▎ 摘　　要

A comprehensive study on electrostatic potential properties of edge-functionalized graphene under an external electric field was performed by using the density functional theory. The shapes and attached functional groups of the edges cause substantial variation of their electrostatic potential outside the edges. Our calculations reveal that graphene edges functionalized by H, OH, and COOH cause relatively large emission current for a wide range of the electric field due to the decrease in the potential barriers caused by the dipoles compared to that before functionalization, while an O termination substantially suppresses the current by increasing the potential barrier. In addition, the NH group increases and decreases the field emission current from zigzag and armchair edges, respectively, because of the different electrostatic environment around the edge atomic sites arising from the NH group conformations. (C) 2018 Elsevier Ltd. All rights reserved.