Conversion of multilayer graphene into ultrathin diamond-like material

Abstract

We studied how multilayer graphene can undergo transformation into sp3 structure by using density functional theory (DFT) method and predicted diamond-like properties in multilayered sp3 structures at varying thickness. Herein, hydrogenation of multilayer graphene at the both sides of surface induce a sp2 to sp3 transition and as a result, a diamond-like structure can be obtained. Surface hydrogenation reduces the transition barrier due to the low stability of hydrogen passivated graphene layer caused by unpaired electrons. Electronical and mechanical properties of sp3 multilayer graphene were calculated by varying the number of carbon layers and the stacking orientation of the sp3 structure. The sp3 structure exhibited various electronical and mechanical properties indicative of a diamond material, except that the electrons of conduction band were mainly distributed at the hydrogenated surface. This is due to the top and bottom surface stabilization through termination with hydrogen. By extrapolating the band gap and Young’s modulus of our structures under consideration, we successfully identified the thinnest possible sp3 structures that exhibit diamond-like properties.