 1, 2193(2010). 4 R.Cao, J.Lee, M. Liu, J.Cho, Adv. Energy Mater., 2, 816(2012) Figure 1

Perovskite LaNiO3 Nanocrystals inside SBA‐15 Silica: High Stability and Anti‐Coking Performance in the Pre‐Reforming of Liquefied Petroleum Gas at a Low Steam‐to‐Carbon Molar Ratio

AbstractA high loading of LaNiO3 perovskite nanocrystals (83 wt %) was successfully incorporated inside the ordered mesoporous framework of SBA‐15 silica by a citric acid assisted impregnation method. The obtained LaNiO3/SBA‐15 material produced both La2O3 nanoparticles and metal Ni nanoparticles with intimate contact and highly dispersed in the mesoporous SBA‐15 framework upon reduction with H2, and it showed high activity, high stability, and good anti‐coking ability for the low‐temperature steam reforming of liquefied petroleum gas at a low steam/carbon ratio of 1.0. The excellent performance of the LaNiO3/SBA‐15 material was attributed to the formation of synergistic active sites in the interfacial area, which consisted of metal Ni and La2O2CO3 species, and the confinement effect of the mesoporous structure on the Ni and La2O3 species.

Toxicological Assessment of CoO and La2O3 Metal Oxide Nanoparticles in Human Small Airway Epithelial Cells.

Cobalt monoxide (CoO) and lanthanum oxide (La2O3) nanoparticles are 2 metal oxide nanoparticles with different redox potentials according to their semiconductor properties. By utilizing these two nanoparticles, this study sought to determine how metal oxide nanoparticle's mode of toxicological action is related to their physio-chemical properties in human small airway epithelial cells (SAEC). We investigated cellular toxicity, production of superoxide radicals and alterations in gene expression related to oxidative stress, and cellular death at 6 and 24 h following exposure to CoO and La2O3(administered doses: 0, 5, 25, and 50 µg/ml) nanoparticles. CoO nanoparticles induced gene expression related to oxidative stress at 6 h. After characterizing the nanoparticles, transmission electron microscope analysis showed SAEC engulfed CoO and La2O3nanoparticles. CoO nanoparticles were toxic after 6 and 24 h of exposure to 25.0 and 50.0 µg/ml administered doses, whereas, La2O3nanoparticles were toxic only after 24 h using the same administered doses. Based upon the Volumetric Centrifugation Methodin vivoSedimentation, Diffusion, and Dosimetry, the dose of CoO and La2O3nanoparticles delivered at 6 and 24 h were determined to be: CoO: 1.25, 6.25, and 12.5 µg/ml; La2O3: 5, 25, and 50 µg/ml and CoO: 4, 20, and 40 µg/ml; and La2O3: 5, 25, 50 µg/ml, respectively. CoO nanoparticles produced more superoxide radicals and caused greater stimulation of total tyrosine and threonine phosphorylation at both 6 and 24 h when compared with La2O3nanoparticles. Taken together, these data provide evidence that different toxicological modes of action were involved in CoO and La2O3metal oxide nanoparticle-induced cellular toxicity.

Differential pulmonary effects of CoO and La2O3 metal oxide nanoparticle responses during aerosolized inhalation in mice.

BackgroundAlthough classified as metal oxides, cobalt monoxide (CoO) and lanthanum oxide (La2O3) nanoparticles, as representative transition and rare earth oxides, exhibit distinct material properties that may result in different hazardous potential in the lung. The current study was undertaken to compare the pulmonary effects of aerosolized whole body inhalation of these nanoparticles in mice.ResultsMice were exposed to filtered air (control) and 10 or 30 mg/m3 of each particle type for 4 days and then examined at 1 h, 1, 7 and 56 days post-exposure. The whole lung burden 1 h after the 4 day inhalation of CoO nanoparticles was 25 % of that for La2O3 nanoparticles. At 56 days post exposure, < 1 % of CoO nanoparticles remained in the lungs; however, 22–50 % of the La2O3 nanoparticles lung burden 1 h post exposure was retained at 56 days post exposure for low and high exposures. Significant accumulation of La2O3 nanoparticles in the tracheobronchial lymph nodes was noted at 56 days post exposure. When exposed to phagolysosomal simulated fluid, La nanoparticles formed urchin-shaped LaPO4 structures, suggesting that retention of this rare earth oxide nanoparticle may be due to complexation of cellular phosphates within lysosomes. CoO nanoparticles caused greater lactate dehydrogenase release in the bronchoalveolar fluid (BALF) compared to La2O3 nanoparticles at 1 day post exposure, while BAL cell differentials indicate that La2O3 nanoparticles generated more inflammatory cell infiltration at all doses and exposure points. Histopathological analysis showed acute inflammatory changes at 1 day after inhalation of either CoO or La2O3 nanoparticles. Only the 30 mg/m3 La2O3 nanoparticles exposure caused chronic inflammatory changes and minimal fibrosis at day 56 post exposure. This is in agreement with activation of the NRLP3 inflammasome after in vitro exposure of differentiated THP-1 macrophages to La2O3 but not after CoO nanoparticles exposure.ConclusionTaken together, the inhalation studies confirmed the trend of our previous sub-acute aspiration study, which reported that CoO nanoparticles induced more acute pulmonary toxicity, while La2O3 nanoparticles caused chronic inflammatory changes and minimal fibrosis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-016-0155-3) contains supplementary material, which is available to authorized users.

La2O2CO3 Encapsulated La2O3 Nanoparticles Supported on Carbon as Superior Electrocatalysts for Oxygen Reduction Reaction.

Constructing nanoscale hybrid materials with unique interfacial structures by using various metal oxides and carbon supports as building blocks are of great importance to develop highly active, economical hybrid catalysts for oxygen reduction reaction (ORR). In this work, La2O2CO3 encapsulated La2O3 nanoparticles on a carbon black (La2O2CO3@La2O3/C) were fabricated via chemical precipitation in an aqueous solution containing different concentrations of cetyltrimethyl ammonium bromide (CTAB), followed by calcination at 750 °C. At a given CTAB concentration 24.8 mmol/L, the obtained lanthanum compound nanoparticles reach the smallest particle size (7.1 nm) and are well-dispersed on the carbon surface. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results demonstrate the formation of La2O2CO3 located on the surface of La2O3 nanoparticles in the hybrid. The synthesized La2O2CO3@La2O3/C hybrid exhibits a significantly enhanced electrocatalytic activity in electrocatalysis experiments relative to pure La2O3, La2O2CO3, and carbon in an alkaline environment, by using the R(R)DE technique. Moreover, its long-term stability also outperforms that obtained by commercial Pt/C catalysts (E-TEK). The exact origin of the fast ORR kinetics is mainly ascribed to the La2O2CO3 layer sandwiched at the interface of carbon and La2O3, which contributes favorable surface-adsorbed hydroxide (-OH(-)(ad)) substitution and promotes active oxygen adsorption at the interfaces. The unique covalent -C-O-C(═O)-O-La-O- bonds, formed at the interfaces between La2O2CO3 and carbon, can act as active sites for the improved ORR kinetics over this hybrid catalyst. Therefore, the fabrication of lanthanum compound-based hybrid material with an unique interfacial structure maybe open a new way to develop carbon-supported metal oxides as next-generation of ORR catalysts.

Micelle assisted synthesis of La2O3 nanoparticles and their applications in photodegradation of bromophenol blue

Lanthanum Oxide (La2O3) nanoparticles were synthesized by precipitation method using alkylbenzyl dimethyl ammonium chloride (Benzalkonium chloride) surfactant. The critical micelle concentration (CMC) value of the surfactant was determined using conductance and surface tension methods. The nanoparticles were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis. Crystallite size and geometry of La2O3 nanoparticles, established through XRD, are 40 nm and hexagonal, respectively. The optical property was calculated using solid phase UV-visible absorption spectrophotometer with band gap of 4.2 eV. Photocatalytic efficiency of La2O3 nanoparticles was studied against bromophenolblue (organic pollutant) with and without UV radiations. Percentage degradation and first order rate constant values were determined as 24.7% and 0.0942 min–1 without irradiation and that they were 50.4 % and 0.0941 min-1with irradiation, respectively.

Influence of La2O3 nanoparticle additions on microstructure, wetting, and tensile characteristics of Sn–Ag–Cu alloy

In this study, the effect of La2O3 nanoparticles (0, 0.01, 0.03, 0.05 and 0.1 wt.%) has been investigated in Sn–3.0Ag–0.5Cu (SAC-305) alloy. The various soldering properties have been tested, such as wettability, microstructural evolution, intermetallic compound formation, micro-hardness, tensile strength, and fracture analysis of tensile tested samples. La2O3 nanoparticles are added in the Sn–3.0Ag–0.5Cu alloy by mechanical mixing of powders and melting. The structural and morphological features of the samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electron probe micro-analyzer (EPMA). The experimental results indicate that the best combination of microstructural, wetting and tensile properties is obtained at 0.05 wt.% La2O3 in the solder matrix. The sample reinforced with 0.05 wt.% La2O3 i.e., SAC-0.05 La2O3 exhibits ~ 18% increase in microhardness, ~ 26% increase in the ultimate tensile strength (UTS), and ~ 14% elongation due to the adsorption of high surface energy of La2O3 nanoparticles in the matrix.

Wear behaviour of La2O3/Cu composite under extreme electrical contacts and mechanical load

In the present study, wear behaviour of lanthanum oxide strengthened copper alloy (La2O3/Cu) was investigated under extreme conditions of strong currents, heavy loads and high speeds. The results showed that the wear rate of La2O3/Cu was positively correlated with current and inversely related to load. Microstructure and phase composition of wear surface were analysed using optical microscope, scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer. Obvious damage on the wear surface and a micro-sized affected zone on the surface of the matrix was observed, which were attributed to arc erosion wear as well as the interaction effect of the extreme conditions. The affected zone was divided into a deposition layer, softened layer and strengthened layer. La2O3 nanoparticles acting as effective nuclei of heterogeneous nucleation during the crystallisation process impelled the formation of the strengthened layer.

Interfacial compounds growth of SnAgCu(nano La2O3)/Cu solder joints based on experiments and FEM

SnAgCu alloys are promising as the lead-free solders for replacing traditional SnPb solders, 0.1wt.% La2O3 nano-particles are selected as the additives into these solders for further improve the property. The interface reaction and the growth kinetics of intermetallic compounds (IMC) at SnAgCu/Cu and SnAgCu-nano La2O3/Cu interface were investigated during thermal cyclic loading. The growth rate of IMC in SnAgCu-nano La2O3/Cu is lower than that of SnAgCu/Cu, the La2O3 nanoparticles can reduce the diffusion coefficient and activation energies of IMC layers. And the finite element simulation demonstrates that von Mises stress concentrates at the Cu3Sn layer near Cu6Sn5 layer, the crack can be found in the stress concentrated area in the experiment, and SnAgCu-nano La2O3/Cu shows small length of crack comparing with SnAgCu/Cu, which demonstrates the La2O3 nanoparticles can enhance the reliability of SnAgCu/Cu solder joints.

Effects of Electrospinning Parameters and Nanofiller Content on Morphology and Gel Electrolyte Properties of Composite Nanofibers Based on La2O3-Filled PVDF-HFP

This research concerns the development of a composite gel polymer electrolyte based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers. The nanofibers containing La2O3 nanofiller were fabricated via an electrospinning process. The aim of this work was to investigate the effects of elctrospining conditions and nanofiller content on morphology and electrolyte properties of the materials. After adding La2O3 nanoparticles into the polymer solution, percentage crystallinity values of the electrospun composite decreased. The addition of La2O3 also resulted in an increase in ion conductivity values of the composite gel polymer electrolyte. The maximum conductivity value of the electrolyte obtained in this study was 1.43 × 10−3 S/cm.