热解法制备石墨烯及其机理和性能研究

发布时间：2018-06-07 06:38

  本文选题：石墨烯 + 热解　； 参考：《北京化工大学》2011年硕士论文

【摘要】：石墨烯作为碳材料中最年轻的一员,早已引起大家的广泛关注。特别是在2010年,Geim因为首次从石墨中剥离出严格意义上的石墨烯而获得诺贝尔化学奖这一殊荣,更是将对其的研究热潮推向顶峰。 石墨烯是已知世界上最薄的材料,且在力学、热学、电学、光学等方面都具有优异的性能,但是传统的制备方法并不能大量合成石墨烯,这也阻碍了其在工业中的应用。本文通过研究发现了一种新型的合成方法一热解法,可以大量制备出品质优良的石墨烯,考察了反应条件(温度、配比等)对所得产物的收率、形态和结构的影响,并对所得样品进行透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、原子力显微镜(AFM)、傅立叶红外光谱(FIIR)和拉曼光谱测试。同时将其作为锂离子电池负极材料的进行了电化学性能测试。 研究表明,此方法可以通过热解二茂铁和1,2,4-三氯苯混合物直接高收率合成石墨烯,其碳源转化率为42%,在0.5 L釜内一次可以合成8g左右。其特点是产量大,远大于传统方法所得；片层大(～10 um)而完整,层数少(3～5层)；结晶性能较好、缺陷位少。此外,本文通过改变温度和原料配比,探索出产物石墨烯产量及形貌的变化规律：(1)随着反应温度的升高,产物纯度以及结晶度提高,缺陷位减少；(2)随着炭化处理温度的升高,石墨烯片层结晶度提高,层间距先增大后减小,在700℃时最大,产物更倾向于单层石墨烯；(3)寻找出最优配比为1：1；当减少1,2,4-三氯苯的含量时,产物产量随着碳源的减少而下降,且产物形貌变化较明显,表明氯元素的含量影响了产物的形貌；当减少二茂铁的含量时,产物产量下降幅度更明显,但产物形貌无明显变化,表明催化剂的含量对产物的产量影响更大；(4)由空白样和对比样发现,氯元素是影响产物形貌的关键性因素。因此本文最后通过改变含氯碳源,分别得出碳纳米管、碳纳米带以及空心纳米球等纳米材料,并根据材料形貌随碳氯原子比的变化推测出石墨烯的合成机理以及氯元素所起的作用。 经电化学性能测试得出：该产物在50 mA·g-1电流密度下,首次放电容量为611 mAh·g-1;随着炭化温度的升高循环性能先提高后降低,700℃时达到最优,30次后可逆循环容量为413 mAh·g-1。可逆容量的变化主要是因为结晶度的提高以及层间距的变化影响了锂离子的嵌脱能力。
[Abstract]:As the youngest member of carbon materials, graphene has attracted much attention. Especially in 2010, the Nobel Prize in Chemistry for the first time to remove graphene from graphite brought its research upsurge to the top. Graphene is the thinnest material in the world and has excellent properties in mechanics, thermodynamics, electricity and optics. However, the traditional preparation method can not synthesize graphene in large quantities, which also hinders its application in industry. In this paper, a new synthetic method, pyrolysis, was found to produce graphene with high quality. The effects of reaction conditions (temperature, ratio, etc.) on the yield, morphology and structure of the products were investigated. The samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FIIR) and Raman spectroscopy. At the same time, the electrochemical performance of the cathode material for lithium ion battery was tested. The results show that this method can be used to synthesize graphene directly in high yield by pyrolysis of ferrocene and 1-trichlorobenzene. The conversion of carbon source is 42 and about 8 g can be synthesized in 0.5 L kettle. It is characterized by its large yield, which is much larger than that obtained by the traditional method, the large and complete lamellar layer (10 umps), the less layers of three layers and five layers, the better crystallization property and the less defect sites. In addition, by changing the temperature and the ratio of raw material, we find out that the change rule of graphene yield and morphology is: 1) with the increase of reaction temperature, the purity and crystallinity of the product increase, the defect position decreases with the increase of carbonization temperature. When the crystallinity of graphene lamellar increases, the interlayer spacing increases first and then decreases, and the maximum at 700 鈩，

本文编号：1990222