Atom at edge of graphene is different from atom in bulk lattice while studying about Graphene structure so I want to ask why this is so? I really appreciate if some one give me answer.
The physical origin is the edge atoms are not fully coordinated as bulk atoms. Bulk graphene atoms in sp2 hybridization and have three neighbors, but edge atoms have only two neighbors, (dangling bond if one neighbor) thus the electronic, chemical and mechanical properties are all different. For mechanical part, it will cause ''edge stress'', and this effect not only happens to graphene but almost all materials which is sometimes called 'surface effect'. For graphene and MoS2 edge stress: http://prb.aps.org/abstract/PRB/v78/i7/e073405, http://scitation.aip.org/content/aip/journal/jap/114/16/10.1063/1.4826905
very interesting question mr.Tayyab. From my knowledge it is right, the carbon atoms at the edge is different from the bulk, it may be the hybradization difference, the preparation method also very important factor in this nature. i tried to functionalize the reduced graphene oxide (graphene), followed by the Ag nanowire growth on the surface of graphene, but the functionalization happed only at the corners of the graphene and the wire formed only at the corner of the sheets.
Agreed with p.Ganaprakasm Sir: at the edge there may be two single bonds or may be double bond with atom and in the case of atoms in bulk lattice sp2 hybridization which means that there must be two single bond and one double bond ,attached to 3 carbon atoms.
The physical origin is the edge atoms are not fully coordinated as bulk atoms. Bulk graphene atoms in sp2 hybridization and have three neighbors, but edge atoms have only two neighbors, (dangling bond if one neighbor) thus the electronic, chemical and mechanical properties are all different. For mechanical part, it will cause ''edge stress'', and this effect not only happens to graphene but almost all materials which is sometimes called 'surface effect'. For graphene and MoS2 edge stress: http://prb.aps.org/abstract/PRB/v78/i7/e073405, http://scitation.aip.org/content/aip/journal/jap/114/16/10.1063/1.4826905