Adsorption of gas molecules on graphene, silicene, and germanene: A comparative first-principles study

Abstract

Silicene and germanene, the Si and Ge analogs of graphene, have recently extended the list of existing twodimensional atomic crystals. They have attracted great interest in various fields, ranging from electronics to energy, owing to their unique properties. In this work, we employed density functional theory to examine the dissociative adsorption of NH3, PH3, H2O, and H2S on graphene, silicene, and germanene two-dimensional materials. We found that the molecular adsorption energy is similar for all the molecules. However, the dissociative adsorption energy on silicene was significantly lower than that of germanene and graphene. Almost all the dissociative adsorptions on the silicene surface were exothermic, whereas those on the graphene and germanene surfaces were endothermic. The most stable dissociative adsorption was found at the para position. Overall, this study reveals that dissociative adsorption is more feasible on germanene and silicene compared to that on graphene.