Controlled Synthesis of Nitrogen-Doped Graphene from a Heteroatom Polymer and Its Mechanism of Formation

Heteroatom polymeric precursor with an aromatic substituent (polyurethane acrylate) was designed and found to generate nitrogen-doped graphene at 1000 degrees C. Upon thermal degradation, a nitrogenous fragment was liberated in situ. As a consequence, nitrogen-doped graphene was formed in a single step. Further, this methodology was extended for studying the effect of annealing nonheteroatom polymer with an aromatic substituent (styrene butadiene random copolymer) under similar conditions. The isolated product demonstrated undoped graphene-like structure. The mechanism of nitrogen-doped graphitization was studied by annealing different heteroatom polymer units with an aliphatic and aromatic framework in a chemical vapor deposition reactor. The effect of precursor heteroatom polymer structure and annealing temperature in the presence of copper catalyst on the efficacy of formation of nitrogen-doped graphene was examined. The nitrogen-doped graphene exhibited semiconducting behavior over semimetallic behavior of the undoped graphene. Moreover, the nitrogen-doped graphene displayed better electrochemical properties compared to the undoped variety. These advances in the synthesis of graphitic structures can be readily extended for the fabrication of many advanced materials with controlled structure and properties.