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921.
High‐Loading Nano‐SnO2 Encapsulated in situ in Three‐Dimensional Rigid Porous Carbon for Superior Lithium‐Ion Batteries 下载免费PDF全文
Hairong Xue Dr. Jianqing Zhao Jing Tang Hao Gong Prof. Ping He Prof. Haoshen Zhou Prof. Yusuke Yamauchi Prof. Jianping He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4915-4923
Tin oxide nanoparticles (SnO2 NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m2 g?1), and the SnO2 NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO2@OMC composite material can deliver an initial charge capacity of 943 mAh g?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g?1, even exhibit a capacity of 503 mA h g?1 after 100 cycles at 160 mA g?1. In situ encapsulation of the SnO2 NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO2 particles (SnO2/OMC). The significantly improved electrochemical performance of the SnO2@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO2 NPs. 相似文献
922.
923.
Jinhua Ji Hao Liu Zewei Chen Yajun Fu Prof. Weijun Yang Prof. Shuang-Feng Yin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(43):11102-11109
Metal-organic framework (MOF) is an ideal precursor/template for porous carbon, and its active components are uniformly doped, which can be used in energy storage and catalytic conversion fields. Metal-organic framework PCN-224 with carboxylporphyrin as the ligand was synthesized, and then Zn2+ and Co2+ ions were coordinated in the center of the porphyrin ring by post-modification. Here, PCN-224−ZnCo with different ratios of bimetallic Zn2+/Co2+ ions were used as the precursor, and the metal-nitrogen-carbon(M−N−C) material of PCN-224−ZnCo-950 was obtained by pyrolyzing the precursor at 950 °C in Ar. Because Zn is easy to volatilize at 950 °C, the formed M−N−C materials can reflect different Co contents and different basic site concentrations. The formed material still maintains the original basic framework. With the increase of Zn2+/Co2+ ratio in precursor, the concentration of N-containing alkaline sites in pyrolysis products gradually increase. Compared with the precursor, PCN-224−ZnCo1-950 with Zn2+/Co2+=1 : 1 has greatly improved basicity and suitable acidic/ alkaline site concentration. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO2 with epoxide. More importantly, the current method of adjusting the acidic/basic sites in M−N−C materials through volatilization of volatile metals can provide an effective strategy for adjusting the catalysis of MOF derivatives with porphyrin structure. 相似文献
924.
925.
Aimin Hao Xiaocui Yang Chunxiao Gao Yonghao Han Yongjun Tian 《Journal of Physics and Chemistry of Solids》2009,70(2):433-438
A theoretical investigation on the structural stabilities and electronic properties of HgTe under high pressure was conducted using first principles based on density functional theory. Our results demonstrate that the sequence of the pressure-induced phase transitions of HgTe is from the zinc blende, to cinnabar, rocksalt, orthorhombic, and CsCl-type structures. The pressure effects on the optical properties were discussed and compared with previous calculations and experimental data whenever available. 相似文献
926.
In this paper, we investigate the convergence of the proximal iteratively reweighted algorithm for a class of nonconvex and nonsmooth problems. Such problems actually include numerous models in the area of signal processing and machine learning research. Two extensions of the algorithm are also studied. We provide a unified scheme for these three algorithms. With the Kurdyka–?ojasiewicz property, we prove that the unified algorithm globally converges to a critical point of the objective function. 相似文献
927.
Back Cover: Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite (Chem. Eur. J. 21/2016) 下载免费PDF全文
928.
Shen Honglong Yang Xiaoqiang Song Juanjuan Gao Haiwen Wu Zongdeng Yu Jia Lei Wu Yang Jiazhi He Guangyu Hao Qingli 《Journal of Solid State Electrochemistry》2022,26(2):353-363
Journal of Solid State Electrochemistry - Long-cycle stability and high-energy density are big challenges for developing high-performance hybrid supercapacitor (HSC) electrode materials. In this... 相似文献
929.
Fine tuning the assembly and gel behaviors of PEGylated polypeptide conjugates by the copolymerization of l‐alanine and γ‐benzyl‐l‐glutamate N‐carboxyanhydrides 下载免费PDF全文
Yumin Zhang Huijuan Song Hao Zhang Pingsheng Huang Jinjian Liu Liping Chu Jianfeng Liu Weiwei Wang Zhen Cheng Deling Kong 《Journal of polymer science. Part A, Polymer chemistry》2017,55(9):1512-1523
Tuning the secondary structure of polypeptide is an effective strategy to modulate the assembly behaviors of polypeptide‐based copolymers. In this study, ring‐opening polymerization of l ‐alanine (Ala) and γ‐benzyl‐l ‐glutamate (BLG) N‐carboxyanhydrides was adopted using mPEG‐NH2 as the initiator to prepare mPEG‐poly(l ‐alanine‐co‐γ‐benzyl‐l ‐glutamate) (PEAB) copolymers with various Ala to BLG ratios. 1H NMR spectra and GPC test confirmed their well‐defined chemical structures. FT‐IR spectra indicated that at the powder state, all copolymers adopted both β‐sheet and α‐helical conformations. With the content of PBLG increased, the crystallization temperature and melting points of PEAB copolymers first rose then fell indicated by DSC curves. The self‐assembly of PEAB copolymers in dilute aqueous solution studied by DLS, TEM and circular dichroism spectra showed that PEAB copolymers self‐assembled into nanostructures with diverse morphologies and sizes due to distinct polypeptide conformations. Rheological analysis indicated that the alteration of the polypeptide composition can effectively modulate the modulus of PEAB assemblies in concentrated solutions. In all, copolymerization of two hydrophobic amino acid N‐carboxyanhydrides into the polypeptide block maybe an effective approach for modulating the assembly properties of PEGylated polypeptide. Besides, nanosilver‐encapsulated PEA or PEAB hydrogel showed promising antibacterial effect against Staphylococcus aureus and Bacillus subtillis. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1512–1523 相似文献
930.