Influence of crystal facets of SrTiO3 nanosheet supports on Pd catalysts for automotive exhaust purification

This study examines how the exposed crystal facets of SrTiO₃ (STO) nanosheets affect the catalytic behavior of supported Pd nanoparticles for automotive exhaust purification. The Pd/STO(111)-facet nanosheet shows lower light-off temperatures for CO–C₃H₆ oxidation and NO reduction than the Pd/STO(100)-facet nanosheet, even though its surface area is much smaller. Structural analyses reveal that the STO(111) facet creates a much stronger metal–support interaction (MSI), stabilizing highly dispersed Pd nanoparticles (≈4.6 nm) and maintaining both PdO and Pd⁰ during the reaction. This strong MSI suppresses sintering and supports dual oxidation states, leading to superior catalytic performance. In contrast, the weaker MSI on the STO(100) facet allows Pd to grow into large particles (≈60.2 nm) with limited redox flexibility and fewer active sites, resulting in poorer activity. These results demonstrate that the facet-dependent MSI is the key to controlling Pd dispersion and oxidation-state dynamics, highlighting crystal facet engineering as an effective strategy for designing high-performance oxide-supported catalysts.