Unraveling the reaction mechanisms of gasoline soot combustion over Ru/CeO2 catalysts: Mind the heterogeneity of Ru-based species

Ru/CeO 2 recipes have gained increasing attention as cost-effective catalysts for soot combustion under the NO x -free and oxygen-lean conditions characteristic of gasoline particulate filters (GPFs). Nevertheless, the intrinsic heterogeneity of Ru-based species in these catalytic systems has not been adequately addressed, resulting in ambiguous structure-activity correlations and an incomplete mechanistic picture. In this study, we aim to bridge this gap by systematically investigating a model Ru/CeO 2 catalyst (∼1 wt% Ru) supported on nanocube-shaped CeO 2 . Combining kinetic analysis, transient oxygen cutoff experiments, and spectroscopic characterization, we identified two distinct types of Ru-based active entities: sub-nanometer RuO x clusters strongly interacting with the support and larger RuO 2 nanoparticles. Although both species contributed to soot combustion, the nanoparticles underwent irreversible reduction under oxygen-lean atmospheres, whereas the RuO x clusters maintained redox stability via dynamic oxygen exchange with the CeO 2 support. These findings underscore the essential role of recognizing and regulating metal species heterogeneity in catalyst design, laying a foundation for the development of more efficient and durable Ru/CeO 2 catalysts for automotive emission control.