Crystals
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2018
·Vol. 8
·期 3
·113
·
IF 2.144
Hui Wang,Qin Li,Chaoyue Wang,Huan He,Jianding Yu,Jiayue Xu
High-quality Ta-doped La2Ti2O7(Ta-LTO) single crystal of about 40 mm in length and 5 mm in diameter was successfully prepared by the optical floating zone method. An X-ray rocking curve reveals that the crystal of LTO has excellent crystalline quality. As-grown crystals were transparent after annealing in air and the transmittance is up to 76% in the visible and near-infrared region. X-ray diffraction showed that this compound possessed a monoclinic structure with P21space group. The dielectric properties were investigated as functions of temperature (0~300 °C) and frequency (102Hz~105Hz). Dielectric spectra indicated an increase in the room-temperature dielectric constant accompanied by a drop in the loss tangent as a result of the Ta doping. One relaxation was observed in the spectra of electric modulus, which was ascribed to be related to the oxygen vacancy. The dielectric relaxation with activation energy of 1.16 eV is found to be the polaron hopping caused by the oxygen vacancies.Keywords:Ta-LTO single crystal;floating zone method;dielectric properties;oxygen vacancy
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 10
·1695
·
IF 5.719
Haodong Wen,Wenning Zhao,Xiuxun Han
Layered perovskite-type semiconductor La2Ti2O7has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La2Ti2O7with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co3O4nanoparticles on the surface of n-type plate-like La2Ti2O7. The effects of Co3O4loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co3O4/La2Ti2O7possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co3O4exhibits the highest hydrogen evolution rate of 79.73 μmol·g−1·h−1and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co3O4ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La2Ti2O7-based heterojunctions for photocatalytic hydrogen evolution.Keywords:photocatalysis;hydrogen evolution;p-n heterojunction;La2Ti2O7;Co3O4
研究领域:
材料科学
·
光催化
·
能源材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTEGRATED FERROELECTRICS
·
2023
·
IF 0.7
Xiaoqian Lu,Peisong Tang,Jing Zhang,Huize Xu,Shiyu Wen,Yuebin Lou,Yuanyuan Liu,Haifeng Chen
Using lanthanum nitrate, butyl titanate and citric acid as the main raw materials, lanthanum titanate (La2Ti2O7) was successfully prepared by sol-gel method. The samples were characterized by thermogravimetric differential thermal analysis (TG-DTA), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Fourier infrared spectroscopy (FT-IR). Using 10 mg/L azo dye methyl orange solution as simulated sewage, the photocatalytic activity of La2Ti2O7 was studied by changing the synthesis temperature and light time under ultraviolet light. The results show that pure La2Ti2O7 samples can be obtained at 600 °C∼900 °C. SEM showed that La2Ti2O7 was dominated by irregular particles, and the average grain size was 4 ∼ 6μm. The La2Ti2O7 samples are consistent with approximation zero order kinetic for the degradation of methyl orange. The photocatalytic results showed that the photocatalytic activity of La2Ti2O7 prepared by calcination at 800 °C and 900 °C for methyl orange solution was significantly better than that of other temperature sections. The photocatalytic activity of La2Ti2O7 calcined at 900 °C was the best, and the degradation rate of methyl orange reached about 95% for degradation 60 min. This indicates that La2Ti2O7 is a novel photocatalyst with wide application prospects in the field of UV photocatalysis.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2024
·
IF 4.7
Lijiao Zhong,Xing Li,Yiquan Zhan,Yongsheng Liu,Kai Yang,Jinbiao Liu,Shiyong Liu,Junzhe Jiang,Liqing Li,Yoshihisa Sakata
Solar-driven hydrogen production through water splitting is currently one of the research hotspots nowadays. Lanthanum titanate (La 2 Ti 2 O 7 ) is one kind of layered-structure perovskite photocatalyst and possesses a superior electronic structure for photocatalytic overall water splitting. However, it suffers from several drawbacks, such as poor photo absorption and easy recombination of photogenerated charge carriers. In this study, sodium (Na) ion-doped La 2 Ti 2 O 7 with plate-like crystal morphology was synthesized by using molten salt synthesis (MSS). The XRD and TEM results indicated that the MSS method enhanced the crystallinity of La 2 Ti 2 O 7 . UV-vis, Raman and EPR spectra disclosed that Na doping through MSS introduced oxygen vacancies. The Na (0.3 mol%)-doped La 2 Ti 2 O 7 (MSS) provided the optimal hydrogen evolution rate, and the value was 6.43 times greater than that of pure La 2 Ti 2 O 7 synthesized by traditional solid-state reaction method. The synergistic effect of crystal facet engineering and defect engineering remarkably enhanced the photocatalytic activity of La 2 Ti 2 O 7 .
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS SCIENCE FORUM
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2016
·
IF 0
Ying Zhou,Zhi Yong Mei,Hai Shao Ye,Wen Wen Su,Xi Zhao,Pei Song Tang
Using La (NO3)3·6H2O, TiCl4 , and citric acid as the main raw materials, nanocrystalline La2Ti2O7 samples were prepared by microwave assisted method. The structure and morphology of samples were characterized by thermogravimetric and differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy. The photocatalytic activity of La2Ti2O7 was studied for methyl orange (MO) used as simulated sewage. It was found that the single phase La2Ti2O7 could be obtained through the calcination of microwave processed La2Ti2O7 precursors at 600 °C. The resulted product had an approximate spherical shape and average grain size of 50 nm in diameter. Under UV light, the photocatalytic experiment indicated that the prepared La2Ti2O7 nanocrystalline had high photocatalytic activity for degradation of methyl orange.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
KEY ENGINEERING MATERIALS
·
2014
·
IF 0
Gang Chen,Xiao Dong Peng,Chun Lin Deng,Chun Lin Fu,Wei Cai,Chun Yan Deng,Xiao Shuang Li
The La2Ti2O7+xwt%ZnO(x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were prepared by the conventional solid state reaction method, and effects of ZnO doped on the structure, dielectric and ferroelectric properties were investigated in detail. The X-ray diffraction patterns of La2Ti2O7 ceramics doped by ZnO oxide showed that no second phase exists. The surface morphology is palte-like shape, the grains of La2Ti2O7 ceramics increase with increasing the content of ZnO, and the result is to improve the density of La2Ti2O7 ceramics. The dielectric constant and loss decreases with increasing frequency.When the content of ZnO is more than 0.05wt%, the dielectric constant and loss decreases with the amount of addition of ZnO oxide increasing. The ferroelectric hysteresis loop is not saturable, which is attributed to its large leakage current. The ferroelectric properties improve with the addition of ZnO oxide. .
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Jian Qiao,Kehui Lin,Renqiang Shi
To improve the properties of SiC fiber-reinforced ceramic-matrix composites for potential use as radar-absorbing materials, La 2 Ti 2 O 7 interphase was dip-coated on the surface of the SiC fibers, and the SiC f /NBAS composites were then prepared. The pristine SiC fibers with relatively high electrical resistivity were mainly composed of amorphous Si x C y O and a small amount of β -SiC and free carbon. A weak La 2 Ti 2 O 7 interphase improved the flexural strength and toughness of the composites due to the fiber pull-out and crack deflection. The measured room-temperature complex permittivity of the composites increased, and the dielectric loss was greater than that of the pristine SiC fibers owing to the production of excess free carbon in the degradation of SiC fibers during the preparation of SiC f /NBAS composites. The excess free carbon with higher electrical conductivity was also believed to play a significant part in the increase of dielectric permittivity of the composites with the increasing heat-treatment temperatures even below 1000 °C. A dual-layer structure was designed to expand the bandwidth for microwave absorption.
研究领域:
材料科学
·
复合材料
·
电磁学
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2024
·
IF 3.5
Hanbing Wang,Yunqi Ning,Qi Tang,Xueyang Li,Mengdi Hao,Qun Wei,Tingting Zhao,Daqi Lv,Hongwei Tian
The layered perovskite lanthanum titanate (La2Ti2O7) is a good photocatalytic material owing to its high stability, strong redox ability, and non-toxicity. However, its inherent wide bandgap limits its application in photocatalytic hydrogen evolution. Therefore, combining La2Ti2O7 with two-dimensional (2D) narrow-bandgap semiconductors to form a 2D/2D layered structures is the preferred strategy to improve its photocatalytic performance. In this study, a novel 2D/2D ZnIn2S4/La2Ti2O7 Z-scheme heterojunction was prepared through the solvothermal method. The experimental results show that when the molar ratio of La2Ti2O7 to ZnIn2S4 is 1:4, the hydrogen evolution rate of the composite under ultraviolet-visible light reaches 6.97 mmol·g1·h1, which is 3.5 times higher than that of the pure ZnIn2S4. The results of the morphological characterization of the samples and the photoelectrochemical measurements show that channels for the rapid transfer of carriers are generated by the unique 2D/2D structure of these samples, and the separation and migration efficiency of the photogenerated carriers gets significantly improved due to the formation of the Z-scheme heterojunction. This study provides useful insight into the modulation of wide-bandgap semiconductors and the research on solar energy conversion.
研究领域:
材料科学
·
纳米技术
·
光催化
·
能源转换
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2022
·
IF 12.92
Ke Wang,Miao Cheng,Nan Wang,Qianyi Zhang,Yi Liu,Junwei Liang,Jie Guan,Maochang Liu,Jiancheng Zhou,Naixu Li
Ascribing to incremental fossil fuels emissions, the utilization and conversion of CO 2 and development of renewable energy is globally essential and significative. Ultrathin 2D/2D heterojunctions with fast photo-generated electrons transmission channels illustrate a better strategy to improve photocatalytic activity. Herein, combing La 2 Ti 2 O 7 with metallic few-layered Ti 3 C 2 MXene to construct inter-plane 2D/2D heterojunction was in situ self-assembled through solvothermal method. Benefiting from the advantages including stability, conductivity, abundant active sites and formation of Schottky junctions, as expected, the ultrathin 2D/2D La 2 Ti 2 O 7 /Ti 3 C 2 MXene nanosheets presented much improved photocatalytic ability for CO 2 reduction to CO and CH 4 , which is about 4.6 and 11.4 times higher than that of mechanical mixed La 2 Ti 2 O 7 and Ti 3 C 2 MXene. fs-TAS and XPS provided direct evidence that the prominence of La 2 Ti 2 O 7 /Ti 3 C 2 MXene in photocatalytic CO 2 reduction reaction over other opponents should be attributed to the synergetic effect of efficient charge carrier mobility and formed 2D/2D Schottky heterojunction interfacial contact between La 2 Ti 2 O 7 and Ti 3 C 2 MXene. Intermediates revealed by in-situ DRIFTS and corresponding atomic-level DFT calculations confirmed the mechanism, pathways and selectivity for photocatalytic CO 2 conversion. This work expanded promising prospects arouses new impetus for deepening the prehension of the mechanism of photocatalytic CO 2 reduction, designing and fabrication of Schottky heterojunctions for application in conversion and utilization of CO 2 .
研究领域:
材料科学
·
环境科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Manjing Tang,Zhi Tan,Jie Xing,Ning Chen,Hao Chen,Hongjiang Li,Jianguo Zhu
The study conducts an in-depth analysis of the role of the crystal phase and particle size of TiO 2 in the preparation of La 2 Ti 2 O 7 (LTO) ceramics via the conventional solid-state method. Comparative studies on crystal structure, micromorphology, electrical properties and mechanical properties were performed, revealing that the selection of TiO 2 raw materials greatly influences the structure and performance of LTO ceramics, resulting in significant differences in the grain sizes, electrical properties, and mechanical properties of the ceramics. Among the various TiO 2 sources, the LTO ceramics synthesized with nano-rutile TiO 2 exhibit superior overall performance. The smaller grain size of 1.43 nm for the ceramic and higher relative density of 98.27 %, significantly enhance their electrical and mechanical properties. The piezoelectric constant is 1.5 pC/N at room temperature and 1.4 pC/N after annealing at 1000 °C for 48 h. The high Curie temperature with 1450 °C, high resistivity with 3.93 × 10 6 Ω cm at 600 °C, high hardness of 9.89 GPa and small change in elastic modulus make it excellent candidates for high-temperature electronic component applications.
研究领域:
材料科学
·
陶瓷
·
固体物理
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2021
·
IF 3.512
Munan Lu,Yi Cao,Yufeng Xue,Wenfeng Qiu
A series of graphene oxide (GO)/lanthanum titanate (La2Ti2O7, LTO) fiber composites were prepared through a hydrothermal method. The LTO fibers were homogeneously dispersed between the GO sheets. The structure and micromorphology of the GO/LTO composites were systematically studied. The composite exhibited a high specific capacitance of 900.6 F g–1 at a current density of 1 A g–1 in the 1 M H2SO4 and 10 wt % sucrose aqueous solution as the electrolyte. With the extended potential window of 1.8 V, the fabricated asymmetric supercapacitor device delivered a maximum energy density of 94.0 Wh kg–1 at a power density of 750.1 W kg–1. The GO/LTO composites could be promising materials for energy storage.
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF RARE EARTHS
·
2023
·
IF 4.9
Guofang Zhang,Xu Jianyi,Sun Shilong,Li Yiming,Liu Zhuocheng,Guo Ruihua,Yang Zhiyong,Bai Lu,Zhang Yanghuan
Hydrothermal-sintering method was employed to obtain pure and Li, Co, Mn, Cu and Zn doped La 2 Ti 2 O 7 solid solutions. The substitution sites of doping ions are discussed. X-ray diffraction (XRD) results indicate that the doped ions were incorporated into the lattice of La 2 Ti 2 O 7 successfully. Transmission electron microscopy (TEM) measurements prove that the doped ions with smaller radius induce the contraction of lattice. The results of UV and photoluminescence (PL) tests show that the doped ions cause the red-shift of band gap energies and enhance the concentrations of oxygen vacancies and defects. The electrochemical hydrogen storage properties of the samples were measured at 303 and 333 K, respectively. The discharge capacities of the doped samples keep growing by increasing the cycle number at 333 K. Meanwhile, the doped samples possess better kinetic performances than the pure La 2 Ti 2 O 7 . Among the samples, the Mn, Co and Li ions doped samples exhibit better electrochemical hydrogen storage properties. The hydrogen storage properties are closely related with the characteristics of doped ions, crystallite sizes, the content of the oxygen vacancies and defects in the lattice of La 2 Ti 2 O 7 .
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）