Engineering of Ti_N (N = 1 – 15) nanoclusters by doping osmium impurity

Materials Modelling Centre, University of Limpopo, Private bag X1106, Sovenga, 0727, South Africa

Abstract

Bimetallic transition metal nanoclusters have attracted significant attention in recent years due to their wide range of applications such as heterogeneous catalysts, electrochemistry and alloy design. However many studies were reported on pure transition metal nanoclusters and bimetallic of late transition metal nanoclusters. In this study the density functional theory (DFT) with PBEsol exchange correlation functional was employed to investigate the structural and electronic properties of Ti_N-1Os (N = 2-16) nanoclusters. The calculations showed that osmium impurity mostly prefers to be encapsulated by titanium nanoclusters. The binding energies gradually decrease with the cluster size N. The Os dopant was found to enhance the binding energy of titanium nanoclusters. The relative stability or second order energies showed that Ti₆Os and Ti₁₂Os clusters are the most stable. Interestingly, osmium dopant converted the nanocluster with 13 atoms to be the most stable. Furthermore, the dissociation energy or first order energies showed an excellent correlation with the relative stability trend. The HOMO-LUMO revealed the lowest energy gap at Ti₁₂Os (N = 13) which correlates well with the predicted binding energy, relative stability and dissociation energy.