First Principles' Calculations of CO Adsorption on Bimetallic Nickel-Iron Clusters

Abstract

Density functional theory (DFT) calculations using the Generalized Gradient Approximation (GGA) functional are performed to investigate the structural, energetic and magnetic properties of bimetallic alloyed  isomers (N = 2-6 and N = 43, n = 0 to N). The negative mixing energies indicate the stability of these clusters as compared to Ni and Fe bare clusters. All clusters exhibit high spin ground states, with a significant decrease in the magnetization per atom for Fe₁₉Ni₂₄ cluster with the iron core. The adsorption energies of CO on the most stable isomers of alloyed clusters are lower than those on Fe clusters with the same structure. This behavior indicates a decrease of CO poisoning and an increase of methanol oxidation reaction (MOR) activity upon alloying.