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  本文選題：石墨烯　切入點：連續(xù)制備　出處：《江蘇大學》2017年碩士論文　論文類型：學位論文

【摘要】：石墨烯是一種單原子層厚度的新型碳材料,是碳原子以sp2雜化形成的二維蜂窩狀薄膜材料,厚度僅有0.3554nm。石墨烯因為具有優(yōu)異的光、電學性能而被學者們爭相研究。激光的高能特性可以制備出性能優(yōu)異的石墨烯,并且由于激光無污染,操作簡單等獨特的優(yōu)勢,引起越來越多的學者的關(guān)注。目前的研究大多集中在激光在化學氣相沉積法(CVD)中的應(yīng)用,對制備環(huán)境要求較高,工藝復(fù)雜,實現(xiàn)工業(yè)化生產(chǎn)成本較高,因此,有必要探討高效經(jīng)濟的大規(guī)模制備石墨烯的新途徑。本文研究了納秒脈沖激光沖擊水中石墨固體靶材制備石墨烯的新技術(shù),創(chuàng)造性地在石墨靶材兩端設(shè)置兩個銅箔電極,形成水平方向的電場,利用電場力驅(qū)動激光沖擊等離子體運動并沉積在銅箔表面,研究了不同的激光能量和不同的沉積時間對制備效率和質(zhì)量的影響,并且對石墨烯的轉(zhuǎn)移進行了進一步的研究,主要取得了以下創(chuàng)新性研究成果:(1)分析了納秒脈沖激光的作用下石墨烯的生成機理,石墨晶體在極短的時間內(nèi)吸收大量的激光能量,并且受到周圍水介質(zhì)的限制,熱量無法迅速傳輸,在石墨表面形成高溫高壓的等離子體區(qū),從而誘導(dǎo)石墨轉(zhuǎn)變?yōu)槭＾D(zhuǎn)變過程主要可歸納為兩個階段:第一階段為升溫升壓過程,石墨表層碳原子之間的共價鍵斷裂成自由碳原子;第二階段為降溫降壓過程,碳原子之間通過sp2雜化形成石墨烯。(2)探索了不同激光能量和沉積時間對制備的石墨烯質(zhì)量的影響,激光功率密度為1.27x109W/cm2時,僅有極少量的石墨烯沉積在銅箔上,大部分為無定形碳;激光功率密度為2.55x109W/cm2時,隨著沉積時間的增加,石墨烯的產(chǎn)生效率也明顯提高;激光功率密度達到5.10x109W/cm2時,沉積15min發(fā)現(xiàn)得到的石墨烯面積較大,幾乎遍布整個銅箔表面,層數(shù)比較均勻,效率達到40cm2/h,繼續(xù)增加沉積時間會使石墨烯層數(shù)增加,褶皺等缺陷也會增加。(3)研究改進了石墨烯高質(zhì)量轉(zhuǎn)移技術(shù),通過改進RCA清洗技術(shù),將SC-1和SC-2溶液稀釋到20:1:1對硅片進行清洗去除大的顆粒物和有機物,再采用激光空化產(chǎn)生脈動空泡,空泡的脈動運動產(chǎn)生等離子沖擊波和微射流可以去除硅片表面的微納米顆粒,使硅片的親水性得到極大的改善,從而提高了石墨烯的轉(zhuǎn)移質(zhì)量。
[Abstract]:Graphene is a new kind of carbon material with the thickness of monatomic layer. It is a two-dimensional honeycomb film material formed by sp2 hybrid of carbon atom. The thickness of graphene is only 0.3554 nm. The high energy characteristic of laser can produce graphene with excellent performance, and because of its unique advantages, such as no pollution, simple operation and so on, More and more scholars pay more and more attention to it. At present, most of the researches focus on the application of laser in chemical vapor deposition (CVD), which requires high preparation environment, complex process and high cost to realize industrialized production. It is necessary to explore a new way to produce graphene on a high efficient and economical scale. In this paper, a new technique of preparing graphene from graphite solid target in water by nanosecond pulsed laser is studied. Two copper foil electrodes are creatively installed at the two ends of graphite target. A horizontal electric field was formed. The laser impingement plasma was driven by electric field force and deposited on the surface of copper foil. The effects of different laser energy and deposition time on the preparation efficiency and quality were studied. Furthermore, the transfer of graphene was further studied. The following innovative research results were obtained: 1) the formation mechanism of graphene under nanosecond pulse laser was analyzed. The graphite crystal absorbs a large amount of laser energy in a very short time. And limited by the surrounding water medium, the heat can not be transferred rapidly, forming a high temperature and high pressure plasma region on the surface of graphite. The transition process can be divided into two stages: the first stage is the process of temperature and pressure rise, the covalent bond between the carbon atoms in the surface layer of graphite breaks into free carbon atom, and the second stage is the process of decreasing temperature and reducing pressure. The effect of different laser energy and deposition time on the quality of graphene was investigated by sp2 hybridization between carbon atoms. When the laser power density was 1.27x109W/cm2, only a small amount of graphene was deposited on copper foil. When the laser power density is 2.55x109W/cm2, the yield efficiency of graphene increases obviously with the increase of deposition time, and when the laser power density reaches 5.10x109W/cm2, the area of graphene obtained by 15min deposition is larger. Almost all over the surface of copper foil, the number of layers is relatively uniform, and the efficiency is up to 40 cm 2 / h. If the deposition time continues to increase, the number of graphene layers will increase, and the defects such as folds will also increase.) the high quality transfer technology of graphene has been studied and improved. By improving the RCA cleaning technology, The SC-1 and SC-2 solution was diluted to 20:1:1 to remove the large particles and organic matter, then the pulsating cavitation was produced by laser cavitation. The plasma shock wave and micro-jet generated by the pulsating movement of the cavitation could remove the microparticles on the surface of the silicon wafer. The hydrophilicity of silicon wafer was greatly improved and the transfer quality of graphene was improved.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ127.11

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本文編號：1650894