(a)
(b)
(c)
(d)
(e)
Figure 4: Point defects of graphene structure ((a)–(d)). (a) Stone-Wales defect SW(5-7-7-5). (b) Single vacancy defect V1(5-9). (c) Double vacancy defect V2(5-8-5). (d) Double vacancy defect V2(555-777). (e) Double vacancy defect V2(5555-6-7777) formed from (c). Reprinted from [46].