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101.
Reduced Graphene‐Wrapped MnO2 Nanowires Self‐Inserted with Co3O4 Nanocages: Remarkable Enhanced Performances for Lithium‐Ion Anode Applications 下载免费PDF全文
Qi Zhu Yunhui Li Prof. Ying Gao Prof. Xiao Wang Prof. Shuyan Song 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6876-6880
A simple synthetic approach for graphene‐templated nanostructured MnO2 nanowires self‐inserted with Co3O4 nanocages is proposed in this work. The Co3O4 nanocages were penetrated in situ by MnO2 nanowires. As an anode, the as‐obtained MnO2–Co3O4–RGO composite exhibits remarkable enhanced performance compared with the MnO2–RGO and Co3O4–RGO samples. The MnO2–Co3O4–RGO electrode delivers a reversible capacity of up to 577.4 mA h g?1 after 400 cycles at 500 mA g?1 and the Coulombic efficiency of MnO2–Co3O4–RGO is about 96 %. 相似文献
102.
m‐Methoxy Substituents in a Tetraphenylethylene‐Based Hole‐Transport Material for Efficient Perovskite Solar Cells 下载免费PDF全文
Dr. Fei Wu Jianlin Liu Gang Wang Prof. Qunliang Song Dr. Linna Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(46):16636-16641
Three tetrapheynlethylene derivatives (N,N‐di(4‐methoxyphenyl)aminophenyl‐substituted tetraphenylethylene; TPE‐4DPA) with different methoxy positions (pp‐, pm‐, and po‐) have been synthesized and characterized. The methoxy groups can control the oxidation potential of the materials, and the electronic properties of the derivatives were affected by the position of the methoxy substituents. These compounds were synthesized in a facile and cost‐effective way, and were applied as hole‐transport materials in perovskite solar cells. The corresponding cell performances were compared with respect to their structure modifications, and it was found that the derivative with m‐OMe substituents showed the highest power conversion efficiency (PCE) of 15.4 %, with a Jsc value of 20.04 mA cm?2, a Voc value of 1.07 V, and a fill factor (FF) value of 0.72, which is higher than the p‐OMe and o‐OMe substituents. Moreover, the PCE of pm‐TPE‐4DPA is comparable with that of the state‐of‐the‐art 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene under identical conditions. 相似文献
103.
Structure, kinetics of crystallization, and dielectric resonances of waste-derived glass-ceramic prepared via quench-heating route were studied as a function of dosage of iron ore tailing (IOT) within 20–40 wt% using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and vector network analyzer (VNA) measurements. The glass-ceramic mainly consisted of ferrite crystals embedded in borosilicate glass matrix. Crystallization kinetics and morphologies of ferrite crystals as well as coordination transformation of boron between [BO4] and [BO3] in glass network were adjustable by changing the amount of IOT. Dielectric resonances in 6–13 GHz were found to be dominated by oscillations of Ca2+ cations in glass network with [SiO4] units on their neighboring sites. Ni2+ ions made a small contribution to those resonances. Diopside formed when IOT exceeded 35 wt%, which led to weakening of the resonances. 相似文献
104.
105.
Ao‐kai Zhang Jun Ling Kewen Li Guo‐dong Fu Tasuku Nakajima Takayuki Nonoyama Takayuki Kurokawa Jian Ping Gong 《Journal of Polymer Science.Polymer Physics》2016,54(13):1227-1236
In this study, controlled amount of dangling ends is introduced to the two series of poly(ethylene glycol)‐based hydrogel networks with three and four crosslinking functionality by using click chemistry. The structure of the gels with regulated defect percentage is confirmed by comparing the results of low‐field NMR characterization and Monte Carlo simulation. The mechanical properties of these gels were characterized by tensile stress–strain behaviors of the gels, and the results are analyzed by Gent model and Mooney–Rivlin model. The shear modulus of the swollen gels is found to be dependent on the functionality of the network, and decreases with the defect percentage. Furthermore, the value of shear modulus well obeys the Phantom model for all the gels with varied percentage of the defects. The maximum extension ratio, obtained from the fitting of Gent model, is also found to be dependent on the functionality of the network, and does not change with the defect percentage, except at very high defect percentage. The value of the maximum extension ratio is between that predicted from Phantom model and the Affine model. This indicates that at the large deformation, the fluctuation of the crosslinking points is suppressed for some extend but still exists. Polymer volume fractions at various defect percentages obtained from prediction of Flory–Rehner model are found to be in well agreement with the swelling experiment. All these results indicate that click chemistry is a powerful method to regulate the network structure and mechanical properties of the gels. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1227–1236 相似文献
106.
以偶氮二异丁腈、十二胺为主要原料,通过Pinner反应制备了一种两端各带有12个碳烷基链的水溶性偶氮引发剂——2,2'-偶氮二异丁基十二脒盐酸盐AIBL.采用核磁氢谱、元素分析及液相色谱对AIBL进行了结构及纯度表征,采用TGA、DSC和紫外分光光度计研究了其热分解现象和热分解动力学,采用表面张力仪对其表面活性进行了测定.结果表明,所合成的引发剂AIBL具有预想的结构和较高的纯度,其热分解反应属于一级反应,热分解活化能为134.80 k J/mol,70℃下水中的半衰期约为4 h;AIBL在水溶液中具有表面活性,其临界胶束浓度为0.13 g/L,对应的表面张力为33.57 m N/m.以丙烯酰胺为单体、AIBL为引发剂制备了水溶性端基疏水聚合物SPAM.采用溴化法研究其转化率,应用乌氏黏度法、零切黏度法以及荧光探针对其缔合作用进行了研究.结果表明,AIBL具有良好的引发丙烯酰胺聚合的能力;相对于不带疏水长链的引发剂所合成的聚合物PAM,SPAM具有明显的疏水缔合效应,这说明AIBL成功地将疏水长链引入到聚合物的端基中,从而形成端基疏水聚合物. 相似文献
107.
A study of the effect of step excrescences and free‐stream disturbances on boundary layer stability 下载免费PDF全文
In this work, a study of the mechanism by which free‐stream acoustic and vorticity disturbances interact with a boundary layer flow developing over a flat plate featuring a step excrescence located at a certain distance from a blunt leading edge is included. The numerical tool is a high‐fidelity implicit numerical algorithm solving for the unsteady, compressible form of the Navier–Stokes equations in a body‐fitted curvilinear coordinates and employing high‐accurate compact differencing schemes with Pade‐type filters. Acoustic and vorticity waves are generated using a source term in the momentum and energy equations, as opposed to using inflow boundary conditions, to avoid spurious waves that may propagate from boundaries. The results show that the receptivity to surface step excrescences is largely the result of an overall adverse pressure gradient posed by the step, and that the free‐stream disturbances accelerate the generation of instabilities in the downstream. As expected, it is found that the acoustic disturbance interacting with the surface imperfection is more efficient in exciting the Tollmien–Schlichting waves than the vorticity disturbance. The latter generates Tollmien–Schlichting waves that are grouped in wave packets consistent with the wavelength of the free‐stream disturbance. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
108.
Sorption of methanol,dimethyl carbonate,methyl acetate,and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis 下载免费PDF全文
Ondřej Vopička Kryštof Pilnáček Petr Číhal Karel Friess 《Journal of Polymer Science.Polymer Physics》2016,54(5):561-569
Sorption of vapors of four organic compounds in two glassy polymers, cellulose triacetate (CTA) and poly[(trimethylsilyl)propyne] (PTMSP), has been reported and analyzed in terms of Guggenheim‐Anderson‐De Boer (GAB) model. These two structurally and physicochemically different glassy polymers both independently showed that one sorption site was formed by about three monomeric units. This finding held true for vapors of all characterized compounds; that is, for methanol, for its derivatives dimethyl carbonate and methyl acetate, and for acetone. The “rule of three” might thus also be applicable to other sorbates and glassy polymers. Further, an original modification of the GAB model for the sorption of alcohols in PTMSP was derived and successfully tested. Overall, the analyses of the sorption isotherms, heats of sorption and diffusion coefficients supported the view that the sorption of vapors in glassy polymers has adsorptive nature. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 561–569 相似文献
109.
110.
In this paper, the nonlinear dynamics of a pipe imperfectly supported at the upstream end and free at the other and conveying fluid is investigated. The imperfect support is modelled via cubic translational and rotational springs. The equation of motion is obtained via Hamilton’s principle for an open system, and the Galerkin method is used for discretizing the resulting partial differential equation. The dynamics of a system with either strong rotational or strong translational stiffness is examined in details. Numerical results show that similarly to a cantilevered pipe, the system undergoes a supercritical Hopf bifurcation leading to period-1 limit cycle oscillations. The Hopf bifurcation may, however, occur at a much lower flow velocity compared to the perfect system. At higher flow velocities, quasi-periodic and chaotic-like motions may be observed. The amplitude of transverse displacement is generally much higher than that for a cantilevered pipe, mainly due to large-amplitude rigid-body motion. In addition, effects of the mass ratio, internal dissipation, hardening- or softening-type nonlinearity, as well as concentrated- or distributed-type nonlinearity on the dynamics of the system are examined. 相似文献