Surface reconstruction-induced heterostructures in La_0.5Sr_0.5MnO₃ for stable oxygen vacancies and enhanced hydrolysis-assisted oxidation of chlorobenzene

Efficient catalytic oxidation of chlorinated volatile organic compounds (CVOCs) requires stable and sustained utilization of the oxidization reactants and effective chlorine desorption, which can be promoted by surface lattice oxygen. Given this, a surface-engineered La_0.5Sr_0.5MnO₃ catalyst (LSMO-E) was developed via urea pyrolysis and buffer etching that introduces oxygen vacancies (OVs) to maximize gaseous oxidants utilization even under humid conditions. We found that the OVs generated through Sr segregation can be stabilized by C₃N₄ heterojunction formed after urea pyrolysis. Moreover, the facile exposure on Mn-terminal introduced minimal perturbation to the surface Mn states. As a result of 74 °C lower than that of pristine perovskite, LSMO-E exhibited superior activity of achieving 90% chlorobenzene (CB) conversion at 298 °C. Distinguished from conventional reduction strategy, it was confirmed that OVs formation weakens Mn–O bonding strength without compromising the Mn^{4 +} /Mn³⁺ redox cycle. The presence of C₃N₄ heterojunctions enhanced catalyst surface hydrophilicity, generating a proton-rich environment that promoted hydrolysis-assisted oxidation and mitigated the inhibitory effects of H₂O at elevated temperatures. Notably, the hydrolysis route triggered by H₂O-dissociated hydroxyl radicals (∙OH) and ∙H accelerated the desorption of surface-bound ∙Cl, skipped the step of (chloro-)quinoline intermediate during CB decomposition, remarkably suppressing the generation of chlorinated byproducts. This work shows the efficient strategies to create stable OVs and MnO₂ terminals on the perovskite surface with robust tolerance to Cl poisoning, provides new insights into design of multifunctional catalysts for efficient CVOC abatement under simulated conditions.