Nitrogen doping induced by intrinsic defects of recycled polyethylene terephthalate‐derived carbon nanotubes

Abstract The indiscriminate utilization of nondegradable polyethylene terephthalate (PET)‐based products has triggered serious environmental pollution that has to be resolved vigorously. A simple synthesis of N‐doped carbon nanotubes from recycled PET (NCNTs r‐PET ) was developed by a nitric acid‐assisted hydrothermal method. Experimental results and theoretical calculations show that the intrinsic defects in CNTs r‐PET would induce N‐doping by NH 3 generated from nitric acid during the hydrothermal process, thus producing the NCNTs r‐PET . The life cycle assessment proves that the developed method for N‐doped CNTs using r‐PET as the carbon source is more environmentally friendly than the conventional chemical vapor deposition using acetylene as the carbon source. As a typical application, the NCNTs r‐PET delivered an impressive sodium storage capacity with an ultralong lifespan. This work not only provides a new route to upcycling waste plastics into valuable carbonaceous materials in an ecofriendly manner, but also reveals a basic understanding of the N‐doping mechanism in carbonaceous materials.