Interplay between nitrogen dopants and native point defects in graphene

• Published in: Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2012-04, Vol.85 (16), Article 165439
• Main Authors: Hou, Zhufeng, Wang, Xianlong, Ikeda, Takashi, Terakura, Kiyoyuki, Oshima, Masaharu, Kakimoto, Masa-aki, Miyata, Seizo
• Format: Article
• Language: English
• Subjects: Agglomeration; Carbon; Condensed matter; Defects; Dopants; Doping; Graphene; Point defects; Stability
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.85.165439

To understand the interaction between nitrogen dopants and native point defects in graphene, we have studied the energetic stability of N-doped graphene with vacancies and Stone-Wales (SW) defect by performing the density functional theory calculations. Our results show that N substitution energetically prefers to occur at the carbon atoms near the defects, especially for those sites with larger bond shortening, indicating that the defect-induced strain plays an important role in the stability of N dopants in defective graphene. In the presence of monovacancy, the most stable position for N dopant is the pyridinelike configuration, while for other point defects studied (SW defect and divacancies) N prefers a site in the pentagonal ring. The effect of native point defects on N dopants is quite strong: While the N doping is endothermic in defect-free graphene, it becomes exothermic for defective graphene. Our results imply that the native point defect and N dopant attract each other, i.e., cooperative effect, which means that substitutional N dopants would increase the probability of point defect generation and vice versa. Our findings are supported by recent experimental studies on the N doping of graphene. Furthermore we point out possibilities of aggregation of multiple N dopants near native point defects. Finally we make brief comments on the effect of Fe adsorption on the stability of N dopant aggregation.