SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2023
·
IF 4.4
Zhenggang Zou,Tingting Guo,Guoliang Gong,Fulin Lin,Yijian Sun,Jianhui Huang,Jinsheng Liao,Herui Wen
The partially and equivalent substitution of La + Mg → Sr + Al in SrAl 12 O 19 lattice is an effective strategy to provide trivalent sites, reduce the site occupation splitting of Al and stabilize the entire lattice. When excited by 397 nm, the Eu 3+ activated La, Mg:SrAl 12 O 19 (ASL) phosphor shows intense linear emission through the 5 D 0 → 7 F 4 transition at 707 nm when compared with SrAl 12 O 19 :Eu 3+ . Especially, the Eu, Mg co-doped Sr 1-x La x Mg x Al 12-x O 19 with certain amount of x = 1/3 exhibits the significant intense photoluminescence, which was demonstrated through a lattice evolutional model. Eu 2+ in the host with 1/3 ratio of (La, Mg) substitution shows broad blue emission and as short fluorescence lifetime as 248 ns. The temperature-depended fluorescence quenching behavior confirms the essence of strong electric-phonon coupling originated from distorted and polarized crystal field around Eu 2+ /Sr 2+ site. Basing on site regulation of SrAl 12 O 19 matrix, our study provides a reference for exploration on efficient rare earth ions activated luminescent laser or scintillation materials.
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Jiaming Wang,Minxin Shi,Yuanyuan Qin,Yuhua Huang,Xiancai Li,Xiaohua Cao
The enrichment and recovery of low concentration rare earth ions from wastewater resources has become an important research direction to achieve high quality utilization of rare earth resources. In this experiment, graphitic carbon nitride was used as the substrate, which was firstly compounded with Fe 3 O 4 to become magnetic graphitic carbon nitride material by alcohol heat method, and then in situ compounded with ZIF-8 in aqueous phase at room temperature to form the composite g-C 3 N 4 /Fe 3 O 4 @ZIF-8. Finally, the composite was characterized. The adsorption performance of g-C 3 N 4 /Fe 3 O 4 @ZIF-8 and the control g-C 3 N 4 /Fe 3 O 4 and ZIF-8 for La(III) under various conditions was investigated by adsorption experiment. In addition, the types and mechanism of La(III) adsorption were discussed by kinetic, isothermal adsorption line and thermodynamic modeling studies. Finally, the stability performance and reusability of the composite were evaluated by regeneration experiments. The result show that g-C 3 N 4 /Fe 3 O 4 @ZIF-8 has good adsorption performance on lanthanide ions. g-C 3 N 4 /Fe 3 O 4 @ZIF-8 reached adsorption equilibrium at about 20 min. When pH is 6 and the solid–liquid ratio of adsorbent is 0.25 g/L, the adsorption amount was 176.68 mg/g. g-C 3 N 4 /Fe 3 O 4 @ZIF-8 had good selectivity for lanthanum(III), and it retains 81 % of initial adsorption performance after five times of reuse.
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Royal Society Open Science
·
2022
·Vol. 9
·期 9
·
IF 3.653
Haijun Cheng,Chang Yu,Hongyun Wang,Xiongmin Liu,Li Ma,Fang Lai
It has been a challenge to synthesize macrolide musk in excellent yields with high purity. KF-La/γ-Al2O3 catalyst was prepared from a highly basic mesoporous framework using a mild method. The prepared KF-La/γ-Al2O3 catalyst was employed for the synthesis of cyclopentadecanolide from methyl 15-hydroxypentadecanoate. The morphology and structure of prepared catalysts were characterized using XRD, TG-DTG, SEM, EDX, TEM, BET and CO2-TPD. The results revealed that the K3AlF6 and LaOF are produced on the surface of KF-La/γ-Al2O3, and LaO can promote the dispersion of KF on the surface of Al2O3. Catalysts pore size main distribution ranges between 10 and 30 nm, the maximum CO2 desorption temperature is 715°C when the La loading is 25%. Because F− ion has a higher electronegativity than O2− ion, the KF-promoted metal oxide (Al2O3 or/and La2O3) contained more strong basic sites, compared with that of the corresponding metal oxide. The yield of cyclopentadecanolide obtained at 0.5 g KF-25La/γ-Al2O3 catalyst and a reaction temperature of 190°C for 7 h were 58.50%, and the content after reactive distillation is 98.8%. The KF-La/γ-Al2O3 catalyst has a larger pore size and basic strength, which is more conducive to the macrolactonization of long-chain hydroxy ester.
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Frontiers in Chemistry
·
2022
·
IF 5.545
Hao Ruixin,Luo Shanshan,Wang Feiyan,Pan Xinyu,Yao Jing,Wu Jielian,Fang Haihong,Li Wenkui
ZnO quantum dots (QDs) have received much attention as biomarkers and drug delivery systems in cancer treatment, due to their low cost, ease of preparation, and pH-responsive degradation. However, its applications are limited by the low quantum yield and light absorption. In this work, a lanthanum-doped zinc oxide (La-ZnO) QDs-based drug delivery platform was constructed. The results show that 4% La doping is the most beneficial for improving the fluorescent properties of the ZnO QDs. After loading the drug, the cell activity was 15% at ZnO@DOX and 12% at La-ZnO@DOX. According to in vitro and in vivo experiment results, the La-ZnO QDs show enhancement of the antitumor effect. Dual enhancement of fluorescence and anti-tumor effects make La-ZnO QDs promising as a drug delivery system in cancer treatment.
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2022
·Vol. 128
·期 11
·1-10
·
IF 2.983
Cui Yongbao,Yan Tianxiang,Wang Zhaohui,Sun Haochen,Lei Xiuyun,Yan Shiguang,Fang Liang,Liu Laijun
(1 − x )K 0.5 Na 0.5 NbO 3 – x La(Zn 0.5 Zr 0.5 )O 3 [(1 − x )KNN– x LZZ, x = 0.005, 0.010, 0.015, 0.020] ceramics were synthesized to fulfill the application requirement of high-temperature ceramic capacitors. The influence of LZZ content on the phase structure, microstructure morphology, dielectric and conductivity behaviors of this system was conducted. An orthorhombic phase for 0.005 ≤ x ≤ 0.010 and an orthorhombic-tetragonal coexisting phase for 0.015 ≤ x ≤ 0.020 were determined by the X-ray diffraction, Rietveld refinement, and dielectric spectra. The ceramic with x = 0.015 exhibits an ultrahigh and stable permittivity ( ε' ~ 1892, ± 15% variation) and a low dielectric loss (tan δ ≤ 0.05) in a wide temperature region of 82–382 °C owing to the composition heterogeneity-induced shoulder-like peak and diffuse phase transition from tetragonal to cubic. The activation energies from the high-temperature dielectric relaxation and conductivity behaviors initially enhance greatly and then increase slowly, which could be related to the synergy effect of decreased oxygen vacancies and microstructure morphology evolution.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Yu Jiang,Marhoun Ferhat,Wenhao Fan,Shaoping Chen,Yachao Wang,Jie Chen,Rasha Abdullah Ahmed Al-Yusufi,Chaochao Dun
Additional cation doping is one of the potential strategies to enhance the thermoelectric (TE) performance of Mg 3 Sb 2 -based materials with precise regulation of interaction between cations and the host. In this work, using Mg 3 Sb 1.5 Bi 0.5 as an example, we confirmed that co-doping rare-earth elements with Y and La is capable to simultaneously improve its power factor and suppress the thermal conductivity : Y is an effective n -type dopant to regulate the optimal carrier concentration, while La doping can modulate the band structure and increase the effective mass that related to the improved Seebeck coefficient . A promising power factor of 18.3 μW cm -1 K -2 is obtained after co-doping. Meanwhile, the lattice thermal conductivity is dramatically reduced to 0.39 W m -1 K -1 at 750 K thanks to the extra defect scattering introduced by Y and La. As a result, a peak figure of merit ( zT ) of 1.76 and a competitive average zT of 1.1 among 300–750 K are achieved in Mg 3.2 Y 0.04 La 0.01 Sb 1.5 Bi 0.5 . The synergistic effect stemming from dual-cations doping provides profound insights for controllable host-dopant design and modulation toward high-efficient n-type TE materials .
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ADVANCED FUNCTIONAL MATERIALS
·
2023
·Vol. 33
·期 34
·2301815
·
IF 19
Yunpeng Zheng,Hetian Chen,Zhifang Zhou,Yueyang Yang,Mingchu Zou,Wenyu Zhang,Bin Wei,Jinghan Cai,Jin-Le Lan,Di Yi,Ce-Wen Nan,Yuan-Hua Lin
Thermoelectric oxide thin films are promising in chip cooling. The issues on the orientation of thin films are essential as they are related to the structures, morphologies, and thermoelectric properties. In this regard, the orientation modulation is conducted on La-doped SrTiO 3 thin films on (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (LSAT) single crystal substrates. Layer-by-layer growth mode is found in (001)- and (110)- oriented thin films, resulting in few grain boundaries (GBs). In (111)-oriented films, island growth mode leads to columnar grain boundaries that build up potential barriers for electrons to be strongly scattered and filtered, suppressing electron mobility and increasing effective mass. In addition, the GBs serve as oxygen vacancy diffusion paths when annealing, causing increased carrier concentration and lattice contraction. The weighted mobility of 71.9 cm 2 V −1 s −1 and electrical conductivity of ≈600 S cm −1 are realized in the (001)-oriented film at room temperature. Ultimately, outstanding power factor values of ≈569 µW m −1 K −2 (room temperature) and ≈791 µW m −1 K −2 (573 K) are successfully achieved, outperforming those in polycrystalline ceramics and (111)-oriented films. This study systematically investigates the influence of grain boundaries and orientations on SrTiO 3 -based thermoelectric films, which lays a solid foundation for improving thermoelectric performance in other oxide thin films.
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Nature Communications
·
2023
·Vol. 14
·期 1
·1-12
·
IF 16.6
Zhou Min,Wang Zhiqing,Mei Aohan,Yang Zifan,Chen Wen,Ou Siyong,Wang Shengyao,Chen Keqiang,Reiss Peter,Qi Kun,Ma Jingyuan,Liu Yueli
The precise construction of photocatalysts with diatomic sites that simultaneously foster light absorption and catalytic activity is a formidable challenge, as both processes follow distinct pathways. Herein, an electrostatically driven self-assembly approach is used, where phenanthroline is used to synthesize bifunctional LaNi sites within covalent organic framework. The La and Ni site acts as optically and catalytically active center for photocarriers generation and highly selective CO 2 -to-CO reduction, respectively. Theory calculations and in-situ characterization reveal the directional charge transfer between La-Ni double-atomic sites, leading to decreased reaction energy barriers of *COOH intermediate and enhanced CO 2 -to-CO conversion. As a result, without any additional photosensitizers, a 15.2 times enhancement of the CO 2 reduction rate (605.8 μmol·g −1 ·h −1 ) over that of a benchmark covalent organic framework colloid (39.9 μmol·g −1 ·h −1 ) and improved CO selectivity (98.2%) are achieved. This work presents a potential strategy for integrating optically and catalytically active centers to enhance photocatalytic CO 2 reduction.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Xiufan Liu,Yani Luo,Cancan Ling,Yanbiao Shi,Guangming Zhan,Hao Li,Huayu Gu,Kai Wei,Furong Guo,Zhihui Ai,Lizhi Zhang
Herein, we demonstrate that the rare-earth La single catalyst with multi-shell characteristic is an excellent choice for this purpose. By merit of its unsaturated orbitals of La, the single La atom strongly bonds with the two-coordinated lattice oxygen on the oxygen-deficient MoO 3−x to form O 2c -La-O 2c coordination. This robust metal-support interaction frees single atoms from detachment or aggregation, and prevents catalyst from deactivation. Meanwhile, the occupied 5d orbitals of La back-donate electrons to the 2π* molecular orbitals of adsorbed N 2 that substantially activate the inert N N bond towards successive hydrogenation. And single La atom could optimize the electron property of the MoO 3−x support to promote photocatalytic nitrogen fixation. Without any sacrificial agents, this single atom La catalyst with a well-designed coordination structure delivers an impressive NH 3 production rate of 209.0 μmol h 1 g 1 under visible light, outperforming most reported single atom photocatalysts.
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ACS Sustainable Chemistry & Engineering
·
2020
·
IF 7.632
Haowei Li,Xinlai Zheng,Huimin Zhang,Xuehui Li,Jinxing Long
Novel strategies for converting renewable lignin to bulk petrochemicals are highly desirable for achieving sustainable practices in the age of environmental awareness. Herein, we propose an efficient approach for the selective hydrogenolysis of lignin promoted by a cost-effective La3+-doped Ni/MgO catalyst. The results reveal that 84.44% lignin is converted at 270 °C for 4 h, yielding 16.50% volatile products. Importantly, approximately 43.45% of these volatile products are identified as 4-ethyl phenol (7.17% yield), an important intermediate in the fine chemical industry. Intensive analysis of the lignin before and after the reaction confirms that efficient cleavage of the ester linkages is achieved, which correlates directly with the high selectivity of 4-ethyl phenol after a readily decarboxylation reaction. Furthermore, the catalyst characterization demonstrates that La3+ suppresses the formation of a NiMgOx solid solution. Consequently, a greater degree of Ni2+ becomes reducible and the catalyst basicity becomes stronger, both of which are essential for the efficient lignin depolymerization and char reduction. As a result, a significant increase of the yield of volatile products is shown along with a substantial inhibition of biochar formation over the La-doped Ni/MgO catalyst in comparison with that without La doping. Therefore, the present work provides a new insight on producing fine chemicals via a sustainable route.
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Journal of Physical Chemistry C
·
2020
·
IF 4.189
Boyi Wang,Shuqi Zheng,Yuxuan Chen,Yue Wu,Juan Li,Zhen Ji,Yuning Mu,Zhibo Wei,Qian Liang,Jingxuan Liang
How to further improve the thermoelectric performance in Cu3SbSe4-based materials after optimizing its carrier concentration is a difficult issue. The present study attempts to address the issue by investigating thermoelectric performance of Cu3SbSe4 after Sn and La codoping, and all the samples were obtained by using a microwave-assisted hydrothermal synthesis method followed with the spark plasma sintering (SPS) process. First, a series of Cu3Sb1–xSnxSe4 (x = 0–0.03) compounds have been synthesized, and the hole carrier concentration obviously increased with increasing the Sn content. In addition, La doping subsequently was employed to the Cu3Sb0.98Sn0.02Se4 sample to further increase its power factor by band flattening, resulting in a typical high power factor of 1156.5 μWm–1 K–2 and zT of 0.67 in Cu3Sb0.92Sn0.02La0.06Se4 at 623 K. Our study provides a novel methodology through regulating its carrier concentration and band structure for designing high thermoelectric performance Cu3SbSe4-based materials.
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CELLULOSE
·
2020
·Vol. 27
·期 6
·3379-3390
·
IF 4.21
Zhang Yi,Zheng Xudong,Bian Tingting,Zhang Yuzhe,Mei Jinfeng,Li Zhongyu
Abstract The purpose of the paper is to achieve adsorption and secondary application of La(III) through strong coordination ability of phosphate groups and La(III). Firstly, cellulose nanocrystals (CNCs) were phosphorylated in two solvents (water and molten urea). p-CNC(water)/MWCNT and p-CNC(urea)/MWCNT thin films were successfully synthesized by using p-CNCs as film units based on EISA method. The addition of multi-wall carbon nanotube was to improve thermal stability and repeatability of films and carboxyl groups thereon could also involve in the coordination of La(III). Adsorption experiments show that, at pH 4.0, adsorption capacities of p-CNC(water)/MWCNT and p-CNC(urea)/MWCNT films were 21.23 and 44.71 mg g −1 , with half equilibrium time ( t 1/2 ) of 23.06 and 4.87 min. Repeatability tests show that the adsorption capacities of films remained above 82% of the maximum adsorption capacities after five adsorption–desorption cycles. Graphic abstract
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危险品化学品经营许可证（带存储）