Density functional theory study of BiRun (n=3-20) clusters: Structural, electronic and adsorptive properties for hazardous gases

The geometric structures and electronic properties as well as adsorption of some harmful gas molecules for BiRun (n = 3-20) clusters are investigated using the generalized gradient approximation of density functional theory (DFT/GGA). The clusters largely show low symmetries (e.g., C-s) and generally exhibit the polyhedral structures with Bi atom at the vertices, while BiRu6, BiRu11, BiRu12 and BiRu17 clusters have the highest C-5V symmetry and stability. Interestingly, the structure of BiRun (n = 3-20) clusters shows growth property, i.e., construction of BiRun (n = 3-20) by addition one Ru atom to BiRun_ 1, and Ru-n and Ru-n_ 1 clusters also have similar geometrical structures. BiRu5 and BiRu12 are found to exhibit relatively higher thermodynamic stability from the second -order energy difference. BiRu12 and BiRu6 can display the highest chemical stability and activity in view of the largest and smallest energy gap E-g, respectively. Vertical ionization potential (VIP) and vertical electron affinity (VEA) show the decreasing and increasing trends with n, respectively. As for the adsorption properties of these clusters for harmful gas molecules, excellent and good adsorption performances are found for CO and NH3 molecules adsorbed on BiRu14 and BiRu20, whereas NO and H2S molecules exhibit poor adsorption properties on these clusters. The study of this work would be helpful to construct and characterize the electronic properties of BiRun (n = 3-20) clusters and to explore their potential adsorption performances and the prospect to act as efficient sensors for the harmful gases.