本實驗利用熱化學氣相沈積法，於高溫下通入乙烯作為碳源生長 奈米碳管。我們將奈米鎳粉體加入乙醇中，利用浸泡法和液滴法塗佈 催化劑於基板上。基板主要分兩類：(1)親水性矽奈米草(2)疏水性矽 奈米草。同時藉由改變催化劑溶液的化學性質、生長溫度、氫氣流量 來觀察奈米碳管的生長情形。接著把奈米碳管鍍上白金後，發現其表 面性質接近超疏水。 實驗結果發現，利用浸泡法於親水性矽奈米草上生長奈米碳管， 會使奈米粉體聚集，生長出管徑粗細不均的奈米碳管。我們將溶液加 入醋酸鉬，發現能使奈米粉體分散，生長出管徑較細的奈米碳管，但 也會形成較多的無晶形碳化合物。使用浸泡法於疏水性矽奈米上生長 奈米碳管，浸泡溶液的表面能大小會影響奈米碳管的生長與否，用乙 醇作為溶液能生長出奈米碳管，用水則量非常少。利用液滴法於疏水 性矽奈米草上生長奈米碳管，比一般的矽基板生長較小區域的奈米碳 管，且碳管的管徑分佈較不均勻。 此外，我們發展了一種不添加金屬催化劑，利用熱化學氣相沈積 生長奈米碳管的方法。將矽奈米草表面沈積一層PTFE薄膜，再將矽奈米草利用熱化學氣相沈積法，於750 ℃下可生長出大量的多壁奈米碳管。 We used a thermal CVD with C2H4 carbon sources to grow CNTs at high temperature. Nickel nanoparticles were used as the catalyst, which can be held in water or ethanol solution, and then spread on a substrate by using dip-coating and drop-coating methods. The substrates include hydrophilic and hydrophobic nanograss. The parameters of solution Chemical property, growth temperature, and hydrogen flow rate were controlled to investigate the CNT morphology. The results show that using dip-coating method to grow CNTs on the hydrophilic nanograss will make nanoparticles aggregation and lead to the variations in CNT diameter. The nanoparticles can be dispersed as molybdenum (Ⅱ) acetate was dissolved into the solution, which will grow CNTs with smaller diameter, but the amount of amorphous carbon compound will be greater also. The CNT surface can be transferred to a superhydrophobic state as we deposited Pt film on it. The surface energy of solution will affect the amount of CNTs when we use a dip-coating method to grow CNTs on the hydrophobic nanograss. The amount of CNTs is greater by ethanol than by water.In addition, using drop-coating method to grow CNTs on the hydrophobic nanograss will make smaller area and wider distribution of CNT diameters than on the silicon wafer. More interesting, a lot of CNTs were grown at 750 ℃ by depositing a PTFE (polytetrafluoroethylene) film on the hydrophilic nanograss and treating it in the thermal CVD, which demonstrates that we have developed a method to grow CNTs without metal catalyst.
