1、化学与材料论文化学与材料论文石墨烯 一( 前言 石墨烯是目前发现的唯一存在的二维自由态原子晶体, 它是构筑零维富勒烯、一维碳纳米管、三维体相石墨等sp2 杂化碳的基本结构单元, 具有很多奇异的电子及机械性能。因而吸引了化学、材料等其他领域科学家的高度关注。本文介绍了近几年石墨烯的研究进展, 包括石墨烯的合成、去氧化、化学修饰及应用前景等方面的内容。石墨烯由于其特殊的电学、热学、力学等性质以及在纳米电子器件、储能材料、光电材料等方面的潜在应用,引起了科学界新一轮的热潮。 二(石墨烯的生产加工方法及化学原理 物理方法: 1.微机械剥离法: 通过机械力从新鲜石墨晶体的表面剥离石墨烯片层。 2.印章切
2、取转移印制法: 在印章突起的表面上涂上一层转换层( 可用树脂类材料通过旋转涂布法均匀涂于表面, 其作用像胶水那样黏附石墨烯) , 在300psi 及室温下, 将这种印章按压在石墨上, 高压下印章边缘产生极大的剪应力, 使得石墨烯层从石墨上分离下来。类似地, 将石墨烯层从印章上转移到器件上同样需要固定层0( 要求这种转换层0与石墨烯间的作用力远大于转换层0与石墨烯间的作用力) , 经类the real implementation of the quasi, ruthless. Tough, requirement, carry forward the spirit of a nail, and
3、 the corrective measures The implementation of the nerve endings, do not let the rectification is not in place, not to retreat, the people are not satisfied. Pin four is to adhere to the reform and innovation. To reform the way of thinking and innovative courage to turn style, against four winds, th
4、e courage to face the contradictions, good at solving the chronic ills, dare to break the outdated customs and bad habits Hensha unhealthy tendencies, trees, fresh healthy. The five is to adhere to tackling the problem. That is the wind Su Ji and the education supervision combined, in order to estab
5、lish a new system to promote the normalization of style building, long-term, to enhance the party spirit of honest and pragmatic people thought conscious action. The six is to insist on the completion of the third grasp the overall situation. Activity and end This year the goal of safety production
6、work plan for next year, work together, to promote the activities and the work of production safety with both hands, two promotion, two not mistake. Two, rectification of the overall objectives and specific objectives: (a) the overall path around the four focus, carried out the outstanding problems
7、of the special rectification, the full implementation of the central and provincial Party committee clear the rectification task, effectively curb the four winds, realize the overall improvement of Party and government. The point is: focus on the people, the people, convenience, and resolutely curb
8、the bureaucratic style of work; looking to stimulate grassroots vitality, resolutely curb the Wenshan sea; focus on the cadres honest, clean government, politics, and resolutely curb exceed the standard Quasi occupied office space, Gongjusiyong, public funds, extravagance of the wind; focus on estab
9、lish a correct view of achievements, the concept of power, and resolutely curb acts against the interests of the masses. Accelerate the system reform and construction, improve the people honest and pragmatic normalization system, constantly consolidate and expand educational practice achievements, m
10、ake people satisfied. The recent reform goal: Political Quality Bureau and all Party members and cadres, further improve the quality of the business; the four winds, two problem has been effectively solved. The middle goal of the reform: opposition party and government austerity waste 似的操作使得石墨烯从印章上剥
11、落下来。印章切取转移印制法操作简单, 但难以制备单层石墨烯, Stephen 等 23 通过此方法得到的多为四层的石墨烯( 厚度约为113nm) 。 3.模板法 1988年京谷隆等利用模板法在蒙脱土的层间形成了石墨烯片层，一旦脱除模板，这些片层就会白组装形成体相石墨 。一些研究小组正在探索如何利用二维模板的孔隙制备可自由存在的单层石墨烯片层，但至今尚无令人满意的结果报道。 化学方法: 1.氧化-还原法 指将天然石墨与强酸和强氧化性物质反应生成氧化石墨( GO) ,经过超声分散制备成氧化石墨烯(单层氧化石墨) ,加入还原剂去除氧化石墨表面的含氧基团,如羧基、环氧基和羟基,得到石墨烯。 2.溶液剥
12、离法 原理是将少量的石墨分散于溶剂中,形成低浓度的分散液,利用超声波的作用破坏石墨层间的范德华力,此时溶剂可以插入石墨层间,进行层层剥离,制备出石墨烯。 3.加热Si-C法 加热单晶6H-SiC脱除Si，在单晶(0001) 面上分解出石墨烯片层。具体过程是:将经氧气刻蚀的样品在高真空下通过电子轰击，除去氧化物。用俄歇电子能谱确定表面的氧化物完全被移除后，将样品加热使之温度升高至1250-1450?后恒温1min-20min，从而形成极薄the real implementation of the quasi, ruthless. Tough, requirement, carry forwar
13、d the spirit of a nail, and the corrective measures The implementation of the nerve endings, do not let the rectification is not in place, not to retreat, the people are not satisfied. Pin four is to adhere to the reform and innovation. To reform the way of thinking and innovative courage to turn st
14、yle, against four winds, the courage to face the contradictions, good at solving the chronic ills, dare to break the outdated customs and bad habits Hensha unhealthy tendencies, trees, fresh healthy. The five is to adhere to tackling the problem. That is the wind Su Ji and the education supervision
15、combined, in order to establish a new system to promote the normalization of style building, long-term, to enhance the party spirit of honest and pragmatic people thought conscious action. The six is to insist on the completion of the third grasp the overall situation. Activity and end This year the
16、 goal of safety production work plan for next year, work together, to promote the activities and the work of production safety with both hands, two promotion, two not mistake. Two, rectification of the overall objectives and specific objectives: (a) the overall path around the four focus, carried ou
17、t the outstanding problems of the special rectification, the full implementation of the central and provincial Party committee clear the rectification task, effectively curb the four winds, realize the overall improvement of Party and government. The point is: focus on the people, the people, conven
18、ience, and resolutely curb the bureaucratic style of work; looking to stimulate grassroots vitality, resolutely curb the Wenshan sea; focus on the cadres honest, clean government, politics, and resolutely curb exceed the standard Quasi occupied office space, Gongjusiyong, public funds, extravagance
19、of the wind; focus on establish a correct view of achievements, the concept of power, and resolutely curb acts against the interests of the masses. Accelerate the system reform and construction, improve the people honest and pragmatic normalization system, constantly consolidate and expand education
20、al practice achievements, make people satisfied. The recent reform goal: Political Quality Bureau and all Party members and cadres, further improve the quality of the business; the four winds, two problem has been effectively solved. The middle goal of the reform: opposition party and government aus
21、terity waste 的石墨层,从而制备出单层或是多层石墨烯。 4.化学气相沉积法 使用的是一种以镍为基片的管状简易沉积炉,通入含碳气体,例如,碳氢化合物,它在高温下分解成碳原子沉积在镍的表面,形成石墨烯,通过轻微的化学刻蚀,使石墨烯薄膜和镍片分离得到石墨烯薄膜。 5.氧化分散还原法( 含氧化修饰还原法) 这是目前应用最广泛的合成方法。它是将石墨氧化得到溶液中分散( 借助超声、高速离心) 的石墨烯前体, 再用还原剂还原得到单层或多层石墨烯。常见的氧化方法有Brodie 方法以及Staudenmaier 方法 34 , 其基本原理均为先用强质子酸处理石墨, 形成石墨层间化合物, 然后加入强氧
22、化剂对其进行氧化。其中, Brodie 方法采用发烟硝酸及KClO3 作为氧化剂。Staudenmaier 法用浓硫酸和发烟硝酸混合酸对石墨进行处理, 同样也是以KClO3 为氧化剂。Hummer 方法则使用浓H2SO4、NaNO3 及KMnO4 作氧化剂, Hummer 的实验表明如果得到的氧化石墨烯含氧量比较高时呈现黄色, 低时则呈现黑色。此外, 间氯过氧苯甲酸(MCPBA) 也可以作为氧化剂。以乙醇和钠为原料通过溶剂热法可制备克量级的石墨烯, 不仅产率提高, 而且也解决了以上这种方法所带来的环境污染问题, 符合绿色化学的要求。 三(石墨烯的结构及特性: 结构:石墨烯是碳原子紧密堆积成单层
23、二维蜂窝状晶格结构的一种碳质新材料，厚度只有0.335纳米,仅为头发的20万分之一，是构建其它维数碳质材料(如零维富勒烯、一维纳米碳管、三维石墨)的基本the real implementation of the quasi, ruthless. Tough, requirement, carry forward the spirit of a nail, and the corrective measures The implementation of the nerve endings, do not let the rectification is not in place, not t
24、o retreat, the people are not satisfied. Pin four is to adhere to the reform and innovation. To reform the way of thinking and innovative courage to turn style, against four winds, the courage to face the contradictions, good at solving the chronic ills, dare to break the outdated customs and bad ha
25、bits Hensha unhealthy tendencies, trees, fresh healthy. The five is to adhere to tackling the problem. That is the wind Su Ji and the education supervision combined, in order to establish a new system to promote the normalization of style building, long-term, to enhance the party spirit of honest an
26、d pragmatic people thought conscious action. The six is to insist on the completion of the third grasp the overall situation. Activity and end This year the goal of safety production work plan for next year, work together, to promote the activities and the work of production safety with both hands,
27、two promotion, two not mistake. Two, rectification of the overall objectives and specific objectives: (a) the overall path around the four focus, carried out the outstanding problems of the special rectification, the full implementation of the central and provincial Party committee clear the rectifi
28、cation task, effectively curb the four winds, realize the overall improvement of Party and government. The point is: focus on the people, the people, convenience, and resolutely curb the bureaucratic style of work; looking to stimulate grassroots vitality, resolutely curb the Wenshan sea; focus on t
29、he cadres honest, clean government, politics, and resolutely curb exceed the standard Quasi occupied office space, Gongjusiyong, public funds, extravagance of the wind; focus on establish a correct view of achievements, the concept of power, and resolutely curb acts against the interests of the mass
30、es. Accelerate the system reform and construction, improve the people honest and pragmatic normalization system, constantly consolidate and expand educational practice achievements, make people satisfied. The recent reform goal: Political Quality Bureau and all Party members and cadres, further impr
31、ove the quality of the business; the four winds, two problem has been effectively solved. The middle goal of the reform: opposition party and government austerity waste 单元，具有极好的结晶性、力学性能和电学质量。 完美的石墨烯是二维的, 它只包括六角元胞(等角六边形)。如果有五角元胞和七角元胞存在,那么他们构成石墨烯的缺陷。如果少量的五角元胞细胞会使石墨烯翘曲; 12个五角元胞的会形成富勒烯。碳纳米管也被认为是卷成圆桶的石墨烯
32、。可见，石墨烯是构建其它维数碳质材料(如零维富勒烯、一维纳米碳管、三维石墨)的基本单元。 单原子层石墨晶体薄膜。每个原胞中两个碳原子，每个原子与最相邻三个碳原子形成三个键。每个碳原子贡献一个多余p电子，垂直于graphene平面，形成未成键的电子良好的导电性。 特性:最薄只有一个原子厚 强度最高 美国哥伦比亚大学的专家为了测试石墨烯的强度，先在一块硅晶体板上钻出一些直径一微米的孔，每个小孔上放置一个完好的石墨烯样本，然后用一个带有金刚石探头的工具对样本施加压力。结果显示，在石墨烯样品微粒开始断裂前，每100纳米距离上可承受的最大压力为2(9 微牛左右。按这个结果测算，要使1 米长的石墨烯断裂，需要施加相当于55 牛顿的压力，也就是说，用石墨烯制成的包装袋应该可以承受大约两吨的重量。 没有能隙良好的半导体 良好的导热性 热稳定性优于石墨 优秀导电性电子的运动速度达到了光速的1/300，远远超过了电子在一般导体中的运动速度-电子的“光速”移动碳原子有四the real implementation of the quasi, ruthless. Tough, requirement, carry forward the spirit of a nail, and the corrective measures The implementation of th
