膨胀石墨CuCl2-NiCl2-层间化合物磁性研究

在膨胀石墨ＣｕＣｌ_２－ＮｉＣｌ_２－ＧＩＣｓ合成和电性研究基础上,采用ＭＯＤＥＬ１５５振动磁强计测量了ＧＩＣｓ在０～７．９５８×１０^５Ａ／ｍ磁场强度下的磁化强度、磁化率．发现ＣｕＣｌ_２－ＮｉＣｌ_２引入石墨层间,形成ＧＩＣｓ后磁性升高．与膨胀石墨相比,ＧＩＣｓ的磁化率大约提高了２～３个数量级．ＧＩＣｓ的磁性不但由石墨的抗磁性转变成为顺磁性,磁化曲线斜率由负变正,而且随着阶结构、 ＣｕＣｌ_２和 ＮｉＣｌ_２比例变化, ＧＩＣｓ磁性发生变化．氯化镍含量在 ５０％以下,表现为强烈的顺磁性;５０％时,磁化曲线出现最大值,表现为铁磁性．＞５０％,达到６０％、８０％时,铁磁性更明显．ＧＩＣｓ阶数升高,铁磁性降低．     

膨胀石墨CuCl2-EGICs的微观结构TEM研究

采用透射电镜研究了以膨胀石墨为主体材料合成的ＣｕＣｌ２－ＥＧＩＣｓ微观结构,包括垂直和平行石墨碳原子层的层间结构,层面结构,根据Ｘ射线衍射参数计算获得２、３、４阶ＣｕＣｌ２－ＥＧＩＣｓ的层间距Ｉｃ值,与理论计算值近拟。     

超微粉石墨层间化合物CuCl_2-NiCl_2-GICs合成及电学性能

常规的ＧＩＣｓ合成原料均采用合成石墨或者粒度较粗的天然石墨，这里采用超微粉石墨作原料，进行受主金属氯化物ＣｕＣｌ２－ＮｉＣｌ２－ＧＩＣ的合成研究。使用山东南墅石墨（３０００目）、Ｃｕ－Ｃｌ２和ＮｉＣｌ２（５ｎ：０．５∶０．５摩尔比），在５２８℃、真空度１０．３Ｐａ条件下，得到超微粉的ＣｕＣｌ２－ＮｉＣｌ２－ＧＩＣｓ，ＳＴＥＭ单原子能谱扫描结果显示出铜离子和镍离子分布基本均匀。合成的１，２，３和４阶ＧＩＣｓ的电导率分别为１．５３６×１０４，１．６３８×１０４，３．７７３×１０４，和５．７２７×１０４。而石墨原料的电导率为１．８５１×１０４，从整体来看合成的ＧＩＣｓ的电导率是石墨原料的０．８－３倍。对比合成的ＧＩＣｓ的电导率发现，阶数不同，电导率不同，并且随着阶数的升高，电导率增大。     

超微粉石墨层间化合物CuCl2—NiCl2—GICs合成及电学性能

常规的ＧＩＣｓ合成原料均采用合成石墨或者粒度较粗的天然石墨，这里采用超微粉石墨作原料，进行受主金属氯化物ＣｕＣｌ２－ＮｉＣｌ２－ＧＩＣ的合成研究。使用山东南墅石墨（３０００目）、Ｃｕ－Ｃｌ２和ＮｉＣｌ２（５ｎ：０．５：０．５摩尔比），在５２８℃，真空度１０．３Ｐａ条件下，得到超微粉的ＣｕＣｌ２－ＮｉＣｌ２－ＧＩＣｓ，ＳＴＥＭ单原子能谱扫描结果显示出铜离子和镍离子分布基本均匀，合成的１，２，３和４阶     

膨胀石墨CuCl2-EGICs的微观结构TEM研究

采用透射电镜研究了以膨胀石墨为主体材料合成的ＣｕＣｌ_２－ＥＧＩＣｓ微观结构,包括垂直和平行石墨碳原子层的层间结构、层面结构．根据Ｘ射线衍射参数计算获得２、３、４阶ＣｕＣｌ_２－ＥＧＩＣｓ的层间距Ｉ_ｃ值,与理论计算值近似．选区电子衍射获得面内结构参数．发现ＥＧＩＣｓ衍射斑点是由石墨碳原子层单斑点和氯化物层多斑点簇组两套相迭而成．ＥＧＩＣｓ层面内碳原子层原子排布保持了石墨六角网格状的特点;氯化钢分子相对碳原子层分布有三种堆垛方式．倒易点分析认为有（２ｘ２）Ｒ（３０°）、（７^1/2ｘ７^1/2）Ｒ（０°）、（３^1/2ｘ３^1/2）Ｒ（０°）三种超晶格结构．二阶、三阶ＣｕＣｌ_２－ＧＩＣ中氯化铜点阵与碳原子点阵之间存在３０°的偏转角,而在一阶ＣｕＣｌ_２－ＧＩＣ中偏转角等于零度．根据高分辨电镜（ＨＲＥＭ）、选区电子衍射（ＳＡＤ）、能谱微区成分、光电子能潜（ＸＰＳ－ＥＳＣＡ）和俄歇电子能谱（ＸＡＥＳ）等结果,探讨和分析了ＣｕＣｌ_２－ＥＧＩＣｓ微观结构．     

GICs结构,性能及应用研究分析

本文系统介绍和分析了ＧＩＣｓ的概念，分类、结构性能研究现状及ＧＩＣｓ的结构与性能的相互关系。提出了ＧＩＣｓ应用研究的新线索：ＧＩＣｓ－Ｆｕｌｌｅｒｅｎｅ复合材料、ＧＩＣｓ薄膜、ＧＩＣｓ离子导体、ＧＩＣｓ定向催化剂，ＧＩＣｓ高温高导电电要的磁性记录材料等。     

混合法制备FeCl3-石墨层间化合物的初步研究

研究了混合法制备ＦｅＣｌ３－ＧＩＣ的反应温度、反应时间和Ｃ／ＦｅＣｌ３摩尔比对产物阶结构的影响。结果表明：反应温度是影响产物阶结构的主要因素;随着反应时间延长和Ｃ／ＦｅＣｌ３摩尔比减小,产物中低阶相的量增大,共存石墨减少;在适宜的条件下可制得纯一阶的ＦｅＣｌ３－ＧＩＣ。     

分步插层法制备硝酸盐-硫酸-GIC

通过硫酸、硝酸或硝酸盐分步插层的方法,成功制备了硝酸/硝酸盐-硫酸-GIC三元石墨层间化合物.采用XRD、SEM和EDS对GIC的结构进行了研究.结果表明:与直接插层法相比,分步插层法有利于插层物质的插层反应,充分扩大石墨层间距,形成低阶石墨层间化合物,使膨胀效果更优,膨胀体积高达450mL/g以上;膨胀后GIC的孔结构均匀,层壁较薄,片层结构清晰,膨胀充分.同时,分步插层法能够降低实验操作的危险性,污染小,反应易于控制.     

再次插入法制备超大膨胀体积石墨层间化合物(英文)

为进一步增大膨胀石墨的膨胀体积,用二次插入的方法制备了石墨层间化合物。首先用化学氧化法制备了膨胀体积为250mL/g的可膨胀石墨,然后以膨胀体积为250mL/g的可膨胀石墨为原料,用二次插入的方法制备了膨胀体积为380mL/g的膨胀石墨。讨论了各种反应物比率、反应温度和反应时间对膨胀体积的影响。对制得的膨胀石墨进行了各种表征,XRD谱显示产物保持了天然石墨的层状晶体结构,但是产物的石墨层间距离增大。扫描电镜照片显示通过二次插入石墨层间确实被进一步打开。结果显示这种新的制备方法是可行的,它为纳米石墨材料的研究提供了新的思路。     

制备无硫低氮膨胀石墨的新工艺研究

本文报道了一种用硝酸与丙酸的混合液为插层试剂,制备无硫低氮可膨胀石墨的新方法。它的组成和结构分别用元素分析和质谱进行确定。Ｘ射线衍射分析表明本方法合成的石墨层间化合物具有混合阶结构。产品的膨胀窖为３２０ｍＬ／ｇ,氮含量为１．６３％,不含硫。     

利用层间化合物制备载Pt催化剂

通过利用Pt(IV)-GICs和Pt(IV)乙炔黑层间化合物来制备应用于甲醇电氧化石墨和乙炔黑载铂催化剂。具体过程如下在惰性气氛下,利用H     

三元FeCl3-AlCl3-GIC的制备及其插层反应过程的研究

采用混合熔融盐法制备以天然鳞片石墨作宿主、以FeCl3和AlCl3为插层剂的GIC。通过考察反应温度、碳与金属氯化物的摩尔比以及保温时间对产物阶结构的影响，探讨了FeCl3和AlCl3在石墨层间的插层反应过程。实验结果表明：调节和控制插层反应条件，可以得到一阶FeCl3-GIC和一阶AlCl3-GIC相对含量不同的三元FeCl3-AlCl3-GIC。插层过程中存在通过生成中间产物AlFeCl6，以FeCl3逐渐替换AlCl3的插层反应机制。替换量随插层反应温度的升高、保温时间的延长和碳与金属氯化物的摩尔比的降低而增大。     

熔盐法合成金属氯化物-石墨插层化合物的判据

研究了熔融盐状态下金属氯化物-石墨层间化合物的合成判据.根据插层反应热动力学及化学键理论,选取元素的电负性和离子势作为键参数,并设计键参数函数λ为客体材料的遴选判据.基于键参数函数图对金属氯化物发生插层反应的难易程度和产物稳定性进行理论预估.研究结果表明:键参数函数图中λ≤1.2区域内的金属氯化物在700℃以下即可发生插层反应,且所得产物较为稳定;在1.2≤λ≤1.8区域内相应的客体材料在低温下很难单独插入石墨层间,常与低熔点氯化物形成共熔体后一起插入石墨层间;在λ≥1.8区域内大多为碱金属氯化物和碱土金属氯化物,理论分析认为这类物质的插层反应不适宜采用熔盐法.     

Effects of processing parameters on the structure and amount of intercalation of copper chloride-graphite intercalation compounds

Natural graphite powders were intercalated with copper chloride using gas phase reaction in this study. The effects of intercalation temperature, time, and the amount of intercalants on the structure and the amount of intercalation were investigated. An electron probe x-ray microanalyzer (EPMA) was used to quantitatively measure the copper concentration in copper chloride-graphite intercalation compounds. Only stage 1 and stage 2 structures were found in the present processing conditions and the stage structure is mainly determined by the reaction temperature. Results of EPMA quantitative measurement indicated that the amount of intercalation increased with increasing intercalation temperature. However, the amount of intercalation was independent of the reaction time due to the small particle size of graphite host materials.     

Electrical Properties of Expanded Graphite Intercalation Compounds

The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as that of the expanded graphite, and about 10 times as high as that of GIC made of the non-expanded graphite. The microanalysis results of chemical compounds by X-ray energy spectrum scanning of TEM testified that the atomic ratio of chloride and cupric is nonstoichoimetric. The multivalence and exchange of electrovalence of the cupric ion was confirmed by the XPS-ESCA. Vacancy of chlorine anion increases the concentration of charge carrier. The special stage structure, made of graphite and chloride, produces a weak chemical bond belt and provides a carrier space in the direction of GIC layer. These factors develop the electrical properties.     

The interrelationship of graphite intercalation compounds,ions of aromatic hydrocarbons,and coal conversion

The strongest similarity between ionic aromatic compounds, as potassium naphthalenide, and intercalation compounds of graphite, as C₈K, is charge transfer. Although the intercalation compounds of graphite may properly be viewed as “infinite aromatic radical ions”, the $\text{presence}$ of neutral guest species (as potassium atoms) and the $\text{absence}$ of edge positions creates a chemistry of graphite distinct from that of the aromatic ion counterparts. Proposed analogies between graphite intercalation and the chemistry of coal in gasification and in reaction with metal halides must be accepted with caution. Furthermore, while potassium naphthalenide in tetrahydrofuran will intercalate graphite, it reacts primarily with heteroatom functionality in bituminous coals.     

Lithium deintercalation in LiFePO4 nanoparticles via a domino-cascade model

Lithium iron phosphate is one of the most promising positive-electrode materials for the next generation of lithium-ion batteries that will be used in electric and plug-in hybrid vehicles. Lithium deintercalation (intercalation) proceeds through a two-phase reaction between compositions very close to LiFePO(4) and FePO(4). As both endmember phases are very poor ionic and electronic conductors, it is difficult to understand the intercalation mechanism at the microscopic scale. Here, we report a characterization of electrochemically deintercalated nanomaterials by X-ray diffraction and electron microscopy that shows the coexistence of fully intercalated and fully deintercalated individual particles. This result indicates that the growth reaction is considerably faster than its nucleation. The reaction mechanism is described by a 'domino-cascade model' and is explained by the existence of structural constraints occurring just at the reaction interface: the minimization of the elastic energy enhances the deintercalation (intercalation) process that occurs as a wave moving through the entire crystal. This model opens new perspectives in the search for new electrode materials even with poor ionic and electronic conductivities.     

Conversion of graphite intercalation compounds to carbon materials containing polymetallic nanoparticles

We report the formation of ternary graphite intercalation compounds (GICs) with FeCl₃ and PtCl₄ via reaction between hexachloroplatinic acid and a binary GIC with iron(III) chloride. Mössbauer spectroscopy and X-ray microanalysis results show that ternary GICs form only when the interlayer spaces in the parent binary GIC are incompletely occupied (stage III or lower). The coexistence of different chloride molecules in the ternary GIC leads to the formation of intermetallic nanoparticles when the material is reduced. The yield of the intermetallic phase increases with decreasing graphite particle size.     

Preparation of AgX (X = Cl, I) nanoparticles using ionic liquids

Nanoparticles of silver halides have been prepared by mixing silver halide powder with a single liquid phase consisting of an ionic liquid, isooctane, n-decanol and water. Much higher nanoparticle concentrations may be formed with ionic liquids using this new simple method than are found with conventionally applied surfactants. This method also emphasizes the applicability of ionic liquids as versatile components in microemulsions and as solvents for the synthesis of nanomaterials. The effect on the nanoparticles of changing the composition of the liquid mixtures and the nature of the ionic liquid is analysed. High nanoparticle concentrations were only found with chloride based ionic liquids, indicating the importance of the ionic liquid anion in the mechanism of the reaction.     

Potentials of Graphite Nitrate Formation during Spontaneous and Electrochemical Graphite Intercalation

Earlier and new results on spontaneous and electrochemical intercalation reactions of highly oriented pyrolytic graphite and nitric acid in a wide range of HNO₃ concentrations are summarized and analyzed. The oxidizing capacity of the solution is shown to determine the extent of intercalation and the stage index of the resulting graphite intercalation compound (GIC), as in the graphite–H₂SO₄ system. The final potential of graphite nitrate after spontaneous intercalation coincides with the potential E _Ag/AgCl in HNO₃. During the reaction of graphite with an HNO₃ solution, the potential of graphite nitrate varies monotonically, in contrast to the steplike variation inE in the C–H₂SO₄–oxidant system. The behaviors of Brönsted acids which can and cannot spontaneously intercalate into graphite are compared. It is shown that the anodic polarization of graphite in HNO₃ offers the possibility of controlling the potential and stage index of the resulting GIC by varying the HNO₃ concentration and current. During anodic polarization in 75–98% HNO₃ at I= 30–100 A, the interplay between the spontaneous and electrochemical oxidation processes leads to the formation of stage II graphite nitrate, irrespective of the charge passed, and notably reduces the intercalation rate. This effect is interpreted in terms of the intercalation mechanism and sorption processes. The data on the anodic polarization of graphite at small currents point to fundamental differences in electrochemical behavior between the intercalants that can (HNO₃) and cannot (H₂SO₄) spontaneously intercalate into graphite. The concentration ranges and potentials of the formation of stage I and II graphite nitrates via anodic oxidation in HNO₃ are determined. The electric current is shown to influence the potential of formation of the stage I GIC: the minimal potential of graphite nitrate formation in 98% HNO₃ is E _Ag/AgCl = 1.34 V (I= 500 A). The potentialities of the spontaneous and electrochemical intercalation reactions for the controlled synthesis of graphite nitrate with a particular stage index are compared.