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31.
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
32.
Reactions with a Metalloid Tin Cluster {Sn10[Si(SiMe3)3]4}2−: Ligand Elimination versus Coordination Chemistry 下载免费PDF全文
Dr. Claudio Schrenk Birgit Gerke Prof. Dr. Rainer Pöttgen Dr. Andre Clayborne Prof. Dr. Andreas Schnepf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8222-8228
Chemistry that uses metalloid tin clusters as a starting material is of fundamental interest towards understanding the reactivity of such compounds. Since we identified {Sn10[Si(SiMe3)3]4}2? 7 as an ideal candidate for such reactions, we present a further step in the understanding of metalloid tin cluster chemistry. In contrast to germanium chemistry, ligand elimination seems to be a major reaction channel, which leads to the more open metalloid cluster {Sn10[Si(SiMe3)3]3}? 9 , in which the Sn core is only shielded by three Si(SiMe3)3 ligands. Compound 9 is obtained through different routes and is crystallised together with two different countercations. Besides the structural characterisation of this novel metalloid tin cluster, the electronic structure is analysed by 119Sn Mössbauer spectroscopy. Additionally, possible reaction pathways are discussed. The presented first step into the chemistry of metalloid tin clusters thus indicates that, with respect to metalloid germanium clusters, more reaction channels are accessible, thereby leading to a more complex reaction system. 相似文献
33.
Corrigendum: Reactions with a Metalloid Tin Cluster {Sn10[Si(SiMe3)3]4}2−: Ligand Elimination versus Coordination Chemistry 下载免费PDF全文
34.
Tatsumi Ochiai Dr. Daniel Franz Dr. Elisabeth Irran Prof. Dr. Shigeyoshi Inoue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6704-6707
The novel amino(imino)stannylene 1 was prepared by conversion of HNIPr (NIPr=bis(2,6‐diisopropylphenyl)imidazolin‐2‐imino) with one equivalent of Lappert’s tin reagent (Sn[N(SiMe3)2]2). Treatment of 1 with DMAP (4‐dimethylaminopyridine) yields its Lewis acid–base adduct 2 . The reaction of 1 with one equivalent of trimethylsilyl azide results in replacement of the amino group at the tin center by an N3 substituent with concomitant elimination of N(SiMe3)3 to afford dimeric [N3SnNIPr]2 ( 3 ). Remarkably, the reaction of 1 with B(C6F5)3 produces the novel tin(II) monocation 4 +[MeB(C6F5)3]? comprising a four‐membered stannacycle through methyl‐abstraction from the trimethylsilyl group. 相似文献
35.
Fabian Gyger André Sackmann Michael Hübner Pascal Bockstaller Dagmar Gerthsen Henning Lichtenberg Jan‐Dierk Grunwaldt Nicolae Barsan Udo Weimar Claus Feldmann 《Particle & Particle Systems Characterization》2014,31(5):591-596
Pd@SnO2 and SnO2@Pd core@shell nanocomposites are prepared via a microemulsion approach. Both nanocomposites exhibit high‐surface, porous matrices of SnO2 shells (>150 m2 g?1) with very small SnO2 crystallites (<10 nm) and palladium (Pd) nanoparticles (<10 nm) that are uniformly distributed in the porous SnO2 matrix. Although similar by first sight, Pd@SnO2 and SnO2@Pd are significantly different in view of their structure with Pd inside or outside the SnO2 shell and in view of their sensor performance. As SMOX‐based sensors (SMOX: semiconducting metal oxide), both nanocomposites show a very good sensor performance for the detection of CO and H2. Especially, the Pd@SnO2 core@shell nanocomposite is unique and shows a fast response time (τ90 < 30 s) and a very good response at low temperature (<250 °C), especially under humid‐air conditions. Extraordinarily high sensor signals are observed when exposing the Pd@SnO2 nanocomposite to CO in humid air. Under these conditions, even commercial sensors (Figaro TGS 2442, Applied Sensor MLC, E2V MICS 5521) are outperformed. 相似文献
36.
《应用有机金属化学》2017,31(10)
An efficient method for the allylation of chiral acylhydrazones derived from aldehydes has been developed to give the corresponding allylic hydrazides in good yields and diastereoselectivities. The method uses a combination of tin powder and allylic bromide as allylation system, which avoids the use of toxic allylic stannanes while retaining their merits. 相似文献
37.
G. A. Zachariadis N. M. Tzollas M. Nikolaou E. Rosenberg 《Biomedical chromatography : BMC》2013,27(3):299-305
A headspace solid‐phase micro‐extraction (HS‐SPME) method was employed in order to study the effect of storage conditions of human urine samples spiked with tributyltin (TBT) using gas chromatography and mass spectrometry. To render the analyte more volatile, the derivatization (ethylation) was made in situ by sodium tetraethylborate (NaBEt4), which was added directly to dilute unpreserved urine samples and in buffers of similar acidity. The stability of TBT in human urine matrix was compared with the stability of TBT in buffer solutions of similar pH value. Critical parameters of storage conditions such as temperature and time, which affect the stability of TBT in this kind of matrix, were examined extensively. The tests showed that the stability of TBT remains practically satisfactory for a maximum of 2 days of storage either at +4 or 20°C. Greater variations were observed in the concentration of TBT in human urine samples at +4°C and lower ones at ?20°C over a month's storage. The freeze–thaw cycles have negative effect on the stability and should be kept to a minimum. The results from spiked urine samples are also discussed in comparison to those acquired from buffer solutions of equal TBT concentration. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
38.
39.
A New Concept for Obtaining SnO2 Fiber‐in‐Tube Nanostructures with Superior Electrochemical Properties 下载免费PDF全文
Young Jun Hong Ji‐Wook Yoon Prof. Jong‐Heun Lee Prof. Yun Chan Kang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):371-376
Tin oxide (SnO2) nanotubes with a fiber‐in‐tube structure have been prepared by electrospinning and the mechanism of their formation has been investigated. Tin oxide‐carbon composite nanofibers with a filled structure were formed as an intermediate product, which were then transformed into SnO2 nanotubes with a fiber‐in‐tube structure during heat treatment at 500 °C. Nanofibers with a diameter of 85 nm were found to be located inside hollow nanotubes with an outer diameter of 260 nm. The prepared SnO2 nanotubes had well‐developed mesopores. The discharge capacities of the SnO2 nanotubes at the 2nd and 300th cycles at a current density of 1 A g?1 were measured as 720 and 640 mA h g?1, respectively, and the corresponding capacity retention measured from the 2nd cycle was 88 %. The discharge capacities of the SnO2 nanotubes at incrementally increased current densities of 0.5, 1.5, 3, and 5 A g?1 were 774, 711, 652, and 591 mA h g?1, respectively. The SnO2 nanotubes with a fiber‐in‐tube structure showed superior cycling and rate performances compared to those of SnO2 nanopowder. The unique structure of the SnO2 nanotubes with a fiber@void@tube configuration improves their electrochemical properties by reducing the diffusion length of the lithium ions, and also imparts greater stability during electrochemical cycling. 相似文献
40.
Johanna Flock Dr. Amra Suljanovic Dr. Ana Torvisco Dr. Wolfgang Schoefberger Birgit Gerke Prof. Dr. Rainer Pöttgen Prof. Dr. Roland C. Fischer Prof. Dr. Michaela Flock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15504-15517
Stabilization of the central atom in an oxidation state of zero through coordination of neutral ligands is a common bonding motif in transition‐metal chemistry. However, the stabilization of main‐group elements in an oxidation state of zero by neutral ligands is rare. Herein, we report that the transamination reaction of the DAMPY ligand system (DAMPY=2,6‐[ArNH‐CH2]2(NC5H3) (Ar=C6H3‐2,6‐iPr2)) with Sn[N(SiMe3)2]2 produces the DIMPYSn complex (DIMPY=(2,6‐[ArN?CH]2(NC5H3)) with the Sn atom in a formal oxidation state of zero. This is the first example of a tin compound stabilized in a formal oxidation state of zero by only one donor molecule. Furthermore, three related low‐valent SnII complexes, including a [DIMPYSnIICl]+[SnCl3]? ion pair, a bisstannylene DAMPY{SnII[N(SiMe3)2]2}2, and the enamine complex MeDIMPYSnII, were isolated. Experimental results and the conclusions drawn are also supported by theoretical studies at the density functional level of theory and 119Sn Mössbauer spectroscopy. 相似文献