▎ 摘　　要

The stability of material structure is the key factor to determine its service capacity and lifetime. The structure evolution of vertical few-layer graphene (FLG) under high electric field was directly observed in situ TEM. The structure stability of FLG depends on its crystallinity and edge morphology. The vertical FLG without pinhole defects can sustain an electrostatic field beyond 58.5 V/nm. The vertical FLG with pinhole defects disintegrated from top to bottom due to field evaporation and the critical electrostatic field weaken to 17.4 V/nm. The vertical FLG with curly layer perpendicular to the electric field stretched and slid at the edge due to the layer sliding and the critical fracture electrostatic field of it was low to 7.5 V/nm which is an order of magnitudes small than that of the curly layer parallel to the electrostatic field of 24.7 V/nm. Those results were the first direct observation of the nano-structure evolution of FLG under high electric field. It helps to understand the deterioration mechanism of FLG under high electric field in free space and provides guidance for the high electric field applications such as field electron emitter and scanning tunneling microscopy. (C) 2018 Elsevier Ltd. All rights reserved.