JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2013
·
IF 3.172
Wei Li,Rui Gao,Min Chen,Shuxue Zhou,Limin Wu
In this paper, monodisperse poly(styrene-co-acrylmide) (PSAM)/Nb 2 O 5 hybrid hollow spheres were synthesized using a hollowing mechanism similar to the Kirkendall effect. When these hybrid hollow spheres were calcinated at different temperatures, totally different structures, pseudohexagonal TT phase hollow Nb 2 O 5 spheres, and orthorhombic T phase short rods were obtained. Both of them exhibited stronger photocatalytic activity than the commercial Nb 2 O 5 , especially the as-obtained Nb 2 O 5 hollow spheres displayed significantly enhanced photocatalytic property and auto-accelerated photocatalytic kinetics compared to the commercial TiO 2 (P25). Moreover, the Nb 2 O 5 hollow sphere-based nanofilm fabricated using oil–water interfacial self-assembly presented excellent UV photodetective performance.
研究领域:
材料科学
·
光催化
·
光电检测
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Advanced Science Letters
·
2012
·Vol. 10
·期 1
·274-278
·
IF 0
Liu Chenglu,Wang Fang,Zhou Zhiqiang,Jia Peiyun
YNbO4:Eu nano-phosphors were successfully prepared in NaNO3 molten salt. X-ray diffraction was used to characterize the structure of the samples. The results indicate that a suitable amount of NaOH in NaNO3 molten salt can effectively improve the crystallinity
of the samples annealed at same temperature; meanwhile, the elevation of annealing temperature increases the crystallinity, and transfers the crystalline phase from scheelite to fergusonite. The micrographs of transmission electron microscopy reveal that the grain size increases with the elevation
of annealing temperature. Upon excitation into the niobate groups at 260 nm, YNbO4:Eu nano-phosphors exhibit weak emission at 405 nm, originated from Nb–O charge transfer transition and the characteristic emission of Eu3+, which indicates there is an energy transfer
from niobate group to Eu3+. Monitored by emission of 615 nm, the excitation spectrum shows that the f-f transition of 7F0–5L6 at 396 nm is more intense than the Nb–O charge transfer band at 260 nm. This intense absorption at
396 nm make YNbO4:Eu nano-phosphors an excellent candidate of white light emitting diode.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yue Li,Feng-Qiang Xiong,Ruiling Ou,Lipeng Wan,Congling Yin,Ruxin Che,Minghui Yang
Highly crystalline (110) layered perovskite Sr 2 Nb 2 O 7 , (111) layered perovskite Sr 5 Nb 4 O 15 and complex perovskite Sr 4 Nb 2 O 9 were prepared by NaCl-KCl flux growth method from SrCO 3 and Nb 2 O 5 . This flux synthesis achieves single strontium niobate phase in contrast to mixed niobates from the solid state reaction with the same heating parameters. A little excess of Sr source was found to be required for the synthesis of Sr 5 Nb 4 O 15 and Sr 4 Nb 2 O 9 at elevated temperature due to slight evaporation. The three strontium niobates were converted to perovskite SrNbO 2 N via thermal ammonolysis under NH 3 flow at 900 °C. Post-wash treatment was performed to remove the byproduct SrO. This makes additional nanopores in SrNbO 2 N in the cases of Sr 5 Nb 4 O 15 and Sr 4 Nb 2 O 9 , and results in increasing surface areas of SrNbO 2 N with Sr:Nb ratios in the precursors (from 9.9 to 19.8 and 35.5 m 2 /g). On the other hand, the UV–Vis diffusion reflectance spectra reveal decreasing light absorption by defects in SrNbO 2 N in this order. This suggests fewer low-valent Nb defects in SrNbO 2 N prepared from precursor with higher Sr:Nb ratio. SrNbO 2 N prepared from Sr 4 Nb 2 O 9 would be advantageous for applications that require high surface area and low defect density of the material.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Jianwei Yuan,Kwame Nana Opoku,Pin Zhou,Jiaqing Cao,Yaorao Gao,Haoyang Peng,Baoliang Liu,Xiaohui Chen,Zhenwei Zhang,Fu Yang
The highly efficient green catalytic synthesis of jet fuel from low-chain biomass molecules is very attractive to afford sustainable development. Herein, ultrafine Ni nanoparticles assembled on Nb 2 O 5 nanofibers were constructed and effectively utilized in the reductive coupling of n-octanoic acid, offering a novel approach distinct from traditional hydrogenation methods for fatty acids. During the process, a synergistic effect was observed between the metallic Ni phase and the fibrous Nb 2 O 5 , facilitating immediate ketonization following reduction. This enabled the conversion of n-octanoic acid into pentadecane, a crucial component of aviation kerosene. The key factor driving this conversion was the attainment of a production rate of 8-pentadecanone higher than that of n-octane, particularly under optimal conditions, resulting in a significant yield of pentadecane. The catalytic assessment results show that adjusting Ni loading altered the performance of the catalyst in which 1.0 % Ni/Nb 2 O 5 afforded the best catalytic activity. By precisely controlling the reaction temperature at 300 °C and maintaining a hydrogen pressure of 1 MPa, an impressive pentadecane yield of 70.5 % was achieved. This innovative approach, which combines reduction with ketonization, offers a promising strategy for producing long-carbon chain alkanes from short-carbon chain fatty acids within a single reactor. This not only reduces economic costs but also streamlines overall processes, presenting a significant advancement in sustainable fuel production.
研究领域:
催化化学
·
绿色能源
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2024
·
IF 3.3
Chenwei Xiong,Rui Hao,Kewen Tao,Huashan Li,Shaopeng Lin,Decai Ma
This study has demonstrated that lithium niobate doped with praseodymium (LiNbO 3 :Pr), which initially did not exhibit persistent luminescence(PersL), can display significant PersL performance through the modulation of the lithium-to-niobium ratio (R LN ). By adjusting the R LN to 1, LiNbO 3 :Pr achieved enhanced PersL, lasting several minutes, with the afterglow's duration further influenced by the R LN . Thermoluminescence (TL) assays and energy diagram analyses have elucidated that the presence and depth of oxygen vacancy defects are critical for both the emergence and longevity of PersL LiNbO 3 :Pr polycrystals . These insights enhance the understanding of PersL mechanisms in lithium niobate crystals and highlight their potential for application in optical information storage.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Liujia Tian,Fan Peng,Xuemei Song,Wei Zheng,Ziwei Liu,Yiling Huang,Yi Zeng
High-entropy rare-earth niobates have garnered significant attention in the field of thermal barrier coatings (TBCs) due to their ultra-low thermal conductivity. However, the exceptional thermal properties of fluorite-phase high-entropy rare-earth niobates and the outstanding mechanical properties of monoclinic-phase high-entropy rare-earth niobates cannot be simultaneously harnessed. To address this limitation, this paper investigates and synthesizes five single-phase high-entropy rare-earth niobates: (RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 ) 3 NbO 7 (RE = Ce, Sm, Eu, Dy, Lu), and five composite-phase high-entropy rare-earth niobates with a molar ratio of (RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 )NbO 7 : (RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 )NbO 4 = 1:2 (RE = Ce, Sm, Eu, Dy, Lu). The objective is to fabricate niobate coatings that exhibit both outstanding thermal and mechanical properties. The test results reveal that the intrinsic thermal conductivity of the composite-phase samples stands at a mere 1.46 W m −1 ·K −1 at 1000 °C. Comparatively, the experimental thermal conductivity of the single-phase samples slightly surpasses that of the composite-phase at 1000 °C, registering a minimum of 1.57 W m −1 ·K −1 . Importantly, both values adhere to the TBC standard. The mechanisms behind the low thermal conductivity of the composite-phase and single-phase samples are elucidated by the phonon scattering mechanism and the Cahill model, respectively. Furthermore, the thermal expansion coefficient of the composite-phase samples exceeds that of the single-phase samples overall, and they demonstrate exceptional mechanical properties, offering nearly twice the fracture toughness of the single-phase samples while maintaining high hardness. Experimental evidence shows that composite-phase niobates exhibit enhanced thermodynamic properties compared to single-phase niobates. This work serves as a valuable reference for the utilization of high-entropy rare-earth niobates in the realm of thermal barrier coatings.
研究领域:
材料科学
·
热力学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2023
·
IF 5.5
Huifang Liu,Chengpeng Liu,Ni Zhen,Jing Dong,Yingnan Chi,Changwen Hu
Recently, Pickering emulsions provide a green and efficient solution for interfacial catalysis. However, in an emulsion system the separation of products and the recycle of catalysts rely on time- and energy-consuming centrifugation and filtration. Herein, a straightforward emulsion assisted assembly strategy has been developed to fabricate amphiphilic polyoxoniobates (PONbs), [C n H 2n+1 N(CH 3 ) 3 ] 6 KHNb 6 O 19 /SiO 2 (C n -Nb 6 /SiO 2 ; n = 14, 16, and 18). The honeycomb-like C 16 -Nb 6 /SiO 2 composite not only can form stable Pickering emulsion in the n-octane/water system but also can effectively catalyze oxidative desulfurization under mild conditions. Notably, after the reaction, the oil phase and the emulsion phase were automatically separated: the clean oil was collected by decantation, while the recycled emulsion was directly used for the next run. Moreover, C 16 -Nb 6 /SiO 2 is highly robust and can be consecutively used for up to eleven cycles with negligible loss of its catalytic activity.
研究领域:
化学工程
·
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Xiaoge Peng,Zhikang Bao,Shijie Zhang,Yuanan Li,Lei Ding,Huaijie Shi,Jia Liu,Xing Zhong,Xiaonian Li,Jianguo Wang
Assembling two desirable half-reactions of green oxidants hydrogen peroxide (H 2 O 2 ) and ozone (O 3 ) into efficient paired electrolysis is highly valuable in terms of efficiency and environmental-friendliness. However, rational design and construction of electrocatalysts with regulable active sites for the paired electrosynthesis of green oxidants of H 2 O 2 and O 3 remain a significant challenge. Herein, A new strategy was developed for tunning the active sites of pseudo-hexagonal centers (TT, Lewis acid sites) and orthogonal centers (T, Brønsted acid sites) in Mxene layered structure niobium pentoxide (Nb 2 O 5 ) with abundant oxygen vacancy (O V ) for the paired electrolysis of 2e - oxygen reduction reaction (ORR) and electrochemical ozone production (EOP). The TT-300 and T-400 electrocatalysts exhibited outstanding electrochemical activity of 2e - ORR (H 2 O 2 selectively of 92% at 0.4 V RHE ) and EOP (gaseous ozone FE of 13% at 50 mA cm −2 ), respectively. The excellent performance was mainly attributed to the TT-300 (Lewis acid sites) and T-400 (Brønsted acid sites) with abundant O V that improve the oxygen-containing intermediates formation of OOH* and deprotonation of water. In addition, the in-situ electro-degradation of organic compounds experiments indicated that the synergistic degradation of O 3 and H 2 O 2 possessed a faster kinetic constant compared with a single electrolysis system of O 3 and H 2 O 2 . The work provides meaningful insights into the rational design and construction of advanced solid acid electrocatalysts for efficient simultaneously electrocatalytic hydrogenation and oxidation to produce green oxidants of O 3 and H 2 O 2 .
研究领域:
材料科学
·
电化学
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2024
·
IF 6.2
Liujia Tian,Yiling Huang,Xuemei Song,Fan Peng,Wei Zheng,Ziwei Liu,Yi Zeng
This study reports the preparation of two single-phase high-entropy rare-earth niobates (RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 ) 3 NbO 7 , (RE = Ce, Lu), and two composite-phase high-entropy rare-earth niobates (RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 ) 3 NbO 7 :(RE 1/5 Ho 1/5 Er 1/5 Y 1/5 Yb 1/5 )NbO 4 = 1:2, (RE = Ce, Lu) via solid-phase synthesis. The interactions of these samples with molten calcium-magnesium-aluminum-silicates (CMAS) were studied at 1300 °C to explore their performance and mechanism in CMAS corrosion. The results indicate that the corrosion process involves the phase transformation of RE 3 NbO 7 and the formation of apatite products. The Ce-composition sample exhibits superior performance in terms of reaction layer thickness, remaining CMAS thickness, and RE 3+ content in the remaining CMAS. These findings underscore the potential application of high-entropy rare-earth niobates in thermal barrier coatings (TBCs) and contribute to understanding niobate system resistance to CMAS corrosion.
研究领域:
材料科学
·
腐蚀与防护
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2024
·
IF 9.3
Jie Li,Pengpeng Shao,Weijie Geng,Peng Lei,Jing Dong,Yingnan Chi,Changwen Hu
The oxidative depolymerization of β-O-4 linkages into value-added aromatic chemicals is of great importance for lignin valorization. However, achieving highly selective and rapid cleavage of β-O-4 linkages under mild conditions remains a challenge. Herein, cobalt–cobalt oxides (Co-CoOx) supported on N-doped carbon (CoMA/C900) combined with a green and recyclable base K7HNb6O19 (KNb6) have shown remarkable activity for the one-step oxidative cleavage of lignin β-O-4 linkages. Under relatively mild conditions (100 °C, 0.2 MPa O2), a lignin β-O-4 alcohol model compound was almost completely converted within 3 h, affording a narrow product distribution of phenol (yield: 99%) and methyl benzoate (yield: 98%). Based on the control experiments, kinetic study, and spectroscopic analysis, a synergistic oxidative cleavage mechanism was proposed: CoMA/C900 activates molecular oxygen to form a superoxide radical, while basic KNb6 promotes deprotonation of secondary alcohol, and they synergistically catalyze the oxidation of β-O-4 alcohol and the rapid cleavage of Cβ–O and Cα–Cβ bonds. During the reaction, the oxidation of β-O-4 alcohol to β-O-4 ketone is the rate-determining step, while the cleavage of PP-one to phenol and methyl benzoate can be completed within 15 min. Moreover, the CoMA/C900–KNb6 catalyst is recyclable at least three times and highly active for the oxidative cleavages of other lignin models and organosolv birch lignin.
研究领域:
化学工程
·
材料科学
·
生物质转化
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2020
·
IF 4.495
Jing Wang,Xinhong Wan,Yu Rao,Lei Zhao,Kongjun Zhu
Silver niobate AgNbO 3 ceramics have been regarded as a promising lead-free material for energy storage applications. In present work, pure and fine AgNbO 3 powders were successfully fabricated via the hydrothermal method using AgNO 3 as the raw material. It is found that the reaction products show strong dependence on the molar ratio of NH 4 HF 2 :AgNO 3 :Nb 2 O 5 , pH value and reaction time. Pure AgNbO 3 powders were obtained when the process conditions are 3NH 4 HF 2 :2AgNO 3 : x Nb 2 O 5 with x ≤0.85 or y NH 4 HF 2 :2AgNO 3 :1Nb 2 O 5 with y = 4–5, pH = 5 and reaction time t ≥ 10 h. Benefitting from the hydrothermal synthesised AgNbO 3 powders, AgNbO 3 ceramics with fine-grain of ∼3.4 μm were obtained. The fine-grain leads to increased electric breakdown strength E b up to 250 kV/cm, which is the highest among the pure AgNbO 3 ceramics to our best knowledge. The further enhancement in E b and recoverable energy density could be highly anticipated if the antiferroelectric phase could be stabilized.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Qian Dai,Bingnan Yuan,Minghui Guo,Kun Zhang,Xueqi Chen,Zihui Song,Tat Thang Nguyen,Xiaojing Wang,Shudong Lin,Jincheng Fan,Yingchun Li,Hu Liu,Zhanhu Guo
To improve the photocatalytic efficiency of niobium pentoxide (Nb 2 O 5 ) for the degradation of organic pollutants, a novel nano-fibriform C-modified Nb 2 O 5 (F–C/Nb 2 O 5 ) photocatalyst was successfully synthesized by niobium oxalate as precursor and nanofibrillated cellulose (NFC) as template and carbon source. Vacuum induced self-assembly method was used to form the nano-fibriform morphology. Compared to ordinary C/Nb 2 O 5 and commercial Nb 2 O 5 , F–C/Nb 2 O 5 exhibited a typical three-dimensional nanorod structure with plenty of pores. The specific surface area of F–C/Nb 2 O 5 was 3 times that of C/Nb 2 O 5 . The prepared F–C/Nb 2 O 5 exhibited a 3.01 eV bandgap and was able to be activated under visible light while that was unable for commercial Nb 2 O 5 with 3.19 eV bandgap. The F–C/Nb 2 O 5 showed the best photocatalytic efficiency in pH value ≤ 3. After cycling for 5 times, the photocatalytic efficiency of F–C/Nb 2 O 5 was still 2.4 times of the ordinary C/Nb 2 O 5 under visible light. Meanwhile, the self-assembly mechanism and photodegradation mechanism were proposed. This study provides a new strategy to form a special nano-fibriform C-modified niobium pentoxide with extremely high photocatalytic efficiency in aqueous solutions.
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
危险品化学品经营许可证（带存储）