Big Bandgap in Highly Reduced Graphene Oxides

Abstract

It is generally believed that the\nbandgap of the graphene oxide\nis proportional to the concentration of the oxygen atoms and a highly\nreduced graphene oxide (rGO) without vacancy defects should be gapless.\nWe show here from first principles calculations that the bandgap can\nbe effectively opened even in low oxidation level with the absorption\nof oxygen atoms either symmetrically or asymmetrically. The properly\narranged absorption can induce a bandgap up to 1.19 eV for a C/O ratio\nof 16/1 in a symmetric system and a bandgap up to 1.58 eV for a C/O\nratio of 32/3 in an asymmetric system, at generalized gradient approximation\n(GGA) level. The hybridization between the in-plane p_<i>xy</i> orbitals of oxygen atoms and the out-of-plane p_<i>z</i> frontier orbital of graphene is responsible\nfor the opening of the bandgap. This finding sheds new light on the\nbandgap engineering of graphene.