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101.
Qiuming Wei Wei Li Chun Jin Yasi Chen Linlin Hou Zhiliang Wu Zhongliang Pan Qinyu He Yinzhen Wang Dingyuan Tang 《中国稀土学报(英文版)》2022,40(4):595-604
Photocatalytic technology can solve various environmental pollution problems, especially antibiotic pollution. A novel La-doped MIL-53(Al)/ZnO composite material was successfully synthesized by a combination of hydrothermal method and calcination, showing high photocatalytic degradation percent of sulfamethazine (SMT). The 2 mol% La MIL-53(Al)/ZnO photocatalyst shows the highest degradation efficiency toward SMT (92%) within 120 min, which is 4.1 times higher than pure ZnO (increased from 18% to 92%). In addition, the degradation analysis of SMT by high performance liquid chromatography proves that the products are CO2 and H2O. The improved photocatalytic activity is mostly caused by the following factors. (1) Doping La ions can decrease the band gap of ZnO, enhance light response, and effectively enhance the separation rate of photo-generated holes and electrons. (2) MIL-53(Al) can adsorb SMT and promote the separation of electron. This work shows that the synthesized La-doped MIL-53(Al)/ZnO photocatalyst is expected to be used as a green and effective method for treatment of environment water pollution. 相似文献
102.
ＳｔｕｄｙｏｎＭｏｎｏｘｉｄｅＥｍｉｓｉｏｎＳｐｅｃｔｒｏｍｅｔｒｙｏｆＲａｒｅＥａｒｔｈＥｌｅｍｅｎｔｓⅠ．ＤｅｔｅｒｍｉｎａｔｉｏｎｏｆＳｍｉｎＲａｒｅＥａｒｔｈＣｏｎｃｅｎｔｒａｔｅｂｙＤｕａｌＷａｖｅｌｅｎｇｔｈＭｅｔｈｏｄＺｈａｎｇＺａｉｚ... 相似文献
103.
本文研究了TRPO-煤油对硝酸体系中的锕的萃取,确定了萃取络合物的组成;测定了表观平衡常数;并研究了各种因素对Ac的萃取的影响。在实验基础上推导出了计算Ac的分配比的经验公式。还研究了TRPO-煤油对常量La的萃取,并讨论了使用TRPO萃取实现La,Ac分离的可能性。 相似文献
104.
La2Ce2O7(LC) 和 LaMgAl11O19(LMA) 是两种新型热障涂层材料。 LC 具有优良的热物理及抗腐蚀性能, 但其断裂韧性差。 LMA 具有良好的综合性能, 特别是力学性能优良。 基于复合材料设计理念, 为充分利用 LC 和LMA 的优势, 本文探究了制备 LMA-LC 双相复合陶瓷的可行性。 采用高温固相法合成了 LMA 和 LC 粉末, 重点研究了 LMA 和 LC 的高温稳定性, 初步研究了 LMA-LC 复合陶瓷块材的力学性能。 结果表明： LMA 和 LC 在高温下发生了化学反应, 反应程度随温度升高而加剧, 主要反应产物为 LaAlO3, 其在低温下的铁弹性可能是复合陶瓷在室温下具有良好力学性能的原因。 相似文献
105.
《Ceramics International》2023,49(19):31428-31438
Lanthanum silicate oxyapatite (LSO) is a promising alternative electrolyte for solid oxide fuel cell (SOFC) applications. They exhibit anisotropic oxide-ionic conduction; therefore, a preferential crystal orientation along the c-axis is necessary to achieve optimal conductivity. This study is performed to understand the reaction mechanisms involved in the formation of an LSO layer at the interface of the La2SiO5/SiO2 diffusion pair during reactive sintering at high temperatures. Different La2SiO5/SiO2 bilayers were fabricated in sandwich-type structures using silica-type quartz or La2SiO5 supports obtained via electrophoresis and uniaxial pressing, respectively. These supports were pre-sintered and then coated with a suspension of the opposite component. The diffusion pairs were isothermally heated at 1500 °C at different holding times (10, 20, and 40 h) and at 1600 °C for 10 h. Their surfaces and cross-sections were investigated via X-ray diffraction, scanning electron microscopy (SEM) observations, energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy.Experimental results show that two different driving forces were involved in the nucleation and growth of apatite crystals. The first is the chemical potential gradient in lanthanum between the components of the layers, and the second is the electric field created to preserve the electroneutrality of the system. The predominant diffusing species in this bilayer system were La+III and O-II, and their diffusion is enhanced by the formation of a glassy phase on the silica grains through the transformation of silica-type quartz into cristobalite. The formation of a La2Si2O7 intermediate phase was detected, which is vital to the interdiffusion of species and the nucleation and growth of oriented apatite crystals. The porosity gradient observed in the cross-section after reactive diffusion suggests the possibility of achieving an SOFC half-cell device via this process. 相似文献
106.
《International Journal of Hydrogen Energy》2023,48(35):13109-13122
Photocatalytic selective organic transformations (SOTs) with H2 production in one reaction system represent a route with great promise for green and sustainable organic synthesis and clean fuel generation. In this work, a new La-ion engineering strategy was employed to elaborately fabricate Ni2P/CdLaS (NP/CLS) composite photocatalysts, which significantly improved the visible light-initiated alcohol oxidation-hydrogen production performance. The optimized 1.5% NP/CLS sample showed a maximum production rate of H2 (15.35 mmol·h−1·g−1) and aromatic aldehyde (15.83 mmol·h−1·g−1) under visible light illumination (λ ≥ 420 nm), which are 3.4 times higher than that of Ni2P/CdS (NP/CS) and 20 times higher than that of CLS. The apparent quantum efficiency over 1.5% NP/CLS sample could reach up to 11.22% at 450 nm. The superior performance of the photocatalytic H2 production results over 1.5% NP/CLS sample could be mainly ascribed to the following synergistic effects. Firstly, the formed intimate Ohmic contact between NP and CLS can increase the separation speed of photo-generated charge carriers, meantime, reducing the overpotential for H2 evolution. Secondly, the introduced La ions in NP/CLS effectively strengthen photogenerated electron transfer. The detailed physical and chemical characterization results, in-situ XPS analysis, and density functional theory (DFT) calculations provide effective support for the proposed photocatalytic reaction mechanism. This work shows a strategy with great promise to design noble-metal-free photocatalysts for high H2 production performance. 相似文献
107.
《International Journal of Hydrogen Energy》2023,48(41):15433-15446
In this study, three-dimensional ordered microporous silica supported p-lanthanum ferrite and n-ceria (n-CeO2@p-LaFeO3/3DOM SiO2) was successfully synthesized as a visible light-driven photocatalyst for activating peroxymonosulfate (PMS) to degrade Bisphenol A (BPA). In a wide pH range (2–12), the BPA degradation efficiency maintained at a high level, organic matter and natural inorganic ions had no significant negative impact. When the BPA concentration was as low as 2 mg·L−1, the removal rate in 60 min still reached 95.56%, indicating that the novel photocatalyst has potential application in the treatment of trace pollutants. The pore confinement effects of catalysts and the synergistic effect between LaFeO3 and CeO2 result in the excellent photocatalytic performance. We proposed the possible mechanism of BPA degradation, specifically involving the recognition and generation mechanism of reactive oxygen species (ROSs), adsorption processes and diffusion processes. In summary, the novel n-CeO2@p-LaFeO3/3DOM SiO2 would be a promising candidate photocatalytic material for practical sewage treatment. 相似文献
108.
《International Journal of Hydrogen Energy》2023,48(47):17838-17851
Sustainable energy innovation is spearheading the way to achieve decarbonisation through commercially viable and highly competitive renewable technologies for green hydrogen. Photocatalytic water splitting has received global attention, as it promotes the direct conversion of solar energy to chemical energy and hydrogen production. Lanthanum orthoferrite (LaFeO3) has been selected due to its narrow bandgap perovskite-oxides (ABO3) type nature, low cost and high chemical stability but it is limited with fast charge recombination. To circumvent its constraint of fast charge recombination, an efficient graphene-based nanocomposite has been prepared by employing reduced graphene oxide (RGO) nanosheets as charge separators for visible light driven photocatalytic water splitting. Here, we present a thorough physical and spectroscopic characterization of the Lanthanum orthoferrite/Reduced Graphene oxide (LaFeO3/RGO) nanocomposites, and investigate its photocatalytic and photoelectrochemical performance. The photocurrent density of the nanocomposites demonstrated ∼21 times higher in comparison to pure LaFeO3. The as-prepared nanocomposites have been successfully used as photocatalysts for H2 generation through water reduction under visible light. A significant enhancement in H2 generation has been recorded for nanocomposites (∼82 mmol g−1 h−1) as compared to that of bare LaFeO3 (∼9 mmol g−1 h−1) which is among the highest values obtained using noble-metal-free graphene-based photocatalytic nanocomposites. This work offers a facile approach for fabricating highly efficient 1D-2D heterostructure for photocatalysis application. 相似文献
109.
《Advanced Powder Technology》2022,33(12):103879
Heat transfer within ceramic feedstock powders is still unclear, which impedes optimization of the thermal and mechanical properties of the thermal sprayed coatings. The microspheres (yttria-stabilized zirconia YSZ and lanthanum zirconate LZO) were prepared via the electro-spraying assisted phase inversion method (ESP). The thermal properties of the two ESP microspheres and a commercial hollow spherical powder (HOSP) were investigated by using theoretical, experimental, and simulation methods. Thermal conductivity of the single microsphere was estimated via a novel nest model that was derived from the Maxwell-Eucken 1 and the EMT model. Thermal conductivity of a single YSZ/LZO-ESP microsphere prepared at 1100–1200 °C was within 0.36–0.75 W/m K, which was ～ 20 % lower than that of a single YSZ-HOSP microsphere with a similar porosity. Heat flux simulation showed that high tortuosity around the multi-scaled voids of the ESP microsphere led to a more efficient decrease in thermal conductivity compared with total porosity. 相似文献
110.
Yong Cao Nanqi Duan Li Jian Anna Evans Reidar Haugsrud 《Journal of the American Ceramic Society》2016,99(10):3309-3316
Hydration properties and electrical characteristics of the high‐temperature proton conductor La27(W0.85Nb0.15)5O55.5?δ are investigated by means of thermogravimetry, impedance spectroscopy, and the electromotive force (EMF) method as a function of temperature, water vapor, and oxygen partial pressures, as well as isotope exchange measurements in order to elucidate the mechanism and thermodynamics of protons formation and transport. The highest proton conductivity, 1.3 × 10‐3 S/cm, is achieved at 700°C in wet O2. Proton self‐diffusion coefficients are estimated from thermogravimetric measurements of hydration and conductivity data. Comparison of the conductivity characteristics between nominally pure and Nb‐substituted materials reveals that the ionic conductivity increases and the activation energy decreases with Nb doping. These differences are discussed to reflect changes in the structure promoting ionic transport rather than changing the concentration of defects to any large extent. 相似文献