Catalytic NO Reduction by NO Pre-Adsorbed RhCeO2NO- 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 RhCeO2- can create a Ce3+ ion in product RhCeO2NO- 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 N2O takes place exclusively on the Ce3+ ion while Rh behaves like a promoter to buffer electrons and cooperates with Ce3+ 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/CeO2, one of the most efficient components in three-way catalysts for NOx removal.