Stabilization of monovalent and mixed valent cations in snnom clusters and predictive applications – First Principles Calculations
In this work, the stoichiometric dependent structural stability and electronic properties of tin oxide nanoclusters (SnnOm, n = 1 - 6; m = 1 - 2n) is explored by employing first principles density functional calculations. The results show that stable SnnOn (m = n) clusters found to have large binding energy, in given n series, due to having high structural symmetry, large energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO gap), and univalent charge distributions among Sn and oxygen atoms. On the other hand, stable SnnO2n clusters have possessed with mixed charge states of Sn2+ and Sn4+ ions. The presence of both Sn2+ and Sn4+ ions in these clusters originates weakly adsorbed O2 molecule on these clusters, which is quite consistent with earlier experimental work. Interestingly, the structure of some of large sized stable clusters is observed to be resemblance with fused form of two stable isomers. By calculating chemical hardness of SnnOm clusters, we also show that SnnOn clusters are chemically inert and they can be used for optoelectronic devices owing to presence of lone pair Sn2+ ions. Whereas, in SnnOm clusters (m > n), both Sn2+ and Sn4+ ions are presented, thus, they can be used for catalytic or sensing applications.
Faculty of Science, University of Uyo