Reaction intermediates of CO oxidation on gas phase Pd4 clusters: a density functional study.

Density functional theory (DFT) studies have revealed the energetically favorable reaction paths for oxidation of CO on Pd(4) cluster. Adsorption of various species such as O(2), 2O, O, CO, CO(2), and coadsorbate combinations, including O(2)+CO, 2O+CO, O+CO, and O+CO(2) on neutral, cationic, and anionic Pd(4) clusters were investigated. The results indicate that Pd(4)(+) and Pd(4) are more effective for catalyzing CO in comparison with Pd(4)(-). It is further observed that dissociated oxygen is a superior oxidant for CO oxidation on Pd(4)(q) (q = 0, 1, -1) than molecular and atomic oxygen.