Ab Initio Study of the Adsorption of Small Molecules on Stanene

Recent reports focus on the experimental preparation of metal monolayer-stanene which is a zero-gap semiconductor with buckled honeycomb structure. Owing to the outstanding properties of stanene, its promising applications in nanoelectronics are widely concerned and studied. Using the first-principles calculations, we investigate the adsorption behavior of CO, NH3, H2O, H2S, O-2, NO, and NO2 molecules on a stanene sheet based on the energetics, charge transfer, and work function. We determine the optimal adsorption sites of small molecule on the stanene sheet and the styles of molecule doping, and discuss the interaction mechanism between the molecule and stanene. The results indicate that the sensing performance of stanene is superior to other 2D materials such as silicene and germanene. It is found that CO, O-2, NO, and NO2 molecules act as charge acceptors, whereas NH3, H2O, and H2S molecules serve as charge donors. For nonpolarized molecules, the molecule-stanene interaction is mainly ascribed to the electrostatic attractions effect. In contrast, for polarized molecules, the covalent interaction plays a critical role in the process of adsorption. We further investigate the variation of the work function for small molecules' adsorption on stanene. The work function calculations exhibit various responses to the different molecules, which indicate that the Schottky barrier height can be effectively tuned by the selective adsorption of these small molecules. The nontrivial sensitivity and selectivity of stanene show that it has a potential application in the field of gas sensors and high performance catalysts.