排序方式: 共有21条查询结果,搜索用时 25 毫秒
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Chunxiang Hu Yunyun He Shuiliang Chen Yongmei Zhu Muddasir Hanif Haoqing Hou 《Journal of Solid State Electrochemistry》2014,18(10):2797-2802
A binder-free activated carbon paper (ACP) was simply prepared for electric double-layer capacitors by the carbonization of filter paper, followed by heat-air activation at a lower temperature. The electrochemical cells assembled using the as-prepared ACP-470 provides a high specific capacitance of 296.4 F g?1 at current density of 0.5 A g?1 and a high rate performance at a current density of 150 A g?1 with a capacitance of 191.2 F g?1 and a high cycle ability at 10,000 recycles with 100 % capacitance retention. In addition, the ACP has a lower electrical resistivity and provides an effective energy storage performance with a maximum energy density of 41.2 Wh kg?1 and a maximum power density of 138.0 kW kg?1 in a voltage range of 1 V. 相似文献
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Liu L Qiu S Wang B Zhang W Lu P Xie Z Hanif M Ma Y Shen J 《The journal of physical chemistry. B》2005,109(49):23366-23370
We have investigated the thermal degradation in air by Fourier transform infrared spectroscopy of a ladder-type copolymer containing fluorene units in the backbone (Me-LPF), to reveal the formation of the ketonic defects. As thermal treatment of Me-LPF film at 200 degrees C in air proceeds, a new group of complex absorption bands due to degradation products arises in the range between 1800 and 1600 cm(-1). The observed overlapping bands were separated and assigned by utilizing the second-derivative IR spectral analysis, which can narrow the peak width to one-third of the originals and thereby eases the analysis. The degraded products were assigned as fluorenone (1718 cm(-1)) and benzophenone (Ar-(C=O)-Ar) (1665 cm(-1)), formed by the oxidation of the backbone, and acylphenone (Ar-(C=O)-R) (1685 cm(-1)) from the side chain. The fluorenone was found to be the major component among the degraded products in the main chain, and the time and temperature dependence indicated that the oxidation is a kind of autocatalytic radical-chain process. The oxidation can reach a very high degree (approximately 30% for 6 h oxidation at 240 degrees C estimated by absorption of the alkyl). Our results suggest the possibility of the oxidation of the 9-bialkylfluorene sites. We propose that the degradation of the alkyl in the side chain can help the radicals to propagate in the chain reaction. 相似文献
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Bing Yang Dr. Soo‐Kang Kim Hai Xu Young‐Il Park Houyu Zhang Dr. Cheng Gu Fangzhong Shen Dr. Chunlei Wang Dandan Liu Xiaodong Liu Prof. Muddasir Hanif Shi Tang Weijun Li Feng Li Dr. Jiacong Shen Prof. Jong‐Wook Park Prof. Yuguang Ma Prof. 《Chemphyschem》2008,9(17):2601-2609
Herein, we describe the molecular electronic structure, optical, and charge‐transport properties of anthracene derivatives computationally using density functional theory to understand the factors responsible for the improved efficiency and stability of organic light‐emitting diodes (OLEDs) with triphenylamine (TPA)‐substituted anthracene derivatives. The high performance of OLEDs with TPA‐substituted anthracene is revealed to derive from three original features in comparison with aryl‐substituted anthracene derivatives: 1) the HOMO and LUMO are localized separately on TPA and anthracene moieties, respectively, which leads to better stability of the OLEDs due to the more stable cation of TPA under a hole majority‐carrier environment; 2) the more balanceable hole and electron transport together with the easier hole injection leads to a larger rate of hole–electron recombination, which corresponds to the higher electroluminescence efficiency; and 3) the increasing reorganization energy for both hole and electron transport and the higher HOMO energy level provide a stable potential well for hole trapping, and then trapped holes induce a built‐in electric field to prompt the balance of charge‐carrier injection. 相似文献
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Muhammad Haji Hanif Muddasir Tahiri Iftikhar Ahmad Versiani Muhammad Ali Shah Faheem Khaliq Obaid Ali Syed Tahir Ahmed Safeer 《Research on Chemical Intermediates》2018,44(10):6387-6400
Research on Chemical Intermediates - Among the reactive oxygen species, the superoxide anion radical (O 2 ·? ) has a fundamental role in several biological functions. Consequently, its... 相似文献
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Bing Yang Zengqi Xie Houyu Zhang Hai Xu Muddasir Hanif Xin Gu Feng He Jingsheng Yu Yuguang Ma Jiacong Shen Xiaodong Liu Jikang Feng 《Chemical physics》2008
2,5-Diphenyl-1,4-distyrylbenzene (DPDSB), a model compound of PPV, have been synthesized with two isomers: cis- and trans-DPDSB in our lab. We have found three distinguishing features of photophysical properties between these two isomers. To explain these three special spectral behaviors, the quantum-chemical computations were performed to investigate the ground-state and excited-state molecular geometries, electronic structure, absorption and emission properties, potential–energy curve of the ground-state and excited-state, and so on. According to our calculated results, the nature causing above distinguishing photophysical properties is larger configuration displacement of cis-DPDSB than trans-DPDSB from the ground-state to the excited-state, especially for the changes in torsion angle along vinyl double bonds in cis-DPDSB. 相似文献
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Li M Tang S Shen F Liu M Xie W Xia H Liu L Tian L Xie Z Lu P Hanif M Lu D Cheng G Ma Y 《The journal of physical chemistry. B》2006,110(36):17784-17789
The electropolymerization behaviors of an electroactive and luminescent compound TCPC as precursor are studied. The resultant electrochemical deposition (ED) films are characterized by cyclic voltammetry (CV), UV-vis, fluorescence spectra, scanning electron microscopy (SEM), and atomic force microscopy (AFM). Under the CV mode with potential range of -0.5 to 0.85 V vs Ag/Ag(+), the coupling reactions between the carbazole units of TCPC are very efficient, while the fluorescent trifluorene segment in TCPC is chemically inert in this potential range, which results in a highly fluorescent film formation on indium tin oxide (ITO) electrode. The deposition parameters for preparing the TCPC-based ED films are optimized, and the best ED film gives the fluorescence efficiency of 45.5% with surface roughness of 2.8 nm and morphologic stability as heating to 180 degrees C. The light-emitting devices (LEDs) using this ED film as light emitting layer with structure ITO/ED film (approximately 100 nm)/Ba/Al achieve maximum luminescence and external quantum efficiency of 4224 cd/m(2) at 17 V and 0.72% at 11.5 V, respectively, which are better than the device using TCPC spin-coating films as emitting layer. The technique provides a facile route toward a patternable luminescent film and device because such luminescent ED films can be manipulatively deposited on the electrified electrode. 相似文献