Density functional study of NOx binding on small AunCum (n + m ≤ 5) clusters

Density functional theory calculations were performed to investigate the structural and energetic properties of NO, NO2 and NO3 binding on small bimetallic AunCum clusters (n + m ≤ 5). The adsorbates prefer binding to Cu atoms when both Au and Cu co-exist in the cluster. In general NO is located at top site via the N atom while NO2 and NO3 are located at bridge site via the O atoms. The binding energies and the electron transfer from metal clusters to the adsorbates follow the same order NO3 > NO2 > NO. Besides, the dope of Cu atoms in Aun clusters can greatly increase the binding energy with respect to pure Aun. The N–O vibrational properties of the complex clusters were also discussed and analyzed.