| 碳纳米管薄膜的结构可控制备与应用探索研究 | |
| 李世胜 | |
| Subtype | 博士 |
| Thesis Advisor | 成会明 ; 刘畅 |
| 2012 | |
| Degree Grantor | 中国科学院金属研究所 |
| Place of Conferral | 北京 |
| Degree Discipline | 材料学 |
| Keyword | 碳纳米管 薄膜 制备 结构控制 应用探索 Carbon Nanotube Thin Film Preparation Structure Control Application Exploration |
| Abstract | "碳纳米管是一种具有优异电学、力学、光学和热学性能的一维纳米材料。为使碳纳米管的优异性能在实际应用中得到充分发挥，需对其结构及排列织构等进行有效控制。碳纳米管薄膜是一种多功能性的碳纳米管聚集体，极具应用潜力。本论文以碳纳米管薄膜的结构控制制备为主线，系统研究了碳纳米管的直径、层数、排布方式和导电属性的控制制备方法，并探索了其在电池电极、透明导电薄膜及薄膜晶体管中的可能应用，取得的主要结果如下： 垂直阵列薄膜中碳纳米管的层数和直径控制生长。通过在传统Fe催化剂中引入Pt，制备出二元FePt催化剂。利用FePt催化剂与Al2O3基体间较强的相互作用力，获得了尺寸小、分布窄、面密度高的FePt纳米粒子。通过调节FePt催化剂纳米粒子的大小，高选择性地制备出单壁/双壁碳纳米管垂直阵列薄膜。与Fe催化剂相比，FePt催化生长的碳纳米管垂直阵列具有更高的密度，且碳纳米管的排列有序性好、直径分布窄、热稳定性高。 碳纳米管垂直阵列/石墨烯纸薄膜用于锂离子电池和染料敏化太阳能电池。以柔性导电的石墨烯纸代替传统的硅基体，在其表面直接生长碳纳米管垂直阵列，从而制备出碳纳米管垂直阵列/石墨烯纸薄膜。将该薄膜直接用作锂离子电池的负极材料，无需金属集流体，电极重量减轻近80%，提高了电池的能量密度。锂离子电池性能测试表明该电极具有高的循环稳定性和倍率性能，全碳电极还可提高电池的安全性。将该复合薄膜用于染料敏化太阳能电池，取代价格昂贵、资源日益稀缺的Pt电极，其光电转化效率可达6.05%，为Pt电极的83%，显示了良好的应用前景。 单壁碳纳米管平行阵列薄膜的制备及类蜂窝网络的构建。提出了利用石蜡辅助转移表面生长的单壁碳纳米管平行阵列。在转移过程中，由于单壁碳纳米管间的毛细作用力而在目标基体上自组装形成类蜂窝的二维网络结构。该网络主要是由单壁碳纳米管管束构成，多形成Y型结。与传统透明导电膜中广泛存在的交叉结，即X型结，明显不同。在Y型结中，管间的接触面积大，增加了管间电导，有助于整个二维网络电导的提升。此外，Y型结构成的类蜂窝网络对化学掺杂的响应要比X型结构成的无序网络更高，因而该单壁碳纳米管类蜂窝网络薄膜可用作高灵敏度的化学传感器。 单壁碳纳米管薄膜晶体管的构建及性能优化。提出利用NiO与单壁碳纳米管的低温碳热反应选择性刻蚀金属性单壁碳纳米管，并以留下的半导体性单壁碳纳米管为沟道材料构建薄膜晶体管。通过光刻技术沉积NiO图案，覆盖于单壁碳纳米管薄膜表面进行选择性刻蚀，在与NiO接触的区域中，金属性单壁碳纳米管被刻蚀，留下半导体性单壁碳纳米管，未与NiO接触区域中的单壁碳纳米管仍保持原有结构，并作为源、漏电极，从而构建出全碳纳米管薄膜晶体管。进而利用H2O等离子体高效氧化单壁碳纳米管，在管壁形成C-OH、C=O等功能基团，π电子局域化产生带隙，从而使单壁碳纳米管由金属性向半导体性转变。两种方法获得的薄膜晶体管的开关比都从原始的~2提高到~103，表现出显著的半导体开关特性。" |
| Other Abstract | "Carbon nanotubes (CNTs) are typical one dimensional nanomaterials possessing unique electrical, mechanical, optical and thermal properties. To make a full use of the superb properties of CNTs in applications, it is important to have the structure and texture of CNTs well controlled. A CNT film is a kind of multi-functional structure that has wide-range potential applications. This dissertation focuses on the structure-controlled preparation of CNT films. Control over the diameter, wall-number, quality, transport property, and arrangement of CNTs were investigated. The applications of the CNT films in batteries, transparent conducting films and thin film field effect transistors (FETs) were explored. The main results obtained are listed as follows: Wall-number and diameter controlled growth of vertically aligned CNT (VACNT) array films. By introducing Pt into the traditional Fe catalyst, the interaction between binary FePt catalyst and Al2O3 is found to be much stronger than that of Fe-Al2O3. The strong catalyst-substrate interaction guarantees the formation of high density, ultrafine and uniform FePt nanoparticles even at elevated temperatures. When used as the catalyst for growing VACNTs, the FePt catalyst produced CNTs with good alignment, narrow diameter distribution, and desirable wall-number selectivity. Characterization showed that the vertically-aligned single-walled (SW) and double-walled (DW) CNTs grown from FePt catalyst possess high purity, good homogeneity, and superior thermal stability. The working mechanism of the FePt binary catalyst is discussed in comparison with that of the pure Fe catalyst. Application of VACNT array films as the electrodes of lithium-ion batteries (LIBs) and dye-sensitized solar cells (DSSCs). We prepared VACNTs directly on a graphene paper (GP). The as-prepared freestanding VACNT/GP film was used as an integrated electrode combining both active component and current collector for LIBs, good high-rate capability and cycling performance were demonstrated. When served as the counter electrode of a DSSC, the VACNT/GP film displayed superior overall performance to the GP and slightly lower efficiency than a Pt electrode. Due to its good electrical conductivity, high thermal and chemical stability, and desirable flexibility, the VACNT/GP film may find applications in high-performance, flexible energy storage and conversion devices. Fabrication of SWCNT films with a honeycomb-like network. Honeycomb-like structured SWCNT films were fabricated by using paraffin-mediated transfer printing of horizontally-aligned SWCNT arrays. Instead of cross-junctions (X-junction) that commonly exist in a random SWCNT network, the SWCNTs in a honeycomb-like network mainly form Y-junctions composed of roughly aligned SWCNT bundles. The honeycomb-like structure and bundled SWCNTs dramatically increase the contacting area of adjacent SWCNTs and significantly improve the conductivity of the film. With similar SWCNT density and transparency, the honeycomb-like structured SWCNT films demonstrated lower surface resistance than the random SWCNT network. Chemical doping lead to greater improvement in the conductance of the honeycomb-like SWCNT film. Therefore, the honeycomb-like SWCNT films could be used to assemble gas sensors with high sensitivity. Fabrication and performance optimization of SWCNT thin film FETs. We first proposed and realized selective removal of metallic SWCNTs by using a carbothermic reaction with NiO. When a patterned NiO mask was used, m-SWCNTs contacting with NiO stripes were removed, while semiconducting SWCNTs were retained and served as the channel material. The SWCNTs at the areas free of NiO kept intact and served as the source and drain electrodes. Thus, an all-SWCNT FET was fabricated. By using H2O plasma, the sidewall of SWCNTs were efficiently oxidized by O and OH radicals. Consequently, the π electrons are strongly localized by forming C-OH and C=O groups. Metallic SWCNTs were converted to semiconducting ones due to the opened energy gaps. The SWCNT thin film FETs obtained by these two methods showed dramatically improved current on/off ratios from ~2 to ~103." |
| Document Type | 学位论文 |
| Identifier | http://ir.imr.ac.cn/handle/321006/64454 |
| Collection | 中国科学院金属研究所 |
| Recommended Citation GB/T 7714 | 李世胜. 碳纳米管薄膜的结构可控制备与应用探索研究[D]. 北京. 中国科学院金属研究所,2012. |
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