Steam‐Activated Lattice Oxygen Enhances Interfacial Redox Stability for Low‐Temperature N ₂ O Decomposition over Rh/CeO ₂

Activation of surface lattice oxygen is crucial for enabling low-temperature catalytic oxidation reactions. While earlier studies have hinted that steam treatment could enhance the activity of lattice oxygen in CeO₂ supported catalysts, the mechanistic understanding remains superficial. Here, we unravel the origin and role of steam-activated lattice oxygen in promoting low-temperature N₂O decomposition. Using a combination of isotope-labeled steam (H₂ ¹⁸O), in situ ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), and in situ X-ray absorption spectroscopy (XAS), we provide direct evidence that high-temperature steam induces lattice oxygen activation at the Rh-CeO₂ interface. These activated oxygen species facilitate oxygen desorption and enhance the redox cycling stability of Rh and Ce species, dramatically improving catalytic activity at low temperatures. Our findings reveal a previously overlooked pathway for surface lattice oxygen activation and offer mechanistic insights to guide the rational design of efficient low-temperature redox catalysts.