The release of free standing vertically-aligned carbon nanotube arrays from a substrate using CO2 oxidation Original Research Article

Free standing vertically-aligned carbon nanotube (CNT) arrays were released from a quartz substrate on a large scale by using CO2 as an oxidative reagent to weaken the array–substrate interaction and facilitate their harvest. During the oxidation process, amorphous carbon and carbon in contact with metallic particles were preferentially etched, leading to the easy release of high quality free standing CNT arrays. O2 was also used as an oxidant for comparison. The O2 showed a stronger oxidizability and caused the formation of CNTs with a turbostratic–graphitic carbon heterojunction structure. The mechanisms of CO2 and O2 oxidation of CNT arrays were investigated, and based on these results, CO2 was considered a more suitable oxidant for the purpose.