分类号：密级：
U D C：编号：
河北工业大学硕士学位论文
论文作者：张小诗学生类别：全日制
学科门类：工学学科专业：化学工艺
指导教师：周秋香职称：教授
资助基金项目：（必要时填写）
Dissertation Submitted to
Hebei University of Technology
for
The Master Degree of
Chemical Technology
小型航空发动机PREPARATION OF GRAPHENE SHEETS BY EXFOLIATION OF GRAPHENE IN
SUPERCRITICAL ETHANOL
明史张溥传
by
Zhang Xiaoshi
Supervisor: Prof. Zhou Qiuxiang
May 2017
盖洛普路径
摘要
2012年山东高考作文石墨烯具有各种优异的理化性能使其在诸多领域具有十分广泛的应用前景，但如何高产能、低成本制备高质量的石墨烯仍是石墨烯制备的一个难题。本文采用超临界乙醇直接剥离法，分别以磷片石墨和膨胀石墨为原料成功制备了石墨烯，并且考察了分离条件及剥离试验条件对石墨烯收率的影响。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、原子力显微镜(AFM)、X射线衍射(XRD)及拉曼光谱（Raman）等分析手段对所制得的石墨烯进行表征。将石墨烯采用线棒涂布法在ABS基底上涂膜制得石墨烯薄膜，并测量其电导率；同时也考察了石墨烯作为超级电容器电极材料时的电化学性能。 以磷片石墨为原料，采用超临界乙醇剥离法制备石墨烯的适宜条件为：石墨/乙醇浓度0.32mg/ml、温度250o C、压力26MPa、剥离时间0.5h，此时石墨烯的收率最高为12.49%。随着冷热循环次数的增加，石墨烯收率随之升高，当冷热循环次数为6次时，石墨烯的收率达到最大为21.32%。对该石墨烯样品进行表征，AFM表征结果表明，石墨烯样品中94%的石墨烯片层小于8层，其中6%为单层石墨烯。XRD和拉曼的表征结果均证明了石墨烯具有较高的品质和较完整的晶格结构。
56个民族简介
以膨胀石墨为原料，采用超临界技术剥离制备石墨烯的适宜条件为：石墨/乙醇浓度0.15mg/ml、温度250 o C、压力26MPa，剥离时间为0.5h，石墨烯的收率最大为11.5%。对该石墨烯样品进行表征，从SEM以及TEM图片中可以看出，石墨烯内部存在大量的褶皱及折叠；TEM以及AFM表征证明了由该方
法可获得较大片层石墨烯，并且已测得的石墨烯片层尺寸最大可达50μm×25μm； XRD和拉曼分析结果表明，由该方法可以得到结构缺陷较少的优质的石墨烯。
以磷片石墨和膨胀石墨为原料制得的石墨烯薄膜的电导率分别为8.333×104S/m和1.033×105S/m。通过对G（FG）电极和G（EG）电极进行循环伏安法（CV）和恒电流充放电（GCD）测试，结果表明两种石墨烯均表现出较好的电化学性能：由以100mV/s 的扫描速率进行循环伏安测试，测得的电极的比电容分别为115F/g和130F/g；以6M的KOH，16A/g的电流密度，在-1.0-0.4 V的电压窗口进行充放电试验，放电比电容分别为78F/g和90F/g。
关键词：超临界乙醇，石墨烯，剥离，超级电容器，电化学性能
ABSTRACT
Graphene has a very wide range of applications due to its excellent physical and chemical characteristics. Many methods have been explored for preparation of high-quality graphene efficiently. However, it still remains a great challenge for the scalable production of graphene with low cost. In this work, supercritical ethanol was employed as medium for the exfoliation of flake graphite and expanded graphite, respectively. And the influence of processing parameters on graphene yield were systematically investigated and discussed. The graphene sheets were characterized by Scanni中美外交档案解密
ng Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and Raman Spectroscopy. The pure graphene film were fabricated on a ABS resin substrate using wire rod coating method in order to study its elelctrical properties. And the electrochemical performance of graphene as a supercapacitor electrode was also investigated.
The graphene sheets were produced in supercritical ethanol using flake graphite as starting material, the suitable preparation conditions were as follows: the initial graphite concentration 0.32mg/ml, 250o C , 26MPa and 0.5hour in exfoliation, in which the yield was about 12.49%. It could reach 21.32% at maximum after six times’ of exfoliating under the optimum condition. AFM results suggested that 94% of the layers of graphene flakes were less than 8 layers, among which 6% were monolayers. The result of XRD and Raman showed that the graphene exhibits high quality and intact lattice structure.
The graphene sheets were produced in supercritical ethanol using expanded graphite as starting material, the suitable preparation conditions were as follows: the initial graphite concentration 0.15mg/ml, 250o C, 26MPa and 0.5hour in exfoliation, in which the yield could reach 11.5%. SEM and TEM results suggested that graphene sheets exhibit common morphologies of graphene including folding and wrinkles. Analysis of TEM and AFM results revealed that the large graphenes h
ad been obtained, and the large graphenes had sizes up to 50μm×25μm. The results of XRD and Raman showed that the exfoliation process did not cause structural defects and guaranteed the high quality of graphene.
Furthermore, electrical conducticity of the resultant pure graphene films using flake graphite and expanded graphite as starting material were 8.333×104S/m and 1.033×105 S/m, respectively. The cyclic voltammetry (CV) and galvanostatic charge-discharge tests (GCD)
豫公网安备41160202000603
站长QQ:729038198
关于我们
投诉建议