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排序方式: 共有1612条查询结果,搜索用时 15 毫秒
951.
Lei Zhang Chengrui Wang Yuhai Dou Ningyan Cheng Dandan Cui Yi Du Porun Liu Mohammad Al‐Mamun Shanqing Zhang Huijun Zhao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8916-8920
The poor cycling stability resulting from the large volume expansion caused by lithiation is a critical issue for Si‐based anodes. Herein, we report for the first time of a new yolk–shell structured high tap density composite made of a carbon‐coated rigid SiO2 outer shell to confine multiple Si NPs (yolks) and carbon nanotubes (CNTs) with embedded Fe2O3 nanoparticles (NPs). The high tap density achieved and superior conductivity can be attributed to the efficiently utilised inner void containing multiple Si yolks, Fe2O3 NPs, and CNTs Li+ storage materials, and the bridged spaces between the inner Si yolks and outer shell through a conductive CNTs “highway”. Half cells can achieve a high area capacity of 3.6 mAh cm?2 and 95 % reversible capacity retention after 450 cycles. The full cell constructed using a Li‐rich Li2V2O5 cathode can achieve a high reversible capacity of 260 mAh g?1 after 300 cycles. 相似文献
952.
Chen SW Zhang YL Dou W Wang YW Liu WS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):826-830
Four ligands 1,10-phenanthroline-5,6-bis(N,N-dibenzyl-1′-oxopropylamide) (La) 1,10-phenanthroline-5,6-bis(N-methyl-N-benzyl-1′-oxopropylamide) (Lb) 1,10-phenanthroline-5,6-bis(N-benzyl-1′-oxopropylamide) (Lc) and 1,10-phenanthroline-5,6-bis(N,N-diethyl-1′-oxopropylamide) (Ld), and their lanthanide(III) (La and Eu) complexes were synthesized. The complexes were characterized by elemental analysis, IR, fluorescence spectroscopy and conductivity. The lanthanide atoms are coordinated by O atoms from C=O, Ar–O –C and N atoms from phen With the difference of the ligands, the fluorescent intensities of the Eu(III) complexes vary regularly in the THF solution. Some factors that influence the fluorescent intensity were discussed. 相似文献
953.
Ning Li Lu Liu Kun Wang Prof. Jin Niu Prof. Zhengping Zhang Prof. Meiling Dou Prof. Feng Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(42):10987-10997
Exploring high-performance non-precious-metal electrocatalysts for the oxygen reduction reaction (ORR) is critical. Herein, a scalable and cost-effective strategy is reported for the construction of one-dimensional carbon nanofiber architectures with simultaneous decoration of single Fe−Nx sites and highly dispersed Fe/Fe3C nanoparticles for efficient ORR, through the FeIII-complex-assisted electrospinning of gelatin nanofibers with subsequent pre-oxidation and carbonization. Results show that the presence of a FeIII complex enables the 1D gelatin nanofibers to be well retained during the pre-oxidation process. Owing to the distinct 1D nanofiber structure and the synergistic effect of Fe/Fe3C and Fe−Nx sites, the resulting electrocatalyst is highly active for ORR with a half-wave potential of 0.885 V (outperforming commercial Pt/C) and a superior electrochemical stability in alkaline electrolytes. Similarly, it also shows a high power density (144.7 mW cm−2) and a superior stability in Zn-air batteries. This work opens a path for the design and synthesis of 1D carbon electrocatalyst for efficient ORR catalysis. 相似文献
954.
955.
956.
An efficient synthesis of trisubstituted alkenes including 1,2-heterodisubstituted alkenes has been described. Reactions of thiols and amines with 1,1-dibromo-1-alkenes in the presence of TBAF·3H(2)O afford (Z)-2-bromovinyl sulfides and (Z)-2-bromovinyl amines regio- and stereoselectively. The reaction proceeds under catalyst-free conditions with high efficiency. The coupling reactions of the obtained products bearing bromine atoms with phenylacetylene and phenylboronic acid gave trisubstituted alkenes in good to excellent yields. Cross-coupling with various N, O, S, and P nucleophiles selectively generated 1,2-N,O, 1,2-N,S, 1,2-S,P, 1,2-S,S, and 1,2-S,O heterodisubstituted alkenes. 相似文献
957.
Chengjuan Li Suna Wang Xianxi Zhang Jianmin Dou Dacheng Li 《Journal of solid state chemistry》2011,184(7):1581-1590
Six complexes based on a flexible tripodal ligand H3TTTA (2,2′,2″-[1,3,5-triazine-2,4,6-triyltris(thio)]tris-acetic acid) have been hydrothermally synthesized and structurally characterized. X-ray single-crystal diffractions reveal that they have rich structural chemistry: mononuclear, [Zn(HTTTA)(2,2′-bpy)(H2O)3]n (1); dimeric metallamacrocycle, [Zn(HTTTA)(2,2′-bipy)(H2O)]n (2) and [Cd(HTTTA)(2,2′-bipy)(H2O)·H2O]n (3); two-dimensional networks with binodal (3,6)-connected CdI2 topology based on linear trinuclear M3(μ2-CO2)4(μ2-CO2)2 SBUs (Secondary Building Units), [M3(TTTA)2(2,2′-bipy)2(H2O)m·nH2O]n (M=Zn·4, m=0, n=4; Cd·5 and Mn·6, m=2; n=2). The value of pH and the metal ions has large influences on the resulting structures. The flexible tricarboxylic acid exhibits four coordination modes from monodentate to μ6-bridge. Fluorescence and magnetic properties of the complexes have also been investigated in details. 相似文献
958.
Dou L Gao J Richard E You J Chen CC Cha KC He Y Li G Yang Y 《Journal of the American Chemical Society》2012,134(24):10071-10079
The tandem solar cell architecture is an effective way to harvest a broader part of the solar spectrum and make better use of the photonic energy than the single junction cell. Here, we present the design, synthesis, and characterization of a series of new low bandgap polymers specifically for tandem polymer solar cells. These polymers have a backbone based on the benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) units. Alkylthienyl and alkylphenyl moieties were incorporated onto the BDT unit to form BDTT and BDTP units, respectively; a furan moiety was incorporated onto the DPP unit in place of thiophene to form the FDPP unit. Low bandgap polymers (bandgap = 1.4-1.5 eV) were prepared using BDTT, BDTP, FDPP, and DPP units via Stille-coupling polymerization. These structural modifications lead to polymers with different optical, electrochemical, and electronic properties. Single junction solar cells were fabricated, and the polymer:PC(71)BM active layer morphology was optimized by adding 1,8-diiodooctane (DIO) as an additive. In the single-layer photovoltaic device, they showed power conversion efficiencies (PCEs) of 3-6%. When the polymers were applied in tandem solar cells, PCEs over 8% were reached, demonstrating their great potential for high efficiency tandem polymer solar cells. 相似文献
959.
Synthesis,CrystalStructureandInfraredSpectrumofLanthanumDinuclearCoordinationCompoundwithAlanine:〔La_2(ala)_4(H_2O)_8〕·(ClO_4)_6... 相似文献
960.
In this paper, hollow poly(styrene-co-divinylbenzene-co-methacrylic acid) microparticles possessing various morphologies were synthesized by a combination of seeded polymerization and SPG membrane emulsification. Three families of polystyrene (PS) microspheres with various molecular weights but similar diameters were fabricated by SPG membrane emulsification. These PS microspheres were used as seeds to investigate the effect of their molecular weight on the phase separation between the PS seeds and microgel-like networks formed during seeded polymerization and on the morphologies of the resultant particles. Our study revealed that three resultant microparticles possessed diameters of ca. 10?μm and hollow cavities. The shell thickness of the particles became thinner as M w increased from 3.5?×?104 to 28.0?×?104. The morphological evolution of the microparticles during seeded polymerization was monitored, and these results verified the influence of the molecular weight of the PS seeds on the phase separation behavior and hence the morphologies of the resultant particles. 相似文献