The influence of source molecule structure on the low temperature growth of nitrogen-doped graphene

Doping of heteroatoms such as nitrogen into the lattice structure of graphene can tune and tailor the overall electronic properties. N-doped graphene, depending on the nitrogen bonding mode and/or bonding configuration, displays subtly altered properties in comparison to pristine graphene. However, there remains a disappointing shortage of reliable methods for introducing dopants in a controlled and reproducible manner, preventing a thorough understanding of the relationship between structure and properties. In this study we aimed to prepare graphenes with nitrogen atoms doped at a graphitic (quaternary) site by depositing a source molecule containing a graphitic nitrogen atom: 4,4,8,8,12,12-hexamethyl-8,12-dihydro-4H-benzo[9,1]quinolizino[3,4,5,6,7-defg]acridine or 4H-benzo[9,1]quinolizino[3,4,5,6,7-defg]acridine-4,8,12-trione, on a heated Pt(111) substrate. At 400°C, graphene with nitrogen atoms exclusively doped at a graphitic site was synthesized from the former molecule, while not from the latter molecule at any temperature. The present result indicates that the rational design of a source molecule is quite important for controlling the nitrogen doped site in the graphene lattice.