Controllable and Large-Scale Synthesis of Carbon Nanofibers, Bamboo-Like Nanotubes, and Chains of Nanospheres over Fe/SnO₂ and Their Microwave-Absorption Properties

Carbon nanofibers (CNFs), bamboo-like carbon nanotubes (CNTs), and chains of carbon nanospheres (CNSs) were produced selectively in large quantities in the pyrolysis of acetylene at 500, 600, and 700 °C, respectively, over Fe/SnO 2 nanoparticles generated by means of a combined sol−gel and hydrogen-reduction method. One advantage of this approach is that there is no need of using a dilute gas such as argon or nitrogen. It is found that the pyrolysis temperature has considerable effect on the yield, morphology, and microwave-absorption properties of the obtained materials. The corresponding yields of CNFs, bamboo-like CNTs, and chains of CNSs are high, up to 25595, 36791, and 37039%, respectively. Thus, a simple and environment-friendly approach has been proposed for mass production of CNFs, bamboo-like CNTs, and chain of CNSs in a controllable manner. In addition, the as-prepared carbon materials are demonstrated to show good microwave-absorption properties. On the basis of the results, we propose a possible formation mechanism.