Nitrogen-doped graphene has been of recent interest to manipulate the properties of graphene. Many studies revealed that heteroatom doping with graphene is one of the efficient approaches for tuning its electronic and chemical properties. In this study, we considered the finite-sized graphene model, C<sub>186</sub>H<sub>36</sub> to investigate the double nitrogen doping within six-membered rings of the graphene. Three possibilities of dinitrogen doping are 1,2-, 1,3- and 1,4-substitutions. Our systematic study presents the results of positional preference of double nitrogen doping involving multiple non-equivalent six-membered rings. Our aim is to investigate the positional preference of three different doping possibilities and the selectivity of rings for doping of two nitrogen atoms. All structures were optimized using density functional theory (DFT) B3LYP/6-31G(d) level. HOMO-LUMO energy gap values for all the positional isomers were calculated using TPSSh/6-31G(d)//B3LYP/6-31G(d) level. All the calculations were performed using Gaussian 16 program package. The relative stabilities of these isomers are found to follow the trend in majority of six-membered rings: 1,4- &gt; 1,3- &gt; 1,2-substitution. Interestingly, the stabilities of double nitrogen dopants in all three types of substitutions depend on the doping location. Our computational study predicts that the most stable isomers have two nitrogen atoms doped close to the zigzag edge. However, the nitrogen doping at the armchair edge provides the structures with high relative energies. We have analyzed the effect of nitrogen dopants in graphene on HOMO and LUMO energies and HOMO-LUMO energy gaps.

Computational exploration of double nitrogen doping of 1,2-, 1,3- and 1,4- substitutions in multiple rings of graphene

256th National Meeting (2018)

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