Defect-Engineered LaFeO Stabilizing Oxidized Pt Single-Atom Sites for Low-Temperature CO Oxidation.

The inherent trade-off between activity and stability in platinum single-atom catalysts (SACs) poses a significant challenge for catalytic oxidation reactions. High-coordination Pt sites have good stability, but their overoxidation often passivates activity. In contrast, metastable low-coordination Pt structures typically display high activity but are prone to oxidation and aggregation under harsh conditions. Herein, we propose a defect-engineering strategy to address this dilemma by anchoring oxidized Pt single atoms onto vacancy LaFeO (v-LaFeO) perovskite. The introduced La-vacancy substantially reduces the oxygen vacancy formation energy of LaFeO, enhancing lattice oxygen mobility while preserving structural integrity. Pt single-atom sites with a high oxidation state (Pt) are anchored on the support, and their coordination environments are optimized. The catalyst exhibits high and stable activity for CO oxidation without reduction pretreatment. The structural characterization and in situ experiments indicate that vacancies in LaFeO positively regulate the electronic structure between the Pt and v-LaFeO interface. The longer Pt-O bonds activate interface oxygen species, accelerate O activation, and promote the cycling of CO oxidation. The oxidized Pt atoms and high coordination number enable its stability in long-term and high-temperature oxidation reactions. DFT calculations further verify the structure and reaction mechanism. This work demonstrates that precise control of support defects can concurrently optimize the electronic states and stability of SACs, offering a generalized paradigm for designing robust oxidation catalysts.