Prediction of sp3-tized diamond like structure induced by surface hydrogenation of multilayer graphene

Abstract

We investigated multilayer graphene transformation into sp3 structure using density functional theory (DFT) calculation and predicted diamond-like properties in multilayered sp3 structures at various thickness. The hydrogen atom adsorptions onto both surface sides of the multilayer graphene induced the transformation of the multilayer graphene into the sp3-hybridized structure with small energy barrier and large heat of reaction. As the number of sp2 layer decreased and hydrogen adsorption became relatively large, the transformation of the sp2 structure into sp3 configured structure became energetically favorable. Further, electronic and mechanical properties of sp3 multilayer graphene were calculated by varying the number of layers and the stacking order of the sp3 structure. The sp3 structure exhibited various band gap (2.2~3.5 eV) and Young’s modulus (700 ~ 1050 GPa) indicative of a diamond material, except that the electrons of conduction band were mainly located at the hydrogenated surface. By extrapolating the band gap, Young’s modulus and structure properties, we theoretically predicted that the thinnest possible sp3 structure, that could contain diamond-like properties.