Semiconducting nature of the oxygen-adsorbed graphene sheet

Structural and electronic properties for oxygen-adsorbed graphene sheets have been explored using first-principles total-energy calculations within the local density functional theory. A finite energy gap emerges for the oxygen-adsorbed graphene and its value increases with the ratio of O/C, as manifested by experiments. Further, adsorption energy and migration barrier for oxygen atoms on the graphene sheet have been investigated. The results show that isolated oxygen atoms are highly mobile and incline to condense on the graphene sheet. (C) 2008 American Institute of Physics.