HIGH PERFORMANCE POLYMERS
·
2023
·
IF 2.1
Wenchao Zhang,Qiang Fu,Qixin Yuan,Han Li,Dong Yue,Yu Feng,Qingguo Chen,Jinghua Yin
Polyimide (PI) film have been synthesized and used extensively in energy transmission, wind power generation, new energy vehicles, lidar, and high-power weapons, et al. Nevertheless, it is still challenge to further improve the breakdown strength and dielectric constant of PI film. After the powders of Al0.5xNb0.5xSi1-xO2 (NASO (x mol%)) have been fabricated, it was analyzed that the effect of doping elements Al3+ and Nb5+ on the surface chemistry and microstructure of the NASO powder. And then a small amount of NASO powder was polymerized in situ with PI matrix material, and the effects of NASO on dielectric properties and breakdown strength of the NASO/PI composites were analyzed. The results showed that the introduction of the doping elements Al3+ and Nb5+ favors could be conductive to the formation of oxygen vacancies on the surface of the NASO particle, which improved the surface activity and chemical reactivity of the NASO particle. The PI matrix can efficiently capture additional charges and enhance the insulating characteristics of the NASO/PI composite by properly doping NASO fillers with specific defect concentrations. In the results the breakdown strength of 1 vol% NASO (1 mol%)/PI composites reaches 334.38 kV/mm, which is a 19.6% higher than that of PI. Because the traps in the fillers capture and suppress the carrier transport to enhance the insulating properties of the composites. This work offers a novel synthesis method to simultaneously produce polymer dielectrics with high insulation and high polarization.
研究领域:
材料科学
·
电气工程
✓ 已验证
DOI
高影响因子
APPLIED PHYSICS LETTERS
·
2024
·Vol. 124
·期 6
·
IF 3.5
Li Hao,Wu Hao,Wang Zhiguo,Xie Zhengqiu,Shu Shengwen,Liu Zhiyong,Ke Shanming,Shu Longlong
Donor doping can increase the dielectric constant of a material by several orders of magnitude due to induced space charge causing interfacial polarization. Giant dielectric properties and interface polarization are also both expected to greatly enhance the flexoelectric behavior of a material. In this work, a typical flexoelectric ceramic material, BaTiO 3 , was selected and donor doped using elemental Nb. Compared with the nominal BaTiO 3 ceramic, the dielectric constant and flexoelectric coefficient of the Nb-doped BaTiO 3 ceramics were significantly improved. The transverse flexoelectric coefficient of 0.3 mol. % Nb-BaTiO 3 was found to increase to nearly 40 times the nominal value, reaching 387 μ C/m. The results indicate that the giant dielectric response, and therefore the giant flexoelectric response, is the result of the combined effects of internal barrier-layer capacitance and surface barrier-layer capacitance. This study not only deepens the understanding of the semiconductor macro-dielectric effect and the flexoelectric mechanism caused by doping, but it also provides a feasible strategy for the design of giant dielectric/flexoelectric response materials and related devices with high dielectric constants and flexoelectric coefficients.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 46
·24598-24607
·
IF 11.301
Chizhong Wang,Rong Wang,Yue Peng,Jianjun Chen,Zhen Chen,Haibo Yin,Junhua Li
Development of new groups of oxygen evolution reaction (OER) electrocatalysts based on transitional metal materials is highly attractive for renewable energy conversion and storage. Here we report a new FeNb (oxy)hydroxide catalyst, which delivered a high OER activity with an overpotential as low as 0.34 V (at 10 mA cm−2). To attain a homogeneous mixing of metal components, niobium was initially incorporated into the framework of iron oxalate dihydrate. The mixed oxalate could be structurally transformed into short-range ordered (oxy)hydroxide, the reactive species for the OER. Incorporation of Nb has been demonstrated to improve the intrinsic OER activity based on Fe species and to accelerate the charge-transfer kinetics across the solid-electrolyte interface. It is also found that strong Fe–Nb interaction can induce the formation of high-valent Fe species. Theoretical calculation results further illustrate the role of NbOx in the OER mechanism, in which Fe serves as the active site and the Nb species can promote the conversion of *OH to *O intermediates to reduce the OER overpotential.
研究领域:
材料科学
·
电化学
·
可再生能源
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2026
·
IF 9.6
Lishuang Xu,Fangkun Li,Junxia Meng,Wenzhuan Hu,Jujun Yuan,Jie Huang,Dezhi Yan,Quanxin Ma,Puheng Yang,Jun Liu
Li-rich layered oxides (LLOs) offer a high reversible capacity, however, their commercial application is seriously impeded by rapid voltage decay and capacity degradation. Increasing Ni content in LLOs materials is regarded as a viable strategy to address this issue and has attracted current research interests but is normally accompanied by inferior cycling stability and reduced capacity. Herein, an effective strategy is proposed to enhance the performance of high‑nickel lithium-rich Mn-based oxides Li 1.13 Mn 0.48 Ni 0.33 Co 0.06 O 2 (LLMO) through Nb doping. Specifically, the optimized Ni excess cathode LLMO-Nb3 furnishes discharge capacities and energy densities of 199 mAh g −1 and 222 Wh kg −1 compared to 125 mAh g −1 and 136 Wh kg −1 of pristine LLMO after 200 cycles at 1.0C. The robust Nb O bonds and the pillaring effect of inactive Nb are capable of effectively stabilizing the oxygen lattice framework as well as suppressing the capacity and voltage fading upon cycling; the LLMO-Nb3 material achieves an impressive capacity retention of 91.46% after 300 cycles at 0.5C and 94.86% after 200 cycles at 1.0C as well as exhibits a superior midpoint voltage attenuation of 0.8 mV per cycle over 200 cycles at 1.0C. Concurrently, the cathode electrolyte interfacial (CEI) stability is improved by this synergistic regulation strategy combining increased Ni content with Nb doping, thus preventing the rapid performance decay of LLMO. This study proposes a novel strategy for fabricating high-performance high‑nickel Li-rich cathodes by doping proper alien elements, providing valuable guidance for the design of advanced cathode materials targeting high energy density lithium-ions batteries.
✓ 已验证
DOI
PubMed
高影响因子
CRYSTAL GROWTH & DESIGN
·
2025
·
IF 3.4
Zhijie Deng,Xinguo Ma,Youyou Guo,Changcun Han,Mian Jiang
Utilizing VO2 thermochromic materials to construct smart energy-saving windows is an arduous point in current science research. Herein, the polymer-assisted solution method prepared ultrathin Nb-doped VO2 films with diverse doping concentrations. Subsequently, an examination was carried out to investigate the crystal structure, and first-principles further explored the mechanism underlying the reduction of the phase transition temperature (Tc). The results suggest that the electronic doping and strain effects caused by adding Nb ions in the VO2 crystal lattice cause a decline in the phase transition temperature and a growth in the optical properties. Upon the amount of Nb doping attaining 6 atom %, the Tc of the VO2 films becomes 28.5 °C, approaching room temperature. Meanwhile, the maximum transmittance in the visible region (Tvis) is 70.1%, and the direct sunlight transmittance (Tsol) is 60.6%. The morphology test showed that the prepared films are well-crystallized. XPS spectral analysis reveals the relationship between the V-ion valence transition by doping Nb and the crystal phase transition. First-principles calculations show that the addition of Nb ions changes the original bond length of the crystal and triggers lattice distortion of intrinsic VO2. The band gap of monoclinic crystalline VO2 is lessened. The formation energies of the two crystallographic systems before doping are larger. The formation energy difference is reduced upon doping, and Tc is further reduced. These results are consistent with the experimental results. The high performance of the films illustrates their great possibilities for application in the domain of optical thin films.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Nano Energy
·
2025
·
IF 17.1
Weiguang Han,Xiaodong Zhang,Hui Li,Yang Fu,Boxiong Shen,Sheng-Qi Guo,Tianyi Ma
Activating the inherent piezoelectric effect of materials as an auxiliary driving force for photocatalytic performance is considered a reliable approach for developing a new generation of efficient photocatalytic systems, but research on modification strategies for optimizing piezoelectric performance is still in its infancy. In this work, we developed Nb-doped NaNbO 3 (N-NNO-4) piezoelectric based on self-doping strategy. Under the combined action of ultrasonic vibration and solar light irradiation, N-NNO-4 can generate high concentrations of hydroxyl radicals (•OH) in water environment, thereby achieving excellent oxidation performance. N-NNO-4 exhibits excellent piezo-photocatalytic performance in water pollution control applications. The reaction kinetic coefficients of its use as a piezo-photocatalyst for purifying common plasticizers dimethyl phthalate are 8.5 times and 6.8 times those of its use as a photocatalyst and piezocatalyst, respectively, and 17 times that of undoped NaNbO 3 (NNO) piezo-photocatalyst. Mechanism analysis shows that the excellent piezo-photocatalytic performance is not only attributable to the efficient charge separation efficiency induced by Nb-doped and the improved charge transfer ability, but also originate from the synergistic effect of band tilt caused by piezoelectric effect and efficient activation of interface H 2 O caused by Nb-doped. The synergistic effect opens up new channels for •OH generation and significantly intensifies the formation of •OH. The present study explores the feasibility of constructing an efficient piezoelectric photocatalytic system based on self-doping strategy, providing theoretical reference and experimental basis for utilizing green energy in nature to achieve sustainable environmental protection and development.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·Vol. 50
·期 9
·15172-15181
·
IF 5.1
Shan Gao,Peng Yang,Xinjian Li,Wenting Ji,Haidong Yu,Yaqi Chen,Yuewen Zhang,Hongan Ma,Xiaopeng Jia
SrTiO 3 (STO) is considered a promising high-temperature N-type thermoelectric material . However, its intrinsic insulating properties and high thermal conductivity limit the dimensionless quality factor (zT) due to its simple crystal structure and the existence of light elements. Along these lines, in this work, the optimization of the thermoelectric properties of STO-based materials was achieved by using the high temperature and high pressure (HPHT) method and adjusting the doping ratios of the La and Nb heavy elements . To enhance the doping effect, oxygen vacancies need to be formed within the sample. For this reason, titanium powder was added to the sample. Due to the confined environment induced by the high pressure, which can be attributed to the application of the HPHT method and the strong oxygen trapping ability of Ti at high temperatures, a reducing environment was attained for the samples, the latter, promoted the formation of oxygen vacancies in the synthesized samples, and semiconducting properties were achieved. The thermoelectric properties and microscopic morphology of the synthesized samples with different doping ratios of La and Nb were also thoroughly investigated. Finally, the maximum zT value obtained for the samples was 0.28@973 K. A fast, simple, and effective method for the preparation of oxygen-deficient packet-crystalline oxide materials was developed in this work, which paves the way for significantly improving their thermoelectric properties.
研究领域:
材料科学
·
热电学
·
陶瓷
·
固体物理
✓ 已验证
DOI
高影响因子
International Journal of Chemical Engineering
·
2017
·Vol. 2017
·期 1
·9136528
·
IF 0
Fei Chang,Rui Wang,Quan Zhou,Hu Pan,Heng Zhang
Mesoporous solid acids Ta 3 W 7 and Nb 3 W 7 were prepared from TaCl 5 and NbCl 5 with WCl 6 in the presence of stearic acid (SA) via a sol-gel method, respectively. For comparison, mesoporous Ta 3 W 7 -P123 mixed oxides and mesoporous Nb 3 W 7 -P123 mixed oxides were synthesized in the same way. The catalysts were characterized through TGA, XRD, SEM, TEM, BET, and NH 3 -TPD. Experimental results showed that Ta 3 W 7 -SA and Nb 3 W 7 -SA exhibited several advantages such as higher activity, shorter preparation period, lower cost, stronger acid sites, and higher surface area, which had potential to be used as mesoporous heterogeneous catalysts in biodiesel production.
研究领域:
材料化学
·
催化化学
·
能源化学
·
表面科学
·
多相催化
✓ 已验证
DOI
FUEL
·
2022
·
IF 8.035
Shuai Yang,Yifeng Chen,Haiwei Guo,Xunzhu Jiang,Jiawen Ma,Xinyang Li,Zhao Chen,Xiaodong Ma
The current catalysts for polychlorinated aromatics (PCAs) oxidation showed either poor low-temperature catalytic activity, low mineralization ability or bad stability, and developing oxygen vacancies enriched catalysts with abundant acid sites is a potential solution for the above drawbacks. Herein, oxygen vacancies enriched Nb-WO X were developed for o -DCB ( o -dichlorobenzene, a PCAs model compound) oxidation, and they showed notably better low-temperature catalytic activity with T 50% <350 °C than did commercial WO 3 (T 50% >400 °C) under the WHSV of 36000 mL g −1 h −1 . Nb-WO X supported Ru exhibited even lower T 50% (173 °C) and T 90% (238 °C), as well as high CO X yield with >99% ratio of CO 2 to CO and good stability (>99% conversion for 500 mins) when with 1.5 wt% Ru loading at 300 °C. The above phenomenon was attributed to the abundant oxygen vacancies and acid sites in Nb-WO X that contributed to the better redox property, stronger interaction with Ru species and the removal of accumulated chloride. The o -DCB oxidation mechanism revealed that the higher CO 2 ratio to CO on Ru/Nb-WO X arose from the deep oxidation of CO byproducts. The work described here will instruct us to degrade PCAs effectively through catalysts design.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
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
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY
·
2022
·Vol. 97
·期 7
·1695-1704
·
IF 3.709
Bao Guo,Jidong Liu,Shixiong Tang,Yida Liu,Zenan Tian,Jianhua Lv
BACKGROUND Whether waste polyethylene terephthalate (PET) can be effectively recycled is one of the main challenges of the current environmental problems. The hydrolysis of dimethyl terephthalate (DMT) to terephthalic acid (TPA) over Nb-modified HZSM-5 zeolite was studied. Nb/HZSM-5 zeolites with different loadings were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, NH 3 -temperature programmed desorption and pyridine adsorption infrared spectroscopy. The effects of different reaction conditions on the conversion of DMT and TPA yield were investigated. RESULTS The yield of TPA strongly depends on the reaction conditions and the loading of Nb. The niobium phase exists in the form of Nb 2 O 5 on the zeolite and interacts with the surface of HZSM-5 to produce the active site of Brønsted acid. The yield of TPA is closely related to the concentration of Brønsted acid sites. On 0.6Nb/HZSM-5 catalyst, the yield of TPA is highest, at about 94%. CONCLUSION Nb/HZSM-5 catalyst has excellent catalytic activity and high stability for DMT hydrolysis. In addition, the product TPA prepared in this study can be directly applied to the current PET production supply chain, providing a promising catalytic route. © 2022 Society of Chemical Industry (SCI).
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2019
·Vol. 34
·期 24
·4045-4055
·
IF 1.982
Bo-Qiong Li,Xin-Cheng Li,Xing Lu
In recent years, there has been a significant thrust toward the development of novel implant alloys based on β-Ti with low Young’s modulus to prevent stress shielding. In this study, porous Ti–Nb–Ta–Zr alloys with porosity of <55% and macro-pore size of 100–400 μm for biomedical applications were successfully fabricated by a space-holder method. The microstructure and compressive behavior were studied. The results show that the micro-pore size of porous Ti–Nb–Ta–Zr alloys decreases with an increase in the amount of the process control agent (PCA), which has no obvious effect on the porosity and the macro-pore size formed by the space holder. Porous Ti–Nb–Ta–Zr alloys fail mainly because of the cleavage and ductile fracture with some dimples in compression. The compressive modulus increases from 0.6 to 6.5 GPa with the increase in the PCA and decrease of the space holder. The influence mechanism has been analyzed by the finite element calculation and the Gibson–Ashby model.
研究领域:
材料科学
·
生物医学工程
✓ 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）