電解剝落法之石墨表面性質探討;Surface Properties of Graphiteby Electrolytic Exfoliation

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/53677

Title:	電解剝落法之石墨表面性質探討;Surface Properties of Graphiteby Electrolytic Exfoliation
Authors:	蕭慕柔;Hsiao,Mu-Jou
Contributors:	化學工程與材料工程研究所
Keywords:	電解剝落法;石墨烯;石墨;潤濕現象;超疏水;electrolytic exfoliation;graphene;wetting phenomena;superhydrophobic;graphite
Date:	2012-06-14
Issue Date:	2012-09-11 18:10:47 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文首先將探討以電解法製備石墨烯之機制，一方面將研究石墨電極表面性質，包括：物理粗糙度、潤濕現象、導電性及化學組成，進而發現陽極石墨表面在電解過程中會與氧氣反應形成一層氧化石墨，故我們推斷所剝落的粒子應為氧化石墨，並且我們可進一步改變電解時間及輸出電流以控制石墨表面的氧化程度；另一方面將針對電解所剝落的石墨粒子進行分析，包括：遮蔽效應、粒徑分析、表面電位、UV及TGA，發現電解剝落的氧化石墨相較於一般以Hummer method製備的氧化石墨其氧化程度較低，並且我們可進一步改變電解液的pH值以控制奈米石墨粒子表面的氧化程度。　　本論文的第二部分將探討超疏水石墨表面的潤濕行為，我們利用簡易的物理方式製備了超疏水石墨表面，首先以膠帶剝離石墨表面，即製出高疏水狀態，再將此石墨片進行超音波震盪，即製出超疏水之石墨表面，我們認為其形成原因為表面粗糙度，在經膠帶的機械力剝離後，石墨表面產生了微米級的粗糙度，再經過超音波震盪後，於溶液中可明顯觀察到有微小粒子從石墨片剝落，而此粒子經過粒徑分析測得為奈米等級粒子，故推斷經震盪後與微米級結構上產生了奈米級的粗糙度，而另一方面，我們於超疏水石墨表面觀察到Ostwald ripening的現象，此現象於疏水表面則不會發生，故此亦可證實我們的推論；此外，由於疏水及超疏水的表面結構不同，對於水潤濕於粗糙孔隙的行為便有所差異，故展現了不同的遲滯行為；最後，我們亦觀察到此超疏水石墨表面對於水的黏滯力，會隨接觸時間而增強，直至2 min可達到最大而持平。In this thesis, the mechanism of fabricated graphene by electrolytic exfoliation is investigated. The experiment is divided into three parts. In the first part, we discuss the surface properties of graphite electrode through physical roughness, wetting phenomena, surface conductivity, and chemical composition. The anodic graphite surface react with oxygen then form a graphite oxide layer during electrolytic exfoliation. Therefore, we infer that the particles which are exfoliated from the surface of anode are graphite oxide. Furthermore, we can control the contact angle of graphite surface by electrolysis.In the second part, we analyze the surface properties of exfoliated graphite oxide particles through particle size, zeta potential, UV-Vis spectrophotometer, and Thermogravimetric analysis. In these results, we observed that the oxidation order of graphite oxide nanoparticles by Electrolytic exfoliation is lower than that by Hummer method. Furthermore, we can control oxidation order of graphite oxide nanoparticles by tuning the pH of electrolyte.In the third part, we discuss the wetting behavior of graphite surface. A superhydrophobic graphite surface has been fabricated through two facile physical steps, peeling and ultrasonicating. Peeling yields micron-scale roughening, and thus a highly hydrophobic surface is obtained. Further ultrasonicating results in a superhydrophobic surface with nanostructure embedded in microstructure. The nanostructure leads to networklike pores on the superhydrophobic film and convective Ostwald ripening is observed. Owing to their distinct resistance to liquid imbibition, contact angle hysteresis on hydrophobic and superhydrophobic surfaces is fundamentally different. Moreover, the adhesive force on a superhydrophobic surface grows with the contact time, and such aging effect is absent on hydrophobic graphite surface.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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