Quantum computational study of small bismuth–cobalt nanoalloy clusters

Structural evolution, electronic, magnetic and optical properties of small bimetallic BinCom (n + m ≤ 5) hybrid nanoclusters are investigated by using density functional theory involving generalized gradient approximation. All the possible two and three-dimensional structures have been considered for optimization to obtain a stable ground state isomer and different thermodynamical parameters binding energy (BE), energy gap between the highest occupied and lowest unoccupied molecular orbitals (HOMOLUMO), magnetic moments of the energetically stable clusters in each size have been calculated. We found a general trend that average binding energy of bimetallic BiCo nanoalloy increases with Co and Bi doping. Planar structures of pure Bi and Co clusters changed in 3D with the addition of doped atom. Bi3Co, Bi4Co, BiCo2, BiCo3, and BiCo5 nanoalloy clusters are found as most stable species since they have higher energy gap and binding energy than the others. The interatomic charge transfer also plays a role in enhancing the magnetic moment and optical gap that can be tuned within the full range of visible light by changing the number of Co and Bi atoms. This gives possibility of using these clusters for photo-catalytic water splitting and spintronic applications.