Selective Reduction of NO into N 2 Catalyzed by Rh 1 -Doped Cluster Anions RhCe 2 O 3-5 .

Catalytic conversion of toxic nitrogen oxide (NO) and carbon monoxide (CO) into nitrogen (N 2 ) and carbon dioxide (CO 2 ) is imperative under the weight of the increasingly stringent emission regulations, while a fundamental understanding of the nature of the active site to selectively drive N 2 generation is elusive. Herein, in combination with state-of-the-art mass-spectrometric experiments and quantum-chemical calculations, we demonstrated that the rhodium-cerium oxide clusters RhCe 2 O 3-5 - can catalytically drive NO reduction by CO and give rise to N 2 and CO 2 . This finding represents a sharp improvement in cluster science where N 2 O is commonly produced in the rarely established examples of catalytic NO reduction mediated with gas-phase clusters. We demonstrated the importance of the unique chemical environment in the RhCe 2 O 3 - cluster to guide the substantially improved N 2 selectivity: a triatomic Lewis "acid-base-acid" Ce δ+ -Rh δ- -Ce δ+ site is proposed to strongly adsorb two NO molecules as well as the N 2 O intermediate that is attached on the Rh atom and can facilely dissociate to form N 2 assisted by both Ce atoms.