Combustion Synthesis of Carbon Nanostructures Using Rotating Counterflow Diffusion Flames

Introduction A hydrocarbon flame can naturally and readily provide an appropriate high-temperature environment with abundant radical concentrations required for the growth of carbon nanotubes (CNTs) [1] or carbon nano-onions (CNOs) [2]. Therefore, flame synthesis shows a more promising potential for inexpensive and mass production of high-purity carbon nanostructures than other synthesis methods do. Recently, great efforts have been devoted to studying flame synthesis of CNTs. As described in our previous studies [3] rotating flow significantly affected the temperature distribution, mixing of fuel and oxidizer, and residence time of the flow, which in turn were expected to affect greatly the hydrocarbon reactants and environments for the formation of CNTs. However, rotating flow fields have not been applied to control growth of CNOs in flames prior to this study. Therefore, in this paper we aim at exploring the influence of flow rotation on the synthesis of carbon nanomaterials using rotating counterflow diffusion flames and a catalytic Ni substrate.