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51.
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Yanchen Liu Chenchen Wang Shuo Zhao Lin Zhang Kai Zhang Fujun Li Jun Chen 《Chemical science》2021,12(3):1062
Layered manganese-based oxides are promising candidates as cathode materials for sodium-ion batteries (SIBs) due to their low cost and high specific capacity. However, the Jahn–Teller distortion from high-spin Mn3+ induces detrimental lattice strain and severe structural degradation during sodiation and desodiation. Herein, lithium is introduced to partially substitute manganese ions to form distorted P′2-Na0.67Li0.05Mn0.95O2, which leads to restrained anisotropic change of Mn–O bond lengths and reinforced bond strength in the [MnO6] octahedra by mitigation of Jahn–Teller distortion and contraction of MnO2 layers. This ensures the structural stability during charge and discharge of P′2-Na0.67Li0.05Mn0.95O2 and Na+/vacancy disordering for facile Na+ diffusion in the Na layers with a low activation energy barrier of ∼0.53 eV. It exhibits a high specific capacity of 192.2 mA h g−1, good cycling stability (90.3% capacity retention after 100 cycles) and superior rate capability (118.5 mA h g−1 at 1.0 A g−1), as well as smooth charge/discharge profiles. This strategy is effective to tune the crystal structure of layered oxide cathodes for SIBs with high performance.Li-Substitution in P′2-Na0.67MnO2 mitigates the anisotropic change of Mn–O bonds and Na/vacancy ordering, and hence significantly promotes its cycling stability and rate capability as a cathode material for sodium-ion batteries. 相似文献
53.
Fe3+/V5+/TiO2复合纳米微粒光催化性能的研究 总被引:29,自引:1,他引:29
采用溶胶凝胶法制备了Fe^3 /V^5 /TiO2复合纳米微粒作为光催化剂。光降解反应结果表明,其掺杂催化剂Fe^3 /V^5 /TiO2的光催化活性明显提高。光电化学研究显示,铁离子可以成为电荷陷阱,促进空穴的界面传递反应。适量钒离子掺杂使TiO2电极的光电流升高,导带中电子浓度的增大,加快了界面的电子传递反应。共掺杂催化剂中,Fe^3 、V^5 分别提供了空穴与电子的陷阱,同时加快了电子与空穴的界面传递反应,从 更有效地提高光催化活性。双组份共掺杂为提高TiO2光催化活性提供新的途径。 相似文献
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HUA Guo-Pinga ZHU Xiao-Tongb ZHANG Jin-Pengb XU Jia-Ningb WANG Qianb JI Shun-Junc ZHANG Yongc TU Shu-Jiangb② a 《结构化学》2006,25(5):599-603
1 INTRODUCTION Various quinolone derivatives are known to dis- play interesting biological properties ranging from microbial activity to cytotoxicity[1]. They have been reported as antiviral (HIV-1)[2] and antitumor agents[3] as well as used as tubulin[4], topoisomerase[5] and thrombocyte inhibitors[6]. As a member of the quino- lone family, substituted N-phenyl-2-quinolones re-present the structural basis of many biologically active compounds, such as protein kinase inhibitors, immunodu… 相似文献
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华云 《数学的实践与认识》2012,42(13):218-221
给出了二阶导数属于Lp空间时Fejér和Hermite-Hadamard型不等式的推广,得到两个新结果. 相似文献
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ZHAO JinYu LI JiaHuang ZHANG Zheng ZHANG ShuYi QU Min FANG JianWen HUA ZiChun 《中国科学:物理学 力学 天文学(英文版)》2013,(7):1301-1309
The enthalpy and conformational volume changes in the photolyses of carboxy-hemoglobin (HbCO) of human, bovine, pig, horse and rabbit are investigated by photoacoustic calorimetry. Considering the time scales of the exciting laser pulse and the receiving ultrasound transducers (PVDF films and PZT ceramics), as well as the reaction lifetimes in the photolysis processes of HbCO, the measured results are related to the geminate recombination and tertiary relaxation in photolyses of HbCO. Moreover, the quantum yields of the five mammals are also measured by laser pump-probe technique. The results show that the dynamic parameters, such as enthalpy and conformational volume changes, differ between the processes of the geminate recombination and tertiary relaxation. Also, the dynamic parameters differ among the five mammals although some of them may be consistent with each other. 相似文献