Metallic-semiconducting phase transition of the edge-oxygenated armchair graphene nanoribbons

►The edge-oxygenated AGNRs exhibit complex metallic energy band. ►Metallic-semiconducting phase transition can be realized by applying electric fields for edge-oxygenated AGNRs. ►Band gap modulation can be realized by different transverse homogeneous electric fields. ►Critical electric field for achieving semiconducting phase decreases as the width of edge-oxygenated AGNRs decreases. ►Range of electric field for semiconducting phase maintained increases as the width of edge-oxygenated AGNRs decreases.