Value-added utilization of pyrolysis heavy distillate for the synthesis of nitrogen doped graphene with chemical vapor deposition

Abstract

The synthesis of graphene and nitrogen doped graphene (NG) with inexpensive pyrolysis heavy distillate (PHD) as a carbon source and urea as a nitrogen source by chemical vapor deposition on a copper substrate under hydrogen flow has been studied. The variables in synthesis were process temperature and hydrogen flow rate. The PHD is rich in aromatic compounds. These cyclic structured molecules resemble the basic unit of graphene and there is no need to break C-C atomic bonds and allows for graphene synthesis at a lower temperature. The morphology and properties of synthesized graphene and NG were characterized by Raman spectroscopy, TEM, XRD, BET and XPS. Results indicated that the increasing hydrogen flow rate and decreasing growth temperature, increase defects in the graphene, which are favorable for the catalyst support applications. From the Raman and XRD analysis, the NG and graphene derived from these carbon sources are few layers. The average nitrogen content was 5.89% in the structure of NG with three different types of nitrogen atoms namely; pyridinic (32.03%), pyrrolic (51.70%) and graphitic (16.97%). The defects are mainly of vacancy type because pyridinic nitrogen creates vacancies in the structure of graphene. We believe that these results will play an important role in the utilization of inexpensive carbon sources to convert high value added materials.