The Study Of Graphene And Molybdenum Sulfide,Based On The First Principles Calculation And Experimental Synthesis

Recently, the research on two-dimensional materials, such as graphene and molybdenum sulfide (MoS2) attracts many attentions, due to the outstanding physical and chemical properties. The hybrid structures, fabricated by the graphene and MoS2, show the unique photoelectronic performance which is worth to be studied. Thus, in this thesis, we focus on the graphene/MoS2heterostructures by using both the first principles calculations and experimental synthesis which include the study of the morphology and instinct properties of heterostructures.In the part of theoretical calculations, we first argue the stacking arrangement of graphene/MoS2structures because the stacking orders can have the influence on the properties of hybrid structures. Here, we propose a "least squares" classification method for analyzing configuration types of graphene/molybdenum disulfide heterobilayers (G/MoS2HBLs). Owing to the lattice mismatch, no traditional AA and AB stacking exist but AA-and AB-stacking-like configurations have been found. Paradoxically, AB-stacking-like configuration, generally as the most stable stacking sequence, doesn’t correspond to the relaxed structure. We interpret this paradox in terms of graphene corrugation.Furthermore, the binding energy, electronic structure and optical absorption of G/MoS2HBLs are investigated via first principles calculations. A detailed analysis of the electronic structure indicates that bandgaps of all configurations types (types of G/MoS2HBLs) are opened and tunable under the different interlayer distance. Finally, through the analysis of imaginary part of the dielectric function, we found G/MoS2HBLs, compared with monolayer MoS2, display an enhanced light response, a promising feature for photocatalytic applications.In the part of experimental synthesis, our works are based on the liquid exfoliation strategy. Under the influence of solvent and ultrasound, the monolayer graphene is successfully exfoliated. Besides, by mixing the composition of powders, the hybrid structures of graphene/MoS2exist in the solution. That means liquid exfoliation has the potential application in the synthesis of heterostructures of two-dimensional materials.