Vacancy-Engineered Perovskite Ferrites Stabilize Atomic Ru Sites and Activate Lattice Oxygen for Photothermal Methane Dry Reforming.

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.