Preparation and Structural Investigation of CuCl_2 Graphite Intercalation Compounds

Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.

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.

Synthesis of NdCl_3-FeCl_3-Graphite Intercalation Compounds

NdCl3-FeCl3-graphite intercalation compounds were synthesized by means of molten salt-exchange method.Their layer structure and the relative content of the elements were investigated by X-ray diffraction, scanning electronmicroscopy and energy dispersive X-ray spectroscopy. The results show that the products are mixtures of 2, 3,4-stages,among them, the c-axis repeat distance, Ic, of stage-3 NdCl3-GIC is 1. 6536±0. 0024 nm. In addition, the mechanismof RECl3 intercalation reaction was discussed.

Study of NdCl_3-FeCl_3-Graphite Intercalation Compounds by X-Ray Photoelectron Spectroscopy

NdCl 3 FeCl 3 graphite intercalation compounds were synthesized by molten salt exchange method. The state of the intercalates and the relative contents of Nd, Fe, Cl, C in the product were determined by X ray photoelectron spectroscopy(XPS). From the XPS data, it is concluded that the binding energy of Fe2p electrons is about 711 20～710 3 eV, the binding energy of Nd3d electrons is about 983 08～983 20 eV, and Fe in the product has two valence states (Fe 3+ and Fe 2+ ).

A PRELIMINARY STUDY ON THE STABILITY OF TERNARY CoCl_2-FeCi_3 GRAPHITE INTERCALATION COMPOUNDS

The ternary CoCl2-FeCl3 graphite intercalation compounds (CoCl2-FeCl3 G/C) have been subjected to different treatments in various media. It is found that the CoCl2-FeCl3 GIC is stable 'when it is stored under conditions of opening to at-mosphere,whereas,acids,NaOH,boiling water,and heat treat-ments have different effects on the stability of the CoCl2-FeCl3 G/C.

Composites on Base of the Ultradispersed Polytetrafluoroethylene and Graphite Oxide Intercalated Compounds

Composites based on ultradispersed polytetrafluoroethylene and intercalated graphite oxide compounds with dodecahydro-closo-dodecaborates and methods of their fabrication have been developed. The fabricated composites have been characterized using XRD analysis, and optical microscopy. These composites are distinguished with completeness of their combustion, since the combustion products comprise gaseous boron fluorine-containing compounds of boron, boron trifluoride (BF3), and boron oxyfluoride ((BOF)3). Besides, these composites are characterized with increased energy capacity as compared to purely oxygen-containing compounds, since the heat of formation of boron fluorine-containing compounds is higher than that of boron oxide. Introduction of ultradispersed polytetrafluoroethylene imparts composites with hydrophobicity, thus improving their functioning properties.

Electrochemically triggered decoupled transport behaviors in intercalated graphite:From energy storage to enhanced electromagnetic applications

Pyrolytic graphite (PG) with highly aligned graphene layers,present anisotropic electrical and thermal transport behavior,which is attractive in electronic,electrocatalyst and energy storage.Such pristine PG could meeting the limit of electrical conductivity (~2.5×10^(4) S·cm^(−1)),although efforts have been made for achieving high-purity sp^(2) hybridized carbon.For manipulating the electrical conductivity of PG,a facile and efficient electrochemical strategy is demonstrated to enhance electrical transport ability via reversible intercalation/de-intercalation of AlCl_(4)^(-)into the graphitic interlayers.With the stage evolution at different voltages,variable electrical and thermal transport behaviors could be achieved via controlling AlCl_(4)^(-)concentrations in the PG because of substantial variation in the electronic density of states.Such evolution leads to decoupled electrical and thermal transport (opposite variation trend) in the in-plane and out-of-plane directions,and the in-plane electrical conductivity of the pristine PG (1.25×10^(4) S·cm^(−1)) could be massively promoted to 4.09×10^(4) S·cm(AlCl_(4)^(-)intercalated PG),much better than the pristine bulk graphitic papers used for the electrical transport and electromagnetic shielding.The fundamental mechanism of decoupled transport feature and electrochemical strategy here could be extended into other anisotropic conductive bulks for achieving unusual behaviors.

Electronic Effect of Carbon Support on Pt Catalyst Supported on Graphite Intercalation Compound

Graphite intercalation compounds（GIC） were tested as an experimental model for studying the electronic effect of carbon support on the catalytic activity and poisoning tolerance of Pt catalyst for direct methanol fuel cells. The GIC samples with different intercalation degrees were prepared by electrolyzing graphite flake in H2SO4 for varying the periods of time. The GIC-supported Pt catalyst was deposited electrochemically. The catalytic activity and poisoning tolerance of the GIC-supported Pt catalysts were evaluated. It was found that GIC with sulfate anion as intercalate was able to catalyze methanol electrooxidation, which could be related to the positive charges generated on the graphite layer upon intercalation. As intercalation degree increased, the catalytic activity of the GIC-supported Pt catalyst decreased while the poisoning tolerance improved. This suggests that electron donation from support to catalyst had great effect on both catalytic activity and poisoning tolerance of Pt catalyst. And intercalation can be adopted as another important way to make modification on carboneous catalyst support.

STUDY ON THE MICROSTRUCTURE OF Fe-KCI GRAPHITE INTERCALATION COMPOUND

The intercalatants presence of Fe-KCl graphite intercalation compound (Fe-KCl G/C) is in the form of independent crystalline phase. In this paper, its distribution in the carbon interlayer, crystalline status and powder sizes have been studied by X-ray diffraction (XRD) , small angle X-ray scattering (SAXS) and transmission electron microscope (TEM). And the partial crystal structure of the GIC has been researched too.

Doping inhomogeneity and staging of ultra-thin graphite intercalation compound flakes probed by visible and near-infrared Raman spectroscopy

When ultra-thin graphite intercalation compounds（GICs） are deposited on the SiO2/Si substrate, it is found that their colors are dependent on the thickness of GIC flakes. The sample colors of ultrathin GIC flakes can no longer provide qualitative information on the stage index. Here, multi-wavelength Raman spectroscopy is thus applied to study the doping inhomogeneity and staging of ultra-thin GICs by FeCl3 intercalation. The G band intensity of stage-1 GIC flakes is strongly enhanced by 532-nm laser excitation, while that of stage-2 and stage-3 flakes exhibits strong intensity enhancement for 785-nm laser excitation. The near-infrared lasers are suggested to probe the doping inhomogeneity and staging of ultra-thin GIC flakes.

Localized-domains staging structure and evolution in lithiated graphite

Intercalation provides to the host materials a means for controlled variation of many physical/chemical properties and dominates the reactions in metal‐ion batteries.Of particular interest is the graphite intercalation compounds with intriguing staging structures,which however are still unclear,especially in their nanostructure and dynamic transition mechanism.Herein,the nature of the staging structure and evolution of the lithium(Li)‐intercalated graphite was revealed by cryogenic‐transmission electron microscopy and other methods at the nanoscale.The intercalated Li‐ions distribute unevenly,generating local stress and dislocations in the graphitic structure.Each staging compound is found macroscopically ordered but microscopically inhomogeneous,exhibiting a localized‐domains structural model.Our findings uncover the correlation between the long‐range ordered structure and short‐range domains,refresh the insights on the staging structure and transition of Li‐intercalated/deintercalated graphite,and provide effective ways to enhance the reaction kinetic in rechargeable batteries by defect engineering.

超微粉石墨层间化合物FeCl_3-NiCl_2-GICs的制备及电磁性能研究

以微粉石墨为主体材料合成出不同阶结构的FeCl3 NiCl2 GICs。应用XRD、SEM对产物的晶体结构与表面形貌进行分析表征。采用范德保法测量产物在常温常态下的电阻率 ,用MODEL960 0振动磁强计测量GICs在 0～ 7 95 8× 10 5A m磁场强度下的磁化强度、磁化率。测量数据表明异类原子FeCl3、NiCl2 插入石黑层间后 ,GICs的电导率增加 1 3～ 2 9倍 。

用H_2O_2-H_2SO_4合成低硫GIC的研究

采用化学氧化法在浓硫酸与双氧水混合液中合成了H2SO4-GIC ,研究了插层工艺参数如双氧水浓度、双氧水与浓硫酸的配比以及水洗液的pH值、烘干温度、膨化温度等对膨胀容积和残余硫含量的影响 ,同时也对整个插层机理进行了探讨 ,得到了制造低硫膨胀石墨的合理工艺参数。

石墨层间化合物FeCl_3-CrO_3-GIC的制备及性能研究

以天然鳞片石墨、CrO3、CH3NO2、FeCl3为原料,按物质的量的比34∶1.5∶22∶1,利用化学氧化法制备出低温易膨胀、高膨胀容积的石墨层间化合物,300℃时膨胀容积为420mL·g-1,800℃时达到最大膨胀容积630mL·g-1,明显优于传统硫酸、硝酸插层的石墨层间化合物。采用SEM、EDS、FTIR、XRD、TG、VSM等技术对石墨层间化合物的组成、结构、性能进行了表征和分析。

三元FeCl_3-AlCl_3-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。

FeCl_3-GIC的结构稳定性与热稳定性研究

采用 XRD和 TG- DTA等分析方法 ,考察了混合法制备的纯一阶、二阶、三阶和四阶 Fe Cl3- GIC在空气中和某些液体介质中的结构稳定性及其热稳定性。实验结果表明 :选择适宜的 C/Fe Cl3摩尔比 ,调节反应温度和保温时间 ,采用混合法可以制备出纯一阶到纯四阶的 Fe Cl3- GIC。上述各阶 Fe Cl3- GIC在空气中相当稳定 ,在水和酸性液体介质中的稳定性较高 ,但在碱性介质和某些有机溶剂中的稳定性较差。其热分解温度约为 330℃。

宽频谱红外烟幕剂CuCl_2-NiCl_2-GIC的研究

采用定量混合法,以微粉石墨为主体材料制备出2、3阶CuCl2-NiCl2-GIC,应用XRD技术对其层间结构进行表征,结果证实所得产物以混阶形式存在,其中2、3阶CuCl2-NiCl2-GIC的周期插层面间距为1.474A和1.753A。用扫描电镜观察样品的表观形貌,并进行选区成份分析。通过考核CuCl2-NiCl2-GIC的粒度分布、沉降速度及质量消光系数,证实该物质对工作在红外波段的军用电子器材具有良好的干扰功效。

三元FeCl_3-NiCl_2-GICs的表征及微波吸收性能

以天然鳞片石墨为宿主,FeCl3、NiCl2为插层剂,通过熔盐法制备了不同阶结构的三元FeCl3-NiCl2-GICs。采用XRD、SEM、EDS等对GICs的阶结构、表面形貌及成分进行了分析,试样的导电性和微波吸收性能分别由粉末电阻率测定仪和网络矢量分析仪进行测定。结果表明,插层过程中宿主石墨沿c轴方向膨胀并在层面边缘留下侵蚀痕迹,随着阶数的升高边缘侵蚀程度逐渐减弱。不同阶结构的三元FeCl3-NiCl2-GICs中Cl元素在石墨层间均匀分布,而Fe、Ni元素在单个鳞片内则呈不均匀分布,Fe元素的相对百分含量由鳞片边缘向中心呈上升趋势,而Ni元素则完全相反。FeCl3-NiCl2-GICs的电阻率低于宿主石墨,且随着阶数的升高先降低后增大,二阶FeCl3-NiCl2-GICs的导电性最好。FeCl3-NiCl2-GICs具有较好的微波吸收性能,其最大反射损耗量随阶数增大先减小后增大。一阶FeCl-NiCl-GICs反射损耗量最大,在试样厚度为2mm时,其最大反射损耗量为-10.3dB。

石墨层间化合物GICs的形成机理探讨

将 GICs形成过程划分为熔融、活化、扩散和成键等阶段 ,分析了各阶段反应的主要影响因素 ,以氯化铜、氯化镍 GICs的合成实验为基础 ,根据 SEM对石墨膨胀前后、插层前后的形貌分析 ,以及膨胀石墨合成 GICs反应前后体积变化分析 ,认为 GICs的形成过程中 ,主要有三个机制起作用 :氯化物扩散机制、氯化物和碳原子层之间离子键牵引机制和石墨碳原子层分子键牵引回复机制。在膨胀石墨 GICs的合成过程中 ,除占主导地位的扩散机制外 ,还存在化学键牵引机制 ,主要包括碳原子间分子键牵引和碳原子氯化物之间的离子键牵引。

烟幕剂CuCl_2-FeCl_3-GIC干扰电磁波性能研究

采用定量混合法,以微粉石墨为主体材料合成出2、3阶CuCl2-FeCl3-GIC,应用XRD技术对其层间结构进行表征,结果证实所得产物以混阶形式存在,其中2、3阶CuCl2-FeCl3-GIC的特征层间距为1.281nm和1.625nm。由范德堡法测试了合成产物在常温静态下的平均电导率。并考核了CuCl2-FeCl3-GIC在激光、远红外及8mm波段的屏蔽性能,试验结果证实其对工作在上述波段的电子器材具有较强的干扰作用。