NdCl3-FeCl3-石墨层间化合物的XPS研究

通过熔盐交换法合成了ＮｄＣｌ３－ＦｅＣｌ３－ＧＩＣ,采用Ｘ射线电子能谱（ＸＰＳ）分析插入剂在石墨层间的存在形式,并测定了试样中Ｎｄ,Ｆｅ,Ｃｌ和Ｃ的相对含量。ＮｄＣｌ３－ＦｅＣｌ３－ＧＩＣ中Ｆｅ２ｐ的结合能为７１１．２０－７１０．３ｅＶ,Ｎｄ３ｄ的结合能为９８３．２０－９８３．０８ｅＶ,并发现Ｆｅ在石墨层ｅ＾３＋,Ｆｅ＾２＋形式存在。     

NdCl3-FeCl3-石墨层间化合物的合成及结构模型

通过扫描电子显微镜(SEM)和能谱分析(EDS)研究了NdCl3-FeCl3-石墨层间化合物的微观形貌和元素分布. 结果表明, Nd元素插入石墨层间并形成了NdCl3-FeCl3-石墨层间化合物, 同时发现在石墨中Nd, Fe元素分布均匀. 在此实验基础上, 建立了稀土氯化物(RECl3)插入石墨的结构模型; 依据模型, 计算了RECl3-石墨层间化合物的特征层间距dPP值和间隔能指数, 计算值与实验值吻合较好, 其相对误差约为±2%; 并且发现TbCl3～LuCl3以(001)晶面插入石墨层间时, 其所需间隔能最小, 而LaCl3～GdCl3以(111)晶面为最优取向.     

石墨层间化合物FeCl3-CrO3-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420 mL·g^-1，800 ℃时达到最大膨胀容积630 mL·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。     

金属石墨层间化合物的量子化学和热力学研究

采用量子化学密度泛函B3LYP方法,对碱金属、碱土金属和过渡金属石墨层间化合物(A-GIC,AE-GIC和T-GIC)进行计算.从原子净电荷、Mulliken重叠布居和轨道电子数等角度讨论了A-GIC和AE-GIC的电子结构与成键特性,初步阐明了结构与性能的关系.根据计算结果,结合热力学分析,讨论实验上尚未知的过渡金属石墨层间化合物合成的可能性.     

聚乙烯/石墨层间化合物热降解过程的TG-FTIR研究

将含磷化合物插层石墨层间化合物(GIC)用于聚乙烯(PE)的阻燃,采用氧指数(LOI)方法评价了PE/GIC的阻燃性能,并采用热分析-红外光谱联用技术(TG-FTIR)研究了PE/GIC的热降解过程,探讨了GIC的阻燃机理。研究表明,不同含磷化合物插层GIC阻燃聚乙烯的氧指数有显著差别,其中以多聚磷酸铵-GIC的阻燃效果较好,氧指数较高。TG-FTIR研究结果表明,GIC并未显著影响PE的热降解方式,但由于GIC体积膨胀所发生的氧化还原反应导致部分PE热降解提前并发生热氧化降解,促进了后期成炭的石墨化过程。     

钕在含NdCl3体系中溶解损失的研究

测定了金属钕在ＮｄＣｌ３－ＭＣｌｎ体系、ＮｄＣｌ３－（９０．０ｗｔ％ＫＣｌｎ）（Ｍ＝Ｌｉ，Ｎａ，Ｋ，Ｃａ，Ｓｒ，Ｂａ；ｎ＝１或２）截面和ＮｄＣｌ３－ＬｉＦ体系（富ＮｄＣｌ３区）中的溶解损失。发现钕在ＮｄＣｌ３－ＫＣｌ，ＮｄＣｌ３－ＣａＣｌ２和ＮｄＣｌ３－（９０．０ｗｔ％ＫＣｌ，１０．０ｗｔ％ＣａＣｌ２）体系中溶解损失较小，而在ＮｄＣｌ３－ＫＣｌ体系中随温度的升高而加大，当体系中ＮｄＣｌ３浓度＜５０     

增大层间距对天然石墨可逆储锂性能的影响研究

利用石墨嵌入化合物(GIC)制备技术处理天然石墨, 然后在其表面包覆一层软炭前驱体, 并在惰性气氛下热处理. 所得样品不但层间距保持了拉大的状态, 而且还在天然石墨内部预留了膨胀空间. 成功地找到了在保持天然石墨粒度和碳六角平面直径不显著改变情况下, 提高石墨层间距, 预留膨胀空间的石墨改性方法. 分析表明, 石墨嵌入化合物表面含有的大量含氧官能团, 在软炭前驱体包覆石墨嵌入化合物的过程中, 含氧官能团与沥青之间的反应和石墨嵌入化合物分解产生气体的溢出阻碍了层间距和预留空间的恢复. 将这种材料用于锂离子电池负极材料, 石墨的可逆储锂容量变化不大, 但是倍率放电性能和循环性能得到明显改善. 这主要是因为加大层间距和预留膨胀空间, 拓宽了锂离子扩散通道, 降低了石墨嵌锂膨胀引起的包覆层破裂.     

基于阴离子-石墨嵌层化合物的电化学电容器

石墨可以在高电势下电化学可逆存储阴离子,有望在高电压储能器件中担当正极材料.本文介绍了基于阴离子-石墨嵌层化合物型正极材料的高比能电容器的研究进展,剖析了影响电容器性能的各方面因素,探讨了一系列表征相关电极材料储能机制的方法和手段,揭示了溶剂化效应对阴离子插嵌石墨正极电化学行为的关键性作用.并进一步概述了该种正极材料近年来在新型储能器件-双离子电池中的发展态势,展望了其应用前景和即将面临的潜在问题.     

富烯碳原子簇的石墨层间闭合形成机理

本文提出了富烯碳原子簇的石墨层间闭合形成机理，由该机理推出的许多结果与实验事实符合很好。我们认为碳原子簇自由基的快速淬灭及其淬灭速度是富烯碳原子簇形成及其丰度的决定因素。由此得出富烯碳原子簇在给定实验条件下产生的必然性，并预言不同大小的富烯碳原子簇可以通过优化实验条件选择性地合成。     

层间化合物hNB—Cu稳定性的理论研究

以分子簇为模型，用从头算方法，在６－３１Ｇ＾＊基组水平上对六方氮化硼（ｈＢＮ）进行几何全优化，再用优化构型对Ｃｕ的六方氮化硼层间化合物（ｈＮＢ－Ｃｕ）做单点计算，根据计算结果，从层间距、Ｍｕｌｌｉｋｅｎ布居、轨道相互作用、原子净电荷及前线轨道等角度分析了ｈＢＮ－Ｃｕ的电子结构及其稳定性，通过劝分析计算确认了这一层间化合物只是一个介稳结构，阐明了Ｃｕ使六方氮化硼陶瓷致密化的作用机理以及ｈＮＢ－Ｃｕ的弱抗氧化性。     

Structure Characterization of CuCl2-FeCl3-H2SO4 Graphite Intercalation Compounds

"Graphite intercalation compounds with CuCl2-FeCl3-H2SO4 were synthesized via a hydrothermal treatment at 150 oC and exfoliation method. The structure and composition of these graphite intercalation compounds were analyzed by means of X-ray diffraction, energy dispersive X-ray and high-resolution transmission electron microscopy. The results demonstrate that the CuCl2-FeCl3-H2SO4 molecules were successfully intercalated into the interlayer of the graphite sheets. The temperature dependence of magnetization was measured from 5 K to 300 K. Two antiferromagnetic transitions of the graphite intercalation compounds were observed at low temperatures. The critical transition temperatures are estimated to be about 50 and 102 K. The related magnetic properties are discussed briefly."     

Structure model and synthesis of NdCl3-FeCl3-graphite intercalation compounds

The distribution of the elements and microstructure of NdCI3-FeCI3-graphite intercalation compounds (GICs) were shown by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that Nd element intercalates into graphite, forming NdCI3-FeCI3-GICs, and the distribution of Nd and Fe is nearly even. On the basis of the data, a structure model for RECI3-GICs was founded, and the characteristic layer distance and the index of interval energy were calculated. The calculated results agree with experimental ones, and the relative errors are ±2%. Thus it can be seen that the (111) face is optimal direction for intercalation reaction of TbCl3-LuCl3, and the (001) face is that for LaCl3-GdCl3, because of the lowest interval energy.     

Thermal Decomposition of Ternary Sodium Graphite Intercalation Compounds

Graphite intercalation compounds (GICs) are often used to produce exfoliated or functionalised graphene related materials (GRMs) in a specific solvent. This study explores the formation of the Na-tetrahydrofuran (THF)-GIC and a new ternary system based on dimethylacetamide (DMAc). Detailed comparisons of in situ temperature dependent XRD with TGA-MS and Raman measurements reveal a series of dynamic transformations during heating. Surprisingly, the bulk of the intercalation compound is stable under ambient conditions, trapped between the graphene sheets. The heating process drives a reorganisation of the solvent and Na molecules, then an evaporation of the solvent; however, the solvent loss is arrested by restacking of the graphene layers, leading to trapped solvent bubbles. Eventually, the bubbles rupture, releasing the remaining solvent and creating expanded graphite. These trapped dopants may provide useful property enhancements, but also potentially confound measurements of grafting efficiency in liquid-phase covalent functionalization experiments on 2D materials.     

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.     

有关氯化钕磷酸三丁酯体系的活性及其与烷基铝反应的研究

稀土羧酸盐,如辛酸盐,硬酯酸盐和环烷酸盐等组成的催化体系对共轭双烯烃聚合具有良好的活性和定向效应。但体系中要有第三组分的存在,通常采用的是烷基氯化铝,其作用是与羧酸盐羧基进行交换反应,是形成活性中心的必要条件。氯化稀土组成的体系由于自身组成含有氯离子而排除了第三组分的使用,从而简化了聚合工艺流程,有利于研究体系组分之间的反应。但是并非所有氯化稀土都适宜于这种研究,原因在于大多数氯化稀土络合物不溶于惰性有机溶剂。如氯化稀土醇合物对共轭双烯烃聚合有着相当高的活性,但是研究氯化稀土醇合物与烷基铝的反应却有着一定的困难。     

Initial Electrode Kinetics of Anion Intercalation and De‐intercalation in Nonaqueous Al‐Graphite Batteries†

Graphitic materials with intercalated sites are considered as the mostly used positive electrode materials in nonaqueous Al batteries. Unlike the small‐size cations, the intercalation/de‐intercalation of large‐size anions into/out of graphite would induce large volume expansion and micro‐structure reconfiguration, leading to unexpected coulombic efficiency in the full cells (<95% within initial several cycles). For understanding the irreversible processes induced by anion intercalation/de‐intercalation (AlCl₄^–), here the kinetics of first two cycles for the Al‐graphite batteries have been systematically studied. To study kinetics behaviors at representative states, a combined method upon galvanostatic intermittent titration technique and electrochemical impedance spectroscopy has been carried out. The achieved diffusion coefficients of the positive electrodes assembled with different graphite sizes suggest that size effect also plays a critical role in determining the electrochemical kinetics in the mass transport in both electrolyte and graphitic layers as well as in interface reaction. The morphologies and micro‐structures of the post‐cycled graphite electrodes have been also experimentally studied, which also well supports the irreversible intercalation/de‐intercalation behaviors in graphite electrodes. The results offer a significant platform to well understand the essential factors in tailoring coulombic efficiency from a kinetic view, which would be helpful in promoting the graphite electrodes in Al batteries.