Surface-engineered perovskite oxides enabling dual activation of lattice and adsorbed oxygen for CO oxidation

Catalytic oxidation using perovskite oxides is a promising technology for mitigating environmental and health risks associated with CO emissions. A fundamental constraint for perovskite oxides, however, lies in the limited low-temperature reactivity of oxygen species. While the dual activation of lattice oxygen (O_latt) and adsorbed oxygen (O_ads) is recognized as an effective strategy, achieving it in perovskite oxides remains a significant and underexplored challenge. This study addresses this challenge through a novel surface engineering strategy employing dilute TiCl₄ solution treatment. The treatment process on La_0.6Sr_0.4CoO₃ (LSCO) simultaneously achieves two distinct functions: (i) the removal of surface A-site segregation to expose Co-site termination, thereby facilitating O_ads activation; (ii) the incorporation of Ti dopant, which enhances the CoO covalency to boost O_latt reactivity. This concerted dual activation mechanism enables the LSCO-Ti catalyst to operate via both Mars–van Krevelen (O_latt-mediated) and Langmuir–Hinshelwood (O_ads-mediated) pathways, leading to its exceptional activity of 90% CO conversion at a remarkably low temperature of 92°C. Furthermore, the Ti dopant also optimizes O₂ adsorption and suppresses carbonate accumulation, ensuring stable performance for over 50 h at 150°C. Our work provides a novel mechanistic framework for designing high-performance perovskite catalysts via synergistic surface modification.