CERAMICS INTERNATIONAL
·
2017
·Vol. 44
·期 2
·1731-1736
·
IF 2.986
Jingbo Yu,Qian Zhang,Yi Gu,Anxian Lu
In this study, phosphate glasses embedded with Fe 2 O 3 quantum dots were prepared via a conventional melt quenching technology with further heat treatment. The effect of Fe 2 O 3 content on the structural, optical and magneto-optical properties was investigated. The results showed that the addition of Fe 2 O 3 had no obvious influence on the structure units that built up the host glass and the amorphous nature of glass. In the glass matrix , the existence of Fe 2 O 3 quantum dots was confirmed by high resolution transmission electron microscope . Meanwhile, optical study clearly demonstrated a red shift in optical cut-off wavelength resulted from the size quantization effect. The highest Verdet constant (22.33°/T-cm) was measured for the glass containing 1 mol% Fe 2 O 3 , which was ~ 7 times higher than that of the glass matrix. As the increment of Fe 2 O 3 contents, a phase evolution of Fe 2 O 3 quantum dots from amorphous phase to γ-Fe 2 O 3 phase was recorded due to the Ostwald Ripening effect. Interestingly, a concentration quenching phenomenon in Verdet constant was observed along with the phase evolution of Fe 2 O 3 quantum dots. When the content of Fe 2 O 3 is up to 2 mol%, the glass exhibited paramagnetism with the Verdet constant of − 2.833°/T-cm. This finding can provide a new idea for the development of quantum dot embedded magneto-optical glass.
研究领域:
材料科学
·
磁光材料
·
纳米材料
·
无机非金属材料
·
光学玻璃
·
凝聚态物理
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·Vol. 46
·期 16
·25802-25807
·
IF 3.83
Jun Xiao,Yan Jia,Dongqing Liu,Haifeng Cheng
Manufacturing complexity and poor machinability hinder the preparation of complex-shaped ceramic composites. Three-dimensional printing can overcome this difficulty. Herein, we report a type of photocurable preceramic resin containing SiO 2 nanoparticles (up to 20 wt% of polymer), which do not affect the photocurability of the preceramic resin, and a small amount of SiC nanofibres (1 wt%). We successfully printed precise green bodies with a complex shape by digital light processing and converted them into ceramic composites via pyrolysis at 1300 °C under a N 2 atmosphere. The introduction of SiO 2 and SiC into the ceramic composites led to reduced weight loss of the composites during pyrolysis and a decrease in their porosity and enhancement in their mechanical properties after pyrolysis. The properties of the printed samples pyrolysed at different ramping rates were compared, and the effects of the microstructure on the mechanical properties of the composites were investigated.
研究领域:
材料科学
·
陶瓷工程
·
增材制造
·
高分子转化陶瓷
·
复合材料
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2014
·Vol. 39
·期 28
·16123-16131
·
IF 2.93
Yufei Wang,Shuanjin Wang,Min Xiao,Shuqin Song,Dongmei Han,Michael A. Hickner,Yuezhong Meng
Novel sulfonated poly (fluorenyl ether ketone) with pendant quaternary ammonium groups (SPFEKA) was successfully synthesized by one-pot copolymerization of bis(4-fluoro-3-sulfophenyl)sulfone disodium salt, 4,4′-difluorobenzophenone, bisphenol fluorene and 2,2′-dimethylaminemethylene-9,9′-bis(4-hydroxyphenyl) fluorene (DABPF). The chemical structures were confirmed by FT-IR, and 1 H NMR. The thermal properties were fully investigated by TGA . The synthesized copolymers SPFEKAs are soluble in aprotic solvents, and can be cast into membranes on a glass plate from their N,N′-dimethylacetamide (DMAc) solution. A new kind of amphoteric ion exchange membrane (AIEM) was obtained by immersed SPFEKA into 1 M sulfuric acid. The proton conductivities of these membranes are comparable to the most reported sulfonated polymers under the same conditions. The permeability of vanadium ions in vanadium redox flow battery (VRB) was effectively suppressed by introducing quaternary ammonium groups for Donnan exclusion effect . AIEM-20% possess a only 4.4% vanadium ion permeability of Nafion 115. Cell performance tests showed that the VRB assembled with AIEM-20% shows the highest coulombic efficiency (CE) at the current density of 50 mA/cm 2 , because of its lowest VO 2+ permeability. In conclusion, these ionomers could be promising candidates for ion-exchange membranes for VRB applications.
研究领域:
材料科学
·
电化学
·
能源存储
·
高分子化学
·
膜科学
✓ 已验证
DOI
高影响因子
TETRAHEDRON
·
2019
·Vol. 75
·期 31
·4174-4179
·
IF 2.379
Yingying Zuo,Feng Xiong,Jing Zhao
Organic sulfur compounds have broad applications in biology, medicine and material sciences and intensive efforts have been devoted to developing mild and general C–S bond-forming methods. However, a mild, transition-metal-free, direct C–H bond functionalization method remains elusive. Here, we report the use of an internal oxidant-directing strategy to achieve this goal. The cascade reactions described here show excellent chemoselectivity and a wide substrate scope for both oxyamines and sulfenylation reagents. This study enlarges the synthesis toolbox for preparing structurally diverse sulfilimines under mild conditions.
研究领域:
有机化学
·
合成化学
·
药物化学
·
生物医学材料
·
分子生物学
✓ 已验证
DOI
高影响因子
RUSSIAN JOURNAL OF GENERAL CHEMISTRY
·
2021
·Vol. 91
·期 4
·726-731
·
IF 0.868
Xu Y.,Hu Y.,Bao Q.,Zhang J.,Liu B.,Zhang Z.,Zhang Q.,Zhang H.
Copper phyllosilicate has been synthesized from a solution of sodium silicate and copper nitrate by co-precipitation under acidic conditions followed by reduction under H 2 flow for using it as the Cu/SiO 2 catalyst. The catalyst has been characterized by XRD, XPS, FTIR and Raman spectra, EDS, BET, and TEM. It is confirmed that only copper phyllosilicate and SiO 2 exist in the catalyst precursor, and there has been no CuO. Physical and chemical properties of Cu/SiO 2 catalyst have been evaluated. The Cu/SiO 2 catalyst has not only a large specific surface area and abundant mesopores but also the advantages of high dispersion of copper nanoparticles and the combination of Cu 0 and Cu + . The catalyst demonstrates high activity and selectivity in the reaction of 2-butanol dehydrogenation to methyl ethyl ketone.
研究领域:
催化化学
·
材料科学
·
物理化学
·
纳米材料
·
有机合成
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 28
·14162-14170
·
IF 11.301
Zhihong Du,Keyun Li,Hailei Zhao,Xu Dong,Yang Zhang,Konrad Świerczek
Modified by Sm0.2Ce0.8O2−δ (SDC) nanoparticles (NPs), SmBaCo2O5+δ (SBCO) double perovskite oxide is evaluated as a promising cathode material for intermediate temperature solid oxide fuel cells. The SDC NPs are epitaxially grown on the surface of SBCO with (220) planes of SDC aligning smoothly to (020) or (100) planes of SBCO, forming a tight, coherent connection at the interface. The influence of this modification on thermal expansion, oxygen diffusion, electrical conductivity and electrochemical properties is investigated thoroughly in this work. The designed SBCO–SDC cathode material demonstrates a lower thermal expansion coefficient (TEC), ∼16.4 × 10−6 K−1, than that of the unmodified SBCO, ∼20.9 × 10−6 K−1. While SDC coating results in a decreased total electrical conductivity, it facilitates oxygen bulk diffusion and improves the surface exchange reaction kinetics. Coating with SDC NPs can accelerate the rate-determining process of dissociation of the absorbed molecular oxygen, especially at intermediate temperatures. Accordingly, the constructed symmetrical cell with the La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) electrolyte shows lower polarization resistance values, if the SBCO–SDC cathode is utilized. Also, the LSGM electrolyte-supported (300 μm) full cell is found to deliver a high power density of 800 mW cm−2 at 800 °C. Owing to the strong and coherent interfacial connection, the developed cathode demonstrates a relatively steady electrochemical performance.
研究领域:
材料科学
·
能源化学
·
电化学
·
无机功能材料
·
燃料电池技术
✓ 已验证
DOI
高影响因子
Science China-Materials
·
2016
·Vol. 59
·期 10
·833-841
·
IF 0
Shen Ting,Tian Jianjun,Li Bo,Cao Guozhong
TiO 2 nanocrystals are widely used in photoanodes for quantum dot solar cells (QDSCs) owing to their chemical stability and suitable energy band structure. However, surface defects and grain boundaries of TiO 2 nanocrystals photoanodes allow high surface charge recombination, which limits the performance of QDSCs. In this work, an ultrathin TiO 2 layer is introduced to the surface of TiO 2 photoanodes by atomic layer deposition (ALD). The ultrathin layer not only reduces the surface defects of TiO 2 nanoparticles and strengthens the connection between adjacent nanoparticles to suppress the charge recombination for improving the electron collection efficiency (η cc ), but also increases the surface energy of photoanodes to load more quantum dots (QDs) for enhancing the light harvesting efficiency (LHE). As a result, the solar cell based on CdS/CdSe QDs with ALD treatment exhibits an efficiency of 5.07% that is much higher than that of the cells without modification (4.03%).
研究领域:
材料科学
·
纳米科技
·
能源化学
·
光伏技术
·
表面工程
·
半导体物理
·
光电转换
✓ 已验证
DOI
COMPOSITES PART B-ENGINEERING
·
2019
·
IF 6.864
Chao Liu,Yufei Dong,Yang Lin,Hongxia Yan,Wenbo Zhang,Yan Bao,Jianzhong Ma
In order to simultaneously improve the dispersibility of graphene in the bismaleimide (BMI) resin and the interfacial interaction between them, the polytriazine@RGO nanocomposite (PTZ@RGO) with terminal amine was obtained by the method of one-step precipitation polymerization. The PTZ@RGO hybrid nanocomposite was then chosen as filler to improve the mechanical and tribological properties of BMI resin. Through effective surface modification, the compatibility and interface strength between graphene and BMI matrix were significantly improved, leading to the flexural strength , impact strength , anti-friction, wear resistance and thermal stability of PTZ@RGO/BMI composites were significantly improved as compared to those of neat BMI resin and RGO/BMI composites. The other properties including hardness and thermal properties of composites were all improved with increasing amount of PTZ@RGO fillers. These high performance BMI composites have a great potential for application in aerospace, mechanical engineering and other automobile brake devices.
研究领域:
材料科学
·
高分子复合材料
·
表面工程
·
摩擦学
·
航空航天材料
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
·
2021
·
IF 4.185
Jizhen Zhu,Sixu Wang,Mohsin Raza,Yuan Feng,Jing Li,Yebing Mao,Liang Yu,Yong Qian,Xingcai Lu
Methanol is an attractive oxygenate increasingly used as primary fuel for dual-fuel combustion technology yielding beneficial thermal-efficiency and emissions in modern engines. As such, it is significant to fundamentally understand the autoignition behavior of methanol/diesel mixtures. This study measured the ignition delay times (IDTs) of methanol/diesel blends with different mixing ratios (30%, 50%, 70% methanol by mol.) on a heated shock tube and a heated rapid compression machine at temperatures of 650−1450 K, pressures of 6−20 bar, and equivalence ratios of 0.5, 1.0 and 2.0. The typical two-stage ignition characteristics with the negative temperature coefficient response were observed for dual-fuel mixtures. In general, both the total and first-stage IDTs decrease with the increment of pressure and equivalence ratio as well as diesel proportion in mixtures. The simulation results performed with a published detailed mechanism in conjunction with a tri-component diesel surrogate demonstrate generally good agreement with the experimental data at all test conditions. Moreover, a crossover of IDTs occurs at a higher temperature (~1500 K) for varying equivalence ratios, and experiment and simulation both exhibit a non-linear mixing effect of methanol addition on diesel ignition. Interestingly, simulation results clearly suggest a crossover (~940 K) for mixtures with varying methanol content at an intermediate-temperature, where the IDT of the mixture with a lower methanol ratio becomes longer as the temperature is higher than that of the crossover. Furthermore, brute-force sensitivity analyses assisted with reaction path analysis were conducted to gain deeper insights into the autoignition chemistry of dual-fuel mixtures, especially for the chemical interaction between both fuels during the low-temperature oxidation process . It is found that methanol hardly generates •OH, whereas •OH is mainly produced by the low-temperature reaction pathways of diesel. Thus, •OH is the bridge for both fuels during the ignition process. At the high methanol ratio, the H-abstraction of diesel is mainly via •HO 2 while CH 3 OH consumes a large percentage of •OH. Consequently, the competition between methanol and diesel for •OH radicals inhibits the overall reactivity of reaction network. In addition, the original data reported here lay a foundation for the development and validation of more accurate and robust dual-fuel kinetic schemes.
研究领域:
燃烧化学
·
燃料科学
·
化学动力学
·
内燃机工程
·
替代燃料技术
✓ 已验证
DOI
高影响因子
IONICS
·
2016
·Vol. 22
·期 11
·2225-2233
·
IF 2.119
Lu Juanjuan,Liu Yuelin,Liu Xinhe,Lu Xiaoquan,Liu Xiuhui
In this article, we constructed an electrochemical sensor for highly sensitive determination of β-nicotinamide adenine dinucleotide (NADH) using the poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide nanocomposite modified electrode (PDDA-rGO/GCE). The nanocomposite was characterized by transmission electron microscopy, Fourier transform-infrared spectrometry, ultraviolet-visible absorption spectrometry, cyclic voltammetry, and electrochemical impedance spectroscopy. The experimental results demonstrated that the fabricated sensor exhibited excellent electrocatalytic activity on the oxidation of NADH with a decreased about 200 mV in overpotential and 5.0-fold increment in the oxidation peak current compared to a bare GCE. Applying cyclic voltammetry, a wide linear range from 1.0 × 10 −7 to 2.9 × 10 −3 M with low limit of detection (LOD) of 3.4 × 10 −8 M and high sensitivity of 463.3 μA mM −1 cm −2 were obtained, which was superior to other NADH electrochemical sensors reported previously. Furthermore, the fabricated NADH sensor possessed excellent selectivity, reproducibility, and stability. The oxidation mechanism of NADH at the PDDA-rGO/GCE was also discussed in detail.
A simple NADH sensing platform based on PDDA-rGO composite is constructed, which exhibits an ultra-low detection limit ( 3.4×10-8 M) towards the oxidation of NADH, and the electrochemical reaction mechanism of NADH is discussed in detail.
研究领域:
生物电化学
·
生物传感器
·
纳米生物技术
·
分子诊断
·
转化医学
·
电分析化学
✓ 已验证
DOI
高影响因子
Small
·
2024
·Vol. 20
·期 29
·2310092
·
IF 13
Yu-Ren Xue,Chang Liu,Hao-Cheng Yang,Hong-Qing Liang,Chao Zhang,Zhi-Kang Xu
Supported ionic liquid membranes (SILMs), owing to their capacities in harnessing physicochemical properties of ionic liquid for exceptional CO 2 solubility, have emerged as a promising platform for CO 2 extraction. Despite great achievements, existing SILMs suffer from poor structural and performance stability under high-pressure or long-term operations, significantly limiting their applications. Herein, a one-step and in situ interfacial polymerization strategy is proposed to elaborate a thin, mechanically-robust, and highly-permeable polyamide armor on the SILMs to effectively protect ionic liquid within porous supports, allowing for intensifying the overall stability of SILMs without compromising CO 2 separation performance. The armored SILMs have a profound increase of breakthrough pressure by 105% compared to conventional counterparts without armor, and display high and stable operating pressure exceeding that of most SILMs previously reported. It is further demonstrated that the armored SILMs exhibit ultrahigh ideal CO 2 /N 2 selectivity of about 200 and excellent CO 2 permeation of 78 barrers upon over 150 h operation, as opposed to the full failure of CO 2 separation performance within 36 h using conventional SILMs. The design concept of armor provides a flexible and additional dimension in developing high-performance and durable SILMs, pushing the practical application of ionic liquids in separation processes.
研究领域:
膜科学与技术
·
气体分离
·
环境化学
·
材料化学
·
化学工程
·
可持续能源技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2019
·Vol. 7
·期 37
·21378-21385
·
IF 10.733
Wei Wen,Jincheng Yao,Hua Tan,Jin-Ming Wu
Electrode materials with hollow micro/nanostructures and high electrical conductivity are important for achieving high-power supercapacitors, especially those with super-fast charging/discharging. TiN, which can be easily obtained from TiO2, is regarded as a high-power supercapacitor material. Here, we report that a nanoscale Kirkendall effect is triggered by surface branches on TiO2 nanowires, which then transform into hollow TiN nanotrees during a thermal nitridation process. The surface branches play a key role in accelerating the initial reaction, which forms a uniform, continuous surface TiN layer and induces the Kirkendall effect via surface diffusion. The hollow TiN nanotrees have a high surface area, porous structure, and high electrical conductivity. The constructed symmetric supercapacitors exhibit high areal and volumetric energy density, super-fast charge/discharge ability, and good capacitance retention up to 350 000 cycles. This work provides a new method to synthesize hollow TiN nanostructures and demonstrates their advantages in achieving high-power energy storage devices.
研究领域:
材料科学
·
纳米科技
·
电化学
·
能源存储
·
功能材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）