Plasma‐Induced Damage and Surface Functionalization of Double‐Walled Carbon Nanotubes Using Atmospheric Pressure RF Discharge

Double‐walled carbon nanotubes (DWCNTs) were synthesized using atmospheric pressure plasma‐enhanced chemical vapor deposition. As‐produced DWCNTs were exposed to He/H2 atmospheric pressure RF discharge for 1 min at 100 °C. The top CNT layer was severely damaged, showing a large D‐band peak in the Raman spectrum. However, hydrogen plasma treatment does not create covalent CH bonds. When a H2/O2 mixture was added, plasma damage was suppressed greatly because O2 scavenges active hydrogen. The CH groups were produced via oxygen‐containing reactive species. Active hydrogen creates sp3‐like carbon structures that destroy graphitized CNTs. Oxygen‐containing species such as OH and HOO are useful to break sp2 bonds and to functionalize CNT sidewalls. magnified image