Selective Reduction of NO into N Catalyzed by Rh-Doped Cluster Anions RhCeO.

Catalytic conversion of toxic nitrogen oxide (NO) and carbon monoxide (CO) into nitrogen (N) and carbon dioxide (CO) 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 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 RhCeO can catalytically drive NO reduction by CO and give rise to N and CO. This finding represents a sharp improvement in cluster science where NO 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 RhCeO cluster to guide the substantially improved N selectivity: a triatomic Lewis "acid-base-acid" Ce-Rh-Ce site is proposed to strongly adsorb two NO molecules as well as the NO intermediate that is attached on the Rh atom and can facilely dissociate to form N assisted by both Ce atoms.