First-Principles Study Of Adsorption Properties On Doped Aluminium Oxygen Clusters

Clusters, as a new object, have been attracted many scientists'attention because of their novel and unique properties. It is useful for us to understand the substances from microcosmic to macroscopic.Al cluster absorb atom or molecule, with could bring about the variety of structures and electronic properties. Studies on them help to understand electronic properties of clusters and discover cluster that are chemically stable. Moreover, the rule of clusters adsorption will help us to better understand the adsorption properties of the surface.The adsorption properties of oxygen on doped Al12 clusters with C, Si and P+ atoms are investigated using density functional theory. The adsorption energy of three different sites of O (on-top, bridge and hollow form), HOMO-LUMO gap and charge transform are studied, respectively. Results show that O atom occupy the hollow site on the X@Al12 surfaces are energetically more preferable. Similar behavior of oxygen on C@Al12, Si@Al12 and P+@Al12 are found. Remarkably difference of adsorption properties is found between X@Al12 (X=C, Si, P+) and Al13-. O prefers to occupy the bridge site on Al13-. Different adsorption behavior of X@Al12(X=C, Si, P+) and Al13- stem from their different electronic structure. It implies that the properties of clusters can be alternated by doping with other atoms.The interaction of O2 with the doped icosahedral X@Al12 (X=Al-, P+, C, Si) clusters with 40 valence electrons were investigated using density functional theory methods. A different behavior exhibited between Al13- and X@Al12 (X=P+, C, Si) when they interact with O2. The dissociation of O2 on Al13- is strongly dependent on spin state of oxygen molecule. But X@Al12 (X=P+, C and Si) is not the case. The transform of spin moment from O2 to Al13- is much faster. Small molecularly binding energy and relatively high energy barrier show that these clusters are all reluctant reacts with the ground state O2.These results demonstrated that the properties of X@Al12 clusters can be tuned by changing the central impurity atoms inside the superatom clusters, and it supported the concept of superatom that can be used to design new nanoscale catalysts with desirable properties.