Examining the stability of folded graphene edges against electron beam induced sputtering with atomic resolution

Low energy electron beam irradiation of the edges of graphene can lead to rearrangement of the carbon atomic structure. We demonstrate the ability to distinguish intrinsic edges of graphene from edges formed by back folding based upon atomic structure and their susceptibility to sputtering. We examine how the atomic structure of the edges of graphene and few layer graphene sheets influences their stability under electron beam irradiation at a low electron accelerating voltage of 80 kV using aberration-corrected high-resolution transmission electron microscopy. We demonstrate that edges of few layer graphene produced by back folding are extremely robust against electron beam induced sputtering as compared to intrinsic edges that are naturally formed. The stability of the folded edges in few layer graphene is shown to increase with increasing number of layers. The higher stability of fold edges is related to the absence of any unsaturated carbon atoms that can be sputtered by electron beam irradiation.