Blocking the <i>Operando</i> Formation of Single‐Atom Spectators by Interfacial Engineering

Abstract Aside from activity and selectivity, catalyst stability is a key focus in heterogeneous catalysis research. Although sintering of metal species has been considered the primary cause for deactivation of metal catalysts, our study reveals that the loss of activity at low reaction temperatures in the CeO 2 ‐supported Pt (Pt/CeO 2 ) catalyst in complete propane oxidation is due to the dispersion of Pt ensemble sites (nanoclusters) and their subsequent operando conversion into Pt single atoms under reaction conditions. These Pt single‐atom species exhibit low reactivity and act as spectators in the low‐temperature reaction region. To address this issue, we engineered the surface of CeO 2 by introducing NbO x , which does not directly interact with Pt. Instead, NbO x blocks the strong binding sites for Pt on CeO 2 , thereby preventing Pt redispersion/fragmentation and preserving reactive Pt ensembles. This strategy led to a remarkable 37‐fold increase in the reaction rate compared to the Pt/CeO 2 catalyst. Our findings emphasize the importance of suppressing the formation of noble metal single‐atom spectators through innovative surface engineering strategy. These mechanistic insights not only advance the understanding of the materials science of Pt/CeO 2 but also extend to critical technological fields such as energy conversion systems and environmental remediation technologies.