CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yu Zeng,Chenhan Xiong,Jingxuan Li,Zhiyong Huang,Guoping Du,Zhaoyang Fan,Nan Chen
Ceramic/polymer composites have great potential to achieve the concomitant enhancement of both dielectric constant and breakdown field while maintaining other superior properties of the polymer matrix , ideal for elastomer sensors, actuators, capacitive energy storage, and many other applications. However, material incompatibility between the ceramic filler and the polymer matrix often leads to void formation , particle aggregation and phase separation, with significantly degraded performance. Herein, through surface modification, co-doped TiO 2 particles were uniformly dispersed and bridged onto the silicone rubber matrix via a silane coupling agent for fabricating composites via mechanical mixing and hot-pressing. The synthesized composites exhibit enhanced dielectric constant, increased from 2.78 to 5.06 when 50 wt% co-doped TiO 2 particles are incorporated. Their dielectric loss is less than 0.001 in a broad frequency range. Theoretical modelling and experimental results reveal that the morphology and dispersion state of co-doped TiO 2 particles were crucial to the dielectric properties of the silicone rubber-based composites. Besides, the composites are thermally stable up to 400 °C. Significantly increased tensile strength (612 kPa) and elongation at break (330%) were obtained for the composite incorporated with 30 wt% co-doped TiO 2 particles, accompanied by a moderate increased elastic module (540 kPa). Such composites have the potential for different applications.
研究领域:
材料科学
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电气工程
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产品关联
DOI
高影响因子
iScience
·
2023
·
IF 5.8
Ying Zhang,Yuying Wan,Xiaoxu Liu,Kai Chen,Ke Chu
Electrocatalytic reduction of nitrite to ammonia (NO 2 RR) is considered as an appealing route to simultaneously achieve sustainable ammonia production and abate hazardous nitrite pollution. Herein, atomically Nb-doped NiO nanoflowers are designed as a high-performance NO 2 RR catalyst, which exhibits the highest NH 3 -Faradaic efficiency of 92.4% with an NH 3 yield rate of 200.5 μmol h -1 cm -2 at -0.6 V RHE. Theoretical calculations unravel that Nb dopants can act as Lewis acid sites to render effective NO 2 - activation, decreased protonation energy barriers, and restricted hydrogen evolution, ultimately leading to a high NO 2 RR selectivity and activity.
研究领域:
材料科学
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环境科学
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催化化学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Xuansheng Wang,Muzi Liu,Tian Tian,Fang Liu,Jiali Wang,Jinping Li,Guang Liu
MgH₂ is recognized as one of the most promising solid hydrogen storage materials; however, its practical application is confined by sluggish kinetics and stable thermodynamics. In this study, fibrous VNbO₅ was synthesized via electrospinning and subsequently introduced into MgH₂ through ball milling technology to enhance hydrogen storage properties. The addition of 7 wt% VNbO₅ give rise to the obvious decline in the initial dehydrogenation temperature of MgH₂, from 322.2 °C to 200.2 °C. At 300 °C, the modified composite exhibited rapid dehydrogenation, releasing approximately 6.43 wt% hydrogen within 8.1 min. Moreover, the fully dehydrogenated sample demonstrated the ability to absorb hydrogen at room temperature and absorbed 6 wt% H₂ at 200 °C within 16 s. The desorption activation energy of the MgH₂-7 wt% VNbO₅ composite was determined to be 75.32 ± 1.44 kJ/mol, representing an approximate 48.1% reduction compared to the 145.25 ± 2.14 kJ/mol of pure MgH₂. Furthermore, the system possessed remarkable cyclic stability, retaining 95.5% of hydrogen storage amount after 20 cycles. During the reaction process, VNbO₅ decomposed into low-valence state active catalytic species, including Nb₂O₅, NbO, Nb, VO₂, and V. The in-situ generation of this multi-element, multi-valence chemical environment synergistically enhanced hydrogen storage performance of MgH₂.
研究领域:
材料科学
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能源存储
✓ 已验证
DOI
高影响因子
Materials
·
2021
·Vol. 14
·期 9
·2426
·
IF 3.623
Xiaoyuan Fan,Peng Du,Xiaoxuan Ma,Ruyue Wang,Jingteng Ma,Yonggang Wang,Dongyu Fan,Yuanzheng Long,Bohan Deng,Kai Huang,Hui Wu
Production of hydrogen from water splitting has been considered as a promising solution for energy conversion and storage. Since a noble metal-based structure is still the most satisfactory but scarce kind of catalyst, it is significant to allow for practical application of such catalysts by engineering the heterogeneous structure and developing green and facile synthetic strategies. Herein, we report a mechanochemical ball milling synthesis of platinum nanoclusters immobilized on a 2D transition metal carbide MXene (Nb2CTx) as an enhanced catalyst for hydrogen evolution. After annealing at 600 °C, ultrafine Pt3Nb nanoclusters are formed on the Pt/Nb2CTxcatalyst. As prepared, the Pt/Nb2CTx-600 catalyst demonstrates superior electrochemical HER activity and stability with an ultralow overpotential of 5 mV and 46 mV to achieve 10 mA cm−2and 100 mA cm−2, respectively, in comparison with other Nb2CTx-based catalysts and commercial Pt/C catalysts. Moreover, the remarkable durability is also confirmed by accelerated durability tests (ADTs) and long-term chronoamperometry (CA) tests. The excellent HER performance was attributed to high Pt dispersion and more active site exposure by the mechanochemical process and thermal treatment. Such results suggest that the mechanochemical strategy provides a novel approach for rational design and cost-effective production of electrocatalysts, also providing other potential applications in a wide range of areas.Keywords:hydrogen evolution;Pt-Nb alloy;mechanochemical synthesis;thermal annealing
研究领域:
材料科学
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电催化
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产品关联
DOI
PubMed
高影响因子
Sustainable Energy & Fuels
·
2018
·Vol. 2
·期 7
·1530-1541
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IF 0
Xincheng Wang,Yongji Song,Chongpin Huang,Bin Wang
Lactic acid (LA) is a versatile platform chemical for the production of biodegradable polymers as well as starting materials for the pharmaceutical industry. In this study, crystalline niobium phosphates directed by various surfactants were prepared by a facile sol–gel method and studied as heterogeneous Lewis acid catalysts for the direct conversion of triose sugars to LA under aqueous conditions. Metal oxides were used to alter the surface acidity, and pyridine FTIR analyses demonstrated the presence of both Lewis and Brønsted acid sites, which played essential roles in the conversion of biomass sugars. The incorporation of SnO2 and the use of surfactants significantly lowered the Brønsted-to-Lewis site ratio. P–OH groups were determined to be the origin of the Brønsted acid sites, while the partially hydrolyzed framework of tin and niobium species led to the formation of Lewis acid sites. The cationic surfactant-modified samples with highly crystalline structures outperformed the amphiphilic surfactant-modified samples. The optimum cetyltrimethylammonium bromide-modified catalyst afforded an LA yield of ca. 92% with the complete dihydroxyacetone (DHA) conversion at 160 °C. Furthermore, the isomerization of pyruvaldehyde (PA) was found to be the rate-determining step, while the rehydration of PA to DHA could occur in the current reaction system. A possible reaction mechanism involving the evolution of two key catalytic intermediates was proposed. In addition, crystalline niobium phosphates were also effective in the aqueous dehydration of sugars to furan derivatives with a 44% 5-hydroxymethylfurfural yield from glucose after 1 h. The current study can hopefully serve as a model for the development of novel solid acid catalysts for the conversion of sugars to platform chemicals.
研究领域:
化学工程
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催化科学
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生物质转化
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产品关联
DOI
Scientific Reports
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2021
·Vol. 11
·期 1
·1-11
·
IF 4.38
Wang Jingfeng,Zhang Yue,Liu Fang,Li Qingkui
Considering the problem of high oxygen content in industrial niobium powder, the oxygen reduction of high oxygen niobium powder with the addition of magnesium is studied. Based on the thermodynamic analysis of magnesium thermal reduction of niobium powder, the effects of reduction temperature, magnesium addition, reduction time, and reduction atmosphere on the oxygen content of pickling niobium powder are studied. The results show that with an increase in the magnesium addition, the oxygen content of pickling niobium powder gradually decreases to a certain value, and then remains unchanged. In a certain temperature range (953–1203 K), with an increase in the reduction temperature, the oxygen content of pickling niobium powder first decreases, and then increases; the best oxygen content is 356 ppm at 1133 K. With the extension in reduction time (2–6 h), the oxygen content of pickling niobium powder first decreases, and then remains unchanged. Finally, the oxygen content of pickled niobium powder is reduced to approximately 356 ppm at 400% magnesium addition at 1133 K for 4 h.
研究领域:
材料科学
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冶金学
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产品关联
DOI
PubMed
高影响因子
Materials
·
2022
·Vol. 15
·期 19
·6929
·
IF 3.748
Shenghao Li,Xiaohuan Wang,Zhiming Shi,Jun Wang,Guojun Ji,Xinba Yaer
Ferrous titanate (FeTiO3) has a high theoretical capacity and physical and chemical properties stability, so it is a potential lithium anode material. In this study, FeTiO3nanopowder and nanosheets were prepared by the sol–gel method and the hydrothermal method. In addition, niobium-ion doping was carried out, the radius of Nb close to Ti so the Nb can easily enter into the FeTiO3lattice. Nb can provide more free electrons to improve the electrochemical performance. Then, the effects of the morphology and niobium doping on the microstructure and electrochemical properties of FeTiO3were systematically studied. The results show that FeTiO3nanosheets have a better lithium storage performance than nanopowders because of its high specific surface area. A certain amount of niobium doping can improve the electrochemical performance of FeTiO3. Finally, a 1 mol% niobium-doping FeTiO3nanosheets (1Nb-FTO-S) electrode provided a higher specific capacity of 782.1 mAh g−1at 50 mA g−1. After 200 cycles, the specific capacity of the 1Nb-FTO-S electrode remained at 509.6 mAh g−1. It is revealed that an increased specific surface area and ion doping are effective means to change the performance of lithium, and the proposed method looks promising for the design of other inorganic oxide electrode materials.Keywords:FeTiO3;niobium doping;microstructure;lithium storage performance
研究领域:
材料科学
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电化学
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产品关联
DOI
PubMed
高影响因子
Catalysts
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2020
·Vol. 10
·期 12
·1480
·
IF 3.52
Wei Guo,Libin Yang,Jinghao Lu,Peng Gao,Wenjing Li,Zhiying Feng
To effectively improve photocatalytic activity, the morphology and crystallinity of semiconductor photocatalysts must be precisely controlled during the formation process. Self-aligned Nb2O5nanotube arrays have been successfully fabricated using the electrochemical anodization method. A novel growth mechanism of Nb2O5nanotubes has been proposed. Starting from the initial oxidation process, the “multi-point” corrosion of fluoride ions is a key factor in the formation of nanotube arrays. The inner diameter and wall thickness of the nanotubes present a gradually increasing trend with increased dissociative fluorine ion concentration and water content in the electrolyte. With dehydroxylation and lattice recombination, the increased crystallinity of Nb2O5represents a reduction of lattice defects, which effectively facilitates the separation and suppresses the recombination of photo-generated carriers to enhance their catalytic degradation activity.Keywords:Nb2O5;nanotube;growth mechanism;crystalline;photocatalysis
研究领域:
材料科学
·
环境科学
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DOI
高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 23
·14244-14252
·
IF 10.733
Zeyi Wang,Xuelian Zhang,Zhuanghe Ren,Yong Liu,Jianjiang Hu,Haiwen Li,Mingxia Gao,Hongge Pan,Yongfeng Liu
A novel 2D layered NbTiC solid-solution MXene was synthesized from its MAX phase via a wet chemical etching process. While ball milling the NbTiC MXene with MgH2, ultrafine bimetal NbTi nanocrystals were formed in situ with a grain size of 5 nm, which offer highly stable catalytic activity for the hydrogen storage reaction of MgH2. The MgH2-9 wt% NbTiC sample starts releasing hydrogen from 195 °C, which is 80 °C lower than that for the additive-free sample. At 250 °C, it releases approximately 5.8 wt% H2 within 30 min, and the fully dehydrogenated sample takes up 4.0 wt% H2 within 15 min even at 50 °C under 50 bar H2 pressure. DFT calculations reveal a charge transfer process from Ti atoms to Nb atoms in the NbTi cluster and a lower absolute value of the adsorption energy of H2 on NbTi. This would presumably benefit both the breakage of Mg–H bonding and the detachment of H2 from the NbTi surface, and consequently lead to good catalytic activity.
研究领域:
材料科学
·
能源科学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2024
·
IF 10.7
Yuhui Huang,Yehan Tao,Qingqing Wang,Jian Du,Jinwen Hu,Jie Lu,Yanna Lv,Haisong Wang
To develop an industrial zeolite-based catalyst for efficient furfural production, the acidity, pore structure, and electronic properties of H-β zeolite were modulated by synergistic deatomization and atomic implantation treatments. The dealumination effectively decreased the intrinsic aluminum-related Lewis and Brosted acid sites, thus decreasing the occurrence of unwanted side reactions. Meanwhile, the removed skeleton aluminum can create voids for the following atomic implantation of introducing higher valent-state niobium species, which would provide new kinds of catalytic active sites, increase the average pore size by distorting the zeolite skeleton, and enhance the interaction with reactant molecules by acting as more electron deficient centers. In a single-phase water/γ-valerolactone reaction system, the optimum catalyst can efficiently convert both xylan and xylose with a conversion of 100 % at a medium temperature of 130 ℃ within 3 hours. Compared with the furfural yield over untreated H-β (12.7%), the yield over deAlβ/Nb(20%) catalyst was greatly enhanced by 54% with xylose as raw material. The catalyst can be recovered by simple cleaning and thermal regeneration and then reused. The proposed post-treatment strategy could maintain the integrity of the zeolite structure, ensure uniform and stable metal dispersion under harsh conditions, manage the complexity and cost of the preparation process, and most importantly, optimize the catalytic performance. Addressing these issues is essential for improving the efficiency and practical application of industrial zeolite catalysts by this general approach and benefiting industrial furfural production.
研究领域:
化学工程
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催化材料
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2024
·
IF 13.3
Seokyoung Choi,Wuliang Feng,Zhongzhu Liu,Yongyao Xia
Spinel LiMn 1.5 Ni 0.5 O 4 (LMNO) is one of the promising cathode materials for the next generation Li-ion batteries due to its voltage platform. However, the dissolution of the transition metal at high voltage is the biggest obstacle that LMNO suffers from. In this study, we successfully suppressed transition metal dissolution in LMNO by the morphology control from regular octahedron to spherical. Niobium was integrated as a dopant, which restricted the growth of (1 1 1) crystal face, and increased the indices of crystal faces by homogenizing the surface energy. By changing to a smaller surface area with spherical morphology, the contact area with the electrolyte was reduced, thus suppressing the dissolution of the Mn ion. Consequently, the niobium-doped LMNO exhibited superior rate performance, capacity retention with 74.1% at 1C after 500 cycles in half-cell, and thermal stability compared to pristine LMNO.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Yue Zhao,Shan Ni,Yafeng Liu,Wenjie Wang,Yuan Meng,Huifang Xing,Huizhou Liu,Liangrong Yang
To address the environmental and resource challenges arising from the advancement of the nuclear power industry, it becomes imperative to foster the development of efficient and expeditious materials for uranium adsorption. Here, for the first time, a kind of niobium phosphate with improvement of interlayer spacing and hydrophilicity (NbP-8) is employed by crystal phase modulation for uranium adsorption, which synergistically realizes structural and interfacial microenvironment modulation. Characterizations demonstrate that the expanded interlayer spacing contributes to accommodation of uranyl which increases adsorption capacity, and the enhanced hydrophilicity reduces infiltration time and greatly accelerates the adsorption rate. Consequently, NbP-8 possesses exceptional adsorption capacity of 1470.4 mg g −1 , ultra-fast adsorption rate with an equilibrium time of 1 min and high selectivity, delivering one of the best phosphate uranium adsorbents. Moreover, this work opens a new venue for optimizing performance of phosphate by changing the crystal phase to modulate structure and interfacial microenvironment for uranium adsorption.
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）