本文選題：碳納米管 + 固相碳源��； 參考：《北京化工大學(xué)》2015年碩士論文

【摘要】：碳納米管作為一維炭材料的典型代表,因其獨(dú)特的電磁、力學(xué)、熱學(xué)、光學(xué)等性能,在納米電子器件、復(fù)合材料、生物醫(yī)療、儲(chǔ)氫材料等領(lǐng)域被廣泛研究。經(jīng)過多年的發(fā)展,在制備方法、生長機(jī)理以及應(yīng)用領(lǐng)域等方面取得了巨大的成果,被譽(yù)為21世紀(jì)最有前途的材料之一,但目前還沒有一種方法能夠制備出結(jié)構(gòu)規(guī)整、純度高、層數(shù)可控的碳納米管,因此在結(jié)合現(xiàn)有的制備方法的基礎(chǔ)上,提出新的制備工藝是一種可行的途徑。本文利用固相碳源與催化劑混合、炭化,并在助催化劑的作用下,合成多壁碳納米管。采用SEM、TEM、HRTEM、XRD、Raman等分析表征手段研究碳管的形貌結(jié)構(gòu)。結(jié)果發(fā)現(xiàn)用該方法制得的碳納米管直徑為50～100nm,長度為0.2～4μm,管壁較薄,直線型,結(jié)晶性能較好以及內(nèi)部有較高催化劑填充率。在實(shí)驗(yàn)過程中,通過改變碳源的種類和顆粒大小、催化劑的類型及與碳源混合方式、酸化時(shí)間、反應(yīng)溫度、保溫時(shí)間以及H2O和噻吩(C4H4S)添加量等參數(shù),最終獲得了碳管的最佳合成條件：選擇利用10～20μm的天然石墨通過改性的H法氧化24h得到的氧化石墨烯為碳源,NiO/MgO為催化劑,按照質(zhì)量比3：10的比例,在乙醇溶液中混合均勻并加熱蒸干,在850℃炭化,保溫6～10h,并同時(shí)通入1.5ppm·min-1的水蒸氣和1ppm·min-1的噻吩,最終得到形貌較好的CNTs。通過對實(shí)驗(yàn)結(jié)果分析,提出一種新的制備CNTs的生長機(jī)理,其過程如下：(1)氧化處理使得碳源表面含有大量官能團(tuán)和活性較高的碳位點(diǎn),可以均勻吸附和錨合催化劑顆粒；(2)在炭化過程中,催化劑被還原,同時(shí)吸附S原子使其熔點(diǎn)降低,在Ostwald熟化作用下相互融并；(3)催化劑顆粒刻蝕碳層并吸附、溶解碳原子簇,使催化劑中碳的濃度升高；(4)當(dāng)碳濃度增大到一定量時(shí),在催化劑表面析出碳層,繼續(xù)吸附S和刻蝕碳源,使得催化劑體內(nèi)壓力增大,在膨脹作用力下,催化劑變形拉長；(5)隨著吸附S原子的飽和以及碳源的耗盡,生長結(jié)束,最后形成碳包覆金屬硫化物的碳納米管。本實(shí)驗(yàn)制得的CNTs作為鋰離子二次電池負(fù)極材料具有較高的比容量和循環(huán)穩(wěn)定性。在小電流密度50mA·g-1下,首次放電比容量達(dá)到957.3 mAh·g-1,循環(huán)50次后仍保持600mAh·g-1左右。通過前三次充放電電容量-電壓曲線以及循環(huán)伏安曲線分析得出,填充在碳納米管中的金屬硫化物有較高比容量,在今后實(shí)驗(yàn)中,適量的保留填充在CNTs中的金屬硫化物可以有效地提高材料的儲(chǔ)鋰性能。
[Abstract]:As a typical representative of one-dimensional carbon materials, carbon nanotubes (CNTs) have been widely studied in the fields of nano-electronic devices, composite materials, biomedical materials and hydrogen storage materials because of their unique electromagnetic, mechanical, thermal and optical properties. After years of development, great achievements have been made in preparation methods, growth mechanisms and application fields, which are regarded as one of the most promising materials in the 21st century. Because of the controllable layers of carbon nanotubes, it is feasible to propose a new preparation process based on the existing preparation methods. In this paper, multi-walled carbon nanotubes (MCNTs) were synthesized from solid carbon source and catalyst by carbonization and co-catalyst. The morphology and structure of carbon tubes were studied by means of Raman analysis and Raman analysis. The results show that the diameter and length of carbon nanotubes prepared by this method are 50 ~ 100 nm and 0.2 渭 m respectively. The tubes have thin wall, linear shape, good crystallinity and high filling rate of catalyst. During the experiment, by changing the kinds and particle size of carbon source, the type of catalyst and its mixing mode with carbon source, acidizing time, reaction temperature, holding time and adding amount of H _ 2O and thiophene C _ 4H _ 4S, etc. Finally, the optimum synthesis conditions of carbon tube were obtained: the graphene oxide obtained by oxidation of 10 ~ 20 渭 m natural graphite for 24 h by modified H method was used as the catalyst of nio / MgO, and the mass ratio of nio / MgO was 3:10. After mixed in ethanol solution and heated and evaporated, carbonized at 850 鈩，

本文編號：1819996