Geometrical features, electronic properties and chemical adsorptions of Co-doped Cu clusters

The growth patterns, electronic structures and chemical adsorptions of CoCun (n = 1–9) clusters are first analysed in detail. The structural transitions of them are found to occur at the CoCu5, where the Co atoms tend to stabilise at the vertex sites with high-coordination numbers, and the delocalised characteristic of frontier orbits is key for influencing geometric stability. Spin multiplicities that are modulated by the presence of the Co atom vary irregularly. The density of states (DOS) of larger sized CoCun can be regarded as the superposition of small clusters, and distributions of the DOS curves are in good agreement on the whole. The charge analyses show that the direction of charge flows is from the Cun frameworks→Co. The electrostatic potential surfaces confirmed that the CoCun have significant σ-hole regions that can make C – O stretching frequencies and bond lengths have red-shifts. The adsorption energies between CoCun and CO range from 1.12 eV to 1.64 eV, involving the 5σ orbital from CO to the Cu and π*-back-donation from the Cu to CO.