DFT study of Pt7-x Rux (x = 0, 1, 2, 3) clusters and their interactions with CO

Abstract

Density functional theory based calculations are performed to study structures and properties of coupled tetragonal pyramid (CTP) Pt7 based Pt7−x Ru x (x = 1, 2, 3) clusters as well as their interactions with a CO molecule. Among the PtRu isomers studied, the clusters with the Ru atoms occupy the bottom sites of CTP Pt7 are more stable than other homotops. Furthermore, the bimetallic clusters are more stable than Pt7 and the most stable one is aPt5Ru2. The natural orbital analysis shows that the charge transfer from Ru to Pt atoms enhancing the stability of PtRu clusters. Frontier molecular orbital theory is used to predict the selectivity of CO adsorption on these metal clusters. The adsorption energy, CO bond stretching frequency, geometries of the PtRu-CO system and electronic-structure details have been investigated about the interaction between CO and metal clusters. The CO prefers to adsorb on Pt than on Ru and the adsorption energy on Pt will decrease with increasing of Ru content. Electronic-structure details are discussed to explain the observed results and analyze the interaction between CO and metal clusters.