Decomposition of AunO- clusters into gold oxide and metallic components: Unraveling the impact of single-atom oxygen on the reactivity modulation.

Gold clusters serve as ideal models for probing chemical bonding theories and their reactions with O2 provide valuable insights into the O2 activation mechanisms on gold-based catalysts. While extensive research has been conducted on pristine gold clusters, investigations into the reactivity of nonmetal-doped gold clusters remain limited. Here, we explore the reactions of AunO- (n = 5-20) with O2 using cluster reaction experiments and density functional theory calculations, and our findings reveal that many AunO- exhibits a structure-activity relationship different from those of pure gold clusters and small gold oxide clusters. In these AunO-, the oxygen atom bonds with two or three adjacent gold atoms, creating a metal oxide unit, while the remaining gold atoms constitute a metallic component. The reactivity of these AunO- is predominantly dictated by its metallic part, which is affected by the ease of electron transfer to O2. The decomposition of these AunO- into oxide and metallic components aligns with the strategy of partitioning ligand-protected noble metal clusters into a covalent outer shell and a metallic core and also enriches the emerging framework of the superatomic molecule concept in cluster science. Moreover, these insights offer valuable clues for understanding the behavior of gold clusters supported on oxide surfaces.