Catalytic NO Reduction by NO Pre-Adsorbed RhCeO 2 NO - Clusters.

A fundamental understanding on the dynamically structural evolution of catalysts induced by reactant gases under working conditions is challenging but pivotal in catalyst design. Herein, in combination with state-of-the-art mass spectrometry for cluster reactions, cryogenic photoelectron imaging spectroscopy, and quantum-chemical calculations, we identified that NO adsorption on rhodium-cerium bimetallic oxide cluster RhCeO 2 - can create a Ce 3+ ion in product RhCeO 2 NO - that serves as the starting point to trigger the catalysis of NO reduction by CO. Theoretical calculations substantiated that the reduction of another two NO molecules into N 2 O takes place exclusively on the Ce 3+ ion while Rh behaves like a promoter to buffer electrons and cooperates with Ce 3+ to drive NO reduction. Our finding demonstrates the importance of NO in regulating the catalytic behavior of Rh under reaction conditions and provides much-needed insights into the essence of NO reduction over Rh/CeO 2 , one of the most efficient components in three-way catalysts for NO x removal.