Coupled process of plastics pyrolysis and chemical vapor deposition for controllable synthesis of vertically aligned carbon nanotube arrays

Efficient conversion of waste plastics into advanced materials is of conspicuous environmental, social and economic benefits. A coupled process of plastic pyrolysis and chemical vapor deposition for vertically aligned carbon nanotube (CNT) array growth was proposed. Various kinds of plastics, such as polypropylene, polyethylene, and polyvinyl chloride, were used as carbon sources for the controllable growth of CNT arrays. The relationship between the length of CNT arrays and the growth time was investigated. It was found that the length of aligned CNTs increased with prolonged growth time. CNT arrays with a length of 500 μm were obtained for a 40-min growth and the average growth rate was estimated to be 12 μm/min. The diameter of CNTs in the arrays can be modulated by controlling the growth temperature and the feeding rate of ferrocene. In addition, substrates with larger specific surface area such as ceramic spheres, quartz fibers, and quartz particles, were adopted to support the growth of CNT arrays. Those results provide strong evidence for the feasibility of conversion from waste plastics into CNT arrays via this reported sustainable materials processing.