Single-Atom Ru on CeO₂ Nanorods for Efficient N₂O Decomposition: Mechanistic Insights and Multipollutant Control

Nitrous oxide (N₂O) has gained increasing attention as a potent greenhouse gas, and its catalytic decomposition offers a promising mitigation strategy. In this study, single-atom Ru embedded in a rod-shaped CeO₂ catalyst was synthesized via a H₂O₂ chemical etching strategy. The single-atom Ru catalyst demonstrated an exceptional N₂O decomposition performance with only 0.48 wt % Ru loading, exhibiting a 34-fold increase in the turnover frequency compared to Ru nanoparticle catalysts. Under simulated exhaust conditions (NO, CO, and N₂O), Ru₁/CeO₂ enabled complete conversion of all three pollutants at 280 °C. Mechanistic studies revealed that N₂O decomposition over Ru₁/CeO₂ and Ru_n/CeO₂ followed the Mars-van Krevelen (MvK) and Langmuir-Hinshelwood (L-H) mechanisms, respectively. The exceptional N₂O decomposition activity of the single-atom catalyst stems from enhanced O₂ desorption through the recombination of oxygen atoms that dissociate from N₂O with adjacent lattice oxygen. Notably, Ru₁/CeO₂ exhibits remarkable O₂ tolerance due to the selective adsorption: N₂O binds to single Ru atoms, whereas O₂ occupies oxygen vacancies. In contrast, the high energy barrier associated with O₂ combination and desorption in Ru_n/CeO₂ hindered N₂O decomposition, and the competitive adsorption of O₂ on its surface led to poor O₂ resistance. This study demonstrates Ru₁/CeO₂ as an efficient catalyst for abating N₂O and multipollutant removal.