Methane Activation at the Pd/CeO₂ Interface

We combine density functional theory (DFT) and reactive force-field (ReaxFF) simulations to assess the stability and activity of unique catalytic sites at the interface between Pd clusters and a CeO₂ support. ReaxFF-based Grand Canonical Monte Carlo (GC-MC) simulations provide insight into the oxide structure at the Pd/CeO₂ interface. Surface models derived with GC-MC are employed in reactive molecular dynamics (RMD) simulations, which demonstrate that methane lightoff rapidly occurs when there is Pd mixing in the CeO₂ lattice. DFT investigations, utilizing models inspired by GC-MC/RMD, demonstrate that Pd⁴⁺ states are stabilized in PdO_x clusters partially embedded in the CeO₂ lattice, and that such sites yield low methane activation barriers. The integrated DFT/ReaxFF methodology employed here demonstrates a combined quantum/classical workflow that can be extended to examine emergent behavior in other oxide-supported metal catalysts. (Chemical Equation Presented).