Vacancy-EngineeredPerovskite Ferrites Stabilize AtomicRu Sites and Activate Lattice Oxygen for Photothermal Methane DryReforming

Abstract Photothermal dry reforming of methane (DRM) mediated by lattice oxygen (OL) via a Mars–van Krevelen pathway is a promising route for converting greenhouse gases into syngas. However, this strategy is limited by the instability of single-atom cocatalysts under reaction conditions and the sluggish migration of OL in conventional oxide supports. Here, we report a vacancy-engineered perovskite ferrite (LaFe1–xO3) that simultaneously stabilizes atomic cocatalysts and accelerates OL dynamics for efficient photothermal DRM. Introducing Fe defects generates robust anchoring sites for atomic Ru cocatalysts (Ru1) while weakening the La–O–Fe framework to promote OL mobility. The optimized Ru1/LaFe1–xO3 catalyst enables light-driven DRM without external heating, achieving high syngas production (H2: 53.6 and CO: 66.1 mol gRu–1 h–1), a methane turnover frequency of 1.3 s–1, and stable operation over 180 h. Mechanistic studies reveal that vacancy-induced electron localization facilitates OL migration, while photoinduced metal-to-metal charge transfer enriches Fe sites with electrons and activates surface OL with holes. This cooperative process selectively oxidizes CH3* to CH3O*, suppressing deep dehydrogenation and coke formation. These findings propose defect engineering as a general strategy to couple atomic cocatalyst stabilization with OL activation for solar-driven catalytic transformations.