Lithium storage in single-walled carbon nanotubes

Here, we investigated the lithium insertion/extraction mechanism in single-walled carbon nanotubes (SWNTs) based both on the empty SWNTs and filled SWNTs, including ferrocene-filled SWNTs (Fc@SWNTs) and C₆₀-filled SWNTs (C₆₀@SWNTs). SWNTs, C₆₀@SWNTs and Fc@SWNTs were systematically investigated as anode materials for Li-ion batteries. The electrochemical performance of the C₆₀@SWNT electrode was slightly better than that of the SWNTs, and the reversible capacity of Fc@SWNTs per unit weight was ～1.7 times greater than that of the empty SWNTs due to its special tube internal structure. It was proved that the dominant reversible sites for lithium storage in empty SWNTs are the trigonal interstitial channels. Meanwhile, lithium can reversibly insert or extract the inner channels of the tubes after doping with ferrocene; the reversible capacity presented in the inner channels of Fc@SWNTs is about Li_1.13C₆.     

Bi‐Directional Electrocatalytic Detection of Dopamine at an Electrode Modified with Ferrocene‐Filled Carbon Nanotube Peapods

A glassy carbon electrode (GCE) was modified with nanopeapods formed by ferrocene filled single‐walled carbon nanotubes (Fc@SWNTs). The modified electrode showed bi‐directional electrocatalysis toward dopamine (DA), which suggested a synergistic effect of ferrocene and carbon nanotubes. Bi‐directional detection of DA was realized based on the modified electrode.     

Tin oxide (SnO2) nanoparticles/electrospun carbon nanofibers (CNFs) heterostructures: controlled fabrication and high capacitive behavior

Tin oxide (SnO(2))/carbon nanofibers (CNFs) heterostructures were fabricated by combining the versatility of the electrospinning technique and template-free solvent-thermal process. The results revealed that the SnO(2) nanostructures were successfully grown on the primary electrospun carbon nanofibers substrates. And, the coverage density of SnO(2) nanoparticles coating on the surface of the CNFs could be controlled by simply adjusting the mass ratio of CNFs to SnCl(4)·5H(2)O in the precursor during the solvent-thermal process for the fabrication of SnO(2)/CNFs heterostructures. The electrochemical performances of the SnO(2)/CNFs heterostructures as the electrode materials for supercapacitors were evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M H(2)SO(4) solution. At different scan rates, all the samples with different coverage densities of SnO(2) showed excellent capacitance behavior. And, the sample CS2 (the mass ratio of CNFs to SnCl(4)·5H(2)O reached 1:7) exhibited a maximum specific capacitance of 187 F/g at a scan rate of 20 mV/s. Moreover, after 1000 cycles, the specific capacitance retention of this sample was over 95%. The high capacitive behavior could be ascribed to the low resistance of SnO(2)/CNFs heterostructures and rapid transport of the electrolyte ions from bulk solution to the surface of SnO(2).     

空心球状C@SnO2@SnS2的制备及光催化去除Cr（Ⅵ）性能研究

将SnO2负载在碳球上通过不完全烧结的方法得到含有大量碳的空心状C@SnO2,随后加入TAA(硫代乙酰胺),利用离子交换法在水热过程中制备了具有不同硫化程度的空心结构的C@SnO2@SnS2三元复合物。利用XRD、FESEM、TEM、XPS、UV-Vis DRS、PL等测试手段对合成样品进行表征,并测试了其光催化去除Cr(VI)的性能。结果表明,C、SnO2和SnS2三者之间的协同作用以及空心结构的形貌显著增强了SnO2的光催化性能,其中CSS-2样品对Cr(VI)具有最佳的去除能力,太阳光照射120 min后对Cr(VI)的去除率高达98.8%。     

In-situ preparation and the characterization of Pt/SnO2

To enhance the cycling stability of Pt-based catalysts,the anti-corrosion property of support and the attachment of Pt with support should both get improved.For this purpose,a novel method is presented for in situ preparing Pt/SnO₂.The structure of Pt/ SnO₂ is characterized by X-ray diffraction（XRD） and transmission electron microscopy（TEM）,confirming the homogeneous deposition of Pt on SnO₂.The high resolution TEM（HRTEM） shows the large interfaces between Pt and SnO₂.The TEM photos recorded after accelerated durability tests with Pt/SnO₂ show that the agglomeration and size increment of Pt particles is not severe, indicating the good stability of Pt/SnO₂.The electrochemical active surface area（EAS） of Pt/SnO₂ keeps increasing during the 1000 cycles of cyclic voltammetric（CV） sweeping in H₂SO₄,while the EAS decayed by 35%when mixing Pt/SnO₂ with carbon nanotubes（CNTs）,indicating the superior anti-corrosion property of SnO₂ in contrast to CNTs.     

Inexpensive methodology for obtaining flexible SnO2-single-walled carbon nanotube composites for lithium-ion battery anodes

Journal of Solid State Electrochemistry - A versatile and low-cost methodology for fabricating free-standing carbon graphite (CG)/SnO2/single-walled carbon nanotube (SWCNT) composites as anode...     

SnO2负载Au和M-Au(M=Pt,Pd)催化剂及其低温催化氧化CO性能

以SnO₂为载体, 采用沉积沉淀法(DP)、共沉淀法(CP)和浸渍法(IM)制备了金负载Au/SnO₂催化剂, 同时采用沉积沉淀法制备了M-Au/SnO₂(M=Pd, Pt)双金属负载催化剂. 通过X射线衍射(XRD)、BET比表面积测定、透射电镜(TEM)和X射线光电子能谱(XPS)等技术对样品进行表征, 并测定其对CO的催化活性. 结果表明: 与CP法和IM 法相比, DP法制备的Au/SnO₂-DP 催化剂, Au 颗粒(<5 nm)较小, 分布均匀; Au/SnO₂-DP 中的Au 是以金属态Au0存在, 而Au/SnO₂-CP 和Au/SnO₂-IM 中, 金以Au⁰和Au³⁺的混合价态存在, 在Au/SnO₂-DP和M-Au/SnO₂中的Au、Pt、Pd和SnO₂之间存在相互作用; Au/SnO₂-DP 催化性能明显优于Au/SnO₂-CP 和Au/SnO₂-IM. Au与Pt 和Pd的双金属复合催化剂催化活性明显提高. 不同方法制备Au/SnO₂催化活性的差别主要是由于Au颗粒大小和Au氧化态的不同而产生. 而M-Au/SnO₂活性提高, 可能是由于Au与Pt 和Pd之间的相互作用.     

Organized assemblies of single wall carbon nanotubes and porphyrin for photochemical solar cells: charge injection from excited porphyrin into single-walled carbon nanotubes

Photochemical solar cells have been constructed from organized assemblies of single-walled carbon nanotubes (SWCNT) and protonated porphyrin on nanostructured SnO2 electrodes. The protonated form of porphyrin (H4P2+) and SWCNT composites form 0.5-3.0 microm-sized rodlike structures and they can be assembled onto nanostructured SnO2 films [optically transparent electrode OTE/SnO2] by an electrophoretic deposition method. These organized assemblies are photoactive and absorb strongly in the entire visible region. The incident photon to photocurrent efficiency (IPCE) of OTE/SnO2/SWCNT-H4P2+ is approximately 13% at an applied potential of 0.2 V versus saturated calomel electrode. Femtosecond pump-probe spectroscopy experiments confirm the decay of the excited porphyrin in the SWCNT-H4P2+ assembly as it injects electrons into SWCNT. The dual role of SWCNT in promoting photoinduced charge separation and facilitating charge transport is presented.     

石墨/氧化锡/活性炭锂离子电池负极材料的合成及性能

采用液相法,以SnCl2·2H2O、石墨、活性炭为原料,在油浴中共热合成石墨/氧化锡/活性炭复合材料.通过XRD和电化学测试对材料进行了表征.结果表明,样品中含有石墨和金红石SnO2·这种材料作为锂离子电池负极材料具有良好的充放电循环性能.     

二氧化锡填充多壁碳纳米管材料的制备及电化学性能

用硝酸氧化法处理多壁碳纳米管(MWCNTs), 使得MWCNTs端口打开, 长度变短, 表面得到改性. 通过二氯化锡与硝酸银反应, 过滤后的溶液在浓硝酸环境中, Sn2+在毛细作用下扩散进入碳纳米管管腔, 吸附、成核并在热处理作用下沉积, 从而制备出SnO2/MWCNTs纳米复合材料. XRD和TEM测试表明, 部分SnO2填充到MWCNTs管腔, 形成不连续的纳米颗粒. 电化学测试表明, SnO2填充的MWCNTs可以结合两者的优势, 使得复合材料的循环性能和比容量均有所改善.     

SnO_2/中空洋葱状碳纳米复合材料的制备及电化学性能

以炭黑为原料,硝酸铁为催化剂前驱体,氮气气氛下1000℃高温炭化制备了直径为40nm的中空洋葱状碳纳米颗粒(OC).用SnCl2/乙醇溶液浸渍,空气中350℃氧化得到SnO2/OC复合材料.进一步对该复合材料进行酸处理制备OC包覆的SnO2电极材料.采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和热失重分析(TGA)对OC和SnO2/OC复合材料进行表征;利用恒电流充放电和循环伏安(CV)方法对复合材料作为锂离子电池负极材料的电化学性能进行表征.结果表明:酸处理后的复合材料的循环性能得到明显改善,50次循环后可逆容量保持为446mAh·g-1,OC起到了缓冲SnO2膨胀和阻止团聚的作用.     

二氧化锡/碳气凝胶的制备与电化学性能研究

应用真空浸渍法制备二氧化锡/碳气凝胶的复合材料. XRD、BET、SEM及TEM等测试结果显示,二氧化锡纳米颗粒（5~10 nm）均匀地填充在碳气凝胶的孔道内部. 在100 mA/g的电流密度下经过100周次充放电测试,该材料的容量保持率为首次循环的61.9%.     

原位合成CoPc/SnO2的键合特性及可见光光催化活性

报道了酞菁钴(CoPc)分子原位自组装于纳米SnO2颗粒表面, CoPc大环分子与SnO2表面形成Co—O轴向相互作用, 测定了原位合成方法(标记为i)制备的CoPc/SnO2(i)与浸渍法(标记为d)制备CoPc/SnO2(d)间的结合特性, 并进行了可见光光催化表征及CoPc敏化机理探讨. 结果表明, 在结合位点数相当的情况下, CoPc/SnO2(i)结合常数比CoPc/SnO2(d)的高两个数量级, 前者的光催化效率亦比后者高32.5%(光照150 min), 且CoPc/SnO2(i)光催化稳定性较高(重复十次循环使用). 其CoPc敏化SnO2的机理为, 由于敏化剂与半导体之间存在的强相互作用, 不仅增强了光生电荷在CoPc的LUMO与SnO2半导体导带间的导入效率及光生电荷对的分离效率, 而且提高了敏化剂的负载稳定性与循环光催化效率的持续性.     

Densely Packed,Ultra Small SnO Nanoparticles for Enhanced Activity and Selectivity in Electrochemical CO2 Reduction

Controlling the selectivity in electrochemical CO₂ reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non‐precious catalyst for CO₂ electroreduction, most Sn‐based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO₂ reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra‐small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.     

Densely Packed,Ultra Small SnO Nanoparticles for Enhanced Activity and Selectivity in Electrochemical CO2 Reduction

Controlling the selectivity in electrochemical CO₂ reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non‐precious catalyst for CO₂ electroreduction, most Sn‐based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO₂ reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra‐small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix.     

SnO2-TiO2薄膜载体对Au-Pt纳米颗粒电化学性能的影响

采用真空镀膜法在玻碳(GC)电极表面修饰SnO2-TiO2薄膜, 在SnO2-TiO2/GC复合电极表面组装Au-Pt双金属纳米颗粒, 制得Au-Pt/SnO2-TiO2/GC复合电极. 通过循环伏安法(CV)研究了SnO2-TiO2薄膜载体对Au-Pt双金属纳米颗粒电化学性能的影响; 采用扫描电镜(SEM)及X射线光电子能谱(XPS)对Au-Pt在SnO2-TiO2薄膜沉积的形貌及结构进行了表征. 研究结果表明, 10 nm的Au-Pt双金属纳米颗粒均匀地组装于SnO2-TiO2薄膜表面; SnO2-TiO2薄膜载体改善了复合电极抗CO中毒能力; Au-Pt双金属合金的形成提高了Pt 对甲醇氧化的电催化能力, SnO2-TiO2薄膜载体又使Pt纳米粒子d空轨道增多, 提高了Au-Pt双金属纳米颗粒的稳定性和催化性能.     

Density functional theory study on the structural and electronic properties of low index rutile surfaces for TiO2/SnO2/TiO2 and SnO2/TiO2/SnO2 composite systems

The present study is concerned with the structural and electronic properties of the TiO2/SnO2/TiO2 and SnO2/TiO2/SnO2 composite systems. Periodic quantum mechanical method with density functional theory at the B3LYP level has been carried out. Relaxed surface energies, structural characteristics and electronic properties of the (110), (010), (101) and (00) low-index rutile surfaces for TiO2/SnO2/TiO2 and SnO2/TiO2/SnO2 models are studied. For comparison purposes, the bare rutile TiO2 and SnO2 structures are also analyzed and compared with previous theoretical and experimental data. The calculated surface energy for both rutile TiO2 and SnO2 surfaces follows the sequence (110) < (010) < (101) < (001) and the energy increases as (010) < (101) < (110) < (001) and (010) approximately = (110) < (101) < (001) for SnO2/TiO2/SnO2 and TiO2/SnO2/TiO2 composite systems, respectively. SnO2/TiO2/SnO2 presents larger values of surface energy than the individual SnO2 and TiO2 metal oxides and the TiO2/SnO2/TiO2 system renders surface energy values of the same order that the TiO2 and lower than the SnO2. An analysis of the electronic structure of the TiO2/SnO2/TiO2 and SnO2/TiO2/SnO2 systems shows that the main characteristics of the upper part of the valence bands for all the studied surfaces are dominated by the external layers, i.e., by the TiO2 and the SnO2, respectively, and the topology of the lower part of the conduction bands looks like the core layers. There is an energy stabilization of both valence band top and conduction band bottom for (110) and (010) surfaces of the SnO2/TiO2/SnO2 composite system in relation to their core TiO2, whereas an opposite trend is found for the same surfaces of the TiO2/SnO2/TiO2 composite system in relation to the bare SnO2. The present theoretical results may explain the growth of TiO2@SnO2 bimorph composite nanotape.     

A glassy carbon electrode modified with SnO2 nanofibers,polyaniline and hemoglobin for improved amperometric sensing of hydrogen peroxide

Microchimica Acta - The authors describe a glassy carbon electrode (GCE) modified with a multiporous nanofibers prepared from SnO2, polyaniline and hemoglobin, and its application to the...     

Polyvinylpyrrolidone-assisted ultrasonic synthesis of SnO nanosheets and their use as conformal templates for tin dioxide nanostructures

Single crystalline SnO nanosheets with exposed {001} facets have been prepared by an ultrasonic aqueous synthesis in the presence of polyvinylpyrrolidone, which hinders the spontaneous formation of the truncated bipyramidal SnO microcrystals and exfoliate them into layer-by-layer hierarchical structures and further into separate SnO nanosheets. The SnO nanosheets have been used as conformal sacrificial templates converted into polycrystalline SnO(2), as well as layered SnO/SnO(2) nanostructures, by calcination in air. The concept of fabrication of two-dimensional tin oxide nanostructures demonstrated here may be relevant for the crystal design of layered materials, in general.     

Preparation of band gap tunable SnO2 nanotubes and their ethanol sensing properties

SnO(2) nanotubes have been prepared via a facile hydrothermal method at low temperatures using polycarbonate (PC) membrane as a hard template. The walls of as-prepared SnO(2) nanotubes are composed of fine nanocrysalline particles and the size of SnO(2) nanocrystals could be modified by changing reaction temperature. Formation mechanism of SnO(2) nanotubes is also discussed according to the experimental results. Cathodoluminescence properties of the SnO(2) product indicated that the band gap of the nanostructures increase from 3.75 eV with a particle size 5.6 nm to 3.99 eV with a particle size 3.3 nm. The as-prepared SnO(2) nanotubes were found to show enhanced gas-sensing activity and may be used as a candidate for the fabrication of gas sensors.