Electronic and magnetic properties of hydrogenated graphene nanoflakes

We investigated the energetic stability, electronic, and magnetic properties of hydrogenated graphene nanoflakes (GNFs) by using density-functional theory (DFT). Hydrogenated GNFs were found to be the stable heterojunction structures. As the increase of H coverage, a transition of a small-gap semiconductor to wide-gap semiconductor occurs, accompanied with a nonmagnetic (with the coverage χ=0χ=0) → magnetic (with the coverage 0<χ<10<χ<1) → nonmagnetic (with the coverage χ=1χ=1) transfer for hexagonal nanoflakes and magnetic (with the coverage 0⩽χ<10⩽χ<1) → nonmagnetic (with the coverage χ=1χ=1) transfer for triangular nanoflakes. The efficacious tune of band gaps and the magnetic moments on these nanoflakes by hydrogenation offers an effectual avenue for the applications of C-based nanomagnets.

► Hydrogenated GNFs were found to be the stable heterojunction structures.
► A transition of a small-gap semiconductor to wide-gap semiconductor occurs with the increase of H coverage.
► For hexagonal nanoflakes, a nonmagnetic → magnetic → nonmagnetic transition occurs with the increase of H coverage.
► For triangular nanoflakes, a magnetic → nonmagnetic transition occurs with the increase of H coverage.