In Situ Growth Of Carbon Nano-materials On Copper Substrates By Chemical Vapor Deposition

Recently, carbon nanomaterials, such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs), have been very widely used in the fields of novel composites and electronic devices with high performance, for example, the electrical contact materials, super-capacitors and absorbing materials, due to their excellent physical and mechanical properties. For such applications, a good conductivity between carbon nanomaterials and metal substrates is required. Direct growth of carbon nanomaterials by chemical vapour deposition (CVD) on metal substrate is an obvious effective way to obtain good interface between carbon nanomaterials and substrate with lowest contact resistance.Herein, carbon nanomaterials were grown directly on copper powders by CVD using catalysts (Fe/Y, Ni/Y and Co), prepared by deposition–precipitation. The effects of the content and reduction temperatures of catalyst, growth temperatures and composition ratio of the mixed reaction gas on the sturcture and morphology of the as-obtained carbon nanomaterials were investigated. Furthermore, we also systematically investigeted the carbon nanomaterial growth directly on bulk copper substrate (copper plate) for the need to use as electrical contact switch. The optimum praperation conditions and growth mechanism of helical CNFs was explored.The results show that: 1) the main products were carbon onions at various conditions using Fe as the catalyst. Only a few of CNTs was obtained when the Fe catalyst with 10wt% (based on copper powers) was reduced at 600℃. CNTs with relative high purity were synthesized using Ni/Y catalyst at 600℃for one hour. The yield of the carbon products first increased and then reduced with increasing the catalyst content. When the catalyst content was about 5wt%, the yield of the product reached the peak. 2) Co is an effective catalyst for carbon nano-material growth directly on Cu powders, without any additves as stabilizer. CNTs with uniform diameters and bamboo-shape structures were obtained using 3wt% Co catalyst at 600℃with acetylene as carbon source (carbon source and carrier gas ratio is 1:16). It was found that a few of Cu nanoparticles was also acted as catalyst. Furthermore, a certain amount of Co content is necessary to enhance the catalytic activity of Cu. 3) for the copper plate with Co as a catalyst, the optimum growth conditions for CNTs with uniform diamaters and bamboo-shape structures was as follow : the solution concentration for the catalyst preparation was 0.01mol/L, and the growth temperature was 800℃. Single and double helical carbon nanofibers with high purity and quality were synthesized using Ni/Y catalyst (catalyst solution concentration is 0.01-0.05mol/L) at 800℃. 4) The growth mechanism of single and double helical CNFs follow the theory of "catalytic activity anisotropy of the catalyst particle ".