【作者】 张艳；

【导师】 许并社；

【作者基本信息】 太原理工大学 ， 材料加工工程， 2009， 博士

【摘要】 石墨插层化合物种类众多,具有丰富的价态和价电子层构型,化学反应及晶体结构类型丰富。制备石墨插层化合物探索其生长机制,进而实现对阶数及物性的调控,对于深入研究结构与物性的关联、探索石墨插层化合物的一般形成机制,最终实现按照人们的意愿设计合成功能材料具有重要意义。石墨插层化合物因其独特的物理化学性质在催化、传感、光学、磁学和电池等领域具有广泛的应用前景。发展石墨插层化合物通用合成方法及形成机制是当前功能纳米材料研究领域的热点与难点。本论文主要探索了石墨插层化合物(金属氧化物、金属氯化物、稀土氧化物和三元金属氯化物)可控合成工艺,并对所制备的材料进行了详细的表征,对它们的形成机理进行了简单的探讨。主要内容归纳如下:(1)运用化学法将石墨,盐酸(12M)和三氧化铬按一定的比例混合,在常温常压下静置15天,合成了2阶的CrO3-石墨插层化合物。通过XPS证实了在插层化合物中存在CrⅥ化合物。(2)运用混合法合成了纯5阶Cr2O3-石墨插层化合物;7阶Bi2O3-石墨插层化合物;6、7阶混合态的ZrO2-石墨插层化合物;4、5阶混合态的MoO3-石墨插层化合物;纯6阶的FeCl3-石墨插层化合物。首次运用混合法合成了5阶CoCl2-石墨插层化合物;4、5、6阶混合态的PbCl2-石墨插层化合物;5、6阶混合态BiCl3-石墨插层化合物;。在插层化合物中能形成畴,在阶次转变过程中,这些畴发生部分折叠,形成新的阶次状态,这些折叠区域仍保持较高的有序性,并逐渐增大直至形成单一阶次的插层化合物。(3)首次提出了运用水下电弧放电法合成了纯7阶的FeCl3-石墨插层化合物;纯7阶的KCl-石墨插层化合物和纯6阶的NiCl2-石墨插层化合物,它是一种简单有效的合成石墨插层化合物的方法。运用XRD分析石墨插层化合物。结果表明,对网状层面结构的天然石墨,可以利用物理的方法使一些非碳反应物(原子、分子、离子、或粒子团)插入石墨层间,从而改变石墨的层面结构,使产物出现新的物理性质和化学性质。通过XRD、HRTEM和XPS对产物相的成份进行了分析。针对不同反应阶段产物SEM像的观察,提出了石墨插层化合物的形成机理。我们认为该合成工艺为其它石墨插层化合物的合成也提供了一个新的研究方向。(4)从稀土金属氧化物的结构特征出发,首次论述了稀土金属氧化物-石墨层间化合物的合成及它们的结构特点。通过研究稀土金属氧化物对GICs结构及性能的影响,指出了稀土金属氧化物-石墨层间化合物的发展趋势及应用前景。本论文给出了最佳的工艺参数,在加热速度20-30℃/min,保温时间1h,保温温度分别为1200℃和2000℃时合成了5阶的CeO2-石墨插层化合物和Eu2O3-石墨插层化合物。(5)采用熔盐法,以NiCl2(CuCl2)与FeCl3的混合物为插层剂合成三元FeCl3-NiCl2(CuCl2)-GICs。考察了石墨与氯化物的摩尔比、NiCl2(CuCl2)与FeCl3的摩尔比、反应温度和反应时间等工艺因素对产物阶结构的影响,探讨了NiCl2(CuCl2)与FeCl3在石墨层间的插层过程。研究结果表明,改变反应体系中石墨与氯化物的摩尔比、NiCl2(CuCl2)与FeCl3的摩尔比、反应温度和反应时间,可以得到阶结构不同的FeCl3-NiCl2(CuCl2)-GICs。当石墨与氯化物的摩尔比为4:10(3:10),NiCl2(CuCl2)与FeCl3的摩尔比为3:7(6:4),反应温度为450℃(550℃),反应时间为25h(30h)时,所得产物分别为一阶和二阶FeCl3-NiCl2-GICs和FeCl3-CuCl2-GICs。反应过程中存在FeCl3先插入石墨层间,然后NiCl2逐渐替换FeCl3的插层反应机制。更多还原

【Abstract】 Graphite intercalation compounds(GICs) are a series of versatile materials with abundant chemical reactions, electronic and crystal structures. GICs have exhibited promising applications in catalysis, sensing, optics, magnetics and batteries. Developing novel synthesis methods and investigating general formation mechanism are one of the main challenges in this field. In this dissertation, systematic investigation was carried out on new synthesis strategies of GICs, their formation mechanisms and novel properties.The aim of this dissertation is to explore the controlled synthesis processes of GICs. The as-prepared nanomaterials were characterized in detail and their formation mechanism was briefly discussed. The main contents can be summarized as follows:(1) Chemical methods were used to synthesize CrO3-GICs at room temperature under atmospheric conditions. Stage-2 GICs was prepared by mixing predetermined amount of graphite, CrO3 and 12M HCl and keeping the mixture for 15 days. The presence of CrⅥin GICs synthesized was proved by X-ray photoelectron spectroscopy.(2) By the mixing method, stage 7 Bi2O3-GICs, stages 6, 7 ZrO2-GICs, stages 4, 5 MoO3-GICs, stage 5 CrO3-GICs, stage 6 FeCl3-GICs were synthesized. Stage 5 CoCl2-GICs;stages 4, 5, 6 PbCl2-GICs;stages 5, 6 BiCl3-GICs were synthesized by the mixing method for the first time. The domains formed in these GICs were partly folded, forming new stage in the stage transformation. These folding regions remained highly ordered state and gradually increased until the formation of a single stage GICs.(3) A novel one-step synthesis method of pure stage 7 FeCl3-GICs (pure stage 7 KCl, pure stage 6 NiCl2) by an arc discharge in aqueous solution was reported for the first time, which presents a simple and controllable way to synthesize GICs. The structure of the GICs was characterized by X-ray diffraction. The analysis obtained of XRD patterns indicates that a number of non-carbon reactant (atom, molecule, ion or groups) physically intercalated the layers of graphite with reticulated layer structure. Consequently the layered structure of graphite was changed and new physical and chemical properties were thus obtained. The detailed microstructures of as-synthesized products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The morphology and phase of the products were found to be strongly dependent on reaction conditions. This technique may also have great potentials in preparing other GICs. (4) On the basis of the structural characteristics of rare earth metal oxides, the synthesis and structural characteristics of rare earth metal oxides-graphite intercalation compounds(REO-GICs) were discussed for the first time. In addition, by means of studying the effect of rare earth metal oxides on the structure and properties of GICs, we pointed out the developing trend and the application prospect of REO-GICs. The suitable intercalation conditions were as follows; heating rate 20-30℃/min, treatment time 1h, and temperature 1200℃(2000℃) for stage-5 CeO2 (Eu2O3)-GICs.(5) FeCl3-NiCl2 (CuCl2)-GICs were synthesized by molten salts method. Graphite powder was used as host material and the mixture of NiCl2 (CuCl2) and FeCl3 as intercalant. The influence of reaction conditions on stage structures was discussed such as temperature, time, and graphite-to- chloride molar ratio. The results show that with the change of molar ratio among graphite, NiCl2 (CuCl2) and FeCl3, reaction time and temperature, FeCl3-NiCl2 (CuCl2)-GICs with different stages were obtained. Under the conditions of C/chlorides=4:10(3:10),NiCl2(CuCl2)/FeCl3=3:7(6:4), 450℃(550℃), 25h(30h), the products were stage 1 and stage 2 FeCl3-NiCl2 -GICs and FeCl3-CuCl2-GICs. During the reaction process, NiCl2 partially took the place of preferentially intercalated FeCl3.更多还原