碳纳米管/氧化锌纳米复合材料的制备及其形貌控制

0引言碳纳米管(CNT)优良的力学、电学、热学性能使其在材料、储能、传感等许多领域都有广泛的应用前景,近年来,以碳纳米管为载体制备的纳米复合材料因其独特的应用潜力而受到广泛关注:彭峰等[1]用FeSO4-H2O2体系修饰碳纳米管,成功地制备了由碳纳米管负载的Fe2O3催化剂;Chen等[2]用溶胶凝胶法制备了CNT/SnO复合材料,作为Li离子电池阴极材料,测试表明它的电化学性能比单独的CNT和SnO材料都有所增强;Jitianu等[3]用溶胶凝胶和水热方法得到不同形貌的TiO2/CNT复合结构,这种新型的纳米复合材料在光催化方面有着重要的应用前景。纳米Z…     

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.     

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.     

基于碳纳米管的光伏电池

碳纳米管具有独特的一维结构和优异的光电特性,是构建光伏电池的理想材料。本文主要综述了近年来碳纳米管基光伏电池的结构设计、制备方法以及碳纳米管在器件中的不同功能应用。首先概述了碳纳米管的结构和光电特性,重点讨论了碳纳米管作为光电转换材料、导电电极和载流子传输层等功能层时器件的原理、制作方法及优缺点,介绍了碳纳米管在微型光伏电池、碳纳米管/硅异质结光伏电池、染料敏化光伏电池、钙钛矿光伏电池、有机光伏电池以及柔性光伏电池中的应用,最后总结了碳纳米管基光伏电池的优势和挑战,以期为新型碳基光伏电池的设计和制作提供思路和参考。     

介孔氧化锡的制备及其在锂离子电池中的应用

采用十六烷基三甲基溴化铵(CTAB)作模板剂, SnCl4·5H2O为无机离子源在水溶液中合成了有序介孔氧化锡材料. 通过XRD、N2-吸附脱附、TEM测试手段对合成产物进行表征, 并且测试了该材料作为锂离子电池阳极的可逆容量和循环能力. 结果表明, 合成过程中氨水的加入量对制备有序结构材料至关重要, 适量的OH-离子能将Sn(ClxBry)2-单元诱导组装到表面活性剂液晶模板上; 介孔材料用于锂离子电池阳极时循环容量保持能力良好; 首次不可逆容量高于SnO2理论损失量, 原因是介孔材料将锂离子滞留在孔中.     

全酶型乙醇/氧气生物燃料电池的构筑及性能研究

本文以乙醇脱氢酶（ADH）和胆红素氧化酶（BOD）为生物催化剂,以碳纳米管为电极材料,构筑了全酶型乙醇/氧气生物燃料电池. 将乙醇脱氢酶负载于单壁碳纳米管（SWCNT）上,采用亚甲基绿（MG）为NADH的电化学催化剂,实现乙醇的生物电化学催化氧化,制备了生物燃料电池ADH/MG/SWCNT/GC的电极（阳极）. 同时,将胆红素氧化酶固定于单壁碳纳米管上,通过其直接电子转移,实现了氧气的生物电化学催化还原,制得生物燃料电池的BOD/SWCNT/GC阴极. 据此构筑了全酶型的无膜生物燃料电池,在空气饱和40 mmol·L^-1乙醇磷酸缓冲溶液中该电池开路电压为0.53 V,最大输出功率密度为11 μW·cm^-2. 以商品化伏特酒作为燃料,该生物燃料电池最大输出功率为3.7 μW·cm^-2.     

三维多孔碳负载氧化锡并协同氟化锂制备高性能锂离子阳极

新型多孔碳纳米片/碳纳米管(PC/CNT)材料表现出丰富的分级孔隙结构,具有较高的氧化锡(SnO2)负载量.通过PC和CNT交联形成的三维结构能够有效地提高锂离子传输速率和电子的传导.此外,在电极中掺杂的氟化锂(LiF)不仅能够降低SnO2-PC/CNT-LiF电极的电荷转移电阻,而且还能补充SEI膜形成时消耗的Li+...     

作为锂离子电池负极材料的三维有序大孔SnO2的 制备及表征

通过聚苯乙烯(PS)胶晶模板法合成了三维有序大孔(3DOM) SnO2. 运用扫描电镜、热重分析、X射线衍射、电化学充放电等多种方法对其结构和性能进行了表征和研究. SEM图表明PS胶晶模板微球排列规整, 大小均匀(直径275±10 nm), 形成多层六方紧密堆积排列; 煅烧除去模板后的3DOM SnO2呈三维多孔网络结构, 具有圆型和六边形的孔隙形貌, 其孔径大小为(215±10) nm; 孔壁由SnO2纳米晶粒组成, 壁厚为20～30 nm. XRD图谱表明经过煅烧除去模板后, 形成了纯SnO2相. 当作为锂离子电池负极材料时, 3DOM SnO2表现出较好的充放电容量和库仑效率. 此外, 这种合成方法简单、经济, 可进一步应用于其它锂离子电池材料的合成.     

溶胶-凝胶法可控制备氧化锡纳米晶包覆碳纳米管

采用溶胶-凝胶法制备了氧化锡纳米晶包覆的碳纳米管。自由Sn4+离子从稳定的Sn柠檬酸配合物中缓慢释放出来,迁移到碳纳米管上,并在碳纳米管上沉积形成了SnO2纳米晶,沉积过程完全为异相成核方式,在碳纳米管外并没有发现单独的SnO2纳米晶。这种溶胶-凝胶方法还可以用来制备无氯离子污染的、低团聚的纯SnO2纳米晶。     

纳米锡锌复合氧化物贮锂材料的合成和性质

用液相沉淀-热解法合成了一系列结构和组成不同的锂离子电池纳米锡锌复合氧化物贮锂材料, 通过XRD、TEM和电化学测试对材料进行了表征. 测试结果表明, 非晶态ZnSnO3负极材料的初始可逆贮锂容量为844 mA·h/g, ZnO·SnO2负极材料的初始可逆贮锂容量为845 mA·h/g, SnO2·Zn2SnO4复合物负极材料初始可逆贮锂容量为758 mA·h/g, 循环10周后, 三者的充电容量分别为695, 508和455 mA·h/g, 表明非晶态结构的锡锌复合氧化物具有较好的电化学性质, 随着样品中晶体的形成, 该类型负极材料的贮锂性能下降.     

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.     

SnO2 hollow nanospheres assembled by single layer nanocrystals as anode material for high performance Li ion batteries

SnO₂ hollow nanospheres were successfully synthesized via a facile one-step solvothermal method.Characterizations show that the as-prepared SnO₂ spheres are of hollow structure with a diameter at around 50 nm,and especially,the shell of the spheres is assembled by single layer SnO₂ nanocrystals.The surface area of the material reaches up to 202.5 m²/g.As an anode material for Li ion batteries,the sample exhibited improved electrochemical performance compared with commercial SnO₂ particles.After cycled at high current rate of 0.5 C,1 C and 0.5 C for 20 cycles,respectively,the electrode can maintain a capacity of 509 mAh/g.The suitable shell thickness/diameter ratio endows the good structural stability of the material during cycling,which promises the excellent cycling performance of the electrode.The large surface area and the ultra thin shell ensure the high rate performance of the material.     

SnO2 nanosheets grown on graphene sheets with enhanced lithium storage properties

We demonstrate a new hydrothermal method to directly grow SnO(2) nanosheets on a graphene oxide support that is subsequently reduced to graphene. This unique SnO(2)/graphene hybrid structure exhibits enhanced lithium storage properties with high reversible capacities and good cycling performance.     

Hydrothermal synthesis of Zn2SnO4 as anode materials for Li-ion battery

Spinel Zn2SnO4 particles with the cubic shape are prepared via a hydrothermal reaction under mild conditions. The hydrothermal conditions, such as alkaline concentration, reaction temperature, and duration time, have an important influence on the product structure and the performance of the electrode prepared with the product. The optimized product is cube-shaped Zn2SnO4 crystalline, which is prepared with 0.4 M of NaOH solution at 200 degrees C for 24 h. These cube-shaped Zn2SnO4 particles with the spinel structure exhibit a large electrochemical capacity of 988 mA h/g and a relatively good capacity retention as anode materials for Li-ion battery. The structures of the as-prepared product and specimens taken from the electrodes after charging-discharging cycles are analyzed by X-ray diffraction, scanning electron microscopy, and transition electron microscopy techniques. In particular, it is found for the first time that the spinel Zn2SnO4 structure exists to a great extent after the first cycle and contributes to the extremely high reversible capacity during the following cycles.     

Preparation of Ru-doped SnO2-supported Pt catalysts and their electrocatalytic properties for methanol oxidation

Ru-doped SnO2 nanoparticles were prepared by chemical precipitation and calcinations at 823 K. Due to high stability in diluted acidic solution, Ru-doped SnO2 nanoparticles were selected as the catalyst support and second catalyst for methanol electrooxidation. The micrograph, elemental composition, and structure of the Ru-doped SnO2 nanoparticles were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, respectively. The electrocatalytic properties of the Ru-doped SnO2-supported Pt catalyst (Pt/Ru-doped SnO2) for methanol oxidation have been investigated by cyclic voltammetry. Under the same loading mass of Pt, the Pt/Ru-doped SnO2 catalyst shows better electrocatalytic performance than the Pt/SnO2 catalyst and the best atomic ratio of Ru to Sn in Ru-doped SnO2 is 1/75. Additionally, the Pt/Ru-doped SnO2 catalyst possesses good long-term cycle stability.     

Metal oxide and sulfide hollow spheres: layer-by-layer synthesis and their application in lithium-ion battery

A novel layer-by-layer approach has been developed to synthesize polycrystalline SnO(2) hollow spheres with tunable shell thickness and size using SiO(2) spheres as a template. The surface of the SiO(2) spheres has been first modified by the polyelectrolyte, and subsequently, the compact SnO(2) layer has deposited on the surface of the SiO(2) spheres through a redox reaction because of the electrostatic attraction between the charged species. After HF etching treatment, the uniform SnO(2) hollow spheres have been obtained. The approach presented herein has been extended to synthesize other metal oxide and sulfide hollow spheres such as In(2)O(3) and ZnS. Moreover, the as-synthesized SnO(2) hollow spheres have been applied in lithium-ion battery and show improved performance compared with SnO(2) nanoparticles. The high surface area and stable hollow structure of the SnO(2) hollow spheres may be responsible for the improved performance.     

Morphological and photoelectrochemical characterization of core-shell nanoparticle films for dye-sensitized solar cells: Zn-O type shell on SnO2 and TiO2 cores

Core-shell type nanoparticles with SnO2 and TiO2 cores and zinc oxide shells were prepared and characterized by surface sensitive techniques. The influence of the structure of the ZnO shell and the morphology ofnanoparticle films on the performance was evaluated. X-ray absorption near-edge structure and extended X-ray absorption fine structure studies show the presence of thin ZnO-like shells around the nanoparticles at low Zn levels. In the case of SnO2 cores, ZnO nanocrystals are formed at high Zn/Sn ratios (ca. 0.5). Scanning electron microscopy studies show that Zn modification of SnO2 nanoparticles changes the film morphology from a compact mesoporous structure to a less dense macroporous structure. In contrast, Zn modification of TiO2 nanoparticles has no apparent influence on film morphology. For SnO2 cores, adding ZnO improves the solar cell efficiency by increasing light scattering and dye uptake and decreasing recombination. In contrast, adding a ZnO shell to the TiO2 core decreases the cell efficiency, largely owing to a loss of photocurrent resulting from slow electron transport associated with the buildup of the ZnO surface layer.     

具有独特电子结构的锌掺杂SnO2介导形成氧空位实现高效稳定的光催化降解甲苯

室内家具和工业生产排放的挥发性有机化合物(VOCs)是典型的空气污染物,对环境和人类健康造成严重威胁.然而,目前广泛应用的二氧化钛(P25)光催化剂在降解VOCs,尤其是降解芳香烃的过程中,存在光催化转化率低,失活快等问题.因此,开发具有高效和稳定性的新型光催化剂来降解VOCs,并将其实际应用是重要的科学问题.SnO₂是一种稳定无毒的半导体光催化剂,但电子和空穴的复合率较高.掺杂过渡金属离子后可以提供缺陷态来抑制催化剂电子空穴对的快速复合,促进界面电荷转移.相比其他金属离子,Zn²⁺与Sn⁴⁺的离子半径非常相近,因此Zn²⁺会很容易掺杂到SnO₂晶格中.并且用Zn²⁺取代Sn⁴⁺会形成表面修饰,即形成更多的氧空位(SOVs)来补偿正电荷.氧空位的存在不仅会产生缺陷能级,而且还可以促进大量局域电子的累积.SnO₂上氧空位和Zn掺杂结构的协同作用可以弥补单一的外源离子掺杂或产生氧空位的不足.因此,本文采用一种简便的一步法合成催化剂Zn-SnO₂,即在SnO₂上同时实现Zn掺杂和形成SOVs,利用两者对SnO₂的协同作用提高电荷转移和分离效率,使其在低或高相对湿度条件下均表现出高效、稳定的光催化降解甲苯性能.采用低温固态电子顺磁共振(EPR)检测了催化剂中的氧空位,在纯SnO₂中仅检测到弱的EPR信号,而Zn-SnO₂上的EPR信号非常强,表明Zn²⁺的掺杂诱导产生了大量的氧空位.扫描电镜和透射电镜结果表明,掺杂Zn²⁺可以有效抑制SnO₂纳米粒子的晶体生长和相变,使得掺杂Zn²⁺的SnO₂粒子的粒径显著减小,从而导致SOVs含量增加,此外粒径的减小有利于增大其比表面积,增加活性吸附位点.紫外可见漫反射结果表明,Zn-SnO₂拓宽了光吸收范围,这归因于锌掺杂和氧空位的协同作用.在紫外光照射下,Zn-SnO₂的光催化降解甲苯性能优于纯SnO₂和P25,降解率达到77.5%.ESR光谱结果表明,Zn-SnO₂上的电子自旋共振信号强度均强于纯SnO₂和P25,说明Zn-SnO₂具有较好的氧化能力,也与DFT计算O₂和H₂O的吸附能结果相吻合,表明了锌掺杂和SOVs对SnO₂的协同作用可以显著提高电荷转移和分离效率.最后,通过原位红外光谱和DFT计算方法对甲苯降解的机理进行了研究.结果表明,甲苯的苯环在纯SnO₂表面倾向于在苯甲酸阶段打开,在Zn-SnO₂表面更倾向于在苯甲醛阶段选择性地开环.可见,Zn-SnO₂光催化剂缩短了甲苯的降解路径,并能显著抑制中间毒副产物产生.综上,本工作提供了一种安全,高效和可持续的降解VOCs的光催化剂.     

Hierarchical Mesoporous SnO Microspheres as High Capacity Anode Materials for Sodium‐Ion Batteries

Mesoporous SnO microspheres were synthesised by a hydrothermal method using NaSO₄ as the morphology directing agent. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM) analyses showed that SnO microspheres consist of nanosheets with a thickness of about 20 nm. Each nanosheet contains a mesoporous structure with a pore size of approximately 5 nm. When applied as anode materials in Na‐ion batteries, SnO microspheres exhibited high reversible sodium storage capacity, good cyclability and a satisfactory high rate performance. Through ex situ XRD analysis, it was found that Na⁺ ions first insert themselves into SnO crystals, and then react with SnO to generate crystalline Sn, followed by Na–Sn alloying with the formation of crystalline NaSn₂ phase. During the charge process, there are two slopes corresponding to the de‐alloying of Na–Sn compounds and oxidisation of Sn, respectively. The high sodium storage capacity and good electrochemical performance could be ascribed to the unique hierarchical mesoporous architecture of SnO microspheres.     

氢氧化镍/多壁碳纳米管复合材料的溶剂热法制备及电容性能

采用溶剂热法制备了氢氧化镍/多壁碳纳米管[Ni(OH)2/MWCNTs]复合纳米材料;借助X射线衍射仪和透射电镜分析了产物的结构和形貌,利用循环伏安测试测定了复合材料的电容特性.结果表明:片状β-Ni(OH)2较好地附着在MWCNTs上;复合样品的循环伏安行为明显有别于空白样品Ni(OH)2,峰电流较高.这表明引入MWCNTs可改善Ni(OH)2的电化学性能.与此同时,当MWCNTs的质量分数为10%时,相应的Ni(OH)2/MWCNTs复合物的氧化还原峰电位差最小,循环可逆性最佳.