Synthesis Of Carbon Nanotubes By Chemical Vapor Deposition Using Catalyst Derived From Layered Double Hydroxides

Since the discovery of carbon nanotubes (CNTs) by Iijima in 1991, CNTs have attracted much attention due to their scientific significance and potential technological applications. Meanwhile, CNT materials become the frontier of scientific field such as physics, chemistry and material. Chemical vapor deposition (CVD) becomes the main method of CNT preparation for its simple reactor, low cost and controlled reaction. But there are also some disadvantages in the CVD method, such as low purity and yield of the products. So to prepare catalyst with high activity is very important in the process of CNT synthesis by CVD. In this paper we used LDHs as catalyst precursor to prepare CNTs by CVD.The details are as follows:1. Preparation of N-doped CNTs using Co/Al LDHs as catalyst precursorCo/Al LDHs with layered structure were prepared by homogeneous precipitation method. After calcination at 500 oC, the obtained products were used as catalyst to synthesize N-doped CNTs by CVD with methane and acetonitrile as carbon and nitrogen source. By a series of characterlization of the products, we found N-doped CNTs with good morphology and purity were obtained when the gas flow rate (mL min-1) were at 30:30. Also the yield of N-doped CNTs was largest at this flow rate.2. Preparation of CNTs using Co/Al/La LDHs as catalyst precursorCo/Al/La LDHs with different La content were prepared by co-precipitation method. After the procedure of calcination at 600 oC, the products were used as catalyst to synthesize CNTs by CVD with acetylene as carbon source. We studied the effect of La content in the catalyst precursor on the preparation of CNTs by CVD. Finally we found that the obtained CNTs had good quality and quantity when the La content was at 5%.3. Effects of different experimental parameters on the preparation of CNTs by CVDIn our work, several factors such as calcination temperature, growth temperature, growth time and flow rate, were studied to find out the influence on the products. Meanwhile, we confirmed optimum experimental parameters by a series of contrast experiments.